A comprehensive experimental study on surface integrity by end milling Ti―6Al―4V

Abstract End milling titanium Ti–6Al–4V has wide applications in aerospace, biomedical, and chemical industries. However, milling induced surface integrity has received little attention. In this study, a series of end milling experiments were conducted to comprehensively characterize surface integrity at various milling conditions. The experimental results have shown that the milled surface shows the anisotropic nature with the range of surface roughness values from 0.6 to 1.0 μm. Surface roughness value increases with feed and radial depth-of-cut (DoC), but has much less variation in the cutting speed range. Compressive residual normal stress occurs in both cutting and feed directions, while the influences of cutting speed and feed on residual stress trend are quite different. The microstructure analysis shows that β phase becomes much smaller and severely deformed in the near surface with the cutting speed, but phase transformation was absent for the milling conditions. The milled surface microhardness is about 70–90% higher than the bulk material in the subsurface.

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