Effects of Post-Weld Heat Treatments on the Residual Stress and Mechanical Properties of Laser Beam Welded SAE 4130 Steel Plates

Abstract

The distribution of the residual stresses in laser beam welded SAE 4130 and the effect of stress relief after various post-weld heat treatments (PWHT) were measured by using the x-ray diffraction method. The mechanical properties and microstructure were also examined. Experimental results show that the tensile residua] stresses increased with the heat input of the laser beam. Most of the residual stresses were relieved by PWHT at 530°C for 2 hours followed by furnace cooling to 50°C. The strength of the as-welded samples decreased in comparison with the base metal. The yield strength of the weldment increased after PWHT at 320°C for 2 hours in comparison with the as-welded sample. The elogation of the laser beam welded samples increased after PWHT in comparison with the as-welded samples.