Improvements in quality at CST for ultra-low carbon steel slabs applied in automotive sheets

Abstract

After the commissioning of its vacuum degasser (RH-KTB) in 1998, Companhia Siderúrgica de Tubarão (CST) started the development of slabs to be applied as high value added products, such as ultra-low carbon steel grades (ULC) for automotive applications. For this purpose, it was necessary to promote the development of a quality design system, encompassing all stages of steel manufacturing and slab casting at CST, as well as the steps of finishing rolling and coating. This paper describes the methodology for development of ULC steels at CST together with the company Sollac-Lorraine emphasizing the interchange of technical information aiming the continuous improvement. In this way, the results of the end product surface inspection are correlated with the technical parameters of steel production, including the quality events of steel refining and casting, as well as the slab conditioning.