样件标距对汽车用热轧钢板拉伸性能的影响

Effect of sample gauge on tensile properties of hot-rolled steel sheets for automotive application

文章研究测试标距对汽车用热轧钢板SAPH370/1.8/2.2/2.5、SAPH440/2.3、SPHC/3.0和SPHE/1.8等材料的强度和塑性指标以及应力应变曲线的影响。试验表明:对汽车用热轧钢板,采用公式计算的断后伸长率与实测结果基本相符,说明不同标距下的断后伸长率可换算到同一标距下进行比较;测试标距对热轧板的强度指标基本无影响;50mm标距的断后伸长率和n值大于80mm标距的,而r值则相反;测试标距对于材料的工程应变曲线和真实应力应变曲线的轨迹也有影响。因此,在设计中,应慎重选择不同标距的汽车用热轧钢板,以免影响产品的可靠性和设计的有效性。

The influence of sample gauge on the strength, plastic parameters and stress-strain curve trace of hot-rolled steel sheets including SAPH370/1. 8/2. 2/2. 5, SAPH440/2.3, SPHC/3.0 and SPHE/1.8 is studied respectively. The experimental results show that as for the hot-rolled steel sheets for automotive application, the percentage elongations after fracture calculated by formula are basically consistent with the measured results, and the percentage elongations after fracture under dif- ferent gauges can be compared by converting to the same gauge. The sample gauge has almost no effect on the strength of materials. For the samples with 50 mm gauge and 80 mm gauge, the former has larger percentage elongation after fracture and n value, and lower r value. The sample gauge has influence on the trace of both the engineering stress-strain curve and the true stress-strain curve. Therefore, the hot-rolled steel sheets with different gauges should be carefully chosen in the design so as not to affect the reliability of the product and the validity of the design.