SHEET FERRITE STAINLESS STEEL, METHOD OF ITS PRODUCTION AND ITS APPLICATION, ESPECIALLY IN EXHAUST SYSTEMS

摘要

1. Sheet ferritic stainless steel with a composition, wt. %: - trace amounts ≤С≤0.03%; - 0.2% ≤Mn≤1%; - 0.2% ≤Si≤1%; - trace amounts ≤S≤0.01%; - trace amounts ≤ P≤0.04%; - 15% ≤Cr≤22%; - trace amounts ≤Ni≤0.5%; - trace amounts ≤Mo≤2%; - trace amounts ≤Cu≤0.5%; - 0.160% ≤Ti≤1%; - 0.02% ≤Al≤1%; - 0.2% ≤Nb≤1%; - trace amounts ≤V≤0.2%; - 0.009% ≤N≤0.03%; preferably between 0.010% and 0.020%; - trace amounts ≤Co≤0.2%; - trace amounts ≤Sn≤0.05%; - rare earth elements (REE) ≤0.1%; - trace amounts ≤Zr≤0, 01%; - the remaining iron and inevitable impurities obtained during smelting, the content of Al and rare-earth elements (REE) satisfying the dependencies: Al + 30 × REE≥0.15%; and the percentage of Nb, C, N and Ti in percent satisfying the dependencies : 1 / [Nb + (7/4) × Ti-7 × (C + N)] ≤3; wherein said sheet has a completely recrystallized structure and an average ferrite grain size between 25 and 65 μm. 2. A method for the production of sheet ferritic stainless steel, characterized in that: - a steel is obtained having the aforementioned composition according to claim 1; - a billet is made from steel by casting; - the billet is brought to a temperature of more than 1000 ° C and less than 1250 ° C and then subjected hot rolling to obtain a hot-rolled sheet with a thickness of between 2.5 and 6 mm; said hot-rolled sheet is subjected to cold rolling at a temperature between room temperature and 300 ° C, performed in one stage or in several stages separated by intermediate annealing steps ; - perform the final annealing of the cold-rolled sheet at a temperature between 1000 and 1100 ° C for a period of time between 10 seconds and 3 minutes to obtain a fully recrystallized structure with average grain sizes between 25 and 65 microns. 3. A method for the production of sheet ferritic stainless steel, characterized in that: - receive steel having the composition according to claim 1; - from steel by casting