Prediction of creep deformation and rupture behaviour of 2.25Cr-1Mo weld joint

The evaluation of the creep properties of 2.25Cr-1Mo steel base metal, weld metal and weld joint at 773, 823 and 873 K over a stress range 80-300 MPa was carried out. The weld joint exhibited significantly higher creep rate a nd lower rupture life and ductility than the base metal and weld metal. Cre ep tests were performed on the simulated heat affected zone (HAZ) structure s of the weld joint (viz. coarse-grain bainite, fine-grain bainite and inte rcritical structure) at 823 K. The coarse-grain bainitic HAZ possessed high er creep strength and the intercritical HAZ possessed lower creep strength than the base metal and weld metal, whereas the fine-grain bainitic HAZ exh ibited creep strength comparable to that of the base and weld metals. A mod ified composite model with an interaction parameter was used successfully f or estimating the weld joint properties from the properties of the constitu ents of the joint. Properties estimated were steady state creep rate, ruptu re life and rupture ductility. (C) 2001 Elsevier Science Ltd. All rights re served.