Abstract: Effects of different quenching processes on the microstructure and hardness of Cr26 high chromium wear resistant cast iron were studied by means of optical microscope and Rockwell hardness tester. The results show that the microstructure of as-cast Cr26 high chromium cast iron is mainly composed of primary austenite and carbide. After quenching and air-cooling at different temperatures from 980 ℃ to 1060 ℃, a large amount of secondary carbides are precipitated from the microstructure of high chromium cast iron. With the increase of quenching temperature, the secondary carbides precipitated in the microstructure first increase and then decrease, and the hardness of the specimen first increases and then decreases. The hardness of quenched specimens at 1020 ℃ reaches peak value, which is 65.7 HRC. When the high chromium cast iron quenched at 1020 ℃ in air, oil or water, carbide particles in the microstructure of high chromium cast iron, carbide proportion, and the hardness of the high chromium cast iron all increase gradually with the increase of cooling rate. The hardness of water quenched high chromium cast iron reaches the maximum value of 68.2 HRC.

Key words: Cr26 high chromium cast iron, quenching, microstructure, carbide, hardness