通过理化检验和宏、微观检查，分析了车轮崩裂失效的原因。结果表明,车轮存在严重的冶金缺陷——成分偏析，致使车轮轮辋中部、辐板等部位韧性差，脆性大；当有上述缺陷的车轮运行在下坡道制动时，产生的制动热应力和由于车轮成分偏析所产生的组织应力共同作用，诱发了轮辋内部产生裂纹并快速扩展，导致碎裂崩轮。

The causation of wheel breaking-up was analyzed through physical and chemical inspection, macroscopical and microscopical examination. There has severe metallurgical defect-aliquation on the wheel and that made the rim and web become crisp; cracks were initiated and expanded rapidly because thermal stress from breaking and structural stress from aliquation acted together during service, then the wheel breaking-up as a result. For the sake of avoiding wheel damage which caused by metallurgical defects and endangered train operation, some suggestions were proposed.