Is type 304 SS magnetic?

Is Type 304 Stainless Steel Magnetic?

Type 304 stainless steel is generally non-magneticin its annealed (heat-treated) condition, meaning it does not stick to magnets under normal circumstances. This is due to its austenitic microstructure, which is characteristic of 300-series stainless steels like Type 304 (SA 240 GR 304) and Type 316. The non-magnetic property, often referred to as SA 240 304 non magnetic, makes Type 304 ideal for applications requiring minimal magnetic interference, such as food processing equipment, medical devices, and electronics.

However, Type 304 can exhibit slight magnetism under specific conditions:

• Cold Working: Processes like rolling, bending, or forming (e.g., for plat SS 304 3mm or plate 2 mm SUS 304) can induce a partial transformation from austenite to martensite, a magnetic phase. The degree of magnetism depends on the extent of cold work—light deformation causes minimal magnetism, while heavy deformation (e.g., in drawn wire or thin sheets) increases it.
• Welding: Welded areas, such as in SA 240 GR 304 pipe, may develop slight magnetism due to microstructural changes or ferrite formation in the weld zone.
• Surface Contamination: Iron particles or carbon steel residue (e.g., from tools) on the surface can cause Type 304 to appear magnetic, though this is superficial and not a property of the material itself.

In practical terms, annealed Type 304 plates or sheets (e.g., plat stainless 304) will not stick to a magnet, but heavily cold-worked or welded Type 304 may show weak attraction. This distinguishes Type 304 from ferritic (e.g., SA 240 GR 430) or martensitic (e.g., SA 240 GR 410) stainless steels, which are inherently magnetic.

Why is Type 304 Stainless Steel Non-Magnetic?

The non-magnetic nature of Type 304 stainless steel is due to its austenitic crystal structure, stabilized by its chemical composition:

Chemical Composition

• Nickel (8-10.5%): Stabilizes the austenitic structure, ensuring SA 240 304 non magnetic properties.
• Chromium (18-20%): Enhances corrosion resistance without affecting magnetism.
• Low Carbon (≤0.08%): Maintains austenitic stability and weldability, though Type 304L (≤0.03%) is preferred for critical welds. See sa 240 gr 304l.

For detailed specifications, refer to our SS 304 data sheet.

Testing Type 304 for Magnetism

To confirm Type 304’s non-magnetic properties:

• Magnet Test: Place a magnet on an annealed Type 304 surface (e.g., plat stainless 304). No attraction confirms non-magnetic behavior. Weak attraction suggests cold-working or contamination.
• Chemical Analysis: Use a portable XRF analyzer to verify composition, distinguishing Type 304 from magnetic grades like SS 201 (lower nickel) or SA 240 GR 430 (ferritic).
• Supplier Certification: Check the mill test certificate (MTC) for SA 240 GR 304 to ensure annealed condition.

Comparison with Other Grades

• Type 304L: Also non-magnetic, with similar behavior but lower carbon for better weldability. See sa 240 gr 304l.
• Type 316/316L: Non-magnetic, with molybdenum for better chloride resistance. See sa 240 gr 316l.
• Type 201: Non-magnetic but less corrosion-resistant than Type 304 (SS204 vs SS 304 is a misnomer; SS 201 is correct). See sa 240 gr 201.
• Type 430/409: Ferritic, inherently magnetic, with lower corrosion resistance.

For high-temperature applications, explore sa 240 gr 304h or sa 240 gr 321.

Applications Leveraging Non-Magnetic Properties

Type 304’s non-magnetic properties are critical for:

• Food Processing: Tanks and equipment (e.g., plat stainless 304) requiring hygiene and no magnetic interference.
• Medical Devices: MRI-compatible instruments leveraging SA 240 304 non magnetic properties.
• Electronics: Non-magnetic components to avoid interference.
• Chemical Industry: Vessels and SA 240 GR 304 pipe for mild corrosives.

For chloride-heavy environments, consider sa 240 gr 317l.

Pricing and Availability

As of October 14, 2025, Type 304 (SA 240 GR 304) plate prices (2B finish, 3-6mm) range from $1.55-$3.50/kg globally. Gangsteel offers $1.60/kg FOB (MOQ 1 ton) for sa 240 gr 304 plates, including sizes like plate 2 mm SUS 304, with finishes like 2B, No.1, and polished. Our SS 304 plate price is 5-10% below market averages.

Why Choose Gangsteel?

Gangsteel provides certified Type 304 stainless steel plates with consistent SA 240 304 non magnetic properties and competitive SS 304 plate price. Our 600+ ton inventory supports global delivery for applications from plat stainless 304 to heavy plates. For quotes or to learn more about Type 304, visit our astm a 240 stainless plate page or email admin@gangsteel.com.