激光熔覆多层熔覆层组织与性能研究

Microstructure and Properties of Multi-layer Coating by Laser Cladding

采用高功率半导体激光器在45#钢圆棒表面制备了Ni25、Co2和316L多层熔覆层,用扫描电镜(SEM)、X射线衍射仪(XRD)对熔覆层的微观组织及物相进行表征,并测试涂层试样的硬度与耐磨性能。结果表明,熔覆层组织均匀、致密,晶粒细小,与基体成冶金结合;激光多层熔覆时,熔覆层经多层重叠扫描,重复融化凝固造成层与层结合区存在一明显白亮带,层内组织在该处存在明显分层现象;Ni25合金熔覆层主要物相有γ-Ni固溶体、BNi3、B2Fe3Ni3、C-Fe-Si等;Co2熔覆层主要由γ-Co、γ-Ni固溶体等组成;多层熔覆层硬度和耐磨性相较于基体,有较大提高,Co2合金熔覆层平均硬度值最高,达到了584.7HV0.3,多层熔覆层经过多次重叠扫描,重复融化凝固熔覆层硬度更加均匀。

Ni25,Co2 and 316L multi-layer coatings were prepared on 45 steel round bar by using a high power diode laser. The morphology of laser cladding layer was observed by scanning electronic microscope（SEM）, and the phase transformation was characterized by X-ray diffraction（XRD）, and the hardness and wear resistance of the coating were tested. The results show that the coating is uniform and compact, with fine grain size and metallurgical bonding with the substrate; The cladding layer has a clear white bright band in the layer and layer, and there are obvious faults in the layers which caused by overlap scanning; The main structure of Ni25 coating is γ-Ni.BNis .B2 Fes Nis .C-Fe-Si and the main structure of Co2 coating is γ-Co,γ-Ni; The hardness and wear resistance of the multi-layer coatings are greatly improved compared with the substrate, the average hard- ness of Co2 coating is the highest, which is reached 584.7HV0.3, the hardness of the cladding layer is much more uniform after repeated melting and solidification.