rockwell value?

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penguinsuitb

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May 8, 2011
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My i showed my grandpa my new knife and he asked me what the Rockwell value of it is. I have no idea what that is, could someone tell me what exactly that is and how i could find that out it would make me happier then a penguin :)
 
It's the scale that determines the "hardness" of a particular steel. There are charts which show the rockwell potential of most steels, however the final result comes down to the heat treat, so 2 steels of the same composition can differ in actual hardness.
 
Look up the knife on the manufacturers website and it should tell you the hardness. It might be called HRC. If it doesn't say and is a cheap knife then its probably about 55. If you're lucky.
 
Knives and similar steel tools are measured in the Rockwell C scale. Machetes will go about 45-50 HRC. Most knives will be 57-59. Some super steels can do 60-61 without being brittle.

In general, the harder the steel, the less likely it is to dull. Softer edges will roll and wear easier.

In heat treat, knives are taken to full-hard, then tempered back down to their final hardness. This can be anywhere from 60-65 HRC, tempered down to 57-60ish.
 
Also just to add on, older knives will run lower, mid-50's, and until the 60's-70's heat treating was very hit or miss. Every once and a while, you'd get knives with HRCs way off from the stated hardness goals, I mean like Rc's in the 30's-40's were a somewhat common thing. Just a historical note.

:).
 
http://en.wikipedia.org/wiki/Rockwell_scale

http://www.gordonengland.co.uk/hardness/rockwell.htm

It's worthwhile adding that there are several Rockwell scales. The one of interest to knife people is the Rockwell "C" scale. You may occasionally see a hardness posted as xx HRC.

Anything above 55 is of interest to us. 59-60 is very good. 60-65 is extreme.

If I remember correctly, the scale itself goes to 100, but the measuring equipment won't go past 80.

It is also worth knowing that, when comparing results from different machines, the closest you can say is that the reading is ±1. So if I have one knife from one manufacturer that they measured at 58 and another knife from another manufacturer that they measured at 56, it is impossible to say whether one is actually harder than the other.

I get interested if there is a 2-point difference in hardness. A one-point difference from different manufacturers is in the measurement noise. Of course if all the measurements are done on the same machine, a 1-pt difference is significant.
 
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