Ye. Wu et Cr. Yu, NONDESTRUCTIVE EVALUATION OF PLASTIC-DEFORMATION IN AA6061 ALUMINUM-ALLOY BY ELECTROMAGNETIC DISCHARGE IMAGE, Theoretical and applied fracture mechanics, 28(2), 1997, pp. 157-164
The electromagnetic discharge imaging (EDI) technique is combined with
image analysis methods and used as a nondestructive method to evaluat
e the amount of plastic deformation of AA6061 aluminum alloy. Various
amounts of plastic deformation was introduced mechanically by cold rol
ling on specimens having identical surface conditions to the specimen.
Since the EDI discharge characteristics and intensity are affected by
plastic deformation, the results can be used as a correlation. It is
shown that the EDI discharge intensity increases with increasing rolli
ng ratio up to 25% and reaches a saturation limit, beyond which the di
scharge intensity is inversely proportional to the rolling ratio. Sinc
e the changes of the internal energy and the electrical properties of
the specimen caused by cold rolling has opposing effects on the EDI di
scharge intensity. That would eventually be saturated. Further analysi
s shows that the high intensity region of EDI discharge pattern is inc
reased from 0-10% rolling ratio and then from 30% and up. As the AC fr
equency increased, the discharge intensity becomes proportional to the
increase rolling ratio. (C) 1997 Elsevier Science Ltd.