-
حرية الوصول المقاله
1 - A study of the corrosion of stainless steel 304L coated with a 190 nm-thick manganese layer and annealed with nitrogen flux in a 0.4-mole solution of H2SO4 at different temperatures
Farzaneh Modiri Hadi SavaloniAbstractA method for enhancing the resistance against corrosion of stainless steel 304L coated with 190 nm-thick manganese film and annealed with nitrogen flux at constant temperature (723 K) is reported. The variable quantity in this work is the temperature of the corr أکثرAbstractA method for enhancing the resistance against corrosion of stainless steel 304L coated with 190 nm-thick manganese film and annealed with nitrogen flux at constant temperature (723 K) is reported. The variable quantity in this work is the temperature of the corroding solution (293 K and 333 K). X-ray diffraction analysis was employed to investigate the crystallographical changes of the annealed samples; atomic force microscope and scanning electron microscope were used for the morphology and studying the roughness of their surfaces; polarization analysis, electrochemical impedance spectroscopy, and phase and Bode diagrams, as well as the Kramers–Kronig transformation, were employed to study the susceptibility of the samples to corrosion, at temperatures 293 K and 333 K in 0.4 M H2SO4 solutions. Our results, from all the above analyses, unanimously point to the fact that in the process of enhancing resistance to corrosion, the annealing stage is the most crucial for improving the coating and the crystal structure of the samples and that the adsorption of Mn is not sufficient for the enhancement of the surface layer. Moreover, it was observed that increasing the temperature of the solution decreases the resistance of the samples owing to an increase in the rate of corrosion. تفاصيل المقالة -
حرية الوصول المقاله
2 - On the corrosion resistance of AISI 316L-type stainless steel coated with manganese and annealed with flow of oxygen
Hadi Savaloni Ensieh Agha-Taheri Fateme AbdiAbstractAISI 316L-type stainless steel was coated with 300-nm-thick Mn thin films and post-annealed at 673 K with a constant flow of oxygen (250 cm3/min). The films crystallographic and morphological structures were analyzed using X-ray diffraction (XRD) and atomic forc أکثرAbstractAISI 316L-type stainless steel was coated with 300-nm-thick Mn thin films and post-annealed at 673 K with a constant flow of oxygen (250 cm3/min). The films crystallographic and morphological structures were analyzed using X-ray diffraction (XRD) and atomic force microscopy (AFM) before corrosion test and scanning electron microscopy (SEM) after corrosion test. Corrosion behavior of the samples in 0.3, 0.5 and 0.6 M NaCl solutions was investigated by means of potentiodynamic and electrochemical impedance spectroscopy (EIS) techniques. Results showed that the corrosion inhibition of annealed Mn/SS316L in all NaCl solutions with different concentrations is higher than that of bare SS316L. A correlation is achieved between the structural variation of the films with the potentiodynamic and EIS corrosion results. تفاصيل المقالة -
حرية الوصول المقاله
3 - Anti-corrosion properties of stainless steel 304L coated with Mn-based thin film and annealed with nitrogen flux exposed to saline solution under various temperatures
Farzaneh Modiri Hadi SavaloniAbstractIn this work the corrosion resistance of stainless steel 304L coated with Mn-based thin film and post annealed with flow of nitrogen at 723 K in 0.6 M NaCl solution is reported. The latter was performed at three different solution temperatures of 293 K, 313 K an أکثرAbstractIn this work the corrosion resistance of stainless steel 304L coated with Mn-based thin film and post annealed with flow of nitrogen at 723 K in 0.6 M NaCl solution is reported. The latter was performed at three different solution temperatures of 293 K, 313 K and 333 K. X-ray diffraction analysis was used to determine the crystallographical structure and phases of the annealed samples. Atomic force microscope and field emission scanning electron microscope were employed to determine the morphology of the surface of the samples. Corrosion behavior of the samples in the corroding media was studied by means of electrochemical impedance spectroscopy (EIS) and polarization analysis. Results showed that the sample investigated in the 0.6 M NaCl solution at 293 K temperature has the highest corrosion resistance than those studied at higher temperatures. The correctness of the EIS results was confirmed by Kramers–Kronig transformation, while fitting of the data (Nyquist and Bode diagrams) to suitable equivalent electrical circuits showed that the highest corrosion enhancement is achieved for the Mn-based/SS304L sample in the 0.6 M NaCl solution at 293 K temperature, resulting in a 90.57% corrosion inhibition enhancement factor (η%). Polarization measurements also showed that this sample has the lowest corrosion current density, lowest corrosion rate and highest corrosion potential with a 96% corrosion inhibition efficiency factor (PE%). Consistent results are achieved for EIS and polarization measurements which are then correlated with the nanostructure of the films using X-ray diffraction and atomic force microscope analyses. تفاصيل المقالة -
حرية الوصول المقاله
4 - Growth of carbon nanostructures upon stainless steel and brass by thermal chemical vapor deposition method
Z. Haghparast F. Bisepar S. A. Khorrami Sh. Moradi H. AghaieThe lack of complete understanding of the substrate effects on carbon nanotubes (CNTs) growth poses a lot oftechnical challenges. Here, we report the direct growth of nanostructures such as the CNTs on stainless steel 304and brass substrates using thermal chemical vapor أکثرThe lack of complete understanding of the substrate effects on carbon nanotubes (CNTs) growth poses a lot oftechnical challenges. Here, we report the direct growth of nanostructures such as the CNTs on stainless steel 304and brass substrates using thermal chemical vapor deposition (TCVD) process with C2H2 gas as carbon sourceand hydrogen as supporting gas mixed in Ar gas flow. We used an especial etching of substrates. The catalystsconsist of a thin layer of Cu deposited on substrates. Morphology and structural information about preparedCNTs were provided by scanning electron microscopy (SEM). Results showed that some nanostructures such assingle and multi walled carbon nanotubes (SWCNTs and MWCNTs), bundle (70-80 nm), nano wire (80-100nm) and amorphous carbon were formed on stainless steel 304 as substrate. Moreover, different kind of carbonnanotubes such as MWCNTs (30-50 tun), nano crystalline diamond (10-30 nm), amorphous carbon, roped (70-80 nm) structures with different sizes grew on the brass substrate as well. In conclusion, we suggest thatstainless steel 304 and brass can be replaced with Si/Si02 as substrate in practical applications. تفاصيل المقالة -
حرية الوصول المقاله
5 - Corrosion Inhibition of AISI 304 Stainless Steel using Zinc Nitride Coating
Fatemeh AbdiThe corrosion behavior of Zn/ (AISI304) annealed at different temperatures with flow of nitrogen gas was investigated in the 3.5%NaCl solution. Crystallography structure of the samples was analyzed using X-ray diffraction (XRD) pattern. The results showed that with incr أکثرThe corrosion behavior of Zn/ (AISI304) annealed at different temperatures with flow of nitrogen gas was investigated in the 3.5%NaCl solution. Crystallography structure of the samples was analyzed using X-ray diffraction (XRD) pattern. The results showed that with increasing annealing temperature, the intensities of oxide and nitride phases were increased. Surface morphology of the samples was studied using atomic force microscope (AFM) before corrosion tests. AFM results showed that by increasing annealing temperature, grains become greater that may be the result of heat accumulation, causing higher rate of diffusion in the sample. Electrochemical Impedance spectroscopy (EIS) and Polarization tests were carried out for corrosion resistance investigation of the produced samples. The corrosion results revealed that highest corrosion resistance was achieved for the sample at the highest annealing temperature. For more in depth analysis, the equivalent circuit of samples was obtained, using the EIS data. Finally, the surface of the corroded samples was observed using scanning electron microscopy (SEM). تفاصيل المقالة -
حرية الوصول المقاله
6 - Electrochemical and Theoretical Studies of Adsorption of 1-H-benzotriazole at Stainless Steel in Hydrochloric acid Solution Interface as Corrosion Inhibitors
Nazanin Behineh Mohammad Hossain Zargazi Hesam BaheriThe influence of the concentration of1-H-benzoteriazolon the corrosion of 316 stainless steel (SS) in chloride acid 1M solutions was studied. The potentiodynamics polarization and scanning electron microscopy (SEM) have been used. The inhibition efficiency increased w أکثرThe influence of the concentration of1-H-benzoteriazolon the corrosion of 316 stainless steel (SS) in chloride acid 1M solutions was studied. The potentiodynamics polarization and scanning electron microscopy (SEM) have been used. The inhibition efficiency increased with an increase in the concentration of1-H-benzoteriazol.The adsorption of1-H-benzoteriazol onto the SS surface occurs according to the Langmuirisotherm. The corrosion kinetic parameters of 316 stainless steel and thermodynamicadsorption parameters for1-H-benzoteriazolwere determined and discussed. تفاصيل المقالة -
حرية الوصول المقاله
7 - Effects of Welding Cycles on Microstructural Characteristics and Mechanical Properties of SAF 2507 Super Duplex Stainless Steel
M. A. Beheshty E. H. Dehkordi K. Zarrin Naghsh M. R. B. MarnanyUnique characteristics of SAF 2507 (UNS S32750) super duplex stainless steels alloy such as its high mechanical properties and strong corrosion resistivity behavior led to its widely applications in sea water and other highly corrosive media in oil & gas industries, أکثرUnique characteristics of SAF 2507 (UNS S32750) super duplex stainless steels alloy such as its high mechanical properties and strong corrosion resistivity behavior led to its widely applications in sea water and other highly corrosive media in oil & gas industries, however, its known that it has also got its own drawbacks particularly the impact and consequences that the number of heating/cooling cycles during its welding or welding repairs may have on its functional characteristics. While international standards/codes are not defining any limitation on weld repairs and/or permitted numbers of weld repairs on duplex stainless steel materials, some owners and clients are limiting the number of permitted repairs to maximum two (just to be in safe side) hence always motivating the question if the number of repairs become more than two, whether and how that could affect the microstructural characteristics and mechanical properties of a welded duplex material. This subject has also never been discussed in any of the earlier investigations. The current proposed article scrutinizing the effect of number of welding repairs on functional characteristics of an SAF 2507 welded plate. 4 samples have been welded by GTAW process using rod ER2594 filler metal with 0 to 3 numbers of repairs on them to evaluate the effect of various numbers of heating/cooling cycles caused by different numbers of repairs on the weldment. Mechanical properties and microstructural characteristics of the samples have been analyzed to observe the excessive presence of any detrimental intermetallic phases and also to see whether any changes in the value of mechanical properties have been occurred or not. It has been concluded that the number of weld repairs (up to 3 times as been examined here and even higher) on welded samples has got no (negligible) negative impacts on the strength of weldments or other mechanical / microstructural characteristics of the weldment, if done properly. تفاصيل المقالة -
