某公司一根导热油管在使用过程中发生断裂。采用宏观观察、化学成分分析、金相检验、硬度测试、断口分析等方法，对导热油管的断裂原因进行了分析。结果表明：导热油管经历了高碳铁液修补，使材料的脆性增大；在外力作用下导热油管于薄壁处发生开裂，引起导热油泄漏；在导热油压的作用下，导热油管沿横截面发生脆性断裂。

A heat-transfer oil pipe of a company fractured during use. The methods of macroscopic observation, chemical composition analysis, metallographic inspection, hardness testing and fracture analysis were used to analyze fracture reasons of the heat-transfer oil pipe. The results show that:the heat-transfer oil pipe was repaired by liquid iron containing high carbon, and it increased the brittleness of the material; under the exogenic action, the heat transfer pipe cracked at the position of the thin wall, which led to the heat-transfer oil leak; under the action of the heat-transfer oil pressure, the heat-transfer oil pipe cracked along the cross section.