Abstract
High strain-rate compressive stress–strain characteristics of AA7075-T651 and its welds as produced by the friction stir welding (or FSW) process are investigated using the conventional split Hopkinson pressure bar. Friction stir welded AA7075-T651 joints are made under a fixed set of welding conditions. Cylindrical specimens machined along the thickness direction of both the base material and the friction stir weld nugget region are used in the static and impact compression tests. The micro-hardness tests are conducted across the centerline of the friction stir welded AA7075-T651 joint in order to examine the microstructural change. It is shown that the compressive flow stress of the weld nugget is reduced to about 70 to 85% of that of the base material, and that both the base material and the weld nugget exhibit almost no strain rate effect up to nearly ε˙=103/s.
