EUROPEAN CONGRESS AND EXHIBITION ON ADVANCED MATERIALS AND PROCESSES - EUROMAT 2021

The newly developed 2198 Al-Cu-Li alloy is a promising material for the aeronautical industry. Li addition reduces density, increases strength and Young's modulus making the material attractive to several applications. The current work contributes to the understanding of the mechanism of hot cracking phenomena which develop during laser beam welding (LBW) of the alloy. A study of the dendrite morphology adjacent to the crack path was performed using optical microscopy to reveal the microstructure of the specimens that had undergone LBW with different conditions. Then, Field Emission Scanning Electron Microscopy (FESEM) equipped with EDX analysis was used to reveal the chemical concentration profiles of the weld metal. To detect Li and to get further information about the redistribution of the chemical elements in the weld metal, X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES) were employed. The segregation of Cu that occurs during solidification was simulated using the Brody and Flemings model to obtain quantitative predictions of micro-segregation. The experimental and simulation results were also used to study the hot cracking susceptibility index proposed by Sindo Kou. The results indicated severe segregation of Cu within the interdendritic region, the cracked grains tend to be enriched in Cu on their interior in comparison with the non-cracked, and Cu-enriched grains are more likely to be found next to a crack.