Lately whether by fashion or by merit, carbidized edges have become a popular performance add on for many knifemakers. Though I still get asked the question… What is carbidizing?
Carbidizing is the process of micro layering Tungsten Carbide onto a metal surface. Tungsten Carbide is very hard, typically much harder than the steel its being applied to, and thus offers a lot more wear resistance to the metal. This method was first used by knifemakers who were creating folding knives with Titanium parts in the locking and folding mechanisms. The layer of Tungsten Carbide effectively prolonged the life of the working parts inside the knife.
The process has spread however to another area of knifemaking, that of Carbidizing the edge of a knife.
Typically, this is done on knives made of Titanium, which is in itself not an ideal metal to hold a cutting edge for very long. Though there are various ways of improving the edge holding ability of certain grades of Titanium, carbidizing is a very quick and relatively easy way of doing it.
It works optimally if adding the layer of Tungsten Carbide to a single side of the edge. As the knife is used, and the edge begins to wear, the softer metal is worn away and exposes more of the much harder Tungsten Carbide. Thus, in effect, it creates a self-sharpening edge – that is the theory.
In practice, you could theoretically carbidize any metal or steel that is softer than the Tungsten Carbide, which resides at somewhere around 70 Rockwell. A carbon steel blade at 60 rockwell is therefore viable to Carbidize.
Does it help to carbidize a carbon or stainless-steel blade? Well that is very much debateable and for some the jury is still out. Whether this gives any real practical advantage is yet to be determined. However, I can share that from my experience it does alter the cutting edge.
This is especially prevalent on Asymmetric edges (or chisel grinds), where adding a carbide layer seems to produce a very sharp but ultimately jagged cutting edge which tends more to rip than slice. Now, depending on the goal, this can be a good or a bad thing. It ultimately depends on what purpose your knife is for.
When it comes to the art of creating purposeful and practical self defense edged weapons, I like to take the position that penetration is more valuable than the ability to cleanly slice. So whether the edge cuts finely or has a jagged cut is rather immaterial to me personally.
I offer carbidizing as an option, and as a part of the design aesthetic on models like the Sin Eater. In testing, it cuts – and that’s all that really matters. I haven’t yet been able to determine whether it keeps the edge sharper for longer on my carbon steel blades, however it would be almost a requirement for any Titanium blade.