Products Description
Product Specifications
| Standards | ASTM A268/A268M |
| Steel Grades | TP405 TP410 TP430 TP443 TP446-1 TP446-2 TP409 TP439 TP430Ti TPXM-27 TPXM-33 18Cr-2Mo 29-4 29-4-2 26-3-3 25-4-4 TP468 |
| Equivalent Standards | EN 10088-2 / JIS G4305 |
| Outer Diameter (OD) | 6.00 mm – 114.3 mm |
| Wall Thickness (WT) | 0.50 mm – 4.00 mm |
| Length | 3/6/12m, customized |
| Surface Treatment | BA, 2B, Pickled, Polished |
| Production Process | TIG Welded / Cold Drawn |
| Condition | Bright Annealed |
Automotive exhaust systems are continuously exposed to high-temperature exhaust gases. Welded and drawn stainless steel tubing made from ferritic grades such as 409 and 439 offers excellent high-temperature oxidation resistance; notably, TP409 maintains stable performance at continuous operating temperatures up to 675°C.
During the manufacturing of cold-drawn welded tubing, the material undergoes cold drawing and a subsequent annealing process after welding. This eliminates the as-welded cast microstructure, producing fine, uniform equiaxed ferritic grains and ensuring a high degree of strength uniformity between the tube matrix and the weld seam. Furthermore, compared to commonly used heat-resistant austenitic grades like TP304/304L, materials such as 409, 439, and 441 offer lower material costs, a lower work-hardening rate during cold drawing, and a simpler annealing process.
Customized Services
- TORICH offers customization for non-standard dimensions, supporting outside diameters of 6.00 mm–114.3 mm and wall thicknesses of 0.50 mm–4.00 mm, as well as designs featuring variable wall thicknesses and special cross-sections.
- We provide end-forming services, including V-band clamp ends, ball-and-socket flared ends, swaged/reduced ends, expanded ends, and welding for angular, oval, and rectangular exhaust flanges.
- We offer bending services with a minimum bend radius of 1.0D, supporting custom non-integer radii and the forming of complex exhaust manifold geometries.
Chemical Composition
| Element | C | Mn | P | S | Si | Cr | Ni | Ti | Nb | Al | N |
|---|---|---|---|---|---|---|---|---|---|---|---|
| TP409 | ≤0.08 | ≤1.00 | ≤0.045 | ≤0.030 | ≤1.00 | 10.50–11.75 | ≤0.50 | 6×(C+N) ≤0.75 | - | - | - |
| TP439 | ≤0.07 | ≤1.00 | ≤0.040 | ≤0.030 | ≤1.00 | 17.00–19.00 | ≤0.50 | 0.20+4(C+N) ≤1.10 | - | ≤0.15 | ≤0.04 |
| TP441 | ≤0.03 | ≤1.00 | ≤0.040 | ≤0.015 | ≤1.00 | 17.50–19.50 | ≤1.00 | 0.10–0.60 | 9×C+0.30 ≤1.00 | - | ≤0.03 |
Mechanical Properties
| Property | Tensile Strength Rm | Yield Strength Rp0.2 | Elongation (50 mm gauge) | Hardness (HRB) |
|---|---|---|---|---|
| TP409 | ≥380 MPa (55 ksi) | ≥170 MPa (25 ksi) | ≥20% | ≤90 |
| TP439 | ≥415 MPa (60 ksi) | ≥205 MPa (30 ksi) | ≥20% | ≤90 |
| TP441 | ≥415 MPa (60 ksi) | ≥205 MPa (30 ksi) | ≥20% | ≤90 |
Possible Alternative Grades
- 304/304L stainless steel is a commonly used alternative material; compared to ferritic grades such as TP409 and TP439, 304L offers superior corrosion resistance, making it suitable for exhaust components exposed to humid environments and road salts.
- 309S stainless steel is a high-chromium-nickel alloy; compared to TP441, it is suitable for exhaust components operating in extremely high-temperature environments of approximately 1000°C.
- 18CrNb stainless steel is a ferritic stainless steel developed specifically for automotive exhaust systems, with a temperature resistance of approximately 850–900°C.
application areas
ASTM A268 welded and drawn stainless steel tubing is widely used throughout automotive exhaust systems, specifically in applications such as:
exhaust manifolds for automobiles and motorcycles; turbocharger inlet and oil return pipes; catalytic converter housings and substrate sleeves; front and rear muffler internals and resonator pipes; intermediate exhaust pipes and tailpipes; and Exhaust Gas Recirculation (EGR) cooler piping.
Products Show
Testing Equipment
Factory Equipment
Pickling equipment
Polishing equipment
Cold drawing equipment
Products Package
FAQ
Q: What are the maximum temperature ratings for TP409, TP439, and TP441?
A: Under continuous oxidation conditions, TP409 is approximately 675°C, TP439 is approximately 815°C, and TP441 is approximately 850°C. Peak temperatures for intermittent (cyclic) service can be about 50–100°C higher. Actual limits depend on the specific atmosphere, the presence of corrosive condensate, and mechanical loads.
Q: What are the bending characteristics of cold-drawn tubes?
A: In the annealed state, cold-drawn ferritic tubes exhibit an elongation of over 25% and possess good bending properties. We can supply finished bent tubes with bending radii ranging from 1.5D to 3D based on drawings, ensuring that ovality and wall thinning rates meet OE standards.
Q: Can you customize tubes with varying diameters or non-circular cross-sections?
A: Yes. Using processes such as cold-drawn tube-end forming (flaring, swaging, or upsetting), spinning, or hydroforming, we can deliver components featuring diameter transitions, ribs, or special cross-sections according to your drawings.
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