Will a magnet stick to stainless steel exhaust

Stainless steel exhaust systems can be made from different grades of stainless steel, and whether a magnet will stick depends on the specific grade used. Here's a clear breakdown based on material science and common practices in exhaust manufacturing.

Why Magnets Stick (or Don't) to Stainless Steel

Stainless steel is categorized into families based on its microstructure:

• Austenitic stainless steel(e.g., 304 or 316): These are non-magnetic in their standard annealed state due to their face-centered cubic crystal structure. Magnets won't stick or will only weakly attract if the material has been work-hardened (e.g., during bending or forming, which can induce some magnetism).
• Ferritic stainless steel(e.g., 409 or 430): These have a body-centered cubic structure, making them magnetic. Magnets will stick firmly.
• Martensitic stainless steel(e.g., 410): Also magnetic, but less common in exhausts.

The test is not always reliable, as cold-working or heat from welding can make austenitic steels slightly magnetic.

Do Magnets Stick to Stainless Steel Exhausts?

• Yes, for most standard exhausts: Many automotive stainless steel exhausts use ferritic grades like 409, which are magnetic and cost-effective with good heat resistance. A magnet will stick to these. This is common in cars, trucks, and motorcycles for affordability and performance in high-temperature, mildly corrosive conditions.
• No, for high-end or premium exhausts: If the exhaust is made from austenitic grades like 304 or 316 (often in aftermarket or performance systems), a magnet won't stick, or only weakly if work-hardened. These are "high-grade" stainless and non-magnetic.

To check your exhaust: Clean the surface and test with a strong magnet. If it sticks firmly, it's likely ferritic (low-grade stainless like 409). If not, it's austenitic (high-grade like 304).

Why Manufacturers Choose Different Grades for Exhausts

• Ferritic (magnetic, e.g., 409): Cheaper, good for heat and exhaust gases, but less corrosion-resistant in salty roads. Used in OEM exhausts.
• Austenitic (non-magnetic, e.g., 304): Better corrosion resistance, more expensive, used in premium or marine exhausts.

Gangsteel recommends non-magnetic 304 for custom exhausts in corrosive areas. For quotes on SA240 Gr 304, contact us—we specialize in ASME SA240 stainless steel plates for fabrication.