Complex-shaped high speed steel with high mechanical performance fabricated by gelcasting sintering

Abstract

Abstract Hot isostatic pressing is the most common method to prepare powder metallurgy high speed steel. However, due to the limitation of the steel capsule, it is still a challenge to directly produce complex-shaped high speed steel. Therefore, a gelcasting sintering process is proposed in this study. Complex-shaped high speed steel parts were prepared. First, fine powders (10 μm) were employed to prepare a gelcasting slurry. Then, the slurry was poured into a silicone mould followed by debonding and pressureless sintering. Nearly full densification was achieved in the gelcasting sintered samples. Homogeneous microstructure was observed with fine carbides (1 – 2 μm) evenly distributed in the matrix. Compared to traditional samples prepared by hot isostatic pressing, the bend strength increased from 2 800 MPa to 3 800 MPa. Additionally, the oxygen content of the sintered samples was lower than 100 ppm.