Carbide transformation in carburised zone of 25Cr35NiNb+MA alloy after high-temperature service. (2nd January 2016)

• Record Type: Journal Article
• Authors: Liu, Chunjiao; Chen, Xuedong; Chen, Tao; Nie, Defu; Wang, Lu
• Is Part Of: Materials at high temperatures. Volume 33:Number 1(2016)
• Page Start: 98
• Page End: 104
• Publication Date: 2016-01-02
• Subjects: 25Cr35NiNb+MA alloy -- Carburisation -- M7C3 -- M23C6 -- Dislocation wall; Materials at high temperatures -- Periodicals; High temperatures -- Periodicals; 620.1121705
• DOI: 10.1080/09603409.2015.1130330
• Languages: English
• ISSNs: 0960-3409

Abstract

Abstract : Microstructure evolution due to carburising of a 25Cr35NiNb+MA ethylene pyrolysis furnace tube was investigated after service for approximately 4 years. The microstructure of 25Cr35NiNb+MA alloy was examined by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) equipped with energy-dispersive X-ray spectroscopy and high-resolution transmission electron microscopy (TEM). The results revealed that M23 C6 carbides of the 25Cr35NiNb+MA alloy had coarsened and transformed to M7 C3 carbides with a heavily faulted structure during carburising. The content of M7 C3 carbide increased closer to the inner wall. A large number of dislocations had been observed surrounding the carbides and some formed dislocation walls. The carbide transformation mechanism and the effect of the dislocation walls are discussed.