8-18 Stainless Steel Magnetic

Why is 304 stainless steel also magnetic? People often think that the magnet adsorption of stainless steel, to verify its superiority and authenticity, do not suck non-magnetic, that is good, the real goods; suckers have magnetic, it is considered to be impostor fake goods. In fact, this is an extremely one-sided, not practical and wrong identification method. There are many types of stainless steel, at room temperature according to the organizational structure can be divided into several categories: 1. austenitic: such as 304, 321, 316, 310, etc.; 2. martensitic or ferritic: such as 430, 420, 410, etc.; austenitic type is non-magnetic or weakly magnetic, martensitic or ferritic is magnetic. Usually used as decorative tube plate stainless steel most of the austenitic type 304 material, generally speaking, is non-magnetic or weakly magnetic, but due to smelting caused by fluctuations in the chemical composition or processing state may also appear magnetic, but this can not be considered as impostor or unqualified, this is what is the reason for it? It is mentioned above that austenite is non-magnetic or weakly magnetic, and martensite or ferrite is magnetic, due to smelting composition segregation or improper heat treatment, will cause austenitic 304 stainless steel in a small amount of martensite or ferrite organization. In this way, 304 stainless steel will have a weak magnetism. In addition, 304 stainless steel after cold working, the organizational structure will also be transformed to martensite, the greater the degree of cold working deformation, the more martensite transformation, the greater the magnetic properties of steel. As a batch number of steel strip, the production of Φ76 tube, no obvious magnetic sense, the production of Φ9.5 tube. Because of the deformation of bending larger magnetic sense is obvious, the production of square rectangular pipe because the deformation is larger than the round pipe, especially the corner part, the deformation is more intense magnetic more obvious. To completely eliminate the above reasons for the magnetism of 304 steel, through high-temperature solution treatment to restore stable austenitic organization, thereby eliminating the magnetism. In particular, the magnetic properties of 304 stainless steel caused by the above reasons, and other materials of stainless steel, such as 430, carbon steel magnetic properties are not the same level, that is to say, the magnetic properties of 304 steel is always shown as a weak magnetic properties. This tells us that if the stainless steel with weak magnetism or completely non-magnetic, should be identified as 3-4 or 316 material; if the same as the carbon steel magnetism, showing strong magnetism, due to the judgment is not 304 material.