What is 304 Stainless Steel
Grade 304 is a classic 18% chromium, 8% nickel austenitic stainless steel. It's an all-purpose product with good corrosion resistance and is suitable for a wide variety of applications that require good formability and weldability.The chromium and nickel alloys in 304 make it resistant to many corrosion attacks.
In addition,304 stainless is widely used in a wide range of industries since it does not need a post-weld anneal (a reheating and cooling process that relieves metals of heat-induced stress). Grade 304 stainless steel is made up of 16-24% chromium, as well as alloys such as nickel, carbon, and manganese. 304 Steel has excellent corrosion resistance,making it suitable for most food applications.
Is 304 Stainless Steel Magnetic?
304 stainless steel is a common austenitic stainless steel. The internal structure is mainly austenite. This type of stainless steel is usually non-magnetic or a little magnetic.However, in practical applications, it may be found that 304 stainless steel has certain magnetism.
The majority of Austenitic stainless steels are non-magnetic due to high levels of austenite.Despite the fact that some of the alloys, such as grades 304 and 316, contain iron, these materials are non-ferromagnetic. It is the crystal structure that is important for magnetic properties.
What makes 304 stainless steel magnetic?
All stainless steel is magnetic except austenitic stainless steel which is actually 300 series stainless such as 304 and 316.However, 300 series stainless is non-magnetic only after it is freshly formed. 304 is almost for sure to become magnetic after cold work such as pressing, blasting, cutting, etc.Initially the cold work causes the stainless to pick up foreign particles such as free iron. Then at some spots the metallic crystal structure changes from austenite to martensite.
The austenitic stainless steel grade 304 is not magnetic but it may become a little magnetic in areas that have been cold working (bending, deforming, etc.).
- During the smelting process of austenitic stainless steel, due to component segregation or improper heat treatment, a small amount of martensite or ferrite may appear,which have magnetic crystal structures,making 304 stainless steel will have a certain magnetic.
- In addition,during cold working processes such as cold rolling, stamping, and bending,304 stainless steel undergoes deformation of austenite grains and stress concentration,causing to the transformation of part austenite into martensite. The higher the content of martensite, the stronger the magnetic properties.
- Chemical composition fluctuations during smelting process.Due to the difficulty in controlling the content of various elements during the smelting process,trace amount of martensite or ferrite structures may appear in 304 stainless steel,which are both magnetic crystal structures,can impart little magnetic to 304 stainless steel.
How to eliminate magnetism of 304 steel?
To eliminate the magnetism on 304 stainless steel, a high-temperature treatment can be used to restore stable austenite structure to eliminate the magnetic properties.
- High temperature solution treatment.Heating 304 stainless steel to about 1050°C,holding it for a certain period, and then rapidly cooling it can completely restore the austenite structure,eliminating the presence of martensite or ferrite,and then removing the magnetic.
- Annealing treatment. Heating 304 stainless steel to about 800°C, maintaining it for a certain period of time, and then cooling it slowly can partially restore the austenite and reduce the content of martensite or ferrite, to reduce the magnetism.
- Magnetic field processing. Placing 304 stainless steel in a strong magnetic field can make its magnetism weaken or disappear by changing the arrangement direction of its internal magnetic domains.
If you'd like to discuss your requirements, JBLSTEEL have a team of experts who are able to assess your business needs relating to your project and help you select the right material for you. If you'd like to book a free consultation, pre-audit site survey or equipment testing, click here.
