? ? ? ? ?People often use magnet to absorb stainless steel, and verify their advantages and disadvantages. They don't smoke without magnetism. They think they are good and they are genuine. When they are magnetic, they think they are fakes. In fact, this is a very one-sided, unrealistic, wrong way to distinguish.
There are many kinds of stainless steel. They can be divided into several groups according to the organizational structure at normal temperature:
1, the Austrian type: such as 304, 321, 316L, 310S and so on;
2, martensite or ferrite type: such as 430, 420, 409L, 410 and so on;
? ? ? ? The austenite is nonmagnetic, or if magnetic, martensite or ferrite is magnetic.
? ? ? ? ?Usually do most decorated with stainless steel is Austenitic 304 material, generally speaking is "magnetic" or if magnetic, but fluctuations in chemical composition caused by smelting or processing of different magnetic properties may also appear, but this can not be considered to be counterfeit or substandard, what is the reason?
? ? ? ? The above mentioned austenite is "non-magnetic" or if the magnetic properties and martensite or ferrite is magnetic, because when smelting segregation or other reasons, will cause a small amount of iron martensite or ferrite microstructure appeared in 304 austenitic stainless steel. Such. 304 stainless steel will have a weak magnetic.
? ? ? ? ?In addition, 304 stainless steel after cold processing, the organizational structure will also be converted to martensite, cold processing deformation greater, the more martensitic transformation, the greater the magnetic properties of steel. Like a lot of the strip, with 76 production tube, no obvious induction, Phi 9.5 tube production, because of cold bending deformation of large induction is obvious, the production of rectangular pipe for volume than the cylinder, especially the bending angle, the magnetic properties of more intense deformation is more obvious.
? ? ? ? ?In order to completely eliminate the magnetic properties of the 304 stainless steel caused by the above reasons, the stable austenite structure can be recovered by high temperature solution treatment so as to eliminate magnetism. Therefore, it is one-sided to judge the authenticity of 304 by mere magnetism.
? ? ? ? ?For a long time, many people will not judge the material is stainless steel with a magnet, that stainless steel is not magnetic, not magnetic stainless steel has no effect on the problem, but this kind of stainless steel with or without magnetic facts. Different products have different requirements, can not take orders that stainless steel is magnetic, that is not good, electronic components with magnetic is not good, but refrigerators, magnetic door and induction cooker must be magnetic. In addition, the magnetic stainless steel in Zhengzhou is not corrosion statement, is also extremely wrong. Japan is a coastal country, but most of their products are made of stainless iron, because of environmental protection and corrosion resistance, some brands of stainless steel, rust resistance than non magnetic austenitic stainless steel is ok. In daily life, there are many people who have a smattering of stainless steel to judge stainless steel by whether or not they are magnetic. Without magnetism, they are stainless steel. The magnetic ones are not stainless steel, and they are stainless steel. For example, ? ? ? ? ?when we go to the supermarket to buy stainless steel items, the supermarket salesman may tell you the same identification method, and even take a magnet out, let you try your eyes.
? ? ? ? ?In fact, this is because of the concept of stainless steel is not clear and another misunderstanding.
? ? ? ? ?From the point of view of metallurgy, "steel" and "iron" only depend on the difference in carbon content, and have nothing to do with magnetism. In fact, the common stainless steels are classified according to the characteristics of metallographic structure, which can be divided into three categories: austenitic stainless steel, martensitic stainless steel and ferritic stainless steel.
? ? ? ? ?Austenitic stainless steel is a wide range of applications of stainless steel, its chromium content is about 18%, containing nickel content of about 8%, belonging to chromium nickel stainless steel, used to be called "18-8 type stainless steel". The carbon content of it is low, because of the added nickel, after solid Fu after treatment at room temperature, the microstructure is austenite, usually is not magnetic. But because of the chemical composition fluctuation or processing state is different, there may be magnetic. Such as 304 stainless steel, due to segregation or improper heat treatment during smelting, there will be a small amount of martensite or ferrite structure. In this way, it will have a weak magnetism. In addition, after 304 stainless steel after cold processing, a small amount of martensite can be precipitated in the steel. At this time, the steel will have a certain degree of magnetism, and the greater the deformation degree of cold working, the greater the magnetic properties of steel.
? ? ? ? ?Martensitic stainless steel belongs to chromium stainless steel, its carbon content is higher, it can significantly adjust its mechanical properties after heat treatment. Therefore, this kind of steel is usually quenched and tempered before use. At room temperature, the microstructure is tempered martensite with strong ferromagnetism, such as 1Cr13, 2Cr13, 3Cr13, 4Cr13, 7Cr13 and so on.
? ? ? ? ?Ferritic stainless steel is Hugh chromium stainless steel, the chromium content is generally greater than 11.5%, room temperature, the microstructure of single-phase ferrite Hugh, even if the steel heating from room temperature to high temperature (900~1100 DEG C). The organization did not change significantly. This kind of steel also has a strong ferromagnetism, the number of representatives of 430.
? ? ? ? ?From the above analysis we can see that it is not correct to judge whether stainless steel is ferromagnetic. First of all, as a commonly used austenitic stainless steel, such as 304, then it is possible, even if it is magnetic, martensite or ferrite stainless steel and its corrosion resistance may be slightly worse, but considering the price and the use of the environment, if used properly, but also can be completely corrosion resistant, stainless steel answer: stainless steel with its beautiful appearance, corrosion resistant properties, is not easy to damage the advantages of more and more popular. Some customers in the purchase of stainless steel, holding a magnet on the stainless steel suction. That the magnet is on the stainless iron, not stainless steel, stainless steel are not magnetic. In fact, this
