Effects of Mg and Si contents on the microstructure and mechanical properties of AA6014 alloys in T4P and T6P temper

Abstract

The effect of Mg and Si contents on the microstructures and mechanical properties of AA6014 alloys in T4P and T6P temper was investigated. Three-dimensional atom probe, Transmission Electron Microscope, Scanning Electron Microscope with Electron Back-Scattered Diffraction and tensile testing were used to characterize the evolution of microstructures and mechanical properties. The results show that the number density of clusters in T4P temper and solute aggregates in T6P temper increased by raising Mg and Si contents. Yield strength and ultimate tensile strength increased while elongation decreased with increasing Mg and Si contents in both T4P and T6P tempers. The strength is dominated by the number density of clusters in T4P temper, together with GP zones and β" precipitates in T6P temper. The total elongation is dominated by uniform elongation, which is related to the work hardening exponent. For the same combined Mg and Si content, the Si-rich alloy has better elongation than Mg-rich alloy due to higher work hardening exponent.