针对汽车用冷轧薄钢板材料拉伸试验中, 试样标距的规定不完全相同, 断后伸长率(A)没有可比性, 给材料评价带来不便的问题, 对多种冷轧薄钢板进行了不同标距试样的拉伸试验, 并进行了对比分析。结果表明: 与断后伸长率相比, 最大力总延伸率(Agt)与试样标距没有关联, 是材料拉伸曲线上与抗拉强度(Rm)点直接对应的一个固有特征点参数; 随着计算机辅助测试技术的进步, 目前各冷轧薄钢板和汽车生产厂家都已能方便地测出Agt, 故提出了采用不受试样标距制约的反映材料塑性本质特性的Agt作为冷轧板选材延伸率评价指标的构想。

Tensile tests of specimens with different gauge lengths of multiple sorts of cold-rolled steel sheets were performed to solve the problem that the rules of specimen gauge lengths are not all the same and percentage elongations after fracture (A) are not comparable, resulting in the inconvenience of selecting materials for autos. Results show that, compared with the percentage elongation after fracture, percentage total extension at maximum force (Agt) is not related to the gauge length of tensile specimen, it is a inherent characteristic parameter corresponding to the point of tensile strength (Rm) on the tensile curve of material. With the development of computer-aided test technology, nowadays, the Agt parameter could be conveniently measured by cold-rolled steel sheet factories and auto factories. It is suggested that Agt, which is not regulated by specimen gauge length and reflectes the essential characteristics of plastic material, is the ideal index for evaluating the elongation rate of cold-rolled steel sheet materials .