The use of stainless steels, mainly ferritic stainless steels, is improving the service life of automotive exhaust components. In this paper, the development, the current application and the main properties of ferritic stainless steels produced by Acesita for automotive exhaust systems in Brazil are described. Acesita has developed specific stabilised ferritic grades both for the upstream part of the exhaust line (manifold, down-pipe, converter shell), where temperatures can reach 1100 deg C, and for the downstream part (muffler, resonator, tubes) where the major degradation problems involve corrosion caused by condensation on the internal parts. A new AISI 409, with low carbon and nitrogen, has been recently developed for deep drawing applications. Acesita is also producing nowadays grades with higher chromium contents like AISI 441, AISI 439 and AISI 434, that beyond offering the advantage of lower costs than austenitic grades, due to the lack of nickel, present higher mechanical properties and a better resistance to corrosion and oxidation than covered carbon steels. The good properties at high temperature of the ferritic stainless steels of type 441, such as better resistance to creep and to cyclical oxidation, results in to increasing of the consumption of the stainless steels in the exhaust system, with competitive advantages in the automotive industry as cost level as well of performance. The new grades 439 and 434 give important improvement to increase the useful life of the components of the cold part of the exhaust system, with lower cost in relation to the 304 grade and with better corrosion resistance in relation to the 409 grade. (VDEh)
Development of ferritic stainless steels for automotive exhaust systems
Entwicklung ferritischer nichtrostender Stähle für Auspuffsysteme von Kraftfahrzeugen
2002
4 Seiten, 8 Bilder, 4 Tabellen
Conference paper
English
Fahrzeugbauteil , Fahrzeugausrüstung , Abgasschalldämpfer , Abgasanlage , ferritischer nichtrostender Stahl , Werkstoffwahl , mechanische Eigenschaft , Streckgrenze , Dehnung , Korrosionsbeständigkeit , kohlenstoffarmer Stahl , R-Wert , Tiefziehstahl , Depassivierung , Chrom-Molybdän-Stahl , Chrom-Titan-Stahl
Ferritic stainless steels development and localization for automotive exhaust system
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