【摘要】 对45号钢在不同环境温度(25 300℃)和不同应变率(10-4～103s-1)的σ ε关系进行了研究。修正了Johnson Cook模型中的应变率强化系数C,确定了45号钢的本构关系。金相观察表明,与应变率强化相比,较高的环境温度使硬化速率降低,且占主要因素,其结果使材料的强度降低。透射电镜分析表明,高应变率在使位错运动的能量提高的同时,增加了位错在晶界处的阻力,而较高的环境温度则为位错提供了较多的滑移面和滑移方向,其结果是使材料更容易压缩。更多还原

【Abstract】 In this paper the σ ε relation of 45 steel under different initial temperatures (25～300 ℃) and strain rates(10-4～103 s-1) has been studied with the split Hopkinson press bar (SHPB) and the MTS (Materials test system), its constitutive relation is determined then.The metallography observation show that the reduction of hardening under higher ambient temperatures prevails over the strain rate hardening, and results in a reduction in material strength. Meanwhile the TEM analysis indicates that the high strain rate raises both the energy of dislocations and the resistance to them at crystal boundaries. The higher ambient temperatures allow more slip surfaces and directions for dislocations and result in a higher compression of the material.更多还原