GB/T 21143—2014中直流电位法的讨论

电位法作为准静态断裂韧度测量标准GB/T 21143—2014中推荐的方法之一，在某些情况下可对常用的柔度法不便测量的试样进行辅助测量。为了验证电位法在断裂韧度测量中的实际效果，按照标准中规定的直流电位法对试样进行了断裂韧度的测试，并将测试结果与柔度法进行对比。结果发现：GB/T 21143—2014中的方法1，即间接测量法可以更准确简便地测量裂纹的长度，结果与柔度法相当；而方法2，即直接测量法，在实际试验中不容易控制裂纹测量的准确性，准确性与便捷性均不如方法1。

Discussion on direct current electric potential difference method in GB/T 21143-2014

Direct current electric potential difference (DCEPD) method is one of recommended methods in GB/T 21143-2014 for the determination of quasistatic fracture toughness. In some cases, it can be used for the auxiliary measurement of sample which is inconvenient to be tested by the common compliance method. To verify the actual effect of DCEPD method in fracture toughness measurement, the fracture toughness of sample was tested according to the DCEPD method specified in standard, and the measuring results were compared with the compliance method. It was found that the Method 1 in GB/T 21143—2014 (i.e., indirect measurement method) was more convenient and accurate to measure the length of cracks, and the results were consistent with those obtained by the compliance method. For the Method 2 (i.e., direct measurement method), it was not easy to control the measurement accuracy of cracks in actual test, and both the accuracy and convenience were inferior to the Method 1.