Stainless Steel is also with Magnetic: the difference between 304 and 201
There are various kinds of stainless steel. It can be divided into Austenitic stainless steel and Martensitic stainless steel or Ferritic stainless steel. Austenitic stainless steel is non-magnetic or feeble magnetic. While Martenistic or Ferritic is magnetic (but the magnetic is not as strong as Iron).
The stainless steel plate which is used for producing decorative tube is mostly Austenitic stainless steel grade 304 and 201. Generally speaking, those stainless steel is non-magnetic or feeble magnetic. However, it might be magnetic when its chemical composition is undulate during the process of smelt or for different process condition, that can’t be considered to be fake or unqualified. Why?
The mentioned Austenitic stainless steel is non-magnetic or weak magnetic, while Martenitic or Ferritic are magnetic. In the result of composition segregation or improper heat treatment is will causes Austenitic grade 304 and 201 stainless steel contains a little tissue of Martenitic or Ferritic. In this way, grade 304 and 201 might have weak magnetic.
In addition, the organization structure of grade 304 and 201 stainless steel may transform into Martenitic after cold treatment. The greater the degree of cold deformation, more Martensite transformation, the greater the magnetic properties of stainless steel. For instance, by using stainless steel strip of the same batch, there’s no obvious magnetic induction when producing round tubeΦ76. While there’s more magnetic induction when producing round tubeΦ9.5 because of cold bending deformation is greater. The deformation of producing rectangular tube is greater that producing round tube, especially the part of inflection angle. The more intense of deformation, the more obvious of magnetic.
In particular, the magnetic of stainless steel grade 304 and 201 cause by mentioned reasons is different from stainless steel of other grade, like grade430 and carbon steel which is completely not the same grade of steel. So to speak, the magnetic of stainless steel grade 304 and 201 are still showing the feeble magnetic.
What tells us is that we can distinguish the stainless steel grade might be Austenitic steel grade 304 and 201 if it shows the feeble magnetic or non-magnetic. While it might be other type of stainless steel, not Austenitic steel grade 304 and 201 if it shows magnetic which is as strong as iron.