TWI

To investigate the potential of mechanical tensioning (MT) to reduce residual stresses in friction stir welding (FSW), thereby eliminating buckling, FSW was performed on 2024-T351 aluminium alloy (thickness 3.2 mm) with different tensile stress levels applied along the weld line (during or after welding), and the resulting welds were characterised by out-of-plane distortion and residual stress profiles. The MT system employed hydraulic rams to apply a controllable/constant stress, with the sheet ends gripped by pin-loaded clamps. Residual stress measurements were undertaken using energy-dispersive x-ray diffraction. A relationship between optimum tensioning stress and FSW heat input was established. The MT technique was also studied for FSW on thicker material (AA-7449, thickness 12 mm).

6th International Symposium, 10-13 Oct 2006, Session 5B: Residual Stresses, Paper 04