Strength and substructure of Al–4.7Mg–0.32Mn–0.21Sc–0.09Zr alloy sheets

Abstract

Laws of the formation of substructure and of changes in the hardness and in the mechanical properties have been established for sheets of 1545K alloy obtained by tension according to different technologies at various accumulated strains. With an increase in cold deformation (e_cold) from 0 to 2.64, the yield stress of cold-worked sheets increases from 355 to 466 МPа and the relative elongation decreases insignificantly from 4 to 3.5%. The maximum strength with σ_0.2 = 410 МPа, σ_u = 460 МPа, and δ = 6.5% is provided by annealing at 150°C for 1 h of the sheets obtained via the technology with the maximum fraction of cold deformation (e_cold = 2.64). After annealing at 300°C for 30 min, a twofold increase in the plasticity is observed without a significant reduction in the strength characteristics a follows: σ_0.2 = 385 МPа, σ_u = 436 МPа and δ = 13%. It has been shown that the level of mechanical properties is determined by the substructure that is formed inside deformed grains during annealing.