Influence Of Cold Deformation And Aging On Microstructure And Properties Of Aluminum Alloy2219

In this work, we used pre-stretch and cold-rolling to study the influence of colddeformation and aging on microstructure and properties of aluminum alloy2219. Opticalmicroscopy and transmission electron microscopy were used to study the grain changesand the type, morphology, size and distribution of precipitation respectively. DSC as amethod to research the law of thermodynamics of second phase precipitation. Roomtemperature tensile test was used to characterization mechanical properties of differentheat treatments to get hardening law during the process of cold deformation.The microstructures and properties of2219aluminium alloy were studied underaging treatment in different temperatures. The results of this part experiments wereobtained. The highest peak ageing strength can be achieved at170°C and then at190°C,150°C,210°C from high to low. So170°C/12h aging process should be chosen as theperfect ageing treatment. The yield strength, tensile strength and elongation of thisprocess were319.2MPa,440.5MPa and14.2%respecttively.The influence of cold deformation on this alloy were studied by stretching and cold-rolling process. The results of this part experiments were obtained. Large deformation ofcold-rolling leads to grain breaking and the new little grains are perpendicular to therolling direction. Cold deformation can decrease the precipitate temperature of θ′phase,while the precipitate temperature decreases more slowly with the increase of thedeformation. Both increasing temperature and enhancing deformation can accelerate theprecipitate of θ′phase, especially the temperature. Enhancing the deformation of thisalloy at170°C can stimulate the nucleation of θ′more obviously than150°C。The influence of cold deformation on microstructure and mechanical properties wasstudied by aging treatment. The results are obtained as below. AA2219is suggested toselect170°C/2~4h aging treatment after small deformation (<20%), because at thissituation most deformation strengthening can be preserved in alloy and theθ′play a roleof second phase strengthening. Pre-stretch10%/170C/4h and cold-rolling20%/170°C/2hwere two kinds of typical processes. The yield strength, tensile strength and elongationof the above two processes were376.8MPa,463.3MPa,10.7%and365.6MPa、431.7MPa 和6.3%, respectively. AA2219is suggested to select150°C and prolonged agingtreatment after large deformation (>50%). Most deformation strengthening can bepreserved as well and the θ″play the role of second phase strengthening. In addition, theelongation increased with the increase of aging time. Cold-rolling80%/170°C/4h is atypical process and its yield strength, tensile strength and elongation were420.0MPa,483.1MPa and12.1%.