The new approach to the nondestructive evaluation of iron based material by observation of thickness deformations

Nondestructive evaluations of iron-based structural materials have been investigated by observing leakage flux distributions after saturation polarizations in strong fields and by observing thickness deformations with a Laser-CCD system from outside. The latter was found very useful and sensitive to detect the residual stresses in comparisons with those by leakage flux detections, especially for a stress range less than 1%.