Failure mechanism of HR3C austenitic steel during creep at 650°C

Abstract

AbstractThis paper investigates the intergranular failure and degradation process of HR3C steel during creep. Substantial microscopic information for the morphological and compositional characteristics of intergranular precipitates were revealed here. The results showed that the intergranular M23C6 carbides precipitated progressively, resulting in a formation of Cr‐depleted region, and coexist with the NbCrN phase at the grain boundary. Besides, the dislocation configuration and density of HR3C steel also changed remarkably after creep, which manifests that the increase of lattice debonding extent and irregular atoms array. The intergranular damage of the M23C6 matrix interface was revealed by the HRTEM observation, and the main damage features were the volumetric defect generation as well as the large‐area distortion of atom lattice around the M23C6, which would contribute to the intergranular crack forming at the end of creep stage.