线材拉伸异常断裂分析

为了研究线材拉伸试验过程中试样断裂处位于夹具根部的原因,从而避免这一现象再次发生,影响检验数据,进行了模拟试验及生产应用。结果表明:夹持试样时,没有满足试样夹持部分长度至少为夹具长度的3/4时,线材会出现断裂在夹具根部的现象,使抗拉强度偏低,并且影响断面收缩率、断后伸长率的测量,使断面收缩率和断后伸长率不合格,产生无效数据。因此,在保证上、下夹具同轴度以及加持力正好合适的前提下,通过改变试样夹持部分长度进行拉伸试验,解决了线材拉伸试验断在夹具根部的问题。

Analysis of abnormal fracture in tension of wire rod

In order to investigate the reason why the wire rod sample was broken at the root of fixture during the tensile test， and to avoid the occurrence of this phenomenon which affected the testing results， the simulation test and production application were carried out. The results showed thatthe wire rod sample would be broken at the root of fixturewhen the clamping part of sample did not meet the requirement that the clamping length was at least 3/4 of the fixture length. As a result， the tensile strength would be lower. Moreover， it would affect the measurement of reduction of area and elongation after fracture， resulting in unqualified testing results and invalid data.On the premise of ensuring the coaxiality of upper and lower clamps as well as proper clamping force， the tensile tests were conducted by varying the clamping length of sample.The problem that the wire rod sample was broken at the root of fixture in tensile test was finally solved.