Optimization of 6016 Aluminum Alloy Selection for Outer Panels

Important design requirements for an outer autobody panel are stiffness and dent resistance performance which depend on panel geometry and mechanical properties of the sheet. Specific grades of PECHINEY 6016, named as DR for « dent resistance », were designed for enhanced strengthening during paint baking. An experimental program was carried out to relate panel thickness and strength to both stiffness and dent resistance in quasi-static and dynamic (10-15km/h) conditions. Tests were performed on non prestrained flat and curved 6016 panels of different thicknesses and paint bake strengths. Steel grades and thicknesses typical of outer panels were used for comparison. Local stiffness, independent of strength, was confirmed to increase with panel curvature and sheet thickness. Static and dynamic dent resistance, which increase with sheet thickness and strength, were found to depend on panel curvature. Empirical expressions relating these properties to strength and sheet thickness were derived. The 6016 DR130 variant improves dent resistance with respect to standard 6016.