Microstructure Evolution and Microstructural Characteristics of Al–Mg–Si Aluminum Alloys Fabricated by a Modified Strain-Induced Melting Activation Process

Abstract

Abstract:A modified strain-induced melting activation (SIMA) process is shown to improve high-temperature formability. The microstructural characteristics of the spheroidized grains of SIMA-processed alloys affect high-temperature formability. The effects of hot extrusion parameters and chemical composition on the evolution of spheroidized grains were investigated using several 6xxx series aluminum alloys subjected to a modified SIMA process. The results show that 6066 aluminum alloy is the most suitable alloy for the SIMA process, as it contains sufficient Mg, Si, Cu, and Mn. Adequate amounts of Mg, Si, and Cu lead to a high liquid fraction, and a sufficient addition of Mn inhibits grain growth. Proper hot extrusion parameters are essential, because initial fine and uniform recrystallized grains lead to fine and uniform globules. The phases at the global grain boundaries of 6066 aluminum alloy are eutectic phases of Al and Si, Al and Mg 2 Si, and Al and Al 2 Cu, as analyzed using transmission electron microscopy.

Mechanical properties and microstructure of aluminium alloy AW6082-T6 joints welded by double-sided MIG process before and after aging

“…It has been observed that Mg and Si increases the susceptibility of the alloy to hot cracking and that the concentration of Mg and Si is often higher near the cracks [4,7]. Studies also show that the structure of the extruded aluminium alloy 6082, aged in a salt bath at 620 o C, has a lower degree of recrystallization of grain growth and that Mg and Si concentrations are higher at the grain boundaries [8]. Furthermore, one of the most severe problems in welding aluminium alloys is the development of hydrogen gas porosity during solidification [9].…”