409L Stainless Steel Pipes 409 Stainless Steel
ASTM A268 409 409L 1.4512 stainless steel is an alloy designed principally for the automotive exhaust industry, although it has been used successfully in other industrial applications. It combines good elevated temperaturecorrosion resistance with medium strength, good formability and overall cost. 409L stainless steel is highly resistant to high temperatures, achievable engine and exhaust systems, and reduces the thickness of the exhaust system to reduce exhaust emissions. Low cost, good flexibility, high yield, easy replacement, and environmentally friendly new products.
409 Stainless Steel is a titanium stabilised ferritic stainless steel. Although regarded as a general-purpose chromium stainless steel the primary application for Grade 409 is automotive exhaust systems. Its applications are those where appearance is a secondary consideration to mechanical properties and corrosion resistance and where some weldability is required.
Type 409 is a ferritic stainless steel that has a good combination of heat resistance and corrosion resistance. Its titanium stabilized low nickel content provides for an economical metal to corrosion resistance and oxidation resistance .
More highly stabilised versions of 409 are useful where 409 has been proven marginal – these grades S40910, S40920 and S40930 are stabilised with titanium, niobium or both titanium and niobium. Used to automobile mufflers, catalytic converters, tailpipes, farm equipment, structural supports and hangers, transformer cases, diamond tread plate and shipping containers.
Magnetic Properties: 409 flat rolled stainless steel is magnetic and cannot be hardened by heat treatment. It can, however, be somewhat hardened by cold-working. Type 409 has great ductility and is suitable for use in deep draw applications. It is also easily formable.
Chemical Composition of ASTM A268 409 S40900 Grade and EN 10088-2 1.4512 1.4516 Stainless Steel
| Grade | – | C | Mn | Si | P | S | Cr | Ni | Ti |
| A268 409 | min. max. | – 0.08 | – 1.00 | – 1.00 | – 0.045 | – 0.030 | 10.5 11.7 | – 0.50 | 6×C-0.75 |
| TP409L | min. max. | – 0.035 | – 1.00 | – 1.00 | – 0.045 | – 0.030 | 10.5 11.7 | – 0.50 | 6×C-0.75 |
| 1.4516 | min. max. | – 0.08 | – 1.50 | – 0.70 | – 0.040 | – 0.015 | 10.5 12.5 | 0.50-1.50 | 0.05-0.35 |
| 1.4512 | min. max. | – 0.030 | – 1.00 | – 1.00 | – 0.040 | – 0.015 | 10.5 12.5 | – 0.50 | 6×(C+N)-0.65 |
Mechanical properties of ASTM A268 409 Grade and EN 10088-2 1.4512 stainless steel
| Grade | Tensile Strength | Yield Strength 0.2% Proof | Elongation | Hardness | Hardness |
| Grade | ksi(MPa) min | ksi (MPa) min | (% in 50mm) min | Rockwell B (HR B) max | Brinell (HB) max |
| 409 | 55 (380) | 25 (170) | 20 | 95 | 207 |
| 1.4512 | 380-560 | 210 | 25 |
Typical physical properties for annealed grade 409 stainless steels are given in table 3.
Table 3. Physical properties of 409 grade stainless steel in the annealed condition
| Grade | Density (kg/m³) | Elastic Modulus (GPa) | Mean Coefficient of Thermal Expansion (mm/m/°C) | Mean Coefficient of Thermal Expansion (mm/m/°C) | Mean Coefficient of Thermal Expansion (mm/m/°C) | Thermal Conductivity (W/m.K) | Thermal Conductivity (W/m.K) | Specific Heat 0-100°C (J/kg.K) | Electrical Resistivity (nW.m) |
| 0-100°C | 0-315°C | 0-538°C | at 100°C | at 500°C | |||||
| 409 | 7600 | 208 | 11.0 | 11.7 | 12.4 | 25.8 | 27.5 | 460 | 600 |
Grade Specification Comparison
Approximate grade comparisons for 409 stainless steel are given in table 4.
Table 4. Grade specifications for 409 grade stainless steel
| Grade | UNS | BS | BS | EN | EN | Swedish | Japanese |
| – | No. | EN | Name | SS | JIS | ||
| 409 | S40900 | 409S19 | – | 1.4512 | X6CrTi12 | – | SUH 409 |
These comparisons are approximate only. The list is intended as a comparison of functionally similar materials not as a schedule of contractual equivalents. If exact equivalents are needed original specifications must be consulted.
Possible Alternative Grades
Possible alternative grades to grade 409 stainless steel are given in table 5.
Table 5. Possible alternative grades to 409 grade stainless steel
| Grade | Why it might be chosen instead of 409 |
| 3CR12 | Similar corrosion resistance, easier welding and more readily available than 409, particularly in heavy sections. (409 may have better drawability than 3CR12.) |
| 304 | Better corrosion resistance and heat resistance but at higher cost. |
| 321 | Higher heat resistance than 409 or 304. |
| Aluminised steel | Lower resistance to exhaust gases, but at lower cost than stainless steel grade 409. |
Corrosion Resistance
Grade 409 resists atmospheric and exhaust gas corrosion. A light surface rust will form in most atmospheres; this rust retards further corrosion but makes the surface undesirable for decorative applications. The corrosion resistance is about the same as that of 3CR12 and the 12% chromium martensitic grades such as 410, and inferior to the 17% chromium grade 430.
Heat Resistance
Generally 409 is classified as resistant to scaling in intermittent service up to 850°C and up to 650°C in continuous service, but these temperatures are dependent upon the exact service environment.
Heat Treatment
Annealing – heat to 790-900°C and air cool. This grade cannot be hardened by thermal treatment.
Welding
Readily welded but a pre-heat of 150-260°C is recommended. Grade 409 or Grade 430 electrode or filler rods can be used, but AS 1554.6 pre-qualifies welding of 409 with Grade 309 rods or electrodes. These austenitic fillers result in a more ductile weld.
Post-weld annealing at 760-815°C improves weld ductility.
Post-weld annealing is not required when welding thin sections. Automotive exhaust tubing is typically welded without filler metal (autogenously).
All welding must be carried out with minimum heat input to reduce grain growth effects.
Applications
Typical applications include:
• Automotive exhaust systems
• Catalytic converters
• Mufflers
Related References:
1. Superferritic Stainless Steel
2. Ferritic Ferrite Stainless Steel
3. Ferritic Stainless Steel Grades Comparison Table
4. Compared with the ferritic stainless steel, duplex stainless steel vulnerable
5. 409L Heat Resistant Stainless Steel