Influence of high pressure water jet-assisted machining on surface residual stresses on the work-piece of Ti-6AL-4V alloy

Titanium alloys are used in aerospace industry owing to their high strength to weight ratio. These alloys are considered to be difficult to machine due to their rigidity and poor thermal conductivity. High-pressure jet-assisted machining of titanium alloys is beneficial. It not only increases production efficiency, by increasing the cutting speed and lowering temperature both in cutting zone and the cutting tool, but also improves chip control and increases tool life. It also produces better surface integrity and compress residual stress, which improves the properties of work-piece. Ti-6Al-4V (Ti-64) rod was machined by turning in two different manners, finishing and roughing. Tests were conducted on a lathe using the same cutting data and different cooling systems, high pressure and conventional. In order to illustrate the effect of high-pressure jet-assisted machining on the properties of the work-piece of Ti-6Al-4V and its residual stress, x-ray defractometery was used. The present study revealed that there were compressive residual stresses in the transversal and longitudinal directions of the cut and the residual stresses in both directions were nearly of the same magnitude. The depth profile of residual stress was measured as well after removing the material by etching. The shear stress was very low, almost negligible. High pressure cooling affected residual stresses in finishing more than in roughing