Dynamic impact behavior of 6061-T6 and 5083-H131 aluminum alloys

The results of a comparative study on microstructural evolution and damage in 6061-T6 and 5083-H131 aluminum alloys tested at high strain rates are discussed. Cylindrical samples of these alloys were tested in compression using instrumented direct impact Hopkinson Bar. Retention of heat and intense thermal softening along narrow bands during impact resulted in inhomogeneous deformation caused by shear strain localization along these bands. Deformed bands consisting of highly distorted and elongated grains were observed in the Aluminum 5083-H131 alloy after high velocity impact. On the other hand, adiabatic shear bands that look similar to the white etching bands commonly found in hardened steels were observed in the Aluminum 6061-T6 alloy. Whereas grain coarsening occurred inside the adiabatic shear bands in the Aluminum 5083-H131 alloy, the adiabatic shear bands in Aluminum 6061-T6 alloy were observed to contain much finer grains than the bulk material.