In our subconscious mind, we always think that 304 stainless steel bolts and 316 stainless steel bolts are nonmagnetic, and many users judge the quality of stainless steel bolts by the presence or absence of magnetism when using stainless steel bolts. They think that the nonmagnetic ones are authentic stainless steel bolts, while the magnetic ones are of poor quality. Here, Xiaorui said responsibly that this was wrong!
Why not? We know that the materials used to produce stainless steel bolts begin with the word "austenitic 3", such as SUS304 and SUS316. For stainless steel bolts used for production of self tapping and self drilling, it starts with the word "Martens 4", such as SUS410. The 410 material has more carbon, so it will be magnetic. The reason for this self magnetism is to increase the hardness of the self tapping screw, otherwise it will not be able to penetrate. Therefore, it is normal for 410 material to be magnetic.
Now let's talk about the magnetism of SUS304 and SUS316 stainless steel bolts. In theory, austenitic stainless steel bolts are nonmagnetic or weak magnetic. However, after cold pier processing, both SUS304 stainless steel bolts and SUS316 stainless steel bolts will have some magnetism, which has nothing to do with the quality of the materials, but because the materials are magnetic after cold processing. Such problems have no impact on the performance and use function of stainless steel bolts. If there are some electronic circuit boards that require stainless steel bolts to be free of any magnetism, we can also demagnetize the stainless steel bolts. After demagnetization, the stainless steel bolts can be completely demagnetized. At present, there are two ways of demagnetization. One is physical demagnetization, and the other principle is similar to centrifugal demagnetization. However, it is not kept for a long time, and the magnetism will recover. The other is solution treatment, which is a relatively firm demagnetization method. After solution treatment, stainless steel bolts can be completely demagnetized, and will not recover magnetism.
If it is a stainless steel bolt product processed by turning, the carbon content in its material is higher. The material used is SU303. It must have magnetism, but its rust resistance is no different from SUS304. In many application fields, in order to solve the actual product use requirements, some optimization and modification are made to the parameters of stainless steel bolts to improve the success rate of the solution, Only some different design references can be made on materials.
