球墨铸铁表面激光熔覆钴基合金涂层的组织与性能

发布时间：2018-07-05 06:22

本文选题：球墨铸铁 + 激光熔覆　；参考：《稀有金属》2017年12期

【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。
[Abstract]:In order to study the microstructure and properties of cobalt based alloy cladding on the surface of nodular cast iron QT600-3 by laser cladding, the CoCrW alloy powder with a particle size of 46 ~ 106 渭 m was laser cladding to the surface of QT600-3 substrate by a 6 kW CO _ 2 laser. The technological parameters of laser cladding are as follows: laser power is 3.0 kW, scanning speed is V ~ (350 mm) min ~ (-1), spot diameter is 2 mm, lap ratio is 1.5, cladding thickness is about 3 mm, the thickness of cladding layer is about 3 mm. The temperature field of the sample is controlled by heat compensation method in the process of cladding. By means of Olympus metallographic microscope (OM) and Zeiss-Sigma scanning electron microscope (SEM), the microstructure, phase and hardness of the cladding layer were analyzed by means of Xpert MPD Pro X-ray diffractometer (XRD) and MHV2000 digital display microhardness meter. The results show that the surface of the cladding is well formed, without cracks, porosity and other defects, the cladding is divided into melting zone, bonding zone and heat affected zone, and the cladding and matrix metallurgical bonding are good. It is mainly composed of 纬 -Co supersaturated solid solution and carbides, such as CoCxX Cr7CS3. The melting zone is composed of dendrites in the surface layer and cellular crystals inside, and the microstructure changes in the heat-affected zone, resulting in martensite and partial dissolution of spherical graphite. The diameters become smaller. With the increase of the surface distance between the cladding layer and the nodular cast iron substrate, the hardness of the cladding layer increases rapidly first, then slowly, and finally increases rapidly in the surface area. The highest hardness of the cladding layer reaches HV0.21077, which is more than 4 times higher than that of the nodular cast iron matrix.
【作者单位】：沈阳航空航天大学材料科学与工程学院;沈阳大陆激光成套设备有限公司;
【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
【分类号】：TG174.4

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