Microstructural characterization of modified 25Cr-35Ni centrifugally cast steel furnace tubes

Journal Article · Tue Oct 15 04:00:00 EDT 2002 · Materials Characterization

DOI:https://doi.org/10.1016/S1044-5803(03)00013-5· OSTI ID:20748674

Almeida, Luiz Henrique de; Ribeiro, Andre Freitas; Le May, Iain

HP steels modified with Nb and Nb-plus-Ti, produced in the form of centrifugally cast tubes, were characterized by means of light optical microscopy, scanning electron microscopy (SEM) with secondary and backscattered electron imaging, and transmission electron microscopy (TEM) with energy-dispersive spectroscopy (EDS) and selected area diffraction. A complete description of the phases present in the as-cast, welded, and aged condition was made as a function of the modifying elements. The chromium carbide stoichiometry, secondary precipitation, NbC instability at elevated temperatures, the G-phase transformation, and the effect of Ti on this reaction are discussed. It is indicated that partial transformation of G-phase in the alloy modified with Ti is one of the explanations for the superior creep properties observed in this material.

• OSTI ID: 20748674
• Journal Information: Materials Characterization, Journal Name: Materials Characterization Journal Issue: 3 Vol. 49; ISSN 1044-5803; ISSN MACHEX
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
AGING
CHROMIUM CARBIDES
CREEP
DIFFRACTION
FURNACES
INSTABILITY
NIOBIUM CARBIDES
OPTICAL MICROSCOPY
PHASE TRANSFORMATIONS
PRECIPITATION
SCANNING ELECTRON MICROSCOPY
SPECTROSCOPY
STEELS
STOICHIOMETRY
TRANSMISSION ELECTRON MICROSCOPY
TUBES