(109967)Investigation into the hot forming-quenching integrated process with cold dies for high strength aluminum alloy

摘要

The hot forming of high-strength Al alloy is an effective method to achieve the lightweight structural parts on the premise of ensuring safety. Two different hot forming routes were proposed, i.e. hot forming-quenching integrated process with cold dies + 120 °C/24 h (HFQ~R +120 °C/24 h) and HFQ~R + pre-ageing + simulated baking (HFQ~R+PA + SB) respectively. The results show that the U-shaped parts under both routes exhibited good formability without obvious surface oxidation, and the overall mechanical properties were evenly distributed. The values of UTS and YS under HFQ~R + PA + SB can reach 558 MPa and 480 MPa, which are comparable to those attained under HFQ~R +120 °C/24 h. The volume fraction of η' phase under HFQ~R + PA + SB was found to be lower than that under HFQ~R +120 °C/24 h, and the size of η was larger for the former. The quantitative assessment of strengthening contributions to YS revealed that precipitation strengthening was the major strengthening mechanism. In comparison with HFQ~R +120°C/24 h, both dislocation density and solid-solution strengthening effects were improved to some extent under HFQ~R + PA + SB. The results demonstrate the feasibility of the novel HFQ~R + PA + SB route for the mass production of high-strength AA7075 structural parts, due to its efficiency and good overall mechanical properties.