409 SS Tubing

Sep 19

When it comes to stainless steel tubing, many options are available. From 304 to 316, each variant has its unique properties and applications. However, one type that often gets overlooked is 409 SS tubing. This type of tubing is specifically designed for automotive and exhaust applications. It is a ferritic stainless steel with good corrosion, thermal conductivity, and oxidation resistance. This blog post will delve deeper into the properties, uses, and composition of 409 SS tubing.

What is 409 SS Tubing?

409 SS Tubing is a heat-resistant stainless steel alloy commonly used in exhaust systems due to its strength and corrosion resistance. It contains 11% chromium, making it highly resistant to oxidation at high temperatures. Its excellent formability makes it suitable for welding and bending into tubing of various shapes and sizes, ideal for applications such as automotive exhausts.          

Composition of 409 SS Tubing

Also known as UNS S40900, 409 SS tubing contains approximately 10.5% to 11.75% chromium. However, it has a lower nickel content than other stainless steel grades, such as 304 and 316. The lower nickel content makes 409 SS tubing less expensive than other stainless steel types and less corrosion-resistant in certain environments. Moreover, carbon, silicon, and manganese are the other elements in 409 SS tubing. Combining these elements makes it ideal for high-temperature applications such as automobile exhaust systems.

Properties of 409 SS Tubing

409 SS tubing is a ferritic steel grade, which means it has a body-centered cubic crystalline structure. It has a density of approximately 7.7 g/cm³. Below are some of the key properties of 409 SS tubing:

Tensile strength: 380 Mpa

Yield strength: 207 Mpa

Elongation: 20%

Hardness: Rockwell B84

Uses of 409 SS Tubing

As mentioned earlier, Stainless Steel tubing is mostly used in automotive and exhaust applications. It is also used in applications requiring high heat and corrosion resistance. Here are some of the key uses of 409 SS tubing:

Automotive exhaust systems – 409 SS tubing’s high-temperature resistance makes it ideal for use in exhaust systems.

Industrial boilers – 409 SS tubing can handle high temperatures without corroding, making it an ideal material to be used inside industrial boilers.

Catalytic converters – 409 SS tubing’s high-temperature resistance makes it ideal for catalytic converters.

Fuel Lines – 409 SS tubing is used in fuel lines, where it is required to handle oil and gasoline.

Weldability of 409 SS Tubing

409 SS tubing is easy to weld, making it a popular choice in automotive and exhaust applications. It can be welded using all standard welding methods, such as gas tungsten arc welding (GTAW), gas metal arc welding (GMAW), and manual metal arc welding (MMAW). However, it is best to avoid using it in corrosive environments, as it may react with certain chemicals present in some industrial applications.


In summary, 409 SS tubing is an excellent choice for automotive and exhaust applications. It has good resistance to high temperatures, is easy to weld and is relatively inexpensive compared to other stainless steels. Moreover, its properties make it ideal for industrial boilers, catalytic converters, and fuel lines. However, 409 SS tubing has a low nickel content, reducing its corrosion resistance. Therefore, avoiding using it in corrosive environments or where high corrosion resistance is required is best.