Microstructure, mechanical properties and deformation behavior of laser additively repaired 5083 and 6061 Al alloys utilizing AlMgScZr powders

Laser additive repair (LAR), as an efficient repair method, lacks specialized repair materials for Al alloys. In this work, the high-strength AlMgScZr powder was employed to address the scarcity of specialized materials and the issue of inadequate performance in LAR of 5083-H112/6061-T6 Al alloy. The microstructure, mechanical properties and deformation behavior of repaired specimens were studied. The repair zone (RZ) had high strength and high density, and the porosity was as low as 0.12 %. There was good compatibility between the repair material and the base metal (BM), and good metallurgical bonding was achieved at the fusion line. The microstructure and strengthening phase (T-phase) in the heat affected zone (HAZ) of the 5083 repaired parts exhibited negligible changes, there was no deterioration in mechanical properties. The yield strength was 162 MPa, tensile strength was 291 MPa, and elongation was 16.2 %, reaching 94 %, 104 %, and 70 % of the BM, respectively. The mechanical properties are superior in the current research on LAR of Al alloys. The LAR technique showcases its versatility in repairing aging non-strengthening Al alloys. The transition of β′′→β′ (or with B′/U1/U2)→β of the nano-reinforced phase resulted in deteriorative mechanical properties of HAZ in the 6061 repair part, consequently, the tensile strength of 6061 repair part was only 63.8 % of the strength of BM. After solution aging treatment, the β′′ phase in HAZ re-precipitated, effectively restoring the strength of 6061 repaired parts. The tensile strength of the repaired parts was increased to 95.2 % of the strength of BM. The present study elucidates the evolution of microstructure and mechanical properties during LAR process of Al alloys, offering valuable insights for future applications of this technology on Al alloys.