A Study on the Magnetic Permeability of Austenitic Stainless Steel in the Large-Scale Electrophysical Devices

With the progress of the large-scale scientific facilities, the vacuum system and the stability of materials have shown the need for a higher level of reliability to ensure the stable operation of the beam and provide an ultrahigh vacuum environment. The key component such as the vacuum vessel of the Tokamak fusion experimental reactor, has a high requirement for its relative magnetic permeability, and the steel used must meet the relative magnetic permeability of less than 1.05 or even 1.03; therefore, the control of the magnetic permeability is of great significance for the development of nuclear fusion testing devices and various accelerators. This article conducts research on the issue of magnetic permeability exceeding standards in engineering applications of 316L (N) austenitic stainless steel plates, bolts, and other components. It is found that nickel element composition plays a decisive role in controlling magnetic permeability. In addition, bolts with relative magnetic permeability exceeding standards were demagnetized at 1050 °C, and it was found that their magnetic permeability was controlled, but their sealing performance decreased.