Home > Knowledge > Content
Why stainless steel also with magnetic?
Apr 06, 2017

Why 304 stainless steel also with magnetic?

As we all know use the way of using a magnet adsorption to check stainless steel material and verify its quality and authenticity, not without magnetic absorption, think is good and true;Magnetic suction, is believed to be fake fake.Actually, this is not real even wrong.

There are many types of stainless steel, room temperature according to the organizational structure can be divided into several categories:
1. The austenite size, such as 304, 321, 316, 310, etc;
2. Martensite or iron grain size: such as the 430, 420, 410, etc;
Austenite size is non-magnetic or weak magnetic, martensite and ferrite are magnetic.
304 stainless steel round pipe,304 stainless steel rectangular pipes often used as decorative tube,generally is non-magnetic or weak magnetic, but caused by smelting chemical composition may also appear different magnetic fluctuations or processing status, but it cannot be considered a counterfeit or substandard, what reason is this?

Mentioned above austenite is non-magnetic or weak magnetic, martensite and ferrite stainless steel is magnetic, due to improper smelting composition segregation or heat treatment, can cause a small amount of martensite in the austenitic stainless steel 304 or ferrite organization.In this way, will with weak magnetic 304 stainless steel.

In addition, 304 stainless steel after cold working, the organization structure will be to the martensitic transformation, the greater the degree of cold deformation, the greater martensitic transformation, the more become the magnetic steel.


As a number of steel strip, the production of Φ 76 tube, no obvious magnetic induction, Φ9.5 tube production.Because bending deformation is magnetically sensitive to some apparently, rectangular tube production due to the deformation is bigger than circular tube, especially the Angle, more intense magnetic more obvious deformation.

To eliminate the causes of 304 magnetic steel treated by high temperature solid solution stability returns austenitic organization, thus eliminating magnetism.

In particular, due to the above causes of 304 stainless steel magnetic, and other stainless steel materials, such as 430, carbon steel magnetic completely is not the same level, that is to say 304 magnetic always shows the weak magnetic steel.

This tells us, if stainless steel is weak magnetic or completely without magnetic, should distinguish material for 304 or 304;If the magnetic with carbon steel, show strong magnetic, we usually judge the material is not 304.

We suggest that when you purchase stainless steel products please choose the right supplier.Only we cooperate you know us clearly!

welcome to contact us by email:song@songalloy.com