Cleavage fracture in bainitic and martensitic microstructures
This paper addresses the mechanisms of cleavage fracture in the pressure-vessel steel A533B. Microstructures of single bainite microstructures exhibit a higher propensity for brittle cleavage fracture than do those of auto-tempered martensites. The K{sub 1c} values of mixed microstructures are determined by the statistical distribution of the two phases and the range of the values is bounded by limits set by those for the single-phase microstructures. The results are explained in terms of the RKR model, which involves a local cleavage stress {sigma}*{sub F} and a distance ahead of the macrocrack tip, X, as two critical parameters. It is found that the carbides or carbide colonies act as critical microcrack nuclei, and hence play a key role in determining the fracture toughness, although packet boundaries in bainite may give rise to pop-in arrests in displacement-controlled tests.
- Research Organization:
- Univ. of Birmingham (GB)
- OSTI ID:
- 20000491
- Journal Information:
- Acta Materialia, Journal Name: Acta Materialia Journal Issue: 12 Vol. 47; ISSN 1359-6454; ISSN ACMAFD
- Country of Publication:
- United States
- Language:
- English
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