纯铁高温高应变率下的动态本构关系试验研究

利用带有加热装置和同步组装系统的分离式Hopkinson压杆装置对纯铁进行宽温度范围(293～1073K)、高应变速率(2000～8500s-1)下的动态力学性能测试试验,获得材料在不同温度和应变率耦合作用下的应力—应变曲线,从中探讨温度和应变率对纯铁塑性流动应力的影响机制。研究表明,纯铁具有明显的热软化效应、应变率强化效应和应变强化效应,流变应力随温度的降低和应变率的增加而提高;利用所测的应力—应变曲线拟合的Johnson-Cook本构模型可以较好地预测纯铁的塑性流变应力。

Experimental Research on the Dynamic Constitutive Relation of Pure Iron at Elevated Temperatures and High Strain Rates

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.