What SS is not magnetic?

What Stainless Steel is Not Magnetic?

Stainless steel grades that are non-magnetic in their annealed (heat-treated) condition are primarily austenitic stainless steels, due to their face-centered cubic (FCC) crystal structure, which does not support magnetism. The most common non-magnetic stainless steel grades under ASME SA 240 include:

• SA 240 GR 304 (AISI 304, UNS S30400, 1.4301): Known for its SA 240 304 non magnetic properties, excellent corrosion resistance, and versatility in applications like plat stainless 304 and SA 240 GR 304 pipe.
• SA 240 GR 304L: Low-carbon variant of 304, also non-magnetic, with enhanced weldability.
• SA 240 GR 316 (AISI 316, UNS S31600, 1.4401): Molybdenum-enhanced for chloride resistance, non-magnetic in annealed state.
• SA 240 GR 316L: Low-carbon 316, non-magnetic, ideal for welded applications.
• SA 240 GR 321 (AISI 321, UNS S32100, 1.4541): Titanium-stabilized for high temperatures, non-magnetic in annealed condition.
• SA 240 GR 201 (AISI 201, UNS S20100, 1.4372): Low-nickel, high-manganese, non-magnetic austenitic grade, a cost-effective alternative to 304.

These grades are non-magnetic because their austenitic structure, stabilized by nickel, manganese, or nitrogen, does not support ferromagnetic properties. Gangsteel’s sa 240 gr 304 and sa 240 gr 304l plates are prime examples of non-magnetic stainless steels.

Why Some Stainless Steels Are Magnetic

Stainless steels with ferritic or martensitic microstructures are magnetic due to their body-centered cubic (BCC) or body-centered tetragonal (BCT) crystal structures. Common magnetic grades under SA 240 include:

• SA 240 GR 410 (UNS S41000): Martensitic, high strength, moderate corrosion resistance, used in cutlery.
• SA 240 GR 430 (UNS S43000): Ferritic, good corrosion resistance, used in automotive trim.
• SA 240 GR 409 (UNS S40900): Ferritic, cost-effective, used in exhaust systems.

Duplex stainless steels(e.g., SA 240 Type 2205, UNS S32205/S31803) are partially magnetic due to a mixed austenitic-ferritic structure. See sa 240 type 2205.

Even non-magnetic austenitic grades like SA 240 GR 304 can exhibit slight magnetism under certain conditions:

• Cold Working: Processes like rolling or bending (e.g., plat SS 304 3mm) can induce martensitic transformation, creating magnetic regions. Heavy cold work increases magnetism.
• Welding: Welded areas (e.g., SA 240 GR 304 pipe) may develop slight magnetism due to ferrite formation.
• Contamination: Iron particles from tools can cause apparent magnetism on surfaces.

Properties of SA 240 GR 304 (Representative Non-Magnetic Grade)

SA 240 GR 304 is a widely used non-magnetic stainless steel, ideal for applications requiring no magnetic interference.

Chemical Composition

• Nickel: Stabilizes the austenitic structure, ensuring SA 240 304 non magnetic properties.
• Chromium: Enhances corrosion resistance.

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

Mechanical Properties

Applications Leveraging Non-Magnetic Properties

Non-magnetic stainless steels like SA 240 GR 304, 304L, and 316L are ideal for:

• Food Processing: Tanks and plat stainless 304, ensuring hygiene and no magnetic interference.
• Medical Devices: MRI-compatible instruments leveraging SA 240 304 non magnetic properties.
• Electronics: Components requiring non-magnetic behavior to avoid interference.
• Chemical Industry: Vessels and SA 240 GR 304 pipe for mild corrosives.

For chloride-heavy environments, explore sa 240 gr 316l; for high temperatures, see sa 240 gr 321.

Pricing and Availability

As of October 14, 2025, 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.

Why Choose Gangsteel?

Gangsteel provides certified non-magnetic SA 240 GR 304 plates with competitive SS 304 plate price. For quotes or to learn what is SA 304, visit our astm a 240 stainless plate page or email admin@gangsteel.com.