Subsurface deformation during precision turning of a near-alpha titanium alloy

Precision turning is an energy-intensive, yet important machining operation for critical aero-structural titanium alloy parts. High-resolution electron backscatter diffraction reveals an increase in induced subsurface deformation with increasing surface speed, contradicting observations when applying standard surface integrity techniques. Subsurface microstructural damage, such as mechanical twins and intense slip bands, provides nucleation sites for silicide precipitation during thermal exposure at 750 °C, indicating that creep and fatigue strength could be locally reduced at the machined surface.