Al-Li alloys are attractive for military and aerospace applications because their properties are superior to those of conventional Al alloys. Their exceptional properties are attributed to the addition of Li into the Al matrix, and the technical reasons for adding Li to the Al matrix are presented. The developmental history and applications of Al-Li alloys over the last few years are reviewed. The main issue of Al-Li alloys is anisotropic behavior, and the main reasons for the anisotropic tensile properties and practical methods to reduce it are also introduced. Additionally, the strengthening mechanisms and deformation behavior of Al-Li alloys are surveyed with reference to the composition, processing, and microstructure interactions. Additionally, the methods for improving the formability, strength, and fracture toughness of Al-Li alloys are investigated. These practical methods have significantly reduced the anisotropic tensile properties and improved the formability, strength, and fracture toughness of Al-Li alloys. However, additional endeavours are required to further enhance the crystallographic texture, control the anisotropic behavior, and improve the formability and damage tolerance of Al-Li alloys.
Lightweight sheet metals are attractive for aerospace and automotive applications due to their exceptional properties, such as low density and high strength. Sheet metal forming (SMF) is a key technology to manufacturing lightweight thin-walled complex-shaped components. With the development of SMF, numerical simulation and theoretical modelling are promoted to enhance the performance of new SMF technologies. Thus, it is extraordinarily valuable to present a comprehensive review of historical development in SMF followed by state-of-the-art advanced characterization and modelling approaches for lightweight metallic materials. First, the importance of lightweight materials and their relationship with SMF followed by the historical development of SMF are reviewed. Then, the progress of advanced finite element technologies for simulating metal forming with lightweight alloys is covered. The constitutive modelling of lightweight alloys with an explanation of state-of-the-art advanced characterization to identify the constitutive parameters are presented. Then, the formability of sheet metals with major influencing factors, the techniques for measuring surface strains in SMF and the experimental and modelling approaches for determining the formability limits are clarified. Finally, the review is concluded by affording discussion of the present and future trends which may be used in SMF for lightweight metallic materials.
Since AA2060-T8 was introduced in the past few years, investigating the mechanical response, fracture mechanisms, and anisotropic behaviour of AA2060-T8 sheets under high strain rate deformation has been crucial. Thus, uniaxial tensile tests were performed under quasi-static, intermediate, and high strain rate conditions using universal testing machines as well as split Hopkinson tensile bars. The experimental results showed that the ductility of AA2060-T8 sheets was improved during high strain rate deformation because of the adiabatic softening and the inertia effect which contribute to slow down the necking development, and these results were verified by the fracture morphologies of high strain rate tensile samples. Furthermore, the strain rate hardening influence of AA2060-T8 was significant. Therefore, the Johnson-Cook constitutive model was modified to consider the effects of both strain and strain rates on the strain hardening coefficient. The results obtained from the improved Johnson-Cook constitutive model are in remarkable accordance with those obtained from experimental work. Thus, the improved Johnson-Cook model can predict the flow behavior of AA2060-T8 sheets at room temperature over a wide range of strain rates. The results of the present study can efficiently be used to develop a new manufacturing route based on impact hydroforming technology (IHF) to manufacture sound thin-walled-complex shape components from AA2060-T8 sheets at room temperature.
1 October 2018 in International Journal of Machine Tools and Manufacture