Expression used in heat treatment, describing the duration of holding (s. Holding) the heat treatment material at holding temperature.
In general, the holding period is measured from the point when the heat treatment material reaches the target holding temperature; please note, that the furnace temperature (furnace space temperature) may be higher. For measuring the temperature, a thermal element is inserted that maps the relevant wall thickness. The temperature of this thermal element is used as reference value.
Figure 1 illustrates the temperature curve for T6 heat treatment of a Al-Si7Mg0.3 gravity die cast part, the hold period only starts when the cast part reaches the target temperature, the heat-up time is not included in the holding period.
Heat treatment of hardenable aluminum casting alloys