Natural ageing (Topic: 10046)

The heat-treatable alloys change properties when stored at room temperature after solution heat-treatment and quenching. This is called "natural ageing". The rate of change varies with alloy group and also within an alloy group, so that natural ageing to a stable condition may require from a few days to several years. For some 7000-alloys this hardening is very marked and they might reach maximum strength after a month at room temperature.