304 stainless steel will not be magnetic can not judge the merits and demerits of stainless steel

304 Stainless Steel will not be magnetic can not judge the merits and demerits of stainless steel
People often think that the magnet absorbs stainless steel, to verify its merits and falseness, does not absorb no magnetic, that is good, genuine; Suckers have magnetic, is considered to be fake fake. In fact, this is an extremely one-sided, impractical and wrong way of identifying.
There are many kinds of stainless steel, which can be divided into several categories according to the organizational structure at room temperature:
1, Austenitic body type: such as 304, 321, 316, 310, etc.
2, martensite or ferritin type: such as 430, 420, 410, etc.;
The austenitic body is non-magnetic or weakly magnetic, and the martensite or ferrite is magnetic.
Usually used as decorative tube plate stainless steel most is Austenitic type 304 material, generally speaking, no magnetic or weak magnetic, but because of smelting caused by chemical composition fluctuations or processing state may also appear magnetic, but this can not be considered counterfeit or unqualified, what is the reason?
As mentioned above, austenite is non-magnetic or weakly magnetic, while martensite or ferrite is magnetic. Due to improper segregation or heat treatment during smelting, a small amount of martensite or ferrite structure will be caused in austenitic 304 stainless steel. 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 martensitic, cold processing deformation, martensitic transformation, the greater the magnetic steel is. Like a batch of steel strip, the production of 76 pipe, no obvious magnetic sensation, production of 9.5 pipe. Because of the larger deformation of flapping bend, the magnetic sensation is more obvious. Because the deformation of the square Rectangular Tube is larger than that of the round tube, especially the corner part, the deformation is more intense and the magnetism is more obvious.
In order to completely eliminate the magnetic properties of 304 steel caused by the above reasons, the magnetic properties can be eliminated by high temperature solution treatment to restore the stable austenite structure.
In particular, because of the above reasons caused by the magnetic 304 stainless steel, and other materials of stainless steel, such as 430, carbon steel magnetic is not the same level, that is to say, the magnetic 304 steel always shows weak magnetism.
This tells us, if stainless steel with weak magnetism or no magnetism, should be identified as 304 or 316 material; If it is the same as the magnetism of carbon steel, it shows strong magnetism, because it is not 304 material.