Effect of Solution Treatment on Mechanical and Corrosion Behaviors of 6082-T6 Al Alloy

Abstract

The mechanical and corrosion behavior of Al alloy 6082-T6 subjected to solution heat treating condition at temperatures varying from 400 to 600 °C and soaking times of 3–24 h have been investigated. Solution heat treating at 550 °C for 24 h led to the dissolution of the Mg2Si and AlSi6Mg3Fe precipitates into the matrix, and the Al12(FeMn)3Si2 phase transformed into Al85(Fe0.28Mn0.72)14Si phase. The solution-treated alloy showed equiaxed grain morphology with an average grain size of 85.7 µm. Increasing the solution heat treating temperature beyond 550 °C caused a reduction in corrosion resistance of the alloy. The pitting potential increased due to the presence of the anodic phase Mg2Si (dissolved at 550 °C) in Al matrix and it decreased with the formation of cathodic phases such as AlSi6Mg3Fe and Al12(FeMn)3Si2 (dissolved at 550 °C/24 h) in the alloy. General corrosion resistance of the alloy increased with decreasing Mg2Si concentration in the Al matrix. The optimum solution heat treating condition of 550 °C for 24 h resulted in an improvement in hardness (63 VHN), ultimate tensile strength (UTS—208 MPa), and pitting potential (−675 mV) and uniform corrosion potential (−1.255 mV) of 6082 Al alloy.