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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]

Ti–C particulate reinforced Ti6Al4V metal matrix composites (Ti6Al4V + 10 wt-%TiC) have demonstrated a high strength-to-weight ratio as well as good high temperature properties. A poor fusion welding performance is commonly observed in these materials making solid-state diffusion bonding a potential process to produce complex structural components. This work aims to characterise the microstructure and the mechanical properties of Ti6Al4V + 10 wt-%TiC diffusion bonded joints. Microstructural evaluation has been performed using both optical and scanning electron microscopy. Mechanical characterisation consisted of room temperature microflat tensile tests for the different bonding conditions and microhardness along the joint. The best results were associated with a bonding temperature of 1000°C and pressure 5 MPa together with bonding times ranging from 35 to 60 min. [ABSTRACT FROM AUTHOR]