Strategy of considering microstructure effect on weld residual stress analysis

Welding generates thermal distortion and residual stress, and it is well known that they affect the performance of welded structures by contributing to brittle fracture, fatigue, buckling deformation, and stress-corrosion cracking. Welding distortions and residual stresses can possibly be controlled and reduced by using countermeasures. Not only thermal stress behavior but also the prediction of the microstructural phase during welding heat cycles is very important. High-strength steels or martensitic stainless steels are used in many power plant components, and the effect of phase transformation on the mechanical behavior during welding of these steels becomes much larger than that of mild steels and austenitic stainless steels. Simultaneous simulations of the thermal stress and microstructure during welding are necessary for a precise evaluation. In this paper an analytical method and several applications using actual components are introduced in order to emphasize the effect of the microstructure on the weld residual stress analysis.