刀具表面SLM制备镍基合金涂层组织及磨损性能分析

Microstructure and Wear Property Analysis of Nickel Base Alloy Coating Prepared by SLM on Tool Surface

对刀具用304奥氏体不锈钢表面进行选择性激光熔化成形Ni60涂层,通过试验测试的手段研究熔覆层硬度、抗磨损能力与耐腐蚀性的差异性。研究结果表明,涂层底部主要存在平面晶和胞状晶形态组织,涂层中部主要包含大量的鱼骨形态柱状晶,涂层顶部在深度达到200μm附近生成了许多小尺寸等轴晶。Ni60涂层顶部硬度最大达到710.2 HV,均值达到593.1 HV,与基材相比增大了近2倍。涂层和基体分界部位达到252.3 HV的硬度值,与涂层硬度均值相比显著降低。Ni60涂层摩擦系数均值为0.08,形成硬度很大的表面,表面达到比基材更优的润滑性能。Ni60涂层磨损后形成了很细的磨痕,并未出现明显剥落与塑性变形,磨损量达到3.2×10^(-5)mm^(3)/(N·m),比基材降低了一个数量级。该研究对提高刀具的耐磨性能以及使用寿命具有很好的理论价值,易于推广应用。

Ni60 coating was obtained by laser cladding on the surface of 304 austenitic stainless steel used for cutting tools.The hardness,wear resistance,and corrosion resistance of the cladding layer were studied by experimental testing.Results showed that there are mainly planar and cellular crystal structures at the bottom of the coating,a large number of columnar crystals in the middle of the coating,and many small-sized equiaaxial crystals appear near the depth of 2o0μm from the upper layer.The maximum hardness at the top of Ni60 coating is 710.2 HV,with an average of 593.1 HV,which is nearly two times higher than that of the base material.The hardness of the boundary between coating and substrate reaches 252.3 HV,which is significantly lower than the average hardness of coating.The average friction coefficient of Ni60 coating is 0.08,which forms a surface with great hardness and better lubrication performance than the base material.Finer wear marks occur on the Ni60 coating after abrasion,without obvious spalling and plastic deformation.The abrasion loss is 3.2X10^(-5) mm^(3)/(N·m),which is lower than the base material by an order of magnitude.The research has a good theoretical value for improving the wear resistance and service life of cutting tools and is easy to be used broadly.