Generally speaking, up until recently there were only two options when it came to knife steels: high carbon and stainless steel. This made choosing a knife steel straightforward and simple. Nowadays there is a lot more nuance involved. Thanks to people like Dr. Larrin Thomas, we have a much greater understanding of knife steel. Specifically, performance metrics, heat treat methods, and steel microstructure. One surprising downside of Dr. Thomas’ research is that instead of clearing up the waters, they become muddier. This is not to say that his research is poor or unhelpful, it means quite the opposite. The more we learn about knife steel, the more we realize how little we actually know. In addition to Dr. Thomas research, there has been a large uptick in cutlery steel research and development in recent years. We currently have more knife steel options and information that we know what to do with. Instead of simplifying and streamlining the knife (steel) buying process, we have complicated it tenfold.

Dr. Thomas research is freely available to anyone with an internet connection. The abundance of information has created a culture in the knife world known as “steel snobbery”. Steel snobbery is akin to armchair quarterbacking, meaning everybody is now an expert on the subject… or at least they think they are. This snobbery has created the narrative that “old” steels are no good and that maximum hardness is the most important factor in whether or not a knife steel is good. This belief is false and has turned people off of a lot of quality knife steels.

I hope to provide a deeper understanding of knife steels and a bit of a framework, or guide, on how to choose the proper steel for your next knife purchase.

If you want to jump ahead to the steel charts and my recommendations click here or here.

I don’t know where to start so I’m going to jump right in and see where my thoughts take me. In the interest of simplifying this topic, I will be leaving bits and pieces of information out. I am only going to cover the topics that I find most important. If after reading this article, you want to dive deeper into the world of knife steel, I recommend picking up a copy of Knife Engineering by Dr. Larrin Thomas.

In my opinion there are three factors that need to be considered when you are choosing a knife steel: toughness, edge retention, and corrosion resistance. Toughness is best described as the steel’s resistance to chipped edges and broken blades; edge retention is essentially how long the knife will cut before going dull, and corrosion resistance is how resistant the steel is to staining and rusting. All three of these factors are controlled, in large part, by the hardness of the steel.

Cutlery steel can be broken into three categories: low alloy (high carbon), high alloy (non-stainless), and stainless steel. Low alloy steels are known for their keen edges, ease of sharpening, and lack of corrosion resistance. High alloy steels tend to have better corrosion resistance and edge retention than low alloy steels. Stainless steels are best known for their resistance to corrosion.

Like anything in life, there is no such thing as the “perfect” steel. Choosing the best steel for you involves a a series of trade-offs or sacrifices. The three factors mentioned above, as well as the hardness of the steel, influence each other. For example if you want a steel with extreme toughness, you are generally sacrificing some amount of edge retention and hardness.

Generally speaking, the relationship between each of these factors (including hardness) is as follows:

• High toughness = Less edge retention
• High toughness = Less corrosion resistance
• High toughness = Lower hardness

• High edge retention = Lower toughness
• High edge retention = Less corrosion resistance
• High edge retention = Higher hardness

• High corrosion resistance = Lower toughness
• High corrosion resistance = Less edge retention
• High corrosion resistance = Higher hardness (in stainless steels)

• High hardness = Lower toughness
• High hardness = Greater edge retention

It should be noted that the list above is very generalized and that there are exceptions to most if not all of the rules. The list covers the entire spectrum of knife steels, from low alloy all the way to stainless. If you look at each steel category independently you will find that there is a lot of nuance and that the rules don’t always hold true. Defining these differences would really drag us into the weeds, and they won’t matter much to the average user so we’ll just ignore them for now.

In my opinion steel selection is very purpose driven. Using the wrong steel for the job could result in premature failure of the knife. For example, choosing a high carbon steel to use on an offshore fishing boat would result in major corrosion and pitting of the knife steel. A stainless steel would be the ideal selection.

Low alloy carbon steels are the oldest, and historically, the most widely used knife steels. They have been used successfully in every corner of the Earth. From arid deserts to salt sprayed beaches, carbon steels have stood the test of time. Low alloy steels are very susceptible to corrosion and rust. Because of this, low alloy carbon steels require more care and maintenance than stainless steels. Low alloy steels often have poor to fair edge retention. This isn’t to say that carbon steels make bad knives, that couldn’t be farther from the truth. What carbon steels lack in edge holding, they make up for in edge keenness and ease of sharpening. Carbon steels are incredibly easy to sharpen and they take a very fine edge.

Low alloy carbon steels are extremely popular in bushcraft knives, and are often used in hunting and kitchen knives.

High alloy steels often fall into the categories of “tool and high-speed steels”. Simply put, this means that many steels were originally developed for use in industry and manufacturing. Manufacturers needed steels with high wear resistance and toughness for manufacturing processes. Many high alloy steels originated as dies, drill bits, and industrial saw blades. It was later on that people discovered these steels were suitable for knife blades. High alloy steels make great knives, they are generally high in wear resistance ( or have good edge holding), moderately corrosion resistant, and very tough.

