Annealing temperature influence on forming limit curve and fracture toughness of aluminium/silver bilayer sheets

• Annealing at 300 °C yields the most significant improvement in elongation and formability of Ag/Al bilayer sheets, with the effect most pronounced in aluminum layers. • Increasing annealing temperature reduces ultimate tensile strength and fracture toughness, while enhancing ductility and deep-cavity fracture behavior. • The cold roll bonding process with 70% thickness reduction and subsequent annealing produces a 350 μm Ag/Al bilayer with tunable mechanical properties. • Fracture mechanism transitions from shear ductile with shallow dimples to ductile with deep cavities as annealing temperature rises, as confirmed by SEM fractography.