Stainless steel balls are not a non-magnetic material! Stainless steel is divided into many types. It is usually believed that the magnet absorbs stainless steel to verify its quality and authenticity. If it does not absorb magnetism, it is considered to be good and genuine; if it absorbs magnetism, it is considered to be a fake. In fact, this is an extremely one-sided, impractical and wrong identification method.
Most of the stainless steel used for decorative tube sheets is austenitic 304 material, which is generally non-magnetic or weakly magnetic. However, magnetism may also occur due to chemical composition fluctuations or different processing conditions caused by smelting, but this cannot be considered as a fake or unqualified. What is the reason?
Ferrite is magnetic. Due to component segregation or improper 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 weak magnetism.
In addition, after cold working, the organizational structure of 304 stainless steel will also transform into martensite. The greater the cold working deformation, the more martensite transformation, and the greater the magnetism of the steel. For example, for a batch of steel strips, 76 tubes are in production, and there is no obvious magnetic induction, while 9.5 tubes are in production. The magnetic induction is more obvious due to the large cold bending deformation. The deformation of square and rectangular tubes is larger than that of round tubes, especially the corners, where 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 through high-temperature solid solution treatment to eliminate the magnetism. It should be pointed out in particular that the magnetism of 304 stainless steel caused by the above reasons is completely different from that of other stainless steels, such as 430 and carbon steel, that is, the magnetism of 304 steel always shows weak magnetism.
This tells us that if the stainless steel ball has weak magnetism or no magnetism at all, it should be judged as 304 or 316 material; if it shows strong magnetism like the magnetism of carbon steel ball, it should be judged as not 304 material.
