The use of magnetic field annealing on nodular cast iron for speaker cores

Abstract

This work presents the application of induced magnetic field during the heat treatment of Nodular Cast Iron to improve the magnetic permeability of this material in order to use it in speakers, as a lower cost alternative to the forged low carbon steel. Magnetic field annealing was carried out observing the performance of the initial magnetic permeability of the samples, and subsequently measured with field saturation equipment. The results were correlated with the data obtained from the use of the SAE 1020 steel, with the same conditions of use and laboratory tests. Metallographic and chemical composition analyses were carried out on the samples, and the correlation of these data with the magnetic properties. Results of this study show the possibility of using magnetic field annealing as a way to increase the permeability of a material with high carbon content as the nodular cast iron.