The magnetic permeability of austenitic stainless steel is very small, so it is also called non-magnetic material. Steels with stable austenite structure, such as 0Cr 20 Ni 10, 0Cr 25 Ni 20, will not be magnetic even if they are processed with large deformation greater than 80%. In addition, high carbon, high nitrogen and high manganese austenitic stainless steel, such as 1Cr17Mn6NiSN, 1Cr18Mn8Ni5N series and high manganese austenitic stainless steel, will occur under large reduction processing conditions ε Phase change, so it remains nonmagnetic. At high temperatures above the Curie point, even strong magnetic materials will lose their magnetism. However, some austenitic stainless steels, such as 1Cr17Ni7 and 0Cr18Ni9, will undergo martensitic transformation during large reduction cold processing or low temperature processing because of its metastable austenite structure, which will have magnetic properties and magnetic permeability.