304 stainless steel has weak magnetism

Austenitic stainless steel is non-magnetic or weak magnetic, and austenitic ferritic duplex stainless steel is magnetic.

304 stainless steel is austenitic stainless steel, but why does it contain a small amount of martensite or ferrite?

During smelting or forging, component segregation or improper heat treatment will cause a small amount of martensite or ferrite in 304 stainless steel. In this way, 304 stainless steel will have weak magnetism.

In addition, after cold working, the structure of 304 stainless steel will also be transformed into martensitic stainless steel. The greater the deformation of cold working, the more martensitic transformation, and the greater the magnetism of 304 stainless steel.

For example, the originally nonmagnetic 304 stainless steel plate produced magnetism during the cold stretching process, that is, the part with the largest deformation has the largest magnetism.

In order to completely eliminate the magnetism of 304 stainless steel plate caused by the above reasons, the austenitic structure can be restored by high temperature solution treatment, that is, the martensite or ferrite can be transformed into austenite to eliminate the magnetism.

It is normal for 304 stainless steel to produce magnetism due to the above reasons.