Microscopic Study of Carbide Precipitation during Heat Treatment of 35Cr–4C High Chromium Cast Iron

The carbide precipitation behavior of 35 wt%Cr–4 wt%C (35Cr–4C) Hypereutectic High Chromium Cast Iron (HHCCI) during heat treatment was investigated by means of scanning electron microscope and transmission electron microscope, and the effect of rare earth magnesium (RE-Mg) modification on the microstructure evolution and wear resistance of 35Cr–4C cast iron was also studied. The as-cast structure of 35Cr–4C HHCCI is mainly composed of primary carbides, eutectic carbides and austenite matrix. After quenching, there are secondary carbides M7C3 and M23C6 precipitation in the martensite matrix. After tempering, more secondary carbides will be formed and the main precipitate phase is M23C6. After heat treatment of RE-Mg modified HHCCI, more secondary carbides are precipitated, and the distribution in the matrix is more uniform, and the wear resistance is higher than that of unmodified HHCCI.