Abstract: Although titanium alloy is widely used in aerospace and nuclear power fields due to its superior thermomechanical properties (high temperature resistance and corrosion resistance), its unique low thermal conductivity, high strength and work hardening properties make it difficult to process and maintain surface integrity. Laser-assisted processing methods can effectively improve the cutting performance of difficult-to-cut materials and improve their surface integrity. Therefore, this paper proposes a special processing method (laser belt processing method) that combines laser processing and belt grinding, and establishes a focus control movement model for laser belt processing by using laser heating characteristics and sanding to control the focus. With the flexible characteristics of grinding, the material can be quickly removed. The processing experiment is carried out on the self-built laser abrasive belt processing experimental platform. The surface three-dimensional morphology and microstructure of the titanium alloy samples processed by the laser abrasive belt under different defocusing amounts are analyzed and compared. The results show that the amount of defocus during the laser abrasive belt processing greatly affects energy distribution of the laser, leading to changes in the laser abrasive belt processing mechanism; the reduction in the amount of defocus causes the surface roughness S_a to first decrease from 8.07 μm to 7.40 μm, then increases to 22.1 μm; the phenomenon of material gasification and melting removal becomes more obvious. Finally, it is proved that the laser abrasive belt processing method can improve the processing performance of titanium alloy, and can improve the wear resistance of the surface, which has broad application prospects.

Key words: titanium alloy, laser belt grinding, defocus control, surface topography, thermomechanical properties