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Showing 2 results for Mohammadi Zahrani
Effect of heat treatment on the grain structure and mechanical properties of Al-7075 friction stir weld
M. Mohammadi Zahrani, M. Shamanian,
Volume 2, Issue 2 (Journal OF Welding Science and Technology of Iran 2016)
Abstract

The fine grain structure of friction-stir welded aluminum alloys is unstable during post weld heat treatment and some grains abnormally grown. In this study, the sequence of abnormal grain growth during T6 heat treatment of Al-7075 friction-stir weld and its effect on mechanical properties of the weld was studied. The results showed that heat treatment in 510 ˚C resulted in drastic grain growth in stir zone and fine equiaxed grains in the stir zone of as-welded joint were substituted by millimeter-scale irregular grains. Post weld heat treatment resulted in decrease in the tensile elongation from about 10% to 1.5% although the joint tensile strength improved by 28%. In addition, post weld heat treatment changed the fracture location from the 
heat-affected zone to the stir zone.


Microstructure and mechanical properties of similar and dissimilar welding joints of weathering steel and plain carbon steel by GMAW with CO2 shielding gas
M. Vatandoost, E. Mohammadi Zahrani, B. Beidokhti, A. Davoodi,
Volume 8, Issue 1 (Journal OF Welding Science and Technology 2022)
Abstract
The welding joints were investigated due to the significance of similar welding of Corten A weathering steel and its dissimilar welding with St12 plain carbon steel in industrial applications. The gas metal arc welding (GMAW) technique with carbon dioxide shielding gas was utilized in the present work. The welding process comprised current and voltage control, welding wire injection rate, shielding gas rate, welding speed, connection configuration, and microstructure evolution. Mechanical properties and microstructure evolution in similar and dissimilar joints and weld defects were evaluated by tensile, bending, hardness, metallographic, and radiographic tests. The weld microstructure in similar and dissimilar joints included grain boundary ferrite, acicular ferrite, and WidmanStatten ferrite. The tensile strengths of the similar and dissimilar joints were respectively 497 and 303 MPa. The weld zone hardness was 210 and 180 Vickers for similar and dissimilar joints, respectively. In conclusion, similar welding outperformed dissimilar welding considering weld joint defects, mechanical properties, and microstructure.
 

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