Interfacial bonding behaviours of AA5052/DC05 in synchronous thermomechanical joining-forming process

Abstract

The reliable simultaneous joining and forming of dissimilar metallic sheet-structural components consisting of aluminum (Al) alloy and steel (St) sheets remains challenging, especially within one integrated process. A recently-established joining-forming concept, described as friction stir-assisted incremental forming and synchronous bonding, has become a promising process to obtain well-bonded and deformed Al-St hybrid sheet-structural products. In the current study, an updated finite element model is established to reveal the interfacial bonding behaviours of Al-St hybrid structures. Heat generation, heat flux transfer, and interacted behaviours at the dissimilar interface are investigated through the established heat-coupled contact framework. A newly pressure-strain-temperature dependent bonding criterion is proposed to evaluate the behaviour of interfacial elements on tangential and normal relative motion. Cyclic double-sided squeezed loading within the high-temperature range (>350 °C) can improve coordinated plastic deformation of the Al-St interface, resulting in high bonding quality. A heat-coupled contact subroutine simulation framework provides good insight into understanding the solid-state bonding of the Al-St joint during thermomechanical deformation and could be an applied solution for joining-forming other dissimilar materials.