TWI

The floating bobbin friction stir welding (FSW) technique was employed to develop high performance aluminium floor slabs for road bridges and experiments were undertaken to investigate the influence of heat input on fracture location. Butt joints were fabricated in 6061-T6 aluminium alloy plates (thickness 16.5 mm) using a floating bobbin FSW tool at tool rotational speeds of 250-400 rpm and welding speeds of 100-300 mm/min. Defects, macrostructures and microstructures in weldment transverse cross sections were observed by metallographic inspection. Mechanical properties were characterised by tensile, side bend and axial stress controlled fatigue tests. Fracture occurrence at large tunnel like voids, at the stir zone-parent metal boundary, at the HAZ and at the joint line remnant under, respectively, very high, high, appropriate and very low heat input conditions is discussed. A mass production technique for floor slabs is outlined.

11th International Symposium, 17-19 May 2016, Session 2A: Applications I, Paper 05