Manufacturing and Properties of a Large Alloy 706 Disc Made by the Open Die Forging Process

Abstract

Kickel base alloq 706 has estensi~e application historq for rotating parts in land based gas turbines combining high strength and toughness o er the \\hole range of the sen ice temperatures. Thls material is tqpicallj finish forged in a closed die press. The size of parts needed for the land-based gas turbines is Lrerq large requiring the use of the largest forging presses in the norld. Finish forging of alloq 706 and other nickel-based alloj s for rotating parts in gas turbines require homogenous structure and properties throughout the forging. Manj evperts considered that open die forging process u ould not be able to achieve such uniformlt>. ,411 experiment mas done to determine if a \\ell-controlled open die forging process could achie e the necessarj uniformit! in microstructure and properties for a large gas turbine part made of allo~ 706 I'his paper mill describe the details of the forging and heat treatment process. Results of mechanical tests and metallographic examination \+ill be also discussed. Issues with process control and repeatability for open die forging are also discussed.