3044 t/h超超临界锅炉磨煤机拉杆断裂原因

某电厂3044 t/h超超临界锅炉磨煤机拉杆发生断裂,通过化学成分分析、断口分析、力学性能测试和金相检验等方法对拉杆断裂原因进行了分析.结果表明:该拉杆供货态热处理质量较差,导致强度和冲击韧性指标不合格,且磨损补焊处因热处理不到位而产生冷裂纹,长期在往复拉应力及弯曲应力的作用下,裂纹疲劳扩展,最终导致拉杆疲劳断裂.

Cause of Fracture on Pull Rod of Coal Mill in 3044t/h Ultra Supercritical Boiler

Coal mill pull rod of 3044 t/h ultra supercritical boiler in a power plant fractured.The causes of fracture on pull rod were analyzed by means of chemical composition analysis,fracture analysis,mechanical property test and metallographic examination.The results show that the quality of heat treatment of pull rod was poor,which resulted in the unqualified indexes of strength and impact toughness,and the cold crack produced at the worn repair welding due to insufficient heat treatment.Under the action of long-term reciprocating tensile stress and bending stress,the fatigue crack propagated and finally led to fatigue fracture of pull rod.