Immersed Friction Stir Welding

Immersed Friction Stir Welding (IFSW) involves producing friction stir welds completely submerged in a liquid, usually water. Immersed friction stir butt welds were run on AA6061-T6 for comparison with conventional FSWs made using the same tooling and parameter windows. The welds were made at rotation speeds of 1000 – 2000 rpm and travel speeds ranging from 5 – 14 in min^-1. A prior study of immersed friction stir processing (FSP) has shown that much finer grains may be produced in the weld nugget with IFSW. Although previous work has been published in submerged friction stir processing, SFSP, no data was presented regarding improved yield strength in FSW. The reduction in grain size is expected to produce
comparable or greater yield strengths relative to conventional FSW. Tensile tests
were conducted on both sets of welds. Welds were subsequently cross sectioned and
hardness testing was conducted as well to verify prior publications. Temperature
of the welds was recorded with the use of thermocouple implantation. Properties of
these welds vs. traditional welds and other welding methods are investigated with
respect to on-site underwater repair and/or construction to determine the future
viability of this joining technique in industry.