工艺参数对球墨铸铁表面激光熔覆(TiC+B4C)/Co基合金涂层组织和性能的影响

The effects of laser cladding parameters on the microstructure and properties of cladding layer of(TiC+B4C)/Co-based alloy on the surface of ductile iron

采用激光熔覆的方法在QT600-3表面熔覆含量为50wt.%(TiC+B 4C)的Co基合金粉末,研究工艺参数对熔覆层显微组织、第二相和熔覆层硬度的影响规律。结果表明当扫描速度一定时,随着激光功率增大,枝晶臂间距先增加后减小,TiC和团聚状B 4C颗粒尺寸均减小,且分布更加均匀,而TiC的形貌由不规则块状逐渐向花瓣状为主变化;当激光功率一定时,扫描速度增大,枝晶臂间距均减小,团聚B 4C和TiC平均尺寸增大,且分布趋于不均匀,熔化后析出的TiC减少,TiC的形貌则由花瓣状向不规则多边形为主变化;当激光功率P=1.2 kW、扫描速度V=4 mm/s时,熔覆层平均硬度最大,为1379.28 HV 0.2,是基体硬度的5.9倍。

The cladding layer of Co-based alloy with 50wt.%(TiC+B 4C)is prepared on the surface of QT600-3 ductile iron by the laser cladding method and the effects of the optical fibre laser parameters on the microstructure,the second phases and hardness of the cladding layer are investigated.The results show that the dendrite arm space increases and then decreases with the increase of laser power at a given scanning speed of laser.With increasing laser power,the particle sizes of both TiC and clustered B 4C decrease with uniform distribution.The TiC morphology changes from irregular block to petaloid shape.At a given laser power,the dendrite arm space decreases,but the average sizes of the clustered B 4C and TiC particles increases with the increase of the laser scanning speed,with an uneven distribution.The petaloid morphology of TiC is transformed into irregular polygon shape.The maximal average hardness of laser cladding layer reached to 1379.28 HV 0.2,5.9-fold of that of ductile iron matrix,when the laser power is 1.2 kW and the scanning speed of laser 4mm/s.