不锈钢表面激光熔覆镍基合金层研究

Investigation of Nickel-Based Alloys Coatings on Stainless Steel by Laser Cladding

采用多层多道搭接的激光熔覆方法在0Cr18Ni10Ti不锈钢表面上分别熔覆两种镍基合金涂层。1#合金涂层的硬度在HRC34左右,无开裂;2#合金涂层的硬度在HRC47左右,易开裂。采用硬度较低的1#合金涂层作为过渡层成功解决了2#合金涂层的开裂问题,成功制备出大面积较厚涂层。经光学显微镜(OM)、X射线衍射(XRD)、扫描电子显微镜(SEM)以及能谱(EDS)分析可知,大面积熔覆层的表层主要由γ-Ni枝晶、块状γ-Ni和M12C型碳化物增强相组成。显微硬度测试表明,表层平均硬度达HV0.2583,自熔覆层表层至基体,显微硬度逐渐降低。

Two kinds of nickel-based alloy coatings were formed on 0Cr18Ni10Ti stainless steel surface by laser cladding. The hardness of the coating formed with nickel based alloy 1 was about HRC 34, no cracks existed in the coating. While the hardness of the coating with nickel based alloy 2 was as high as HRC 47, and this coating presented high tendency to crack. Introducing a layer of softer nickel based alloy 1 as a transition one to the coatings, the problem of crack presented in the coating with nickel based alloy 2 could be resolved. And thicker coatings with large area were prepared successfully. The microstructure of the large area coatings were characterized by means of optical microscopy （OM）, X-ray diffraction （XRD）, scanning electron microscope （SEM） as well as energy-dispersive spectroscope （EDS）. The results indicated that the upper area of the coating formed with nickel based alloy 2 was composed of γ-Ni matrix dendrite, γ-Ni lumps and reinforcing phase M12C carbides. The results of micro-hardness analysis along the coating thickness showed that the average hardness of the surface layer of the coatings could reach HV0.2 583 and the hardness decreased gradually from the coating surface to the substrate.