Holding a load at temperature after the furnace reaches setpoint, long enough for the core to catch up and for carbon and alloy to go into solution. Soak time depends on section size, load density and grade: plain carbon steels need little, while high-alloy tool steels need time for carbides to dissolve. Too short leaves soft cores; too long wastes furnace time and invites decarburization and grain growth.
Load's at heat, start the soak clock now, ninety minutes and then drop it.
Also heard as
- soaking
- hold
- soak time
Related terms
Hour per inch
Heat-treat rule of thumb that a part needs about one hour at temperature per inch of its thickest section.
At heat
Shop phrase meaning a load has reached its setpoint temperature, so its soak time can start counting.
Austenitizing
Heating steel above its upper critical temperature and holding it until the structure becomes austenite.
Decarburization
Loss of carbon from the surface of steel during heating, leaving a soft skin that will not fully harden.