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Why is stainless steel magnetic?

Why is stainless steel magnetic?

Time:2022-03-18 Source:China Wuxi JiaNuo Special Steel Co.

Why is stainless steel magnetic?

Many people often think that the magnet adsorbs stainless steel material, to verify its merits and authenticity, does not suck no magnetic, think it is good, the real thing; suckers have magnetic, it is considered counterfeit counterfeit. In fact, not practical and wrong identification method.

First of all, we need to understand the stainless steel, stainless steel, a wide range of types, at room temperature, according to the organizational structure can be divided into several categories.

Austenitic type: such as 201, 202, 301, 304, 316, etc.

Martensitic or ferritic type: such as 430, 420, 410, etc.

Austenitic type is non-magnetic or weakly magnetic, martensitic or ferritic is magnetic.

Most of the stainless steel usually used as decorative tubes is austenitic type 304 material, generally speaking, is non-magnetic or weakly magnetic, but should be manufacturers smelting caused by fluctuations in chemical composition or processing state may also appear magnetic, but this can not be considered counterfeit or substandard.

Above mentioned austenite is non-magnetic or weakly magnetic, while martensite or ferrite is magnetic, due to smelting composition bias or stainless steel tube factory improper heat treatment, will cause austenite 304 stainless steel in a small amount of martensite or ferrite organization. In this way, 304 stainless steel with a weak magnetic properties.

In addition, 304 stainless steel after cold processing, the organizational structure will also be transformed to martensite, the greater the degree of cold processing deformation, the more martensite transformation, the greater the magnetic properties of steel. Such as the same batch number of steel pipe, the production of OD 76 stainless steel pipe, no obvious magnetic sense, the production of OD 9.5 stainless steel pipe. Because of the larger magnetic sense of cold-drawn deformation is obvious some, the production of square rectangular tube because of the deformation than the round tube, especially the corner part, the deformation is more intense magnetic more obvious. To completely eliminate the above reasons for the magnetic properties of 304 stainless steel, can be opened by high temperature solution treatment to restore stable austenite organization, thus eliminating the magnetic properties.

In particular, the above reasons for the magnetic properties of 304 stainless steel, and other materials of stainless steel, such as 430 stainless steel, carbon steel, magnetic properties are not at all the same level, that is to say, 304 stainless steel tube magnetism is always weak magnetic. This tells us that if the stainless steel tube is weakly magnetic or completely non-magnetic, should be judged as 304 or 316 stainless steel material; if the same as the magnetic properties of carbon steel, showing strong magnetic properties, because the judgment is not 304 material, this statement is wrong. General discriminate the need for professional institutions to detect, such as chemical potion detection or spectral analysis.