• فهرس المقالات Ti-6Al-4V

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        1 - The Effect of Heat Treatment on the Structure of PEO Coating on Ti-6Al-4V Alloy
        M Garshasbi A Shokuhfar M Ghanbari Haghighi B Karbakhsh
        In order to increase the corrosion resistance and improve the biocompatibility of Ti-6Al-4V alloy used in medical applications such as implants, it has been modified with various methods including PEO. On the other hand, this alloy is also capable of heat treatment. In أکثر
        In order to increase the corrosion resistance and improve the biocompatibility of Ti-6Al-4V alloy used in medical applications such as implants, it has been modified with various methods including PEO. On the other hand, this alloy is also capable of heat treatment. In this study, firstly different structures were obtained by heat treatment of Ti-6Al-4V substrate and then different structures were coated with the same parameters, by PEO method. The scanning electron microscope equipped with EDS was used to investigate the morphology and cross-sectional of ​​the coatings. X-ray diffraction was also applied to analyze the phases created in the coating. Additionally, investigation of surface topography was performed by atomic force microscopy. Results have represented that the martensitic structure has a lower porosity with more regular dispersion. The creation of coating with martensitic structure also shows good thickness with high quality smoothness. On the other hand, the coating of the α-plate and inter-grain β structure were included large and irregular porosities. تفاصيل المقالة
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        2 - Joining of Ti-6AL-4V to AISI 304 Stainless Steel using Laser Spot Welding with Circular Technique
        M Rafi H Sabet V Abouei Mehrizi A Anbarzadeh
        In this research, dissimilar laser spot welding of the Ti-6Al-4V and AISI 304 (stainless steel) was investigated. The joining of 0.7 and 0.5 mm thickness plates with using a copper interlayer of 0.2 and 0.3 mm in thickness was performed by LSW. A 400-W Nd: YAG laser pul أکثر
        In this research, dissimilar laser spot welding of the Ti-6Al-4V and AISI 304 (stainless steel) was investigated. The joining of 0.7 and 0.5 mm thickness plates with using a copper interlayer of 0.2 and 0.3 mm in thickness was performed by LSW. A 400-W Nd: YAG laser pulse welding machine was used to obtain coaxial spot welds of 4 mm in diameter with circular technique. Visual inspection and metallographic examination were used for all samples. If no crack was identified, micro-Vickers hardness test, tensile test, and scanning electron microscopy (SEM) were performed on the samples. The result indicated that with a copper interlayer and 10.7 J heat input on peak power of 1.5 kW, welding frequency 15 Hz, and welding time of 7 ms, leading to an ultimate strength of 160 MPa. In addition the result indicated that applying the circular technique by creating adjacent spot welds can produce a good joint. تفاصيل المقالة
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        3 - Preform and Process Design of Ti-6Al-4V Compressor Blade using Equipotential Lines and 3D FE Simulation
        M. Soleimanzadeh M.M. Fallah
        Forging is one of the most important processes for production of titanium parts. Selection and evolution of forging parameters such as the forging preforms, part and die temperatures and strain rate are of great importance to achieve optimal process. In this work, a com أکثر
        Forging is one of the most important processes for production of titanium parts. Selection and evolution of forging parameters such as the forging preforms, part and die temperatures and strain rate are of great importance to achieve optimal process. In this work, a comprehensive study on the near net hot forging of a Ti-6Al-4V compressor blade is performed through designing several preforms and simulating the process in several die and preform temperatures. The Equipotential lines method is used for the optimal design of preforms and Johnson-Cook constitutive model is used for 3D FE simulations and the criteria for selecting the parameters was the material temperature during the process that is necessary for achieving desired properties of Ti-6Al-4V parts. According to the results, performing the isothermal forging process in increased speeds could lead to increasing the temperature over the β-transus and improper mechanical properties development. So, finding a proper die and preform temperature is necessarily accomplished in this work. According to results the appropriate temperatures for performing the process using modified 0.1v preform and ram speed of 1mm/s were 1050˚C and 450˚C for the preform and die respectively. تفاصيل المقالة
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        4 - Application of the Relevance Vector Machine for Modeling Surface Roughness in WEDM Process for Ti-6Al-4V Titanium Alloy
        Abolfazl Foorginejad Nader Mollayi Morteza Taheri
        Cutting the Titanium alloys is a complicated task which cannot be performed by traditional methods and modern machining processes, such as Wire electro-discharge machining (WEDM) process which are mainly used for this purpose. As a result of the high price of the Ti-6Al أکثر
