The term annealing refers to a heat treatment in which a materialis exposed to an elevated temperature for an extended time period and thenslowly cooled.
According to ASTM, annealing is defined as a softening processconsisting of heating the steel to a temperature at or near the critical point,holding there for a proper time and then allowing it to cool slowly in thefurnace itself.
Three stages of annealing process (or Annealing cycle): Any annealing process consists offollowing three stages:
1. Heating to the desired temperature.
2. Holding or 'soaking' at that temperature.
3. Cooling or 'quenching', usually to room temperature.
In practice, annealing is one of the most widely used processes inthe heat treatment of iron and steel.
Generally annealing is carried out to achieve one or more of thefollowing purposes:
1. To relieve or remove stresses.
2. To induce softness.
3. To alter ductility, toughness, electrical, magnetic, or otherproperties.
4. To refine grain structure.
5. To remove gases.
6. To produce a definite microstructure.
Annealing process is employed in casting, forging, rolled stock,press work, etc.
The most common types of annealing processes applied to commercialsteels are:
1. Full annealing,
2. Process annealing,
3. Stress relief annealing,
4. Recrystallisation annealing, and
5. Spheroidise annealing.
Price: