Welding-induced yield strength heterogeneity in X100Q: Modelling and characterisation

Yield strength (YS) heterogeneity in X100Q high strength low alloy (HSLA) steel welded joints is a key factor which influences fatigue life performance. The effects of welding-induced microstructural changes are investigated using a mechanistic YS model, which enables understanding of the key strengthening mechanisms which give rise to YS heterogeneity in X100Q. The model is used to predict YS in parent metal, physically-simulated fine-grain heat-affected zone material, and inter-critical heat-affected zone material, incorporating cooling rate effects. The model successfully predicts the measured welding-induced YS heterogeneity, with high-angle boundary (HAB) and precipitate strengthening mechanisms as dominant factors.