On the fatigue crack growth resistance of upper bainite-martensite in an AISI 4330 steel
- Defence Metallurgical Research Lab., Hyderabad (India)
- Wright-Patterson Air Force Base, OH (United States)
- Indian Inst. of Tech., Madras (India)
- Jawaharlal Nehru Centre for Advance Research, Bangalore (India)
Investigation on 4340 type low alloy high strength steels have shown that bainite-martensite mixed microstructures display, in certain cases, an improved combination of strength and toughness as compared to the behavior of these steels in the fully martensitic condition. The literature reveals that, in association with tempered martensite, lower bainite is the preferred form of bainite for improved mechanical behavior with about 25% by volume of lower bainite being an optimum proportion. On the other hand, the presence of upper bainite was seen to be detrimental. Contrary to these observations, the recent work on a vanadium containing steel corresponding to the AISI 4330 designation suggests that the presence of upper bainite in a mixed microstructure tempered at 473 K results in a significant improvement in toughness at the same strength level as that of the fully martensitic structure. Here the authors report in the same steel the fatigue crack growth behavior of upper bainite-martensite mixed structure. As was observed in regard to tensile properties and fracture toughness, the fatigue crack growth resistance of upper bainite-martensite mixed microstructure is shown to be superior by comparison with the behavior of the fully martensitic structure.
- OSTI ID:
- 6788116
- Journal Information:
- Scripta Metallurgica et Materialia; (United States), Vol. 28:10; ISSN 0956-716X
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
LOW ALLOY STEELS
MECHANICAL PROPERTIES
MICROSTRUCTURE
COMPARATIVE EVALUATIONS
CRACK PROPAGATION
EXPERIMENTAL DATA
FATIGUE
FRACTURE PROPERTIES
TENSILE PROPERTIES
ALLOYS
CRYSTAL STRUCTURE
DATA
EVALUATION
INFORMATION
IRON ALLOYS
IRON BASE ALLOYS
NUMERICAL DATA
STEELS
360103* - Metals & Alloys- Mechanical Properties
360102 - Metals & Alloys- Structure & Phase Studies