Understanding and Preventing Steel Decarburization, Part 1

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Understanding and Preventing Steel Decarburization, Part 1

understanding preventing steel decarburization

When it comes to specific elements that play a big role in the properties of a given steel or metal product, carbon is at or near the top of every list. Carbon helps dictate everything from mechanical properties to formability and numerous others, and its content within steel – or lack thereof – is one factor to keep an eye on.

At Wasatch Steel, our custom steel experts will be happy to guide you through carbon basics for any of our steel products, from steel tubing to steel bar, steel pipe and many other varieties we offer. One steel process to be aware of within this realm is known as decarburization – what is steel decarburization, how can it be measured for, and how can you remove or prevent it from taking place on your steel materials? This two-part blog series will cover everything you need to know here.

Decarburization Basics

As the name indicates, decarburization is a process that involves the carbon content in a piece of steel being reduced. The most common form of decarburization takes place when steel is heated above the limit for its recrystallization temperature, which for most steel types sits somewhere in the range of 700 degrees Celsius.

Exposure to these temperature ranges also brings in gasses like hydrogen and oxygen, and this is where the decarburization process begins. The carbon within the steel bonds itself to these gasses, leaving the steel with less carbon than it had before. Because these gasses are only in contact with the surface layer of steel, decarburization is mostly seen on these same outer layers, and rarely in deeper sections.

Impact of Lost Carbon

Why is this a problem? Well, because as we noted earlier here, carbon plays a major role in several important characteristics of steel.

In particular, losses of carbon within steel lead to several mechanical properties being lower-grade than before. Elements like hardness, strength, crack resistance and formability can all be negatively impacted. Fatigue strength is often impacted particularly heavily, as is hardness. In nearly all cases, this is not a desirable process for steel to go through.

Testing for Decarburization

Decarburization is a process that must be tested for – it cannot be picked up through visual means only. The most common method here involves measuring the hardness of the steel before a thermal process is performed on the steel, then taking this same measurement again once the process is finished. This will help give an indication of how much decarburization has taken place, if any.

Another method here involves cutting a piece of the steel off and examining it under a microscope. In this case, the viewer can see not only if decarburization has taken place, but also how deep it has gone.

For more on steel decarburization, or to learn about any of our steel services or processes, speak to the staff at Wasatch Steel today.