Influence of particle content on the perforation resistance of structural aluminium alloys

In this study, we investigate the influence of constituent particle content on the ballistic perforation resistance of the two structural aluminium alloys 6063 and 6110. Each alloy was produced in two variants: one commercial type and one tailor-made type with about three times higher content of iron-rich constituent particles. The tailor-made alloys were intended to mimic the increased particle content that emerges from the impurity accumulation during multiple recycling cycles of the commercial alloys. Ballistic impact tests were then carried out by firing 7.62 mm AP bullets against 10 mm thick disks of the four different alloys, and the ballistic limit curves of the materials were determined. Further, a standard thermo-viscoplastic constitutive relation and an uncoupled ductile fracture criterion were calibrated based on quasi-static and dynamic material tests, and finite element simulations of the ballistic impact tests were conducted. The agreement between the numerical model and the experimental results was generally very good. The primary finding of this study is that the commercial and tailor-made alloys exhibit similar ballistic limit curves. This indicates that an increased content of constituent particles does not significantly affect perforation resistance. Thus, the results suggest that impurities accumulated during recycling have a limited impact on the protection level, provided that the strength and hardening capacity are not substantially altered. These findings have important implications for the development of sustainable protective structures.