摘要
研究了ＧＨ９８４舰用高温耐蚀合金在７００℃不同时间长期时效以后碳化物的变化。结果表明，合金中碳化物的数量和组成随时效时间的增加略有变化。在标准热处理状态下合金中碳化物的总量为０５２％，而在７００℃长期时效１８０００ｈ后碳化物数量为０６６％并且在碳化物中发现有Ｃｒ元素存在，应力时效可促进碳化物析出。块状和颗粒状碳化物能强化晶界，对合金性能有利。在该合金中σ相除通过ＮｂＣ，Ｔｉ（ＣＮ）→Ｍ２３Ｃ６→σ形核外，还可能直接从ＭＣ碳化物转变而成。
GH984 alloy is an anticorrosion superalloy and can be used as a superheater tube material in the making of large scale vessel. The change of carbides during long term aging at 700℃ for various time has been investigated. The results showed that the amount and chemical compositions of the carbides are lightly changed with aging time. The total amount of carbides at standard treatment condition is about 0.52%, after aging at 700℃ for 18000h their total amount rises to about 0.66% in the alloy and Cr element is found in the carbides. The stress can accelerate their precipitation. The bolcky and particular carbides are benifical to mechanical properties of the alloy, because of strengthening grain boundaries. It is possible that the σ phase can be transformed form MC carbide directly, beside NbC, Ti(CN)→M 23 C 6→σ.
关键词
抗腐蚀
高温合金
碳化物
长期时效
anticorrosion superalloy,\ carbide,\ long term aging
