Mixed INCONEL® alloy 718 inertia welds for rotating applications -: Microstructures and mechanical properties

IN718 is the work-horse nickel-iron-chromium alloy for a variety of parts for aero-engine applications such as disks, shafts, blades, vanes, casings and fasteners due to a good combination of relevant mechanical properties, good corrosion resistance, easy fabricability and reasonable cost. The conditions in aero-engines often require joining rotating parts which are made out of different materials, for example due to temperature limitations of one material. Besides the possibility of bolting the parts together, welding can lead to some advantages and is used in the compressor and high-pressure turbine section of aero-engines. For joining nickel-super-alloys and especially different nickel-alloys inertia welding represents often the only available possibility. The following work summarizes investigations of inertia welding IN718 with alloys INCOLOY (R) alloy 909, UDIMET (R) 720LI, Rene (R) 88DT and itself. The influence of various post-weld heat-treatments on the microstructure and some relevant mechanical properties as tensile and low cycle fatigue properties is described. The focus in this work is on the IN718 part of the investigated weld.