Experimental Investigation of Magnetic Permeability Degradation Due to Welding in 80NI–Fe and 50NI–Fe Magnetic Shielding Alloys

Abstract

This experimental study investigates welding operation on two magnetic shielding materials (80Ni–Fe and 50Ni–Fe), and the results indicate that, especially at lower excitation amplitude and frequency (50 Hz), the permeability of the welded joints can be significantly lower, i.e., reduced by up to 80% from the original value. At a higher frequency (400 Hz), the apparent degradation is not as severe, mostly because the apparent permeability is significantly lower due to global eddy currents. If welds constitute only a small proportion of the overall volume of the shield, the equivalent permeability is affected proportionally to the reluctance of each part. Recommended annealing is unable to fully recover the initial permeability measured at lower frequencies, but it is beneficial in improving the permeability.