SYMPOSIA PAPER Published: 01 January 1999
STP15758S

Direct Observation of the Residual Plastic Deformation Caused by a Single Tensile Overload

Source

The fatigue crack growth behavior following single tensile overloads at high stress intensity ranges in a cold-rolled austenitic steel has been studied experimentally. After tensile overloads, fatigue cracks initially accelerate, followed by significant retardation, before the growth rates return to their baseline level. The initial acceleration was attributed to an immediate reduction in near-tip closure. Scanning electron micrography and stereophotogrammetric reconstruction of the fracture surface were applied to study the residual plastic deformation caused by a single tensile overload in the mid-thickness of the specimen. The measured residual opening displacement of the crack as a function of the overload is presented and compared with simple estimations. Also, free specimen surface observations of the residual plastic deformation and crack growth rate were performed. In the midsection of the specimens the striation spacing-length, i.e., the microscopic growth rates, were measured before and after the applied overload. It will be shown that the measured plasticity-induced wedges from the single overload and the observed propagation behavior support the significance of the concept of crack closure.

Author Information

Bichler, C
Erich-Schmid-Instutut für Festkörperphysik der Österreichischen Akademie der Wissenschaften, Leoben, Austria
Pippan, R
Erich-Schmid-Instutut für Festkörperphysik der Österreichischen Akademie der Wissenschaften, Leoben, Austria
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Details
Developed by Committee: E08
Pages: 191–206
DOI: 10.1520/STP15758S
ISBN-EB: 978-0-8031-5397-4
ISBN-13: 978-0-8031-2611-4