Influence of finish milling parameters on machined surface integrity and fatigue behavior of Ti1023 workpiece

Ti1023 is a high specific strength material, widely used for manufacturing load-bearing workpieces in aerospace, aviation, and other fields, of which the main failure mode is fatigue fracture. Milling is the main process of Ti1023 complex structure parts, and the surface integrity generated has a significant impact on the fatigue life. Based on the deep mechanism analysis on the surface topography and surface roughness formation, the influence of the finish milling parameters on the machined surface integrity and the fatigue life of specimens is obtained. By conducting the milling experiments, the influence of surface roughness, surface microhardness, and surface residual stress on the fatigue life of specimens is analyzed. Results show that milling speed vs is the predominating parameter affecting the fatigue performance of Ti1023 irrespective of the tool wear; the essential reason of which is the surface enhancement caused by surface microhardening rate and the thickness of microstructural deforming layer underneath the machined surface. Although the feed per tooth f(z) obviously influences the surface roughness, it has little effect on the surface stress concentration factor. Therefore, fz is not decisive to the fatigue performance of the specimen. The research results provide guidelines on the optimization of finish milling parameters of Ti1023, as well as a theoretical basis for the anti-fatigue investigation of Ti1023 parts.