Carburizing

In carburizing, the surface hardness of the steel is increased by adding carbon to the component. The component that requires hardening is heated and exposed to a carbon environment. The carbon penetrates the surface of the metal and strengthens it. The agent used can be solid, liquid or gas. The initial investment costs are generally higher than other processes. In liquid carburizing, it is difficult to control the depth of hardness and it may not be uniform throughout the object. This process must be carried out in a controlled environment to prevent oxygen from being present in the process which changes the outcome of the metal hardening. Partial vacuum processes shorten the time involved and provide a few economic advantages of case hardening.

Gas Nitriding

With this process, the material is heated and then exposed to atomic nitrogen, which can penetrate the steel or iron. Atomic nitrogen reacts with the metal to increase its hardness and resistance. This process offers a high degree of hardness, but cannot be used with all of the alloy steels.

Following this process, there may additional manufacturing costs in the form of an expensive grinding process to remove the thin white layer which forms on the surface. However, there are no other heat processes which follow nitriding, which means less deformation to the object.