TWI

An investigation is presented into the fatigue characteristics of friction stir welded (FSW) lap joints made from artificially aged Al alloy 6082 (Al, 0.6-1.2%Mg, 0.7-1.3%Si) using a tool based on the "Triflute" concept with either convex or concave pin ends and tool shoulder diameter of 15 or 18 mm. FSW of sheet specimens of 4 mm thickness was conducted at a feed rate of 300 mm/min and a tool rotation speed of 1500 rpm. The static and dynamic strengths of the welds were determined in a servo-hydraulic testing machine. Fracture initiation and propagation were studied by tensile and fatigue testing, and macroscopic observations and Vickers hardness measurements were undertaken. The mechanisms responsible for the observed dependence of fatigue performance on pin end shape and tool shoulder diameter are discussed.

5th International Symposium, 14-16 Sep 2004, Session 6B: Mechanical Properties, Paper 02