Steel aging

Aging is the evolution over time of material properties at temperatures close to room temperature.

Metals, and steels in particular, are made up of grains whose crystalline structure is highly stable and can only be modified by high-temperature phase transformations or precipitation of compounds, generally above 500°C. As a result, the properties of steels do not normally change over time.

There is, however, a phenomenon of property evolution at low temperatures linked to the diffusion of mobile interstitial carbon and nitrogen atoms under certain conditions: this phenomenon is known as steel ageing.