Effects of temperature-dependent material properties on welding simulation

Detailed three-dimensional nonlinear thermal and thermo-mechanical analyses are carried out using the finite element welding simulation code––WELDSIM [Chao et al., In: Advances in Computational & Engineering Science, vol. II, Tech Science Press: Paledale, USA: 2000. pp. 1206–1211]. The objective is to investigate the effect of each temperature-dependent material property on the transient temperature, residual stress and distortion in computational simulation of welding process. Welding of an aluminum plate using three sets of material properties, namely, properties that are functions of temperature, room temperature values, and average values over the entire temperature history in welding, are considered in the simulation. Results show that (a) the thermal conductivity has certain effect on the distribution of transient temperature fields during welding, (b) the yield stress and Youngʹs Modulus have significant and small effects, respectively, on the residual stress and distortion, after welding, and (c) except for the yield stress, using material properties at the room temperature gives reasonable predictions for the transient temperature fields, residual stress and distortion. Since high temperature material properties are either difficult to obtain or do not exist for many materials, an engineering approach is proposed based on the results in this study. The engineering approach suggests using simplified properties constituted by a piece-wise linear function with temperature for the yield stress and constant room-temperature values of all other properties for computational weld simulation.