Stainless steel 409 is a Ferritic steel. With applications that demand weldability and applications in exhaust systems of automobiles, 409 stainless steel is commonly considered as a chromium stainless steel. It good mechanical properties and high-temperature corrosion resistance.

Stainless steel 409 have excellent resistance to exhaust gas and atmospheric corrosion, superior to that of 410 martensitic grades with 12% chromium and 3CR12. However, the corrosion resistance is lower than that of grade 430 steels containing 17% chromium. The surface of Stainless steel 409 is liable to mild corrosion, which limits the usage of steels for decorative purposes.