Heat Treatment Information


This process uses a generated atmosphere of Carbon Monoxide that is nearly free of Oxygen and Nitrogen. When heating Steel in this atmosphere Steel absorbs additional Carbon making the material harder. This process also utilizes quenching, rather than air cooling, to achieve maximum hardness.

While this process produces a very hard outer surface of the Steel the process of absorbing Carbon does not penetrate very deeply into the item typically, 0.010” to 0.015” in most Carr Lane Mfg. applications. (Depths up to 0.030” are possible.) The main consequence of this thin layer is that it cannot be measured (hardness or depth) using a Rockwell or Brinell Hardness tester. It can only be inspected after sectioning the item and utilizing a microscope.

An additional aspect of Carburization is that this exterior layer is so hard that it cannot be measured using the Rockwell scale; only a Vickers tester is capable of measuring the hardness of this outer layer.

Most common applications for this process are items which must have excellent wear resistance as the Hardness of the outer layer of these items is far greater than that of a Through-Hardened item.

Inspections of both Carburize depth and hardness are routinely performed at Carr Lane Mfg., please contact us to discuss your specific application or concerns.


This generic term describes the process of “Tempering” and “Quenching” materials. While the process, temperatures, times, and quench fluids vary based upon the material being Heat Treated, the result is similar for all materials.

Unlike the Carburize process, this process results in increased Hardness of the material regardless of “depth” ergo; “Through-Hardened.” All Carr Lane Mfg. items that undergo this process do so to improve not only the Hardness and Wear characteristics of the material but also to improve the material strength.

These items are typically measured using a Rockwell tester and measured on the “C” scale. They do differ from material to material. Please contact us to discuss your specific application or concerns regarding this process.

Rockwell Hardness Test

Patented by two Americans in 1914, the process produces an indentation in the material being measured under a load. The Tester measures the depth of penetration of the indention tool. This process is quick and efficient and is used by Carr Lane Mfg. to inspect the hardness of all Through-Hardened materials.

Vickers Hardness Test

Unlike the Rockwell Test, the Vickers Test has many similarities to the Brinnell Hardness Test method. Unlike other methods in indention tool is a pyramidal diamond of very small size. The unique shape of the indenter allows consistent test results regardless of force, if the force meets a minimum threshold. The diamond material of the indenter ensures that very hard materials, harder materials than can be measured on a Rockwell tester, can be measured. This process is used by Carr Lane Mfg. to inspect the depth and hardness of all Carburized materials.