Formation of the reversed austenite during intercritical tempering in a Fe–13%Cr–4%Ni–Mo martensitic stainless steel

Formation of the reversed austenite obtained by intercritical tempering has been studied via transmission electron microscopy (TEM) in a Fe–13%Cr–4%Ni–Mo low carbon martensitic stainless steel. It is found that the precipitation of M23C6 carbides along the martensite lath boundaries will result in Ni-enrichment in the adjacent region. The reversed austenite forms with the Ni-enrichment region as the nucleation sites, keeps a cube–cube orientation relationship with the M23C6 carbides and bears the Kurdjumov–Sachs (K–S) relationship with the martensite. Moreover, the reversed austenite formed inside the martensite laths is also confirmed. The mechanism for formation of the reversed austenite is discussed in detail.