There are 2 main types of heat treatment: annealing treatments and hardening treatments.
Annealing restores the material to as soft a condition as possible (least work hardened).
In hardening, heat input is used to harden the material. Depending on the alloys, we apply quench hardening or ageing hardening (or precipitation hardening). Quench hardening requires a high heat input followed by very rapid cooling (within a few seconds).
Ageing hardening uses a low heat input but over a very long time (several hours).
In both these hardening scenarios, the aim is to generate stresses inside the material stretching the atomic lattice, and their ease of movement.
Heat treatments:
- Alter the hardness and mechanical characteristics of the alloy
- Alter the grain size of the material
- Alter the structure of the various alloy phases
- Generate surface oxidation
- May deteriorate the surface condition of the strip