Ferritic stainless steels are classified in the 400 series, usually with 10% to 30% chromium content, and are often chosen for their excellent corrosion resistance and elevated temperature oxidation resistance. With greater strength than carbon steels, ferritics provide an advantage in many applications where thinner materials and reduced weight are necessary, such as automotive emission control systems. They are nonhardenable by heat treating and are always magnetic. Typical applications for ferritic stainless steels include petrochemical, automotive exhaust systems and trim, heat exchangers, furnaces, appliances and food equipment etc.