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. [ABSTRACT FROM AUTHOR]