Aluminized Steel vs. 409 Stainless Steel
Both aluminized steel and 409 stainless steel are excellent products for automotive exhaust applications. Both offer excellent heat and corrosion resistance and both can be easily welded.
Aluminized steel is steel that has been hot-dip coated with an aluminum-silicon alloy containing between 5 and 11% silicon to promote better adherence. It offers more corrosion resistance than galvanized steel and is 20 times more heat resistant than cold-rolled steel and 5 times more heat resistant than galvanized steel.
Used widely in original equipment and aftermarket exhaust systems, aluminized steel is used by most muffler shops. It is a very long-life product and will generally outlast mufflers by years. It is very workable and accepts bends without stressing. The principal advantage of aluminized steel is its lower cost.
409 is a titanium stabilized ferritic stainless steel which means that it is a steel alloy containing chromium. It contains less nickel and more carbon than 304 stainless steel. Ferritics are best suited for high temperature applications that require corrosion resistance and high strength. The principal use of 409 stainless steel is automotive exhaust systems and most catalytic converter shells are made of 409.
More workable and stable than 304, 409 will accept bending and heat cycling better than 304. It resists both atmospheric and exhaust gas corrosion. It is magnetic due to its higher carbon content. Through chemical reaction, it oxidizes to a slight brownish hue which aids in corrosion resistance. While it does not polish well, it offers the advantages of higher strength, lower cost and longer life due to its heat handling qualities.
A Word About Tube and Pipe
Exhaust "Pipes" are actually made from tubing. Tubing is measured from the outside. So, our 3inch bends and "pipes" actually measure 3 inches outside diameter. Pipe - that used for plumbing - is measured by inside diameter.
Welding Aluminized and Stainless Steel
Both Aluminized Steel and our 409 Stainless Steel can be easily welded. The correct rod or wire should be used.