关键词: Johnson-Cook本构模型, 纯铁, 高应变率, 流变应力, 应力—应变曲线

Abstract: The experiment of dynamic mechanical behaviors test of pure iron is carried out at wide temperatures range (293~1 073 K) and high strain rates (2 000~8 500 s–1) with split Hopkinson pressure bar, which is installed with heating device and synchro assembly system. The stress-strain curves of material under temperature-strain rate coupling actions are obtained. The mechanism of effect of temperature and strain rate on the plastic flow stress of pure iron is discussed. The studies show that the pure iron has evident heat softening effect, strain rate strengthening effect and strain hardening effect, and flow stress increases with temperature decreasing and strain rate increasing. The Johnson-Cook constitutive model that is fitted by stress-strain curves obtained from experiments can provide satisfactory prediction of the plastic flow stress of pure iron.

Key words: Flow stress, High strain rate, Johnson-Cook constitutive model, Pure iron, Stress-strain curve