不锈钢表面多道激光熔覆Ni基涂层的组织与性能  

Microstructures and properties of multiple-pass laser cladding Ni-based coatings on stainless steel surface

作　　者：刘洪喜[1] 曾维华[1] 张晓伟[1] 王传琦[1] 蒋业华[1] 

机构地区：[1]昆明理工大学材料科学与工程学院,云南昆明650093

出　　处：《光学精密工程》2011年第7期1515-1523,共9页Optics and Precision Engineering

基　　金：国家自然科学基金资助项目(No.50671045);云南省自然科学基金资助项目(No.2008ZC021M);昆明理工大学分析测试基金资助项目(2009-022)

摘　　要：为提高不锈钢的硬度和耐蚀性能,利用6 kW横流CO2激光器在1Cr18Ni9Ti表面进行了单道和多道Ni25WC35合金粉末熔覆。X射线能量色散分析(EDAX)和X射线衍射(XRD)分析表明,熔覆层主要由(Fe,Ni)固溶体和WC原位自生成的W2C组成,同时含有CrNiFeC,Cu3.8Ni化合物和Fe W3C,Ni2Si,Fe3Ni3B等硬质相。光学显微形貌观察显示熔覆层组织均匀、致密,与基体结合良好。显微硬度测试得出熔覆层硬度为基体的2倍,最高出现在双道试样第二道熔覆层CZ区中部,其值达到650 HV。熔覆层在5.0%NaCl饱和溶液中的最高自腐蚀电位为-488.70 mV,较基体上升了630.9 mV;最低腐蚀电流密度为0.55μA·cm-2,较基体降低了75.11%。综合比较显示单道试样耐腐蚀性能最好。In order to improve the surface hardness and corrosion resistance of stainless steel,single-pass and multi-pass lap laser cladding coatings of Ni25WC35 alloy powders were fabricated on a 1Cr18Ni9Ti substrate by a 6 kW transverse-flow CO2 laser.The coatings were examined and tested for chemical compositions,microstructure features,phase structures,microhardness,corrosion behaviors and metallographies by the X-ray Diffraction（XRD）,Scanning Electronic Microscopy（SEM）,X-ray Energy Dispersive Analysis（EDAX）,microhardness tester,electrochemistry workstation and optical microscopy（OM）,respectively.The results show that some new harden phases are formed in the coating which consists of（Fe,Ni） solid solution and some compounds such as WC,W2C,CrNiFeC,FeW3C,Ni2Si,Fe3Ni3B,and these harden phases improve the hardness and corrosion resistance of the substrate effectively.OM observation displays that the microstructure of clad coating is homogeneous,compactness and forms a good metallurgical bonding layer with the substrate.Micro-hardness measurement exhibits that the surface hardness of treated sample is twice as large as that of substrate,and the highest hardness lies in the second pass cladding zone center of a double-pass coating sample and reaches 650HV.The electrochemical corrosion test in 5.0% NaCl saturated solution indicates that the maximum self-corrosion potential（Ecorr） of clad coating sample changes from 630.90 mV to positive direction,and the lowest corrosion current density（Icorr） changes from 2.21 μA·cm-2 to 0.55 μA·cm-2 and decreases by 75.11%.Compared with the substrate,the corrosion resistance of laser cladding sample has been improved significantly,and the single pass cladding sample shows the best corrosion behavior.

关 键 词：激光熔覆 多道涂层 不锈钢 显微硬度 腐蚀性能 

分 类 号：TG156.99[金属学及工艺—热处理]