حرية الوصول المقاله
8 - Comparison of Ultrasonic and Thermal Stress Relief Treatments of GTAW Welded 316L Stainless Steel Pipes on Residual Stress an Stress Corrosion Cracking(SCC)
N ArabInert Gas Tungsten Arc Welding (GTAW) process is one of the most widely used welding processes in which material is prone to stress corrosion cracking (SCC). Stress corrosion indicates cracking due to combined effect of stress and corrosion. Many rupture incidents have أکثرInert Gas Tungsten Arc Welding (GTAW) process is one of the most widely used welding processes in which material is prone to stress corrosion cracking (SCC). Stress corrosion indicates cracking due to combined effect of stress and corrosion. Many rupture incidents have occurred due to this type of cracks. Effect of ultrasonic waves were studied on GTAW welded SS316L metal, in this paper. Two samples were healed by post weld ultrasonic treatment, two samples by post weld heat treatment and two were considered as control samples with no post treatment. Residual stress of all six pieces were measured by XRD method. Afterwards, samples were placed in corrosion environment. Results show that residual stress was decreased to 54.3% using heat treatment whereby this decreased to 58.7% by ultrasonic waves. It was also shown that untreated samples cracked after 720 hours, while no crack was seen in post weld ultrasonic treated samples تفاصيل المقالة -
حرية الوصول المقاله
9 - Effects of Shielding Gas on the Depth, Width and Hardness of 17-4PH Stainless Steel during TIG Welding
S, M Hosseini Farzaneh M BelbasiThe present study investigates the effects of type of shielding gas on the depth, width and hardness of 17-4PH stainless steel. For this purpose, pure He, pure Ar and 80%Ar + 20% He were used as shielding gases in TIG welding of 17-4PH SS. Weld depth and width of specim أکثرThe present study investigates the effects of type of shielding gas on the depth, width and hardness of 17-4PH stainless steel. For this purpose, pure He, pure Ar and 80%Ar + 20% He were used as shielding gases in TIG welding of 17-4PH SS. Weld depth and width of specimens were measured by macro etching. Microstructure of welds was studied by using SEM technique. Moreover, micro Vickers hardness test was accomplished to gauge the hardness of welds. Results showed that specimen welded with pure He has the highest hardness values in the weld zone due to the reduction of δ-ferrite formation in the martensitic matrix. Furthermore, owing to the lower thermal conductivity and heat input of Ar gas, specimen welded by pure Ar has the shallowest and narrowest weld bead. However, due to produce hotter arc by addition of He in shielding gas, enhancements observed in the weld depth and width of specimens welded with pure He and 80%Ar + 20% He. تفاصيل المقالة -
حرية الوصول المقاله
10 - Effects of Shielding Gas on the Mechanical and Microstructural Properties of 409L Ferritic Stainless Steels during Gas Metal Arc Welding
A. Feghhi A. Emamikhah Y. Bayat AslThe present study investigates the effects of type of shielding gas on the weld microstructure and mechanical properties of 409L ferritic stainless steel. For this purpose, Ar, Ar +20% He, Ar + 12% CO2, and Ar + 25% CO2 were used as shielding gases in gas metal arc weld أکثرThe present study investigates the effects of type of shielding gas on the weld microstructure and mechanical properties of 409L ferritic stainless steel. For this purpose, Ar, Ar +20% He, Ar + 12% CO2, and Ar + 25% CO2 were used as shielding gases in gas metal arc welding (GMAW) of stainless steel. To evaluate the welds, non-destructive inspections of the specimens were followed by mechanical (hardness and tensile) tests while microstructural examinations of both the heat affected zone (HAZ) and the fusion zone were performed. Moreover, the phases produced were observed and identified by analyzing the specimens using SEM and EDS techniques. Results showed that specimens welded with Ar + 25% CO2 and Ar + 12% CO2 have the highest strength and hardness values in the fusion zone due to the formation of martensite around the ferrite grains. However, the enhancements observed in the mechanical properties of specimens welded with Ar and Ar +20% He were attributed to the reduced ferrite grain size and martensite content تفاصيل المقالة -
حرية الوصول المقاله
11 - Weldability of Dissimilar Joint of AISI 304 to CK45 by GTAW Method
A. Taherkhani Y. Shajari K. Mirzavand A. Mellatkhah Z. S. SeyedraoufiJoint of dissimilar steels is widely used in the chemical, food, oil, water and sewage industries. In the meantime, the joint of carbon steels to austenitic stainless steels is important with the GTAW welding process. In this paper, weldability of 304 stainless steel to أکثرJoint of dissimilar steels is widely used in the chemical, food, oil, water and sewage industries. In the meantime, the joint of carbon steels to austenitic stainless steels is important with the GTAW welding process. In this paper, weldability of 304 stainless steel to CK45 carbon steel by GTAW method according to the filler metal parameter has been investigated. Welding of the samples was performed via gas tungstenarc welding (GTAW)method using 3 types of ER308L, ER310, and ER316L metal filler. Tensile test was done to evaluate the joint weldability. The microstructure of the samples was also studied using OM and FE-SEM microscopes. In the tensile test, the welded sample with ER308L electrode was fractured from HAZ area close to Ck45 base metal. Microstructure investigations showed that the best structural quality in this joint is the achievement of the stable austenite with a low amount of ferrite when using ER308L metal filler, and the worst structure was related to the use of ER310L metal filler that completely austenite structure with crack in the weld metal area was created. The results of tensile test showed that the maximum yield strength and tensile strength is achieved 382 MPa and 675 MPa using ER308L metal filler, respectively. تفاصيل المقالة -
حرية الوصول المقاله
12 - The Effect of Focal Distance and Type of Auxiliary Gas on Cut Width in CO2 Laser Cutting of Stainless and Mild Steel Sheets
Hossein Taheri Hamid Zarepour Firouzabadi Majid HashemzadehLens focal distance and auxiliary gas type utilized in CO2 laser cutting are two important parameters affecting process measures such as cuts width and quality at desired cutting speeds. This research work focuses on cuts width and quality in CO2 laser cutting with a po أکثرLens focal distance and auxiliary gas type utilized in CO2 laser cutting are two important parameters affecting process measures such as cuts width and quality at desired cutting speeds. This research work focuses on cuts width and quality in CO2 laser cutting with a power of 4000W on two types of steel sheets at different focal distance values and using different types of auxiliary gas. The effect of focal distances of 5” and 7.5” as well as utilizing oxygen and nitrogen as auxiliary gas on cut width and quality in 304L stainless steel and St37 steel sheets were investigated. The size of cut widths was measured using an optical microscopy. The results demonstrate that cuts performed at the focal distance of 7.5” are wider than those created at the focal distance of 5”. It is also observed that with increased workpiece thickness, the use of focal distance of 7.5” is more feasible because cuts are faster; need lower laser power, and use less amount of auxiliary gas. When using oxygen as auxiliary gas, the main factor affecting the cutting efficiency is the oxidation reaction, whereby oxidation energy is added to laser power which results to an increased energy level in the cutting region. This means that using oxygen as auxiliary gas makes it possible to cut thicker sheets at higher cutting speeds as compared to that of nitrogen. However, when using oxygen as auxiliary gas, the quality of cuts appears to be lower and their width larger as compared to cuts performed by nitrogen auxiliary gas. تفاصيل المقالة -
حرية الوصول المقاله
13 - Investigation of Compressive Stresses of Stainless Steel 316L Diamond Lattice Structures Under the Effect of Spherical Connections Produced by SLM Additive Manufacturing
Behnam Ahmadi Roozbahani AliAkbar Lotfi NeyestanakIn this study, the compressive stresses of dodecahedron diamond lattice structures have been investigated. The finite element method has been used for Stress analysis. After the simulation, it was found that more stresses are applied at the junction of the struts of thi أکثرIn this study, the compressive stresses of dodecahedron diamond lattice structures have been investigated. The finite element method has been used for Stress analysis. After the simulation, it was found that more stresses are applied at the junction of the struts of this structure due to the application of compressive force. For this purpose, the connection point of the structure’s struts was strengthened by spherical connections, and a new type of dodecahedron structure was created. The validation and effect of spherical connections in compressive stresses have been evaluated experimentally. Two types of diamond lattice structures are made of stainless steel 316L by the SLM method. The results show that in the same condition, the use of spherical connections with twice the diameter of the structure’s struts helps to strengthen the structure and increase its compressive strength by 18% compared to the simple structure. تفاصيل المقالة -
حرية الوصول المقاله
14 - Energy-Based Prediction of Low-Cycle Fatigue Life of CK45 Steel and SS316 Stainless Steel
M Shariati H MehrabiIn this paper, low cycle fatigue life of CK45 steel and SS316 stainless steel under strain-controlled loading are experimentally investigated. In addition, the impact of mean strain and strain amplitude on the fatigue life and cyclic behavior of the materials are studie أکثرIn this paper, low cycle fatigue life of CK45 steel and SS316 stainless steel under strain-controlled loading are experimentally investigated. In addition, the impact of mean strain and strain amplitude on the fatigue life and cyclic behavior of the materials are studied. Furthermore, it is attempted to predict fatigue life using energy and SWT damage parameters. The experimental results demonstrate that increase in strain amplitude decreases fatigue life for both materials, strain amplitude has a remarkable effect on fatigue life, and the impact of mean strain is approximately negligible. Furthermore, the energy damage parameter provides more accurate prediction of fatigue life for both materials. تفاصيل المقالة -
