Effect of Aluminum Content on Microstructure and Tempering Precipitation of High Boron High Speed Steel

Author of the article:CHEN Hantao1 , MA Shengchao2 , LUO Yang1 , WANG Jie1 , XING Jiandong1 , MA Shengqiang1

Author's Workplace：1. Xi'an Jiaotong University, State Key Laboratory for Mechanical Behavior of Materials, Xi'an 710049, China; 2. Avic Shaanxi Aero Electric Co., Ltd., Xingping 710065, China

Key Words：high-boron high-speed steel; boron carbide; primary phase; secondary phase

Abstract：Aluminum element is an important addition element in M2 high speed steel, which can improve the tempering stability and oxidation resistance at high temperature. The effect of aluminum on microstructure and tempering property of high boron high speed steel was studied by adding different contents of aluminum. The results show that the microstructure of high speed steel containing Al and boron is composed of ferrite, pearlite and boride. An appropriate amount of aluminum promotes the formation of ferrite and pearlite, while too much aluminum leads to the formation of coarse primary borides. After quenching and tempering, the addition of a small amount of aluminum promotes the dispersion precipitation of high hardness nano-scale M6(C,B) and M(C,B), which significantly improves the precipitation effect of high boron high speed steel.