激光熔覆制备Stellite6涂层的组织与性能

基于激光熔覆同轴送粉技术,在2Cr13不锈钢表面制备了Stellite6合金涂层,研究了工艺参数对涂层宏观形貌的影响,分析了涂层的显微组织和显微硬度。研究结果表明:在激光功率为2.5 kW,扫描速度为5 mm/s,送粉速率为13.2 g/min,搭接率为38 %时,可获得平整无缺陷的Stellite6涂层。熔覆层可分为一次熔化区、道间重熔区和层间重熔区。熔覆层的组织主要由胞状晶和树枝晶构成；相比于一次熔化区,道间重熔区和层间重熔区的组织较为粗大。通过合理调整道间停留时间和层间停留时间,可使熔覆层周期性循环组织中的一次熔化区的组织占比从54.9 %提升至73.1 %,从而提升熔覆层的整体硬度。

Microstructure and properties of Stellite6 coating prepared by laser cladding

Based on the technology of laser cladding using coaxial powder feeding,the Stellite6 alloy coating was coated on the surface of 2Cr13 stainless steel.The effects of processing parameters on the macroscopic morphology of the coating were studied,the microstructure and microhardness of the coating were analyzed.The results showed that the flat and defect-free Stellite6 coating could be obtained at the laser power,the scanning speed,the powder feeding rate and the lap ratio of 2.5 kW,5 mm/s,13.2 g/min,and 38 %,respectively.The structure section of the cladding layer included three zones:primary melting zones,inter-channel remelting zones,and inter-layer remelting zones.The microstructures of the cladding layer were composed of cell and dendrites crystals.Compared with the primary melting zone,the microstructures of inter-channel remelting zone and the inter-layer remelting zone were coarse.By reasonably adjusting the residence time of the channels and layers,the proportion of the microstructure of the primary melting zone in the periodic cyclic structure of the cladding layer were increased from 54.9 % to 73.1 %,resulting in the improvement of the overall hardness of the cladding layer.