Effect of deformation degree on the creep age forming of 7475 aluminum alloy: The feasibility of the extended deformation range

Abstract

The deformation degree of many integrated stiffened panels expected to adopt the creep age forming process, exceeds the linear elastic range. However, there is no research report on the possible results therefrom. And it is significant for the structural design and process optimization to systematically study the effect of deformation degree on the property and microstructure of the creep aging formed parts and ascertain the suitable deformation range. For this purpose, a series of creep age forming experiments of AA7475 sheet specimens with different curvature radiuses were conducted employing a radius-adjustable forming tool. Results indicated that the strength property varies by a low-to-peak-to-low manner as the increase of the deformation degree, and the radius-thickness ratio of the peak strength maintains a constant. Moreover, the measured range of the property fluctuation amplitude is 3.5–5.8%, which means a certain property difference may exist on different local regions of an integrated component with various curvature radiuses. In order to reduce the possible negative effect, it shall be necessary to pre-consider this factor and design a reasonable deformation range before the practical manufacturing process.