Ferritic Stainless Steels
Acier Alloys India Pvt. Ltd. INDIA PRODUCED VARIOUS STAINLESS STEEL PRODUCTS OF DIFFERENT GRADES, FERRITIC STAINLESS STEEL IS ONE OF THEM i.e AISI 400 SERIES GRADE.
Ferritic stainless steels are generally classified in the 400 series.These are nickel-free stainless steels which contain varying chromium content of 12- 18%, but a lower carbon content than the martensitic. A special heat resistant ferritic grade contains 26% Cr.The most common specifications are 430, 409 and weldable 12% Cr steels.
​
They are usually chosen for their excellent corrosion resistance and oxidation resistance at elevated temperature.Having greater strength than carbon steels, ferritic steels provide an advantage in many applications where thinner materials and reduced weight are necessary, such as automotive emission control systems. They are always magnetic and non hardenable by heat treating.
CORROSION RESISTANCE
Ferritic stainless steels exhibits good to excellent corrosion resistance depending on the chemical composition of the specific grade. Corrosion resistance is basically determined by the chromium content. Steels with molybdenum additions have improved pitting corrosion resistance. Ferritic grades are resistant to chloride stress corrosion cracking.
After certain high temperature exposures, the unstabilized ferritic grades can be susceptible to intergranular corrosion, including welding. A post-weld heat treatment and a stabilized grade is recommended for applications that require welding.
The commonly used grades are 409,430 etc.
WELDABILITY
Some restrictions are imposed on welding due to the metallurgical structure of the ferritic grades. In the heat affected zone, the unstabilized ferritic grades can form martensite leading to a loss of ductility. The grades which are stabilized with titanium or niobium have improved ductility in the as-welded condition.Poor weldability generally limits their applications as welded components to thin gauge material. Welded joints can exhibit low ductility and toughness due to grain growth, especially in heavy sections. Post-weld heat treatments will generally improve the ductility of weld zones.
APPLICATIONS
Ferritic stainless steels are used in a wide range of applications, including petrochemical industry, automotive exhaust systems and trim, heat exchangers, kitchenware, furnaces, dishwasher, food equipment & hot end exhaust system etc.
FORMABILITY
Ferritic stainless steels exhibits low formability.
GRADE 409 AND 409Ti
Used in an Automotive exhaust, Catalytic converter systems, Mufflers, Welded applications etc.
430 AND 430 F
(STANDARD GRADES)
Interior architectural components, clothes dryer liners, stove and automotive trim, dishwasher, Fasteners, Gears, Shafts & Pinions etc.
GRADE 446
Used for X-ray tube bases, Boiler baffles, Oil burner components, Annealing boxes, Industrial mufflers, Surface condensers, Kiln linings, Glass molds, Furnace parts, Water piping system etc.
