TC4钛合金表面激光气体氮化研究

Study on Laser Nitriding of TC4 Titanium Alloy Surface

采用光纤激光对TC4钛合金板进行氮化试验,研究氮化层的成型、显微组织和显微硬度。测量了氮化层宽度和深度,拍摄了氮化层表面三维轮廓,拍摄了氮化层横截面显微照片,测量了氮化层显微硬度。实验表明,采用合适的工艺参数进行氮化,氮化层表面呈现TiN特有的金黄色。随激光功率增大,氮化层表面会发生氧化,并且氮化层宽度和深度会增加,深度增加更快一些。氮化层表面的中心光滑、两侧粗糙。氮化层表面形成3~5μm连续TiN层,内部显微组织为粗大的树枝晶,并且有明显的二次和三次枝晶。氮化层显微硬度随深度增大而减小,采用较大激光功率时,氮化层硬度更高。本研究中得到最大氮化层硬度为981 HV,氮化层厚度约800~900μm。

TC4 titanium alloy plate was nitrided by fiber laser. The forming, microstructure and microhardness of the nitriding layer was studied. The width and depth of the nitriding layer were measured, and the three-dimensional contour of the nitriding layer was taken. The cross section photomicrograph of the nitriding layer was taken and the hardness of the nitriding layer was measured. Experimental results show, the surface of the nitriding layer shows the characteristic golden color of Ti N with proper process parameters. With the increase of laser power, the surface of the nitriding layer oxidizes, and the width and depth of the nitriding layer increase, the depth increases faster. The surface of the nitriding layer shows the characteristics of smooth center and rough sides. 3-5 μm continuous Ti N layers are formed on the surface of the nitriding layer, and the microstructure of the nitriding thick presents large dendritic, with obvious secondary and tertiary dendrites. The hardness of the nitriding layer decreases with the increase of depth, the hardness of the nitriding layer is higher when the laser power is higher.In this study, the maximum hardness of the nitriding layer is 981 HV, the thickness of the nitriding layer is about 800-900 μm.