Analysis of the decarburization and aging processes in 2/sup 1///sub 4/ Cr--1 Mo steel
Specimens of 2/sup 1///sub 4/ Cr-1 Mo steel that had been decarburized in sodium or aged in an inert atmosphere for 26,500 h at 839/sup 0/K were metallurgically examined with optical and transmission electron microscopy. The carbide particle density of the decarburized and aged specimens was considerably less after 26,500 h than after 10,000 h, with the density in the aged specimen being considerably greater than that in the decarburized specimen. For the aged specimen, the density decrease was a result of Ostwald ripening, and the total amount of carbide was not noticeably affected. Decarburization, however, resulted in a gradient in carbide density, with the smallest density near the surface. Carbides were electrolytically extracted and identified by x-ray diffraction. From the before-test material, which was in the annealed condition and had a ferrite-pearlite microstructure, 1.4 wt percent carbide was obtained. This sample contained M/sub 3/C, M/sub 23/C/sub 6/, and M/sub 6/C, with M/sub 23/C/sub 6/ constituting the major portion. In the aged specimen, 2.3 wt percent of precipitate was extracted and contained 60 percent M/sub 6/C, the balance M/sub 23/C/sub 6/. The decarburized specimen contained two regions with different carbide contents. The first 20 percent of the 1.6 mm thick specimen yielded 1.3 wt percent precipitate, which contained 94 percent M/sub 6/C, the balance M/sub 23/C/sub 6/. The interior of the specimen contained 1.6 wt percent precipitate, 86 percent M/sub 6/C. (auth)
- Research Organization:
- Oak Ridge National Lab., TN
- OSTI ID:
- 7364480
- Journal Information:
- Metall. Trans., A; (United States), Journal Name: Metall. Trans., A; (United States) Vol. 6A; ISSN MTTAB
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360102* -- Metals & Alloys-- Structure & Phase Studies
AGING
ALLOYS
ANNEALING
CARBIDES
CARBON COMPOUNDS
CHEMICAL REACTIONS
CHROMIUM ALLOYS
CHROMIUM STEELS
CHROMIUM-MOLYBDENUM STEELS
COHERENT SCATTERING
CRYSTAL STRUCTURE
DECARBURIZATION
DIFFRACTION
ELECTRON MICROSCOPY
HARDENING
HEAT TREATMENTS
HIGH TEMPERATURE
INERT ATMOSPHERE
IRON ALLOYS
IRON BASE ALLOYS
MICROSCOPY
MICROSTRUCTURE
PRECIPITATION HARDENING
SCATTERING
STEELS
TIME DEPENDENCE
X-RAY DIFFRACTION