根据GB/T 228.1-2010的技术要求，金属材料断后伸长率的测量方法通常包括人工测量和利用引伸计自动测量两种方法。由于铍材拉伸试验时试验机无法夹持直接购买的标距为25 mm的引伸计，为了满足标准对引伸计使用的技术要求，重新设计了引伸计的刀口，并将自动测量结果与人工测量结果进行了比较。结果表明：采用改进后的引伸计可以准确、快速地自动测量铍材试样的断后伸长率。

According to the technical requirements of GB/T 228.1-2010, the test methods of percentage elongation after fracture of metal materials usually include manual measurement and automatic measurement with extensometer. Because the testing machine could not clamp the extensometer with a gauge distance of 25 mm purchased directly during the tensile test of beryllium material, in order to meet the technical requirements of the standard for the use of extensometer, the blade of extensometer was redesigned and the test results were compared with the manual measurement results. The results show that the improved extensometer could be used to measure the percentage elongation after fracture of beryllium samples accurately and rapidly.