This may be of some interest to some of you all.It is a e-mail that I replied to and thought I would pass it on------
Matt, knife hardness is usually referred to in the Rockwell "C" scale" in the USA. General kitchen cutlery is usually in the lower to mid 50's on the C scale. Each steel has a maximum hardness level and a recommended working hardness. When a steel is heat treated it can be hardened to any level between the minimum and maximum level. for example ATS-34 hardness range 22 RC to 63 RC. 22 being dead soft and 63 being maximum obtainable hardness. Most good ATS-34 knives will be in the 59 to 61 range. There are exceptions such as if a blade is to be subjected to hard use and abuse the hardness should be lowered to increase the toughness, conversely if the knife is to be used as a cutting blade with little or no abuse it could be made harder to increase the edge holding ability. I am sure there are sites you can go to get hardness info on the various steels but I am not aware of them. Most steel companies will provide customers with data sheets of the steel they produce. They are free for the asking. Most knife makers should have these data sheets for the steel they use. I know I do. I am no metallurgist but I will try to answer any question you have on a specific problem. Regards Rade
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Good thread, Rade! I know that virtually all heat treating is in the nature of a compromise- toughness, edge holding, rust resistance, etc., so you have to have a pretty good idea of what the main use of the knife that you are making will be before it is heat treated.

In my case, I often sacrifice a point or two of hardness on ATS34 by tempering at 400 deg. instead of 900 deg., but this gives me greatly increased corrosion resistance. I wind up with a tougher, more stain-resistant blade, but at a hardness of 58-59 (which, by the way, is a lot easier to sharpen than 61 Rc).