Characterisation of precipitation upon cooling of an AA2618 Al–Cu–Mg alloy

• Two types of precipitation are monitored upon cooling of an AA2618 Al–Cu–Mg alloy.
• Precipitation above 300 °C occurs at cooling rates lower than ca. 17 K/s.
• Below ca. 300 °C, Cu–Mg hardening clusters form upon cooling at 0.03–100 K/s.
• The precipitation domains in AA2618 are summarised on TTP and CCP diagrams.
• The importance of hardening is highlighted for quench-induced stresses prediction.

The precipitation of an AA2618 Al–Cu–Mg alloy is monitored during isothermal holdings and continuous coolings. The Time-Temperature-Property and Continuous-Cooling-Precipitation diagrams of AA2618 are obtained using in-situ resistivity and differential scanning calorimetry respectively. The two precipitation domains observed at high temperature and low temperature (<300 °C) are discussed with regard to their influence on the mechanical properties during quenching of large components.

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