Within several steel and other metal types, abrasion and indentation resistance are vital attributes for required applications. Both these attributes trace back to metal hardness, particularly on the outer surface, and a process called case hardening is sometimes used to ensure a given metal substrate is hard enough for a given application.

At Wasatch Steel, we’re happy to offer a wide range of steel products, plus expertise on how various processes will impact their qualities, including hardness. In this two-part blog, we’ll go over everything you need to know about the case hardening process for steel and other metals, including why it’s done, how it’s done and the methods that can be used to carry it out.

Case Hardening Basics

As we noted above, case hardening is a material processing method that helps increase the outer surface hardness of a given metal. Essentially, it adds a new layer of metal to the existing one, a layer that’s extremely thin but also makes the outside of the metal much harder than it was previously.

To perform case hardening, elevated temperatures will usually be required. In some cases, rather than simply adding to the exterior surface, this process also alters the crystal structure of the metal in significant ways. The process will limit formability and machinability, meaning it’s usually done after other fabrication processes have already taken place.

Why Do It?

Why might a given steel or metal material require case hardening? There are a few potential reasons, the first being efficiency. It takes less energy and time to heat just the outermost section of a metal compared to its entire cross-section and body, and this savings can be a huge factor for many in major manufacturing areas.

In other cases, though, case hardening will be used to increase metal performance quality. There are several applications where a hard exterior with a softer, more ductile interior is valuable, such as when a metal needs to be able to resist abrasion while still absorbing impact without fracturing.

Types of Metals

Generally speaking, the types of metals that can be put through the case hardening process are limited to those that are ferrous. There are a few exceptions here involving titanium or aluminum alloys. Metals that can be case-hardened include:

• Low carbon steel
• High carbon steel
• High strength, low alloy steel
• Tool steel
• Various stainless steels
• Cast iron

You’ll typically see case hardening used for materials like gears, rods, camshafts, pins, fasteners and related products that require a combination of hardness and interior ductility.

For more on the case hardening process in steel and other metals, or to learn about any of our steel products or services, speak to the staff at Wasatch Steel today.