Effect of friction stir welding on dynamic properties of AA2024-T3 and AA7075-T7351

A split Hopkinson pressure bar or Kolsky bar system was used to determine the dynamic compressive flow behavior of two materials. Dynamic, compressive stress-strain curves were obtained of AA2024-T3 and AA7075-T7351 aluminum alloys and their welds as produced by the friction stir welding process. To show the strain rate effect, quasistatic tests, of these materials were also performed using a specimen configuration identical to that used in the dynamic tests. The experimental results showed 1) friction stir welding reduces the yield stress of the weld metal to below that of the base metal; 2) both materials exhibit the strain rate effect, i.e., the yield stress is higher under higher strain rates; and 3) the strain hardening appears to be similar for various strain rates.