People often think that magnet adsorption stainless steel, verify its advantages and disadvantages and authenticity, no magnetic absorption, that is good, genuine; Those who suck have magnetism, think it is fake fake. It is, in fact, a very partial and ineffectual way of identifying error.
There are many kinds of stainless steel, at room temperature according to the structure can be divided into several categories:
1. Austenitic body type: such as 304, 321, 316, 310, etc.
2. Martensite or ferritic shape: such as 430, 420, 410, etc.
Austenite is non-magnetic or weakly magnetic, martensite or ferrite is magnetic. Most of the stainless steel that uses as adornment tube plate is the 304 material that austenite body type pledges material, generally speaking be to do not have magnetism or weak magnetism, but because smelting causes chemical composition fluctuation or processing state to differ also may appear magnetism, but this cannot think is counterfeit or unqualified, what reason is this?
The above mentioned austenite is non-magnetic or weak magnetic, and martensite or ferrite is magnetic, due to composition segregation or improper heat treatment when smelting, will cause a small amount of martensite or ferrite structure in 304 stainless steel austenite. In this way, 304 stainless steel will have a weak magnetic.
In addition, 304 stainless steel after cold processing, the organizational structure will also martensite transformation, the greater the deformation of cold processing, the more martensite transformation, the greater the magnetic steel. As a batch of steel belt, production φ 76 tubes, no obvious magnetic induction, production φ 9.5 tubes. Because of the large deformation of the ling bend, the magnetic sensation is obvious. The production square rectangular tube is larger than the round tube because of the deformation, especially the corner part, the deformation is more intense and the magnetism is more obvious.
In order to completely eliminate the magnetism of 304 steel caused by the above reasons, the stable austenite structure can be restored by high temperature solution treatment, so as to eliminate the magnetism.
In particular, due to the above reasons caused by 304 stainless steel magnetic, and other materials of stainless steel, such as 430, carbon steel magnetic completely is not the same level, that is to say, 304 steel magnetic always show is weak magnetic.
This tells us that if the stainless steel with weak magnetic or no magnetic, should be identified as 304 or 316 material; If it is the same as the magnetic carbon steel, it shows strong magnetism, because it is not 304 material.