Exposing different metals and alloys to heat creates a change within the metal that can be essential to developing or enhancing specific properties or characteristics. Most commonly used for steel, the normalizing heat treatment process can be simply described as heating the steel to a specific temperature for a specific amount of time.
During this heating process, the desired transformation of the steel occurs and is allowed to continue until the correct point by maintaining the heat. Cooling is then done through air cooling, which is also a critical part of the normalizing heat treatment. By allowing the steel to air cool, there is no further transformation of the properties and characteristics of the steel that would occur with rapid types of cooling or quenching types of processes.
The Results
By using the normalizing method, the microstructure of the steel changes. This resulting change will add to the hardness of the steel as well as providing greater strength. At the same time, this process also lowers the ductility of the steel, which will make it much easier to work with and machine in future applications.
One of the important changes in the microstructure of the steel is the change in the pearlitic structure. Think of this as the grains in the steel. With the annealing process, which is also an effective and common heat treatment options, the pearlite structure is coarser. Through normalizing, the pearlite is finer and more uniform, which provides greater overall strength to the steel.
However, even though the normalizing heat treatment may be used to prepare the steel for machining, it can also be a final type of heat treatment for some applications. It is a very common process for many Original Equipment Manufacturer parts and components that is effective, low cost and provides the required enhancement to strength and hardness.
