针对在挤压加工道岔轨时出现挤压爆裂和矫直断裂的情况，对断裂钢轨进行了化学成分分析、低倍及金相检验，并采用X-650扫描电镜及EDAX电子探针对断口进行了分析。分析结果表明，断裂钢轨化学成分满足标准要求，低倍组织和显微组织正常，断口呈脆性断裂解理特征，断口处氧化严重。由此认为，造成挤压时道岔轨爆裂和矫直断裂的原因是挤压前加热工艺不当所致。

The AT rail fractured in the extrusion process and straightening process. The chemical composition was analyzed, the marcostructure and microstructure of the fracture-rail was examined. The fracture appearance was analyzed by the X-650 scanning electronic microscope and EDAX electronic probe. The results show that the chemical composition, macrostructure and microstructure are normal, the fracture appearance is brittle crowbarand, and the fracture was oxygenated severely. The conclusion is that the improper heating process is the direct reason of the AT rail′s fracture in the extrusion and strengthening process.