Superplastic forming of aluminum alloy tailored blank sheet joined by electron beam welding

摘要

Bulging is a typical type of deformation for superplastic blow forming of sheet metal, and it often causes undesirable thickness reduction in the formed part. Therefore, the control of thickness distribution in the formed part is strongly desired for making aerospace structures. A new technology called "Tailored Blank" was proposed to control the thickness distribution, and some forming experiments were conducted. Two kinds of tailored blank sheets were assembled from 1.0 mm-thick 5083 aluminum alloy as the base metal, using electron beam welding. One base sheet was joined with the same alloy of 1.6 mm thickness, and the other was joined with 5052 aluminum alloy of 1.0mm thickness. Pressurization schedules were analyzed considering suitable forming condition of the tailored blank (maximum strain rate of 5 × 10{sup}(-4)sec{sup}(-1) at 788 K) for the forming of a slender and rectangular pan. As a result, forming trials of these sheets were completed successfully, and these weld lines maintained their microstructure without harmful defects or local necking. This result shows a potential in the application of tailored blank technology with different thicknesses and different materials to superplastic forming.