Is stainless steel magnetic? Which grades are and which are not
Short answer: it depends on the grade. The most common stainless steels, 304 (A2) and 316 (A4), are austenitic and hardly or not magnetic. Ferritic stainless steel (for example 430) and martensitic stainless steel (410, 420, used in knives) are magnetic. Cold-worked parts of 304, such as edges, bends and wire, can become slightly magnetic. If you want to use a magnet on non-magnetic stainless steel, glue or screw on a steel plate.
Stainless steel grades and magnetism
| Grade | Type | Magnetic? | Where you find it |
|---|---|---|---|
| 304 / 1.4301 (A2) | austenitic | no (slightly after cold working) | worktops, sinks, pans, bolts |
| 316 / 1.4401 (A4) | austenitic | no | marine fittings, swimming pools, food industry |
| 430 / 1.4016 | ferritic | yes | fridge doors, dishwasher fronts, cooker hoods |
| 409 / 441 | ferritic | yes | exhausts |
| 410 / 420 | martensitic | yes | knives, scissors, tools |
| 2205 duplex | austenitic-ferritic | yes, partly | industry, offshore |
Why is one stainless steel magnetic and another not?
The difference lies in the crystal structure. Because of nickel, austenitic stainless steel (304, 316) has a structure in which the magnetic moments of the atoms do not align together. Ferritic and martensitic stainless steels contain little or no nickel and have a structure like ordinary steel: they are ferromagnetic. Bending or rolling can transform part of austenitic stainless steel into a magnetic structure, which is why a magnet sometimes sticks slightly to an edge or corner.
How do you test it?
- Hold a strong neodymium magnet, for example Ø10 x 5 mm, against the surface.
- It sticks firmly: ferritic or martensitic, fine for magnets.
- You feel a slight pull but it slides off: cold-worked 304; not suitable for hanging things.
- Nothing: 304/316; you need a steel counter plate.
Using a magnet on stainless steel anyway
- Glue a thin steel plate or strip behind or on the stainless steel (for example with two-component adhesive or double-sided tape).
- Use two magnets: one at the back, one at the front. Thin stainless steel lets the field through. See do magnets work through materials?
- Choose a self-adhesive magnet with a counter plate for light applications.
Frequently asked questions
Why doesn't a magnet stick to my stainless steel fridge?
Some fridges have a 304 stainless steel front or a stainless-look layer on aluminium. A magnet will not stick to it. Fridges with 430 stainless steel are magnetic.
Is stainless steel on a fishing magnet rope or bolt a problem?
No. Stainless steel bolts and eyes are used precisely because they do not rust. The magnet itself sits in a steel pot.
Can you use a magnet to tell real stainless steel from chrome-plated steel?
Partly: chrome-plated steel is always magnetic, 304/316 is not. But 430 stainless steel is also magnetic, so a magnet that sticks does not prove it is not stainless steel.
Read also
- How does a magnet work? Which materials are magnetic
- How is holding power determined?
- Which filter magnet should you choose? (magnets in a stainless steel housing)
Need help choosing? Use the Magnet Advisor or contact us.