        Cutting the Titanium alloys is a complicated task which cannot be performed by traditional methods and modern machining processes, such as Wire electro-discharge machining (WEDM) process which are mainly used for this purpose. As a result of the high price of the Ti-6Al-4V alloy, proper tuning of the input parameters so as to attain a desired value of the surface roughness is an important issue in this process. For this purpose, it is necessary to develop a predictive model of surface roughness based on the input process parameters. In this paper, The Taguchi method was used for the design of the experiment. According to their effectiveness, the input parameters are pulse-on time, pulse-off time, wire speed, current intensity, and voltage; and the output parameter is surface roughness. However, a predictive model cannot be defined by a simple mathematical expression as a result of the complicated and coupled multivariable effect of the process parameters on the surface roughness in this process. In this study, application of the relevance vector machine as a powerful machine learning algorithm for modeling and prediction of surface roughness in wire electro-discharge machining for Ti-6Al-4V titanium alloy has been investigated. The predicting result of model based on the root means square error (RMSE) and the coefficient of determination (R2) statistical indices, prove that this approach provides reasonable accuracy in this application. تفاصيل المقالة
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        5 - Microstructure Investigation and Mechanical Properties of Resistance Upset Butt Welded Ti-6Al-4V Alloy
        Mahmood Sharifitabar
        In the present study, resistance upset butt welding was used as a solid-state process for joining Ti-6Al-4V alloy. Results showed that melting and subsequent solidification of the alloy at the joint interface promoted the development of a cast microstructure along with أکثر
        In the present study, resistance upset butt welding was used as a solid-state process for joining Ti-6Al-4V alloy. Results showed that melting and subsequent solidification of the alloy at the joint interface promoted the development of a cast microstructure along with some pores. However, by applying the constant upset pressure of 1.62 MPa, the pore volume fraction decreased considerably with decreasing the welding current from 110 A/mm2 to 55 A/mm2. Hardness test results showed that the weld interface and the base material had the highest (352 HV) and the lowest (318 HV) values, respectively. The microstructure of the interface consisted of ά martensite and Widmanstätten laths. The tensile strength of the joints varied between 550 and 883 MPa depending on the welding parameters used. In the optimum condition, the maximum strength of the joint was about 94% of the base metal strength. Fractography of samples confirmed that the formation of pores deteriorated the strength of the joints. تفاصيل المقالة
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        6 - Fatigue and corrosion fatigue properties of Ti-6Al-4V implant grade titanium alloy in Ringer solution
        Mahmoud Hajisafari Arman Zare Bidaki Saeid Yazdani
        Nowadays modification of metallic biomaterials which are used as implants for bone and hard tissues replacement is considered as an important subject. In the current study, corrosion fatigue properties of Ti-6Al-4V alloy investigated via Rotating-Bending standard test m أکثر
        Nowadays modification of metallic biomaterials which are used as implants for bone and hard tissues replacement is considered as an important subject. In the current study, corrosion fatigue properties of Ti-6Al-4V alloy investigated via Rotating-Bending standard test method and then, the results compared with the fatigue properties of the specimens tested in the same conditions. Scanning electron microscopy used to investigate the chemical composition (EDS- Energy-dispersive X-ray spectroscopy), microstructural features and crack propagation characteristics. Results showed that the presence of corrosive environment not only results in decrease in fatigue life, but also eliminates the fatigue limit. Further studies revealed that aggregation of corrosion products, with more hardness values, at the crack tip cause an obvious deviation of crack propagation from its main direction. Therefore, a tortuous crack path through the bulk of the specimens was detected concurrent with penetration of solution into the crack. In addition, dimensions and morphology of fatigue crack surfaces were completely different from corrosion fatigue cracks as well. تفاصيل المقالة
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        7 - Fabrication and characterization of the Ti-6Al-4V/Mg scaffold
        Seyed Kalantari Hossein Arabi Shamsodin Mirdamadi Seyed Mirsalehi
        Ti–6Al–4V scaffolds were fabricated by powder metallurgical space holder technique in this research. The most added magnesium (Mg) powder was evaporated and a skeleton of Ti-6Al-4V alloy was produced. For this purpose Ti-6Al-4V and Mg powders mixture compact أکثر
        Ti–6Al–4V scaffolds were fabricated by powder metallurgical space holder technique in this research. The most added magnesium (Mg) powder was evaporated and a skeleton of Ti-6Al-4V alloy was produced. For this purpose Ti-6Al-4V and Mg powders mixture compacted in a steel die by applying uniaxial pressure of 500 MPa before sintering the green product in a sealed quartz tubes at 900 °C for 2 hours. Employing Archimedes’ principle and an Image Tool software, the total and open volume percent of porosities within the scaffolds were found to be in the range of 46-64% and 41-47%, respectively. Bioactivity properties of the scaffolds were investigated in a simulated body fluid (SBF). Scanning electron microscopy (SEM) and Energy dispersive spectroscopy (EDS) were used for studying the specimens’ surfaces after immersing them for 28 days. The results showed that the amounts of calcium (Ca) and phosphor (P) deposited into the porous areas were more than that of smooth surfaces due to the presence of Mg particles within the pores which provoked formation of apatite layers. Changing in the pH values of the SBF during 18 days of immersion revealed that gradual improvement in pH level due to releasing OHˉ .Using atomic absorption spectroscopy (AAS) indicated that by increasing Mg content of scaffolds, Ca concentration of SBF decreased which is an indication of apatite formation on the scaffold. Results of SBF bioactivity assays exhibited that the scaffold with 60 vol.% Mg has the best ability to induce apatite nucleation. تفاصيل المقالة
