Dynamic strain-ageing of unalloyed titanium during compression at strain rates of 0.05 to 32s^-1 and temperatures of 303 to 573 K

Dynamic strain-ageing is a well known phenomenon in metal working, which phenomenon, however, is objectionable from the formability point of view. Dynamic strain-ageing is dependent upon the chemical composition of the work-metal, the deformation, the deformation rate and the temperature. The loss in ductility and the variation of the flow stress, the strength coefficient and the strain-hardening exponent, with variation in temperature, characterise the onset of dynamic strain-ageing. A sudden increase in the work-metal temperature due to adiabatic heating can also contribute to the occurrence of dynamic-strain ageing. In this work the interaction of: (i) the true stress; (ii) the work-hardening rate (θ=dσ/dε{lunate}); and (iii) the strain-rate sensitivity index (γ=Δσ/Δln dot ε{lunate}), with temperature, has been analysed to ascertain the onset of dynamic strain-ageing in the compression testing of commercially pure titanium. © 1990.