柱塞激光熔覆镍基合金工艺与组织结构分析

Technology and Microstructural Analyses of Laser Cladding Nickel base Alloy on Plugs

本工作针对高压匀质机柱塞应用背景，在奥氏体不锈钢为基材的柱塞上激光熔覆镍基硬面合金，对其工艺、微观组织结构和性能进行了较深入的分析研究．通过扫描电镜、Ｘ光衍射、金相等微观分析方法，对快速凝固激光熔覆合金层的非平衡态微观组织特性与其性能关系进行研究．结果表明：在激光熔覆柱塞表面获得了镍基硬面合金层与不锈钢基材的优良冶金结合；合金层微观组织为超细的共晶组织，在含Ｃｒ、Ｓｉ、Ｃ、Ｂ元素的过饱和γＮｉ（Ｆｅ）奥氏体基体中，均匀分布着细密的树枝状碳化物、硼化物及硅化物；这是它具有良好的力学性能和耐磨耐蚀使用性能的关键．

In the light of the application on the plugs of high pressure homogenizer, the technology, microstructural analyses and properties for laser cladding nickel base hardfacing alloy on stainless steel matrix have been studied deeply. These relationships of microstructure and properties of laser cladding which have characteristics of rapid solidification with non equilibrium state have been investigated by using OM, SEM, EDAX, XRD and microhardeness tester. The results show that there exists an optimum metallurgical bond and very fine microstructures which comprise ultra fine and homogeneous dendrites eutectic of carbide, boride and silicate in oversaturated γNi(Fe) matrix. These are keys which possess high mechanical properties and good resistance to wear and corrosion. Microstructure and properties of plug by spray coating have also been analysed and compared.