Heat treatment occurs at the end of the forging process to change the properties of the forged steel. The type of heat treatment performed is determined by the end-use application of the item. We offer several types of heat treatment at FRG:
Quenching and Tempering
Quenching is a process used to harden steel and help it to resist wear by reducing the crystal grain size. To do this, the metal is first heated to a specified temperature and then held there for a certain amount of time. After being held at that temperature, the steel needs to be rapidly cooled, which happens during the quenching process. Once it’s quenched, the steel is washed, and then the tempering process begins. This needs to be done quickly to avoid deforming or cracking the parts. This cooling process occurs by submerging the item in liquid, usually water or oil. At our facilities, we use oil to quench our items, followed later by a wash in water to remove the oily residue.
Annealing is a form of heat treatment that will soften the metal, improve grain structure, and relieve internal stresses. To perform this, the steel is placed in a furnace large enough for the heat to completely circulate around the item. Once it has reached a specified temperature, the steel is then slowly cooled by turning the furnace off. Other cooling options include placing the item in a low heat conductivity substance, such as sand or ashes.
The process of normalizing steel is similar to annealing, but the main difference is that the normalizing process includes heating the steel to a much higher temperature. Normalizing the steel makes the item better for machinability and also refines the grain structure. Once the steel is heated to the specified temperature, it is then air-cooled until it reaches room temperature.
Normalizing and Tempering
Normalizing is typically cooled by air, but there are instances when the cooling process needs to be altered. In these cases, the normalizing process is done, and then it is tempered within a furnace. This allows us to control the cooling time and adjust it so the metal hits a specific hardness range.