Transient and Residual Thermal Strain-Stress Analysis of GMAW

A three-dimensional transient thermomechanical analysis has been performed for the Gas Metal Arc Welding process using the finite element method. Because the heat generated due to elasto-visco-plastic straining in welding is negligible in comparison to the arc heat input, the thermomechanical analysis is uncoupled into two parts. The first part performs a three-dimensional transient heat transfer analysis and computes entire thermal history of the weldment. The second part then uses results of the first part and performs a three-dimensional transient thermo-elastoplastic analysis to compute transient and residual distortions, strains and stresses in the weld. The thermomechanical model incorporates all the thermophysical and mechanical properties of the material as functions of temperature. Boundary conditions used in the numerical simulation are quite general and are matched with the experiment carried out to measure transient strains in the mild steel (0.22 percent carbon steel) weld. Good qualitative agreement was achieved between calculated and measured transient strains.