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针对B340/590DP双相钢在强塑积较高的温度区间150℃~300℃内变形时应变硬化指数n、强化系数K等材料参数随变形温度和应变速率变化波动较大、规律性不强的特点,采用分段双线性插值方法,提出了综合考虑变形温度、应变速率及应变路径影响的B340/590DP双相钢温热成形应力-应变模型和韧性破裂准则。并借助有限元仿真技术,通过比较不同变形路径下的仿真结果与胀形实验结果,修正仿真模型及韧性破裂准则中与应变路径相关的系数,获得其与应变路径系数r的函数关系。最后,将应力-应变模型和破裂准则引入DYNAFORM软件预测板材的温热成形极限,预测结果与实验结果吻合较好,验证了所建模型和破裂准则的正确性。
In the case of B340 / 590DP dual-phase steels, the strain hardening index n and the strengthening coefficient K are greatly fluctuated with the deformation temperature and strain rate when the deformation is within the range of 150 ℃ ~ 300 ℃, and the regularity is not strong The stress-strain model and ductile fracture criterion of B340 / 590DP dual-phase steel with thermomechanical forming considering the influence of deformation temperature, strain rate and strain path are proposed by the piecewise bilinear interpolation method. By means of finite element simulation, the relationship between strain path and strain coefficient is obtained by comparing the simulation results under different deformation paths with the experimental results of bulging. The correlation coefficients between strain path and the simulation model and the coefficient of strain path are obtained. Finally, the stress-strain model and fracture criterion are introduced into the DYNAFORM software to predict the hot forming limit of the sheet. The prediction results are in good agreement with the experimental results, which verify the correctness of the established model and the fracture criterion.