Heat treatments are designed to improve the strength, flexibility, durability and hardness of metal products without actually changing their shape. Annealing is an umbrella term for one type of this heat treatment, which reduces hardness, relieves internal stresses and improves ductility.
What is annealing?
The process of annealing uses thermodynamics to achieve its goals. By heating up a metal to a certain temperature, it breaks bonds and moves atoms around within the metal, which relieves internal stresses by removing metal dislocations. This is usually conducted in a large oven that allows the heated air to circulate around the metal part. Some are left to cool down slowly in the oven, while others undergo other cooling processes like a soak in water or brine, which can help increase hardness.
Metals undergo three different stages during the annealing process: recovery, recrystallization and grain growth:
- Recovery: In the recovery stage, the metal is heated, which softens and removes dislocations and internal stresses.
- Recrystallization: The recrystallization stage allows the metal grains to grow and replace where the dislocations and internal stresses once existed.
- Grain growth: If the annealing process continues past recrystallization, it proceeds to the grain growth stage. At this point, the microstructure of the metal becomes coarser, and the metal may lose some of its strength.
Since annealing is an umbrella term, there are actually several different subtypes of annealing, all of which accomplish different objectives.
When would I use annealing?
In a broad sense, annealing in Gastonia, NC is a process that’s used to soften metal, relieve stress and improve ductility—but what does that mean in practical terms? You might use annealing to soften metal for coldworking purposes, for example, since coldworking can render metal more fragile than before it was manipulated.
Annealing also improves machinability, or the ability for machines to flatten and work the metal, and can even improve electrical conductivity.
Basically, when you’re working with metal, overworking the metal can make it very hard and brittle, prone to cracks and breakage. Annealing allows the structure of the metal to change and regrow at the atomic level, softening the metal and relieving stress so that it can continue to be worked without fear of damage. This method also helps ensure that your finished product won’t break during use, either.
Annealing services in Gastonia, NC
J. F. Heat Treating Inc. has been providing professional metallurgical services to the Gastonia area since 1980. We’re pleased to offer cutting-edge tools and equipment, operated by highly trained technicians with years of industry experience. Whatever the size and scope of your project, our talented team can use heat treatments, including annealing, to strengthen, soften or improve the ductility of your metal parts. Not sure what kind of heat treatment might be right for your products or parts? We would be happy to discuss your options when you call or stop by to tell us about your project. Reach out to us today to learn more about our processes and what we can do for you.