Fatigue and fracture of porous steels and Cu-infiltrated porous steels
- Case Western Reserve Univ., Cleveland, OH (United States)
The effects of Cu infiltration on the monotonic fracture resistance and fatigue crack growth behavior of a powder metallurgy (P/M) processed, porous plain carbon steel were examined after systematically changing the matrix strength via heat treatment. After austenization and quenching, three tempering temperatures were chosen (177 C, 428 C, and 704 C) to vary the strength level and steel microstructure. The reductions in strength which occurred after tempering at the highest temperature were accompanied by the coarsening of carbides in the tempered martensitic steel matrix, as confirmed by optical microscopy and by microhardness measurements of the steel. Each steel-Cu composite, containing approximately 10 vol pct infiltrated Cu, had superior fracture toughness and fatigue properties compared to the porous matrix material given the same heat treatment. Although the heat treatments given did not significantly change the fatigue behavior of the porous steel specimens, the fatigue curves (da/dN vs {Delta}K) and fracture properties were distinctly different for the steel-Cu composites given the same three heat treatments. The fracture toughness (K{sub IC} and J{sub IC}), tearing modulus, and {Delta}K{sub TH} values for the composites were highest after tempering at 704 C and lowest after tempering at 177 C. In addition, the fracture morphology of both the fracture and fatigue specimens was affected by changes in strength level, toughness, and {Delta}K. These fractographic features in fatigue and overload are rationalized by comparing the size of the plastic zone to the microstructural scale in the composite.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 315938
- Report Number(s):
- CONF-970980-; ISSN 1073-5623; TRN: IM9908%%18
- Journal Information:
- Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science, Vol. 30A, Issue 2; Conference: Materials Week `97, Indianapolis, IN (United States), 14-18 Sep 1997; Other Information: PBD: Feb 1999
- Country of Publication:
- United States
- Language:
- English
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