Incoloy800H合金管材服役过程的开裂机制

Cracking mechanisms of Incoloy800H alloy tube under servicing conditions

利用光学金相、扫描电镜、电子探针等手段对制氢转化炉Incoloy800H管材服役后的组织损伤特征进行分析,并借助弹塑性有限元法分析了管材服役过程温差应力与管材开裂的关联性。结果表明,Incoloy800H管材在服役过程中发生了晶界氧化、晶间腐蚀及元素偏聚现象,管材内壁附近出现3个区域(氧化区,贫碳化物区,碳化物区),其中贫碳化物区深度可达100μm;服役过程贫碳化物区晶界抗蠕变能力的下降及服役过程中管材内壁周向温差应力的综合影响导致Incoloy800H管材服役过程裂纹的萌生及扩展。

By using OM,SEM,EPMA analysis,microstructure damage characteristics of Incoloy800 H pigtail tube used in hydrogen reforming furnace under servicing conditions were investigated,and the relationship between thermal stress induced by temperature difference and the initial and propagation of the crack in the inner tube was analyzed by using FEM simulation. The results show that the boundary oxidation,inter-crystalline corrosion and element segregation occur in the inner wall of Incoloy800 H pigtail tube during its servicing process,and resulting in three regions including oxidation region,carbide free region and carbide region appeared in the inner wall of this tube. The main failure reasons of the tube are the interaction of the decreasing of creep resistance of grain boundary and the circumferential temperature difference stress in the inner wall of the tube during its servicing process.