Choosing a knife can be daunting. Between the brands, models, and options there are thousands of options for the average consumer to consider. One of the most important things to consider in your new knife is what the blade is made out of. The blade steel can tell you whether the edge is durable and soft, sharp and hard, or somewhere in between. This is a very brief crash course about blade steels in order to help you chose which one is best for you.
Before getting into specifics, it will be important to know why you should care about blade steels, and why blade steel is related to choosing your next blade.
Why You Should Care. (A Basic Understanding)
Randomly select 5 blades on the commercial market, and chances are they will all serve a different purpose. Most consumers don’t care about purpose. Most people think:
A knife is a knife. It cuts things, so it’s a knife. It’ll do.
The fact that you are here reading this article means that you don’t believe in that philosophy, or you just don’t know better and want to learn more about what blade steel is right for you. Either way, it’s a step in the right direction. Blades all have their own purpose, and you should choose your blade, and your blade’s steel, based on your intended use.
Think about it this way. You’ve got a fresh loaf of sourdough bread on the counter, what are you going to slice it with?
A bread knife!
It seems like a no brainer, right? That’s because a bread knife has been specially designed to cut bread. Sounds obvious because it’s called a ‘bread knife,’ but let’s actually think about what that means. This tool has been purposefully made with serrations in order to rip through hardened bread surfaces. It is made out of stainless steel to provide longevity to the average consumer. It is usually 8-12 inches long in order to span the width of a loaf of bread. If you had a choice to cut bread with a bread knife or a butter knife, you’re going to pick the bread knife because it performs the task best. Now, apply that same theory to blade steels. Sure, a lot of them look the same, and sure they all cut something, but that doesn’t mean that all blade steels are the same. They all have a purpose. They all have their own ‘loaf of bread.’
The most basic understanding of buying a new knife is understanding what you will be using it for. Ask yourself two questions to begin with:
- Which will the knife encounter more, impacts or precision slicing?
- Will it be used mainly indoors, or out of doors?
These are simple to answer, but they can greatly help you with finding your ideal blade steel. Generally, we will be focusing on outdoor blade steels in this article, because there is much more variety and confusion among them.
Why Blade Steel is Related.
So there are a hundred different things we could discuss when it comes to the makings of a good blade steel, but this article is more designed to help with the why and what than with the how. So why does a blade steel matter? Because blade steels are either extremely durable (soft and tough), extremely hard (brittle and sharp), or compromising somewhere in between the two. If you want a blade that keeps its edge for long periods of time, it will need to be hard and brittle. If you want a blade that won’t flex or break, it will need to be tough and ‘softer.’ Unfortunately, due to the properties of steel alloys, you can’t have the two extremes in one blade because they tend to counter one another. You give some toughness to take some hardness and vice versa.
So, with that in reason, everybody decides that they want the perfect in-between blade. The 50/50 that won’t break or lose an edge. The “perfect medium” blade steel. There are many ways that blade steel compositions are approaching this ideal middle-ground, but the processes involved can make a blade quite expensive and/or rare. The fact of the matter is that man has been playing around with steel for thousands of years, and we’ve gotten our processes down pretty good. We’re comfortable with steel, and we’ve made a lot of different varieties that work in a variety of situations. Today, most blade steels will be quality, so you just have to pick the right one for your loaf of bread.
Most durable and popular knives available today are made from one of the common blade steel composites that we will be addressing in a moment. These common steels are what most knives on the market are made out of, and so they are what we’ll be focusing on here.
Basics to Finding a Blade Steel.
Let’s get a bit more technical. When you go looking for a new shiny blade there are a lot of properties to consider. Generally, you should be looking for these properties:
- Edge Retention – How well the blade can keep its sharp edge.
- Corrosion Resistance – Blades are metal, and metal can rust. This is the degree to which the steel can resist oxidation.
- Hardness – Mentioned earlier, this is how much the blade will resist changing its shape.
- Toughness – Mentioned earlier, it is how much impact the blade can absorb before cracking, snapping, or chipping.
- Wear Resistance – The ability of the blade to resist wear and abrasions from excessive use.
Unfortunately, blade makers do not have a rating system to grade these properties. In fact, most blade makers will just tell you every one of their knives excels in all of these properties. This is where the “a knife is a knife” mantra comes from. People see there are different blade steels but don’t care about the differences since the advertising says it will cut anything, anywhere. Time to wise up!
Basically, steel is just iron, with carbon added. The more carbon added to the iron, the harder the steel will be. But keep in mind, the harder the steel is, the less tough it is. In reading those last three sentences, you have just become more aware of blade steels than 90% of consumers. You now have the ability to look at a steel’s alloy composition chart and determine how hard and/or tough it is. So, if S30V steel is 1.45% carbon, and AUS-8 steel is 0.75% carbon, what is your conclusion? S30V is harder, while AUS-8 is tougher. Gold star!
So what else in the alloy composition should we look for to give away its properties? Now we’re getting into it…
- Chromium – This is what makes the steel corrosion-resistant. The higher the percentage, the more it will resist rust. However, it also increases hardness. 13% Chromium or higher is considered “Stainless Steel.”
- Cobalt – Adds additional hardness.
- Manganese – Makes the steel harder, and improves wear resistance.
- Molybdenum – Makes the steel harder, especially noticeable at higher temperatures.
- Nickel – Makes harder steel, tougher steel, and adds corrosion resistance.
- Nitrogen – Adds hardness similarly to carbon, but is more corrosion resistant.
- Phosphorus – Makes a very hard and brittle steel.
- Silicon – Makes a harder steel.
- Sulfur – Like phosphorus, it makes a very hard and brittle steel.
- Tungsten – Increases wear resistance.
- Vanadium – Increases wear resistance and makes the blade easier to sharpen.
So, now it is time to apply your knowledge. You can now look at a chart of common blade steels, and determine which one suits your needs best. For practice, here is a chart of some of the most popular blade steels used in manufacturing today. Keep in mind, these percentages are close estimates, but the actual compositions may vary between steelmakers.
At this point, you might start to get lost again. You might be wondering:
Ok, I know what the chart means now, but I still don’t have any frame of reference. I know which ones are harder and which ones are tougher, but I still don’t know which one is right for me.
Finding your perfect blade steel will be a discovery process. Since each individual uses their blade differently, how a blade steel performs for you specifically will vary. The chart above contains a fairly well-rounded group of common steels, so it would be safe to theoretically apply these percentages globally. For example, D2 and S30V would be considered “high-carbon” (and very hard) in the steel world, even without comparing it to every other steel compositions omitted from the chart.
Finding your ideal blade steel should be an interactive process, so don’t just assume you know how a new steel will behave by looking at its components. The component charts are just a start. To really find your perfect blade steel, you are going to have to get your hands dirty. Buy a few that look good on the chart, use them, sharpen them, and take notice of how they age and perform.