304 steel will also have magnetism and cannot judge the advantages and disadvantages of stainless steel

People often think that magnets adsorb stainless steel, verify its advantages and disadvantages and authenticity, do not absorb no magnetism, think that it is good, and the goods are genuine; If the smoker is magnetic, it is considered a counterfeit fake. In fact, this is an extremely one-sided and unrealistic wrong method of discernment.

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

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

2. Martensitic or ferritic type: such as 430, 420, 410, etc.; The austenitic type is non-magnetic or weakly magnetic, and martensitic or ferrite is magnetic.

Most of the stainless steel commonly used as decorative tube sheets is austenitic 304 material, generally speaking, it is non-magnetic or weakly magnetic, but due to smelting caused by chemical composition fluctuations or different processing states may also appear magnetic, but this can not be considered counterfeit or unqualified, what is the reason?

The austenite mentioned above is non-magnetic or weakly magnetic, while martensitic or ferrite is magnetic, due to improper component segregation or heat treatment during smelting, a small amount of martensitic or ferritic structure in austenitic 304 stainless steel will be caused. In this way, 304 stainless steel will have a weak magnetic color.

In addition, 304 stainless steel after cold working, the structure will also be converted to martensite, the greater the degree of deformation of cold working, the more martensitic conversion, the greater the magnetism of steel. Like a batch of steel strips, the production of Φ76 tubes, without obvious magnetic inductance, produces Φ9.5 tubes. Due to the large deformation of the bend, the magnetic induction is obvious, and the production of square rectangular tube is larger than the round tube due to the deformation, 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 stable austenite structure can be restored by high-temperature solution treatment, thereby eliminating magnetism.

In particular, the magnetism of 304 stainless steel caused by the above reasons is not at the same level as the magnetism of other stainless steels, such as 430 and carbon steel, that is to say, the magnetism of 304 steel always shows weak magnetism.

This tells us that if the stainless steel strip is weak magnetic or not magnetic at all, it should be judged as 304 or 316 material; If it shows strong magnetism like the magnetic properties of carbon steel, it is judged to be 304 material.