Here's what I've learned about tempering and heat treating metals. Each steel type has a tempering, heat treating and quenching method that is unique to that family of steel and at a certain temperature and duration as far as tempering / quenching goes that allows that particular steel type to reach a hardness level measured by the rockwell C scale. So I don't believe that one metal rated at 58 RC means it's any better than one that has been tempered and treated to 56 RC. This process or formual being different to each steel type allows the metal to reach a usable state of hardness with out becoming to brittle. A good explaination of this is in Wayne Goddard's "$50 Knife Shop" book. ISBN 0-87341-993-6 for $19.95. There are numerous other books and web sites that explain this much better than me.
Here's some web links for additional information.
The best I've found of what type of steel to be used for knives is by the late "Bob Engnanth" at this URL http://www.ameritech.net/users/knives/steels.htm
Mr Enganth words on 440C is Quote "440C was the first generally accepted knife makers' stainless and remains quite popular, particularly since the sub-zero process was developed to add toughness. On the grinder, it's gummy and gets hot fast,
but it cuts a lot faster and easier than any of the carbon steels. Your belts will cut about 2 to 3 times as much 440-C than 0-1. Using hand hacksaws on it will wear out a lot of blades in a hurry. But with the proper care, good heat treating and finishing,
440C produces an excellent, serviceable and durable knife, even for the new knife maker. Anneals at very low temperature. Please note that 440A
and 440B are similar alloys, often confused with 440C, but not worth a damn for knife making use. Commercial knife companies often mark blades 440 when they're one of the less desirable versions, giving the real stuff a bad name. 440C is also
available in more sizes and in more places than just about any stainless alloy suitable for knives. It is also essential to remember that collectors hate to see
one of their prizes turn brown in the sheath, and 440C handles corrosion resistance very well. While the variation, 440-V doesn't seem to get quite as hard, but holds an edge for much longer and is much more difficult to grind."
Mr Enganth words on a couple of high carbon steels Quote " 5160 is a common spring steel, basically 1060 with one per-cent of chromium added to make it deep
hardening. (It may still be selectively drawn with a softer back, if desired.) An excellent steel for swords, or any other blade that will have to take some battering. The choice of Jim Hrisoulas who makes some of the finest working swords in the business. Long blades are best around the mid 50's on the Rockwell scale, while small, working blades can be put into service at a full 60 RC. Forged blades with a well
packed edge seem to cut forever! Rough on grinding belts. Jokingly called O-C-S, old chevy spring.
52100 is a ball bearing steel, generally not found in useful grinding sizes, but terrific in edge holding and toughness. 52100 is 5160 with an attitude, more alloy and more carbon that makes it harder and tougher. Like 5160, throws a brilliant yellow spark. Ed Fowler has developed a superior heat treating technique for this steel." End Quotes.
I've worked with most of the knife metals in the field available now and totally agree with the above words. High Carbon is the way to go and 52-100 is by far the best knife metal I've ever ran across. It needs some extra maintance but is well worth it in the field elimnating the need to constantly be sharping your knife. Marbles Knives are the only mass knife production company I know of using 52-100 and are damn cheap compared to the $500.00 custom you talked about. I've taken a expert II model and chop a 2x4 clear through then shaved hair from my arm. Bad ass metal...
Be cheap, easy, and hard to offend!|