Simulation on dynamic characteristics of TC4 cutting with crack defects

Titanium alloys play an important role in aerospace and other fields. However, after precision forging and cold rolling process, some defects will appear on the subsurface of titanium alloy bars, thus reducing the surface quality and precision of turning process. This study aimed at exploring the effect of crack defects on TC4 cutting. Firstly, the finite element cutting simulation model of TC4 material with crack defects was established in ABAQUS. Then, the cutting parameters such as cutting force, stress concentration, chip morphology, residual stress were obtained by changing the variables such as the size and height of crack defects. Finally, the turning experiment was carried out on centerless lathe. The results show that the cutting force changes abruptly when the defect position is located on the cutting path, the maximal stress occurs at the tip of the defect, and the mutation of stress value is more serious with the increase of defect size; the buckling deformation of chip morphology occurs and becomes less serious with the increase of the distance between the defect position and the workpiece surface; the surface residual stress near the defect is related to the stress when the tool is close to the defect, the larger defect size and the closer to the machined surface, the greater the residual stress. Therefore, under certain processing conditions, the TC4 material should avoid large size defects or increase the distance between defects and the machined surface, so as to obtain better and stable surface quality.