Abstract: The maximum principal stresses, von Mises equivalent stresses in dissimilar welded joints between martensitic (T91) and bainitic heat-resistant steel (G102) with different welding creep strengths are simulated by using FEM under the conditions of 560 ℃ and applied stresses of 100 MPa, 120 MPa and 140 MPa. Simulation results are validated with accelerating test. The results show that the maximum principal stress is quite high in the vicinity of weld/G102 interface for undermatching joint, and creep cavities are easy to form in the weld/G102 interface. The maximum principal stress and von Mises equivalent stress in the vicinity of weld/G102 interface for overmatching joint are high, and creep cavities are easy to form and expand. The maximum principal stress and von Mises equivalent stress of weld/G102 interface for medium-matching joint are the least among the three joints. The interfacial creep damage of undermatching welded joint is very serious, the creep cavities of weld/G102 interface nearly link to form creep cracks in overmatching joint. The creep damage and early failure tendency of medium-matching joint are the lowest among the three joints, and only isolated cavities are found in the test. And the results of numerical simulation are consistent with those of experiment.

Key words: Bainitic heat-resistant steel, Dissimilar steel welded joint, Interfacial creep damage, Martensitic heat-resistant steel, Numerical simulation