Optimization of localized annealing for preform anneal forming of aluminum alloys

Preform anneal forming was developed to improve the formability of work hardenable aluminum alloys by introducing an annealing operation after the first forming stage (preform) (Krajewski, 2007). Annealing helps to eliminate the cold work from stage 1 forming and enable an aluminum panel to be formed into a complex shape in stage 2 forming using the same die. The main challenge for perform annealing is the added cycle time associated with a furnace annealing step. This challenge can be overcome if local heating can bo performed using induction heating or a similar technology. This paper presents a methodology to determine the optimal location of the annealed areas by combining finite element modeling and optimization methods. Simulation-based results on a typical 2D channel stamping and a 3D Marciniak cup drawing show, not surprisingly, that annealing the highest deformed zone is the best way to achieve larger stamping depths.