How to identify 304 stainless steel through magnetism: there are still misunderstandings about 304 stainless steel in the stainless steel market. Some people think that stainless steel can be absorbed by magnets, stainless iron can be absorbed, stainless steel can not be absorbed, and good stainless steel is not magnetic. However, from this point of view, I will judge how to distinguish 304 stainless steel through this magnetic property.
Some people often think that the magnet is used to test the quality of stainless steel. The magnet is not attractive, non-magnetic and genuine; If it is magnetic, it is considered to be a fake. In fact, this is an extremely one-sided, impractical and wrong discrimination method.
Generally speaking, stainless steel has magnetic and non-magnetic. Austenite type is non-magnetic or weakly magnetic, such as 201, 202, 304, 316, etc; Martensite or ferrite is magnetic, such as 430, 420, 410, etc.
However, due to component segregation or improper heat treatment during smelting, there will be a small amount of martensite or ferrite in Austenitic 304 stainless steel. In this way, 304 stainless steel will have weak magnetism.
In addition, after cold working, the microstructure of 304 stainless steel will also be transformed into martensite. The greater the cold working deformation, the more martensite transformation, and the greater the magnetism. Like the stainless steel wire of the same batch number, it is made into a straight support without obvious magnetic induction, but when it is bent into a rectangle or circle, it will produce some magnetism due to large cold bending deformation, especially in the corner part.
In order to eliminate the magnetism of the above 304 stainless steel, the stable austenite structure can be restored by high temperature treatment, so as to eliminate the magnetism.
In particular, the magnetism of 304 stainless steel caused by the above reasons is not at the same level as that of other stainless steels, such as 430 and carbon steel, that is, the magnetism of 304 stainless steel is always weak.
