IF钢在轧制极薄带过程中的力学性能尺寸效应研究

Research on size effect of mechanical properties of IF steel during the process of preparing foil by cold rolling

采用同步轧制与异步轧制相结合的方法,在无中间退火的条件下,制备了不同厚度的IF钢带材。利用光学显微镜、X射线衍射仪和拉伸试验机对实验钢进行了微观组织分析和力学性能测试。实验结果表明,IF钢在冷轧制备极薄带的过程中存在力学性能的尺寸效应,具体表现形式为屈服强度和抗拉强度随着厚度的减小先增加而后降低。轧制过程中位错密度的增加是导致强度升高的原因,而当极薄带的厚度小于临界值时,位错密度随厚度的减小而降低,这导致了强度随着厚度的减小而降低。

In present study,IF steel strips withdifferent thicknesses were prepared by combination of symmetric rolling and asymmetric rolling without intermediate annealing.The microstructure and mechanical properties of tested steel were investigated by optical microscopy,X-ray diffraction and tensile testing machine.The results show that size effect ofmechanicalpropertiesof IF steel takes place during preparing foil process by cold rolling.Specifically,the yield strength and ultimate tensile strength first increase and then decrease as the thickness decreases.The increase in strength is caused by the increase of dislocation density during cold rolling.When the foil thickness is less than the critical value,dislocation density decreases with decreasing thickness,which results in the decline of strength with the decrease of thickness.