In-situ analysis on tensile deformation behavior of impact welding joint

Abstract

As a solid-state impact welding technique, magnetic pulse welding has previously been applied in aircraft flight control tubes, end enclosures for nuclear fuel rods, automotive transmission shafts, etc. However, current reports focus on optimizing the manufacturing process to achieve superior mechanical properties of the joints, neglecting their dynamic response under stress. This study provides the first insights into the synergistic deformation effects of the welding zone characteristics and multiscale interface microstructure of an Al/Fe magnetic pulse welded joint under sustained loading. An innovative combination of in-situ Digital image correlation and Smooth particle hydrodynamics simulation confirms the asynchronous deformation behavior and significant strain localization in the welded zones. In-situ observations show that the waveform intermetallic compounds layer causes delay in the crack propagation originating from the weakly bonded zone by absorbing deformation energy and increasing the crack propagation path. Finally, interface cracks are hindered by the waveform interlocking interface and are deflected into the Al sheet. The combined presence of Al-Fe coherent interfaces within vortex zones, nanoscale intermetallic compounds in intermediate pockets, and amorphous layers contributes to the excellent welding strength of the waveform-interlocking interface. In addition, molecular dynamics simulation results demonstrate that dislocations originating from Fe atoms propagate into the amorphous layer, thus promoting the emission of pre-existing dislocations into Al atoms and effectively reducing the rapid stress concentration at the interface. These findings fill a gap in current research on the mechanical properties of magnetic pulse welded joints and provide valuable insights for optimizing the joint interface microstructure.