The effect of cutting speed and heat treatment on the fatigue life of Grade 5 and Grade 23 Ti–6Al–4V alloys

High speed machining is a necessary manufacturing method for ensuring productivity and profitability. However, research has demonstrated that the high speed machining process impairs the surface characteristics of materials such as Ti–6Al–4V including surface roughness and subsurface microstructural damage. Therefore, there is concern that high speed machining detrimentally influences the fatigue properties of Ti–6Al–4V components. This paper investigates the effect of cutting speed on the surface integrity and fatigue properties of Ti–6Al–4V (ASTM Grade 5) and Ti–6Al–4V ELI (ASTM Grade 23) alloys in the beta annealed and mill annealed heat treated conditions. It was found that the surface roughness and fatigue properties are not significantly influenced by cutting speed, however, the microstructure substantially influences the properties.

► The effect of cutting speed on the surface integrity and fatigue life of Ti–6Al–4V is investigated.
► Cutting speed has limited influence on surface integrity between 50 m/min and 150 m/min.
► Heat treatment condition has significant influence on surface integrity and fatigue life.