Effects of cryogenic treatment on microstructure and abrasion resistance of CrMnB high-chromium cast iron subjected to sub-critical treatment

Effects of cryogenic treatment on the microstructure, and abrasion resistance of CrMnB high-chromium cast iron subjected to sub-critical treatment were investigated by optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD), and wear test. The results show that cryogenic treatment makes the alloy present a more refined and homogeneous matrix. In the course of sub-critical treatment followed by cryogenic treatment, the amount of precipitated secondary carbide was more than that in air cooling. Cryogenic treatment can further reduce the austenite content but cannot make retained austenite transform to martensite completely. After cryogenic treatment, the hardness and abrasion resistance of CrMnB high-chromium cast iron can be improved obviously due to the precipitation of carbides, the martensite transformation, and a refined microstructure resulting from cryogenics treatment.