حرية الوصول المقاله
15 - Non-Axisymmetric Time-Dependent Creep Analysis in a Thick-Walled Cylinder Due to the Thermo-mechanical loading
M Moradi A LoghmanIn this study, the non-linear creep behaviour of a thick-walled cylinder made of stainless steel 316 is investigated using a semi-analytical method. The thick-walled cylinder is under a uniform internal pressure and a non-axisymmetric thermal field as a function of the أکثرIn this study, the non-linear creep behaviour of a thick-walled cylinder made of stainless steel 316 is investigated using a semi-analytical method. The thick-walled cylinder is under a uniform internal pressure and a non-axisymmetric thermal field as a function of the radial and circumferential coordinates. For the high temperature and stress levels, creep phenomena play a major role in stress redistributions across the cylinder thickness. The Bailey-Norton creep constitutive equation is used to model the uniaxial creep behaviour of the material. Creep strain increments are accumulated incrementally during the life of the vessel. Creep strain increments are related to the current stresses and the material uniaxial creep model by the well-known Prandtl-Reuss relations. Considering the mentioned non-axisymmetric boundary conditions, the heat conduction equation and the Navier partial differential equations has been solved using the separation of variables and the complex Fourier series methods. The corresponding displacement, strain and stress functions are obtained. Considering the non-axisymmetric loadings, the distribution of the radial, circumferential and shear stresses are studied. Furthermore, the effects of internal pressure and external temperature distribution on the effective stress history are investigated. It has been found that the non-axisymmetric thermal loading has a significant effect on stress redistributions. تفاصيل المقالة -
حرية الوصول المقاله
16 - بررسی افزایش سختی سطح فولاد ضد زنگ 316 کم کربن با استفاده از پوشش آلومینیم فسفات آمورف
تارا بازدار عبدالمجید اسلامی احمد منشی فاطمه سادات سیدان علیرضا عباسلودر این تحقیق روکش آلومینیم فسفات آمورف بر روی سطح فولاد ضد زنگ ۳۱۶ کم کربن برای افزایش سختی و مقاومت شیمیایی اعمال گردید. آمورف بودن به معنی نداشتن ساختار کریستالی و مرز دانه در نتیجه نداشتن ضعفهای مربوط به این دو پارامتر است. در این سنتز از محلولهای پیشساز آلومینیم ن أکثردر این تحقیق روکش آلومینیم فسفات آمورف بر روی سطح فولاد ضد زنگ ۳۱۶ کم کربن برای افزایش سختی و مقاومت شیمیایی اعمال گردید. آمورف بودن به معنی نداشتن ساختار کریستالی و مرز دانه در نتیجه نداشتن ضعفهای مربوط به این دو پارامتر است. در این سنتز از محلولهای پیشساز آلومینیم نیترات نه آبه و پنتاکسیدفسفر در اتانول استفاده شد. 15 دقیقه تا دمای ۷۰ درجه سانتیگراد حرارت داده شد تا سل شفافی با ۷۵ درصد وزنی آلومینیم فسفات و نسبت مولی آلومینیم به فسفر ۷۵/۱ حاصل شود. بعد از اجرای عمل فعالسازی سطح صفحات فولادی و غوطه وری در سل آلومینیم فسفات در سه مرحله یک دقیقه ای به مدت ۲۴ ساعت در ۶۵ درجه سانتیگراد خشک و ۳۰ دقیقه در ۵۰۰ درجه سانتیگراد حرارت دهی شد. الگوی تفرق اشعه ایکس وجود هلال فاز آمورف را نشان دادکه با مقداری آلومینیم اضافی کنترل میشود. تصاویر میکروسکوب الکترونی روبشی و آنالیز طیف سنجی نشان داد که کنده شدن روکش در نمونه های فعال شده با ماربل بهتر از آکوارجیا و لوریا میباشد. آزمون میکروسختی بر روی نمونه عملیات حرارتی شده در ۵۰۰ درجه سانتیگراد حاکی از افزایش حدود سه برابری سختی در مقایسه با فلز زیر لایه بود. تفاصيل المقالة -
حرية الوصول المقاله
17 - ارزیابی حساسیت به ترک گرم و خواص مکانیکی فلز جوش ER310 در اتصالات جوش فولاد زنگنزن 304 با اعمال لرزش الکترومغناطیس
محمد امین قدم دزفولی رضا دهملایی سید رضا علوی زارعدر این پژوهش تأثیر اعمال لرزش الکترومغناطیس همزمان با جوشکاری بر ریزساختار، خواص مکانیکی و حساسیت به ترک گرم فولاد زنگنزن 304 مورد مطالعه قرار گرفته است. جوشکاری با روش GTAW و با فلز پرکننده آستنیتی ER310 تحت اعمال لرزش الکترومغناطیس با ولتاژهای مختلف انجام گردید. بررسی أکثردر این پژوهش تأثیر اعمال لرزش الکترومغناطیس همزمان با جوشکاری بر ریزساختار، خواص مکانیکی و حساسیت به ترک گرم فولاد زنگنزن 304 مورد مطالعه قرار گرفته است. جوشکاری با روش GTAW و با فلز پرکننده آستنیتی ER310 تحت اعمال لرزش الکترومغناطیس با ولتاژهای مختلف انجام گردید. بررسیهای ریزساختاری با استفاده از میکروسکوپهای نوری و الکترونی روبشی SEM انجام شد. خواص مکانیکی اتصال با آزمونهای ضربه و سختی سنجی و حساسیت به ترک گرم با آزمون وارسترینت طولی ارزیابی گردید. مطالعات ریزساختاری نشان داد که اعمال لرزش الکترومغناطیس باعث ریزتر شدن ریزساختار فلز جوش و تغییر حالت انجمادی از دندریتی ستونی درشت به دندریتی هممحور گردیده است. دلیل تغییر حالت انجمادی، ریز شدن ریزساختار ناشی از شکسته شدن نوک دندریتهای در حال رشد و افزایش مراکز جوانهزنی غیر همگن در مذاب و در نتیجه افزایش تعداد جوانهها در حین انجماد مذاب جوش تشخیص داده شد. نتایج نشان داد که در اثر اعمال لرزش الکترومغناطیس انرژی ضربهای از 104 به 165 ژول و سختی از 230 به 253 ویکرز در فلز جوش افزایش یافته است. نتایج آزمون وارسترینت طولی نشان داد که اعمال لرزش باعث کاهش حساسیت به ترک گرم در فلز جوش گردیده است و مجموع طول ترک از 8/18 میلیمتر در نمونه بدون لرزش به 3/8 میلیمتر در نمونه تحت لرزش 30 ولت کاهش پیدا کرده است. تفاصيل المقالة -
حرية الوصول المقاله
18 - شبیه سازی تاثیر لقی بین سنبه و ماتریس بر حد نسبت کشش در فرآیند کشش عمیق فولاد زنگ نزن
علی فتحی جوکندان مهرداد عضو امینیانکشش عمیق یکی از مهمترین فرآیندهای شکل دادن ورق های فلزی در صنعت می باشد که در آن یک ورق مسطح توسط سنبه به درون حفره ماتریس کشیده شده و شکل سنبه را به خود می گیرد. یکی از پارامترهای مهم در فرآیند کشش عمیق لقی بین سنبه و ماتریس می باشد که تاثیر بسزایی در حد نسبت کشش داشته أکثرکشش عمیق یکی از مهمترین فرآیندهای شکل دادن ورق های فلزی در صنعت می باشد که در آن یک ورق مسطح توسط سنبه به درون حفره ماتریس کشیده شده و شکل سنبه را به خود می گیرد. یکی از پارامترهای مهم در فرآیند کشش عمیق لقی بین سنبه و ماتریس می باشد که تاثیر بسزایی در حد نسبت کشش داشته و برای تولید اشکال پیچیده حائز اهمیت می باشد. یک ابزار مفید برای مطالعه این فرآیند و تاثیر پارامتر های موثر بر آن روش اجزاء محدود است. در این تحقیق اثر لقی بین سنبه و ماتریس بر حد نسبت کشش بررسی شد. و مشخص گردید که از میان لقی های انتخاب شده لقی 9/0 میلی متر مناسب ترین لقی برای ورق با ضخامت 6/0 میلی متر می باشد و با کاهش این لقی در 66/0 میلی متر حد نسبت کشش قطعه نیز کاهش خواهد یافت. تفاصيل المقالة -
حرية الوصول المقاله
19 - Electrochemical and Tribological Behaviour of Oxide Dispersion Strengthened Duplex Stainless Steel in Mine Water Environment
oladayo olaniranAbstract This work investigated the electrochemical and aqueous tribological behavior of hot pressed 2205 duplex stainless steel (DSS). DSS sintered composites of different volume percent (% vol) of partially stabilized zirconia (PSZ) was developed using powder metallur أکثرAbstract This work investigated the electrochemical and aqueous tribological behavior of hot pressed 2205 duplex stainless steel (DSS). DSS sintered composites of different volume percent (% vol) of partially stabilized zirconia (PSZ) was developed using powder metallurgy (PM) technique. Electrochemical behaviour was studied at room temperature, using open circuit potential and potentiodynamic scanning in simulated mine water and 3.5% NaCl solution while aqueous tribological test was carried out in simulated mine water. The influence of PSZ, Cr and Ni additions on the degradation mechanisms of corrosion and wear of the modified DSS were evaluated. X-Ray Microtomography (XRM) was used as experimental technique for defect analysis from the corrosion studies. Results show the surface imaging capability of SEM and the internal structures imaging capability of XRM. SEM revealed important surface degradation mechanisms of the materials whilst relevant information on pitting corrosion was obtained from XRM. It was deduced that, pitting corrosion can be caused by the growth of intergranular corrosion resulting from the attack and the breakdown of passive films by chloride ions which affected both the surface and the internal parts of the samples. تفاصيل المقالة -
حرية الوصول المقاله
20 - Fabrication and Characterization of Nanostructure Functionally Graded Ni-P Electroless Coating
Sayede Razieh Anvari Sayed Mahmoud Monirvaghefi Mohammad Hossein EnayatiIn this research, novel functionally graded Ni-P coating was deposited with electroless process. The content of phosphorus was controlled to change gradual through the thickness of the coating. During the plating, bath temperature and pH were changed at specified interv أکثرIn this research, novel functionally graded Ni-P coating was deposited with electroless process. The content of phosphorus was controlled to change gradual through the thickness of the coating. During the plating, bath temperature and pH were changed at specified intervals to obtain functionally graded structure. To compare the properties of functionally graded coating with Ni-P single-layer coatings, three types of coatings with different phosphorus contents were also deposited. Microstructure and phase composition of coatings were studied by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffractometry (XRD). The mechanical properties and tribological behavior of coatings were also investigated. Low phosphorus and medium phosphorus single-layer coatings had fully crystalline and amorphous-crystalline structures, respectively. While high phosphorus coating appeared to have a fully amorphous structure. TEM images showed that low phosphorus coating had nano-crystalline structure. Results of nano-indentation test showed gradual changes in hardness profile in cross-section of functionally graded coating due to the gradual changes of phosphorus content in the thickness of this coating. According to the wear test data, medium phosphorus coating had minimum wear resistance. Functionally graded coatings had better wear resistance than single-layer coatings. تفاصيل المقالة -
حرية الوصول المقاله
21 - Isothermal and cyclic oxidation behavior of AISI 430 ferritic stainless steel coated with titanium
Saeed Keshavarz Morteza Zandrahimi Hadi EbrahimifarIn order to improve the oxidation resistance of ferritic stainless steel, it is possible to deposit a protective coating on steel substrate. In this research through the usage of pack cementation method a coating of titanium was applied on the surface of AISI 430 stainl أکثرIn order to improve the oxidation resistance of ferritic stainless steel, it is possible to deposit a protective coating on steel substrate. In this research through the usage of pack cementation method a coating of titanium was applied on the surface of AISI 430 stainless steel. Scanning Electron-Microscopy (SEM), Energy- Dispersive X-ray spectrometry (EDAX) and X-ray diffraction (XRD) were used for evaluating of coating structure. Results showed that titanium coating consisted of two layers with the total thickness of 50 micron. The titanized layer consisted of TiFe, TiFe2 and Fe2TiO5 phases. For investigating the oxidation behavior of coated and uncoated specimens, isothermal and cyclic oxidation tests were performed at 1000 C. In isothermal oxidation, the oxidation resistance of the titanium coated specimens was improved by restricting the outward penetration of chromium cation. The results of cyclic oxidation of titanium coated samples indicated that they were resistance to lamination and cracking. تفاصيل المقالة -
حرية الوصول المقاله
