Effect of grain size on compressive behaviour of titanium at different strain rates

An investigation was conducted to evaluate the dependence on grain size of the compressive deformation of commercial purity (CP) Ti. Tests were performed at room temperature using grain sizes from coarse-grained CG (20 μm) to ultrafine-grained UFG (500 nm) and nanocrystalline NC (90 nm) with testing strain rates in the range from 0.01 to 10 s−1. The results show the flow stress and the strain rate sensitivity of CP Ti increase with decreasing grain size. Work hardening dominates at all strain rates in CG Ti but it balances with flow softening at 0.01 and 0.1 s−1 in UFG and NC Ti and there is obvious flow softening in these two materials at 10 s−1.