Microstructure and tensile properties of 5356 aluminum alloy by TIG wire arc additive manufacturing

The microstructure and properties of 5 356 aluminum alloy sample manufactured by TIG wire arc additive manufacturing in the different regions were studied. The results showed that interlayer of sample alternated with the deposition layer horizontally, the width of deposition layer at the bottom was the largest (~2.4 mm), and the middle stable region was the smallest (~1.6 mm). The deposition layer consisted of equiaxial grains, and the black second phase β-Al₃Mg₂ and a small amount of intermetallic compounds Mg₂Si and (FeMn)Al₆ diffused on the gray matrix. A large number of pores and shrinkage holes appeared at the interlayer. The deposition layer at the bottom had the smallest grain size, but the interlayer had the most defects. The strength and plasticity were approximately equal in the horizontal direction at the different regions (R_\rmm = 274\;\rmMPa, \;A = 32.3\%). The strength in vertical direction was approximately equal to that in horizontal direction, but the elongation dropped to 26%. The tensile fracture was mainly composed of equiaxial dimples in both directions. The hardness of the deposition layer at the three regions was stable, and the hardness at the bottom was slightly higher than that of the rest regions, while the hardness of the interlayer fluctuated significantly.