中文摘要：

采用金相、SEM和XRD等方法,对原始及不同服役阶段的F12马氏体耐热钢试样的性能和组织结构进行了分析和比较.结果表明：随着服役时间的延长,试样的力学性能明显下降;在不同服役阶段,F12马氏体耐热钢试样的显微结构发生了明显变化,不仅出现原奥氏体晶界处碳化物的粗化、基体组织中α-Fe的晶格常数减小,且断裂态马氏体组织完全分解,并在晶界粗化的碳化物处形成蠕变孔洞.马氏体组织分解、碳化物粗化和基体组织合金元素贫化是直接导致材料性能下降的原因.

英文摘要：

Mechanical properties and microstructures of F12 martensite heat-resistant steel samples with different service hours have been analyzed and compared using OM, SEM and XRD method.Results show that with the rise of service time,mechanical properties of above samples degrade severely,due to great variation of the microstructures,such as coarsening of carbides precipitated at original austenite grain boundary,reduction of α-Fe lattice constant in the matrix,complete decomposition of broken and fragmental martensite as well as formation of creep holes in coarsening carbides at grain boundary.Martensite decomposition,carbide corsening and depletion of alloying elements in the matrix are direct reasons leading to the degradation of material properties.