SEM stereo-section fractography observations. Final report
Cleavage initiation in engineering materials is governed by local microstructural inhomogeneities. These features are often the principal reason for the large scatter evident in fracture toughness measurements which, in extreme cases, can mask the fundamental relationship between cracking resistance and global material properties. The SEM stereo-section fractography (SSF) technique can be used to carefully evaluate these local inhomogeneities through simultaneous observation of both the fracture surface and the underlying microstructure. By sectioning the fracture surface close to the cleavage initiation site (within 10 microns), and perpendicular to both the fracture surface and the pre crack front, a direct correspondence between initiation and the local microstructure can be established. Information obtained from this technique can provide quantitative input about important, local microstructural features which can then be used to calibrate or create realistic micromechanical models. A compendium of SSF results is presented herein for cleavage cracking in disparate materials (A533B steel plates, MIL-70S multi-pass weldments, and Ti6A14V forgings), under various testing conditions. In each case, the SSF technique was able to unambiguously identify the dominant, local features which triggered cleavage initiation.
- Research Organization:
- Naval Surface Warfare Center, Carderock Div., Bethesda, MD (United States); Univ. of Maryland, College Park, MD (United States)
- OSTI ID:
- 658767
- Report Number(s):
- AD-A-349891/XAB; NSWCCRD-TR-61-97/10; TRN: 82540496
- Resource Relation:
- Other Information: PBD: May 1998
- Country of Publication:
- United States
- Language:
- English
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