对在日常检验过程中出现的两个伸长率异常偏低的试样进行了理化检验和分析,并与一个合格试样进行了比较。结果表明:由于连铸铸坯内存在大量非金属夹杂物,导致基体与夹杂物之间产生内应力,因此在拉伸过程中促使裂纹的迅速扩展,形成穿晶裂纹和空洞,最终呈现伸长率偏低的结果。

The chemical analysis and physical testing were processed on two low-elongation samples which were found in the regular testing experiment. One eligible sample was chosen to compare the difference among them. The results showed that the massive non-metallic inclustions which existed in the continuous casting slab caused internal stress between the substrate and the inclustions. The stress enable the crack to expand rapidly in the tensile test. The trans-grain cracks and pinholes formed in the process and finally caused low elongation of the sample.