A magnet sticking to a stainless steel basket does not automatically mean the wrong material was used. Find out how drawing and bending affect 304 stainless steel wire, what the magnet test can reveal and which checks belong in your specification.
Yes, 304 stainless steel can be magnetic after cold working. In its solution-annealed condition, it normally shows very little attraction to a handheld magnet. Drawing wire or bending it into a component can change that response. A magnet sticking to a finished basket is therefore not enough to prove that the material is incorrect.
For buyers and engineers ordering wire shelves, baskets or dividers, the useful question is what the observation means for the finished part. Material identification, corrosion resistance and magnetic performance require different checks.
Why is 304 stainless steel usually described as non-magnetic?
304 belongs to the austenitic family of stainless steels. Its structure in the solution-annealed condition produces a very weak magnetic response, which is why it is commonly described as non-magnetic.
The designation AISI 304 is commonly associated with European grade 1.4301, also known as X5CrNi18-10. When ordering, specify the applicable grade and product standard rather than relying on a general description such as “stainless wire”.
Stainless steel is a family of materials, not a single alloy. Ferritic, martensitic and duplex stainless steels can show a clear attraction to a magnet. Magnetic behaviour alone does not establish whether a material is stainless.
Why can a magnet stick to a 304 stainless steel wire basket?
Cold deformation can transform part of the austenitic structure into magnetic martensite. The extent of this change depends on the material composition and processing conditions.
For wire components, two manufacturing stages are particularly relevant:
- Wire drawing: reducing the wire diameter through drawing introduces cold work before the basket or shelf is formed.
- Bending and forming: shaping the wire introduces further deformation, which can increase the magnetic response locally.
This means that a straight section of drawn wire can already react to a magnet. A bend may show a different response, but there is no universal rule that every corner must be more magnetic than every straight section.
Comparing a finished wire basket with an annealed sheet sample is therefore not a reliable acceptance test. The two products may have different processing histories even when their nominal material grade is the same.
What does the stainless steel magnet test actually tell you?
A handheld magnet provides an observation of attraction under the conditions of that check. It does not provide a chemical analysis or a complete assessment of the component.
| Observation | Possible explanation | Useful next step |
|---|---|---|
| Little or no noticeable attraction | Consistent with an austenitic material with a low magnetic response | Check material documentation if the grade must be confirmed |
| Attraction along a wire section | Cold work introduced during wire processing may contribute | Review the supplied wire grade and condition |
| Different attraction around a bend | Local deformation and the test arrangement may affect the observation | Record the location and compare using a consistent method |
| A clear difference between delivered parts | The handheld test alone cannot establish the cause | Check traceability and investigate the relevant batches |
| Attraction where the specification requires low magnetic response | The part needs assessment against the agreed requirement | Use the specified measurement method and acceptance limit |
Does magnetic attraction mean the basket will rust?
A magnet test does not measure corrosion resistance. Attraction after cold working does not, by itself, show that 304 has lost its suitability for the application.
Corrosion performance must be assessed against the environment and surface condition. Chlorides, cleaning chemicals, temperature and retained deposits can all matter. The material and finishing requirements should reflect the actual operating conditions.
For a refrigeration basket, describe whether it holds packaged products, encounters spills or undergoes regular washing. Include the cleaning products and procedure in the brief. These details help establish requirements that cannot be checked with a magnet.
How should you check the material when receiving wire components?
Start with the purchase specification. Confirm what grade was ordered, which drawing revision applies and what documentation was agreed. A general catalogue description is not a substitute for the requirements attached to the order.
A practical receiving check can follow this sequence:
- Match the delivery to the order: verify the part number, quantity and drawing revision.
- Review the agreed material records: confirm that the documentation can be linked to the relevant supply.
- Inspect the component: check dimensions, mounting points, finish and other defined acceptance criteria.
- Record unexpected observations: identify the affected parts and the exact locations involved.
- Agree further verification if needed: use a suitable material identification or magnetic measurement method for the question being investigated.
For custom wire baskets, separate material verification from functional checks. A correct alloy does not confirm that the basket fits its runners, and a successful fit check does not confirm the alloy.
What if the component must have a very low magnetic response?
State that requirement before quotation and sampling. Specifying “304 stainless steel” alone does not define a maximum magnetic response after manufacture.
A measurable requirement may use relative magnetic permeability. The acceptance limit, measurement conditions and locations should be agreed for the finished component. This gives the manufacturer a requirement to assess before the production route is confirmed.
Include the relevant check in the sample and approval process. Keep the approved drawing and inspection requirements together so that repeat orders use the same criteria.
What should you include in a request for quotation?
For wire components in refrigeration and retail, provide:
- A drawing or reference sample with the main dimensions.
- The required material grade and any documentation requirements.
- The operating environment and cleaning procedure.
- The expected loads and mounting arrangement.
- The required finish and appearance criteria.
- Any magnetic performance requirement, including how it will be checked.
- Sample quantities, production quantities and delivery dates.
SHELMO manufactures wire baskets, shelves, dividers and other components to customer requirements, including parts in AISI 304 / 1.4301 stainless steel. Technical review and sampling help clarify the specification before series production.
Planning a stainless steel wire component? Send your drawing or sample details for a quotation, including any material or magnetic requirements that affect acceptance.
FAQ: 304 stainless steel and magnet testing
Is 304 stainless steel magnetic?
In the solution-annealed condition, 304 normally has a very weak magnetic response. Cold working can increase that response, so finished wire components may attract a magnet.
Why does a magnet stick to a stainless steel wire basket?
Drawing and bending can change the structure of 304 stainless steel and increase its magnetic response. Attraction alone does not prove that the wrong material was used.
Can a magnet confirm that a component is made from 304?
No. A handheld magnet cannot identify the chemical composition or confirm a specific grade. Use material traceability and, where necessary, an appropriate identification method.
Does magnetic attraction mean stainless steel will rust?
No. Magnetic attraction alone does not predict corrosion performance. The material, surface condition, operating environment and cleaning procedure must be assessed separately.
What should I specify if low magnetic response is essential?
Define a measurable requirement for the finished component, including the acceptance limit, test method and measurement locations. Agree these details before sampling and production.
