Strain Rate Dependence of Stress-Strain Curves in a Ti-Fe-O Alloy
Quantitative expression of stress-strain curve including strain rate dependence in a Ti-Fe-O alloy was studied at temperatures between 77 and 293 K. <br>In order to evaluate the strain-rate-independent component, in the first place, the authors endeavored to obtain the stress-strain curve as the curve at 0 strain rate through relaxation tests under constant crosshead displacement. The relaxation-saturated stress-strain points made a single curve. The authors named this single curve as "Base Curve". The Base Curve was good fitted to the Swift's equation in the following form: σ<sub>Base</sub>(ε)=<i>A</i>(ε+<i>b</i>)<sup><i>n</i></sup>, where σ<sub>Base</sub>(ε) is the stress on the Base Curve, ε the plastic strain, <i>n</i> the exponent, and <i>A</i> and <i>b</i> are coefficients.<br> The stress-strain curves at the strain rate between 2.8×10<sup>-5</sup> and 3.0×10<sup>-2</sup> s<sup>-1</sup> were parallel to the Base Curve. Namely, the strain-rate-dependent component, σ<sup>*</sup>, was independent of strain at a constant strain rate. The relation between σ<sup>*</sup> and strain rate, γ, was expressed in the following form: σ <sup>*</sup>=<i>B</i>γ<sup><i>m</i></sup>, where <i>B</i> coefficient and <i>m</i> exponent.<br> Finally, the equation, σ=<i>A</i>(ε+<i>b</i>)<sup><i>n</i></sup>+<i>B</i>γ<sup><i>m</i></sup>, is derived for the expression of flow stress-plastic strain relation under the deformation at a constant strain rate.
- ISIJ international
ISIJ international 37(10), 1016-1022, 1997-10-15
The Iron and Steel Institute of Japan