论文部分内容阅读
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6k W CO2激光器将粒度为150~320目的 Co Cr W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=3.0k W、扫描速度V=350mm/min、光斑直径2mm、搭接率1.5,三道次熔覆,熔覆层厚度约为3mm,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、Zeiss-Sigma扫描电镜、X′Pert MPD Pro型X射线衍射仪、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Co Cx、Cr7C3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1077HV0.2,较球墨铸铁基体的硬度提高了4倍以上。
In order to study the microstructure and properties of laser cladding Co-based alloy on ductile iron QT600-3 surface, CoWW alloy powder with particle size of 150 ~ 320 mesh was laser cladding to QT600 -3 substrate surface, laser cladding process parameters: laser power P = 3.0k W, scanning speed V = 350mm / min, spot diameter 2mm, lap rate 1.5, three pass cladding, cladding thickness of about 3mm, in the cladding process using heat compensation method to regulate the temperature field of the sample. The microstructure, phase and hardness of the cross-section of cladding layer were analyzed by Olympus microscope, Zeiss-Sigma scanning electron microscope, X’Pert MPD Pro X-ray diffractometer and MHV2000 digital microhardness tester . The results show that the surface of the cladding layer is well formed and has no defects such as cracks and pores. The cladding layer is divided into the melting zone, the binding zone and the heat affected zone. The cladding layer and the base metallurgy are well bonded and mainly composed of γ-Co ) Supersaturated solid solution and carbides such as Co Cx, Cr7C3 and so on. The melting zone consists of dendrite in the surface layer and intragranular crystal, and the microstructure changes in the HAZ to form martensite and the spherical graphite partially dissolves. small. The hardness of cladding layer increased rapidly with the increase of the distance from the surface of ductile iron base, then increased rapidly and then increased gently. Finally, the hardness of cladding layer rapidly increased to 1077HV0.2, which was higher than the hardness of ductile iron matrix Increased by more than 4 times.