How to distinguish whether the magnetic stainless steel

People often think that the magnet adsorbed stainless steel, to verify its advantages and disadvantages and authenticity, non-magnetic non-suction, that is good, genuine; sucked those who have magnetic, then that is counterfeit fakes. In fact, this is an extremely unilateral and imprecise method of identifying mistakes. A wide range of stainless steel, according to the structure at room temperature can be divided into several categories: 1. Austenitic: such as 304,321,316,310, etc .; 2. Martensite or ferrite type: such as 430,420,410, etc .; austenitic type is non-magnetic or weakly magnetic, martensite or ferrite is magnetic. Stainless steel, usually used for decorative tubesheet, is austenitic 304. Generally speaking, it is non-magnetic or weakly magnetic. However, it may also be magnetized due to chemical composition fluctuation or processing due to smelting, but this can not be considered as Counterfeit or unqualified, what is the reason? Mentioned above, austenite is non-magnetic or weakly magnetic, and martensite or ferrite is magnetic, due to smelting composition segregation or improper heat treatment, can cause austenitic stainless steel in a small amount of martensite or ferrite Body tissue. In this way, 304 stainless steel will have a weak magnetic. In addition, 304 stainless steel after cold work, the organizational structure will be transformed into martensite, cold deformation, the greater the martensitic transformation, the greater the magnetic steel. As a number of steel strip, production Φ76 tube, no significant magnetic induction, production Φ9.5 tube. Deformation due to a larger bending magnetic deformation was obvious, the production side of the rectangular tube deformation due to the large tube, especially the corner part of the deformation more intense magnetic more obvious. To completely eliminate the above reasons caused by the 304 steel magnetic, high temperature solution treatment can open recovery of stable austenite, thereby eliminating the magnetic. In particular, the magnetic properties of 304 stainless steel caused by the above reasons are totally different from the magnetic properties of other materials such as 430 and carbon steel. That is to say, the magnetic properties of 304 steel always show weak magnetic properties. This tells us that if the stainless steel with weak magnetic or non-magnetic, should be identified as 304 or 316 material; if the same with the magnetic carbon steel, showing ferromagnetism, because it is not identified as 304 material.