Effect of quenching temperature on microstructure and properties of multivariate high chromium cast iron

The effects of different quenching temperatures on the microstructure and properties of 3.3C-20.0Cr-1.0W-0.5B-2.0V-1.8Mo (wt.%) high-chromium cast iron were investigated using an optical microscope, scanning electron microscope, X-ray diffractometer, Rockwell hardness tester, microhardness tester, and wear testing machine. The results show that the microstructure of as-cast multivariate high chromium cast iron mainly consists of eutectic carbides (M7C3), austenite and martensite matrix. In the process of quenching temperature increasing from 950 °C to 1150 °C, the morphology of massive eutectic carbide (M7C3) did not change. Acicular eutectic carbide (M7C3) appeared to aggregate and grow, and was distributed in the form of blocks or rods. Secondary carbides (M23C6) were precipitated in the matrix. The matrix is transformed from austenite to martensite, with a small amount of residual austenite. The hardness and wear resistance firstly increased and then decreased. The hardness of the 1100 °C × 1 h + fog-cooled high-chromium cast iron reaches a peak of 67.0 HRC, and the abrasion resistance increases by 37.0% compared with that of the 950 °C × 1 h + fog-cooled specimen.