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　　Thick wall spiral steel pipe generally have non-magnetic or weak magnetic properties, but the presence of magnetic properties will also have an impact on our use. Therefore, for many manufacturers, it is still very necessary to eliminate the magnetic properties of thick wall spiral steel pipe.

　　The reason why the thick wall spiral steel pipe is magnetic is that martensite or ferrite is magnetic, and a few martensite or ferrite arrangements in Austenitic 304 stainless steel will be formed due to component segregation or improper heat treatment during exercise. In this way, the thick wall spiral steel pipe will have weak magnetism.

　　In order to completely eliminate the magnetism of the thick wall spiral steel pipe formed by the above reasons, the stabilized austenite arrangement can be opened through high-temperature solid solution treatment, and then the magnetism can be removed. In particular, it should be pointed out that the magnetism of the thick wall spiral steel pipe formed due to the above reasons is weak compared with that of stainless steel of other raw materials, that is to say, the magnetism of the thick wall spiral tube has always been weak.

　　In addition, the arrangement structure of thick wall spiral steel pipe will also transform to martensite through cold processing. The greater the cold processing deformation, the more martensite transformation, and the greater the magnetism of thick wall spiral steel pipe. Steel strip of the same batch number, produced Φ 76 tube, no significant magnetic induction, produced Φ 9.5 pipe. The magnetic induction is significant due to the large deformation of cold bending. The deformation of square and rectangular tubes is larger than that of round tubes, especially in the angle part. The deformation of thick wall spiral steel pipe is more intense and the magnetism is more significant.

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