Crack-Growth Resistance Characteristics of High-Strength Sheet Alloys.
NAVAL RESEARCH LAB WASHINGTON D C
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Crack propagation in a metal sheet is impeded by the inherent resistance to fracture of the alloy. This resistance is manifested by the requirement that crack growth will occur only under a rising load up to an instability load at which unstable fracture commences. If the fracture resistance curve which designates the load-crack extension relationship to instability has a unique shape for each material and is independent of most specimen dimensions, it can be a valuable tool in failure-safe design. The fracture resistance curves R-curves have been obtained for six high-strength sheet alloys which fractured under elastic loads. The influence of three specimen geometric variables and yield strength on the shape of the R-curve and the critical stress-intensity factor K sub c was investigated. On several alloys a comparison was made between the R-curve and K sub c value generated with a center-cracked tension CCT specimen and data derived from a crack-line loaded CLL specimen used at Armco Steel Corporation. Author
- Metallurgy and Metallography