Blade Steel Comparison for Knives
(Personal tests, updated 23 DEC 09)
On a scale of 1-10 with 10 being the best.
|Steel||RC Hardness||Edge Retention||Strength||Stain Resistance|
I determined the edge-holding qualities by cutting 3/8" diameter rope. To give you an example, the ATS-34 made 75 slicing cuts before not being able to cut all the way through, while the S30V made 155 cuts. For determining strength, the test blade was clamped in a vise with a protractor behind it and then was bent until it broke. ATS-34 went to 45 deg. and S30V @ 58.5 Rc bent to 75 deg..
Because of the testing I've done, I now make knives primarily out of S30V, but I also still use ATS-34 upon request and because it is so popular.
A good source of blade steel bar stock is Admiral Steel & Jantz Knifemaking Supply
ATS-34 is a good choice and has been the hottest high-end stainless in the 1990s. 154CM is the original American version, but for a long time was not manufactured in the sizes knifemakers need, and then not at all, so knifemakers switched over to ATS-34. The Crucible Company is again making high-quality 154CM, and some companies seeking to stick with American-made products are using it. ATS-34 is a Hitachi product that is very, very similar to 154CM. Normally hardened to around 59-61 Rc, it holds an edge very well and is tough enough even at that high hardness. Many custom makers and production companies use ATS-34.
BG-42 is somewhat similar to ATS-34, with some major differences: It has more manganese and molybdenum than ATS-34, and has 1.2% vanadium (ATS-34 has no vanadium), so look for better edge-holding with that vanadium than ATS-34. BG-42 is usually hardened to 61-63 Rc.
440C is an excellent, high-end stainless steel, usually hardened to around 56-59 Rc, very tough and with good edge-holding at that hardness. 440C is generally considered a very good general-use stainless, tougher and more stain resistant than ATS-34 but with less edge-holding. I keep the hardness down to a maximum of 59 Rockwell C scale. Any harder than that I have experienced a fine gray line of edge chips when attempting to put the final edge on it. It makes excellent fillet knives at 56 Rc that will take 90 degree bends on 10" blades. Also makes very good kitchen cutlery at 56 Rc.
S30V has been designed for knife blades. It's alloys have been chemically blended to bring out the best qualities of edge holding, toughness and, stain resistance. Manufactured in the USA, it is made from powdered alloys sprayed into a canister and heated to bonding temperature. The resulting billet is then roll-forged by conventional mills into sheets and bars. Edge holding is incredible. I normally have Paul Bos Heat Treating temper the finished blade to 58.5 Rc, but it can be tempered harder to 60 Rc and still not be overly brittle. It is the vanadium carbide formed during tempering, not the hardness of the steel that causes it's great edge holding ability. Using a Norton brand "Fine grit India Oilstone" I personally find S30V not difficult to sharpen.
STEEL: ALLOY %
ALLOYING ELEMENTS IN STEELS
CARBON (C) increases edge retention, raises tensile strength, increases hardness and improves resistance to wear and abrasion.
CHROMIUM (Cr) increases hardness, tensile strength and toughness. Provides resistance to wear and corrosion.
COBALT (Co) increases strength and hardness and permits quenching in higher temperatures.
MANGANESE (Mn) increases hardenability, wear resistance and tensile strength.
MOLYBDENUM (Mo) increases strength, hardness, hardenability and toughness.
NICKEL (Ni) adds strength, hardness and corrosion resistance.
PHOSPHORUS (P) improves strength, machinability and hardiness. Creates brittleness in high quantities.
SILICON (Si) increases yield strength, tensile strength and de-oxidizes and de-gasifies to remove oxygen from molten metal.
SULFUR (S) improves machinability when used in minute quantities.
TUNGSTEN (W) adds strength, toughness and hardness.
VANADIUM (V) increases strength, forms carbides for edge holding and resistance to shock impact.