TWI

The influence of the tool profile and short welding cycles on the friction stir spot welding (FSSW) of thin aluminium sheet was investigated using several different techniques including high-resolution x-ray tomography. Weld quality, microstructure, interface position during welding and lap shear strength were studied. Spot welds were produced in 6111-T4 AlMgSi alloy (0.93 mm thickness) with no surface cleaning or surface preparation before welding, using four different pinless tools made from H13 tool steel. Rotational speed was 2000 rpm, plunge depth 0.2 mm and dwell time varied from 0-2.5 s. Material flow and defect distribution were examined by FSSW aluminium alloys with dissimilar copper content (6082 and 6011). The ways in which the tool shoulder affects metal flow were determined. Mechanisms of weld formation using a pinless tool are discussed.

8th International Symposium, 18-20 May 2010, Session 7A: Automotive Spot 1, Paper 01