激光熔覆Mo_2C-Co基合金的工艺参数对其组织的影响

Influence of processing parameters of laser clad Mo_2C-Co-based alloy on its microstructure

利用10kW的CO2激光器在409L铁素体不锈钢表面激光熔覆w(Mo2C)=20%的Mo2C/Co基涂层,运用SEM、EDS、XRD及显微硬度仪观察和分析激光功率和扫描速度对熔覆层成型性、尺寸、组织及性能的影响.结果表明:激光熔覆合理的工艺参数为:P=3.6kW,v=8mm/s;钴基熔覆层组织由平面晶、柱状晶、树枝晶构成,熔覆层中物相主要为Mo2C颗粒、亚共晶γ-Co和共晶碳化物Cr23C6、Cr7C3;由于Mo2C颗粒加入,凝固组织的晶粒尺寸减小、晶粒细化,涂层的显微硬度从870HV提高至1 400HV.

Laser melt-clad Mo2C/Co-based alloy coating with w（Mo2C）=20% was fabricated on the surface of 409L ferritic stainless steel by using 10 kW CO2 laser.The process of laser cladding with different processing parameters such as laser power and scanning speed was studied,and on the basis of it,the formability,dimensions,organization,and performance of melt-clad layer were observed and analyzed with SEM,EDS,XRD and microscopic hardness meter.The result indicated that the rational laser cladding parameters were as follows： P=3.6 kW,v=8 mm/s,the microstructure of the coating was composed of planar,columnar crystals,and the dendrite,and the cladding coating was mainly composed of Mo2C particles,sub-eutectic γ-Co and eutectic carbides of Cr23C6 and Cr7C3.With Mo2C added into Co-based alloy,the size of solidification microstructure was decreased,the gains were refined,and microhardness of the coating was improved from 870 HV to 1 400 HV.