Microstructural Stability During Creep Exposure of 9Cr-1Mo Steel Treated at Different Normalization Temperatures

Journal Article · Wed May 15 04:00:00 EDT 2019 · Journal of Materials Engineering and Performance

DOI:https://doi.org/10.1007/S11665-019-04074-3· OSTI ID:22970776

Chatterjee, Arya ^[1]; Modak, P. ^[2]; Barat, K. ^[3]; Chakrabarti, D.; Mitra, R. ^[2]

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1. Brown University, School of Engineering (United States)
2. Indian Institute of Technology Kharagpur, Department of Metallurgical and Materials Engineering (India)
3. National Aerospace Laboratories (NAL-CSIR) (India)

A modified 9Cr-1Mo steel has been exposed to three separate austenitization temperatures, i.e., at 950, 1025, and 1100 °C for normalization. After subsequent tempering at 750 °C, the normalized and tempered samples were creep-tested at temperatures of 550, 600, and 650 °C. The creep strength of the investigated samples was evaluated in terms of minimum creep strain rate and time to rupture. The effects of microstructure, precipitate and boundary misorientation on the creep behavior of the samples have been studied with TEM and EBSD analyses. Further, the evolution of crystallographic texture after creep tests has also been studied. The presence of an intermediate size of martensitic microstructural units (i.e., prior-austenite grain, martensitic packets, etc.) and combination of fine coherent and incoherent Nb(C,N) precipitates has provided superior creep strength for the samples normalized at 1025 °C, when these are subsequently subjected to low-temperature (i.e., 550 °C) and high-temperature (i.e., 650 °C) creep tests, as compared to other conditions of normalizing heat treatment.

• OSTI ID: 22970776
• Journal Information: Journal of Materials Engineering and Performance, Journal Name: Journal of Materials Engineering and Performance Journal Issue: 5 Vol. 28; ISSN 1059-9495; ISSN JMEPEG
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CREEP
ELECTRON DIFFRACTION
MARTENSITIC STEELS
MICROSTRUCTURE
PRECIPITATION
STRAIN RATE
TEMPERING