Microstructure and abrasive wear properties of high carbon medium chrome wear resistant alloy steels after heat treatment （1）
Ning Jiapei, Zheng Kaihong, Zhou Hongming, Wang Haiyan, Long Jun)
(1. School of Materials Science and Engineering, Central South University, Changsha, Hunan 410083, China;2.Guangdong Institute of Materials and Processing, Guangzhou 510651, China)
Abstract: The effect of quenching temperature on microstructure and mechanical properties of medium chromium wear resistant alloy steel was studied. The mechanical properties and wear resistance of medium chromium alloy steel with different carbon content after heat treatment were tested, and the wear mechanism was analyzed. The results show that in the temperature range of 860-1020 °C, the increase of quenching temperature will make the grains grow up, and the carbides dissolve gradually. After being annealed at 1000 °C, quenched at 980 °C, and tempered at 220 °C, the microstructure of high carbon medium wear-resistant alloy steels containing 1.0% C is mainly lamellar martensite with a large amount of M7C3 type carbide particles uniformly distributed, high impact toughness and excellent abrasive wear properties.
Keywords: Wear-resistant alloy steel; quenching temperature; abrasive wear; martensite; M7C3
Alloy Steel has been used for more than 100 years. According to the different alloy elements added, different mechanical properties, and wear properties can be obtained.
Wear-resistant alloy steel is a kind of special performance steel used under different wear conditions. Many wear-resistant steels have been developed in China, such as austenitic manganese steel, medium chromium steel, and high carbon martensite steel. Because medium chromium steel has good hardenability, high wear resistance can be obtained by tempering after air quenching. At present, medium chromium steel is mainly low and medium carbon. The research shows that increasing the carbon content of medium chromium steel can improve its hardness and wear resistance after quenching. Hu Yichuan studied the microstructure and mechanical properties of high carbon medium chromium alloy steel (0.75% C, 4% CR) at different quenching temperatures (900-1000 °C), the wear resistance alloy steel is the best at 900 °C.
In order to further improve the wear resistance of medium-sized saw alloy steel, the carbon and chromium contents of medium-sized chromium alloy steel were increased, and other trace alloy components and heat treatment process were redesigned, the effects of the heat treatment process and carbon content on microstructure, mechanical properties and wear resistance were studied.
1.1 Composition of alloy steel
In order to improve the wear resistance of medium chromium alloy steel, it is necessary to design the composition of wear-resistant alloy steel with high carbon content to make it hard enough, and chromium can form M7C3 or M23C7 carbides in the steel. Molybdenum can refine the grain of steel and improve the hardenability. Nickel can improve the strength of steel and keep good plasticity and toughness. Simultaneously, the ternary alloying of CR, Mo, and Ni can improve the stability of austenite and prevent the formation of a bead/night body transition. The composition of the designed wear-resistant alloy steel is shown in Table 1.