Blade Steel Comparisons - Initial Report

[Cobalt]

Didn't mean to sound, well, mean. Sorry, just felt attacked when HoB called my info meaningless and then you kind of agreed. So I found my sources on where I got my info from.

No problem. I think your info is spot on for the most part, but there is variation. For example, speaking of something I know about, which isn't much. Busse's INFI steel is currently running at an Rc of 58 or so. In the 99-2001 period the number was nearly 60 and the first run of INFI was at 62 with some specimens at an Rc of 65, this is all from a steel with 0.5% carbon. At an Rc of 62, it was plenty tough and cut great. My guess was that the Rc was dropped due to the extreme use of the knives, at the expense of edge holding I would guess. However, the huge range from 58 to 65 Rc is not perfect at any one point but it will work at several points.

 

[knarfeng]

Is it just me? A 58 to 61 RC point difference/range seems like alot even on knives with the Byrds price point.

Maybe, maybe not. Each heat lot of steel will have a slightly different composition. Even with exactly the same temp profile hardness will vary with the specific elemental composition of each heat lot. But that brings up another variable: the uniformity of the oven temp. I've run temp profiles on ovens before and they all need considerable tweaking to reach uniformity. If the oven is not uniform blades that sit in a hot spot, or in a spot that reaches temp faster than the control thermocouple are likely to turn out a bit softer. Blades that don't see full temp or full time at temp are likely to turn out harder.

Shucks, I'm happy with any of my blades if they measure out at 58 or more. At the Byrd price point I think 58-61 is a fair enough hardness range.

 

[HoB]

Sorry, just felt attacked when HoB called my info meaningless and then you kind of agreed. So I found my sources on where I got my info from.

It was not my intention to attack you and neither is your information meaningless, but it was incomplete to the point were it was not really useful. It is a common misconception among those that don't really have thought about it much, that hardness is a property of the steel. That is not true. Hardness depends both on steel and heattreat. Certain steels can not be hardened as high as others and and for others again only a certain hardness range is sensible. But then again there are some big debates about how hard to run certain steels, like S30V for example. You see that Vivi did not ask for the hardness of certain steels but for the hardness of the steel in very specific models from very specific companies. This was not a question about your source in the sense that we don't believe your numbers, but rather a question for the missing piece of information as to who's steel xxx is hardened at yyy Rc.

Just to give on specific example. The general hardness used for the 13C27 Leeks by Kershaw is 58-59 Rc IIRC. But there was talk of a sprint run of 13C27 Leek run at 64 Rc. The project got scrapped recently, but it is an example how you might have the same model in the same steel at vastly different hardnesses.

P.S. Well, I should have read more carefully. I just saw that Cobalt had and excellent example to illustrate my point.