Microstructural and Mechanical Characterization of Shear Formed Aluminum Alloys for Airframe and Space Applications

Advanced manufacturing processes such as near-net-shape forming can reduce production costs and increase the reliability of launch vehicle and airframe structural components through the reduction of material scrap and part count and the minimization of joints. The current research is an investigation of the processing-microstructure-property relationship for shear formed cylinders of the Al-Cu-Li-Mg-Ag alloy 2195 for space applications and the Al-Cu-Mg-Ag alloy C415 for airframe applications. Cylinders which have undergone various amounts of shear-forming strain have been studied to assess the microstructure and mechanical properties developed during and after shear forming. Introduction Near-net-shape manufacturing technologies represent attractive alternatives to traditional machining methods for airframe and launch vehicle structures [1]. The advantages of near-net-shape manufacturing include a reduction in the amount of material scrap in the form of machining chips and the elimination of thick-plate microstructures, which results in improved mechanical properties. Shear forming, also known as roll forming, is a near-net-shape manufacturing technique in which seamless cylindrical structures are produced by reducing the wall thickness and extending the length of ring-shaped preforms [2-3]. Shear forming was originally developed for steel; the shear forming of aluminum is in the early stages of development. The two methods of shear forming discussed herein are the counter-roller method and the mandrel method which are illustrated in Figure 1 [3]. The materials used in this study were processed and shear formed by Ladish Co. of Cudahy, Wisconsin. The results for the two alloys discussed here are not meant to be directly compared, since each represents a different stage in the development of the aluminum shear forming process.