Investigation of stress corrosion cracking of friction stir welded 2060 Al-Li alloy

Abstract Aluminum lithium 2060 alloy is an ideal structural material for aeronautical components. Friction stir welding (FSW) of two-millimeter-thick 2060 Al-Li alloy plates under a welding speed of 600 mm/min and rotation speed of 400 rpm flourishes as better joining process. During FSW process, the three zones of weld nugget zone (WNZ), thermally mechanical affected zone (TMAZ) heat affected zone and base metal (BM) on the weld transverse cross section are classified caused by tool stirring and axial force in friction stir welded joints. BM shows that the microstructure is characterized by lamellar structures of the lath-shaped α phase arranged along the rolling direction. The WNZ, with fine and equiaxed grains, is a typical feature of the recrystallized structures resulted from dynamic recrystallization due to severe plastic deformation and high temperature. The TMAZ, a transition zone surrounding the weld nugget experiences a combined action of friction heating and high bending. The equipment was designed and fabricated to investigate the stress corrosion cracking behavior in simulated environment. Electrochemical evolution of FSW Al-Li 2060 alloy in 3.5wt.% NaCl solution and performed open circuit potential, electrochemical impedance spectroscopy and cyclic polarization in unloaded condition and with applied load of 500, 1000 in specific intervals (1, 24, 48) hours. Results show that poor corrosion resistance in unloaded condition and decrease with the specific time interval. Results show that corrosion rate in unloaded 102, for 500 g load is 7.5 and for 1000g load is 48.76 in millimeter per year (mm/y).