Microstructure Evolution in a 6082 Alloy under Pulsed Magnetic Field Melt Treatment

Abstract

The 6082 alloy is used to produce DC (direct-chilling) billets for subsequent forging or rolling processes. It is necessary to control the solidification structure in casting billets during the casting process. Based on the previous work, the energy of the magnetic field was found to reduce the formation work of the larger cluster in the melt, leading to the formation of larger clusters in the melt, facilitating nucleation and refining the solidification structure. Inspired by this, the pulsed magnetic field melt treatment was applied upon the launder of the casting platform to affect the morphology, size and distribution of α-Al dendrites in the 6082 alloy DC-casting billet with a diameter of 380 mm. The experiment result shows that after the pulsed magnetic field melt treatment, the morphology of α-Al grains in the billet changed from coarse dendritic to small globular and its size was reduced by 18.5–45.4% compared to the existing process. Meanwhile, the difference in morphology of α-Al between the billet centre and edge decreased at the same time. This work may provide a new method for the grain refinement of the 6082 alloy DC-casting billet.

Keywords

• 6082 alloy
• grain refinement
• pulsed magnetic field melt treatment
• DC-casting
• microstructural analysis