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Peravudh Lowhaphandu John J. Lewandowski 《Metallurgical and Materials Transactions A》1999,30(2):325-334
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 austenitization 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 ΔK) and fracture properties were distinctly different for the steel-Cu composites given the same three heat treatments. The
fracture toughness (K
IC
and J
IC
), tearing modulus, and ΔK
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 ΔK. These fractographic features in fatigue and overload are rationalized by comparing the size of the plastic zone to the microstructural
scale in the composite.
This article is based on a presentation made in the symposium “Fatigue and Creep of Composite Materials” presented at the
TMS Fall Meeting in Indianapolis, Indiana, September 14–18, 1997, under the auspices of the TMS/ASM Composite Materials Committee. 相似文献
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