The effect of carbide distributions on long-term creep rupture strength of SUS321H and SUS347H stainless steels

The creep fracture mode and long-term creep rupture strength have been investigated for SUS321H and SUS347H austenitic stainless steels. During creep, fine TiC and NbC precipitated in the matrix of the SUS321H and SUS347H steels, respectively, accompanying the re-dissolution of previously precipitated M23C6 along grain boundaries, which accelerated grain boundary sliding and surface cracking. The creep rupture strength correlated with the stability and number density of grain boundary carbides.