Type 409 is:

Ferritic: An alloy containing a minimum of 10.5% chromium. It is a relatively inexpensive stainless steel that provides better corrosion and oxidation resistance than carbon steel. It performs well in dry air, less so in a corrosive environment. This material is easy to form and often used in non-cosmetic applications. Used in a variety of applications: Grade 409 was designed primarily for the automotive industry, in particular for automotive exhaust systems. Over the years it has been used in many other consumer and industrial products and applications such as agricultural spreaders, caskets, catalytic converters, exhaust pipes, fuel filters, heat exchangers, industrial exhaust systems, mufflers and tail pipes. Able to be processed in many ways: Metal processors and fabricators stamp, form, draw, bend, cut and weld alloy 409 to produce various parts. It is ductile and does not appreciably harden by cold working. Available in many variants: Different levels of niobium and titanium used for stabilization define the different variants of this alloy. Orders for type 409 (UNS S40900) can be filled with any of the ASTM variations unless the customer specifies a particular UNS designation.

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