中文摘要：

硼钢的高温本构方程是热冲压数值模拟不可缺少的数学模型,它反映了流动应力与应变、应变速度以及温度之间的依赖关系。为了研究热冲压硼钢B1500HS高温时的流变力学行为,采用Gleeble 1500D热模拟试验机,在600～900℃温度区间,分别以0.01 s^-1、0.1 s^-1、1.0 s^-1、10 s^-1的应变速度对硼钢B1500HS试样进行等温单向拉伸试验,计算得到各相应测试条件下的正应力—应变曲线。采用包含变形激活能和变形温度的双曲正弦形式修正的Arrhenius关系来描述硼钢奥氏体组织的热激活变形行为。通过对试验数据进行拟合回归分析,得到与应变量相关的各材料参数,以及与应变速度、变形温度相关的流变应力关系式。试验结果显示,流动应力随着变形温度的降低而增大,随着形变速度的升高而增大。计算结果表明：流变应力关系式的计算结果与试验数据的吻合度较好。

英文摘要：

Constitutive relationship of boron steel at high temperature is one of the most necessary mathematical models in the numerical simulation of hot stamping.It describes the relationship of the flow stress with strain,strain rate and temperature.In order to build the constitutive equations of boron steel B1500HS,some isothermal uniaxial tensile tests are performed at 600～900 ℃ with strain rate 0.01 s^-1,0.1 s^-1,1.0 s^-1 and 10 s^-1 by Gleeble 1500D thermo-mechanical simulator,and the true stress-strain curves at the relative conditions are gained.The modified Arrhenius model,which is a hyperbolic sine function including the deformation activation energy and deformation temperature,is used to describe the hot deformation activation character of austenite microstructure of boron steel.The material parameters depending on the strain,and the constitutive equations depending on the strain rate and deformation temperature,are attained by the regression analysis of experimental data.The experimental results show that,the flow stress rises with the decrease of the deformation temperature and the flow stress rises with the increase of the strain rate.The results show that the computational data using the constitutive relationships are consistent with the experimental data.