Abstract

Recently developed high-frequency Hall coefficient and eddy current conductivity measurement techniques were used to characterize fully hardened shot-peened IN718 coupons of Almen 4A, 8A and 12A intensity in both as-peened and thermally relaxed state. The experimentally obtained Hall impedance and conductivity spectra were inverted using a dual-mode inversion technique into residual stress and cold work depth-profiles. It was found that the Hall impedance decreases in shot-peened IN718 with the magnitude of the change increasing with peening intensity and decreasing with thermal relaxation. In contrast, typical conductivity changes are an order of magnitude lower, but measurements on Almen 12A deviated from this trend due to lift-off issues caused by the curvature of the coupon. The inverted residual stress profiles before and after thermal relaxation clearly indicated a significant decrease in the compressive residual stress levels due to thermal relaxation. The inverted residual stress and cold work profiles were compared with XRD results. Although, the quantitative agreement leaves much to be desired at this point, the qualitative agreement is promising for future studies.

How to Cite:

Velicheti, D. ., Nagy, P. B. & Hassan, W. ., (2019) “Dual-mode galvanomagnetic characterization of shot-peened IN18 coupons”, Review of Progress in Quantitative Nondestructive Evaluation .