Effect on microstructure and properties of carbon-free high-speed steel via hot isostatic pressing and subsequent heat treatment

Fe-Co-Mo carbon-free high-speed steel bulk materials were fabricated using hot isostatic pressing (HIP) in this study. The effect of heat treatment processes on its microstructure and properties was investigated. The microstructure of matrix and the precipitation behavior of intermetallic compounds in different conditions were characterized using techniques such as SEM, EBSD, and TEM, and mechanical properties were conducted on its hardness and three-point bending strength. The results indicate that the HIP temperature and annealing temperature significantly influence the microstructure and properties. Fe-Co-Mo carbon-free high-speed steel prepared at a HIP temperature of 1200 °C and an annealing temperature of 900 °C exhibited finer precipitated phases with a more uniform and dispersed distribution. After subsequent quenching-tempering heat treatment, the material achieved a microhardness of 878.3 HV and a three-point bending strength of 2988 MPa. This research provides valuable theoretical guidance for the development of novel Fe-Co-Mo carbon-free high-speed steel materials.