Abstract
Alloy sheets of type 2060 aluminum–lithium were welded by laser beam welding (LBW) filled with ER2319 Al-5.6Cu wire. Microstructural observations showed the uneven distribution of columnar grains, equiaxed grains and equiaxed dendrite grains in the weld. The θ′(Al2Cu) phase and other phases precipitated in the weld. The θ′(Al2Cu) phase centrally distributed at the grain boundaries. During the immersion corrosion, the pitting corrosion first occurred and then gradually expanded and transformed to intergranular corrosion and exfoliation corrosion. The electrochemical corrosion test showed a higher corrosion tendency of the base metal and heat-affected zone for the lower corrosion potential, but the corrosion current density of the weld was relatively larger. The segregation of Cu, Mg and other elements at the grain boundary aggravated the occurrence of intergranular corrosion.
Highlights
Aluminum–lithium alloys are finding more and more applications in the aviation industry as researchers aim to achieve weight reduction and strength improvement in skin materials
A disc with a diameter of 3 mm for transmission electron microscopy (TEM) observation was polished to 0.5 mm in thickness after wire-electrode cutting from the central area of the weld
Part of the moisture, which may havedistribution come from location the non-pre-heated wire and/or according to the analysis of Song et al [16], the precipitation of supersaturated H from the sheet surface and could not be removed by shielding gas, was adsorbed into the liquid metal liquid metal during the solidification of the molten pool will result in the formation of metallurgical during welding because the Al–Li alloy has high moisture absorption
Summary
Aluminum–lithium alloys are finding more and more applications in the aviation industry as researchers aim to achieve weight reduction and strength improvement in skin materials It is very important for the application of light aluminum alloys. Type 2060 aluminum–lithium alloy is a kind of the third generation Al–Cu–Li–Mg series alloy and it is strengthened by precipitations formed during aging treatment It is an ideal aero-material and has been widely used in the aviation industry [4]. Studied the influence of thermomechanical treatments on the localized corrosion susceptibility and propagation mechanisms of AA2099 Al–Li alloy They found that the severe localized corrosion of the alloy of T8 condition was associated with localized plastic deformation occurring during the pre-age cold working and heterogeneous precipitation of the T1 (Al2 CuLi) phase during subsequent artificial aging. The microstructure, micro segregation of alloying elements, the phase constitution, and corrosion resistance of the welded joints in 3.5 wt.% NaCl solution were investigated
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