【摘要】 EA4T是动车组列车的主要车轴材料,要实现EA4T车轴高效高精度加工,必须研究其切削加工性能。EA4T车轴材料在高温、大应变、高应变率条件下的动态应力应变特征是进行有限元建模和切削仿真的基础,为此,使用分离式霍普金森压杆与微型霍普金森压杆实验系统进行了温度20-800℃、应变率1000-8000s-1范围内材料的动态力学特性测试。结果表明:EA4T车轴材料的最大真实应变可达50%,真实应力随温度的升高而明显减小,并且存在显著的温度软化作用;真实应力随应变率的升高先增大后减小,这是因为在低应变率时存在应变率强化作用、在高应变率时存在应变率软化作用。最后,通过对试验数据的参数拟合改进,建立了高精度的Johnson-Cook本构关系模型。更多还原

【Abstract】 EA4T is the main axle material of multiple unit train. In order to achieve high-performance and high- precision machining of EA4 T axle material,the cutting performance must be studied. The dynamic stress-strain characteristics of the axle material under the condition of high temperatures,large strain and high strain rate are the basis for finite element modeling and cutting simulation. Therefore,testing for dynamic mechanical properties was performed within the temperature range of 20℃ to 800℃ and strain rate range of 1000s^-1to 8000s^-1by Split Hopkinson Pressure Bar（ SHPB） and miniature SHPB test systems. The results show that the maximum true strain of EA4 T axle material could reach 50%. The true stress decreases significantly with the increase of temperature and there is a significant temperature softening effect. The true stress first increases with the strain rate and then decreases. This is due to the strain rate strengthening effect at low strain rate but strain rate softening effect at high strain rate. Finally,a modified Johnson-Cook constitutive model with high accuracy is established by fitting parameters with the experimental data.更多还原