Fusion Welding of Age-Hardenable Superalloys

Successful fusion welding of high strength, high temperature “superalloys” is essential to the economic manufacture of modern lightweight, high performance gas turbines. To achieve this, recognition of certain inherent problems and limitations in the welding of these alloys is vital, as the precipitation-hardened iron and nickel-based “superalloys” are intrinsically more difficult to weld than the solid solution strengthened alloys of iron, nickel, and cobalt that are also employed in gas turbine manufacture. This paper reviews the problems and some of the solutions to these problems in welding the wrought alloys A-286, alloy 718, René 41, and René 77. These alloys have been chosen for discussion both because of their wide usage in modern gas turbines and because they exemplify differing types of fusion welding problems in superalloys.