Microstructures and mechanical properties of Ni60 alloy fabricated by laser metal deposition

Abstract

Due to its low melting point and high hardness, Ni60 (Ni–Cr–B–Si) alloy is widely used as surface cladding material for mould steel. In present study, Ni60 alloy thin-walled samples were fabricated using laser metal deposition (LMD) technology on H13 steel substrate which is usually used as mould material. The microstructure and mechanical properties (microhardness and wear resistance) of LMD Ni60 alloy were investigated. The results show that the LMD Ni60 alloy sample is mainly composed of Ni, Ni3Fe, Ni3B, Ni3Si, CrB, Cr5B3 and Cr7C3. The microstructures of the sample mainly include Ni–B–Si eutectics, Ni columnar dendrites and precipitates (boride and carbide). In the region with faster cooling rate of the sample, eutectics take a larger proportion, meanwhile precipitates are refined and dispersed uniformly. So hardness of the region can reach 950 HV. In the interlayer region, eutectics decrease while Ni dendrites increase because of the influence of remelting. The hardness of this region is about 750 HV. Wear resistance tests indicated that the wear resistance of LMD Ni60 alloy is about 9 times of H13 steel.