Abstract
Galvanomagnetic stress assessment exploits the sensitivity of the Hall coefficient in conducting materials on elastic deformation that is measured by the galvanomagnetic gauge factor. Earlier investigations based on the so-called transverse galvanomagnetic potential difference method considered only the galvanomagnetic gauge factor for current flow parallel to the applied uniaxial stress. However, typical surface treatments, such as shot peening, produce essentially isotropic plane state of residual stress, which means that the effects of parallel and normal stress components are inherently summed for any direction of current flow. The outcome could be either enhancement of the sensitivity or almost complete cancellation. Both parallel and normal galvanomagnetic gauge factors were measured with directional contact sensing at 16 Hz as well as the average galvanomagnetic gauge factor with nondirectional inductive sensing at 260 kHz. These tests showed that the galvanomagnetic gauge factors of fully hardened IN718 exhibit favorable behavior for residual stress profiling in surfacetreated components because their values are the same ? = +2.7 within the estimated measurement uncertainty of ±0.1 for both parallel and normal stress orientations.
How to Cite:
Bodine, N. ., Nagy, P. B., Hassan, W. ., Bodine, N. ., Nagy, P. B. & Hassan, W. ., (2019) “Directional and nondirectional galvanomagnetic gauge factor measurements for residual stress assessment in IN718”, Review of Progress in Quantitative Nondestructive Evaluation .
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