Study On Deformation Behavior And Constitutive Relationship Of High Performance Aluminum Alloy During Creep Aging

Modern aerospace equipment tends to be lightweight,long life and high reliability,which puts forward higher requirements for the performance of aircraft structure.Creep aging forming technology is a kind of technology which combines component forming and aging strengthening.It is an important part of manufacturing high precision and high performance large integral panels in China's"large aircraft"project.The technology has been studied abroad and successfully applied in industrial production.Due to the late start and lack of research on forming mechanism in China,some progress has been made in creep aging forming technology of aluminum alloy,but no complete system has been formed,which restricts the development of aviation industry in China.Creep of materials The study of aging characteristics is one of the key basic scientific problems in creep aging forming technology.In this paper,the creep aging characteristics and deformation mechanism of AlMgSiCu alloy for aeronautical applications are studied,and the main factors affecting the creep behavior of AlMgSiCu alloy are analyzed,and the constitutive model based on macro and micro parameters is established.The main conclusions are as follows:(1)Compared with artificial aging,creep aging accelerates the aging process of the alloy and increases the peak hardness of the alloy to 139.74 HV.The tensile strength of the alloy after creep aging is obviously higher than that after artificial aging at the same aging temperature and different aging time.(2)Creep temperature and experimental stress are important factors affecting creep behavior of alloy.Creep strain and creep rate increase with the increase of creep temperature and stress level.(3)At 150?~170?,the tensile strength of the alloy increases with the increase of stress,and the external stress promotes the precipitation of the strengthened?''phase and the transformation to the stable equilibrium?phase.The tensile strength reached a peak of453.6 MPa at 150?,200 MPa.(4)The precipitation and growth of precipitate phase were promoted with the increase of aging temperature in the stress range of 150~200 MPa.When the temperature was 170?,some precipitated phases coarsened and grew,the alloy became overaged and the tensile strength decreased to 396.8 MPa.(5)The power law constitutive model,hyperbolic sinusoidal constitutive model and creep constitutive model based on grain size of AlMgSiCu alloy are established.By fitting and verifying,it is concluded that the hyperbolic sinusoidal constitutive model can better describe the creep behavior of AlMgSiCu alloy.The apparent creep stress exponent is 3.29,and the activation energy is Q_c=115.972 KJ/mol.According to the typical creep mechanism,dislocation slip is the main creep mechanism of AlMgSiCu alloy.