Patent ID: 7056398
Filing Date: 2006-06-06
Classification: C21D,C22C

Abstract:
1. A method for making a ferritic stainless steel sheet, comprising the steps of: hot-rolling a steel slab comprising about 0.01 percent by mass or less of carbon; about 1.0 percent by mass or less of silicon; about 1.5 percent by mass or less of manganese; about 11 to about 23 percent by mass of chromium; about 0.06 percent by mass or less of phosphorous; about 0.03 percent by mass or less of sulfur; about 1.0 percent by mass or less of aluminum; about 0.04 percent by mass of nitrogen; about 0.0005 to about 0.01 percent by mass of boron; 0.004 to 0.3 percent by mass of vanadium; about 0.8 percent by mass or less of niobium and/or about 1.0 percent by mass or less of titanium wherein 18≦Nb/(C+N)+2(Ti/(C+N))≦60; and the balance being iron and unavoidable impurities to form a hot-rolled sheet; annealing the hot-rolled sheet to form an annealed sheet; cold-rolling the annealed sheet either once or at least two times with intermediate annealing to form a cold-rolled sheet; finish-annealing and pickling the cold rolled sheet to form a pickled steel sheet containing crystal grains having an average crystal grain diameter of about 40 μm or less; and skin-pass rolling the pickled sheet with skin-pass rolls having a roughness of Ra of 0.05 to 1 μm at a reduction rate of 0.05 to 10% to obtain a sheet having an average surface roughness of about 0.3 μm or less.