Effect of grain orientation angles and compressive parameters on the deformation characteristics and corrosion property of 6061 Al alloy

Abstract

The influence of grain orientation angle and processing parameters on the compressive flow stress and corrosion behaviour of 6061-T6 Al alloy was investigated in this study by altering the grain orientation angles in relation to the compressive direction. At relatively low processing temperatures (≤ 300 °C), an increase in the grain orientation angle from 0° to 90°reduced flow stress at low strain ranges (< 0.1) due to the facilitated slip of Al grains. As strain and processing temperature increased, changes in orientation angles had a negligible effect on the flow stress, attributed to the enhanced contribution of intermetallic particles (IMPs) and the occurrence of recrystallisation. Microstructural analysis revealed that higher processing temperatures resulted in a diverse range of IMPs, including Mg2Si (β phase) and Al15(Fe,Mn)3Si2 phases. When the Al alloy was compressed at a high strain rate (25 s−1) and processed at 500 °C, submicron-scale β”, β’, and β phases coexisted. Corrosion tests indicated that a wider distribution of Al15(Fe,Mn)3Si2 phases reduced the corrosion resistance of the Al alloy. This led to the formation of connected corrosion sites in specimens compressed at 500 °C, where a larger corrosion area and enhanced charge transfer ability were confirmed by equivalent circuit fitting. However, no significant variation in corrosion resistance was observed for Al alloys with various grain orientation angles, due to similar grain structure and precipitation behaviour at similar processing temperatures.