Correlation of surface integrity with processing parameters and advanced interface cooling/lubrication in burnishing of Ti-6Al-4V alloy

Burnishing (also known as deep rolling) is a chipless finishing process used to improve the surface integrity of metals by severe plastic deformation (SPD) of surface asperities. As surface integrity has a large impact upon the functional performance of aerospace components and assemblies, burnishing is a means of significantly increasing the cyclical fatigue life of critical components, such as turbine and compressor airfoils. The objective of this study was to evaluate the process- induced surface integrity of Ti-6Al-4V alloy as a function of number of overlapping passes, loading force, as well as feed and speed, for four cooling/lubrication conditions: conventional flood cooling (emulsion), minimum quantity lubrication (MQL), cryogenic cooling (LN2) and hybrid cooling/lubrication (MQL+LN2). Analysis revealed that all examined burnishing parameters, with the exception of speed, play a fundamental role in controlling the processed surface integrity and thus also in the likely functional performance of Ti-6Al-4V aerospace components.