Why does 316L stainless steel water pipe have magnetism

Many customers ask why the 316L stainless steel water pipes have magnetism? They think they have bought inferior pipes. In fact, there are many types of stainless steel pipes. According to their structure, they are mainly divided into austenitic type, martensitic type, and ferritic type. Generally, stainless steel pipes have some degree of pipe magnetism. The austenitic stainless steel mentioned earlier has no magnetism or weak magnetism, while ferritic and martensitic stainless steel have pipes with magnetic properties. Today, I will explain how the magnetism in the 316L stainless steel water pipes is generated. 

316L stainless steel water pipe 

Firstly, the stainless steel 316L pipe belongs to an austenitic structure and may be non-magnetic or weakly magnetic. However, thermal processing can alter the chemical composition. When we perform thermal processing, the microstructure components may segregate or the heat treatment method may be improper, which can easily result in the formation of a few martensite or ferrite structures. As a result, the 316L stainless steel water pipe will exhibit its own slight magnetic property. 

Furthermore, the arrangement structure of the 316L stainless steel pipes will also transform into martensite after cold processing. The greater the degree of cold processing deformation, the more martensite phase transformation occurs, and the greater the magnetic property of the stainless steel pipe becomes. For example, a batch of steel strips originally had no magnetic property, but after being made into round pipes, the deformation degree will increase; when the round pipes are extruded into square pipes or special-shaped pipes, the deformation degree slightly increases; then the square pipes are pressed into curved pipes, and the deformation degree continues to increase. 

In addition, the 316L stainless steel pipes undergo cold stretching processing, and their microstructure will transform into martensite, resulting in magnetism. The greater the cold stretching and bending deformation of the steel pipes, the more obvious the magnetism will be. The deformation of square and rectangular tubes is greater than that of circular tubes, especially the severe deformation at the corners will generate magnetism, and bent pipes are more magnetic than straight pipes. 

Some industries use stainless steel as components and require the use of 316L high corrosion-resistant material. However, in order to prevent the parts from adsorbing iron filings and to avoid magnetic interference with the instruments, should we abandon this material? No, 316 stainless steel tubes can be demagnetized. To eliminate the generation of magnetism caused by these factors, it is necessary to undergo solution treatment to restore and stabilize the austenitic structure, thereby eliminating the magnetism. 

Why is 316L stainless steel pipe magnetic? The material structure has weak magnetism. When stainless steel pipes undergo heat treatment or the surface is polished and heated, a small amount of martensite or ferrite structure will form, and the material will increase its magnetism. When making square, rectangular, special-shaped, or bent pipes, the deformation of the material leads to an increasing strength, which also enables the stainless steel structure to increase its magnetism. 

316L stainless steel water pipe 

Therefore, when customers purchase 316L stainless steel pipes, there is no need to cancel the demagnetization process with the merchant. The purchased pipes may have a slight magnetic property, which is normal. There are no issues of inferior quality or counterfeiting. So we have always emphasized to you that during the purchasing process, provide as much information as possible to the manufacturer, including performance requirements, application industries, etc. We will do this before demagnetization and shipment. 

It is particularly important to note that the magnetism of 316L stainless steel water pipes caused by these factors is completely different from that of other types of stainless steel pipes. That is to say, 316L stainless steel pipes always exhibit weak magnetism. Therefore, when purchasing 316L stainless steel water pipes, do not be tempted by low prices. Try to choose high-quality stainless steel pipes from well-known brands for purchase. After all, getting something for too little money usually leads to big losses.