There are a lot of different types of steels that go into making knife blades. Common carbon steel like 1095 (essentially iron alloyed with 0.95% carbon) or spring steel like 5160 which sometimes referred to as OCS for “old Chevy spring” although vehicle leaf springs these days are unlikely to be 5160. On the other end they could be cheap, stamped stainless like Krupp 4116, which is about as useless a blade steel as I’ve ever come across in terms of edge retention, or something that is a bear to sharpen but holds an edge like 420J2, 440C, ATS-34 or 154CM.
So…what steels are worth it versus which are just marketing? You can make a great blade out of nearly any steel, but the ones I like are 1095, 5160, O1, D2, and 440C. I have blades made from S7 and 52100, but honestly the additional cost that generally comes with them makes them kind of uncommon choices for most people, along with A8. All of these can make a fine blade, so here are my thoughts, for anyone considering making their own knife or purchasing one.
Here are the steels that you can treat at home with a firebrick forge and an oil quench.
1095. This steel will be with us for about forever as a blade steel. It is easy to work with in terms of forging, grinding, and heat treating. It can be phosphate treated like a milspec knife, or mirror polished. Rusts if you don’t care for it, lasts a dang long time if you do. Can be brittle if not properly tempered, but cheap to buy as stock. Everyone should have a 1095 knife at some point in their life.
5160. I like this steel for anything that is going to be more “chopper” than “slicer.” Holds an edge well when properly heat treated, and has slightly better impact resistance over 1095.
O1. This is the original “oil quench, non shrinking” tool steel. I think it is about as easy to work with as 1095 or 5160 with slightly better edge retention for a given Rockwell hardness on final temper. That is just my opinion, and your experience may vary.
52100. This is an industrial bearing steel that has pretty complicated heat treatment tables. Makes a fine knife, but isn’t easy to work with, which is why so many 52100 knives cost so much, but don’t really perform any better than a cheaper 1095 or D2 blade of the same design and geometry.
Here are the steels where you really need a digitally controlled furnace to properly heat treat the steel.
D2. This steel is pretty famous for wear resistance as a die making tool, also surprisingly tough, relatively corrosion resistant due to the chromium content. This steel will hold an edge very well with proper edge geometry for the blade style and when tempered to a reasonable degree for the chore intended. Not a great option for salt water use.
420 and 440 family of steels. These steels get a bad reputation because they are hard to do right. Buck has used 440 and 420 for years, and while I’m not a huge fan of the blade geometry on most Buck brand knives, they do produce a consistent product that holds an edge well. If you have a digital controlled furnace to heat treat these steels, you should be fine, but if not you can send any blade you grind from stock out for heat treatment at a commercial outfit. These are a better choice for use around salt water, but you’ll still want to care for the blade with a good protective oil. These are great options for pocket knives.
ATS-34 and 154CM. These steels are slightly more brittle than 440 series, but hold an edge amazingly well. Can be a beast to sharpen without a diamond stone. If you are around salt water a lot, this steel is a great option. These are great options for folding pocket knives.
The truth about a blade is that a proper heat treat for the blade design, sharpened to a proper edge geometry, will make any decent steel perform well. This isn’t even getting into laminate steel blade designs (a hard core between two softer pieces) or pattern welded “Damascus” steels. Right now I think that there are a lot of really good options for someone who wants to purchase a blade made from almost any steel mentioned here, especially D2 and 1095 options as a lot of domestic makers and importers are using those alloys.
I will say that I’m not a fan of Krupp 4116 steel, it is a stainless steel designed to make stamped blades. If you just want a “throwaway” knife to stash somewhere, this might be a legit use for a cheap “Cold Steel Finn Bear” or other option made from this alloy, but honestly for the price a Morakniv is just as affordable and the Swede stainless steel seems to hold an edge better.
If I didn’t cover an alloy you are interested in, hit me up in comments.