Friction Stir Welding of Al-Li AA2199: Parameters, Precipitates and Post Weld Heat Treatment

Rosen Ivanov; Julien Boselli; Diana Denzer; Daniel Larouche; Raynald Gauvin; Mathieu Brochu

doi:10.4028/www.scientific.net/AMR.409.853

Paper Titles

Formation of Deformation-Induced Divorced Eutectoid Pearlite above the Ae₁
p.829

Thermomechanical Processing of a Nb-Microalloyed Steel in a Controlled-Forging Treatment
p.835

Solid Freeform Fabrication of Al-Li 2199 via Controlled-Short-Circuit-MIG Welding
p.843

Degradation Mechanism of Tungsten Electrode for Fusing Joining
p.849

Friction Stir Welding of Al-Li AA2199: Parameters, Precipitates and Post Weld Heat Treatment
p.853

Determination of Global and Local Tensile Behaviours of Laser Welded Ti-6Al-4V Alloy
p.859

Brazing of Cemented Carbides at Lower Temperatures
p.865

Studies on Shielded Active Gas Forge Welded API 5CT L80 Material at Different Cooling Rates
p.871

Assessment of Mechanical Parameters of PMMA Used in Human Body
p.877

HomeAdvanced Materials ResearchAdvanced Materials Research Vol. 409Friction Stir Welding of Al-Li AA2199: Parameters,...

Friction Stir Welding of Al-Li AA2199: Parameters, Precipitates and Post Weld Heat Treatment

Abstract:

The aerospace industry strives to develop materials allowing an increase in payload and reducing fuel consumption. Al-Li alloys, with their low density and high strength are currently in use for such applications and have potential for additional applications. When compared to composites, utilizing Al-Li alloy products is cost effective for aerospace companies as they do not need to redesign pre-existing fabrication facilities. The joining of these alloys by conventional methods is limited by segregation of alloying elements and the formation of oxides during high temperature exposure. This study focuses on solid state joining method that has the potential to generate low heat and be defect free - Friction Stir Welding (FSW). AA2199 sheets were joined by FSW. Process variables included table force, tool rotation speed and weld travel speed. A post weld heat treatment (PWHT) was applied to improve the mechanical properties by precipitation of strengthening phases. An increase in hardness of the weld zone from 95HV to 125HV upon PWHT was recorded for selected welding conditions. The type and morphology of second phase precipitates is deemed responsible for this effect. It is suggested that the high temperature and high strain levels characteristic of welds with fast tool rotation allow for the dissolution of precipitates during welding. The re-precipitation of these second phases during PWHT allowed the welds to recover strength to the level of the base material.