光纤激光氮化处理对TC4合金组织和性能的影响

Effect of laser power on microstructure and properties of laser nitriding layer of TC4 alloy

采用高功率光纤激光器在氮气气氛中对TC4钛合金表面进行氮化,制备出渗氮层,并研究了光纤激光功率对TC4钛合金氮化层表面形貌、组织结构以及显微硬度的影响.结果表明:氮化层表面呈现粗糙和光滑两种形貌,氮化层组织为枝晶状组织,热影响区组织为针状组织,当扫描速度为10 mm/s、氮气流量10 L/min、喷嘴距离为3 mm、离焦量为0 mm时,渗氮层的熔深、熔宽均随着激光功率增大而呈现出增大趋势.此外,在距离氮化层表面相同深度的显微硬度随着激光功率增大也呈现出增大趋势.

The nitrided layer of TC4 titanium alloy was prepared by using IPG high-power fiber laser in nitrogen atmosphere in this study.Effects of optical fiber laser power on surface morphology,microstructure and microhardness of the TC4 titanium alloy nitrided layer were investigated.Obtained results have demonstrated that the surface of the nitrided layer takes rough and smooth of two types.The microstructure of nitrided layer is dendritic,and that of HAZ is needle-like.When scanning speed takes 10 mm/s,the nitrogen flow rate is 10 L/min,the distance of the nozzle is 3 mm and the defocus reaches 0 mm,the penetration depth and width of the nitrided layer increase with the increase of laser power.In addition,the microhardness at the same depth from the surface of the nitrided layer increases with the increase of laser power.