22 - Characterization of SiO2-TiO2 Coatings on 316l Stainless Steel Substrates
Manuel Gutierrez Martinez Lizangela Guerra Barbara Bermudez Reyes Roberto Cabriales Luis ReyesThis paper reports nano-structured SiO2-TiO2 coatings using the sol-gel technique on 316L steel substrates. Nanoindentation, surface analysis and corrosion resistance tests were performed on different samples. The nanomechanical tests allowed to compare uncoated steel s أکثرThis paper reports nano-structured SiO2-TiO2 coatings using the sol-gel technique on 316L steel substrates. Nanoindentation, surface analysis and corrosion resistance tests were performed on different samples. The nanomechanical tests allowed to compare uncoated steel samples (Eavg = 193.24 GPa and mean hardness of 2.63 GPa and coated steel samples (Eavg = 287.38 GPa and mean hardness of 5.74 GPa), resulting into an improvement of the resistance and modulus of elasticity on the coated steel substrates. From a surface analysis an average thickness of 1.12 μm was obtained in the coated samples, presenting a dense and consolidated coating. Polarization resistance (PR) and electrochemical impedance spectroscopy (EIS) tests were performed. The PR tests showed a resistance of 2.11 105 (Ω cm2) for the uncoated steel, while the coated steel showed a resistance of 3.46 105 (Ω cm2), observing an increase in resistance compared to bare steel. The EIS tests showed greater resistance by the coated steel (5.8 105 (Ω cm2)) compared to the bare steel (2.8 105 (Ω cm2)). The effects of the electrolyte in both conditions were observed by SEM after immersion for 24 hours, showing pitting by the bare steel and good protection by the coated steel. تفاصيل المقالة -
حرية الوصول المقاله
23 - The Effect of Friction Stir Processing Speed Ratio on the Microstructure and Mechanical Properties of A 430 Ferritic Stainless Steel
Ali Salemi Golezani S. M Arab Sh. Javadi Firooz KargarThis study is an attempt to investigate the effect of welding rotational and traverse speed on mechanical and microstructural properties of A 430 stainless steel in order to give an effective processing window to achieve an appropriate microstructure and so mechanical p أکثرThis study is an attempt to investigate the effect of welding rotational and traverse speed on mechanical and microstructural properties of A 430 stainless steel in order to give an effective processing window to achieve an appropriate microstructure and so mechanical properties. There are a wide range industrial uses for ferritic stainless steel. There from they have some problems like grain coarsening and martensitic transformation during conventional fusion welding, solid state welding methods has found a great interest. A heavy duty NC machine is used for FSW. Water cooled brass chamber is used to prevent the tool from severe wear and damage. In order to study the effect of rotational to welding speed ratio ( ) on microstructure, rotational speeds of 600, 800 rpm and welding speeds of 50, 100, 150, 200 mm/min with a spindle tilt angle of 3° are selected. Results showed that ferrite grain size decreased by increasing welding speed at constant rotational speeds which prove dynamic recrystallization occurrence in the nugget zone. Mechanical tests showed that strength and hardness of weld zone in increased compared to base metal. تفاصيل المقالة -
حرية الوصول المقاله
24 - Semiconducting properties of passive films formed on AISI 420 stainless steel in nitric acid solutions
Arash Fattah-alhosseini Mohammad Mehdi KhalvanThis study focuses on the semiconductor properties of passive films formed on AISI 420 stainless steel immersed in four nitric acid solutions under open circuit potential (OCP) conditions. For this purpose, the passivation parameters and semiconductor properties of pass أکثرThis study focuses on the semiconductor properties of passive films formed on AISI 420 stainless steel immersed in four nitric acid solutions under open circuit potential (OCP) conditions. For this purpose, the passivation parameters and semiconductor properties of passive films were derived from potentiodynamic polarization and Mott–Schottky analysis, respectively. The OCP plots showed that the open circuit potential of AISI 420 stainless steel is directed towards positive amount, which are indicative of the formation of passive film and its role in increasing protectivity with time. The potentiodynamic polarization results showed that the corrosion current density of AISI 420 stainless steel increased with the increase in the concentration of solutions. Mott–Schottky analysis revealed that the existence of a duplex passive film structure composed of two oxide layers of distinct semiconductivities (n-type and p-type). Also, Mott–Schottky analysis indicated that the donor densities are in the range 1021 cm-3 and increased with solution concentration. تفاصيل المقالة -
حرية الوصول المقاله
25 - The Weldability Evaluation of Dissimilar Welds of AISI 347 Stainless Steel to ASTM A335 Low Alloy Steel by Gastungesten Arc Welding
Iman Hajiannia Morteza Shamanian Masoud KasiriIn the present study, the Weldability and microstructure of dissimilar welds of AISI 347austenitic stainless steel to ASTM A335 low alloy steel was investigated. For this purpose, gas tungsten arc welding process and two filler metals including ERNICr-3 and ER309L were أکثرIn the present study, the Weldability and microstructure of dissimilar welds of AISI 347austenitic stainless steel to ASTM A335 low alloy steel was investigated. For this purpose, gas tungsten arc welding process and two filler metals including ERNICr-3 and ER309L were used. After welding, the microstructure of the different zones of each joint, including weld metals, heat affected zone (HAZ) 1, inter face and unmixed zones (UMZ) 2 were evaluated by using optical microscopy. The scanning electron microscopy (SEM) 3 equipped to energy disperse spectrometry (EDS) 4 was used to investigate the precipitates, in order to predict the micro structure of the weld metal and transmission zone in dissimilar joints. In ERNiCr-3 weld metal, the solidification was observed as the completely austenitic and equiaxed dendrite5 which contains the precipitates of carbide complex, and also Niobium segregation was happened in the inter dendrite zones. 309L weld metal was observed as the primary ferrite with austenitic matrix and also microstructure was seen as skeletal ferrite morphology. The epitaxial growth was observed in interface between 347austenitic stainless steel and two filler metals and a narrow zone was observed in interface between A335low alloy steel and filler metals, and also the coarse grains occurred in HAZ zone of both weld metals. Finally, it can be denoted that for the joints between the AISI 347 austenitic stainless steel and A335low alloy steel, by the ERNICr-3 filler material provides the optimum qualities. تفاصيل المقالة -
حرية الوصول المقاله
26 - Effect of Thermomechanical Processing on the Microstructure and Mechanical Properties of a Duplex Stainless Steel
Maryam Mohammad Jafarpour Bitollah EghbaliDuplex stainless steels (DSSS) have a microstructure composed of ferrite and austenite phases that gives them a very good combination of mechanical and corrosion properties. These steels are desirable for many applications in the chemical and petrochemical industries. I أکثرDuplex stainless steels (DSSS) have a microstructure composed of ferrite and austenite phases that gives them a very good combination of mechanical and corrosion properties. These steels are desirable for many applications in the chemical and petrochemical industries. In the present study, a type of stainless steel was cast, solution annealed at 1200°C for 60 min and then quenched in water. Initial microstructure was composed of about 51.8% ferrite and 48.1% austenite. The steel was then cold rolled about 90% and subsequent annealing at 800,850 and 900°C for different time were performed. Results showed that tensile strength of steel have been significantly improved. Austenite grain size of cast steel was refined through static recrystallization of the austenite occurred during post cold deformation annealing. Results show that yield strength of as-cast steel is increased from 552 to 1800 and its tensile strength increased from 672 to 2350 MPa as a result of large cold deformation. With increasing annealing time, sigma phase increases and this leads to decrease of elongation. Thus sigma phase can be expected to embitter the alloy. تفاصيل المقالة -
حرية الوصول المقاله
27 - Dissimilar resistance spot welding of AISI 1075 eutectoid steel to AISI 201 stainless steel
Mehdi Safari Hossein MostaanIn this paper, dissimilar resistance spot welding of AISI 1075 eutectoid steel to AISI 201 stainless steel is investigated experimentally. For this purpose, the experiments are designed using response surface methodology and based on four-factor, five-level central comp أکثرIn this paper, dissimilar resistance spot welding of AISI 1075 eutectoid steel to AISI 201 stainless steel is investigated experimentally. For this purpose, the experiments are designed using response surface methodology and based on four-factor, five-level central composite design. The effects of process parameters such as welding current, welding time, cooling time and electrode force are investigated on the tensile-shear strength of resistance spot welds. The results show that tensile-shear strength of spot welds is increased with increase in the welding current and welding time. Also, it is concluded from results that with increasing the electrode force and cooling time, tensile-shear strength of welded joints is decreased. During tensile-shear tests, three failure modes are observed, namely interfacial, partial pullout and pullout modes. The analysis of variance for the tensile-shear strength indicates that the main effects of welding current, electrode force, welding time, cooling time, second- order effect of the welding current and cooling time, two level interactions of welding current with welding time, welding current with cooling time and electrode force with cooling time are significant model terms. The results of analysis of variance show that the presented model for tensile-shear strength of dissimilar resistance spot welds of AISI 1075 eutectoid steel to AISI 201 stainless steel can predict 95.00% of the experimental data and leave only 5.00% of the total variations as unexplained. تفاصيل المقالة -
حرية الوصول المقاله
28 - Microstructure and Mechanical Properties of the Friction Welded Joint between X53CrMnNiN219 and X45CrSi93 Stainless Steel
