Establishment and application of material models for numerical simulation of welding process

Temperature and temperature history dependent material model and temperature history dependent work hardening model were established based on the thermal-mechanical experimental results.The results of thermal-mechanical experiments indicated that material properties of aluminum alloy 5A06 during the cooling stage of typical thermal cycles followed one set of curves, which were different from those during the heating stage.The established models were applied in numerical simulation to study the evolution of stress during welding process more actually and predict the distribution of residual stress more accurately.Taking the work hardening effect into consideration, the different evolutions of yield stress led to the different evolutions of longitudinal stress.Yield stress of the material at the weld zone decreased a lot after having experienced weld thermal history and longitudinal compressive plastic strain at the weld zone recovered to some extent during the cooling stage.These are the main cause for the lower peak longitudinal residual tensile stress in history dependent models.