Annealing is used to soften steel, improve machinability, refine grain structure, and relieve residual stresses produced during rolling, forging, welding, or cold work. In many steels, controlled slow cooling converts austenite into ferrite and pearlite, resulting in lower hardness and improved workability.
For cold-worked materials, annealing can restore ductility by recrystallization. For higher-carbon steels, special annealing cycles, such as spheroidize annealing, are used to convert
lamellar carbides into spheroidal carbides, improving machinability and preparing the material for subsequent hardening.
At Braddock, annealing would be selected when the engineering objective is not maximum hardness but a stable, machinable structure before subsequent forming, machining, or hardening.
Annealing is commonly applied to steels and other alloys that require reduced hardness or stress relief before downstream processing.
Full annealing generally involves heating above the critical temperature to make the steel austenitic, followed by slow furnace cooling. For many carbon and alloy steels, the annealing range is roughly 1200°F to 1650°F, depending on composition and the type of anneal being performed. Soak time must be sufficient to equalize temperature and produce the intended structure through the section.
During slow cooling, transformation to ferrite and pearlite occurs at relatively low rates, yielding a softer microstructure than would be produced by air cooling.
At Braddock, the important technical variables would be annealing temperature, hold time, cooling rate, and whether the required result is a full anneal, process anneal, or spheroidize anneal. Those choices determine final hardness, carbide morphology, and machinability.
