Abstract: The creep strain distribution in the low strength material adjacent to weld interface of dissimilar heat-resistant steel welded joint is investigated by finite element method, and the mathematical model between the stress triaxiality (σav/σ) and the ratio of creep strain rate (εw/εb) is established. It was shown from the analytical result that the stress triaxiality in the creep restraint zone (CRZ) of low strength material adjacent to the interface is a major mechanical factor of low-ductile creep fracture for the welded joint. The theoreticl analysis agrees with the creep fracture test results.

Key words: Dissimilar steel welded joint, Low-ductile creep failure, Stress triaxiality