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Technical resource / P1478

Stainless Steel Magnetic Properties

Stainless steel is not simply magnetic or non-magnetic. Magnetic response depends on the alloy family, delivered condition, cold work, welding and the test method. Use this guide to screen grades, then define an acceptance requirement in the RFQ.

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Quick answer

Magnetic behavior follows the material structure

These are screening descriptions. A handheld magnet does not identify a grade or prove compliance with a low-permeability requirement.

Austenitic

Usually low response

Stable annealed austenitic grades are normally chosen where low permeability is needed. Cold forming can introduce a measurable response.

Ferritic

Magnetic

Ferritic grades such as 430 have a ferritic structure and are attracted by a magnet.

Martensitic

Magnetic

Martensitic grades are magnetic. Their final response also depends on heat treatment and product form.

Duplex

Magnetic

Duplex grades combine ferrite and austenite. Their ferrite phase produces magnetic behavior.

Procurement method

Specify the magnetic performance, not only the grade name

Low magnetic permeability needs a measurable limit and a stated test basis.

01 / DEFINE THE SCOPE

Name the material condition

State grade, product form, thickness, delivery condition, forming history and whether welded areas are included.

02 / SET THE TEST BASIS

Make acceptance auditable

Specify the maximum permeability or response, measurement method, field strength, test location and sampling basis.

03 / REQUEST EVIDENCE

Connect it to the supplied lot

Ask for the product standard, test record and material certificate tied to the heat or lot where required.

Grade paths

Compare the material families before selecting a form

Open the grade hubs for chemistry, product forms and procurement context. Final selection must reflect the actual service environment.

304 stainless steel Explore316 stainless steel Explore430 stainless steel Explore2205 duplex stainless steel ExploreStainless steel product hub ExploreTechnical resources hub Explore

Magnetic performance context

Define the material condition and the test basis together.

Magnetic response depends on alloy family and can also change with cold work, welding, forming and heat treatment. Make the material condition and verification route visible early.

  • Material condition
  • Test method
  • Acceptance limit

Evidence and limits

Use the governing specification for final acceptance

Magnetic response can change with processing. This guide does not replace a project specification, test procedure or supplier documentation.

Technical review

Stainless Steel Market technical team
Last reviewed: 2026-09-22

  • British Stainless Steel Association: magnetic response of stainless steel.
  • British Stainless Steel Association: cold work and magnetic permeability.
  • Outokumpu: stainless steel material families.