SYMPOSIA PAPER Published: 01 August 2022
STP163820210046

Evaluation of Strain-Induced Artifacts in Crack Length Measurements via the Direct Current Potential Difference Technique

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The influence of strain on the efficacy of the direct current potential difference (dcPD) technique to detect crack extension at low stress intensities pertinent to environment-assisted cracking experiments was assessed via a series of mechanical experiments on smooth tension, notched tension, and single-edge-notched tension specimens of Monel K-500. Results demonstrated that both crack tip plasticity-induced changes in material resistivity and geometric contraction of the specimen cross-section contributed to the strain-induced dcPD-measured crack extension. However, the relative contributions of these two factors varied, with localized plasticity and geometric contraction providing the primary contribution to this “false” crack extension at low and high stress intensities, respectively. The net section stress corresponding to the proportional limit was observed to be a consistent, conservative metric to identify the transition between these governing influences across all tested geometries. The implications of these results in the context of their application to subcritical cracking experiments are discussed.

Author Information

Harris, Zachary, D.
Dept. of Materials Science and Engineering, University of Virginia, Charlottesville, VA, US
Burns, James, T.
Dept. of Materials Science and Engineering, University of Virginia, Charlottesville, VA, US
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Pages: 138–159
DOI: 10.1520/STP163820210046
ISBN-EB: 978-0-8031-7724-6
ISBN-13: 978-0-8031-7723-9