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        8 - Simulation of Plastic Deformation Behavior of Ti-6Al-4V Alloy by Finite Element Method
        E Amini F Madadi Sh Katani M Atapoor
        Mechanical properties of alloys have a strong relation with microstructure and determination of their behavior can lead to multiple advantages. To obtain this goal, finite element method )FEM( is one of the best ways. In this study a series of experiments were carried o أکثر
        Mechanical properties of alloys have a strong relation with microstructure and determination of their behavior can lead to multiple advantages. To obtain this goal, finite element method )FEM( is one of the best ways. In this study a series of experiments were carried out on the produced Ti-6Al-4V to obtain its mechanical characteristics and to prepare it for photographing in micro dimensions. Next, using scanning electron microscopy (SEM), images were taken from some regions of the manufactured Ti-6Al-4V. In the next step, a method was developed to separate alpha-phases from beta-phases with a relatively high accuracy. At the end of this stage, the images were mapped into a matrix involving arrays which show the type of the phases. A code is written which maps the material matrices to the FEM model. The Gurson model is an appropriate model for simulating the damage inside the ductile material. Results of simulations obtained from SEM images show that the simulation data are in good agreement with experimental results and also analysis of simulation clearly shows that the failure always happens in boundaries between two different phases; ductile and brittle, and then growth over them to form the final failure of the material. تفاصيل المقالة
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        9 - 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 Dehkordi
        Both 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 أکثر
        Both 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
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        10 - Effect of Coating Process Parameters on Corrosion Behavior of Ti-6Al-4V
        Mohammad Hossein Majidi Amin Rabiezadeh Ahmad Afsari
        Titanium and its alloys (Ti-6Al-4V) are considered to be among the most promising engineering materials due to a unique combination of high strength to weight ratio, melting temperature, corrosion resistance, and biocompatibility. Anodizing is one of the coating methods أکثر
        Titanium and its alloys (Ti-6Al-4V) are considered to be among the most promising engineering materials due to a unique combination of high strength to weight ratio, melting temperature, corrosion resistance, and biocompatibility. Anodizing is one of the coating methods that increases corrosion resistance and wear resistance and provides better adhesion of paint primers mostly applied to protect Al, Ti, Mg, and their alloys. The novel Plasma Electrolytic Oxidation (PEO) technique is gaining increased attention for depositing thick, dense, corrosion resistant, and hard ceramic coating on valuable metals (Al, Ti, and Mg). The aim of this research is a comparison between the corrosion behavior of anodized and plasma electrolytic oxidized Ti-6Al-4V at different voltages. The surface morphology, thickness, and phase composition of coatings were investigated using a scanning electron microscope and X-ray diffraction. The potentiodynamic polarization test was used to determine the corrosion behavior of the specimens. Results indicated that increasing of corrosion resistance by tests anodized sample at 50 V at 15 minutes and PEO sample at 375 V at 10 minutes. تفاصيل المقالة
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        11 - Survey and Study of Machinability for Titanium Alloy Ti-6Al-4V through Chip Formation in Milling Process
        Hassan Gheisari Ebrahim Karamian
        Most of the materials used in the industry of aero-engine components generally consist of titanium alloys. Advanced materials, because of their excellent combination of high specific strength, light weight and general corrosion resistance. In fact, chemical wear resista أکثر
        Most of the materials used in the industry of aero-engine components generally consist of titanium alloys. Advanced materials, because of their excellent combination of high specific strength, light weight and general corrosion resistance. In fact, chemical wear resistance of aero-engine alloy provides a serious challenge for cutting tool material during the machining process. The reduction in cutting temperature distributions leads to an increase in tool life and a decrease in wear rate. Hence, the chip morphology and segmentation play a predominant role in determining machinability and tool wear during the machining process. The result of low thermal conductivity and diffusivity of this alloy is in the concentration of high temperatures at the tool-work-piece and tool-chip interface. Consequently, the chip morphology is very important in the study of machinability of metals as well as the study of cutting tool wear. Otherwise, the result will be accelerating tool wear, increasing manufacturing cost and time consuming. تفاصيل المقالة
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        12 - Simulation of Tool Rotation and Travelling Speed Effects on Friction Stir Welding of Ti-6Al-4V
        Hamed Aghajani Derazkola
        In this research, the effects of parameters include tool rotational and traverse speeds were investigated on heat generation and material flow during friction stir welding of Ti-6Al-4V alloy with computational fluid dynamics (CFD) method. Simulation results showed that أکثر
