激光熔覆Stellite6涂层工艺优化及组织性能研究

Process Optimization,Microstructure and Properties of Laser-Cladded Stellite6 Coatings

采用激光同轴送粉技术制备Stellite6钴基熔覆层,通过正交试验、单层单道、单层多道和多层多道工艺试验优化激光熔覆工艺参数。利用扫描电子显微镜、光学显微镜、X射线衍射仪表征了熔覆层显微组织结构,同时分析了微观硬度和耐摩擦磨损性能。结果表明,以熔覆层稀释率、成形系数和显微硬度为优化目标参数,可有效筛选激光熔覆Stellite6涂层制备工艺。所制备Stellite6涂层组织均匀,熔合线附近为平面晶,涂层中部区域为树枝晶,顶部区域为等轴晶。熔覆层物相由fcc-Co、(Co,W)_(3)C与Cr_(23)C_(6)等组成,平均硬度为457 HV。熔覆层耐摩擦磨损性能优于316L不锈钢基体,其主要磨损机制为磨粒磨损。

Stellite6 Co-based coatings were prepared through the coaxial powder-feeding laser cladding technique.The laser cladding parameters were optimized by means of the combination of orthogonal test design,single pass cladding,single-layer multi-pass cladding and multi-layer multi-pass cladding.The microstructure of the cladded coatings was characterized through scanning electron microscope,optical microscope,X-ray diffractometer,while the microhardness and the tribological performance of the coatings were also investigated.Results show that the optimal laser cladding parameters were successfully obtained through comprehensively analyzing the dilution rate,forming coefficient and microhardness of the coating.Furthermore,homogeneous microstructure was developed inside the cladded coating,which was consisted of plane crystals near the fusion zone,dendrites in the central region and equiaxed grains in the top region.The laser-cladded Stellite6 coating was composed of fcc-Co,(Co,W)_(3) and Cr_(23)C_(6)phases,and its average microhardness reached 457 HV.The wear-resistant property of the laser-cladded Stellite6 coating was found superior compared to the 316L base metal and the wear behavior of the coating was featured of abrasive wear.