Heat-treatable alloys (Topic: 10054)

Both the yield strength (Rp0,2) and the ultimate strength (Rm) of the fully age hardened 6000-alloys will start to fall rapidly when held at temperatures beyond ‰100°C. Rp0,2 decreases to about one tenth at 300°C compared to the value at room temperature (see figure). This is the strength after long time exposure at elevated temperature and is dependent on both holding time and temperature.

Another type of properties is the strength at room temperature after different exposing times at elevated temperatures. Exposure to high temperatures for shorter or longer times will of course affect the resulting room temperature strength of a 6000-alloy in the same way as ageing does. Every stay at high temperatures will additively drive the ageing further and thereby overage the material (see diagrams for AW-6063 and AW-6082 after 1Ý000 h exposure).

The room temperature properties of the 6000-alloys appear to be maintained even after 1Ý000 or 10Ý000 h exposure up to ‰150°C, while testing the material at elevated temperatures make the strength continuously diminish, at first gradually, then rapidly as the temperature is increased.