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Case hardening

While there are many tough metals on the planet being mined and manufactured daily, steel alloys are still the hardest of all.

If you're looking to build strong materials that last for a long time while retaining their interior character, case hardening is the perfect process. Case hardened steel is one of the strongest metals you can work with for any application.

Here is why you should choose case hardened metal and how the process works.

Why Choose Case Hardening?

Case hardened steel offers several benefits to the durability and longevity of the product you're hardening. When objects need to have a hard exterior to deal with everyday wear and tear, while also retaining their flexibility, case hardening is the ideal finish.

Case hardened steel creates a durable product that preserves the soft interior of the material to ensure that it remains shock absorbent. It also increases the wear resistance of the exterior of the metal, allowing it to last longer under more stressful conditions. If you want to increase the lifetime of your metals, this is the way to go.

Steel objects can be difficult to weld under some conditions. Case hardening ensures that it's much easier to weld. You'll end up with metal that's flexible but is tougher and strong than it was to begin with.

There are several ways to case harden your materials. Here are just a few of the most common.

Try Carburizing

When you put your metal through the process of carburizing, the surface becomes harder. Carbon is added to the component, and this fuses to it and creates a harder exterior.

The metal needs to be heated to 9000° C in order for this to work. It's then exposed to a carbon environment where the carbon then penetrates the metal to help and strengthen it. The carbon, in this case, can be a gas, liquid, or a solid.

While this is a costlier process than others, it's a powerful one.

With liquid carburizing, the depth of the hardness is a little bit volatile and the hardness may not be the same across the object. Having an object without uniform hardness is inappropriate for some applications.


When you go through this process, you need to be in a controlled environment for it to work. When you add oxygen to the process, the metal hardening process changes drastically. If you want things to be uniform, you'll struggle if oxygen is present in the process.

Some processes entail a partial vacuum, which helps by shortening the time it takes to harden the product. When the process is shortened, you'll save time and money in the production end of things.

Nitriding Is Powerful

If you'd prefer lower temperatures and to work with nitrogen, nitriding is a good way to get the job done. When case hardening your material via nitriding, heat your material up to 5500° C to get it ready to fuse with nitrogen. Once it's heated, expose it to the atomic nitrogen that will penetrate your steel or iron object.

Atomic nitrogen reacts to your metal, increasing hardness and resistance. This creates strong metal that's hard enough to withstand lots of abuse. The only thing to worry about is the fact that this process doesn't always work with every alloy of steel.

plasma nitriding

After you go through this process, you may need to do some serious grinding. This is an expensive process, because the thin white layer on the surface is hard to penetrate through.

Many fabricators prefer nitriding, despite this downside. It involves no more heat processes once it's fused. This means there's little chance that your object is going to get deformed with the heating and cooling process.

Cyaniding Works

If you're looking to fuse in a liquid bath, cyaniding is the way to go. This process introduces both nitrogen and carbon, in a bath that gives you the best of both hardening processes. When you dip your metal into this bath, you'll get a powerful hardened piece of metal.

The one major drawback of this process is that there are some serious environmental impacts to follow it. The creation and disposal of this cyanide bath are difficult to manage. Liquid carburizing baths are not available using special types of carbon instead of cyanide.

While you can get some thin depths with this process, you need to go through two processes before you're done. To achieve your desired result, expect to do some extra work when cyaniding.

Flame Hardening Is Powerful

If you want to harden your steel, you may be able to do it with just fire and water. Believe it or not, you can whittle the whole process down to just this and save yourself time, money and effort.

If you already have an oxyacetylene torch at hand, you'll be heating your hardened steel with this and bring it to a certain temperature. Once it hits that temperature, you'll quench the metal with water and let the magic happen.

In this method, hardening is more under control than any other process. You won't destroy your material as much, but there's a fair investment cost. Your product won't be finished until you go through some additional processes.

In this method, you can harden one portion of an object and leave the others alone. This can be helpful or it can be detrimental if you're struggling with a large or oddly shaped item.

Hire some skilled operators to help to ensure that you do it right.

Case Hardening Steel Gives You Nothing but Benefits

While there's a long process that's entailed in case hardening steel, there are endless benefits. If you want to ensure that your products last a long time, this is the process to go with. If you want the job done right, you should hire the largest Slovenian provider of heat treatment.

To see how we work, check out what's happening in our lab.

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