表面凹槽形态对Q-P-T钢成形能力预测的影响

Influence of Surface Groove Morphology on Formability Prediction of Q-P-T Steel

为了确定成形极限图(FLD)理论的凹槽模型中合理的凹槽角度和凹槽深度比,以新型淬火-分配-回火(Q-P-T)钢为研究对象,分别制备了凹槽深度比为5%,10%,15%,25%和凹槽角度为45°,60°,90°的拉伸试样,经单轴拉伸试验后,采用不同的本构模型对拉伸曲线进行拟合,随后利用Swift-Hill公式对单轴拉伸条件下的极限应变值进行了计算,并将理论预测值与经验数据进行比较。结果表明:合适的FLD理论计算应取凹槽深度比为5%左右,凹槽角度等于或小于45°;单轴拉伸条件下极限应变值的计算方法为构成完整FLD的其它加载方式下的极限应变理论预测奠定了基础。

In order to determine the reasonable groove angle and groove depth ratio in groove models of forming limit diagram （FLD） theory, the novel quenching-partitioning-tempering （Q-P-T） steel was investigated. Some tensile samples with different groove angles （45%, 60%, 90%） and groove depth ratios （5 %, 10%, 15 %, 25 %） were prepared, and their uniaxial tests were also performed. After that, different constitutive models were used to fit the tensile curves, and the strain limit values under uniaxial tension were calculated by using Swift-Hill equation and compared to the empirical data. The results indicate that the most suitable situation for predicting FLD was determined at the groove depth ratio being 5~ and the groove angle being equal to or smaller than 45%. The calculation method of strain limit values under uniaxial tension is the base of those of strain limit values under other loading modes composing whole FLD.