Product Application and Classification
Retaining ring, one of retaining ring forgings, is the critical component of the turbine engine. It is non-magnetic and metal-ring component which is used to fix and keep rotor end windings overcoming high strength of the centrifugal force. The retaining ring must be made of non-magnetic material in order to avoid the loss of alternating magnetic field.
There are 1Mn18Cr18N, 50Mn18Cr5 and 50Mn18Cr4WN according to material. There are 25MW, 60MW, 125WM, 300WM, 600MW and 1000MW specifications according to installed capacity.
Our company has begun to develop and produce retaining ring and forging metal since 1970s, and successively adopted half hot forging, spherical punch reaming, explosive forming and other deformation strengthening processes. The company began to study the hydraulic bulging strengthening method to produce retaining rings in the late 1980s. NHI was successful to develop special press of retaining ring production. And the process principle of the special press is outside fluid added and hydraulic bulging strengthening method. In the beginning, the material of retaining ring included 50Mn18Cr5, 50Mn18Cr4WN. The specification was below 200MW, and the annual output is about 300 pieces. The production of 1Mn18Cr18N retaining ring was started after 2000. NHI has manufactured more than 6000 various retaining rings including 50Mn18Cr5, 50Mn18Cr4WN, 1Mn18Cr18N (referred to the "double 18"), in which "double 18" retaining rings reached more than 800 pieces, and there are 20 specifications from 3MW to 1000MW, at the same time, the strength of products reached Level 8 of ASTM A289 and the yield strength was 1430MPa. The products are widely used in many domestic generator equipment manufacturers, and are exported to Brazil, India and other countries.