A high precision magnetostriction tester was developed for 100 x 500 mm conventional GO and HiB electrical steel samples. Length changes were measured by means of a laser displacement meter, having a detection limit of +/-10 nm, corresponding to Delta l/l = 1.5 x 10(-8) in relative measure to the magnetised length of I = 470 mm, The AC characteristic was quantified by the peak-to-peak magnetostriction lambda(B)(p-p) vs, induction curves. For a simple characterisation of the induction dependence of DC magnetostriction three new parameters are proposed, The first one is the maximum value of magnetostriction, defined as lambda(s)(B) = lim lambda((B-->Bs)), when the induction tends to the saturation. The second one is the slope of the curve at the inflection point, d/d B{lambda(B)}(max), characterising the highest speed of sign change of magnetostriction. The third one is the zero intercept point of the slope line - drawn to the point of inflection - on the X axis, the B-0 = B-m(lambda = 0). The results obtained on HiB 0.30 mm thick samples have confirmed a straight syntony between the above defined DC and AC magnetostrictive characterisation, which was previously demonstrated using the DC technique, referring to the DC measurement at opened magnetic circuit arrangement.
