40Mn18Cr3 is non-magnetic austenitic chromium-manganese retaining ring steel after solution treatment, semi-hot or cold deformation strengthening deformation strengthening to improve the strength of steel to meet the different categories of retaining rings. Retaining ring for category class Ⅰ ~ Ⅲ the turbogenerator nonmagnetic retaining ring forgings and other requirements of non-magnetic components.