Patent ID: 7998237

Claim:
Method for producing steel products ( 1 ) with optimum surface quality of an ultralow carbon, high-strength and/or stainless steel grade, comprising the steps of: melting ( 2 ) the steel and treating the steel in a ladle metallurgy installation ( 3 ); subsequently continuously casting the steel ( 4 ) into a thin slab ( 5 a ) in a continuous casting mold ( 14 ), partially deforming, cutting the slab into partial strand lengths ( 15 ), descaling ( 28 ), heating to rolling temperature and homogenizing in a soaking furnace ( 16 ), descaling again and rolling in a finishing mill ( 6 a ), coiling in a first coiling station ( 20 ) immediately downstream of a last finishing stand ( 19 ) or, alternatively, downstream of a cooling line ( 21 ), and adjusting a final microstructure ( 9 ) in a cooling line ( 21 ) according to the desired grade of steel by cooling on a runout table ( 22 ), and finish-coiling the rolled product ( 1 a ) in a second coiling station; wherein said step of melting the steel and treating the steel includes providing a system capable of carrying out a plurality of process routes for producing molten steel including the following routes: (a) producing the molten steel ( 1 b ) in a melting installation ( 2 a ) which is not a steelworks converter, and treating in a vacuum degassing system ( 27 ) and in a ladle furnace ( 25 ), and (b) melting in an electric arc furnace ( 2 b ) or in a two vessel electric arc furnace, and treating in a ladle furnace ( 25 ) with an electrode system ( 31 ) and in a vacuum degassing system, and (c) melting in an electric arc furnace installation ( 35 ) or a two vessel electric arc furnace ( 30 ) capable of a two stage process or an individual furnace vessel ( 30 ), and treating in the ladle furnace ( 25 ) and in a differential-pressure vacuum degassing system ( 43 ), and (d) melting in an electric arc furnace ( 2 b ) with additions of alloying materials ( 26 ), and treating by a partial-quantity degassing in the ladle furnace ( 25 ), or a vacuum degassing system ( 27 ) and a ladle degassing ( 27 ); and selecting a process route for producing the molten steel from the process routes (a) through (d) to achieve a desired final microstructure ( 9 ).