Precipitation step after solution treating, in which fine particles form inside the grains and block dislocation movement. Natural aging happens at room temperature (the T4 temper in aluminum); artificial aging in an oven, about 120 to 190 °C for aluminum or 480 to 620 °C for 17-4 PH, gives peak tempers like T6 and H900. Overaging past the peak trades strength for toughness and stress-corrosion resistance.
Fresh 2024 rivets start aging at room temp, so they go in the freezer if they aren't driven within twenty minutes.
Also heard as
- ageing
- age hardening
- artificial aging
- natural aging
Related terms
Solution treating
Heating an alloy to dissolve its strengthening elements into one phase, then quenching to trap them there.
Precipitation hardening
Strengthening an alloy by forming very fine particles inside its grains through solution treating and aging.
Tempering
Reheating hardened steel below its lower critical temperature to trade some hardness for toughness.