Development of Fe-13%Ni-1.5%Mo Alloy for Ferromagnetic Field Winding Support Shaft of Superconducting Generator

Abstract

Fe-13%Ni-Mo alloy is investigated in order to develop ferromagnetic field winding support shaft of superconducting generator. Solidification test and solidification simulation show that reducing Mo content of the alloy to 1.5% and selecting 1050mm-diameter electroslag remelting process is necessary to avoid harmful macro segregation in the ingot. A trial forging of Fe-13%Ni-1.5%Mo alloy having identical cross section of ferromagnetic field winding support shaft of 200MW machine is manufactured from 1050mm-diameter ingot. A series of test proves that it has no harmful macro segregation and has appropriate properties, that is, stable fracture toughness down to 4K, ferromagnetic property with high flux density, good machinability and weldability. An example of electrical design of 200MW machine shows that the ferromagnetic field winding support shaft can improve output density, efficiency and stability of electrical power system as compared to conventional nonmagnetic one.