Effect of cryorolling and annealing on recovery, recrystallisation, grain growth and their influence on mechanical and corrosion behaviour of 6082 Al alloy

In the present study, recovery, recrystallisation, grain growth, mechanical, and corrosion resistance of 6082 Al alloy subjected to cryorolling (CR) and annealing (AN) treatment were investigated. CR was performed to produce ultrafine grained structure and subsequently, AN treatment was given to investigate its influence on recovery, recrystallisation, and grain growth. The recovery and recrystallisation occurs between 110 and 250 °C and 250-300 °C respectively, where as grain growth starts from 300 °C due to insoluble dispersions (AlMn & AlMnSi) and Mg2Si precipitates in the alloy as evident from Differential scanning calorimetry (DSC), Electron back scattered diffraction (EBSD), hardness and Transmission electron microscopy (TEM) results. CR 6082 Al alloy has showed increased hardness of 120 VHN and ultimate tensile strength of 353 MPa. Annealing of CR 6082 Al alloy at 150 °C exhibited maximum hardness, ultimate tensile strength (UTS) and ductility of 127 VHN, 362.5 MPa, and 11%, respectively. CR of the 6082 Al alloy has produced high density of dislocation and increase in grain boundary area, which enabled the formation of dense oxide film on surface, enhancing its corrosion resistance. CR samples annealed at 350 °C shows excellent corrosion resistance as compared to as deformed Al alloy.