CAJ | 학술논문

对某600 MW超临界机组高温过热器弯头在运行不到1 000 h发生开裂现象进行了外观检查、显微分析,同时对冷弯成型工艺过程进行数值模拟。研究表明：亚稳态不锈钢TP347H冷弯成形时内弧应变量超过ASME规范要求,产生马氏体相变,形成点蚀源,在残余应力与高温运行时热应力的共同作用下引起的内弧面开裂是弯头寿命降低的主要原因。
대모600 MW초림계궤조고온과열기만두재운행불도1 000 h발생개렬현상진행료외관검사、현미분석,동시대랭만성형공예과정진행수치모의。연구표명：아은태불수강TP347H랭만성형시내호응변량초과ASME규범요구,산생마씨체상변,형성점식원,재잔여응력여고온운행시열응력적공동작용하인기적내호면개렬시만두수명강저적주요원인。
A macrostructure examination and scanning electron microscopy analysis was made on the failure of the high-temperature super-heater elbow which was operated less than 1 000 h.The process of pipe cold bending was simulated.It shows that： the forming strain at the intrados of metastable state stainless TP347H steel,while bending exceeded ASME standard,causes martensitic phase transformation.It was the pitting source of the tube.The intergranular fracture which was caused by both the residual stress and the heat stress acted on the coarse precipitate at the intrados is the main reason of the drop of the elbow life.