Microstructure and Mechanical Properties of 2024 Aluminum Alloy Prepared by Wire Arc Additive Manufacturing
Owing to its outstanding advantages,such as low specific gravity,high specific strength,and good machinability,2024 aluminum alloy has been used as various load components in the aero-space field and has become an important lightweight material.The properties of the 2024 aluminum alloy are highly correlated with its microstructures.Accordingly,in this study,2024 aluminum alloy deposited specimens were fabricated using wire arc additive manufacturing.Further,the microstructures and me-chanical properties of the deposited specimens were investigated in different regions.The layered charac-teristics could be observed macroscopically in the deposited specimens,and a single deposition layer was divided into two regions:interlayer and innerlayer.The grain morphology changed from equiaxed grains in the innerlayer region to columnar grains in the interlayer region.The deposited specimens main-ly included α-Al,θ-Al2Cu,and S-Al2CuMg phases.In the nonequilibrium solidification process of additive manufacturing,the deposited specimens presented element segregation.The distribution of Mg in the Al matrix was uniform for the innerlayer region.However,Cu was segregated as eutectics at the grain boundary in the interlayer region.The average tensile strength,yield strength,and elongation of deposit-ed specimens were(323.5±6.6)MPa,(178.7±6.2)MPa,and(9.03±0.67)％,respectively,which were higher than those of cast annealing 2024 aluminum alloy.Owing to the difference in the microstructure,the innerlayer and interlayer regions showed different crack propagation behavior.The cracks in the inter-layer region propagated along the distribution path of eutectics,showing intergranular fracture,and the crack propagation mode in the innerlayer region changed to transgranular fracture.
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