khalil gheisari Mohammad Reza AbasiDissimilar metals friction welding of austenitic–martensitic stainless steels is commonly used in order to manufacture engine valves in the automobile industry. In this study, X53CrMnNiN219 (austenitic stainless steel) and X45CrSi93 (martensitic stainless steel) v أکثرDissimilar metals friction welding of austenitic–martensitic stainless steels is commonly used in order to manufacture engine valves in the automobile industry. In this study, X53CrMnNiN219 (austenitic stainless steel) and X45CrSi93 (martensitic stainless steel) valve steel rods were welded by friction welding process. The welded joint was then heat treated at 760 0C for 60 min. Mechanical properties of the welded and heat treated samples were identified by means of microhardness and tensile tests. The microstructure of the weld and the fracture surface of the tension samples were investigated by optical microscopy and scanning electron microscopy. Fractographic evaluations also were performed by using scanning electron microscopy. According to the findings, due to the higher thermal conductivity and lower strength of the martensitic stainless steel, a larger upset and a broader heat affected zone is observed in the martensitic side. Furthermore, formation of non-tempered martensite with the maximum hardness of 880 HV in the heat affected zone (HAZ) of the martensitic stainless steel side makes as-welded material susceptible to brittle fracture as detected by fractographic examinations. Nevertheless, a successfully transition from brittle to ductile behavior is observed by the post-weld heat treatment at 760 0C for 60 min. تفاصيل المقالة -
حرية الوصول المقاله
29 - Experimental Investigation on the dissimilar laser weld joints between Inconel 625 Superalloy and AISI 430 Ferritic Stainless Steel
Hossein Mostaan Mahdi Rafiei Mohammad EmadiMechanical properties optimization of weldment such as tensile strength, microhardness and impact toughness are of prime importance in welding technology. The main aim of this research is to investigate the microstructural evolutions and also optimization of tensile str أکثرMechanical properties optimization of weldment such as tensile strength, microhardness and impact toughness are of prime importance in welding technology. The main aim of this research is to investigate the microstructural evolutions and also optimization of tensile strength in dissimilar laser welding between Inconel 625 superalloy and AISI 430 ferritic stainless steel. It was found from the microhardness measurements that the hardness is increased form AISI 430 base metal toward Inconel 625 superalloy. This can be attributed to the inherent higher hardness of Inconel 625 and formation of very fine structure and also fine precipitations in the weld metal which are distributed uniformly. Formation of very fine structure and precipitations is due to the rapid cooling rate of the weld metal during laser welding process. Design of experiment based on the response surface method was used in order to optimize the tensile strength of the weld joints. Three process parameters i. e. pulse duration, lamping current and also travel speed were chosen as the main parameters which are considerably affecting the tensile strength of the weld joint. It was found that the lamping current has a higher impact on the tensile strength of the weld joints. تفاصيل المقالة -
حرية الوصول المقاله
30 - The Effect of Reverse Pulse Plating and Lanthanum Addition in Plating Bath on Corrosion Resistance of Austenitic Steel in Chlorine Solution
Leila Bakhtiari Abdolhamid Jafari Shahriyar SharafiThe 316L nickel-chrome molybdenum austenitic stainless steel is commonly employed in various industries. This type of steel is particularly of interest in chemical industries, especially in harsh and corrosive environmental conditions. Although 316L stainless steel has أکثرThe 316L nickel-chrome molybdenum austenitic stainless steel is commonly employed in various industries. This type of steel is particularly of interest in chemical industries, especially in harsh and corrosive environmental conditions. Although 316L stainless steel has good mechanical and corrosive characteristics, it fails to perform well in chlorine-containing aqueous environments. To overcome this issue, a Ni-La-Cr-Fe layer is applied to the 316L steel using the electroplating method. In addition, the reverse pulse plating method is used to control the ion deposition kinetics. The plating current application duration (on-time), the current disruption duration (off-time), and (TRev) are the control parameters of the duration and polarity of the pulse. Finally, the coated layer acquires an average thickness of 6.83 after applying on-time and off-time repeatedly and performing SEM and polarization tests in 1.5% solution at 50 Celcius degrees. Furthermore, the desired surface morphology is achieved, and corrosion resistance is 160 times higher than 316 bare steel. Applying the reverse pulse plating method, adding beneficial compounds of saccharin and SDS, and using lanthanum chloride in the plating bath are the essential reasons to successfully add a coating layer on the 316 bare steel. تفاصيل المقالة -
حرية الوصول المقاله
31 - An investigation on metallurgical and mechanical properties of vacuum brazed Ti-6Al-4V to 316L stainless steel using Zr-based filler metal
M.E Bajgholi R Soltani Tashi A.A Akbari Mousavi E Heshmat DehkordiBoth Ti-6Al-4V and 316L stainless steels are widely used as engineering alloys. Fusion welding of these two alloys is not easily possible due to their incomplete solubility in each other. Brazing is one of the best choices for joining dissimilar alloys. In this study, w أکثرBoth Ti-6Al-4V and 316L stainless steels are widely used as engineering alloys. Fusion welding of these two alloys is not easily possible due to their incomplete solubility in each other. Brazing is one of the best choices for joining dissimilar alloys. In this study, wettability experiments were done at 940 and 970 ºC for 5, 15 and 30 min. Also, joining of these two alloys was carried out at 940 and 970 ºC for 15 min. Optical and scanning electron microscope (SEM) were used for metallurgical observations. Moreover, mechanical properties of the brazed joint were investigated using microhardness test. The results showed that some reaction layers were composed in the brazed joint’s cross section. Ni-Ti intermetallic compounds were also observed in the brazed joint. Investigation of mechanical properties showed that hardness in the joint’s center is higher than base metals. تفاصيل المقالة -
حرية الوصول المقاله
32 - Vacuum Brazing of Zirconium-Based Alloy and 321 Stainless Steel Using Titanium Based Filler Metal
M.E Bajgholi E Heshmat DehkordiBoth Zirconium-based alloys and 321stainless steel are widely used as engineering alloys due to their good mechanical properties. Conventional fusion welding techniques for Zr alloys and stainless steel are not feasible due to the formation of brittle intermetallic comp أکثرBoth Zirconium-based alloys and 321stainless steel are widely used as engineering alloys due to their good mechanical properties. Conventional fusion welding techniques for Zr alloys and stainless steel are not feasible due to the formation of brittle intermetallic compounds such as (Zr3Fe, ZrFe2 and Zr2Fe) and corrosion cracking. Brazing is one of the most widely used techniques for joining dissimilar alloys.Using titanium base filler metal decreases the diffusion and the formation of brittle intermetallic compounds. In this study, wetting experiments were done at 820, 850, 865ºC and 3, 5, 7 and 10 min. Also, joining of these two alloys was carried out at 850 and 865ºC for 10 and 15 minutes. Optical microscope, scanning electron microscope (SEM), XRD, shear test and micro-hardness test were used for metallurgical and mechanical investigations. The results show that 20 ºC/min heating and cooling rates at 850ºC and 10 min brazing condition lead to a proper joint without any brittle intermetallic compounds. تفاصيل المقالة -
حرية الوصول المقاله
33 - The effect of activating fluxes on 316L stainless steel weld joint characteristic in TIG welding using the Taguchi method
E Ahmadi A.R EbrahimiGas tungsten arc welding is fundamental in those industries where it is important to control the weld bead shape and its metallurgical characteristics. However, compared to the other arc welding process, the shallow penetration of the TIG welding restricts its ability t أکثرGas tungsten arc welding is fundamental in those industries where it is important to control the weld bead shape and its metallurgical characteristics. However, compared to the other arc welding process, the shallow penetration of the TIG welding restricts its ability to weld thick structures in a single pass (~ 2 mm for stainless steels), thus its productivity is relativity low. This is why there have been several trials to improve the productivity of the TIG welding. The use of activating flux in TIG welding process is one of such attempts. In this study, first, the effect of each TIG welding parameters on the weld’s penetration depth was shown and then, the optimal parameters were determined using the Taguchi method with L9 (34) orthogonal array. SiO2 and TiO2 oxide powders were used to investigate the effect of activating flux on the TIG weld penetration depth and mechanical properties of 316L austenitic stainless steel. A camera was used to observe and record images of the welding arc, and analyze the relationship between increasing the penetration depth and arc profile. The experimental results showed that activating flux aided TIG welding has increased the weld penetration, tending to reduce the width of the weld bead. The SiO2 flux produced the most noticeable effect. Furthermore, the welded joint presented better tensile strength and hardness. تفاصيل المقالة -
حرية الوصول المقاله
34 - Influence of Initial Microstructure on Hot Deformation Behavior of Duplex Stainless Steels
M Pouyamanesh B Eghbali Gh. R Ebrahimi M SaadatiIn this research the effect of initial microstructure on hot deformation behavior in terms of Ferrite-to-Austenite ratios is studied. Two types of stainless steels C1 and C2 were homogenizing heat-treated and deformed under hot compression examinations at temperatures 9 أکثرIn this research the effect of initial microstructure on hot deformation behavior in terms of Ferrite-to-Austenite ratios is studied. Two types of stainless steels C1 and C2 were homogenizing heat-treated and deformed under hot compression examinations at temperatures 900ºC and 1100ºC at strain rate of 0.1s-1. The results showed that the flow stress levels of specimens are strongly related to deformation parameters and initial microstructures of steels. Moreover, during cooling from 1350ºC to the deformation temperature, flow stress level increased for both samples because of increment in austenite content. تفاصيل المقالة -
حرية الوصول المقاله
35 - The Milling of Metalsthrough Adaptive Neuro-FuzzyInference System (ANFIS) for non-touch Measuring of the Temperature to Reduce Coolant
Sara Kashisaz Zahra Basiri Paknafs Ahmad RiahiIn this paper, an innovated method is used for cooling Milling zone of Stainless Steel via Adaptive Neuro-Fuzzy Inference System (ANFIS) using non-touch laser thermometer for non-touch measuring of the temperature. This method is economically appropriate because of its أکثرIn this paper, an innovated method is used for cooling Milling zone of Stainless Steel via Adaptive Neuro-Fuzzy Inference System (ANFIS) using non-touch laser thermometer for non-touch measuring of the temperature. This method is economically appropriate because of its optimization in using coolant. In comparison to the ways which were designed to optimize the ratio of coolant, this method is the best due to its intelligent, fast and trained system via ANFIS .In this method, not only the designing of the ANFIS and using the non-touch laser thermometer makes the cooling process fast but also the accuracy of the system is improved in comparison to the previous designs according to the results in different statistics criteria including MSE, NMSE, R2 and MAPE, which were calculated. تفاصيل المقالة -
