A Multiscale Study on Machining Induced Surface Integrity in Ti-6Al-4V Alloy

Abstract

This study adopted a multiscale surface integrity approach (macro, micro, and sub-micro scale) to study the effects of cutting conditions and varying cutting fluid applications on the final surface state in Ti-6Al-4V alloy. Surface integrity parameters that were studied in this work are surface roughness, subsurface microhardness, residual stresses, and microstructural alterations. The results show that there is some correlation between microstructural and mechanical characteristics of machining-induced surface integrity. Also, different residual stress profiles were obtained for TMQF (Targeted Minimum Quantity Fluid) machining (compressive residual stress profile) and flood machining (tensile residual stress profile), which underlines the importance of selecting the right cutting fluid application. This work could aid in choosing the right cutting fluid application for the finish machining operation of Ti-6Al-4V alloy to obtain a desired final superior surface integrity. TMQF application conditions produced better surface integrity metrics (lower surface roughness, compressive surface residual stresses, and no undesirable microstructural damage) compared to flood fluid application while finish machining of Ti-6Al-4V titanium alloy.