Microstructural damage during high-speed milling of titanium alloys

The majority of aero-structural titanium alloys are high-speed milled. This paper identifies microstructural subsurface damage in the form of intense slip bands after high-speed milling of Ti–6Al–4V and Ti-834. Such microstructural features are undetected by current surface integrity techniques. The alignment and density of the intense slip bands were found to be dependent on the subsurface alpha grain orientation. Such microstructural subsurface damage could degrade in-service properties, due to a reduction in fatigue crack initiation resistance.