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Doug Adams

Blade hardness

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Posted (edited)

What hardness do you like your hunting knives and edc's to be?
Doug
Jn. 3:16

Edited by Doug Adams

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It depends on the steel and geometry. Generally 59-61

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58-60 HRC is what I shoot for on an average hunting knife 

 

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Big knives, 55-58.  Small knives, 58-59.  Rarely do I let something be harder than 59, because most people can't sharpen anything harder than that.  Big knives are left softer so they don't break during the inevitable abuse they see.  With the right geometry, a blade at Rc55 can cut bone or even mild steel with no damage.  Don't get hung up on maximum possible hardness.  

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Just remember, the better the edge holding ability the harder it is to sharpen.  So, as Alan infers, you can have a hard blade that will hold an edge seemingly forever but needs a belt grinder to restore the edge or a softer blade that will dull while field dressing and skinning an elk but you can restore it's edge with a few passes on a crockery stick.

Doug

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Exactly.  In my opinion, Rc59 is as hard as anyone should reasonably want an EDC to be.  Specialized kitchen knives can be harder, and many non-knife tools.  I have a little EDC by Larry Harley that is a lovely little thing, but at Rc62 or more it is nigh impossible to sharpen.  It absolutely requires a belt grinder, it has stripped the diamonds off a diamond hone before.  It is not harder than diamonds, of course, but it is harder than the bonded metal they're affixed to.  Larry even tried to engrave his mark on it with a tungsten carbide tipped scribe in a pantograph, which is how he marked all his knives after heat-treatment.  It barely left a scratch.  

Some of this gets into the steel type and carbide size too.  That little unsharpenable blade is ATS-34, which is notorious for large chromium carbides that tear out rather than wear away.  Something with a much finer carbide structure like AEB-L (12C27), W2, or even CPM154 would take and hold a much finer edge.  Larrin Thomas over at knifesteelnerds explains all this very well indeed.  https://knifesteelnerds.com/getting-started/  and 

https://knifesteelnerds.com/2018/11/12/rockwell-hardness/

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Posted (edited)

That's weird. I am not having any trouble sharpening my hard kitchen knives. Perhaps the top quality Shapton GlassStones really help.

I suspect abrasion resistance is a much stronger factor in sharpening difficulties. Surely hardness increases abrasion resistance but not nearly as much as a good amount of vanadium/tungsten/nobium or even chromium carbides. Afterall, Japanese kitchen knives are often 63-64hrc and they sharpen those on water stones...

Edited by Joël Mercier

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