Residual Stress Field in a Friction Stir Welded Aluminium Extrusion

摘要: Friction stir welding (FSW) is a relatively new technique, which makes it possible to weld low fusion weldability materials with very little or no post distortion, high mechanical strength and good fatigue performance. This particularly important for precipitation strengthened aluminium alloys of the 7xxx series previously not recommended welding. Residual stress measurements have been made, using synchrotron X-ray diffraction transmission on alloy plate made by friction butt two extruded T-profiles along their middle section. Measurements were also carried out non-welded section determine pre-welded strain state. Comparisons holographic interferometry method. Hot extrusion thin walled sections results in substantial preferred orientation. The grains appear mainly equiaxed transverse highly elongated longitudinal directions, described as fibre texture. During welding, original texture destroyed. In stirred region, fine grained recovered microstructure observed, whereas thermo-mechanically affected zones, intermediate. strongly textured difficult accurately residual fields traditional measurement techniques but non-destructive scanning produced excellent over full cross-section weld.