Friction stir weld processing for achieving maximum tube-to-tubesheet leak path

The drawback of tungsten inert gas welded tube-to-tubesheet joints is shortened leak path between transfer fluids. In this work, solid-state friction stir welding is performed for investigating the combined effects of tube protrusions and radial clearances on tube-to-tubesheet joints made of AA 6061-T6 tube and AA 6063-T6 tubesheet. Joints with complete fusion over the entire clearance resulting in maximum leak paths are produced by the friction stir welding process. The average leak path of friction stir welded joints with 4.48 mm was higher than the 2.90 mm leak path of tungsten inert gas welded joints. The optimal tube pull-out load of 10,073.37 N using friction stir welding with 2 mm protrusion and 0 mm radial clearance is close to the maximum tube pull-out load of 10,081.84 N obtained using the tungsten inert gas welding process. Friction stir welding with protrusion was proven as an effective technique for producing tube-to-tubesheet joints with maximum leak path.