Evaluation the Diffusion Bonding Process of Hardox 400 Steel and Aluminum Alloy AA7020 with Interlayer

Bonding of aluminum alloys and steel is of immense interest to different applications. In this study, we aim to determine the optimal conditions for diffusion bonding of Hardox 400 steel with Aluminum Alloy AA7020 using tin as the interlayer. Three loads: 150, 250 and 350 N, four temperatures: 400, 450, 500 and 550°C, and three times: 2, 4 and 6 hr were used. The optimal case for these conditions was evaluated using the double shear test, where it appeared that temperature and applied load have an important role in determining the shear stress, while time has a minor effect. The temperature of 550°C and the load of 350 N gave the best results at a time of 4 hr. To investigate the effect of the type of interlayer, steel and copper were used for this purpose under the optimal welding conditions, and the results revealed that the shear stress was low for both of them compared to tin, which appeared to be the best. To evaluate the effect of temperature at the constant load of 350 N and time 4 hr using tin as interlayer, microscopic examination, micro-hardness test and wear test were adopted. The results show that the increasing of process temperature led to improve the mechanical properties of joint and corrosion resistance due to more diffusion of atoms and Interfacial Transition Zone (ITZ) layer would be more thickened.