What Is Carburizing, and When Would I Need It?

Exploring the different metallurgy processes in Gastonia, NC is helpful when deciding which treatments would best suit the parts or components you’re creating. Carburizing, also known as case hardening, is a process that achieves a wear-resistant exterior while maintaining the strength and character of the interior.

How carburizing works

Carburizing is usually used on parts after they’re machined. Most of the time, low carbon steel and high steel alloys are suitable for this heat treatment process. Carburizing diffuses and distributes carbon across the part’s surface, which is responsible for creating the tough exterior “case.”

The components are heated in a large enclosure—usually a pit or sealed atmosphere furnace—at which point carburizing gases are introduced to the environment. This allows a precise temperature and gas control. Carburizing primarily depends on heat and time to achieve the hardened steel exterior case, so the operator has to adjust the time depending on how deep they want the carbon to penetrate.

After the case is created, there are two cooling options. First, the operator can slow-cool the parts to perform quench hardening later. Second, they can quench the product immediately in hot oil, which minimizes the shape distortion, although this method may not be useful depending on the strength needed for your components.

Carburizing always involves some level of shape distortion, due to the nature of the process. When the parts are heated and then cooled, changes in volume as well as grain growth can occur. Compared to other metallurgical processes, however, carburizing produces less distortion than most. These shape changes are usually addressed by post-carburizing grinding, which restores the part to its originally intended size and shape.

When you can benefit from carburizing

Carburizing can be used for parts of a number of different sizes and shapes, from small gears to parts weighing up to 50,000 pounds. Typically, this heat treatment process is used for components or products that will see a lot of impact or wear and tear over time, like scissors, swords and machine gears.

Carburization provides a very hard surface with a malleable interior, making it easier to form the parts into your desired shape. If you’re trying to harden a very intricate part, like internal machine components, carburizing can provide the results you’re looking for.

It’s also a relatively inexpensive process, compared to producing other steel alloys—you’ll get similar results for much less. Carburizing lets you harden the steel first and then shape the material, rather than machining the products first and then hardening them. This keeps the price down and allows makers to create parts from less expensive materials.

When you’re looking for a company that can perform the full range of metallurgy processes in Gastonia, NC, J. F. Heat Treating Inc. is here to help. We’ve been helping clients repair and enhance their metal components since 1980. No project is too big or too small—get in touch with us today to learn more about our processes and what we can do for you.

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