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Blade steel is totally a super important factor to consider when buying a knife, but wait a second—it isn’t the be-all, end-all. Heat treat, blade geometry, the job at hand, and the sharpening of the blade all play a massive role in the performance of the steel.
Heat Treatment is the process of hardening and tempering the blade steel through heat. This increases the strength of the edge tremendously. A well-done and consistent heat treat goes a long way towards the performance of a knife. High hardness (60 HRC+) increases the edge retention of the steel at the cost of brittleness. Low hardness increases toughness at the cost of edge strength. The effect of heat treat varies based on the composition of the steel.
Blade geometry is a subject that deserves its own article, but here’s a summary. Cutting and slicing performance improves as the thickness behind the edge decreases. Additional considerations include the thickness of the blade stock and the primary grind. Knives such as the Spyderco Chaparral have a very thin edge at only .014”. In contrast, a thicker blade stock with more material at the edge will yield a tougher, less slicey knife like the Ka-Bar Becker BK2.
Sharpening goes hand in hand with blade geometry. A 30 degree inclusive edge means that each side of the blade is sharpened to 15 degrees. Inherently, more acute sharpening angles will see better cutting performance than more obtuse angles. In contrast, a more obtuse angle will be more stable and durable. Certain blade steels are more stable at highly acute angels.
Often overlooked is the job at hand. When you put your knife to work, what tasks will it need to conquer?
Knife steels that exhibit extreme hardness and edge retention are amazing at cutting through warehouses full of cardboard but hit a staple and your knife may suffer a chip. Tough steels excel at camp chores and batoning wood but are unable to be used at very thin edge profiles while maintaining edge stability.
In reality, there is no perfect blade steel in the same way that there is no perfect knife. Compare your use cases to choose the perfect knife for you.
The best blade steels exhibit a balance of strength and toughness. Blade steels with an insane amount of hardness (pushing towards 70 HRC) tend to lack stability and can suffer from cracks, chipping, and total failure. Extremely tough blades may not cut as well as desired and can suffer from edge rolling and difficulty maintaining an edge.
The charts below aid visualization of the strengths and weaknesses of a particular knife steel. The most well rounded steels like CPM-154 and 154CM create an even shape while a steel like CPM-3V is severe due to high toughness and lower scores in all other categories.
Bohler M390, CTS-204P, and CPM-20CV are all essentially the same steel and sport a near identical composition. With significant amounts of Chromium, Molybdenum, Vanadium, and Tungsten, these steels are 100% ready for action. CTS-204P is made by the USA-based Carpenter Technology Corporation and CPM-20CV is manufactured by Crucible Industries.
CPM-20CV can be found on my knives today and is made by the USA-based Crucible Industries. M390, 204P, and 20CV are all durable steels that sacrifice ease of sharpening.
Crucible Industries has a real gem on their hands with CPM-M4… At the cost of some corrosion resistance you get amazing edge holding, toughness, and decent enough sharpenability. Based on experience and testing, M4 steel may outperform blade steels such as M390 and S90V in terms of edge retention and M4 is in a completely different league in terms of toughness. Some people are uncomfortable carrying a knife that is susceptible to rust and corrosion, but keep your blade oiled and there won't be any problems.
CPM-S110V exhibits many of the same qualities as S90V. The primary difference is out-of-this-world edge retention at the cost of a minimal reduction in toughness. If you frequently use your knife to slice up cardboard, there may not be a better steel than CPM-S110V. Both of these steels are a real bear to sharpen up!
Bohler-Uddeholm produces more than just the famous M390 steel. Consider Elmax if toughness is high on your list. Excellent strength and toughness are balanced with very good sharpenability and corrosion resistance. Elmax is an amazingly well-rounded steel when you take all of these factors into consideration. Elmax can be found in many Microtech knives.
It may seem like there’s a big step down between a steel like S110V and CPM 154. Realistically, in normal day to day use you would struggle to pick out any differences in comparison. CPM-154 is an excellent EDC blade steel with above average edge retention, corrosion resistance, and ease of sharpening.
Both great steels, CPM-154 benefits from a powdered metallurgy and is finer grained than 154CM. Powdered steels are more consistent, have better edge retention, and improve toughness due to a lack of inclusions.
CPM-3V is, in many ways, the perfect blade steel for a fixed blade knife. Insanely tough, this steel also manages to boast excellent edge retention and corrosion resistance.
CPM-4V boosts the edge holding when compared against 3V, but at the cost of some slight toughness.