Compound casting refers to a process that used to produce bimetals. This study investigates the interface of Mo40/C93200 that is produced by compound casting process. In this research, molten bronze is poured around steel core, interaction between liquid and solid creates a diffusion zone and followed by a transition layer which leads to the creation of diffused region between the interfaces of metal layers. The results of micro-hardness and macro hardness used to complete the studies. The results of the hardness of the Mo40 alloy revealed that the micro-hardness of the alloy was almost 308 Vickers which this amount of hardness confirms the ferrite-pearlite state of microstructures. The results of metallography revealed that the boundary between steel and bronze alloys due to the difference in electric potential during etching evolved a galvanic cell and one section formed as the cathode and the other section as the anode. In this situation steel was corroding and bronze was protecting. As well as, the results of SEM show that the boundaries between two alloys have an acceptable adhesion and the strength of interface is sufficient. The result of tensile test indicates that the final yield strength was about 800 MPa and the elongation increases by 2%, which is an acceptable value. It is also observed that the failure is a soft defect type and a sufficient connection between steel and bronze is formed. پرونده مقاله

In any case, macroscale shaping cannot be transferred to microscale due to the size effect. There are different parameters to evaluate small-scale forming. In this article, the effect of flow stress and topography in two states of lubrication and without lubrication for T2 copper micro cylinder has been investigated using the numerical solution and prediction of a trained neural network. An artificial neural network model has been presented to investigate the flow stress and the effect of friction with the miniaturization of the copper microcylinder. The results show that the flow stress decreases with decreasing the initial specimen diameter in both lubrication conditions, and the flow stress decreases by 30 MPa with the initial specimen diameter decreasing from 8 mm to 1 mm. The friction factor increases obviously with decreasing the initial specimen diameter in the case of lubricating with castor oil, and the friction factor increases by 0.11 with the initial specimen diameter decreasing from 8 mm to 1 mm. However, the tribology size effect is not found in the case without lubrication. The reasons for the flow stress and tribology size effects were also discussed. The good matching of outputs and objectives in the regression graphs shows that the response of the neural network is satisfactory. پرونده مقاله

Metal spinning as a kind of manufacturing process has capability to shape hollow components. In present work shear spinning process is used to formplates into conical shapes. Moreover, the aim of this research is to demonstrate the impact of the process parameters (i.e. feeding rate and spindle speed) on wall thickness. This approachwas done by experimental and finite elements method. The results illustrated that wall thickness decreases while feeding rate increases in spinning process. The experimental results confirm the Finite element analysis (FEA) results during thickness evaluations so this shows that FEA results are reliable for this specific case. The results of analysis reveals that the best condition for spinning is for feeding rate of 40 mm/min and spindle speed of 50 rpm in which highest thickness of 1mm is obtained. In consequence, the findings also illustrated that by decreasing the feeding rate and spindle speed, higher thickeners can be observed during shear spinning process. پرونده مقاله

Nowadays, the role of light weight materials has grown up in important industries such as aerospace and biomechanics, but before the appliance, their strength should be increased. A modern way to increase this factor along with the lightweight factoris using bimetal sheets, hence, the design of multilayer sheets has been very much considered recently. In this study, explosive welded Cu/St/Cu multilayer sheets were used in the incremental forming process to determine the springback phenomenon on different layers. The results indicated that rotational speed, feeding rate, and vertical step parameters can affect spring back in single point incremental forming process (SPIF).Three levels of vertical step size, tool rotational speed, and feed rate have been considered as the input process parameters and spring back as the output.In order to design a better experiment and analyze the data, the Taguchi method was selected on the basis of DOEin Mini-Tab software andthe results have been analyzed by two states. In the first state,the value which was closest to the nominal value is considered to be the optimal result which obtained for spring back angles with parameters of 0.75 mm for the vertical step down, 200 rpm for the rotational speed and 500 and 1000 mm/min for the feeding rate. In the second state, the least amount is considered as the optimal result in which the values of 0.5 and 1 mm of the vertical step down, 150 and 100 rpm of the rotational speed, and 1500 and 500 mm/min of the feeding rate formed the optimal outcome. پرونده مقاله

Equal channel angular rolling (ECAR) process is one of the severe plastic deformation (SPD) methods that have been used to make ultra-fine grain (UFG) materials with improving the mechanical properties of samples. After performing the process at several paths, a large strain is applied to the material that can cause decreasing the grain size and improving the mechanical and physical properties of the metal. In this paper, the effects of annealing thermal treatment at various temperatures and times on the weld bond of bimetal explosive welded stainless steel-copper sheet during the equal channel angular rolling process have been investigated. For this purpose, after performing the ECAR process and thermal treatment on bimetal sheet, hardness and welding interface were studied. The results showed that performing thermal treatment at different temperatures caused the formation of intermetallic compounds in the weld bond, which would change the hardness of this region. Also, increasing the annealing time increased the thickness of the weld bond. پرونده مقاله

Equal channel angular rolling (ECAR) process is one of the methods that have been used to make ultra-fine materials by imposing severe plastic deformation. After repeating the process several times, a large effective strain is applied to the sample that can cause decreasing the grain size and improving the mechanical and physical properties of the metal. In this study, thermal conductivity of the samples that were produced by ECARwas investigated experimentally. Accordingly, the strips of aluminum alloy 3003 were ECARed up to 10 passes through route-A and route-C. The effect of number of ECAR pass and routes of ECAR process (A and C) were investigated. Furthermore, tensile behavior and micro-hardness of ECARed samples werestudied.According to the results,the thermal conductivity of samples increased up to definite pass and raised to its maximum value, then had an oscillatory trend up to tenth pass. Although this improvement of the thermal conductivitywasn’t significantly, but the improvement of yield and ultimate strength and micro-hardness of the samples in passes associated with the maximum thermal conductivity, were meaningfully and so,this ECARed alloys can be used in harder situation. پرونده مقاله

Equal channel angular rolling (ECAR) is a severe plastic deformation method that covered plastic deformation of sheets. In this study, effects of ECAR route shave been investigated on the mechanical and microstructure properties of explosive-welded Al-Cu bimetal. At first, the explosive welding process has been performed to prepare the Al-Cu bimetals. Then, to relieve the stress and preparing of samples for ECAR process, the annealing process of the samples was done. Finally, the ECAR process was performed on the samples in two routes A and C. Results showed that yield and tensile strengths and micro hardness of ECARed samples significantly increased with increasing the number of passes, whereas their ductility decreased. The yield strength of bimetals has been increased from 80 MPa to 100 MPa and 130 MPa at the routes A and C, respectively. Also, with increasing the number of ECAR passes, the grain size of the ECARed bimetals decreased to about 2μm. پرونده مقاله