An In-Depth Look At The Complexities Of Metal Annealing

Posted on: 21 April 2020

For the most part, people think of metal annealing as a simple process. However, it is actually far more complex than most people imagine. In general terms, annealing is a heat process done to certain materials to either increase or decrease density or hardness or bring about some type of desirable attribute. Here is a look at why the annealing process is a bit complicated. 

The metal has to be heated up in a uniform fashion. 

When annealing is done to a piece of metal, the process has to be done in a uniform fashion. In other words, all parts of the metal really need to receive the heat application at the same time. It requires special equipment and experience to achieve this, especially if you are working with a large piece of metal. If the metal is not heated uniformly, some parts can receive more heat than others, which would compromise the uniformity of the end result. 

After annealing, the metal has to be cooled slowly most of the time to avoid structural deficits. 

Quenching is the term used to describe the process of bringing a piece of annealed metal back down to room temperature, and there are a lot of ways that this can be accomplished. To achieve certain types of annealing, rapidly reducing the temperature of the metal may be done. However, this drastically changes the crystalline structure and grain of the metal, which is only desirable in very unique applications. In general, it is best if quenching is a slow process; there are no drastic changes and efforts may be taken to slow down the temperature drop. For example, an annealing service professional may use a series of heaters to gradually lower the temperature degree by degree over the course of several hours. 

Annealing processes have to be adjusted according to the metal. 

Regardless of what type of annealing process is being performed, all respects of this process have to be adjusted according to the type of metal you are working with. For example, something like brass tends to accept annealing better if it is done by holding the piece at a high temperature for a certain prolonged period of time. Yet, something like an aluminum piece has to have lower heated applications and may not sustain high levels of heat for long periods. It takes an incredible amount of hands-on experience to get familiar with how different types of metal react during annealing.