Enhancing creep formability and mechanical properties of creep-aged AA2050 alloys via slow heating

Abstract

In this work, a new creep aging route (pre-deformation+slow-heated creep aging, PSHCA) of AA2050 alloys was developed by the slow heating (20 °C/h) from 120 °C to 180 °C. The PSHCA alloy exhibits high creep strain with a simultaneous increase of strength and plasticity. The yield strength, ultimate tensile strength, and elongation reached 544 MPa, 581 MPa, and 11.1%, respectively. Both the rolling pre-deformation before aging and stress field during aging promoted the increased dislocation density and dense precipitation of T1 phases in the aged alloys, hence, the strength was improved at the expense of plasticity. Meanwhile, the bimodal diameter distribution of T1 phase of the PSHCA alloy and the enrichment of Ag atoms at T1/matrix interface was promoted by slow heating, slowing down the thickening of T1 phases. This further promoted the plasticity of PSHCA alloys while maintaining high strength. Additionally, the slow precipitation of T1 phase at the early stage of aging promoted dislocation slip and thus improving the creep strain of PSHCA alloys. These findings pave a way in designing large-curved and high-performance Al-Li components by creep aging technology.