Reheating cracking susceptibility in the weld heat-affected zone of reduced activation ferritic-martensitic steels and the effect of Cr content

Abstract

Reduced activation ferritic–martensitic steels with different Cr contents were prepared to investigate the effect of Cr on the reheating cracking susceptibility in the weld heat-affected zone (HAZ). After HAZ simulation, stress-rupture tests were performed at 650–750°C, corresponding to the post-weld heat treatment temperature, using a Gleeble simulator. Increasing the Cr content markedly reduced the rupture ductility, resulting in an increase in the susceptibility to reheating cracking. This was attributed to the intergranular Cr-enriched M23C6 carbides that precipitated along the prior austenite grain boundaries during rupture testing, which acted as crack initiation sites. The size of these carbides increased with increasing Cr content, indicating that an increase in Cr contents easily facilitates formation and growth of microvoids that promote reheating cracking during rupture testing.