Effect of absorbed nitrogen on the microstructure and core loss property of non-oriented electrical steel (Note)

摘要

The study showed that absorption of nitrogen had taken place during decaburization of cold rolled coils of non-oriented electrical steel. Actual quantity of absorbed nitrogen varied with variation in decarburizing conditions. When the quantity of absorbed nitrogen was more than 150ppm, bulk of the nitrogen was concentrated near the surfaces of the coils. This nitrogen combined with solute aluminum to form fine A1N particles. These A1N particles were effective in pinning down the grain growth during annealing of de-carburized coils and thereby resulted in the formation of fine ferrite grains near the surface. However, when quantity of absorbed nitrogen was less than 100ppm, finer ferrite grains were not form near the surfaces. A strong relationship was developed between nitrogen content and core loss value of non-oriented electrical steel. The relationship showed that the nitrogen content should be restricted to below 150ppm to achieve a core loss value of 4.0 watt/kg in non-oriented electrical steel with silicon content of 2.7 percent and aluminum content of 0.20 percent.