Spyderco byte September 2023 - EDGE-U-CATION®
EDGE-U-CATION® - The Advantages of Tool Steels
The topic of blade steels is a deep rabbit hole that is often overwhelming for the average knife user. While it might be possible to wrap your head around the qualities of the most commonly used cutlery steels, once you broaden your spectrum to include the full scope of specialty steels, you need to start doing your metallurgical homework.
Truth be told, Spyderco does not make this challenge any easier, as we have worked hard to become the industry leader in the use of exotic, high-performance steels in our knives. We currently offer 35 different blade steels in our standard product line. If you include discontinued products, Sprint Run™ knives, dealer and distributor Exclusives, and our groundbreaking Mule Team™ project, you can easily double that number. With those staggering figures in mind, we could say “We’re sorry,” but it’s probably more accurate to say “You’re welcome.” We take tremendous pride in the variety of blade steels we offer.
The Performance Balancing Act
The first step in understanding the complexities of blade steel is to evaluate them based on their performance characteristics. Typically, this is done with three primary qualities in mind: wear resistance, toughness, and corrosion resistance.
Metallurgically, wear resistance relates to a steel’s ability to withstand abrasion and impact without deforming. However, when it comes to knife blades, its meaning becomes more specific. Since the goal of a knife is to take and retain a sharp cutting edge, wear resistance translates more accurately as “edge retention.”
In evaluating the properties of blade steels, some people prefer to add a fourth quality: ease of sharpening. Generally, this quality is diametrically opposed to wear resistance and edge retention. Steels that hold an edge exceptionally well normally resist abrasion and are the most challenging to sharpen; however, that’s not always the case. Evaluating all four qualities helps highlight the exceptions to that rule.
With these criteria in mind, we have a basic platform to understand different types of steels.
Stainless Steels Versus Tool Steels
Stainless steels get their corrosion-resistant properties primarily from the addition of chromium. When chromium exists “in solution” in a steel, it promotes the formation of chromium oxide on the steel’s outer surface. It is this thin layer that protects the steel from corrosion.
However, when chromium combines with carbon, the result is the formation of chromium carbides. Although hard and wear resistant, chromium carbides are relatively large. They therefore weaken the structure of the steel and reduce its toughness. Chromium also tends to “steal” carbon away from other, more desirable, carbide-forming elements, like vanadium.
Knife enthusiasts often cite 13% chromium as the threshold for a steel to be considered stainless. In reality, the exact amount of chromium necessary for reliable corrosion resistance depends upon the steel’s carbon content and the presence of other contributing alloys. For the purposes of this article, however, our goal is to “go in the other direction.”
If we consider the three basic qualities of a knife steel—edge retention (aka, “wear resistance”), toughness, and corrosion resistance—corrosion resistance is arguably the most problematic. Adding a large volume of chromium to a steel generally undermines the other two qualities. As such, if we remove corrosion resistance from our list of desirable qualities—and make the commitment to maintain our knives diligently—we open the door to ultra-high performance in the other two categories. That’s exactly what advanced tool steels offer the knife enthusiast.
Cases in Point
Let’s say you’re an experienced knife user looking to broaden your horizons. So far, you’ve focused mostly on “mainstream” stainless steels that offer a balance of toughness, edge retention, and corrosion resistance. However, since you are disciplined enough to maintain your knives well, you’re ready to try some knife steels that offer levels of edge holding and toughness well beyond the scope of stainless steels. Spyderco has you covered.
In his excellent article “K390: Best High Wear Resistance Steel?” on knifesteelnerds.com, Dr. Larrin Thomas validates this concept by stating “The properties of K390 are quite excellent with ‘good’ toughness along with very high wear resistance and edge retention… The combination of toughness and wear resistance is unmatched by any available stainless steel.” Although his comment was specific to K390, in that same article, he also provides a chart rating 17 elite tool steels based on toughness, edge retention, and corrosion resistance. As you probably already know, Spyderco is the only knife company to offer K390 in a broad selection of regular-production models. As for the other 16 high-performance steels on Dr. Thomas’ chart, Spyderco has produced or is currently producing knives featuring 13 of them. Soon, that number will be increased to 14.
Like any other product, you can’t appreciate the difference until you’ve experienced the difference. The broad range of high-performance tool steels we offer in our products offers the perfect vehicle for that experience.