冷拔丝试件如断在原标距长度中央1/3以外,采用“移位法”计算延伸率,由于测量累计误差大,延伸率又较小,往往测得的延伸率不够精确,另外,断在标外的也不少,重试工作多,鉴于这些情况,可采 If the cold drawing sample is broken off from the central one-third of the original gauge length, the “extension method” is used to calculate the elongation rate. Because the measurement error is large and the elongation is small, the measured elongation rate is not accurate enough. There are also many out of substandards, and there are many retests. In view of these circumstances, it is