Effect of equal-channel angular pressing and aging on the microstructure and mechanical properties of an Al-Cu-Mg-Si alloy

Abstract

The effect of intermediate equal-channel angular pressing (ECAP) and final aging at 170°C on the mechanical properties and microstructure of aluminum alloy belonging to Al-Cu-Mg-Si system stress with a Cu/Mg ratio (AA2014) is considered. After quenching and aging (treatment T6), the yield stress (σ0.2) and ultimate tensile strength (σu) are ∼415 and ∼450 MPa, respectively; the elongation to fracture (δ) is 4.2%. The precipitation strengthening is reached due to the precipitation of θ″-, θ′-, β″-, and Q′/C-phase particles. After intermediate ECAP and subsequent aging for 0.5 h, σ0.2 and σu increase to 470 and 535 MPa, respectively; δ increases to ∼9.5%. The plastic deformation leads to the formation of a microstructure that consists of deformation bands characterized by a high density of dislocations. During aging for 0.5 h, the partial decomposition of supersaturated solid solution and formation of segregations within grains and at dislocations and precipitation of the Guinier-Preston zones and β″ phase also occur; all of this ensure the maximum increase in the strength of the AA2014 alloy. As the aging time increases to 8 h, the slight decrease in both σ0.2 and σu to 465 and 515 MPa and δ to ∼6% takes place. It has been shown that the intermediate ECAP does not affect the sequence of the precipitation of main strengthening θ″ and θ′ phases during aging. However, in this case, the volume fraction of strengthening particles decreases significantly and their dispersivity increases.