试样标距对800MPa级DP钢准静态拉伸变形行为的影响  

The effect of gauge length on quasi-static tensile behavior of 800MPa DP steel

作　　者：郭必檬[1] 王武荣[1,2] 韦习成[1] 羊军[3] 史刚[3] 

机构地区：[1]上海大学材料科学与工程学院,上海200072 [2]上海交通大学机械与动力工程学院,上海200246 [3]上海汽车集团股份有限公司技术中心车身部,上海201804

出　　处：《塑性工程学报》2011年第1期91-95,共5页Journal of Plasticity Engineering

基　　金：国家自然科学青年基金资助项目(51005144);上海汽车工业科技发展基金资助项目(0910);上海市优青科研基金

摘　　要：随着对汽车安全性和燃油经济性的要求越来越高,先进高强度钢在车身上的应用比例逐渐增大。文章研究了800MPa级双相钢(DP钢)在应变速率10-3s-1条件下,不同原始标距L0对其性能的影响。结果显示,原始标距L0减小,基本不影响材料的屈服强度Re、抗拉强度Rm和最大力非比例伸长率Ag,但断后伸长率A显著增大,从而获得较大应变下的应力应变本构关系。该结果可为数值模拟设计者在设计过程中,定义材料力学属性提供参考,为小圆角等较小当量变形部位,提供更为准确的塑性流变关系。采用有限元模拟了不同L0试样拉伸过程,揭示出断后伸长率A发生变化的原因。藉SEM,分析了试样颈缩区的变形组织和断口形貌,探讨了其断裂机理。研究可为超高强度钢在汽车上的应用提供参考。Recently, with the increasing demand for automobile safety and fuel economy, the need for the application of Advanced High Strength Steel （AHSS） for automobile body stamping is increasing. The effect of original gauge length on quasi-static tensile behavior of 800MPa DP （Dual Phase） steel was studied. The results show that with the decrease of original gauge length at strain rate 10^-3 s^-1, the yield strength Re, tensile strength Rm and percentage non proportional elongation at maximum force Ag remain unchanged but the percentage elongation after fracture A increase notably. The constitutive relation of stress and strain under the condition of large strain is then obtained. The results provide reference for defining the mechanical properties of material in the process of numerical simulation design, and provide more accurate plastic flow behavior for small equivalent deformation regions. FEM analyses performed on tensile process of samples with different original gauge lengths reveal the reason for the changing of percentage elongation after fracture A. Moreover, deformed microstructure of Necking region and tensile fracture surface of the samples were analyzed by SEM and the fracture mechanism was presented. The study provides reference for the application of AHSS in automobile industry.

关 键 词：DP钢 原始标距长度 FEM 断裂机理 

分 类 号：TG142.1[一般工业技术—材料科学与工程]