Effect of annealing mode of cold-rolled sheets on the structure and mechanical properties of Al – 1.5% Cu – 1.5% Mn(Mg, Zn) alloy

The effect of annealing modes on the structure and mechanical properties of Al – 1.5 Cu – 1.5 Mn alloys with different magnesium and zinc content was studied using cold-rolled sheets as an example. At the first stage, flat ingots measuring 20×140×180 mm were obtained by casting into a graphite mold from three experimental alloys: Al – 1.5 Cu – 1.5 Mn, Al – 1.5 Cu – 1.5 Mn – 0.5 Mg – 1,0 Zn and Al – 1.5 Cu – 1.5 Mn – 1,0 Mg – 1,0 Zn. Then, hot-rolled sheets with a thickness of 4 mm were obtained from these ingots by hot rolling at a temperature of 450 oC, which were then annealed at a temperature of 350 oC for 3 hours, after which cold rolling was performed to a thickness of 1 mm. The microstructure of the samples cut from the ingots and sheets was studied using light and electron scanning microscopes. In order to evaluate the effect of heat treatment on the structure and physical and mechanical properties, multi-stage annealing of sheets and ingots of experimental alloys was performed in the temperature range from 400 to 500 oC with a step of 50 oC with cooling in a furnace and outside it. Mechanical properties (ultimate strength, yield strength and relative elongation) of cold-rolled sheets were determined by tensile testing on a universal machine. It was shown that to increase the strength of annealed cold-rolled sheets of the base alloy, it is sufficient to add magnesium in an amount of 0.5%, while the permissible concentration of zinc can be increased to at least 1.3%. The combined addition of magnesium and zinc in various ratios to the base alloy Al – 1.5 Cu – 1.5 Mn allows to significantly increase the strength properties of annealed cold-rolled sheets even with slow cooling, which is comparable with the cooling of coils under industrial production conditions.The work was supported by the Russian Science Foundation grant No. RSF 20-19-00249-P.