IF钢的性能评价很大程度上取决于其n值、r值,目前广泛采用的机械引伸计方法受环境影响较大,难以获得准确、稳定的结果。为得到准确的r值,同时研究试验过程中影响r值测量准确性的因素,对IF钢进行拉伸试验并结合数字图像相关(DIC)方法对IF钢的n值、r值进行了测定,与通过机械引伸计测量应变的方法所得结果进行比较,同时,通过DIC方法在试样不同位置添加一系列虚拟横向引伸计以分析横向应变测量位置对材料r值测量的影响。试验结果表明,相比于机械引伸计,DIC方法具有更高的稳定性;虚拟横向引伸计测量位置的不同导致试验结果的不同,测量位置距断裂位置越远则结果误差越大,DIC方法可以保证测量位置及结果的准确性。 IF steel performance evaluation depends largely on its n value, r value, the current extensive use of mechanical extensometer method greatly affected by the environment, it is difficult to obtain accurate and stable results. In order to obtain the accurate r value and to study the factors influencing the accuracy of the r value during the test, the IF steel was subjected to tensile test and the digital image correlation (DIC) method was used to determine the n value and r value of IF steel. The results were compared with those obtained by mechanical extensometer. Meanwhile, a series of virtual transverse extensometers were added to the different locations of the specimens by DIC to analyze the effect of transverse strain measurement on material r value measurement. The experimental results show that compared with the mechanical extensometer, the DIC method has higher stability; the difference of the measurement position of the virtual transverse extensometer results in the difference of the test results; the farther the measurement position is away from the fracture position, the larger the error of the result is, the DIC method can Ensure the accuracy of measurement location and result.