Constitutive equation in ambient temperature creep of α-Ti

The constitutive equation in ambient temperature creep region of α-Ti was investigated by performing creep tests on solute-strengthened and/or cold-rolled titanium. Increasing solute content and/or thickness reduction decreases the steady state creep rate. The stress exponent increases with solute content, but it is independent of thickness reduction in low stress. Then, the microyielding stress, σmy, is introduced to express the stress at which dislocations start moving. The stress exponent in ε̇s− (σ−σmy) graph becomes almost constant with the value of three even in the solute-strengthened and/or cold-rolled titanium. The constitutive equation for ambient temperature creep in α-titanium is proposed as ε̇s=A (S) × (b/d) p× {(σ−σmy) /E} n×exp (−Q/RT) , where n≃3, p≃1 and Q≃20 kJ/mol. The deformation mechanism map of titanium with ambient temperature creep region including microyielding stress is proposed.