Stainless steel welded pipes are also widely used in production. Many people only know that stainless steel welded pipes have anti-oxidation and anti-corrosion properties, but few know that they are magnetic. Now let's talk about how to identify the magnetism of stainless steel welded pipes.
Austenite is non-magnetic or weakly magnetic, while martensite or ferrite is magnetic. Due to composition segregation during smelting or improper heat treatment, a small amount of martensite or ferrite structure may occur in austenitic stainless steel. In this way, stainless steel will have a faint magnetic property. In addition, after cold working, the microstructure of stainless steel will also transform into martensite. The greater the degree of deformation during cold working, the more martensite transformation occurs, and the greater the magnetic property of the steel.
Like a batch of steel strips, the production of Φ76 tubes, no obvious magnetic induction, the production of Φ9.5 tubes. Due to the large bending deformation, the magnetic induction is more obvious. For the production of square and rectangular tubes, the deformation is greater than that of round tubes, especially at the folded corners, where the deformation is more intense and the magnetic induction is more pronounced. To completely eliminate the magnetism of steel caused by the above reasons, high-temperature solution treatment can be carried out to restore the stable austenite structure, thereby eliminating the magnetism. To sum up, the magnetism of stainless steel welded pipes caused by the above reasons is not at the same level as that of other types of stainless steel, such as 430 and carbon steel. In other words, the magnetism of steel always shows weak magnetism.
This tells us that if the stainless steel strip is weakly magnetic or completely non-magnetic, it should be identified as or 316 material. If it shows strong magnetism like carbon steel, it should be identified as not being of the same material. The above points are the more common explanations of the magnetic properties of stainless steel welded pipes.
