Annealing is the process of heating a metal to change its hardness and strength. When this procedure is done properly, metal reduces its cold working properties and becomes more flexible, stress-free. To obtain these properties, it is heated to temperature that is less than its melting point and then slowly frozen. Generally, Ferrite sub-critical annealing, Austenitic annealing are the most commonly used heat treatments for industrial steel.
The machinability requirements of steel are different and thus, this process is used to maximize the properties of steel in order to meet the specific requirements.
Stages of the Procedure:
The process is conducted under three stages:
1 Recovery Phase
3 Grain Growth
The environment which is required for this process to occur is extremely significant, as during the procedure, the material needs a carbon rich atmosphere facilitating carburization.
Types of this Heat Treatment Process:
Below are the various types of this heat treatment process
1. Process Annealing
2. Full Annealing
3. Stress Relief
Process Annealing: It generally suits for low carbon steel and is mainly passed on cold rolled steel such as wire drawn steel and so on. It helps to enhance the characteristics such as ductility and hardness.
Full Annealing: The steel involves heating to about 30 to 50 degrees centigrade above a important temperature of the material. The temperature is then holed for a specified time period and then inside a furnace the material is allowed to cool without any forced ways of cooling. It can be applied to castings made from high carbon and medium steels, hot worked sheets and forgings and so on.
Stress Relief: It can be used for large welded structures and castings.
Isothermal & Spheroids: High carbon and alloy steel use the Spherodise method and isothermal procedure is mainly appropriate for alloy steels and for low carbon.
Below are some of the advantages of this heat treatment process:
- Improves and enhances the machinability of the steel
2. The ductility of the steel can be amplified
3. The steel is softened by the procedure
4. It augments the toughness of the steel
5. The homogeneity of the steel can be improved
6. It refines the grain size of the steel
7. It further prepares the material for other heat treatment
Furnaces for Annealing:
Stainless steel annealing concentrates on the entire piece, hence the advantage of placing it in a furnace. Annealing furnaces can range in size and function significantly.
As with other types of metal work, both amateurs and professionals practice annealing. But there is a point when amateur work, however good, is inappropriate. If a work-piece impact people’s safety when it is implemented in a final process, a professional should anneal it. Although the purpose of annealing is to soften metal, making it too soft or leaving it too hard could have critical consequences.