Effect of heat treatments on microstructural and mechanical characteristics of dissimilar friction stir welded 2198/2024 aluminum alloys

The 3rd generation of aluminum–lithium (Al–Li) alloys provides a desirable combination high mechanical properties and low density compared to their traditional counterparts, exempt lithium. Therefore, providing reliable joint between new conventional aluminum is crucial for making hybrid structures. present study focuses on improving the dissimilar AA2198/AA2024 joints using different heat treatments before after welding. Tensile tests paired with digital image correlation (DIC) techniques micro-hardness maps were performed document macro-scale local behavior joints. As-welded demonstrated similar yield strength, 30% lower than that base metals in T3 T8 metallurgical states. failed at AA2198 side affected zone (HAZ), parallel thermo-mechanically (TMAZ), region experiencing intense strain concentration minimal hardness values. Post welding-heat (PWHT) was found successfully strengthen HAZ side, without abnormal grain growth nugget impairing AA2024 side. This improvement related re-precipitation dissolved T1 (Al2CuLi) ? (Al2Cu) during welding as characterized by differential scanning calorimetry (DSC) microscopy analyses. However, PWHT variants reduction total elongation ultimate tensile strength due localization retreating much more homogeneous distribution as-welded