Microstructure and mechanical properties of Al-Mg-Si alloy during solution heat treatment and forging integrated forming process

Abstract

The integrated forming process of an Al-Mg-Si alloy was designed, which combined solution heat treatment (SHT) and hot forging into one operation followed by artificial aging. The effect of deformation strains on the microstructure and mechanical properties was investigated by electron backscatter diffraction (EBSD), X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), and tensile tests. The results show that the tensile strength and yield strength of the compressed specimens were increased by at least 12.9% and 13.8%, respectively, when compared to the undeformed T6 specimen. {001}〈110〉 and {011}〈110〉 texture components were produced at low strains and gradually vanished as strain increased, in contrasting to the T6 specimen, which produced strong recrystallized texture components. As a result of the dynamic recovery (DRV) mechanism, intense {112}〈110〉 and {111}〈110〉 texture components were obtained in the integrally processed specimens at high strains along with a high fraction of low angle grain boundaries (LAGBs). The dispersed Al12(Fe,Mn)3Si phases aided in the formation of cellular structures and facilitated in the development of the DRV. The dislocations significantly accelerated the precipitation of β'' phases, which conversely pined the movement of dislocations and improved the mechanical properties of the Al-Mg-Si alloy.