حرية الوصول المقاله
36 - Feasibility Investigation of Hydroforming of Dental Drill Body by FEM Simulation
Mohammad Sajjad Mahdieh Mohammad Reza EstekiApplying numerical methods in the analysis of forming processes, results in the prediction of the process parameters without performing costly and time-consuming laboratory test procedures. The purpose of this study is to evaluate the feasibility of manufacturing a dent أکثرApplying numerical methods in the analysis of forming processes, results in the prediction of the process parameters without performing costly and time-consuming laboratory test procedures. The purpose of this study is to evaluate the feasibility of manufacturing a dental drill body using a hydroforming process. Due to the hygienic issues, the selected material for this part is stainless steel grade 304. The main reason for applying stainless steel in the main body is its hygienic characteristics such as antibacterial surface and washability which makes it appropriate for use in many medical instruments. The hydroforming process is simulated in ABAQUS software and the required parameters of the initial material are obtained from engineering tables. The thickness of the initial part is 0.5 mm and after simulation, it is decreased to 0.38mm. The maximum Von Misses stress of the part reached in this simulation is 708 MPa and the maximum strain rate is 1.233 mm/mm. تفاصيل المقالة -
حرية الوصول المقاله
37 - Study the Percentage of Carbon and Ferrite in Layers of Steel (SA-516) by Strip Cladding with E316L
Ahmad Afsari Dara Fazel Jafar Karimisharifabadi Vahid MehrabiOne of the most important methods to reduce metal corrosion and improve erosion resistance is to use strip cladding with electro slag welding. Applying the strip electrode (E316l), cladding performed on the layer of steel (5A-516) with this process. With changes in the أکثرOne of the most important methods to reduce metal corrosion and improve erosion resistance is to use strip cladding with electro slag welding. Applying the strip electrode (E316l), cladding performed on the layer of steel (5A-516) with this process. With changes in the thickness of cladding layers and the number of these layers, the percentages of ferrite and carbon in samples obtained by WRC equipment were analyzed. The optical microscopy is used to investigate the microstructure of different cladding layers in this research work. Hence, with the increase in the percentage of carbon, the sensitivity of stainless steel to grain boundary corrosion increases. With the reduction of ferrite percentage, the sensitivity to hot cracking increased too, so the overall results indicate that with an increase in the thickness of the first cladding layer, the amount of carbon in this layer increases, this phenomenon reduces the percentage of ferrite in it. Hence, by increasing the number of cladding layers, the amount of carbon percentage reduces considerably while the ferrite percentage reaches the desired amount. تفاصيل المقالة -
حرية الوصول المقاله
38 - Analytical, Experimental and Finite Element Investigation of Internal Pressure Effect in Hydroforming Process on Metallic Bellows Produced from Thin Wall Tube of Austenitic Stainless Steel Grade 316L
Mehdi Arabbeigi Mehran Moradi Boozarjomehr Ghasemi Majid SattarOne of the bellows producing method is hydroforming process .Whereas some factor of hydroforming process specially internal pressure affects on final characteristics produced bellows such as bursting, wrinkling and wall thickness distribution. In this paper the effect o أکثرOne of the bellows producing method is hydroforming process .Whereas some factor of hydroforming process specially internal pressure affects on final characteristics produced bellows such as bursting, wrinkling and wall thickness distribution. In this paper the effect of internal pressure factor in final quality of produced bellows will be investigated. In simulation of process, ABAQUS/Explicit version 6.9 code was used, and also experimental examinations for investigation the effect of this factor has done. The results obtained from methods of analytical, finite element and experimental in this paper has good agreement with each other. Also, the conclusions of this research for prediction of suitable forming pressure could be used as a basis of designing a new type of metal bellows. تفاصيل المقالة -
حرية الوصول المقاله
39 - Micro Machining of AISI 440C Stainless Steel using Magnetic Field and Magnetic Abrasive Particles
Yahya Choopani Mohammad Reza RazfarMagnetic abrasive finishing (MAF) is a micromachining process that uses magnetic field and magnetic abrasive particles to conduct the mechanism of material removal in micro-nanometer scales. In this paper, by an experimental method and statistical analysis, the effects أکثرMagnetic abrasive finishing (MAF) is a micromachining process that uses magnetic field and magnetic abrasive particles to conduct the mechanism of material removal in micro-nanometer scales. In this paper, by an experimental method and statistical analysis, the effects of parameters like working gap, work-piece rotational speed and material removal mechanism (injection of abrasive slurry of Al2O3) in the MAF process, on the external surfaces of cylindrical pieces of stainless steel (AISI 440C)were investigated on surface roughness. To do the experiments, a mechanism was designed and constructed. The results of this research show that the working gap and work-piece rotational speedhave a significant effect on the improvement of the surface roughness. It has been indicated that in vitro surface roughness improved 20% as a result of the gap working of 2 mm, workpiece rotational speed of 355 rpm, using the injection of abrasive slurry of Al2O3. تفاصيل المقالة -
حرية الوصول المقاله
40 - Machinability Improvement of 17-4PH Stainless Steel by Cryogenic Cooling
Salman Khani Mohammad Razfar Masoud Farahnakyan17-4PH stainless steel is a martensitic precipitation hardening stainless steel that provides an outstanding combination of high strength, good corrosion resistance, good mechanical properties, good toughness in both base metal and welds, and short time, low-temperature أکثر17-4PH stainless steel is a martensitic precipitation hardening stainless steel that provides an outstanding combination of high strength, good corrosion resistance, good mechanical properties, good toughness in both base metal and welds, and short time, low-temperature heat treatments that minimize warpage and scaling. This valuable alloy is widely used in the aerospace, nuclear, chemical, petrochemical, food processing, power generation, and naval industries; however, 17-4PH stainless steel is categorized as hard to machine materials due to low thermal conductivity and high toughness. Tool wear in traditional machining of 17-4PH stainless steel is high; hence, low tool life causes high tooling cost. In this paper, indirect cryogenic machining was used, in order to improve machinability of 17-4PH stainless steel in turning operation with TiN coated carbide insert tool. Pressurized-liquid-nitrogen (LN) was used as a cryogenic coolant. Nitrogen gas applied on the liquid nitrogen to pressurize it. A specific tool holder was designed and manufactured for cryogenic turning. Cryogenic machining decreases temperature-dependent tool wear and increases tool life by keeping tool temperature low. Cutting force, tool flank wear and maximum tool temperature have been studied as machinability parameters. Cutting force was measured by the Kistler 9121 piezoelectric dynamometer. The Dino-Lite digital microscope with 20-200X magnification was used to measure tool flank wear. The experimental results showed that cryogenically enhanced machining decreases cutting force and tool flank wear by 22 and 23 percent, respectively, compared with dry turning. Predicting of tool life using linear extrapolation showed that tool life in cryogenic turning improved by 39% over dry turning. In addition, cutting force in cryogenic machining became more stable than the force in dry condition. Thermal analysis of the carbide tool performed in the ANSYS Software using experimental data. Thermal analysis showed that the maximum temperature of cutting tool in cryogenic machining is 75 percent lower than dry condition. تفاصيل المقالة -
حرية الوصول المقاله
41 - None-platinum electrode catalysts and membranes for highly efficient and inexpensive H2 production in microbial electrolysis cells (MECs): A review
Abudukeremu Kadier Washington Logroño Pankaj Kumar Rai Mohd Sahaid Kalil Azah Mohamed Hassimi Abu Hasan Aidil Abdul HamidMicrobial electrolysis cell (MEC) is a gripping bio-electrochemical device producing H2 gas from renewable biomass while at the same time treat wastewater. Through extensive global research efforts in the latest decade, the performance of MECs, including energy efficien أکثرMicrobial electrolysis cell (MEC) is a gripping bio-electrochemical device producing H2 gas from renewable biomass while at the same time treat wastewater. Through extensive global research efforts in the latest decade, the performance of MECs, including energy efficiency, hydrogen production rate (HPR), and hydrogen recovery have achieved significant breakthroughs. However, employing a low-cost, stable and high efficient cathode to replace platinum catalyzed cathode (Pt/C) is the greatest challenge for large-scale industrialization of MEC. Numerous studies have demonstrated that the performance of MEC directly depends on the kinetics of the anode and cathode reactions within the electrolysis cell, with the performance of the electrode catalyst highly affected by the materials they are made from. In a relatively short space of time, a wide range of electrode materials have been tested to amplify the performance of MECs, such as carbon-based electrode catalysts have emerged as promising electrode materials for both anode and cathode construction. Composite materials have also shown to have the potential to become materials of choice for electro-catalyst manufacture. More recently, various transition metal oxides and alloys have been extensively examined as alternatives to conventional expensive noble-metals like platinum for hydrogen evaluation reaction (HER) in MECs. Numerous studies have confirmed that stainless steel, Ni alloys, and Pd nanoparticle decorated cathode are worth mentioning and have very good efficiency. In the present article, we present a comprehensive review centered on the development of a low-cost and high efficient electrode materials and membrane to boost the performance of MECs, including anode, cathode, and membrane. تفاصيل المقالة -
حرية الوصول المقاله
42 - Using Gray Relational Analysis and Taguchi Technique in Solving Multi-objective Problems for Turning Operation of Austenitic Stainless Steel
