It is often believed that using a magnet to test stainless steel is good. If the magnet does not attract or have magnetism, it is true; If it has magnetism, it's fake. In fact, this is an extremely one-sided and unrealistic method of misjudgment. So how to identify 304 stainless steel?

In general, stainless steel has both magnetic and non-magnetic properties. Austenite does not contain magnetism or weak magnetism, such as 201202304316, etc; Martensite or ferrite does not contain magnetism, such as 430, 420, 410, etc.

However, due to component segregation or improper heat treatment during the melting process, austenitic stainless steel contains a small amount of martensite or ferrite. In this way, 304 stainless steel will have weak magnetism.

In addition, during the cold working process, the microstructure of 304 stainless steel will change. The greater the cold working deformation, the greater the change in martensite, and the stronger the magnetic properties. Like a batch of numbered stainless steel wires, made into straight supports without obvious magnetic induction, but when bent into a long square or circular shape, due to the large cold bending deformation, some magnetism will be generated, especially in the bent part where the magnetism is more obvious.

In order to thoroughly remove the magnetization of the 304 stainless steel mentioned above, it is possible to repair the stable martensitic structure based on high-temperature solutions, and then remove the magnetization.