Effect of Quenching Process on Microstructure and performance of High-Boron High-Speed Steel

ABSTRACT

The effects of quenching process on microstructure and hardness of High-Boron High-Speed Steel (HB-HSS) containing 0.4%C-6.0%Cr-4.0%Mo-1.0%V-1.0%Si-0.5Mn-x%B-y%Al (x=1.0, 1.5, 2.0, y=1.0, 2.0, 3.0) were investigated by means of optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD), and Rockwell hardness tester. The experimental results indicate that the quenching microstructure of HB-HSS consists of α-Fe, M₂(B, C), M₇(B, C)₃ and a few of M₂₃(C, B)₆ 。With the increase of quenching temperature, the net structure of borocarbides is damaged and the borocarbides are evenly distributed in the matrix. When the quenching temperature is 1050 °C, the Rockwell hardness of HB-HSS increases with the increase of boron content. The Rockwell hardness of HB-HSS decreases with the increase of aluminum content. When the quenching temperature is 1050 °C, the aluminum content is 1.0% and boron content is 1.0%-2.0%, the combination of the microstructure and the hardness of HB-HSS is the best.

Keywords
High-boron high-speed steel; Quenching microstructure; Borocarbide; Hardness