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高强度双相钢(Dual Phase Steel,DP)板冲压成形的主要缺陷为回弹,而马氏体相是影响回弹的重要因素。把DP600钢试样加热至740℃且保温8 min后水淬,再分别降温至200、260、320℃且保温1 h,以获得多相材料,用U形弯曲模具进行了实际冲压实验。通过SEM测试了钢中马氏体相的体积分数,观察并分析微观组织晶粒形貌;通过拉伸实验,获得了试样的力学性能。分析马氏体体积分数对U形件回弹量的影响,研究了回弹量与铁素体晶粒度的关系。结果表明,马氏体体积分数越大,屈服强度与抗拉强度越高;铁素体晶粒大小对冲压回弹量几乎没有影响。
The main defect of high-strength Dual Phase Steel (DP) sheet stamping is rebound, while the martensitic phase is an important factor affecting rebound. The DP600 steel samples were heated to 740 ℃ for 8 min and then water quenched. The samples were then cooled to 200, 260 and 320 ℃ for 1 h respectively to obtain multiphase materials. The actual stamping experiments were carried out with a U-shaped bending die. The volume fraction of martensite phase in steel was measured by SEM. The grain morphology of the microstructure was observed and analyzed. The mechanical properties of the sample were obtained by tensile test. The effect of volume fraction of martensite on the springback of U-shaped part was analyzed. The relation between springback and ferrite grain size was studied. The results show that the larger the volume fraction of martensite, the higher the yield strength and tensile strength; the ferrite grain size has almost no effect on the amount of stamping rebound.