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针对灰铸铁激光熔覆的白口组织和开裂问题,研究了NiCuFeBSi合金材料及基体预热工艺对白口组织控制的影响,评价了合金力学性能。结果表明,NiCuFeBSi合金熔覆层界面白口组织宽度较小,基体预热温度升高时,白口组织呈现分散、断续状分布。半熔化区由于白口组织存在,显微硬度在此区达到峰值,向界面两侧呈递减趋势;NiCuFeBSi合金抗拉强度较高,横向抗拉强度大于纵向,其与HT250的对接试样抗拉强度受热影响区强度下降影响,强度小于NiCuFeBSi合金和HT250。熔覆层拉伸断裂机制为解理断裂为主、解理与准解理混合型断裂。
In order to solve the problem of cracking and whitening of gray cast iron by laser cladding, the effects of NiCuFeBSi alloy and preheating of matrix on the control of white mouth were studied, and the mechanical properties of the alloy were evaluated. The results show that the width of white mouth of NiCuFeBSi alloy cladding layer is small, and the distribution of white mouth is dispersed and intermittent when the preheating temperature of matrix increases. Due to the presence of white mouth, the microhardness peaked in this region and decreased toward the two sides of the interface. The NiCuFeBSi alloy had higher tensile strength and higher transverse tensile strength than the longitudinal direction, The strength is affected by the decrease of the strength of the heat-affected zone, and the strength is less than that of the NiCuFeBSi alloy and the HT250. The mechanism of tensile fracture of cladding layer is cleavage fracture, cleavage and quasi-cleavage mixed fracture.