Effect of Aluminium Addition on the Magnetic Properties of a Semi-Processed Electrical Steel

Kleiner Marques Marra,Lívia Carneiro Marra,Vicente Tadeu Lopes Buono

doi:10.1590/1980-5373-mr-2015-0659

Abstract

Aluminum is often added to electrical steels since this element causes improvement of the magnetic properties. However the addition of aluminum is usually limited to 0.30 wt%1. Therefore, this work aimed at evaluating the influence of higher levels of aluminum in the magnetic properties of semi-processed steels. To accomplish this, four types of steel were produced in laboratory with different aluminum contents (0.10, 0.30, 0.60 and 1.0 wt%). Carbon, manganese and silicon concentrations were kept constant. It was observed that an increased aluminum content caused reduction of the magnetic core loss, especially of the eddy current component. However, the magnetic permeability virtually wasn't influenced by aluminum concentration.

Highlights

Grain non-oriented (GNO) electrical steel is employed mainly to the cores of electric generators and motors
Carbon, sulfur, nitrogen, and oxygen are commonly present in GNO steel in low concentration, and their presence is inherent to the steel production process
The increased aluminum content led to a steady rise of electrical resistivity

Summary

Introduction

Grain non-oriented (GNO) electrical steel is employed mainly to the cores of electric generators and motors. GNO steels are suitable for this application because of the small anisotropy of magnetic properties Within this class of materials, there is the semi-processed electrical steel, which is usually supplied as cold rolled sheet and, in this condition, has inadequate magnetic properties[2,3]. These properties are enhanced through heat treatments carried out by the fabricators of motors and generators, commonly denominated decarburization treatment. Carbon, sulfur, nitrogen, and oxygen are commonly present in GNO steel in low concentration, and their presence is inherent to the steel production process Such elements are very harmful to magnetic properties. The use of such elements should be made in a controlled manner, as, when in excess, they can reduce the saturation magnetic polarization

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Conclusion