Stainless Steel Grade AISI 409 | EN 1.4512 | DIN X2CrTi12

AISI 409 | EN 1.4512 | DIN X2CrTi12 - is a ferritic grade of stainless steel. Its chemical composition averages 11% chromium and 1% titanium. It is mainly used to produce sheets, strips and rods. AISI 409 has found its application mainly in the automotive industry and mechanical engineering.

AISI 409 has significantly improved corrosion resistance compared to mild carbon steel in many indoor and rural outdoor applications where chloride contamination is very low. When discoloration and surface rust are acceptable, it can often provide a reasonably long service life in many structures. Paint or protective coating may be applied for decorative purposes. Better material performance is usually achieved by adequate design, proper post-weld treatment and regular cleaning in use.

Ferritic stainless steel EN 1.4512 has excellent resistance to exhaust gases and atmospheric corrosion, exceeding the martensitic grade AISI 410 with 12% chromium and 0.75% nickel. However, its corrosion resistance is lower than that of AISI 430 steel containing 17% chromium. Its surface is subject to moderate corrosion, which still limits its use for decorative purposes.

AISI 409 | EN 1.4512 grade has greater wear resistance than unalloyed structural steels, especially in aggressive environments.

Due to the titanium content, the risk of sensitization of intercrystalline corrosion is significantly reduced compared to non-stabilized ferritic grades. This grade of steel can be used in the temperature range in which chromium carbides precipitate in non-stabilized ferritic grades. The maximum operating temperature in dry air is 600 °C. The presence of other corrosive compounds in a hot environment, such as water or sulfur compounds, can significantly reduce the maximum service temperature.

The steel exhibits good corrosion resistance in many halogen-free organic and inorganic solutions over a wide range of temperatures and concentrations. When exposed to acidic solutions of pH value, uniform corrosion is likely to occur at low temperatures.

In aqueous solutions containing halides, such as chlorides or bromides, pitting and crevice corrosion may occur depending on the halide concentration, temperature, pH, concentration of oxidizing compounds or crevice geometry. Even relatively low concentrations of halides may cause corrosion damage. The presence of corrosion-inhibiting or accelerating compounds, such as transition metal ions or organic compounds, may influence the corrosion behaviour of AISI 409.

Welding

It has good weldability and can be welded using conventional welding methods. Conventional welding methods such as MMA, MIG, MAG, TIG, SAW, LBW or RSW are applicable, except gas welding. Austenitic or ferritic fillers can be used. This grade of metal should be preheated to 150 to 260 °C before welding. Care should be taken when welding with minimal heat to prevent grain growth.

Cold processing

Forming AISI 409 is comparable to many high-quality carbon steels. It is well suited for standard cold forming operations such as bending, flanging and drawing. It is particularly suitable for deep drawing.

The steel is relatively easy to maintain. Compared to austenitic grades, it has a lower tendency to form edges, which gives a larger finishing window. Since machinability is comparable to that of low-alloy carbon steels, the same recommendations for tool selection, cutting speed, and cutting band feed apply.

Heat treatment

Annealing of the grade is carried out at a temperature of 790 to 900 °C with subsequent cooling in air. Does not harden.

Heat resistance

Resistant to scale formation at temperatures up to 675 °C continuously and up to 815 °C intermittently. These temperatures apply to specific operating conditions.

Mechanical properties

Where can this steel be used ?

- car exhaust pipes;
- catalytic converter systems;
- mufflers.