Is stainless steel magnetic?
As mentioned above, this is not an all-or-nothing answer. Some stainless steels are magnetic, while others are not. The decisive factor for magnetism is due to the microstructure of steel. Martensitic stainless steel (with a ferrite microstructure) is magnetic. Austenitic stainless steel contains nickel and is non-magnetic.
It is worth noting that the permeability of austenitic steel will change during processing. From the British Stainless Steel Association:
For example, cold work and welding tend to increase the content of martensite and ferrite in steel, respectively. A common example is in a stainless steel sink where the magnetic response of a flat drain pipe is small, while a pressed bowl has a high response due to the formation of martensite (especially at the corners).
In fact, austenitic stainless steels are used for "non-magnetic" applications, such as magnetic resonance imaging (MRI). In these cases, it is usually necessary to agree on the maximum permeability between the customer and the supplier. It can be as low as 1.44.
Meade Metal Stock Non-magnetic Stainless Steel
At Mead Metals, we have 300 series austenitic stainless steels in stock. Although 304 stainless steel is non-magnetic when it is first formed, it usually becomes magnetic after cold working. If the magnetic properties of the material are important for your next project, please contact one of our representatives and he will help you determine the best material for your application.
