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Showing 3 results for Kazemi
Simulation of effective parameters on low-carbon steel laser welding process using finite element method
M. E. Kazemian, F. Mohsenifar, R. Ghanbarzadeh,
Volume 3, Issue 1 (Journal OF Welding Science and Technology of Iran 2017)
Abstract
In this paper, laser beam welding of a rectangular piece of steel was simulated using Fluent software. Physical properties of analytical field was constant and its changes with temperature was ignored. In the present work, effect of tool speed and laser power on temperature distribution of workpiece surface and different deeps in the plane of symmetry and also maximum of temperature and depth of penetration were investigated. Using a macro code, geometry generation and meshing of the analytical field by helping required geometric  parameters were provided for software. Moreover, laser radiation power was exerted by writing an UDF in the fluent software. In this case, it was assumed that the workpiece is stationary and gaussian thermal source model defined in UDF moves with the intended speed. Results show that at a constant power, maximum temperature of the workpiece decreases with increasing heat source speed, moreover, in this case, gradient of temperature in front of the workpiece and behind of it, increases and decreases respectively. It is found that the temperature in the depth of the workpiece increases with increasing the power.
The effect of rotation speed to traverse speed ratio and number of welding passes on thermo-mechanical stability of severely plastic deformed aluminum joined by friction stir welding and graphite/Al2O3 hybrid powder
S.e. Moosavi, M. Movahedi, M. Kazeminezhad,
Volume 8, Issue 1 (Journal OF Welding Science and Technology 2022)
Abstract
In this study, thermo-mechanical stability of two-pass constrained groove pressing (CGP) AA1050 sheets towards friction stir welding (FSW) employing hybrid powder (%50vol. micrometric graphite powder+%50vol. α-Al2O3 nanoparticles) was investigated by examining its microstructural evolutions and mechanical properties. FSW was carried out via different process variables in order to reach the highest ultimate mechanical properties of joints. The welding variables employed in this study were single-pass and multi-pass FSW, and different rotation speed to traverse speed ratios (ω/v) were. In order to appraise the powder effect on mechanical properties in the fabricated hybrid metal matrix composite (HMMC), some CGPed sheets were also welded with no powder. Besides optical microscopy and field emission scanning electron microscopy (FESEM) observations, Vickers microhardness and transverse tensile tests were conducted to examine mechanical properties of the weld zone. It was revealed that the effect of graphite powder as a solid lubricant was substantially influenced by the welding variables. More precisely, by employing graphite powder during the FSW, the peak temperature decreased to 224 ℃, while the peak temperature of 489 ℃ was resulted by welding without any powder. Thus, the thermo-mechanical stability of CGPed aluminum and their mechanical properties were enhanced. On the other hand, graphite powder can be responsible for mechanical properties drop due to deteriorating material flow. In addition, different strengthening mechanisms, including grain boundary Zener-pinning and particulate stimulated nucleation (PSN) mechanism, were provided and governed by both powders. However, increasing the ω/v ratio was a practical approach to obtain uniform powder distribution, and consequently, to attain ultimate mechanical properties. Moreover, weld soundness was perceived to be achievable by increasing the number of FSW passes due to eliminating the cavities and improved material flow, resulting in an ultimate tensile strength of 101 MPa, as an optimum efficiency of ~ %80, in three-pass FSW at ω/v=70.
 

Investigation of Mechanical Properties in Welding of Stainless Steel SA240-TP316 and Steel SA516-GR60 Cladded with Stainless Steel SA240-TP316
S. Kazemi, G. Khalaf, A. Afsari, M.j. Marzban,
Volume 8, Issue 2 (Journal OF Welding Science and Technology 2023)
Abstract
Stainless steel cladding is the formation of an alloy by creating a thin layer of stainless steel on another metal. In this research, a layer of SA240-TP316 austenitic stainless steel was coated on SA516-GR60 steel. Experiments were conducted to compare the mechanical properties of SA240-TP316 and claded SA516-GR60 steel welds in order to investigate the possibility of replacing the SA240-TP316 steel alloy. Examining the results of the chemical analysis of SA240-TP316 alloy shows that the coating has a similar chemical composition to SA240 alloy and with increasing depth, the hardness of the weld metal and the percentage of chromium is higher and the percentage of molybdenum in the weld alloy is lower. Comparing the ultimate strength of SA516 alloy after cladding and welding with SA240 stainless base alloy shows the improvement of tensile strength. In the first case, the strength changes in the range of 470 to 503 MPa and in the second case in the range of 477 to 570 MPa. The highest hardness was obtained in the heat affected area. Bending test showed that bending without cracking up to 180 degree angle is a sign of weld metal remaining ductile. The results of the impact test also show the ability to absorb energy, especially around the voltage of 150 volts.

 

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