Deformation behavior of Al-Cu-Mg alloy during non-isothermal creep age forming process

Creep age forming process (CAF) has been developed for manufacture large aircraft components. Generally, in CAF, the component should experience heating, soaking and cooling stages. In order to acquire high precision of the creep-age formed components, the non-isothermal deformation behavior of Al-Cu-Mg alloy was investigated using the creep ageing, thermal expansion, hot tensile and creep age forming tests. During non-isothermal creep ageing process, both the elastic and thermal deformations grow in the heating stage. However, the elastic deformation drops to a certain degree and then the contraction occurs in the cooling stage. The non-isothermal creep deformation can be divided into six stages, in which the creep rate increases in the heating stage and decreases in the soaking and cooling stages. Under different applied stresses, the creep strain in the heating stage of the non-isothermal creep is about 22.28-26.86% of the total creep strain. Compared with the isothermal creep ageing process, steady-state creep rate of the non-isothermal creep ageing process is reduced. Nevertheless, total creep deformation in the non-isothermal creep ageing process is improved. Thus, the springback of the non-isothermal creep-age formed plate is smaller than that of the isothermal creep-age formed plate. It can be concluded that the creep behavior in non-isothermal conditions, particularly the heating stage, needs to be considered in CAF applications.