capabilities > Heat Treating > Carburizing and Case Hardening Solutions


Raw, untreated steel is pliable and soft all the way through — when you need a part to be hard at the surface but strong and ductile in the middle, carburizing and carbonitriding are optimal case hardening solutions.

Case Hardening Solutions to Meet Your Exact Specifications

Carburizing is a case hardening process that adds carbon to the surface of various alloys, giving the material a hard, wear-resistant outer layer while preserving a softer, more ductile core that is better able to respond to stress without cracking. Processes like carburizing allow manufacturers to work with softer materials and still meet basic requirements for hardness required by an application. While it doesn’t add material strength, it does effectively increase the hardness of the outer layer of the material, making it more wear-resistant than it would otherwise be. This is achieved by diffusing carbon into the surface of the alloy after manufacturing.

Common Case Hardening Applications:
  • Fasteners
  • Bearings and Gears
  • Engine Parts
  • Screw Machine Parts
  • Cutting Tools

Broad Capabilities for a Wide Range of Projects

At Paulo, our furnaces are designed to handle a broad scope of case-hardening applications. We can harden parts up to 48 inches by 36 inches by 36 inches.

We can handle parts up to 48 inches by 36 inches by 36 inches and 3,000-pound loads, allowing us to harden up to 3,800 pounds per hour.

The kind of furnace we use depends on your application. We have both continuous belt furnaces and integral quench furnaces to meet the needs of any project. Some parts may have to be heat-treated for hours or even days to accomplish the required case depth, which is why we can operate 24/7 to meet project demands.


Another case hardening process is carbonitriding. Parts are heated to around 1,600 degrees Fahrenheit in a sealed chamber before nitrogen and carbon are added. Because the part is heated into the austenitic range, carbon and nitrogen atoms diffuse into the part.

Nitrogen is commonly added to low-carbon, low-alloy steels to help a part maintain hardness during use in high-heat settings.

Process Control

Process control during case hardening is critical, especially for parts with thin sections or irregular shapes, which are at risk of through casing. To avoid this, case depths should be carefully measured after treatment to determine whether the part will perform as designed.

There are two types of case depth: 

  • Total case depth is the total distance carbon, nitrogen or both have diffused inward from the surface of the part. Total case depth is usually measured visually by examining a part’s cross section under handheld microscopes. Measuring total case depth is typically specified for parts requiring thinner cases.
  • Effective case depth is the distance inward from a part’s surface to a specific hardness. It’s meant to measure whether an intended hardness has penetrated to the correct depth. Microhardness testing methods are used to determine effective case depth.

Technology-Driven for Consistent Results

Paulo’s decades of experience, high-tech processes, and thorough understanding of metallurgy ensure your parts meet your exact specifications, with thorough testing and inspections and a fast turnaround to keep your line rolling.

Our state-of-the-art facilities are equipped with automation and are designed to handle a broad scope of case hardening applications. Our furnaces are self-controlling with heat tracking throughout the process to maintain conformity and consistency. We have both continuous belt furnaces and batch integral quench furnaces. Some parts may require heat treatment for hours or even days to accomplish the required case depth, which is why it’s important that your heat treating partner has the capacity to operate 24/7 when necessary.

Advance your carburizing results.

We’re ready to tackle your next project. Request a quote, or contact us today learn more about our approach to case hardening.

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