基于不同失稳理论的DP780双相钢成形极限预测

Forming Limit Prediction of DP780 Dual Phase Steel Based on Different Instability Theories

采用板材综合成形试验机对DP780双相钢进行极限应变试验,分别基于C-H失稳理论和M-K凹槽失稳理论搭载Yld2000屈服准则和幂指数硬化模型对DP780双相钢成形极限曲线进行预测,并与试验结果进行对比。结果表明:基于M-K凹槽失稳理论和C-H失稳理论获得的成形极限曲线对成形极限的预测精度分别为97.97%和95.82%;初始厚度不均匀度越大,钢板表面越光滑,越有利于成形;当初始厚度不均匀度为0.992时,M-K凹槽失稳理论对DP780双相钢成形极限的预测精度最高,相对误差为0.66%,在实际冲压生产中,当初始厚度不均匀度取0.992时,该理论模型可作为获取DP780双相钢成形极限曲线的一种可靠方法。

Limit strain test of DP780 dual phase steel was carried out with a comprehensive sheet forming test machine. Based on C-H instability theory and M-K groove instability theory, the forming limit curve of DP780 dual phase steel was predicted by using Yld2000 yield criterion and power exponent hardening model, and compared with the test results. The results show that the prediction accuracy of forming limit curve based on M-K groove instability theory and C-H instability theory for the forming limit was 97.97% and 95.82%, respectively. The larger the initial thickness non-homogeneity, the smoother the steel plate surface, which was more conducive to forming. When the initial thickness non-homogeneity was 0.992, the M-K groove instability theory had the highest accuracy in predicting the forming limit of DP780 dual phase steel, with a relative error of 0.66%. The theoretical model can be used as a reliable method to obtain forming limit curve of DP780 dual phase steel in actual stamping production when the initial thickness non-homogeneity was 0.992.