Metal Needs To Be Tempered To Make It Stronger

Posted on: 1 October 2015

Metal is a fairly strong material. However, it can be prone to cracking and breaking when it undergoes certain processes, which can include bending it and trying to form it into a new shape. That can mean that the metal becomes useless to a particular business. However, there are processes that the metal can undergo which will make it possible to work it easier and even make it stronger. One of those processes is called tempering. 

What Is Tempering?

Tempering metal means that the metal is heated up to a certain temperature or a particular color, and then cooled. For example, the metal may need to be heated up to a red-hot stage. That means that the metal is glowing red. When the metal reaches that particular color or temperature, it is then quickly cooled, or quenched. That usually happens by submerging the metal in a cold liquid, either water or oil. The rapid temperature change is what tempers the metal. The tempering process may need to be done a few times in order for the metal to reach the right strength. 

Why Does Tempering Make Metal Stronger?

It may seem counter-intuitive that heating metal makes it stronger since extreme heat will melt metal. However, the temperature at which tempering happens isn't enough to melt the metal, it's just hot enough to get the molecules inside the metal moving and flowing. That allows the molecules inside the metal to form a crystalline lattice that they would not otherwise have. That lattice is what changes the grain of the metal and the stress lines in the metal, which allow the metal to have a higher tensile strength and keeps it from breaking when it is being bent and worked. Quenching the metal, causing that rapid temperature change, is what allows the crystalline lattice to stay in place. Once that lattice has been set into place, it won't change. 

Metal may be strong, but after the tempering process it is even stronger. Tempering metal is something that's been happening for thousands of years. Blacksmiths have done it by hand, heating the metal up in their forge and sticking it into cold water to quench it, to make sure that the things they make are strong enough to be worked. Now metal fabrication companies do it on a larger scale but still use the same basic process, making sure that metal can be formed into whatever shape is necessary. 

For more information, contact a company like Pacific Metallurgical Inc.