Inertia Friction Welding of Dissimilar Superalloys Mar-M247 and LSHR

Effect of Process Variables on the Inertia Friction Welding of Superalloys LSHR and Mar-M247

“…The yield strength of LSHR is approximately 50 pct higher as that of Mar-M247 at temperatures to 1023 K (750°C); at yet higher temperatures, Mar-M247 exhibits higher yield strength. [4,7] LSHR samples measuring 12.7-mm diameter 9 51-mm length were extracted from the center section of a 330-mm-diameter 9 51-mm-thick pancake forging using electrical discharge machining (EDM). The longitudinal direction of the extracted samples was parallel to the short transverse direction of the pancake; the end surfaces of each sample coincided with the surfaces of the forging.…”

“…The corresponding total torque T (=sum of the torque T S due to friction between the mating weld faces and the torque T M due to friction in the bearings of the IFW machine), which is associated with the deceleration of the flywheel, and the apparent friction coefficient l, were determined using the following relations: [4] T ¼ Ia; ½2…”

“…Several attempts have been made to join these types of dissimilar alloys using solid-state techniques such as friction welding. [1][2][3][4] In friction welding methods, the materials are bonded in the solid state using friction-induced heating of the mating surfaces which are brought together by an applied compression force. By this means, solidification defects associated with fusion welding techniques are avoided.…”

“…[4] The various welds exhibited two different types of mechanical behavior during post-weld tension testing [7] : (1) plastic deformation and fracture on the Mar-M247 side outside the heat-affected zone (HAZ) or (2) fracture at the weld interface. For the latter failure mode, microstructural analysis revealed defects that weakened the weld interface.…”

“…These flaws included submicron agglomerated/clustered oxide and carbide particles and/ or films at the weld interface and circumferential cracks at or near the interface on the Mar-M247 side. [4,7] The carbide and oxide particles were deduced to have been produced by friction-induced milling of large carbide particles and oxide film(s), respectively. Furthermore, particle clustering was concluded to have resulted from insufficient radial plastic flow of Mar-M247 during IFW.…”