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

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/3.0and SPHE/1.8is 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 different 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 50mm gauge and 80mm gauge,the former has larger percentage elongation after fracture and nvalue,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.