Ferritic stainless steel 409

Type 409 stainless steel, a low cost ferritic stainless steel. Its dominant use is in vehicle exhaust systems, so much

so that it is often referred to as “muffler” grade.is especially useful for applications like automotive and truck exhaust systems, tubular manifolds, agricultural spreaders, gas turbine exhaust silencers, heat exchangers and fuel filters.

409 stainless grade combines the following characteristics:

• Basic corrosion and oxidation resistance
• Composition balanced for optimum formability
• Weldable only in thin sections due to fully ferritic structure
• Low cost and limited cost variation due to low alloy content

Automotive exhaust systems have to withstand aggressive conditions from high temperatures at the manifold end, sulphuric acid condensate and de-icing salt. Given the severity of these conditions, it can seem surprising that the 

11% Cr 409 grade has met the challenge for many years. Exhaust components are also required to be bent, expanded 

and pressed into all sorts of convoluted shapes. The ability of a ferritic steel to meet these formability requirements is

little short of amazing.

Chemical composition ( weight % )

• hot and cold rolled steel strip, coil, sheet and plate
• stainless steel welded tube