Why is 316L stainless steel pipe magnetic?

Many customers ask why is 316L stainless steel pipe magnetic? They think they bought a low-quality pipe. In fact, there are many types of stainless steel pipes, which are mainly divided into austenitic, martensitic, and ferritic types according to their organizational structure. The austenitic type shows no or weak magnetic properties, while the ferritic and martensitic types are magnetic. Today, I will explain how the magnetic properties in 316L stainless steel pipes are generated.

The reasons why 316L stainless steel pipe magnetic:

First of all, stainless steel 316L tube belongs to austenitic structure, which is non-magnetic or weakly magnetic. However, thermal processing can cause changes in chemical composition, as when we perform thermal processing, the composition of the tissue can be segregated or the heat treatment method is inappropriate, which can easily lead to the formation of a small amount of martensite or ferrite. In this way, there will be a weak magnetic property in 316L stainless steel plate.

In addition, after cold processing, the arrangement structure of 316L stainless steel pipe will also transform into martensite. The greater the degree of cold deformation, the more martensitic transformation, and the greater the magnetic properties of the stainless steel pipe. For example, a batch of steel strips that are originally non-magnetic will increase in deformation after being made into round pipes; after being extruded into square pipes or shaped pipes from round pipes, the degree of deformation will increase a little more; and after pressing the square pipes into bent pipes, the degree of deformation will continue to increase.

After cold drawing, the stainless steel pipe 316L transforms its microstructure into martensite, which produces magnetic properties. The greater the deformation of the steel pipe, the more obvious the magnetic properties. The deformation of rectangular pipes is greater than that of round pipes, especially in the corner area, where severe deformation can produce magnetic properties. The magnetic properties of bent pipes are stronger than those of straight pipes.

When some industries use stainless steel as spare parts, they need to use 316L, a material with high corrosion resistance. However, in order to prevent the accessories from adsorbing iron filings and prevent the instrument from being affected by magnetic interference, do we need to abandon this material? No, 316 stainless steel pipes can be demagnetized. In order to eliminate the generation of magnetism caused by these factors, the magnetism can be eliminated by restoring and stabilizing the austenite structure through solid solution treatment.

Why is 316L stainless steel pipe magnetic? The material structure has its own weak magnetism. After being made into a stainless steel pipe, it needs to be heat treated, or the pipe wall generates heat during polishing, which will form a small amount of martensite or ferrite structure, and the material will increase the magnetism. If it is made into square or rectangular tubes, special-shaped tubes, or bent tubes, the deformation intensity of the material will increase, which will also increase the magnetism of the structure.

Therefore, when customers purchase 316L stainless steel pipes without specifying demagnetization with the merchant, the pipes they buy may have weak magnetic properties, which is normal and does not involve any actions such as inferior quality or counterfeiting.

Conclusion

Thank you for reading our article and we hope it can help you to have a better understanding of why is 316L stainless steel pipe magnetic. If you want to find more information about 316L stainless steel, we would advise you to visit Sino Stainless Steel.

As one the top suppliers of stainless steel products from China, Sino Stainless Steel offers customers high-quality stainless steel pipes, stainless steel strips, stainless steel coils, stainless steel plates, stainless steel sheets, stainless steel bars, and stainless steel tubes at an extremely competitive price.