We know that there are many types of stainless steel belts, the common ones are 201, 304, 430, 301, 316, etc. The properties of these different types of products are different, and problems may occur if they are confused. Therefore, how to distinguish the type of cold-rolled stainless steel strip has become an important issue.
First of all, it should be understood that stainless steel strips can be divided into austenitic and martensitic types according to their structure. Most of the stainless steel strips usually used for decorative tube sheets are austenitic 304 materials, which are generally non-magnetic or weakly magnetic, but may also appear magnetic due to fluctuations in chemical composition or different processing conditions caused by smelting, but this cannot be considered is counterfeit or substandard.
Secondly, austenite is non-magnetic or weakly magnetic, while martensite or ferrite is magnetic. Due to component segregation or improper heat treatment during smelting, a small amount of martensite or ferrite in austenitic 304 stainless steel will be caused. organize. In this way, 304 stainless steel will have weak magnetism.
In addition, after cold working of 304 stainless steel, the structure will also be transformed to martensite. The greater the cold working deformation, the more martensite transformation, and the greater the magnetic properties of the steel. Like a batch of steel strips, Φ76 tubes are produced without obvious magnetic induction, and Φ9.5 tubes are produced. The magnetic induction is more obvious due to the large deformation of the bending and bending. 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 magnetic force is more obvious.
If you want to completely eliminate the magnetic properties of 304 steel caused by the above reasons, you can restore the stable austenite structure through high-temperature solution treatment, thereby eliminating the magnetic properties.
In particular, the magnetic properties of 304 cold-rolled stainless steel strips caused by the above reasons are not at the same level as other stainless steel strips, such as 430 and carbon steel, that is to say, the magnetic properties of 304 steel always show Weak magnetic.