Microstructure and properties of modified Al-bearing high boron high-speed steel

This paper studies the best tempering process and provides guidance for the industrial application of modified Al-bearing high boron high-speed steel (AB-HSS) in the future. The microstructure, hardness and wear resistance of modified AB-HSS after quenching at 1150 °C and tempering in the different condition were investigated. The results showed that the matrix of modified AB-HSS consisted of tempered martensite after once tempering at 500 °C and 530 °C for four hours. Small granular secondary M₂₃(C, B)₆ type borocarbides were precipitated from the matrix. With the increase of tempering temperature, the macro-hardness, micro-hardness and wear resistance of modified AB-HSS all decreased gradually. With the increase of tempering times and tempering holding time, a part of tempered martensite was decomposed into ferrite, and the macro-hardness and micro-hardness all decreased slowly. Appropriate tempering process of modified AB-HSS was once tempering at 500 °C–530 °C for four hours.