knife hardness

EdCaffreyMS

Forum Owner - Moderator
#2
Whew! That can be a can of worms! :) Generally you can find specific max hardness of a given steel in the particular steel's heat treating info.

Where the "worm" part comes in is that many newer/less experienced individuals have it in their mind that "harder is better"..... not necessarily true. Part of being a knifemaker is find that "sweet spot" in a steel's hardness range that offers the benefits that the individual knifemaker deems appropriate.
 

scott.livesey

Dealer - Purveyor
#3
where is a good place to find info on how hard different kinds of knives should be?
Doug
Jn. 3:16
the issue is the word "Should", which implies anything else is wrong. most steels have a hardness range that is also high toughness. also look at where the knife came from. harder steel is harder to grind, so most commercial knives have lower hardness numbers so they are cheaper to make. in a hand made knife, the hardness is selected for best performance rather than easiest to make. look here http://www.epicedge.com/shopdisplaycategories.asp?id=855&cat=Materials, most list hardness. then google the blade type and go look at others.
 
#5
you get fairly blunt tools that takes impact, and you get very sharp tools that must cut lots - but dont get beaten up... pick those steels that were designed for the type of tool you want and use the steel manufacturer's range of hardness to make heat treat decisions...

for a sharp knife i like hardness above RC62... for a blunt knife, i like hardness above rc60, but just below rc60 can be better if you don't mess up the heat treat to achieve it... if i wanted to cut nails i would buy a cold chisel...
 
#6
one way would be make 3 or 4 knives same shape and grind, same steel. temper one at 325F, the second at 375F, the third at 425F. attach a basic handle then use them. you may be able to see differences in performance, might not. it has been said that blade shape, type of grind, and thinness at the edge effects performance at lot more than hardness.
 
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