球墨铸铁表面激光熔覆钴基合金涂层的组织与性能  

Microstructure and Property of Laser Cladding Cobalt Based Alloy Coatings on Ductile Cast Iron

作　　者：童文辉 赵子龙 王杰 国旭明 段新华[2] 刘豫[2] Tong Wenhui;Zhao Zilong;Wang Jie;Guo Xuming;Duan Xinhua;Liu Yu(Shenyang Aerospace University School of Materials Science and Engineering, Shenyang 110136, China;Shenyang Dalu Laser Complete Equipment Co., Ltd, Shenyang 110136, China)

机构地区：[1]沈阳航空航天大学材料科学与工程学院,辽宁沈阳110136 [2]沈阳大陆激光成套设备有限公司,辽宁沈阳110136

出　　处：《稀有金属》2017年第12期1386-1390,共5页Chinese Journal of Rare Metals

基　　金：辽宁省教育厅科学研究项目(L201705);沈阳市产业发展应用基础研究计划项目(17-231-1-25)资助

摘　　要：为了研究球墨铸铁QT600-3表面激光熔覆钴基合金的组织和性能,本试验采用预置送粉法,利用6 kW CO_2激光器将粒度为46~106μm的CoCrW合金粉末激光熔覆到QT600-3基材表面,激光熔覆工艺参数为:激光功率P=3.0 kW、扫描速度V=350 mm·min^(-1)、光斑直径2 mm、搭接率1.5,三道次熔覆,熔覆层厚度约为3 mm,在熔覆过程中采用热量补偿方法对试样温度场进行调控。通过Olympus金相显微镜(OM)、Zeiss-Sigma扫描电镜(SEM)、X'Pert MPD Pro型X射线衍射仪(XRD)、MHV2000数显显微硬度计,分析了熔覆层横截面的显微组织、物相及硬度的变化规律。结果表明:熔覆层表面成形良好,无裂纹、气孔等缺陷;熔覆层分为熔化区、结合区和热影响区,熔覆层与基体冶金结合良好,主要由γ-Co(面心立方)过饱和固溶体以及碳化物CoC_x,Cr_7C_3等组成;熔化区由表层的树枝晶和内部的胞状晶组成,在热影响区发生了组织转变,形成了马氏体并且球状石墨部分溶解,直径变小。熔覆层硬度随着与球墨铸铁基体表面距离增加,呈现先快速增大,后平缓增加,最后在表层区域又快速增大,熔覆层的最高硬度达到HV0.21077,较球墨铸铁基体的硬度提高了4倍以上。In order to study the microstructure and property of cobalt based alloy layer cladding on the surface of ductile cast iron QT600-3 by laser, laser cladding of CoCrW alloy powder with the particle size of 46 - 106 μm on the surface of QT600-3 was performed by 6 kW CO2 laser. Laser cladding process parameters were ： laser power P = 3.0 kW, scanning speed V = 350 mm·min - 1 , laser spot diameter 2 mm, lap ratio 1.5, three pass cladding, for which the thickness of cladding layer was about 3 mm. The temperature distri- bution of the cast iron sample was adjusted and controlled by the heat compensation during laser cladding processing. The microstructure, composition, phases and hardness on the cross section of the cladding layer were investigated by Olympus metallurgical microscope （OM） , Zeiss-Sigma scanning electron microscope （SEM） , X＇Pert MPD Pro X-ray diffraction （XRD） and M HV2000 digital micro hardness tester and the hardness changing was analyzed. The results showed that, the surface quality of the cladding layer was fine without crack, porosity and other defects; the cladding layer could be divided into melting zone, combined zone and heat affected zone, and it was integrated metallurgically with the ductile cast iron matrix, which was mainly composed of 3＇-Co （ face centered cubic ） solid solution and carbide of CoCx, Cr7C3 , etc. The melting zone consisted of a surface layer of dendritic crystals and an internal layer of cellular crystals, and the transformation to the plate martensite occurred in the heat affected zone, where the globular graphite partially dissolved to the smaller graphite. The hardness of the cross section of the cladding layer increased rapidly and then increased gently with the increase of the distance from the surface of the graphite cast iron matrix, finally in the surface area rapidly increased. The maximum hardness of the cladding layer was HV0.2 1077, which was up to 4 times higher than that of the substrate of ductile cast iron.

关 键 词：球墨铸铁 激光熔覆 钴基合金 显微组织 硬度 

分 类 号：TG456.7[金属学及工艺—焊接]