YL82B盘条抗拉强度异常原因分析

Cause analysis of abnormal tensile strength of YL82B wire rod

YL82B盘条抗拉强度和断面收缩率出现异常。将异常试样与正常试样进行对比,出现抗拉强度和断面收缩率异常的盘条金相组织、索氏体化率均无异常,符合国家相关标准要求,晶粒度小于正常试样;采用扫描电镜测量试样心部、直径1/4处、边部索氏体片层间距,发现异常试样都比正常试样的索氏体片层间距大;显微硬度测试发现,异常试样的显微硬度值均低于正常试样,正常试样索氏体片层间距小的位置显微硬度大。试验结果表明,YL82B盘条发生异常是因为晶粒较粗大、索氏体片层间距较大,力学性能受到影响,导致其抗拉强度和断面收缩率异常。

Abnormal tensile strength and section shrinkage of YL82B wire rod were analyzed.Comparing abnormal sample and normal sample,microstructure and sorbite rate of wire rod with abnormal tensile strength and section shrinkage are not abnormal,which meets requirements of relevant national standards,grain size is smaller than normal sample.Scanning electron microscopy was used to measure sorbite lamellar spacing at core,diameter 1/4 and edge of the sample.It was found that sorbite lamellar spacing of abnormal samples was larger than that of normal samples.Microhardness test showed that microhardness values of abnormal samples were all lower than that of normal samples,and microhardness of normal samples was higher in position with small sorbite lamellar spacing.Test results show that mechanical properties of YL82B wire rod are affected by coarse grain size and large distance between sorbite lamellar spacing,which leads to abnormal tensile strength and section shrinkage.