ASTM A268 TP409 Stainless Steel Seamless Tube

What Is ASTM A268 TP409

ASTM A268 TP409 is a titanium-stabilized ferritic stainless steel seamless tube designed for automotive exhaust systems and other high-temperature corrosion applications. The seamless structure ensures uniform wall thickness, freedom from weld seams, and enhanced pressure containment reliability for components operating under extreme thermal cycling.

Chemical Composition

Limits for TP409, UNS S40900, are carbon 0.08 percent maximum, silicon 1.00 percent maximum, manganese 1.00 percent maximum, phosphorus 0.045 percent maximum, sulfur 0.030 percent maximum, chromium 10.5 to 11.7 percent, nickel 0.5 percent maximum, and titanium 6 times the carbon content minimum up to 0.75 percent maximum. The titanium stabilization minimizes chromium carbide precipitation at high temperatures up to about 816 degrees C, maintaining corrosion resistance in exhaust service.

Mechanical Properties

TP409 tube has a minimum tensile strength of 380 MPa, a minimum yield strength of 170 MPa, and a minimum elongation of 20 percent in the annealed condition. The moderate strength and ferritic ductility support bending and forming into complex exhaust geometries.

Manufacturing and Quality

The tube is produced by precision seamless processes such as extrusion or piercing, followed by solution annealing or heat treatment. Quality control includes raw material PMI validation, in-process eddy current and ultrasonic non-destructive testing, and 100 percent dimensional inspection, with traceable inspection records for every batch.

Applications

TP409 tubes are used in automotive exhaust manifolds, catalytic converter casings, exhaust piping, and industrial exhaust systems where a balance of cost-effectiveness, corrosion resistance, and thermal durability is required. The grade resists exhaust gas oxidation and intergranular corrosion during thermal cycling.

Procurement Guidance

When ordering, specify the outside diameter, wall thickness, length, finish such as bright annealed or pickled and annealed, and certification requirements. Confirm the grade designation, TP409 or UNS S40900, against your specification, and request mill test certificates for traceability.

Frequently Asked Questions

Q: What is the chromium content of TP409?

A: 10.5 to 11.7 percent.

Q: Why is titanium added to TP409?

A: To prevent chromium carbide precipitation up to about 816 degrees C.

Q: What is the tensile strength of TP409?

A: 380 MPa minimum.

Q: What applications use TP409 tube?

A: Exhaust manifolds, catalytic converter casings, and industrial exhaust piping.

Q: Is TP409 suitable for marine service?

A: No, its low chromium and lack of molybdenum limit chloride resistance.

Q: What sizes are available?

A: Outer diameters up to 219.1 mm with walls up to 20 mm on request.

Contact us for ASTM A268 TP409 seamless tubes with certified material reports and automotive-grade quality control.