        In this research, the effects of parameters include tool rotational and traverse speeds were investigated on heat generation and material flow during friction stir welding of Ti-6Al-4V alloy with computational fluid dynamics (CFD) method. Simulation results showed that with increasing of tool rotational and decreasing tool traverse speed, the more frictional heat generates which causes formation of bigger stir zone. Results indicate that the rotation of the shoulder can accelerate the material flow behavior near the top surface. The temperature field in the friction stir welding of Ti-6Al-4V alloy was anti symmetric to the welding line. Due to the results the heat generation and temperature distribution at advancing side were more than retreating side in all joint conditions. According to the results unsmooth and disarray flow patterns were formed in stir zone which caused formation of banded layer structure in advancing side. Due to results the torque decreases with an increase in the tool rotation speed due to increases in the heat generation rate and temperature, but torque is not significantly affected by the change in welding speed. The computed pressure field was higher in front of the tool compared to the trailing edge, and it is because pressure difference is required for flow occur. According to the selected parameters in this study, maximum temperature was produced in 800rpm tool speed and the computed strain rate and pressure of workpiece in this speed were 2.3 s-1, 0635 MPa, respectively. تفاصيل المقالة
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        13 - Investigation into Aging Effect on Wear Behavior of Titanium Alloy
        امیر قیصریان محمود عباسی
        Ti-6Al-4V titanium alloy has great application in medicine and military industries due to its capabilities, namely high strength to weight ratio and corrosion resistance. In the current research, the effect of aging treatment on microstructure and wear behavior of Ti-6A أکثر
        Ti-6Al-4V titanium alloy has great application in medicine and military industries due to its capabilities, namely high strength to weight ratio and corrosion resistance. In the current research, the effect of aging treatment on microstructure and wear behavior of Ti-6Al-4V titanium alloy was investigated. Pin on disk wear test was applied to assess the wear behavior. Specimens were first solution treated at 950 C and 1050 C and then were quenched and aged. Some specimens were annealed before aging at 700 C. The results showed that aging treatment resulted in the hardness increase and the wear resistance decrease. It was also observed that annealing treatment before aging, enhanced the martensite decomposition and the formation of 2 particles, and correspondingly resulted in more hardness and lower wear resistance. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyses confirmed that presence of hard phase 2 particles within soft beta phase was the main reason for wear resistance decrease. تفاصيل المقالة
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        14 - Investigation of additive manufacturing of porous Ti-6Al-4V alloy: Geometry analysis for dental applications
        Mohammad Hossein Malekipour Esfahani Fatemeh Safdarian Sharif Heydari
        This research is dedicated to reviewing porous titanium alloy structures suitable for biomedical applications. The mechanical properties of porous samples with different structures and porosity were reviewed through a static compression test to identify the type of suit أکثر
        This research is dedicated to reviewing porous titanium alloy structures suitable for biomedical applications. The mechanical properties of porous samples with different structures and porosity were reviewed through a static compression test to identify the type of suitable structure. In addition, high porosity is desirable due to the growth of bone tissue in the internal microstructure of the porous bony implant. Samples are normally fabricated made of Ti-6Al-4V alloy and stainless steel using selective laser melting (SLM) as an additive manufacturing process. The samples were prepared with a pore size (200, 400, and 600 µm) and cubic and trabecular topology. The actual weight of all samples was determined, which is important in identifying other characteristics. All the tested samples reached the optimal values of maximum stress and tensile strength. The most appropriate mechanical properties were observed for samples with a pore diameter of 200 μm and a cubic structure. The implants with porosity, pore size, and pore interconnectivity affect the differentiation of bone tissue. تفاصيل المقالة
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        15 - Tolerance Analysis of the Trigger Mechanism Assembly Using Direct Linearization Method
        عبدالعلی مراثی محمد سالم
        Tolerance analysis of mechanical assemblies is an important tool in reliable design of products at low cost and good quality. Using this tool, it is possible in manufacturing stage to observe the effect of parameters on assembly requirements. The direct linearization me أکثر
        Tolerance analysis of mechanical assemblies is an important tool in reliable design of products at low cost and good quality. Using this tool, it is possible in manufacturing stage to observe the effect of parameters on assembly requirements. The direct linearization method is a useful method which runs based on vector loop analysis. In this research, the DLM method is used to analyze the tolerance chain in triggering mechanism assembly. Furthermore the percent contribution of various manufacturing dimensions on the design requirement of the assembly in determined. تفاصيل المقالة