| 摘要 |
PURPOSE:To enhance the reliability in terms of strength by forming the steam chest from Cr-Mo-V steel with additional B, subjecting it to heat treatment for softening, as well as pad-welding using a welding rod made in the Cr-Mo-V composition, and thereafter welding the padding metal fast to the nozzle ring. CONSTITUTION:A steam chest 1 provided at a nozzle box, which is installed for ex. at the high-pressure first stage of a steam turbine, is formed by Cr-Mo-V steel with additional B. The steam chest 1 is subjected to a heat treatment for softening at such a temperature as to provide lower strength than the finally intended, and a pad 10 is placed at the V-groove 9 prepard in this steam chest using a welding rod made in the Cr-Mo-V composition, and finally normalized and tempered at such a temp. as to provide the intended strength. Then a nozzle ring 2 consisting, for ex., of 10 Cr steel is fabricated and welded fast to the padding metal 10 using a welding rod consisting, for ex., of 10 Cr steel. Thus the steam chest 1 and nozzle ring 2 are consolidated as in a single piece to form a turbine nozzle box. |
