Patent ID: 6276437
Filing Date: 2001-08-21
Classification: B21B,B22D

Abstract:
A method for the manufacture of formable steel strip comprising the steps of:forming in a mould of a continuous casting machine liquid steel into a thin slab having a thickness of less than 150 mm, homogenizing in a homogenizing furnace and rolling the slab in the austenitic region using the casting heat to obtain an intermediate slab using the casting heat,optionally cooling the intermediate slab to a temperature where a substantial portion of the steel is transformed into the ferritic region, and rolling said intermediate slab to the strip either in the austenitic or ferritic region,wherein the liquid steel is fed from a ladle into a first atmospheric chamber of a vacuum tundish also comprising a second chamber hydraulically connected by a conduit to the first chamber in which second chamber a low pressure is preserved, the steel passes from the first chamber to the second chamber, and the steel is conveyed from the second, low pressure or vacuum chamber, through an exit port therein into the mould, the conduit comprising a valve means;introducing a purging gas via purging means into the liquid steel after the steel has entered the first chamber but before the steel entered the second chamber, andemploying the valve to regulate the passing of the liquid steel through the conduit between the first chamber and the second chamber, andwherein the purging means is operated in the vicinity of, or at, the valve means, and introduces the purging gas for rinsing the liquid steel.