TWI

The electrically assisted friction stir welding (EAFSW) technique, in which an electric current is fed through the workpiece to soften the metal by means of ohmic heating, is described and some trial experimental results are reported. The initial EAFSW set-up involved modifying a "Monarch" vertical milling machine by installing a slip commutation ring on its spindle. Welding was undertaken using AC at currents up to 700 A, and the vertical applied force was calibrated approximately with a weighing scale. Welding tool materials were studied with attention focused on metal alloys with high melting temperature and relatively low resistivity (e.g. molybdenum, steels, tungsten, tantalum, "Densimet" (W-Co-Cr alloy)). Experiments were conducted on sheet specimens (thickness 3.2-6.4 mm) of AA 5083 aluminium alloys, 1018 mild steel and titanium (commercially pure Ti and Ti, 6%Al, 4%V). A manual prototype machine was fabricated to facilitate in situ FSW repairs of aluminium alloy ship structural components, and some EAFSW results for 5083 and 6061-T6 alloys are discussed.

9th International Symposium, 15-17 May 2012, Session 7A: Variants II, Paper 03