Effect of annealing on formability and mechanical properties of AA1050/Mg-AZ31B bilayer sheets fabricated by explosive welding method

In this article, for the first time, the effect of annealing was investigated experimentally on the formability and mechanical properties of AA1050/Mg-AZ31B bilayer sheets fabricated by the explosive welding method. To eliminate the work hardening due to the explosive welding and improve the formability of the bilayer sheet, annealing was carried out at 250 degrees C and 350 degrees C for 2 h. The Nakazima test explored the samples' formability to determine the corresponding forming limit diagram. The mechanical properties and microstructural features were assessed by tensile test, micro hardness, optical microscope, and scanning electron microscopy. Annealing at 250 degrees C showed no significant growth of the layer in the interface; but elevating the annealing temperature to 350 degrees C intensified the interface layer growth and increased its thickness from 7 for the initial sheet to 27 mu m which can be assigned to the activation of the diffusion mechanism. The influence of the interface thickness increase on the mechanical properties decreased the strength of the bilayer sheet. FLD0 showed a 52% and 22% increase upon annealing at 250 degrees C and 350 degrees C, respectively. The decrease in the formability after 250 degrees C can be due to the formation of brittle intermetallic compounds in the interface layer.