Achieving excellent properties in high-speed steel by hot isostatic pressing and heat treatment using PREP and EIGA powders

Abstract

The powder metallurgy T15 high-speed steels (PM T15 HSS) with the powders of plasma rotating electrode process (PREP) and electrode induction-melting inert gas atomisation (EIGA) were successfully prepared by hot isostatic pressing (HIP) at 960°C (960-EIGA), 1130°C (1130-EIGA, 1130-PREP) and 1200°C (1200-EIGA), respectively, and the effect of heat treatment (HT) including quenching and tempering on PM HSS has been studied. The microstructures including the average size, sphericity and volume fraction of the carbides, the mechanical properties and wear properties were visibly modified after HT. The hardness of more than HRC67, the fracture toughness of exceeding 25 MPa·m^1/2, the wear depth of 0.644 μm, the width of 0.455 μm and the wear rate of 0.98 × 10⁻⁶ mm³·N⁻¹·m⁻¹ were achieved in PM HSS after HT. Mechanisms about microstructure evolution and strengthening were discussed. The total strengthening contributions of 613 MPa for grain boundary strengthening of ∼173 MPa, carbides strengthening of ∼244 MPa and solute strengthening of ∼196 MPa were calculated for 1130-EIGA. The current study offers ideas for the high performance of HIP and HT samples can be implemented equally by high-quality PREP and EIGA powders.