Why is stainless steel magnetic?
2022-07-19

People often think that magnet adsorption stainless steel, and verify its pros and cons, no magnetic suction, that is good, the real price;Suction magnetic, it is considered to be a fake.In fact, this is a very one-sided, not practical error of discrimination method.

There are many kinds of stainless steel, which can be divided into several types according to the structure at room temperature:

1.Austenitic body type: such as 304, 321, 316, 310, etc.

2.Martensite or ferrite body type: such as 430, 420, 410, etc.

Austenitic bodies are non - magnetic or weak magnetic, and martensite or ferrite is magnetic.

Usually used as decorative stainless steel tube plate is mostly austenitic 304 material, generally speaking is no magnetic or weak magnetic, but because of smelting caused by chemical composition fluctuations or different processing state may also appear magnetic, but this can not be considered fake or unqualified, what is the reason for it?

As mentioned above, austenite is non-magnetic or weak magnetic, while martensite or ferrite is magnetic. Due to improper composition segregation or heat treatment during smelting, a small amount of martensite or ferrite tissue in austenite 304 stainless steel will be caused.In this way, 304 stainless steel will have a weak magnetic.

In addition, 304 stainless steel after cold processing, the structure will also be transformed to martensite, the greater the cold processing deformation degree, the more martensite transformation, the greater the magnetic properties of steel.As a number of steel strip, the production of Φ 76 tube, no obvious magnetic induction, Φ 9.5 tube production.Due to the large deformation of the winding magnetic induction is obvious, the production of square rectangular tube due to the amount of deformation is larger than that of the round tube, especially the corner part, the deformation is more intense and the magnetic is more obvious.

In order to completely eliminate the magnetism of 304 steel caused by the above reasons, the stable austenite structure can be recovered by high temperature solid solution treatment, so as to eliminate the magnetism.

In particular, because of the above reasons caused by 304 stainless steel magnetic, and other materials of stainless steel, such as 430, carbon steel magnetic is not the same level, that is to say, 304 steel magnetic always show weak magnetic