Spot lap joining of AA5052 to AISI 1006 by aluminium extrusion via friction forming technique

Abstract

Purpose The purpose of this paper is to join AA5052 to AISI 1006 steel sheets using the spot friction forming technique. Design/methodology/approach A steel sheet was pre-holed with a diameter of 4.8 mm and pre-threaded with a single internal M6 thread. Lap joint configuration was used so that the aluminium specimen was put over steel. A rotating tool with a 10 mm diameter was used for the joining process. A Taguchi method was used to design three process parameters (plunging tool depth, rotating speed and preheating time), with three levels for each parameter. The effect of the process parameters on the joint shear strength was analysed. The macrostructure, microstructure and scanning electron microscope of the joint were investigated. The temperature distribution during the joining process was recorded. Findings The formed aluminium was extruded through the steel hole and penetrated through the thread slot. A mechanical interlock was achieved between the extruded aluminium and the steel. The plunging depth of the tool exhibited a significant effect on the joint shear strength. The joint efficiency increased gradually as the plunging depth increased. Two modes of failure were found shear and pull-out. The maximum temperature during the process reached 50 per cent of aluminium’s melting point. Originality/value For the first time, AA5052 was joined with AISI 1006 steel using a friction spot forming technique with an excellent joint efficiency.