激光工艺参数对NiCoCrAlYSi熔覆层微观组织及性能的影响

采用激光熔覆技术在Ni625高温合金表面制备NiCoCrAlYSi涂层，研究激光功率和扫描速度对NiCoCrAlYSi熔覆层冶金质量及微观组织的影响。通过测试熔覆层显微硬度及摩擦磨损性能，建立激光熔覆工艺参数、微观组织与熔覆层性能之间的关系。结果表明：随着激光输入能量从36 J/mm²升高至73.3 J/mm²，熔覆层厚度从534 μm增加到1 535 μm，表面气孔率从0.07%增大到0.65%，以及平均气孔尺寸从0.23 μm增大到1.33 μm，且熔覆层微观组织发生粗化，熔覆层表面气孔率的增大及组织粗化导致其显微硬度和耐磨性逐渐降低；当激光输入能量比为36 J/mm²时，熔覆层组织致密性最高、晶粒尺寸最细小，且内部分布有大量的位错及位错墙结构，此时熔覆层硬度及耐磨性也最佳。

Effect of Laser Process Parameters on Microstructures and Properties of NiCoCrAlYSi Laser Cladding Coating

NiCoCrAlYSi coating was fabricated on Ni625 superalloy by laser cladding technique, and the influences of laser power and scanning speed on the metallurgical quality and microstructure of NiCoCrAlYSi cladding coating were researched. The relationship among the laser cladding process parameters, and the microstructures and properties of cladding coating was analyzed by testing its micro-hardness, and friction and wear properties. The results show that, with the increase in laser input energy from 36 J/mm² to 73.3 J/mm², the thickness of cladding layer increases from 534 μm to 1 535 μm, the surface porosity increases from 0.07% to 0.65%, and the pore size increases from 0.23 μm to 1.33 μm. In addition, the grain size of cladding layer increases. The microhardness and wear resistance of the cladding layer decrease gradually with the increase in porosity and grain size. When the laser input energy ratio is 36 J/mm², a cladding coating with high compactness, supper refined grains and high density of dislocations is obtained, which has optimal microhardness and wear resistance.