Numerical simulation of residual stress in 10Ni5CrMoV steel weldments

Numerical simulation and experimental tests are conducted to determine welding residual stresses of 10Ni5CrMoV ferritic high strength steel. Effects of cyclic hardening law and phase transformation on numerical simulation of residual stresses have been studied. The calculated residual stresses have been compared with measurements by the hole-drilling method and the X-ray diffraction method. Experimental results have shown that the material exhibits hardening in monotonic loading but softening in cyclic loading. The combined kinematic-isotropic hardening law and the kinematic hardening law give lower residual stresses predictions than the isotropic hardening law. Volume change due to martensite phase transformation has a crucial influence on residual stresses predictions, whereas the effect of yield stress change during cooling is negligible. The combined kinematic-isotropic hardening constitutive law along with consideration of phase transformation gives the most accurate prediction and is recommended for improving simulation accuracy for 10Ni5CrMoV steel. The effectiveness of the recommended procedure is validated by application to a multi-layer and multi-pass weld.