Induction kinetic welding (IKW): An innovative one-shot solid-state technique for circular joints

Abstract

In this research, an innovative solid-state joining technology has been introduced for butt-welding of circular sections with dissimilar tube and rod geometries, using induction kinetic welding (IKW). This process involves using induction to preheat material before bringing the pieces together, where rapid heating to below the base metal melting temperature followed quickly by applying axial force and shear rotation at the joint interface. A homogeneous weld microstructure consisting of refined grains and minimal heat affected zone (HAZ) is formed at the contact interface. The present work demonstrates this for a specific application involving a circular plug (with a diameter of ∼13 mm) and thin-walled tube (with a diameter of ∼13.4 mm and a wall thickness of ∼0.35 mm) both consisting of Zircaloy-4. Among the IKW processing parameters, the influence of preheating temperature and rotational shear displacement angle are the most critical inputs examined. The final joint stress distribution near the peak fracture load was modelled using finite element analysis (FEA). To this end, induction heating up to the temperature of ∼1400°C followed by a frictional shear-rotation angle of 60-degrees achieved formation of a sound solid-state weld with upset and removal of oxides from the contact interface. Afterward, the microstructural characteristics across the welding line and mechanical properties of the produced weldments were examined. A joining efficiency of 100% was achieved during the tensile fracture of the tube/plug weldment where fracture of the tube base metal has been achieved.