Static and Dynamic Mechanical Properties and Ballistic Behavior of 6061 Aluminum Alloy

Aluminum alloys are widely used in aerospace, shipbuilding and high-tech fields due to their excellent mechanical properties. However, they often suffer dynamic impact loading during service. Study of their mechanical responses under dynamic loading conditions holds both theoretical and engineering significance. In this study, 6061 aluminum alloy serves as the research object. In-depth research is conducted through systematic experimental tests and numerical simulations to characterise the static and dynamic mechanical properties and the ballistic response of the alloy. The experimental results show that within the strain rate range of 0.001−3800 s−1, 6061 aluminum alloy exhibits significant strain-rate strengthening effect. The flow stress increases by 18.5% with the increasing strain rate. However, its strain hardening behavior remains relatively stable under different strain rate conditions. Parameters of the Johnson-Cook constitutive model calibrated by the least square method can accurately describe the mechanical response at different strain rates. The ballistic experiment results show that the ballistic limit of a spherical projectile penetrating 6061 aluminum alloy target plate is 283 m/s, and the residual velocity has a good linear relationship with the incident velocity under the super-ballistic limit condition. The failure morphology analysis of the target plate reveals that the failure mode is related to the impact velocity. At low impact velocities, the overall deformation is dominated by composite stress. However, at high penetration velocities, it is mainly local shear failure. The finite element model established successfully reproduces the ballistic response and failure mode observed in the experiments, with an error of less than 5%, verifying the reliability of the fitted constitutive model parameters and numerical methods. Using an experimentally verified finite element model, the ballistic responses of spherical projectiles with different diameters penetrating a 6061 aluminum alloy target plate are studied. When the projectile diameters are 10, 8, and 6 mm, the ballistic limit velocities of the target plate were 283, 392, and 443 m/s, respectively. Therefore, under the condition of unchanged thickness of the target plate, the higher the projectile mass, the greater the ballistic limit velocity of the target plate. This study provides important theoretical basis and experimental data, and thus supports the engineering application of 6061 aluminum alloy under impact load conditions.