Will stainless steel be magnetic?

Does stainless steel have magnetism, why is stainless steel magnetic?

In daily life, there are many people who know nothing about stainless steel by judging whether there is magnetism or not. Stainless steel is not magnetic, and stainless steel is stainless steel. It is stainless steel. For example, when we go to the supermarket to buy stainless steel items, the supermarket salesperson may tell you the same identification method, and even take a magnet to let you try it. In fact, this is because of the misunderstanding of the unclear concept of stainless steel. From a metallographic point of view, "steel" and "iron" are only the difference in carbon content, and have nothing to do with magnetism. In fact, common stainless steels are classified according to the characteristics of metallographic structure, and can be mainly classified into austenitic stainless steel martensitic stainless steel and ferritic stainless steel. Austenitic stainless steel is the most widely used stainless steel. Its chromium content is about 18%, and the nickel content is about 8%. It is a chrome-nickel stainless steel. It is customarily called 18-8 stainless steel. It has a low carbon content. Due to the addition of nickel, its microstructure is monocrystalline austenite at room temperature after solid-state treatment, usually without magnetic properties. However, magnetic properties may occur due to fluctuations in chemical composition or processing conditions due to smelting. For example, O304 stainless steel may have a small amount of martensite or ferrite structure due to segregation or improper heat treatment during smelting. In this way, it will have a weak magnetic.

In addition, after cold working, 304 stainless steel can precipitate a small amount of martensite structure in the steel. At this time, the steel will have certain magnetic properties, and the greater the degree of cold working deformation, the greater the magnetic properties of the steel. Martensitic stainless steel is a chrome stainless steel, which has a high carbon content and can significantly adjust its mechanical properties after heat treatment. Therefore, such steels are generally used after quenching and tempering. At room temperature, the microstructure is tempered martensite and has strong ferromagnetism, such as 1Cr13, 2Cr13, 3Cr13, 4Cr13, 7Cr13 and the like. Ferrocene stainless steel is also a chromium stainless steel, and its chromium content is generally greater than 11.5%. At room temperature, its microstructure is a single-phase ferrite structure, even if the steel is heated from room temperature to high temperature (900~1100 °C). There will be no significant changes in the organization. This type of steel also has strong ferromagnetism, representing 430 grades. From the above analysis we can see that the method of determining the stainless steel material with ferromagnetism is not correct. First, as the most commonly used austenitic stainless steel, such as 304, it is also possible to have magnetic properties. Secondly, even martensite or ferritic stainless steel may have a slightly poor corrosion resistance, but considering its price and use. The environment, as long as it is used properly, is completely corrosion-resistant and is completely stainless steel.

If the material is heated to 1850-2000 °F (1010-1093 ° C) and then water quenched, the austenitic stainless steel will completely lose its magnetic properties. But doing so will increase the cost, you don't need to do this depending on the usage!