Enhanced deep drawing formability and deformation mechanism of aluminum alloy at cryogenic temperature

In this paper, a novel deep drawing forming technique, which involved cooling dangerous areas with high plastic deformation using liquid nitrogen, was introduced to enhance the formability of complex-shaped aluminum alloy components. Uniaxial tensile tests were conducted on Al-Cu series alloys at different temperatures, demonstrating that decreasing the temperature from room temperature (RT) to cryogenic temperature (CT) increased the uniform elongation by over 50%. A deep drawing numerical simulation model was established for a complexshaped component used in aircraft body opening frame, and a set of forming molds that can control the cooling areas was designed based on the strain distribution. The results of the forming experiment showed that the new deep drawing technique successfully fabricated the component without cracks, whereas the conventional cold forming technique resulted in large-scale cracks at the bottom of the component. The mechanism behind the enhanced ductility of aluminum alloys was analyzed using dislocation slip, grain deformation, serrated flow, and fracture observations.