A HIGH STRENGTH STEAM TURBINE ROTOR AND METHODS OF FABRICATING THE ROTOR WITHOUT INCREASED STRESS CORROSION CRACKING

摘要

PURPOSE: A method of fabricating rotor without increased stress corrosion cracking is provided to produce a monoblock, low alloy steel rotor for use in low pressure steam turbines. CONSTITUTION: The method includes austenitizing the rotor at a substantially uniformly applied treatment temperature of about 840deg.C, quenching the rotor, and then differentially tempering the rotor at different axial locations. The rotor is tempered in a furnace divided into regions by refractory boards enabling different temperatures in each divided region to be maintained. A higher condition than normal strength is achieved in one or more axial locations along the rotor by subjecting the location(s) to a lower tempering temperature. The axial location(s) is tempered at lower temperature approximate those locations less susceptible to stress corrosion cracking whereby increased strength is provided to the rotor without increasing net susceptibility to stress corrosion cracking.