Cooling is a final step in heat treatment in Gastonia, NC. Much discussion of heat treatment is centered on the ways in which heating materials will change the composition, but cooling is just as essential to the process of getting the end product you expect. The rate at which materials are cooled also determines the properties of your components, and mishandling this step can cancel out the entire heat treating process. These are the cooling techniques often used in a heat treatment shop, and a general description of when they might apply:
- Furnace: For a slow rate of cooling, material is left in the furnace to cool on its own. This is often used for annealing, which improves strength, eliminates residual stress and refines the grain of steel. Stress relieving, which is done on components that have already undergone harsh conditions, also ends with slow cooling in order to prevent further damage. The intention is to avoid further damage to materials that already underwent stress, as a quick cooling process can compromise the advantages added by heat treatment by adding another harsh condition.
- Brine: Brine is ordinary salt and water. It is part of the type of cooling known as quenching, which forces quick cooling through submersion in a liquid. Brine is a common quenching material because of its wide temperature range; it is not as sensitive as other quenching liquids. It also allows for more cooling control, which is important when the slow cooling effect of a furnace is not quick enough to get the needed properties, but it cannot happen too quickly, either.
- Liquid salts: This quenching liquid is like brine, except water is not the overwhelming element. It also has high tolerances, and without the presence of water, the only step in maintaining liquid salts is to add more salt when it is time. This quenching liquid cools quicker than brine, and works best for hardening projects.
- Oils: Quenching oils are used primarily for steel, due to their high boiling point and controlled cooling properties. Steels quenched in oils will not cool as quickly, which is an advantage for hardening alloys. This cooling process prevents distortions and cracking that can require the heat treatment process to be started again. Its only disadvantage is that quenching oils can be messy, unlike the salt-based liquids, which wash off easily.
- Water and organic material: Water, and water mixed with organic material, offers a cooling effect that is very fast but clean. It is also non-flammable and economical. The problem with using water is that it must be used for those applications that are not applied to already pressured material. Cooling these materials with water can cause damage and fractures. Tempering and other processes that provide flexibility can normally end with a quench in a water or water-based material.
If you are looking for quality, effective heat treatment in Gastonia, NC, contact J.F. Heat Treating Inc to harden and carburize your metals. We will use our skills and knowledge to provide the best material for your industry.