م. آزادی مقدم ف. کلاهان م. حسینی دوغ آبادیIn this study, the application of gray relational analysis (GRA) and Taguchi method in multi-criteria process parameters selection of turning operation has been investigated. The process responses under study are material removal rate (MRR) and surface roughness (SR); i أکثرIn this study, the application of gray relational analysis (GRA) and Taguchi method in multi-criteria process parameters selection of turning operation has been investigated. The process responses under study are material removal rate (MRR) and surface roughness (SR); in turn, the input parameters include cutting speed, feed rate, depth of cut and nose radius of the cutting tool. The proposed approach employs GRA to convert the values of process outputs, obtained from Taguchi method, into a single objective used to determine the best set of process parameters for turning operation of AISI 202 austenitic stainless steel. Analytical results reveal that the combination of higher levels of cutting speed, depth of cut, and nose radius and lower level of feed rate is essential to achieve simultaneous maximization of material removal rate and minimization of surface roughness. Using verification test, these settings would result in more than 14% improvement over those for initial settings. The analysis of variance (ANOVA) and F-tests showed that nose radius is the major factor affecting the gray relational grade (GRG) with 41% contribution. In general, the proposed procedure is quite efficient in determining the effects of process parameters and finding the best set of process parameters. تفاصيل المقالة -
حرية الوصول المقاله
43 - مطالعه تأثیر حساسشدن بر رفتارخوردگی فولاد زنگنزن دوپلکس SAF 2205 در ناحیه ترانسپسیو
خشایار مرشدبهبهانی پوریا نجفی سیار محمود پاکشیردر این پژوهش، رفتار خوردگی بین دانهای فولاد زنگنزن دوپلکس SAF 2205 در محلول "2 مولار اسید سولفوریک + 1 مولار اسید کلریدریک" در دمای oC 30 با استفاده از آزمونهای پلاریزاسیون پتانسیودینامیک، راکتیواسیون پتانسیوکینتیک الکتروشیمیایی دو حلقهای (DLEPR)، تفرق اشعهایکس و ط أکثردر این پژوهش، رفتار خوردگی بین دانهای فولاد زنگنزن دوپلکس SAF 2205 در محلول "2 مولار اسید سولفوریک + 1 مولار اسید کلریدریک" در دمای oC 30 با استفاده از آزمونهای پلاریزاسیون پتانسیودینامیک، راکتیواسیون پتانسیوکینتیک الکتروشیمیایی دو حلقهای (DLEPR)، تفرق اشعهایکس و طیفسنجی امپدانس الکتروشیمیایی (EIS) مورد بررسی قرار گرفت. طیفسنجی امپدانس الکتروشیمیایی، برای نمونههایی با درجات مختلفی از حساس شدن به مدت 1 و 5 ساعت در دمای oC 725، وجود سه رفتار متفاوت را در پتانسیل های مختلف ناحیه ترانس پسیو نشان داد. نتایج بررسی حاکی از کاهش مقاومت انتقال بار (Rct) و مقاومت پلاریزاسیون (RP) در اثر افزایش زمان حساسشدن میباشد و این نتایج با تصاویر میکروسکوپ نوری و الکترونی از سطح نمونههای خوردهشده همخوانی دارد. تفاصيل المقالة -
حرية الوصول المقاله
44 - بررسی عملیات تمپر بر خواص مکانیکی فولاد زنگ نزن سوپر مارتنزیتی13%Cr
سعید جبارزارع ایمان خیراللهی حسین آبادی سید مسعود صهری رسول قاسمی محمد کویتی ابراهیم شکرانهبه منظور بررسی تأثیر عملیات تمپر بر تغییرات ریزساختاری وخواص مکانیکی فولاد زنگ نزن سوپر مارتنزیتی13%Cr، نمونهها در محدوده دمایی℃720-520و محدوده زمانی 10-3 ساعت تمپر، سپس سرد شدن در هوا انجام گرفته است. پس از عملیات حرارتی، ارزیابی خواص مکانیکی بوسیله آزمون های کشش و سخ أکثربه منظور بررسی تأثیر عملیات تمپر بر تغییرات ریزساختاری وخواص مکانیکی فولاد زنگ نزن سوپر مارتنزیتی13%Cr، نمونهها در محدوده دمایی℃720-520و محدوده زمانی 10-3 ساعت تمپر، سپس سرد شدن در هوا انجام گرفته است. پس از عملیات حرارتی، ارزیابی خواص مکانیکی بوسیله آزمون های کشش و سختی وبررسی ریزساختار به روش میکروسکوپ نوری و میکروسکوپ الکترونی روبشی و همچنین ارزیابی میزان آستنیت باقیمانده، توسط پراش اشعهXبرروی نمونهها انجام گرفت. نتایج نشان داد خواص مکانیکی مطلوب با عملیات آستنیته در℃1050 به مدت 1 ساعت، کوئنچ در آب و عملیات تمپر در ℃600به مدت 3 ساعت و سرد شدن در هوا بدست میآید. تفاصيل المقالة -
حرية الوصول المقاله
45 - بررسی ریز ساختار و خواص مکانیکی اتصال غیر مشابه فولاد زنگ نزن AISI304L به فولاد ASTMA514 به روش جوشکاری قوس تنگستن تحت گاز محافظ
موسی توکلی عباس سعادت محمدرضا خانزاده قره شیرانچکیده در این پژوهش، ریز ساختار و خواص مکانیکی جوشهای غیر مشابه فولاد زنگ نزن آستنیتی AISI 304L به فولاد ASTM A514 مورد بررسی گرفته است. بدین منظور، روش جوشکاری قوس تنگستن-گاز با استفاده از دو نوع فلز پرکننده ER309L و ERNiCr-3 استفاده شده است. پس از جوشکاری، ریز ساختار أکثرچکیده در این پژوهش، ریز ساختار و خواص مکانیکی جوشهای غیر مشابه فولاد زنگ نزن آستنیتی AISI 304L به فولاد ASTM A514 مورد بررسی گرفته است. بدین منظور، روش جوشکاری قوس تنگستن-گاز با استفاده از دو نوع فلز پرکننده ER309L و ERNiCr-3 استفاده شده است. پس از جوشکاری، ریز ساختار مناطق مختلف هر اتصال شامل فلزات جوش، مناطق متأثر از حرارت، فصل مشترکها و مناطق مخلوط نشده مورد ارزیابی قرار گرفته شده است. فلز جوش ERNiCr-3 ریز ساختار کاملاً آستنیتی ایجاد نموده و ریز ساختار فلز جوش ER309L به صورت فریت اولیه همراه با مقداری آستنیت در پایان انجماد بوده است. همچنین، خواص مکانیکی شامل استحکام خمشی، کششی، مقاومت در برابر ضربه، سختی نمونهها بررسی شده است. در آزمایش کشش تمامی نمونهها از منطقه متأثر از حرارت فلز پایه فولاد زنگ نزن آستنیتی 304L و به صورت نرم دچار شکست شده است. میزان استحکام کششی اتصال ایجاد شده با فلز پرکننده ERNiCr-3، MPa593 و با فلز پرکننده ER309L، MPa556 شده است. میزان انرژی جذب شده در اتصال ایجاد شده، فلز پرکننده ERNiCr-3 به طور میانگین 117 ژول و با فلز پرکننده ER309L، 95 ژول شده است. فلز جوش ERNiCr-3 بیشترین سختی، 156 ویکرز را دارا بوده، در حالی که فلز جوش فولاد زنگ نزن آستنیتی ER309L، 127 ویکرز کمترین مقدار را دارا بود. میتوان نتیجه گرفت برای اتصال بین فلز پایه فولاد زنگ نزن آستنیتی AISI304L به فولاد کوئنچ و تمپر شده ASTMA514، ماده پرکنندهی ERNiCr-3 ویژگیهای بهتری از لحاظ خواص مکانیکی ارائه داده است. تفاصيل المقالة -
حرية الوصول المقاله
46 - ارزیابی ریزساختار و خواص مکانیکی اتصال غیر مشابه اینکلوی 825 به فولاد زنگ نزن آستنیتی 316L
مهدی باباجانی مرتضی شمعانیان مسعود کثیریدر این پژوهش اتصال جوشکاری سوپر آلیاژ اینکلوی 825 به فولاد زنگ نزن آستنیتی 316L به روش جوشکاری قوسی تنگستن-گاز با دو فلز پرکننده 625 (ERNiCrMo3) و فولاد زنگ نزن آستنیتی ER308L بررسی گردید. بررسیها نشان دهنده ساختار دندریتی در فلز جوش اینکونل 625 و سلولی-دندریتی در ساخت أکثردر این پژوهش اتصال جوشکاری سوپر آلیاژ اینکلوی 825 به فولاد زنگ نزن آستنیتی 316L به روش جوشکاری قوسی تنگستن-گاز با دو فلز پرکننده 625 (ERNiCrMo3) و فولاد زنگ نزن آستنیتی ER308L بررسی گردید. بررسیها نشان دهنده ساختار دندریتی در فلز جوش اینکونل 625 و سلولی-دندریتی در ساختار فلز جوش 308L بود و هیچ گونه ترک انجمادی در ساختارها مشاهده نشد. در فصل مشترک فلزهای جوش با فلز پایه به جز فصل مشترک فلز پایه L316 با فلز جوش 308L درشت شدن دانه ها مشاهده شد. از نظر خواص مکانیکی فلز جوش جوشکاری شده با سیم جوش اینکونل 625 با استحکام نهایی 562/5 مگاپاسکال، دارای خواص مکانیکی بهتری بود. تفاصيل المقالة -
حرية الوصول المقاله
47 - مطالعه تجربی و نظری اثر بازدارندگی مایع یونی ایمیدازولیومی بر خوردگی فولاد زنگ نزن- 316 با استفاده از آزمونهای الکتروشیمیایی و نظریه های کوانتومی
رضا صفری علی احسانی حمیدرضا ابراهیمیدر این پژوهش، اثر بازدارندگی ترکیب مایع یونی- ایمیدازولی در خوردگی فولاد زنگ نزن 316 (درمحلول اسیدی HCl) به کمک آزمونهای الکتروشیمیایی، مانند منحنی های پلاریزاسیون و اسپکتروسکوپی امپدانس الکتروشیمیایی، مورد بررسی قرار گرفت. همچنین، بررسی ها نشان داد که جذب این بازدارند أکثردر این پژوهش، اثر بازدارندگی ترکیب مایع یونی- ایمیدازولی در خوردگی فولاد زنگ نزن 316 (درمحلول اسیدی HCl) به کمک آزمونهای الکتروشیمیایی، مانند منحنی های پلاریزاسیون و اسپکتروسکوپی امپدانس الکتروشیمیایی، مورد بررسی قرار گرفت. همچنین، بررسی ها نشان داد که جذب این بازدارنده بر سطح فولاد از مدل همدمای لانگمویر پیروی نمود و مقدار انرژی آزاد گیبس جذب سطحی این بازدارنده برابر 57/8-کیلو ژول بر مول است. سپس، با استفاده از نظریه تابعیت چگالی (DFT) و نظریه کوانتومی اتم-در-مولکول، AIM، جهت مطالعه ساختار آلی-الکترونی و سازوکار انتقال محلی بار و انرژی در یک سامانه مولکولی ایمیدازولی در مقیاس اتمی استفاده شد. در این راستا، خواص الکترونی بسترهای اتمی (مانند چگالی الکترونی و لاپلاسی آن) و همچنین گاف میان اربیتالهای مرزی (HLG) این سامانه آلی-مولکولی بررسی و محاسبه شد. نتایج به دست آمده نشان داد که این مایع یونی پیشنهادی می تواند به عنوان یک مهارکننده سبز مورد استفاده قرار گیرد که از لحاظ اقتصادی سنتز آزمایشگاهی آن نیز مقرون به صرفه هست. مطالعات کوانتومی نیز نشان داد که اتمهای نیتروژن این بازدارنده نقش بسزایی در توزیع محلی انتقال بار و انرژی درون مولکولی (و به تبع آن چگونگی رخداد سازوکارهای الکتروشیمیایی سامانه) دارند. تفاصيل المقالة -
حرية الوصول المقاله
48 - ارزیابی خواص مکانیکی جوش های غیر مشابه فولاد زنگ نزن AISI 347 به فولاد کم آلیاژ ASTM A335
ایمان حاجیان نیادراین تحقیق، خواص مکانیکی جوش های غیرمشابه فولاد زنگ نزن آستنیتی 347 AISI به فولادکم آلیاژ ASTM A335 با استفاده از روش قوسی تنگستن-گاز با قطبیت منفی مورد بررسی قرار گرفت. بدین منظور از دو فلز پرکننده ERNiCr-3 و ER309L استفاده شد. برای بدست آوردن ساختار مطلوب و خواص مکان أکثردراین تحقیق، خواص مکانیکی جوش های غیرمشابه فولاد زنگ نزن آستنیتی 347 AISI به فولادکم آلیاژ ASTM A335 با استفاده از روش قوسی تنگستن-گاز با قطبیت منفی مورد بررسی قرار گرفت. بدین منظور از دو فلز پرکننده ERNiCr-3 و ER309L استفاده شد. برای بدست آوردن ساختار مطلوب و خواص مکانیکی عالی در اتصالات مذکور، کنترل حرارت ورودی و عملیات حرارتی پیشگرم، از جمله پارامترهای موثر و قابل کنترل بود. ریزساختار فلزات پایه و فلزات جوش، با استفاده از میکروسکوپ نوری مورد ارزیابی قرار گرفت و برای بررسی سطوح شکست، از میکروسکوپ الکترونی روبشی1(SEM) استفاده شد. بررسی های ریزساختاری نشان داد که یک ساختار دو فازی شامل مناطق دندریتی و بین دندریتی در فلز جوش ERNiCr-3 با انجماد به صورت آستنیتی و در فلز جوش ER309L ساختاری شامل فریت اولیه استخوانی شکل در زمینه آستنیت مشاهده شد. همچنین خواص مکانیکی، شامل استحکام خمشی، استحکام کششی، مقاومت در برابر ضربه، سختی و نیز شکست نگاری نمونهها بررسی شد. در آزمایش کشش تمامی نمونهها، از منطقه 2HAZ فلز پایه فولادکم آلیاژ 335A و به صورت نرم دچار شکست شدند. تفاصيل المقالة -
حرية الوصول المقاله
49 - پایش خوردگی مخزن اسید سولفوریک تحت حفاظت آندی به وسیله نویز الکتروشیمیایی
احسان صائب نوری موسی محمدیاندر این تحقیق، مخزن از فولاد ساده کربنی بررسی گردید. مخزن حاوی اسید سولفوریک 98 درصد و72 درصد توسط آزمون پلاریزاسیون، پتانسیل مدار باز و پتانسیواستاتیک مورد ارزیابی قرار گرفت. همچنین نویز الکتروشیمیایی قبل، حین و پس از حفاظت آندی انجام گرفت و نتایج حاصل توسط آنالیز آماری أکثردر این تحقیق، مخزن از فولاد ساده کربنی بررسی گردید. مخزن حاوی اسید سولفوریک 98 درصد و72 درصد توسط آزمون پلاریزاسیون، پتانسیل مدار باز و پتانسیواستاتیک مورد ارزیابی قرار گرفت. همچنین نویز الکتروشیمیایی قبل، حین و پس از حفاظت آندی انجام گرفت و نتایج حاصل توسط آنالیز آماری در دامنههای زمانی بررسی شد. پارامترهایی نظیر مقاومت نویز، مقادیر چولگی، کشیدگی جریان و پتانسیل و ضریب خوردگی موضعی محاسبه شدند. با آنالیز در دامنه فرکانسی، منحنیهای دانسیته طیف توان به دست آورده شد. مشاهده شد که مقادیر چولگی و کشیدگی جریان و پتانسیل میتوانند برای تعیین انحراف و یا عدم انحراف از توزیع نرمال داده های نویز الکتروشیمیایی، به کار برده شوند. همچنین مشخص شد که با استفاده از منحنیهای دانسیته طیفی توان میتوان اثرات منفی نویزهای اضافی را حذف نمود و اطلاعات کاملی در مورد پروسه خوردگی به دست آورد. مقاومت نویز بدست آمد ولیکن مقاومت نویز میتواند برای تعیین شدت خوردگی به طور کیفی به کار رود. در این تحقیق، نتیجه گرفته شد که روش نویز الکتروشیمیایی، روشی کارآمد برای مطالعه پدیده های خوردگی، از قبیل خوردگی حفره ای و بررسی سیستم حفاظت آندی در حین حفاظت از مخازن و مبدل ها در محیط اسید سولفوریک میباشد. مشخص شد که برای مخزن فولاد ساده کربنی در اسید سولفوریک 98% در زمان حفاظت مقدار شیب ناحیه ROLL-OFF برابر با 4/2 و برای اسید سولفوریک رقیق 4/4 اندازه گیری شد و مشخص شد در این ناحیه حفاظت آندی به مراتب برای فولاد کربنی در محلول اسید سولفوریک 72% مناسب تر است. تفاصيل المقالة -
حرية الوصول المقاله
