Optimal Control of Inclusions to Prevent “Sand-Hole” Surface Defects in Deep Cold-Drawn Battery Cups for Electrical Vehicles

Abstract

The present work was conducted to elucidate the influence of inclusionson surface quality of deep cold-drawn battery cups for electrical cars. The obtained results revealed that, to prevent the surface defects of sand-holes in battery cups in deep cold-drawing process, attentions should be paid to steelmaking and casting process for optimal control of inclusions. Because sand-holes were often caused by large Al₂O₃ clusters and CaO-Al₂O₃ particles. Most important, a worthy finding was that these inclusions were not safe when they were over 100 μm and bigger than 27 μm, respectively, which was important for process optimization. By reducing (FeO) contents in ladle slag and tundish covering flux to about 5% or lower, together with optimal fluid flow of molten steel in tundish, such large inclusions can be well decreased to prevent the occurrences of sand-holes in battery cups in industrial production.