Steel and Knife Choice Simplified

You want to buy a new knife… A good knife. You’ve had enough of cheap knives that get dull quickly and never really get sharp in the first place. Maybe you have one that rusts when the weather report says “rain tomorrow” or the edge, more and more after every use, looks like grandma’s serrated bread knife and cuts just about as well. Yes you need a new knife but you have a problem. The descriptions of all the better knives describe the steel that is used but you don’t know which one is “best”. I am no expert on knife steel. I am going to tell you what I do know about it, and how I use that information to guide my choices when buying knives.

Often we find the options are among carbon, tool and stainless steels. There are others, but these are certainly the more popular categories. Simple high carbon steel will often be the lower cost option, it is generally easy to sharpen but will rust if not well cared for. Carbon tool steels may offer higher edge retention, through greater abrasion resistance, and even some degree of stain (rust) resistance. Both of these qualities are due to more sophisticated alloy compositions than their simple carbon steel cousins but they come with a higher price tag. Stainless steels generally offer higher resistance to rust, as the name suggests, but will often do so at additional cost over simple carbon steels. The same composition that is great for fending off corrosion may also yield a steel that has less resistance to abrasion or wear. This means you may find yourself sharpening a knife in this steel more often. All of these statements on the characteristics of the various types of steel are very broad. There are certainly steels in every category that will run contrary to them.

Strength and toughness too are qualities of all steels but are not as straightforward to understand as corrosion and abrasion resistance. In fact, they are related but also at odds with one another. Strength is the ability of the steel to resist a force. Toughness is a measure of the steel’s ability to resist these forces without failing. We see these forces in action against an edge all the time. When we hit a knot in a piece of wood we are splitting, the knife edge experiences compressive force. When we carve a notch in a stick to hold our pot over the fire, the edge is put to lateral forces. When the capabilities of a tough edge are exceeded it will deform, bend or roll, rather than fail outright by cracking or chipping. For a steel to be tough it has to have strength but in the right amount. Too much strength and it becomes brittle, too little and it will deform and roll easily. In both of these cases, strength diminishes toughness. Toughness is desirable because a tough edge can be realigned (bent back to true) rather than resharpened (removing material) to fix damage to the cutting edge.

To really complicate the blade steel choice discussion we can’t leave out hardness. Abrasion resistance and hardness are often thought to be the same thing. Both are at work making a blade keep an edge longer. While abrasion resistance, or the ability to resist wear, comes from the composition of the metal itself, hardness comes largely from the heat treatment of the blade.

We can examine knife design and choose characteristics most suited to our purpose be it bushcraft, hunting, EDC, kitchen or some other use. We can research a steel by name and select one based on its composition and associated characteristics of toughness, stain and wear resistance. We can weigh in the finished hardness from the knife maker. What we can’t easily do, is divine how the final blade is affected by the magic that is the knife maker’s heat treatment.

It is this process, the “special sauce” of the knife maker, that determines the final hardness and should put all of the characteristics of a given steel into balance making the knife perform optimally for its intended purpose. It is quite likely that a steel used by one knife maker could have somewhat different performance from the same steel used by another, due entirely to the heat treatment. Good heat treatment can make an average steel into a real performer and a great value. Poor heat treatment can make a high tech steel into something you wish you had not spent your money on.

I mentioned earlier, and it bears repeating, none of these statements about the characteristics of various steel types are absolutes and should serve only as guidelines. This said: Choosing a knife steel is usually about trade-offs. To get more of one quality you often have to give up some of another. Technology is ever advancing and many newer knife steels defy these trade-offs and offer the best of both worlds. Collectively they are known as “super steels”.

One group in this class of super steels, Crucible Particle Metallurgy or CPM, is named for the process used to make it. Rather than the traditional method of melting all of the components of a given steel and pouring that soup into ingots, CPM is a process used by Crucible Industries to make a uniform alloy steel at a molecular level by spraying that hot steel soup through a nozzle and cooling it quickly to form tiny spheres which together yield a powder. That powder is heated, nearly back to the melting point, and then pressed into ingots. Since the components that make up the alloy are very uniformly and finely distributed, we can have such things as a tough, stain resistant steel that hold a fine edge for a very long time. The physical characteristics may all be on the higher end, defying the compromises of non-super steels, but this time what we trade off for incredible performance is cost. Makers buy steel by the pound and the higher the tech the higher the price.

Now that we have covered many of the characteristics of different steels I’m going to tell you not to worry about the steel… to a point. I think that steel type is the least important variable you should consider when selecting a knife. There really is no “best” choice because if there were, everyone would be using the same steel. Blade profile (shape), grind, edge geometry and even comfortable handle design are more important than blade steel. Most important is to consider what you want to do with the knife. Ask yourself if the style you are considering is going to be good at that task. All of this assumes that you are looking at the knives of reputable makers, so you definitely want to do your homework in that area.

Once you have a good idea what you want the knife to do, and have chosen a style that is good at that task, only then should you begin to think about the steel used in the knives that make up your finalists. At the same time, it is likely you are looking at your budget and that will often narrow the field a bit more. At this point I think mostly about one thing: Will the knife be wet much of the time? If the answer for me is yes, then a stainless steel might be a good choice.

Is it good to know which steel is tougher, more wear resistant and less prone to rust? Sure. That information will fine tune your selections even more. In the end however, even with all of this knowledge, trust the knife maker. Odds are they’ve spent a good deal more time considering the knife steel choices than we ever will, experimented with the stuff to find out what works and what doesn’t, and they know the recipe to the secret heat treat sauce. Don’t skip over a knife because it isn’t made in the latest knife steel fashion, or even your tried and true choice of steel if you have one. Good makers spend a lot of time deciding what to make their tools from. Spend your time choosing a maker and let them do what they do best with the raw material.

 

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