Effect of Multi-directional Forging on the Evolution of Microstructural and Mechanical Properties of Lightweight Al-Cu-Li Alloy AA2050

Abstract

Microstructural evolution and the mechanical properties of recently developed lightweight AA2050 Al-Cu-Li alloy have been presented. A processing route of multi-directional forging (MDF) at 170 °C followed by artificial aging at 150 °C was employed. Systematic EBSD analysis revealed significant grain refinement with grain size reducing from 74.3 ± 12 to 22.1 ± 2.8 µm after 12 passes of MDF. Transformation of deformation bands into subgrains with dynamic recrystallization has led to grain refinement. TEM results show the presence of large dislocation clusters and deformation bands in MDF processed samples with a large number of fine precipitates in peak aged MDF processed samples. XRD analysis shows variation in peak intensities and occurrence of peak shifts due to induced lattice strain upon MDF. A substantial increase in microhardness and strength was observed with a minor trade-off with ductility after 12th MDF pass. Further, enhancement in strengths and microhardness were observed in post-MDF aged samples. Experimental results show the combined effect of strain hardening, grain size reduction, and precipitate hardening which influence the material strength. A combination of MDF and artificial aging has shown great potential to enhance the strength and ductility of AA2050. © 2023, ASM International.