Forging for advanced trubine applications: Development of multiple alloy rotor forging for turbine application

Abstract

Two large integral multiple alloy rotor (MAR) forgings have been successfully produced to provide an alternative to welded rotor construction for advanced turbine applications. Each single piece forging comprises a CrMoV steel intermediate pressure (IP) section and a NiCrMoV low pressure (LP) section. Special production techniques, tooling, and control methods were developed to optimize the manufacture of multi-alloy electrodes, electroslag remelting (ESR), forging, differential heat treatment and inspection. This helped attain accurate control of the chemical transition zone location, width and symmetry and lead to achievement of all mechanical properties, inspection goals and thermal stability requirement.