Why does stainless steel also have magnetism?
People often think that magnets adsorb stainless steel materials to verify their quality and authenticity, and that they are good and genuine without magnetism; If the inhaler has magnetism, it is considered a counterfeit. In fact, this is an extremely one-sided and unrealistic method of identifying errors.
There are various types of stainless steel, which can be divided into several categories according to their organizational structure at room temperature:
1. Austenitic body type: such as 304, 321, 316, 310, etc;
2. Martensite or ferrite type: such as 430, 420, 410, etc;
Austenitic type is non magnetic or weakly magnetic, while martensite or ferrite is magnetic.
The stainless steel commonly used for decorative tube sheets is mostly austenitic 304 material, which is generally non magnetic or weakly magnetic. However, magnetism may also occur due to fluctuations in chemical composition or different processing conditions caused by smelting. However, this cannot be considered as counterfeit or unqualified. What is the reason for this?
As mentioned above, 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 structure can be formed in austenitic 304 stainless steel. In this way, 304 stainless steel will have weak magnetism.
In addition, after cold working, the microstructure of 304 stainless steel will also transform into 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, production Φ 76 tubes, no obvious magnetic induction, production Φ 9.5 Tube. Due to the large deformation caused by cold bending, the magnetic induction is more pronounced. The production of square rectangular tubes has a greater deformation than circular tubes, especially in the angled part, which causes more intense deformation and more pronounced magnetic induction.
To completely eliminate the magnetism of 304 steel caused by the above reasons, stable austenite structure can be restored through high-temperature solid solution treatment, thereby eliminating magnetism.
It should be pointed out that the magnetism of 304 stainless steel caused by the above reasons is completely different from that of other materials such as 430 and carbon steel, which means that the magnetism of 304 steel always shows weak magnetism.
This tells us that if stainless steel has weak magnetism or no magnetism at all, it should be classified as 304 or 316 material; If it exhibits strong magnetism similar to carbon steel, it should be distinguished as not being made of 304 material.
There are various types of stainless steel, which can be divided into several categories according to their organizational structure at room temperature:
1. Austenitic body type: such as 304, 321, 316, 310, etc;
2. Martensite or ferrite type: such as 430, 420, 410, etc;
Austenitic type is non magnetic or weakly magnetic, while martensite or ferrite is magnetic.
The stainless steel commonly used for decorative tube sheets is mostly austenitic 304 material, which is generally non magnetic or weakly magnetic. However, magnetism may also occur due to fluctuations in chemical composition or different processing conditions caused by smelting. However, this cannot be considered as counterfeit or unqualified. What is the reason for this?
As mentioned above, 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 structure can be formed in austenitic 304 stainless steel. In this way, 304 stainless steel will have weak magnetism.
In addition, after cold working, the microstructure of 304 stainless steel will also transform into 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, production Φ 76 tubes, no obvious magnetic induction, production Φ 9.5 Tube. Due to the large deformation caused by cold bending, the magnetic induction is more pronounced. The production of square rectangular tubes has a greater deformation than circular tubes, especially in the angled part, which causes more intense deformation and more pronounced magnetic induction.
To completely eliminate the magnetism of 304 steel caused by the above reasons, stable austenite structure can be restored through high-temperature solid solution treatment, thereby eliminating magnetism.
It should be pointed out that the magnetism of 304 stainless steel caused by the above reasons is completely different from that of other materials such as 430 and carbon steel, which means that the magnetism of 304 steel always shows weak magnetism.
This tells us that if stainless steel has weak magnetism or no magnetism at all, it should be classified as 304 or 316 material; If it exhibits strong magnetism similar to carbon steel, it should be distinguished as not being made of 304 material.
