Material hardening model effects on the calculated welding residual stresses in ultra-high strength steel S960

A reasonable material hardening model (MHM) should be determined for the accurate prediction of welding residual stresses (WRS) in numerical simulation. The present study methodically investigated the impact of material laws on the simulated residual stresses in ultra-high strength steel S960 weldments. Furthermore, mechanical tensile tests were performed to obtain the stress-strain curves and welding experiments were carried out to determine thermomechanical results for validation. The numerical and experimental results express that the amount of strain hardening for ultra-high strength steel S960 is very low at room temperature (RT) and high temperatures, while that is non-ignorable at medium temperatures such as from 200 to 500 °C here. The applied material plasticity model has almost no influence on the computed longitudinal residual stress in numerical simulation of S960 steel. Nevertheless, the predicted magnitude of transverse residual stress could be slightly affected by the employed MHM. For ultra-high strength steel S960, the perfect-plastic (non-hardening) model can accurately predict WRS, which is recommended to use in numerical simulation.