The generalization of catalytic exhaust systems in most industrialized countries has substantially modified the service conditions of the materials used for their construction. This resulted in a strong increase of the use of stainless steels. Type 409 (11 % Cr,Ti) provides acceptable service performance for many parts of car exhaust systems for temperatures up to 750 deg C. However, in specific cases such as higher temperatures, highly corrosive conditions, etc. austenitic stainless steels are also used, increasing the cost of the system. The study of hot end conditions in car exhaust systems has led to the development of 441 LI (W4509), a 18 Cr, 0,6 Nb, Ti ferritic steel offering an alternative to 321. Its high chromium content improves heat resistance up to 1000 deg C and niobium is added to increase its high temperature strength. The objective of the present work is the similar development of an economic alternative to austenitic stainless steels in the cold end of the system, where condensate corrosion and external corrosion are too severe for 409 LI or when the designer requires a longer life of components, at the lowest possible cost. The new alloy, 436 LI, is a 18 % Cr, 1,2 % Mo, 0,5 % Cu, Nb, Ti stabilized ferritic stainless steel and it is compared with other stainless steels in terms of corrosion resistance and costs.
Monitoraggio delle reali condizioni di lavoro di sistemi di scarico auto catalizzati: Sviluppo di prodotti inox taylor-made
Kontrolle der tatsächlichen Bedingungen im Auspuff von Katalysatorfahrzeugen: Entwicklung von speziell zugeschnittenen nichtrostenden Teilen
Monitoring of actual car catalytic systems in service conditions: A challenge for upgrading material properties
Metallurgia Italiana ; 90 , 1 ; 47-51
1998
5 Seiten, 6 Bilder, 7 Tabellen, 3 Quellen
Aufsatz (Zeitschrift)
Italienisch
Katalysator , Fahrzeug , Werkstoffwahl , austenitischer Stahl , ferritischer Stahl , Korrosionsbeständigkeit , Kondensieren , Chlorion , Versuchsdurchführung , Oxidation , Grenzformänderungskurve , Schweißbarkeit , Kosten , Preis (Handelswert) , Kondensat , Verarbeitbarkeit , Schalldämpfer , Chrom-Nickel-Stahl , Chrom-Titan-Stahl
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