Creep Behaviour of 9Cr-1Mo Similar and Dissimilar Weld Joints

摘要

Evaluation of the creep behaviour of 9Cr-1Mo base metal, 9Cr-1Mo / 9Cr-1Mo similar weld joint and 9Cr-1Mo / Inconel 182 / Alloy 800 dissimilar weld joint at 823K over a stress range of 100 - 250MPa has been carried out. The weld joints were given a post weld heat treatment (PWHT) of 973K for 1 hour. A hardness trough was observed in the intercritical heat affected zone (HAZ) in 9Cr - 1Mo steel of both the weld joints; whereas a maxima in hardness was seen at the diffuse weld interface of dissimilar weld joint. Both the weld joints exhibited lower rupture lives compared to the 9Cr-1Mo base metal. The weld joints exhibited comparable rupture life at higher applied stresses. At lower stresses the dissimilar weld joint displayed lower rupture life than the similar weld joint. Creep failure in similar weld joint occurred in the intercritical HAZ in 9Cr-1Mo steel. At higher stresses the failure in dissimilar weld joint occurred in the intercritical HAZ of 9Cr-1Mo and at lower stresses at the weld interface. Creep cavitation was prevalent at the weld interface region of the dissimilar weld joint specially at lower applied stresses.