Microstructural and mechanical investigation of aluminum tailor-welded blanks

The push to manufacture lighter-weight vehicles has forced the auto industry to look to alternative materials than steel for vehicle body structures. Aluminum is one such material that can greatly decrease the weight of vehicle body structures and is also consistent with existing manufacturing processes. As in steel structures, cost and weight can be saved in aluminum structures with the use of tailored blanks. These blanks consist of two or more sheets of dissimilar thicknesses and/or properties joined together through some type of welding process. This enables the design engineer to tailor the blank to meet the exact needs of a specific part. Cost savings can be gained by the elimination of reinforcement parts and the stamping dies used to manufacture them, Weight savings can be attained based on the fact that one thicker piece is more efficient than a welded structure and therefore can allow for down-gauging of parts. Although tailor-welded blanks (twbs) offer both potential weight and cost benefits, the continuous weld-line and thickness differential in twbs can often result in difficulty in stamping. This problem is more severe in aluminum because of its limited formability as compared with typical drawing-quality steels. Additionally, welding of steel twbs tends to increase the strength of the weld material, which helps prevent failure in the weld during forming. Aluminum twbs do not experience this increase in strength and therefore may have a greater tendency to fail in the weld. In this study, several aspects of twbs manufactured from 6111-T4, 5754-O, and 5182-O aluminum alloys were analyzed and compared with those of a more conventional steel twb, The effect of gauge mismatch on the formability of these blanks is discussed as well as the overall potential of these blanks for automotive applications.