Wire Arc Additive Manufacturing of High‐Strength Al4043 Parts Using TiN and La ₂ O ₃ as Grain Refiners

The microstructure and tensile properties of wire‐arc additively manufactured (WAAM) Al4043 with the ex situaddition of 1–8 wt.% of TiN and La ₂ O ₃ in the interlayers are studied. The grain refinement in the interlayer region ranges from 20% to 31% with TiN and La ₂ O ₃ addition compared to the pure 4043 build. Along the arm travel direction (AD), the yield strength ( σ _y ) and tensile strength of the build without grain refiners are 88 ± 7.6 and 129.2 ± 5 MPa, which increase to 89.8 ± 4.8 and 144 ± 1.6 MPa for 4043‐2La ₂ O ₃ and 102.6 ± 5 and 150 ± 2.8 MPa for 4043‐3TiN. No significant change in % elongation is observed with the addition of TiN or La ₂ O ₃ . The changes in σ _y and ultimate tensile strength are more modest along build direction, but % elongation is slightly lower compared to that along AD in all builds. Spherical cap potency model is used for theoretically predicting the grain sizes after the addition of TiN or La ₂ O _3, and the contributions to strength are also determined from grain refinement, strain hardening, and solid solution hardening models. Finally, the implications of these results are discussed in the context of further mechanical property improvements in WAAM‐fabricated Al4043.