1 Key Laboratory of Electromagnetic Processing of Materials, Northeastern University, Shenyang 110819, China 2 Petrochina Daqing Petrochemical Company Oil Refinery, Daqing 163714, China
Cite this article:
Xudong SUI,Guojian LI,Qiang WANG,Xuesi QIN,Xiangkui ZHOU,Kai WANG,Lijian ZUO. PREPARATION OF Ti1-xAlxN COATING IN CUTTING TITANIUM ALLOY AND ITS CUTTING PERFORMANCE. Acta Metall Sin, 2016, 52(6): 741-746.
High-strength lightweight titanium alloy structural materials have been widely used in aerospace and other industry. However, the titanium is hard to machine due to its characteristics of low thermal conductivity, high chemical affinity and low elastic modulus. Coating tools provide a solution to overcome the problem of cutting titanium alloy. Ti1-xAlxN coating is one of the most popular candidates in cutting titanium alloy. However, the cutting performance and wear mechanism of the sputtering Ti1-xAlxN coating should be studied further in order to meet the demands of cutting titanium alloy. In this work, Ti1-xAlxN coatings with different Al contents have been prepared by magnetron sputtering. Microstructure and mechanical properties of the coatings were examined by XRD, SEM, EDX and nanoindenter. Results show that the coatings is a single fcc structure with a (111) preferred orientation when x is in the range of 0.50~0.58 (atomic fraction). When the Al content is 0.63, the hexagonal AlN is formed in the coating and the hardness declines. In addition, the surface particle size of Ti1-xAlxN coatings increases and the coating density decreases with increasing the Al content. The results of titanium cutting experiment indicate that the tool wear is mainly adhesive wear and chipping. The cutting performances of Ti0.50Al0.50N coated tool is slightly better than uncoated tool and are much better than those of Ti0.42Al0.58 and Ti0.37Al0.63N coated tools at a lower cutting speed (65 m/min). The cutting performance of Ti0.50Al0.50N coated tool is the best at a higher cutting speed of 100 m/min and is four times larger than that of uncoated tool. The excellent cutting performance of Ti0.50Al0.50N coating is mainly due to its high surface density and high hardness, which lead to the formation of regular and dense built-up edge during titanium cutting. Therefore, Ti0.50Al0.50N coating with a (111) preferred orientation, dense surface and relatively low Al content is recommended in high speed turning titanium.
Fig.1 XRD patterns of Ti1-xAlxN coatings with different Al contents
Fig.2 SEM images of surface of Ti0.50Al0.50N (a), Ti0.42Al0.58N (b) and Ti0.37Al0.63N (c) coatings
Fig.3 Hardness and elastic modulus of Ti0.50Al0.50N, Ti0.42Al0.58N and Ti0.37Al0.63N coatings
Fig.4 Tool flank wear (Vb) and morphologies (insets) of the uncoated and coated tools with different Al contents after TC4 turned at 65 m/min (a) and 100 m/min (b)
Fig.5 SEM images of the uncoated tool and coated tools with different Al contents after TC4 turned at 65 m/min
