In-situ VN reinforced powder metallurgy M30 steels prepared from water atomized powers via pressureless sintering

In this paper, in-situ VN reinforced powder metallurgy high-speed steel was fabricated from water atomised powder via pressureless sintering. During sintering, N would replace C to react with V, resulting in the formation of in-situ VN phase. According to the first-principles calculations, the formation energy of VN was – 9.45 eV while that of VC was – 9.08 eV. The relative density of as-sintered samples reached up to 99%. Homogeneous microstructure and fine reinforced phases were obtained. Ultrafine VN phase (0.5 μm) was uniformly distributed in the matrix. As a result, the mechanical properties were improved. The optimal mechanical performance was obtained in the sample with 1.0 wt.% C addition. The hardness, bend strength and impact energy were 65 HRC, 3011 MPa and 18–22 J, respectively. Besides, the sintering window significantly increased from ∼10 to 30∼50°C.