Term in the field of heat treatment.
After the casting has reached the respective treatment temperature, it is “held” at this temperature for a certain amount of time. In this case, the holding time or holding period refers to the time span.
An example for the influence of the hold period (aging duration) on the mechanical properties of the Al Si9Cu3(Fe) alloy is shown in Fig. 1.
Additional references:
Heat treatment of hardenable aluminum alloys
Hardening
Tempering, Hardening and tempering