ALLIAGES D'ACIERS FERRITIQUES AYANT UNE BONNE RESISTANCE AU FLUAGE ET A L'OXYDATION

L'INVENTION CONCERNE UN ACIER FERRITIQUE AYANT UNE RESISTANCE AMELIOREE AU FLUAGE ET A L'OXYDATION.L'ACIER SELON L'INVENTION COMPREND ESSENTIELLEMENT EN POIDS, ENVIRON 0,01 A 0,06 DE CARBONE, ENVIRON 1 AU MAXIMUM DE MANGANESE, ENVIRON 2 AU MAXIMUM DE SILICIUM, ENVIRON 1 A 20 DE CHROME, ENVIRON 0,5 AU MAXIMUM DE NICKEL, ENVIRON 0,5 A 2 D'ALUMINIUM, ENVIRON 0,01 A 0,05 D'AZOTE, 1,0 AU MAXIMUM DE TITANE, LA TENEUR MINIMALE EN TITANE REPRESENTANT QUATRE FOIS LA TENEUR EN CARBONE PLUS 3,5FOIS LA TENEUR EN AZOTE, ENVIRON 0,1 A 1,0 DE NIOBIUM, LA SOMME TOTALE DU TITANE ET DU NIOBIUM NE DEPASSANT PAS ENVIRON 1,2, LE RESTE ETANT ESSENTIELLEMENT CONSTITUE DE FER.APPLICATION: FEUILLARDS ET TOLES POUR ARTICLES DESTINES A DES TEMPERATURES DE SERVICE ELEVEES. A ferritic steel having improved creep or sag resistance and oxidation resistance at temperatures ranging from about 732 DEG to 1093 DEG C. after a final anneal at 1010 DEG to 1120 DEG C., together with good weldability, the steel consisting essentially of, by weight percent, from about 0.01% to 0.06% carbon, about 1% maximum manganese, about 2% maximum silicon, about 1% to about 20% chromium, about 0.5% maximum nickel, about 0.5% to 2% aluminum, about 0.1% to 0.05% nitrogen, 1.0% maximum titanium, with a minimum titanium content of 4 times the percent carbon plus 3.5 times the percent nitrogen, about 0.1% to 1.0% columbium, with the sum total of titanium plus columbium not exceeding about 1.2%, and remainder essentially iron. In the form of cold reduced strip and sheet stock the steel has particular utility in motor vehicle components.