Influence of long-term aging and superimposed creep stress on the microstructure of 2. 25Cr-1Mo steel

Journal Article · Mon Feb 01 00:00:00 EST 1993 · Metallurgical Transactions, A (Physical Metallurgy and Materials Science); (United States)

DOI:https://doi.org/10.1007/BF02657318· OSTI ID:6136480

Gope, N; Chatterjee, A; Mukherjee, T ^[1]; Sarma, D S ^[2]

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1. Tata Iron and Steel Co., Ltd., Jamshedpur (India)
2. Benaras Hindu Univ., Varanasi (India)

To understand the influence of high-temperature aging and superimposed creep stress on the microstructural variations in a 2.25Cr-1Mo steel, the shoulder and gage portions of the specimens subjected to stress-rupture tests at 540 C and 580 C have been studied by transmission electron microscopy. In the normalized and tempered condition, the steel exhibited a tempered bainitic structure and the carbides were present as M[sub 3]C globules, M[sub 2]C platelets, and M[sub 23]C[sub 6] rectangular parallelepipeds. Aging the steel at 540 C for 7022 hours or 17,946 hours resulted in considerable coarsening of M[sub 2]C and caused precipitation of M[sub 6]C carbides. The super-imposed creep stress enhanced the M[sub 2]C precipitation. The ferrite matrix exhibited some recovery in the specimens exposed for 17,946 hours. While M[sub 2]C platelets were observed in a few areas after 14,836 hours of aging at 580 C, this carbide was virtually nonexistent when a stress of 78 MPa was superimposed. Amounts of M[sub 23]C[sub 6] persisted throughout the tests at both 540 C and 580 C. The M[sub 6]C carbide became more predominant after long exposure at 580 C. The ferrite matrix recovered considerably in specimens subjected to creep stress at 580 C for 14,836 hours.

• OSTI ID: 6136480
• Journal Information: Metallurgical Transactions, A (Physical Metallurgy and Materials Science); (United States), Vol. 24:2; ISSN 0360-2133
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CHROMIUM-MOLYBDENUM STEELS
AGING
CREEP
MICROSTRUCTURE
CARBIDES
CHEMICAL COMPOSITION
CORRELATIONS
EXPERIMENTAL DATA
FERRITE
MECHANICAL TESTS
PRECIPITATION
RUPTURES
SHAPE
TEMPERATURE RANGE 0400-1000 K
TRANSMISSION ELECTRON MICROSCOPY
ALLOYS
CARBON ADDITIONS
CARBON COMPOUNDS
DATA
ELECTRON MICROSCOPY
FAILURES
INFORMATION
IRON ALLOYS
MATERIALS TESTING
MECHANICAL PROPERTIES
MICROSCOPY
NUMERICAL DATA
SEPARATION PROCESSES
TEMPERATURE RANGE
TESTING
360103* - Metals & Alloys- Mechanical Properties
360102 - Metals & Alloys- Structure & Phase Studies