Knife Steel – Edgy Stuff

In fiction and movies we have the luxury of knowing the value and quality of a metal by virtue of a cool name and a backstory. There's adamant, adamantite, adamantium, adamantine, duranium, Nth metal, galvorn, the Rearden Metal, transformium, and of course one of the very first to impress — mithril.

In real life, however, it's not so easy to discern what metal is best for what knife or tool purpose. That's largely because every intended use demands its own specific alloy. For instance, some implements must be extraordinarily sharp, but are not required to withstand abuse; others will be used in environments where corrosion is a threat to tool longevity.

Knife steel is generally categorized in five categories; hardness, toughness, wear resistance, corrosion resistance, and edge retention. There are different kinds of steels, each with varying abilities to meet those five “qualifications”. The most common (for the lay user, anyway) are tool steel, carbon steel, and stainless steel. Each has relative strengths and weaknesses in comparison to the others.

OFFGRIDweb recently ran a piece on this very topic, citing an excellent article from Pocket Knife Today. You can read that right here to learn more.

Another term frequently used when talking knives and tools is Rockwell Harness. The Rockwell Hardness Scale is used to describe not the composition of the knife steel, but, well, its hardness, using the formula “HRC” — which isn't to say composition is not important. It is, though perhaps not as important (relatively speaking) as the heat treatment of a blade. Generally speaking, a higher number indicates a greater hardness, but a lower toughness. It will result in superior edge retention to a lower number, but will be more likely to suffer damage or even fail under abuse. A lower number will indicate less edge retention, but a greater ability to withstand punishment.

The optimal HRC number then is somewhere in the middle, and will vary depending upon the intended use. In simplest terms, a surgeon's scalpel requires a different HRC rating than a lumberjack's saw.

For more information, and to check out Knife Art's comparison of steels ranging from 420 to ZDP-189 (sorry, no adamantium), go read this article right here. Be sure to also check out this knife steel composition chart.