Effect of vacuum hot pressing on the properties of ODS-HT9 steel

【Objective】 The objective of this paper is to prepare oxide dispersion strengthened (ODS) HT9 steel by vacuum hot pressing sintering, and to investigate the effects of different sintering temperatures and pressures on the mechanical properties, microstructure, phase composition and fracture morphology of the prepared ODS-HT9 steel.
【Method】 ODS-HT9 steel was fabricated via vacuum hot pressing sintering. The density, HV, tensile strength and elongation of sintered samples under different temperatures and pressures were tested. The effects of sintering parameters on microstructure, phase composition and fracture morphology of ODS-HT9 steel were analyzed by means of optical microscope, XRD and SEM.
【Result】 The increase of sintering temperature is beneficial to the adhesion of powder particles and the densification of samples. When the sintering temperature is 1 050 ℃, the relative density of the sample is the best, comprehensive properties are better, and the typical ductile fracture occurs. The hardness, tensile strength and elongation are 647HV, 916.1 MPa and 10.7%, respectively. With the increase of sintering pressure, the hardness, tensile strength and elongation of the samples increase gradually, and the density of the samples increases significantly. When the sintering pressure is more than 30 MPa, the increasing trend of density, hardness, tensile strength and elongation of the samples becomes slower.
【Conclusion】 Sintering temperature and pressure exert pronounced effects on the microstructure and mechanical properties of ODS-HT9 steel. Moderate elevation of sintering temperature and pressure facilitates powder bonding and material densification, which further enhances the mechanical performances of sintered specimens.