Pouyan Namdar, Hamed Saeidi Googarchin, Seyed Hooman Ghasemi,
Volume 12, Issue 1 (3-2022)
Abstract
In this paper, mechanical properties of welded single lap joints of pure aluminum sheets produced by severe plastic deformation (SPD) are considered. SPD in form of a large pre-strain was imposed to aluminum sheets through the constrained groove pressing (CGP) process. Furthermore, CGPed specimens are joined using the resistance spot welding (RSW) method. Welding time and force are maintained evenly. Welding current is raised until ideal failure mode is observed. Finally, mechanical properties of fusion zone, heat affected zone (HAZ) and base metal of welded SPDed specimens are derived. The results show that by increasing the pre-strain in specimens, an improvement in yield strength, ultimate tensile strength, load carrying capacity, maximum displacement before failure and nugget diameter is observed. Furthermore, sensitivity of these parameters to CGP pass number is considered. Finally, it has been shown that fusion zone and HAZ hardness values can increase by increasing the CGP pass number.
Dr Moslem Mohammadi Soleymani, Benyamin Sohrabinejad, Dr Aliakbar Majidi Jirandehi,
Volume 14, Issue 2 (6-2024)
Abstract
In the automobile sector, stainless steel and resistance spot welding (RSW) are often used. In this work, RSW was used to join five samples of 316L stainless steel joints at currents of 15, 20, 25, 30, and 35 kA while the heat input parameters varied. The welded joints' microstructure, hardness, and mechanical properties were examined and evaluated. The base metal, heat-affected zone (HAZ), and weld areas' microstructures were all examined using optical microscopy. The mechanical characteristics of the joints were assessed using room-temperature tensile-shear testing and hardness testing. The microstructure findings revealed ferrite in many weld regions and an austenitic structure overall. In the samples with welding currents of 15, 20, 25, 30, and 35 kA, the average hardness of the weld zone was 329, 258, 251, 238, and 235 Vickers, in that order. The hardness of the weld zone exhibited an inverse connection with the welding current, as an increase in welding current resulted in a drop in the resistance spot welded area's hardness. Furthermore, when heat input increased, the hardness of the HAZ reduced and increased relative to the 316L steel. The joint strength of the RSW increased with increasing welding current, as demonstrated by the tensile-shear test results for all five welded samples with varying currents. As a result, the samples with 30 and 35 kA currents failed at the weld with a force greater than 3 kN, while the other samples with lower welding currents had a failure force of less than 2 kN.
