Ferritic Stainless Steels
Summary of Physical & Chemical Properties
While cost effective and containing the lowest quantity of chromium of the stainless grades, 409 offers the minimum in corrosion resistance with good weldability and formability. With additions of Titanium and very low carbon content, carbide precipitation is kept to a minimum during welding. This grade is not recommended where cosmetic appearance is critical and surface corrosion can occur in mild corrosive environments. Applications include heat exchanger tubes, tubular manifolds, muffler components and automotive and truck exhaust systems.
Increased levels of chromium and carbon provide this grade of ferritic stainless with better corrosion resistance and oxidation resistance while sacrificing weldability and formability. With higher carbon and no additions of stabilizing elements such as Titanium, care must be taken when welding 430 stainless steel. Applications include kitchen appliance components, gutters and downspouts, furnace combustion chambers and gas burner tubes.
The addition of Titanium to this grade as a carbon stabilizer combined with lower carbon levels makes it a more weldable and formable grade than that of the 430 stainless. The higher chromium content, between 17% and 19%, contributes to a superior high temperature corrosion resistance in various oxidizing environments, when compared to that of the 409 grade. 439 stainless is a good choice for automotive exhaust applications such as down pipes and tubular manifolds requiring good corrosion resistance in the cycling, higher temperature ranges.
This grade of ferritic stainless steel exhibits good high temperature strength, exceeding that of the 409 and the 439 grades. Cyclic high temperature oxidation resistance is very good, while overall corrosion resistance is similar to that of the 18% chromium, ferritic grades. 441 stainless steel is used in automotive and truck applications, such as exhaust manifolds and catalytic converter shells.
UNS S41003 / F12N (1.4003)
Known for toughness and abrasion resistance this grade of stainless is classified as a lower cost ferritic grade for structural applications. Corrosion resistance is better than that of standard structural steel, painted or unpainted, and good weldability and formability by standard processes is typically experienced. Applications include railroad carriages, shipping containers, conveyors, storage tanks, and passenger coach frames.