Diffusion welding of powder metallurgy high speed steel by spark plasma sintering

Abstract A diffusion welding of HS 6-7-6-10-0.1LaB6 powder metallurgy high speed steel (PMHSS) is successfully achieved by spark plasma sintering (SPS) for the first time in this research. The effect of welding process in terms of bonding temperature, pressure and time on microstructure evolution and tensile strength of the samples are studied in detail. Results indicate that the temperature plays a vital role on the welding quality. A complete welding can be obtained at 1100℃ within varied ranges of pressure and time. When welded at 1100℃, 30 MPa for 30 min, the tensile strength of the sample after heat treatment reaches 2183.5 MPa, higher than that of the base material, which is further confirmed by the subgrain strengthening effect in SPS from TEM analysis.