Type 409 (UNS S40900/1.4512)
- Offers economical corrosion resistance and good formability
- Offers improved corrosion resistance over carbon steel
- It has an added titanium content, which stabilizes the steels
- The titanium also prevents the formation of chromium carbides during welding
Description
Stainless steel type 409 is a highly useful chromium alloy. It is the cheapest type of stainless steel. They are typically ferritic alloys (iron/chromium only) and are used for automobile exhausts. Type 409 is also adaptable to resistance spot and seam welding.
Steel 409 Ultra Form stainless steel, for instance, provides an excellent combination of improved forming, ridging and roping. These qualities are obtainable with precise control of chemistry and thermomechanical processing starting from melting to finishing.
Common Names: Chromium steel
Executive Standards:
- DIN 1.4512
- JIS SUH 409
- S. 409 S 17
- ASME SA268
- ASTM A176
- ASTM A268
- UNS S40900
Chemical Properties:
The chemical properties of stainless steel type 409 are presented in the table shown below.
| Element | Content (%) | |
| Carbon | (C) | 0.03 max. |
| Manganese | (Mn) | 1.00 max. |
| Phosphorus | (P) | 0.040 max. |
| Sulfur | (S) | 0.02 max. |
| Silicon | (Si) | 1.00 max. |
| Chromium | (Cr) | 10.50 – 11.70 |
| Nickel | (Ni) | 0.50 max. |
| Nitrogen | (N) | 0.03 max. |
| Titanium | (Ti) | 8(C+N) min. 0.15 – 0.50 |
Mechanical Properties:
The mechanical properties of the annealed grade 409 stainless steel are shown below
| Properties | Value | Condition |
| T (°C) | ||
| Density (×1000 kg/m3) | 7.8 | 25 |
| Poisson’s Ratio | 0.27-0.30 | 25 |
| Elastic Modulus (GPa) | 190-210 | 25 |
| Tensile Strength (Mpa) | 450 | 25 |
| Yield Strength (Mpa) | 240 | |
| Elongation (%) | 25 | |
| Reduction in Area (%) | ||
| Hardness (HRB) | 80 (max) | 25 |
Physical Properties:
The physical property of grade 409 stainless steel is shown below.
| Property
|
Value
|
| Density, lbs./in.3 (g/cm3) | 0.28 (7.8) |
| Specific Electrical Resistance (μΩ x cm) | 60.0 |
| Modulus of Elasticity in Tension at room temperature psi. (MPa) | 30.2 x 106
(20.8 x 104) |
Key Features:
- It offers economical corrosion resistance and good formability.
- Ductility can be improved by annealing after welding at temperatures of 760 to 815°C
Product Forms Available:
Forming involves roll forming, stretch bending, deep drawing, and pressing. It can be produced in different thickness for improved toughness and weldability. The surface finish of Type 409 stainless can also be enhanced by annealing and pickling after rolling.
Applications:
- Stainless Steel Type 409 alloy provides good oxidation and corrosion resistance, which is why they are used for automotive and non-automotive exhaust.
- Can be used in automotive and truck exhaust systems, tubular manifolds, agricultural spreaders, gas turbine, heat exchangers and fuel filters.
Possible Alternative Grades:
304, 430 or 439 grades stainless steel
FAQs
- What is the strength of stainless steel 409 resistance to corrosion?
409 has good oxidation resistance, but lower corrosion resistance due to the chromium content. 409 is not as corrosion resistant as grades like 304, 430 or 439. It is, however, 409 far more superior to mild carbon steel.
- Is 409 steel resistant to heat?
1450 °F (789 °C) is considered the practical upper-temperature oxidation service limit, but it is capable of brief excursions above 1600 °F (871 °C).
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