It’s Important to Know the Metal of Your Knife
Almost all knives will be made out of variations of two different steels: carbon and stainless. The crazy sequences of numbers and letters you sometimes see pinned to a knife are the steel grade, which vary depending on the mix of elements in the steel and the heat treatment. Most knife manufacturers are more than happy to provide detailed information on their steels on their websites, so this will just be a quick run down on the types of steel and various popular grades you can expect to see rather than an exhaustive explanation of how they’re made and everything little chemical that goes into them.
This is a simple combination of iron and carbon. You’ll see it in categories of low, medium, and high carbon steel (those categories also extend into stainless steel). Carbon usually makes up less than 2% of the steel. As a rule of thumb, the more carbon content the harder the steel, but this can still vary depending on combinations of other elements cooked into the metal.
Carbon Steel Grades
10xx – Runs from 0.45% to 0.95% carbon. The Last 2 numbers of the number indicate the carbon content. So for example, 1045 carbon steel is 0.45% carbon. You’ll most often see 1045 and 1095 used in survival knives. Esee and Ontario Knife Company are clearly big fans of 1095. Ka Bar uses something called 1095 CroVan, which has a little bit of chromium and vanadium (but not quite enough to make it stainless), in some of their bigger fixed blades in order to make them a little tougher.
Tool steel – Very high carbon content running up to 1.60%. Includes 52100, A2, D2, CPM. This isn’t the flashiest metal, but it’s incredibly hard and it holds an edge like a grudge.
Someone had the bright idea to add a bit of chromium to carbon steel and ended up with a knife that could be left out in the rain without showing rust spots a day later. This tends to be softer than plain carbon steel because of the way the various cocktail of other elements mix and react in the formula.
Stainless Steel Grades
400 series – The standard in stainless steel with carbon content running from 0.38% to 1.20%. Includes 420, 420HC, 440, 440C. You have a moderately soft steel at 420 levels, but with a good amount of corrosion resistance. This has made 420HC a favorite in Buck knives. They used to use 440 which is harder, but more difficult to maintain.
AUSX Series – A Japanese-made steel that adds a bit of vanadium to increase wear resistance and toughness. AUS8 is definitely the most common metal of the series used in knives, but you’ll see the occasional AUS6 (usually in old or cheaper knives) or AUS10 (usually on higher quality or kitchen knives).
SXXV Series – A very strong metal that’s great at resisting wear and holding an edge. However it is very difficult to sharpen so shaping and heat treatment are a lot more important. It’s a great premium steel, but only if its being made by someone who really knows what they’re doing. The most common you’ll see are S30V, S35V, S90V, and S110V.
Other Popular Steels
Some steels don’t belong specifically to a single category because they’re the result of innovative knife makers experimenting with various concoctions, so we’ve just compiled a few individual metals you’ll probably see floating around the knife-sphere.
154CM – A high steel mixed with vanadium that is very hard and fairly tough and holds an edge incredibly well. Many people equate it to ATS 34.
G2 – A low steel with an okay hardness. It’s also called GIN-1 steel, and is widely considered a mediocre metal. A nice way to make an affordable knife, but certainly not the highest quality out there.
420J2 – A very low steel with poor edge retention, but it’s incredibly tough and does not corrode easily. This has been falling to the wayside more and more with the increasing popularity of 420HC.
VG-10 – A very high stainless steel. It’s hard to beat in terms of hardness and edge retention, but it is a nightmare to sharpen. A lot of high grade kitchen cutlery is made with VG-10.
8cr13MoV – You could call this the budget Aus 8 steel. I general has around 0.8 carbon and a lot more chromium, so it’s not as tough and has around the same corrosion resistance with passable edge retention. However, it is a great way to make a knife cheaper, and doesn’t reduce overall quality too much so long as the heat treatment is good.
Thoughts on Choosing a Knife
If this topic doesn’t excite you, and you’re just sitting here overwhelmed by the barrage of numbers, letters, and carbon percentages, don’t worry. You don’t have to know the composition of a knife to know it’s good. Most companies are pretty resolute about using good steel, and if you’re paying over $20 it’s almost certain the steel is at least decent. But if you’re looking at a $5 dollar knife and wondering if it might still be useful, or looking at a $70 knife and wondering what’s weighing that price tag down, the steel is a good place to start looking.