Enhancing strength and ductility synergy of laminated aluminum composite 2024 / 5154 through cold roll bonding combined with heat treatment

One of the most important objectives in the fabrication of laminated metal composites (LMCs) is to ensure a high level of both service and mechanical properties. On an industrial scale, LMCs is produced using the known processes of accumulative roll bonding or cold / hot roll bonding. Large degrees of deformation typical for these processes inevitably lead to an increase in strength and a sharp decrease in ductility, which significantly limits the practical applications of LMCs. 2024 / 5154 aluminum alloy-based composite studied in the current work, offers, on the one hand, high strength of 2024 alloy and, on the other hand, high corrosion resistance, weldability, and hardness of 5154 alloy. During experimental fabrication of 2024 / 5154 composites by cold roll bonding process, it was found that an increase in thickness reductions in combination with recovery annealing leads to a gradual increase in strength characteristics and a decrease in ductility compared to the starting materials. Applying directly opposite heat treatment effects to the composite components, in which 2024 alloy is heat-treatable and 5154 alloy is non-heat-treatable, opens up fundamentally new possibilities. As was experimentally revealed, the combination of cold deformation with post-heat treatment of 2024 / 5154 composite led to an increase in both the ultimate tensile strength (up to 287 MPa) and elongation at fracture (up to 35 %) in comparison with the starting materials, weighted average ultimate tensile strength of which was 223 MPa and weighted average elongation at fracture was 31 %. Examination of the microstructure using an optical microscope made it possible to assess changes in the grain size of the composite after aging treatment compared to the starting materials. Analysis of the microhardness distribution across the sheet thickness revealed successful hardening of the inner layer from 2024 alloy and softening of the outer layers from 5154 alloy.

1. Ministry of Science and Higher Education of the Russian Federation (Russia) - The state assignment 124020800027-4