Abstract
Abstract Al–Li alloy has been widely used in the aerospace field owing to its high strength and low density. In this study, alternating current cold metal transfer (AC CMT) along with a high-frequency pulse current technique was used to weld a 2060 Al–Li alloy using an ER5356 wire. The effect of pulse frequency on the arc shape, microstructure, and mechanical properties of the welded joints was examined, and mechanical performance testing was conducted. The results revealed that the arc diameter, arc length, and arc volume showed a trend of increasing first and then decreasing with an increase in the pulse frequency and reached their peak values when the pulse frequency was 50 kHz. Coupling the welding process with a high-frequency pulse resulted in grain refinement, which was attributed to the stirring action of the arc force. Both the porosity levels and grain size decreased with increasing frequency. When the pulse frequency was 70 kHz, the porosity level was the lowest, and the grain size was refined to 24.1 μm. The tensile strength of the welded joints also increased with the pulse frequency, and a maximum tensile strength of 249 MPa was observed at 70 kHz.
Highlights
Owing to the advantages of low density, excellent resistance to stress corrosion cracking, and enhanced mechanical properties such as high strength and good fracture toughness, Al–Li-based alloys are widely used in aircraft and aerospace structures
Mousavi and Sabzi [5] studied the effect of pouring temperature and the surface angle of vortex casting on the microstructural evolution and mechanical properties of 7050 Al–3wt% SiC composite
Research on the excellent combination of alternating current cold metal transfer (AC Cold metal transfer (CMT)) and high-frequency pulse current for welding 2060 Al–Li alloy can provide a reference for the preparation of aerospace structural parts
Summary
Owing to the advantages of low density, excellent resistance to stress corrosion cracking, and enhanced mechanical properties such as high strength and good fracture toughness, Al–Li-based alloys are widely used in aircraft and aerospace structures. Recent studies on arc welding have demonstrated the positive effect of impulse current and frequency in grain refinement during the solidification of the weld region in aluminum alloys. During alternating current (AC) arc welding, the coupling of a high-frequency and moderate pulse current frequency has significant effects on the solidification process of the molten metal [8] This has often resulted in improved mechanical properties of weld joints. This study chose a new process that combines high-frequency pulse current with an AC CMT welding process to weld aluminum–lithium alloys This process has been used to weld 2198 Al–Li alloy and has achieved good results. Research on the excellent combination of AC CMT and high-frequency pulse current for welding 2060 Al–Li alloy can provide a reference for the preparation of aerospace structural parts
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