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在变形温度为1123~1423 K和应变速率为0.01~10 s-1条件下,对DP590高强钢进行高温热拉伸试验,得到其真应力-真应变曲线,分析了温度和应变速率对DP590高强钢热变形时流动应力的影响。结果表明,当应变量一定时,流动应力随应变速率的升高和温度的降低而增大。基于热拉伸试验数据,通过线性回归分别确定了在峰值应力下DP590高强钢的高温材料常数:应变硬化指数n=3.194,热变形激活能Q=508.29 k J·mol-1,α=0.0153和A=2.126×1017s-1。构建了DP590高强钢的Arrhenius双曲正弦本构关系,与试验值相比,模型的最大误差为7.8%,最小误差为0.18%。根据DMM动态材料模型建立了DP590高强钢在应变为0.3条件下的热加工图,确定了DP590高强钢的适宜热成形区为:应变速率为0.01~0.1 s-1,变形温度为1250~1375 K。
Under the condition of deformation temperature of 1123-1423 K and strain rate of 0.01-10 s-1, the high-temperature hot tensile test of DP590 high-strength steel was carried out and its true stress-true strain curve was obtained. The effect of temperature and strain rate on the strength of DP590 Effect of Flow Stress on Hot Deformation of Steel. The results show that when the amount of strain is constant, the flow stress increases with the increase of strain rate and the decrease of temperature. Based on the data of hot tensile test, the high temperature material constants of DP590 high strength steel under peak stress were determined by linear regression respectively: strain hardening index n = 3.194, thermal deformation activation energy Q = 508.29 kJ · mol-1, α = 0.0153 and A = 2.126 × 1017s-1. The Arrhenius hyperbolic sine constitutive relationship of DP590 high strength steel was constructed. Compared with the experimental data, the maximum error of the model was 7.8% and the minimum error was 0.18%. According to the dynamic material model of DMM, the hot working diagram of DP590 high-strength steel under the strain of 0.3 was established, and the suitable thermoforming zone of DP590 high-strength steel was determined as follows: the strain rate is 0.01-0.1 s-1, the deformation temperature is 1250-1375 K .