基于试验得到的显微组织建立了7Mn钢的代表性体积单元(RVE)模型,采用ABAQUS软件对温轧和不同温度(600~630 ℃)退火后7Mn钢在单轴拉伸过程中的组织演变和应力、应变分布进行模拟,并与试验结果进行对比。结果表明:当残余奥氏体沿着拉伸方向分布时,更容易发生协同变形,从而缓解铁素体中的应变集中,使体系处于较高的应力状态;在600 ℃退火后残余奥氏体稳定性较高,均匀塑性变形结束时仅有部分残余奥氏体转变为马氏体,而630 ℃退火后拉伸时残余奥氏体大部分转变为马氏体,模拟得到残余奥氏体含量与试验结果相吻合,相对误差小于5%,验证了基于RVE模型模拟组织演变的准确性;在615,630 ℃退火后,模拟得到应力-应变曲线与试验结果吻合较好,相对误差小于5%,验证了基于RVE模型模拟单轴拉伸行为的准确性,但在600 ℃退火后,由于各相本构模型未考虑到细晶强化和固溶强化作用,导致模拟结果与试验结果存在较大偏差。

Based on the microstructure obtained by test, the representative volume element(RVE) model of 7Mn steel was established. The microstructure evolution, stress and strain distribution during uniaxial tension of 7 Mn steel after warm rolling and annealing at different temperatures(600-630 ℃) was simulated by ABAQUS software and compared with the test results. The results show that when residual austenite was distributed along the tensile direction, it was tended to occur collaborative deformation to alleviate the strain concentration in ferrite and make the system in a high stress state. After annealing at 600 ℃, the residual austenite had high stability, and only part of austenite transformed into martensite at the end of uniform plastic deformation. The residual austenite almost transformed into martensite during tension after annealing at 630 ℃. The simulated residual austenite content was in good agreement with the test results and the relative error was less than 5%, verifing the accuracy of simulating microstructure evolution by RVE model. The simulated stress-strain curves after annealed at 615,630 ℃ were in good agreement with test results, and the relative error was less than 5%, verifing the accuracy of simulating uniaxial tensile behavior by RVE model. There was a large deviation between the simulation and the test results after annealed at 600 ℃ because of ignoring the refinement strengthening and solution strengthening in each phase constitutive model.