Extending the Size of Alloy 718 Rotating Components

Abstract

Alloy 718 rotors, in previously unheard of sizes, have been introduced into GE heavy-duty gas turbines. The forged area of each disk in a rotor is an order of magnitude larger than those of aircraft engine disks. The production challenges posed by the very large 718 ingots and forgings needed to make the rotors are discussed in this paper. The issues include segregation, abnormal grain growth and processing limitations imposed by the size of production equipment.

Recent developments in gas turbine materials and technology and their implications for syngas firing

“…Consequently, successful fabrication of large forgings from Ni-base alloys required a significant development effort (see, for instance, reports from General Electric's program, Refs. [27][28][29][30]), which was focused on four main requirements, viz…”

Closed Die Hammer Forging of Inconel 718

“…In the present study, closed die hammer forging was employed due to nonavailability of large press. Even though published work is available on development of large forgings, it is mostly confined to processing using press [3][4][5]. There are no reports on production of IN-718 hemispherical domes by closed die hammer forging or press forging in open literature.…”

Application of Confocal Scanning Laser Microscope in Studying Solidification Behavior of Alloy 718

“…With the development of land-based power generation and aircraft propulsion, scaling-up of components has become the necessity. In response to market demands the size of Alloy 718 ingot produced by VIM-ESR-VAR triple melting has increased markedly over the past 10 years [2][3][4][5][6][7]. However, the solutes segregation problem, mainly niobium segregation, is a big issue for producing large size Alloy 718 ingots.…”