Pre and post rolling homogenization of direct chill cast Al-6Mg alloy: effect on microstructure and mechanical properties

ABSTRACT

Production of high-Mg content Al–Mg alloys in the form of sheet from cast condition, should be performed with some pre- and post-deforming treatments to achieve desirable mechanical properties. In this research, to find the necessity and influence of pre- and post-rolling homogenisation process on Al–6Mg alloy properties, series of experimental investigations were carried out on direct chill (DC) cast Al–6Mg. Hot extrusion at the temperature of 350°C has been selected as a pre-rolling homogenisation process, which leads to homogenisation by formation of partially recrystallised grains. Cold rolling performed on both DC cast and hot extruded samples up to 80%. Post-rolling homogenisation process done by annealing at 350, 450 and 550°C. Results show that pre-rolling hot extrusion is effective for stability of mechanical properties after cold rolling. Good combination of strength and ductility is achieved for the cold-rolled sample followed by annealing at 450°C. Changes in strength and ductility of the alloy after both pre- and post-rolling homogenisations are controlled by recovery resulting from dislocation arrangement and formation of subgrains. Both pre- and post-rolling homogenisation are effective in improving mechanical properties of cast Al–6Mg, however post-rolling process is more effective if the annealing temperature is chosen correctly.

KEYWORDS:

• Al–6Mg
• cold rolling
• tensile properties
• recovery
• subgrain

Acknowledgment

The authors wish to thank the research board of Shahid Beheshti university and Sharif university of technology for providing research facilities used in this research.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.