50 - تأثیر علمیاتحرارتی حساسشدن و پرداختسطح بر خواص لایه پسیو فولاد زنگنزن دوپلکس SAF 2205
خشایار مرشدبهبهانی محمود پاکشیر پوریا نجفی سیار نیکا ذاکریندر این پژوهش، خواص لایه پسیو فولاد زنگنزن دوپلکس SAF 2205 در محلول اسید سولفوریک و درجه حساس شدن آنها (پس از 1 و 5 ساعت عملیات حرارتی) با استفاده از آزمون راکتیواسیون پتانسیوکینتیک الکتروشیمیایی دو حلقه (DLEPR) مورد ارزیابی قرار گرفت که همخوانی خوبی با نتایج حاصل از آز أکثردر این پژوهش، خواص لایه پسیو فولاد زنگنزن دوپلکس SAF 2205 در محلول اسید سولفوریک و درجه حساس شدن آنها (پس از 1 و 5 ساعت عملیات حرارتی) با استفاده از آزمون راکتیواسیون پتانسیوکینتیک الکتروشیمیایی دو حلقه (DLEPR) مورد ارزیابی قرار گرفت که همخوانی خوبی با نتایج حاصل از آزمون اچ هیدروکسید سدیم برای طبقهبندی ساختار فولادهای زنگنزن دوپلکس داشت. همچنین، آزمون پلاریزاسیون پتانسیودینامیک به منظور تعیین محدوده پتانسیل پسیو در نمونههای آنیل محلولی و حساسشده صورت پذیرفت. پلاریزاسیون سیکلی اعمالی در شاخه آندی آلیاژ حساسشده با زبری سطح مختلف، سودمندی یکنواختی و کمبودن زبری سطح بر افزایش مقاومت لایه پسیو را نشان داد. به منظور ارزیابی دانسیته عیوب نقطه ای لایه پسیو فولاد زنگنزن، آنالیز موت-شاتکی انجام شد تا غلظت دهندههای الکترون در سطح تعیین گردید. نتایج نشان داد که کاهش زبری سطح، کاهش درجه حساس شدن و افزایش تعداد سیکل های پلارزاسیون باعث کاهش دانسیته عیوب سطحی تا 44 درصد خواهد شد. از همین رو، هر چه درجه حساسشدن و زبری سطح بیشتر باشد، لایه پسیو آلیاژ در اثر تشکیل فاز سیگما و کاهش میکروپیلهای موجود در سطح معیوبتر خواهد بود. تفاصيل المقالة -
حرية الوصول المقاله
51 - بررسی رفتار اکسیداسیون و الکتریکی فولاد AISI 304 پوشش داده شده با کبالت برای کاربرد پیل های سوختی اکسید جامد
محمد رضا عاشور زاده مرتضی زند رحیمی هادی ابراهیمی فرمقاومت به اکسیداسیون و هدایت الکتریکی فولادهای زنگ نزن مورد استفاده به عنوان صفحات اتصال دهنده در پیل های سوختی اکسید جامد را می توان با استفاده از یک لایه پوشش رسانا و محافظ بهبود داد. در این پژوهش فولاد زنگ نزن آستنیتی AISI 304 در یک مخلوط پایه پودری کبالت به روش سمان أکثرمقاومت به اکسیداسیون و هدایت الکتریکی فولادهای زنگ نزن مورد استفاده به عنوان صفحات اتصال دهنده در پیل های سوختی اکسید جامد را می توان با استفاده از یک لایه پوشش رسانا و محافظ بهبود داد. در این پژوهش فولاد زنگ نزن آستنیتی AISI 304 در یک مخلوط پایه پودری کبالت به روش سمانتاسیون فشرده پوشش داده شد. از تست اکسیداسیون همدما برای بررسی مقاومت به اکسیداسیون نمونه های پوشش دار و بدون پوشش استفاده شد. همچنین ASR به عنوان تابعی از زمان اکسیداسیون همدما در دمای ºC800 اندازه گیری شد. میکروساختار لایه پوشش و نمونه های اکسید شده توسط میکروسکوپ الکترونی SEM و دستگاه پراش پرتو ایکس بررسی شد. نتایج نشان داد که نمونه های پوشش داده شده با کبالت مقاومت به اکسیداسیون بهتری نسبت به نمونه های بدون پوشش از خود نشان دادند. نتایج نشان داد که افزایش زمان موجب افزایش ASR می شود. همچنین لایه پوشش کبالت در طول فرآیند اکسیداسیون همدما تبدیل به اسپینل های CoFe2O4، Co3O4 وCoCr2O4 شد. اسپینل های کبالت مقدار ASR ( mΩ cm24/27) کمتری را در مقایسه با نمونه بدون پوشش ( mΩ cm25/60) از خود نشان دادند. تفاصيل المقالة -
حرية الوصول المقاله
52 - تأثیر عملیات حرارتی بر ریزساختار، خواص مکانیکی و رفتار خوردگی قطعات فولاد زنگ نزن دو فازی 2209 تولید شده توسط روش تولید افزودنی مبتنی بر سیم و قوس الکتریک
علی ملازاده کشکوئی محمود شریفی تبار مهدی شفیعی آفارانیدر این پژوهش به ساخت دیواره فولاد زنگ نزن دوفازی توسط فرآیند تولید افزودنی مبتنی بر سیم و قوس و بررسی ساختار، ریزساختار، خواص مکانیکی و خوردگی آن پرداخته شده است. نتایج آنالیز پراش اشعه ایکس وجود فازهای فریت و آستنیت در ساختار را نشان داد. بررسی های ریزساختاری نشان دهند أکثردر این پژوهش به ساخت دیواره فولاد زنگ نزن دوفازی توسط فرآیند تولید افزودنی مبتنی بر سیم و قوس و بررسی ساختار، ریزساختار، خواص مکانیکی و خوردگی آن پرداخته شده است. نتایج آنالیز پراش اشعه ایکس وجود فازهای فریت و آستنیت در ساختار را نشان داد. بررسی های ریزساختاری نشان دهنده توزیع غیریکنواخت فازهای فریت و آستنیت در ریزساختار نمونه پس از تولید بود. جهت بررسی خواص مکانیکی دیواره از آزمون کشش و آزمون میکروسختی در مناطق مختلف دیواره استفاده شد. بر اساس نتایج این آزمون ها، مقدار میانگین استحکام تسلیم و استحکام کششی در راستای جوشکاری به ترتیب در حدود 7/2 و 5/5 درصد بیشتر و مقدار قابلیت تغییر طول در حدود 5/4 درصد کمتر از راستای رسوب گذاری بود. عملیات حرارتی پس از تولید در دمای 1000 درجه سلسیوس به مدت 30 دقیقه موجب ریز شدن دانههای فریت و آستنیت، هم محور شدن ساختار، افزایش درصد آستنیت و بهبود میزان سختی ویکرز از مقدار میانگین 318 به 376 شد. سطح شکست تمامی نمونهها حاکی از مکانیزم شکست نرم بود. نتایج آزمون خوردگی نشان داد که عملیات حرارتی موجب افزایش مقاومت به خوردگی فولاد شد. تفاصيل المقالة -
حرية الوصول المقاله
53 - بررسی رفتار خوردگی بین دانهای فولاد زنگ نزن مارتنزیتی UNS S42000 با استفاده از طیفسنجی امپدانس الکتروشیمیایی پتانسیودینامیک
خشایار مرشدبهبهانی پوریا نجفی سیار محمود پاکشیر نیکا ذاکریندر این پژوهش، عملیات حرارتی تمپر در دمای ثابت 550 درجه سانتیگراد و زمانهای متفاوتی از 5/0 تا 24 ساعت بر روی نمونههای فولاد زنگنزن مارتنزیتی UNS S42000 صورت گرفت تا بتوان رفتار خوردگی بیندانهای آلیاژ را مورد بررسی قرار داد. خصوصیات میکروساختار و خواص الکتروشیمیایی أکثردر این پژوهش، عملیات حرارتی تمپر در دمای ثابت 550 درجه سانتیگراد و زمانهای متفاوتی از 5/0 تا 24 ساعت بر روی نمونههای فولاد زنگنزن مارتنزیتی UNS S42000 صورت گرفت تا بتوان رفتار خوردگی بیندانهای آلیاژ را مورد بررسی قرار داد. خصوصیات میکروساختار و خواص الکتروشیمیایی آلیاژ به ترتیب با استفاده از میکروسکوپ الکترونی روبشی و روش پلاریزاسیون آندی ارزیابی شدند. خوردگی موضعی نمونهها نیز با استفاده از روش طیفسنجی امپدانس الکتروشیمیایی پتانسیودینامیک در ناحیه پتانسیل ترانسپسیو صورت گرفت. نتایج حاکی از خوردگی بیندانهای شدیدی برای نمونههایی با 2 ساعت عملیات حرارتی تمپر بود، درصورتیکه زمانهای طولانی عملیات حرارتی تمپر به دلیل حساسیتزدایی موجب تقلیل اثر تمپر بر خوردگی بیندانهای میشود. علاوه بر این، نتایج طیفسنجی امپدانس الکتروشیمیایی پتانسیودینامیک نشان داد که مقاومت انتقال بار نمونهها در پتانسیل 10/1 ولت میتواند بهعنوان معیار مهمی بهمنظور بررسی خوردگی بیندانهای فولادهای زنگ نزن مارتنزیتی مورد استفاده قرار گیرد، بدینصورت که هرچه مقاومت انتقال بار در این پتانسیل کمتر باشد، مقاومت به خوردگی بیندانهای نیز کمتر خواهد بود. این نتایج در تطابق با تصاویر مربوط به مورفولوژی سطوح خورده شده بوده که بیانگر خوردگی یکنواخت، خوردگی موضعی و حساسیتزدایی به ترتیب برای نمونههای تمپر نشده، زمانهای کوتاه تمپر و زمانهای طولانی تمپر میباشد. تفاصيل المقالة -
حرية الوصول المقاله
54 - Effect of heat treatment on microstructural properties of three-layer sheet aluminum magnesium - aluminum - stainless steel
داوود میراحمدی ابوالفضل غلام زادهMetal coating, metal materials are of two or more layers. The coating metals are widely used in industry. These sheets or saving performance and cost effective solution or both the user. Performance coating metals according to usage in structural applications, settings أکثرMetal coating, metal materials are of two or more layers. The coating metals are widely used in industry. These sheets or saving performance and cost effective solution or both the user. Performance coating metals according to usage in structural applications, settings thermal expansion of the thermo-mechanical control (thermostat), electrical, magnetic, corrosion resistant, flowering and decorative connection is divided. In each action, you may have attended several coating metal system.In this study, using the process connectors, three-layer aluminum sheet net aluminum, stainless steel was producedd Magnesium-. Examples of cross-links in different situations rolled and annealed photos were taken. In order to determine the best conditions for the production of multi-layer sheet, the effect of process parameters were evaluated connectors. Changes in different mechanical properties by tensile test was performed according to ASTM E8M allowed. The survey showed that the samples annealed at temperatures above 375 ° C for aluminum, a substantial increase bond strength of the samples has been rolled. تفاصيل المقالة -
حرية الوصول المقاله
55 - Optimization of the Pulsed Gas Tungsten Arc Welding in Dissimilar Joining Austenitic Stainless Steel AISI 316L to Nickel-Base Super Alloy of Monel 400
علی خلیلی مسعود کثیری عسگرانی مرتضی شمعانیانIn this research, optimization of the pulsed gas tungsten arc welding including pulse current, background current, pulse frequency and on time were investigated in welding of non-similar materials of austenitic stainless steel AISI 316L and nickel-base super alloy of Mo أکثرIn this research, optimization of the pulsed gas tungsten arc welding including pulse current, background current, pulse frequency and on time were investigated in welding of non-similar materials of austenitic stainless steel AISI 316L and nickel-base super alloy of Monel 400 by using ERNiCr3 filler metal. In order to obtain optimum conditions of welding the Taguchi method with the L9 array was used. The mechanical properties such as bending, tesile test and hardness test were performed on the samples and after that analysis of the variance was performed. By predicting optimal conditions, the proposed model was examined and the results of computational analysis shows a significant similarity with results of the experiment. Optimal parameters of pulsed tungsten arc welding were the pulse current of 140 mA, background current of 60 mA, pulse frequency of 3 Hz and the ON periods of pulse was 50%. The optimized sample with the Taguchi method and the welded sample shows the similarity of 98.7%. Pulse current percentage of 23.4 and pulse frequency of 28.2 were identified as the most influential parameters during the welding. Tensile test results showed that the failure occurs on the side of the base metal on Monel 400 one and hence the failure is the ductile one. These results show the strength of the weld metal confirmed the tensile and bending tests تفاصيل المقالة -
حرية الوصول المقاله
56 - Investigating on process variables effect of AISI 304 stainless steel machining using minimum quantity lubricant on cutting force
Mohammad Ali Safataj Sayed Ehsan Mirmohammadsadeghi Reza AbedinzadehIn the machining process, the friction between the tool and the surface being machined, in addition to the destructive effects on tool wear and surface quality, increases the cutting force. By applying lubricant, it is possible to reduce the friction force in the machin أکثرIn the machining process, the friction between the tool and the surface being machined, in addition to the destructive effects on tool wear and surface quality, increases the cutting force. By applying lubricant, it is possible to reduce the friction force in the machining process, and as a result, the cutting force is reduced. Due to the harmful environmental effects of excessive use of lubricants, the method of minimum quantity lubricant (MQL) can be helpful. In this method, fluid is applied with controlled flow and pressure. In this research, the effect of machining conditions on the cutting force for the machining process of AISI 304 stainless steel, using the method of minimum quantity lubricant has been investigated. The results show that with the increase in the cutting speed, the cutting force has decreased. Also, with the increase of injection pressure when applying the lubricating fluid using the method of the minimum quantity lubricant, a significant increase in the cutting force has been observed. تفاصيل المقالة
سند
Sanad is a platform for managing Azad University publications
الروابط
المراكز ذات الصلة
دعامة
الصفحات الرسمية
حقوق هذا الموقع الإلكتروني مملوكة لنظام SANAD Press Management. © 1442-1445