A Weldability Study of Al–Cu–Li 2198 Alloy

Abstract

Al-Cu-Li alloys, conceived for automotive and aeronautic applications thanks to the high mechanical resistance/density ratio, exhibit weldability issues common to all light alloys. In this paper, the weldability of Al-Cu-Li 2198 alloy was studied by comparing features of welds carried out by two processes, the traditional arc welding and the friction stir welding (FSW). Welded joints were submitted to optical and SEM metallographic examinations with EDS microanalysis measurements. Mechanical characteristics were evaluated through microhardness tests and the instrumented indentation test FIMEC (Flat-top cylinder Indenter for MEchanical Characterization).

Microstructure distribution in an AA2050 T34 friction stir weld and its evolution during post-welding heat treatment

“…This absence of welding-induced coarse precipitation provides a very good homogeneity of mechanical properties in the T3W state, which has been observed before but not explained [33]. The subtle differences in cluster radius and volume fraction observed in the different zones of the weld are probably due to complex differences in vacancy concentration at the end of welding due to sweeping by dislocations and high temperature excursion.…”

“…Indeed, a large variety of precipitates can be observed in these alloys [13][14][15][16][17], from the Al-Li binary system (d 0 phase), from the binary Al-Cu system (GP zones, h 00 and h 0 phases), form the Al-Cu-Mg system for Mg-containing alloys (GPB zones, S 0 /S phases) and other phases from the Al-Cu-Li system (T 2 , T B ). Joining Al-Cu-Li alloys by friction stir welding has received some attention, both from the viewpoint of the resulting microstructure [18][19][20][21][22][23][24][25][26][27][28], mechanical properties [29][30][31][32][33] and corrosion behavior [34][35][36]. Most welded in the T8 temper, whose precipitate microstructure mainly consists of very thin platelets of T 1 particles and some h 0 as well as GP zones [9].…”

“…Intermediate zones (TMAZ, HAZ) consist of partially dissolved, coarsened T 1 precipitates, whose distribution have been mapped in the weld cross-section by spatially-resolved small-angle X-ray scattering (SAXS) [23,26]. Very little work has been devoted so far to Al-Cu-Li welds performed in the T3 state, although they show a very homogeneous hardness distribution [33]. Post-welding heat treatment has been shown to provide some interesting potential after welding in this condition although until now it has not been possible to avoid some remaining heterogeneity within the welded material [27].…”

Experimental Review on Friction Stir Welding of Aluminium Alloys with Nanoparticles

“…These alloys exceed the requirements of current and foreseeable future demands [19]. For instance, the Al alloy Al-Cu-Li has been used in aeronautic applications, such as in aircraft wings, for its density ratio to mechanical resistance [20]. Although Al alloys have desirable characteristics, reduction in material usage of fabricated structures also requires welding of complex joints and joining of similar and dissimilar Al alloys.…”

Effects of processing parameters on the microstructure and mechanical properties of Al–Si–Cu alloy after vacuum suction casting

“…Owing to their good ductility, processability, toughness and moderate strength, Al-Si-Cu multiphase alloys have been widely used in manufacturing complex thin-walled parts, such as automobile engine cylinder blocks, aeronautical compressor impeller blades and other aircraft parts. [1][2][3][4] At present, thin-walled parts are mainly processed using numerically controlled machining and gypsum die-casting, pressure casting, and anti-gravity vacuum suction casting. 5,6 Yanqing and others proposed bottom-hole VSC, based on anti-gravity VSC.…”