Microstructural characterization and mechanical performance of Al–Cu–Li alloy electron beam welded joint

Abstract

Al–Cu–Li alloy with the thickness of 4 mm is welded by electron beam welding (EBW). Microstructure and mechanical properties of welded joint are systematically investigated. The formation mechanism of weld porosity is fully discussed. Orthogonal experiment results show that welding parameters have great effect on the generation of weld gas pore, and welding speed is the main factor affecting the porosity, followed by electron beam scanning mode, electron beam current is the minimal one. Microstructure analysis demonstrates that weldment is mainly equiaxed grains, and some dendrites exist too. Mechanical properties of welded joints indicate that, under the following welding parameters, electron beam current 13 mA, welding speed 600 mm/min, circular electron beam scanning, a welded joint with good mechanical performance can be obtained. Tensile strength of welded joint is 368.4 MPa, which is about 68% of that of the base metal (BM). SEM analysis shows that there are many fine dimples distributed on the fracture surface of welded joint, and it obviously presents the characteristic of ductile fracture.