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Tailor welded blanks (TWBs) are produced by joining at least two sheets of dissimilar gauge and/or properties to achieve a lighter blank of desired stiffness and strength. In this way, the properties of the blank may be tailored to meet the design requirements of a panel. As in steel structures, cost and weight can be saved when using the TWB concept for aluminium. However, use of aluminium is a concern in the automotive industry because of well documented weldability and reproducibility problems, since relatively minor changes in welding parameters may affect the quality of the weld. Friction stir welding offers an attractive alternative to conventional fusion welding methods because of the excellent properties (particularly ductility), reproducibility, robustness and surface finish obtained. However, the working envelope for friction stir welded tailored blanks has yet to be fully explored. In the present study TWBs of the alloy 6181-T4 in a thickness combination 1 to 2 mm have been produced. The influence of welding parameters and welding tools on the weld quality and mechanical properties has been determined. Satisfactory surface finish with no detrimental effects to the mechanical properties has been observed. Weld efficiencies >90% have been consistently achieved. [ABSTRACT FROM AUTHOR]

Dissimilar weldments comprising age hardenable AA7075 and AA6056 aluminium alloys were produced by friction stir welding. Corrosion behaviour of the weld nugget/thermomechanically affected zone and parent materials was characterised in chloride solutions. Chromate, molybdate and cerium nitrate were added to the chloride solution and their effect on the corrosion behaviour of the weldment was assessed. Electrochemical studies on different regions of the dissimilar friction stir weldment, performed in inhibited 3·5%NaCl solutions, suggest that chromates are better in terms of inhibition efficiency and inhibit all regions of the weld area to a similar extent. From the viewpoint of environmental issues, both molybdate and cerate may also be thought of as effective inhibitors; however, their efficiencies are definitely below that of chromates in neutral chloride environments. [ABSTRACT FROM AUTHOR]