Ultrasonic welding of ultrafine grained nickel

Abstract Solid state joints were obtained for the first time by ultrasonic welding (USW) of ultrafine-grained (UFG) thin disks of Ni processed by high pressure torsion (HPT). Samples of two types were studied: the ones for lap shear mechanical tests were prepared by joining two disks superimposed on each other under static loads of 4.5 and 6.0 kN, and the other type samples for structural characterization were obtained by sequential welding (consolidation) of four disks. The welding time for both type samples was equal to 1 s. The structure of consolidated samples was studied in their cross section by SEM, EBSD analysis, and also their Vickers microhardness was measured.