Cooling the metal is just as important as the other steps involved in heat treatment in Gastonia, NC. It determines the strength and heat tolerance in the metal, and that can fall along a wide range. The way metal is cooled can determine those elements and often is the deciding factor in whether a metal will have the needed properties. Here are the five ways to cool metal after heat treatment, and the intended results of each approach:
- Furnace: When metal needs to cool slowly, it is left in the furnace to cool on its own. This is often part of the annealing process, which improves strength, reduces residual stress and refines steel grade. Stress relieving is particularly desired when components already underwent harsh conditions and were slow cooled before to prevent damage. Using furnace cooling is a precaution, since the intention is to cool the metal in a way that reduces the possibility of compromising it. Cooling metal suddenly or quickly can damage it and render it useless for future applications.
- Water: Quenching is quick cooling by submerging metals into liquid. Water is the quickest quenching method. Sometimes, it is mixed with other organic material to help the process. Water is a favorite because it is economical and non-flammable. However, you never want to use water cooling if the material faced stress before, as it can cause the metal to fracture. Tempering and other heat treatment processes that allow for more flexibility often end with a quench in water. This is often reserved for the hardest materials that have not responded to heat treating previously.
- Oils: Quenching oils have a high boiling point and a controlled cooling process. This makes them a favorite with steel. When used with steel, quenching oils do not cool as quickly as water, which is an advantage for hardening alloys. This prevents distortion and cracking that requires heat treatment to start over again. The only disadvantage is that, unlike salt-based liquids or water, quenching oils are messy to handle. Considering that they are also flammable, any technician using quenching oil must take extra care of the workspace.
- Brine: This is essentially salt water. Brine offers a wide temperature range, and it is less sensitive than other quenching liquids. It allows more cooling control than water, but it works a little quicker than oil. If furnace cooling is too slow, but cooling cannot happen too quickly, brine is the perfect middle point.
- Liquid salts: Similar to brine, liquid salts do not have water as the primary element. The best way to characterize it is as a thick salt water. It offers high tolerance, and without too much water, it can be controlled by just adding salt up to the point of quenching. Liquid salts cool quicker than brine and work best when the priority is hardening.
If you are interested in hiring a local company for heat treatment in Gastonia, NC, contact J. F. Heat Treating, Inc. We look forward to helping you with your project.