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利用光学显微镜、扫描电子显微镜和化学分析手段对断裂的烟气轮机转子叶片进行微观组织、断口形貌、化学成分等观察与分析。结果表明,叶片的化学成分除碳含量偏高外其余元素基本符合K213合金锭标准。叶片的物相组成为奥氏体+γ’+碳化物,γ’与碳化物的分布不均匀,特别是碳化物沿晶界分布弱化了晶界强度。高温工况下长时间运行的叶片在交变热应力作用下力学性能降低,再加上内部缺陷和沿晶分布的脆性相是导致其断裂的主要原因。
The microstructure, fracture morphology and chemical composition of ruptured flue gas turbine rotor blades were observed and analyzed by optical microscope, scanning electron microscope and chemical analysis. The results showed that the chemical composition of the leaves in addition to high carbon content of the other elements are basically consistent with the standard K213 ingot. The phase composition of the blade is austenite + γ ’+ carbide, γ’ and carbide distribution is not uniform, especially carbide along the grain boundary weakening the grain boundary strength. Long-time operation of the blade under high temperature conditions under the action of alternating thermal stress decreased mechanical properties, coupled with internal defects and the brittle phase along the crystal distribution is the main reason leading to its fracture.