AT道岔钢轨在加工过程中出现裂纹。采用化学分析、低倍、金相及夹杂物等方法对该钢轨进行了检验。结果表明,化学成分符合标准要求,低倍组织和显微组织正常;而由于感应线圈与道岔钢轨之间的距离设置不当,在进行感应加热时局部区域出现加热温度过高,在该区域形成不同程度的过烧、过热组织和龟裂纹等缺陷;在随后的锻压加工过程中缺陷又进一步扩展,最终形成较大的裂纹而开裂。

Crack appears when AT switch rail is being made. The results are checked by chemical analysis,macroscopic examination,metallographic examination,and impurity examination. Analyzing indicates that its chemical constitution meets the standard requirement,and its macroscopic structure and metallurgical structure is normal. But the improper distance between induction coil and switch rail,led partial area of excessive high temperature when heatings by induction,which cause overburnt,overheat and shattered crack. The crack further grew during the subsequent forging process and formed bigger crack in the rail-web (lower) area.