Microstructural evolution, mechanical properties and surface quality of TC11 titanium alloy subjected to waterjet-assisted laser direct inscription

Waterjet-assisted laser direct inscription (WJALDI) technology has presented a positive effect to alleviate the thermal damage in workpieces caused by laser ablation. This research pays attention to the effect of aqueous media on the microstructure evolution and phase composition of materials during laser ablation, and few relevant researches have been reported. In this work, titanium alloy (TC11) was applied to fabricate microgrooves utilizing WJALDI and laser direct inscription in the air (LDI). The interaction effects between the laser, water, and the material within a complete ablation cycle were analyzed in depth. The geometry and thermal damage region were observed and discussed to prove the machining performance. The microstructure evolution that happened on and underneath the microgroove surface was also studied. The results revealed that the effect of cooling and impacting significantly reduced the accumulation of debris and molten metal, and better processing quality was obtained in WJALDI. According to the analysis of electron backscattered diffraction (EBSD), the grain refinement of the inner material was alleviated, low-angle grain boundaries with the features of uniform distribution were generated, and the adjacent grains of α phase have small kernel average misorientation. In addition, compared with LDI, WJALDI offered a wide microgroove with a small size of heat affected zone (HAZ) and thin thickness of the recast layer, while less depth. Therefore, the developed technology in this work could be a promising approach for the micromachining of titanium alloy or even other difficult-to-cut materials with high quality.