Effect of Low Cu Addition and Thermo-Mechanical History on Precipitation in Al-Mg-Si Alloys

Abstract:

The effect of cooling rate after solution heat treatment and its combination with 1% pre-deformation on precipitation hardening in two Al-Mg-Si alloys is investigated by transmission electron microscopy (TEM), and related to material hardness. Two alloys have been used, one Cu-free and the other with low Cu additions (~0.1 wt%), both having the same amounts of other solutes. A double peak hardness evolution during an isothermal heat treatment was observed with slow cooling after solution heat treatment. This effect was less pronounced in the Cu-added alloy. The 1% pre-deformation also made this effect less pronounced, but it led to faster initial hardness evolution and delayed over-aging. Maximum hardness was not influenced by cooling rate and the pre-deformation. Hardness was directly related to precipitate number densities.

• Periodical: Materials Science Forum (Volumes 794-796)
• Pages: 1014-1019
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.794-796.1014
• Online since: June 2014
• Authors: Takeshi Saito*, Calin D. Marioara, Jostein Røyset, Randi Holmestad
• Keywords: Al-Mg-Si Alloy, Deformation, Precipitation, Quench Sensitivity, Trace Elements, Transmission Electron Microscopy (TEM)

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