On the microstructure and mechanical properties of AW2099 aluminium lithium alloy joints produced with electron beam welding

摘要

The effect of electron beam welding process on the microstructural and mechanical characteristics of newly developed 3rd generation AW2099 heat treatable aluminium lithium (Al-Li) alloy was investigated. Non-dendritic equi-axed zone (EQZ) is formed at the heat affected zone (HAZ) - weld metal (WM) interface. This zone consists of fine equi-axed grains, while the eutectics based on alpha-aluminium + theta-Al2Cu are preferentially precipitated at the grain boundaries (GB). Increased content of iron, silicon and manganese was detected in some inter-dendrite sites. Furthermore, beta-AlLi and gamma-Al2Li3 compounds were recorded in the columnar dendritic zone (CDZ). Electron beam welding (EBW) resulted in dissolution of strengthening precipitates, thus the decrease in nano-indentation hardness in EQZ was observed in comparison to HAZ. (C) 2020 Elsevier B.V. All rights reserved.