These steels are commonly used in bushcraft knives, “survival” knives, large chopping knives, as well as EDC knives and recently they are finding use in pocket knives.

Stainless steels have become the center of attention in recent years and for good reason. They have seen the most innovation and break throughs in the last 20 years. Prior to the rise in popularity of knives ( specifically custom knives) there were very few stainless steel options available. For decades you had “surgical stainless steel” and a few varieties of 440 stainless. These steels performed poorly when compared to carbon steels, but were popular due to their corrosion resistant nature. Fortunately, this isn’t the case anymore. Stainless steels are very intriguing because they are often equally as tough as low carbon steels, and have better edge retention. They also stack up fairly well against high alloy carbon steels. This is the very reason stainless steels are so popular, they are very well balanced, and there are a lot to choose from.

Stainless steels are popular in kitchen knives, bushcraft knives, edc knives and pocket knives.

Low Alloy Steel

High Alloy Steel

Stainless Steel

Above are three tables showing the toughness, edge retention, and corrosion resistance of common low alloy, high alloy, and stainless steels. These tables, prepared by Dr. Larrin Thomas are an invaluable tool when trying to find a steel that is properly balanced for your intended use. Keep in mind that an edge retention score of 1.5, while poor compared to other steels, is not bad. A steel with 1.5 edge retention is still better than almost any cutting implement from any time in history. In fact, 1095 may be the most popular knife steel of all time, and is still currently the preferred steel of manufacturers like Becker Knife and Tool and ESEE.

Before we dive into selecting the proper steel for your next knife, one thing needs to be taken into consideration. Sharpening. Sharpening is the bane of most knife users existence. If I had a nickel for every time I have heard the phrase “that knife is junk, it is impossible to get sharp” I would be sitting on an island and not at my desk writing this article. 9 times out of 10, a knife’s inability to “get sharp” is due to the failure of the one doing the sharpening, not the steel itself. The truth is, most people don’t know how to sharpen their knives and they usually don’t have the proper equipment for the job. If you are trying to sharpen a modern stainless steel on grandpa’s old stone, you are going to be very dissatisfied. Stainless steels have carbides in their microstructure. These carbides are hard and don’t respond well to “old school” sharpening stones. They prefer diamond stones. Diamond stones can be quite expensive and cost prohibitive to some. That being said, low alloy carbon steels love “old school” stones. In fact, I still sharpen many of my low alloy blades on my grandpa’s old Carborundum stone.

This is why sharpening needs to be factored in when choosing a knife steel. If you are already set up with diamond stones, you will be able to sharpen anything. If you don’t have diamond stones and aren’t ready to invest in them, I recommend sticking with low alloy steels or with steels below an edge retention rating of 4 on the charts above.

Choosing a knife steel is like choosing what flavor ice cream to order. There are a ton of flavors, all are good, but we all have a favorite. There are a few basic notes that need to be discussed so we have a framework to work from. If you live in a coastal area or an area with high humidity a steel with moderate corrosion resistance is ideal. I would suggest something with a rating of 7 or above. If you hate sharpening then a higher edge retention steel is what you are looking for, but keep in mind it will be more difficult to sharpen. If you want a bomb-proof survival knife I recommend a steel with a toughness of 7.5 or higher.

If the charts above don’t make a ton of sense to you, here are a few of my recommendations:

Low Alloy:

• 8670: extremely high toughness, ease of sharpening, low edge retention, keen edge
• 80CRV2: extremely high toughness, ease of sharpening, low edge retention, keen edge
• O1: moderate toughness, ease of sharpening, low edge retention, very keen edge

High Alloy:

• A2: moderate toughness, ease of sharpening, moderate edge retention, moderate corrosion resistance
• CPM CruWear: high toughness, moderate sharpening, good – very good edge retention, moderate corrosion resistance

Stainless Steel:

• AEBL: high toughness, ease of sharpening, moderate edge retention, good corrosion resistance
• CPM S35VN: moderate toughness, moderate sharpening, good edge retention, very good corrosion resistance
• CPM MagnaCut: high toughness, moderate sharpening, great edge retention, great corrosion resistance

At the end of the day, choosing the proper steel for the job is more important than the steel itself. A properly balanced steel is crucial when you are looking to purchase a tool you can depend on when times get tough. Too many people get caught up in the type of steel and it’s hardness but forget that knives are tools and tools need to be able to hold up to the job at hand.

References:

• Thomas, Larrin. Knife Engineering: Steel, Heat Treating, and Geometry. Independently Published, 2020.
  
• Thomas, Larrin. “Knife Steels Rated by a Metallurgist – Toughness, Edge Retention, and Corrosion Resistance.” Knife Steel Nerds, 10 Apr. 2023, knifesteelnerds.com/2021/10/19/knife-steels-rated-by-a-metallurgist-toughness-edge-retention-and-corrosion-resistance/.