Carbide hardness data

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Dec 21, 2006
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I am trying to compile a list of the hardness of carbides (and abrasives) commonly found in knife steel and sharpening stones, for my library and future reference, but it's proving to be more challenging than I thought, particularly because the HRC scale usually doesn't go much past 70, and it is the Rockwell C value of carbides I am most interested in. I've cross referenced with given Knoop or Vicker's values on a few of them, but I am seeing contrary data depending on the source. Does anyone have this data and willing to share? I'll post what I have below, some of it doesn't make sense to me, like SiC being harder than VC, that one directly from a Vicker's hardness chart. Thanks for any corrections and input.

Hardness of Alumium Oxide (corundum): approx 82HRC (2035 Vickers)
Hardness of Chromium Carbide (Cr23C6): approx 77HRC (1650 Vickers)
Hardness of Chromium Carbide (Cr7C3): approx 83HRC (2100 Vickers)
Hardness of Tungsten Carbide (WC): approx 84HRC (2400 Vickers)
Hardness of Vanadium Carbide (VC): approx 89HRC (2800 Vickers)
Hardness of Silicon Carbide (SiC) (Crystolon): approx 90HRC (3200 Vickers)
Hardness of Iron Carbide (Cementite): approx 70HRC (1150 Knoop)
Hardness of Moly Carbide (MoC): 75 HRC approx
Hardness of Niobium Carbide (NbC): ? HRC approx
Hardness of Diamond: approx 1 million HRC (ha ha!)
 
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ok, da book(Tool Steels by Roberts and Cary) say
Cementite in plain carbon tool steel: 1150 knoop
Chromium carbide (Cr7C3): 1820 knoop
Aluminum oxide abrasive: 2450 knoop
Vanadium carbide: 2520 knoop or 84 Hrc
tungsten carbide in carbide tool bit: 82 Hrc
(Fe, W, Mo)6 C in HSS: 75 Hrc
from Google search of abrasive hardness
Diamond: 7000 knoop
CBN: 4000-5000 knoop
SiC: 2400 to 3700 knoop
ceramic alumina: 2000-2600 knoop
hope that helps
 
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MC carbides include vanadium, niobium, titanium, tantalum, etc., all about the same hardness.

Moly carbides and tungsten carbides are similar.

Cementite is in the high 60s hrc.

Lots of carbides have several elements in them. Combinations of chrome, moly, vanadium, tungsten etc. are possible. Changes the hardness of the carbide.

Some steels are designed to produce one type of carbide like vandis 4 extra and 3V.

Steels like M390,Elmax, and high speed steels have complex carbides.

Hoss
 
Thanks guys. I've updated my OP to include some of the data provided. It proved to be a lot more challenging than I thought, as there aren't any charts that show a good comparison between the different hardness values like HRC to Vickers to Knoop, especially when talking very hard stuff like carbides. Surprised to see that Silicone Carbide, in many of the data online, approaches, and in some charts, exceeds the hardness of vanadium carbide.

Please take that chart, and the values presents, loosely, for the reasons stated above. Will continue to update/improve as better data comes around.
 
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Larrin , that's a nice one !
I've looked at these questions in the past and it always got more complex and confusing the deeper I got. Crystal structures , bonding type [metallic or molecular ] , melting point etc. etc. Ain't metallurgy fun !
 
Larrin , that's a nice one !
I've looked at these questions in the past and it always got more complex and confusing the deeper I got. Crystal structures , bonding type [metallic or molecular ] , melting point etc. etc. Ain't metallurgy fun !
No ! It's easier to understand Einsteins theory of relativity :mad:
 
No ! It's easier to understand Einsteins theory of relativity :mad:

For me I finally got it all nailed down. No problem. Simplicity it's self. Just two formulas :
Formula #1
Benchmade + Ritter + Griptilian in M390 = cuts stuff, sharpenable without scratchy diamonds, stays sharp LONGTIME.

Formula #2
Spyderco + M4 = cuts stuff, sharpenable without scratchy diamonds, stays sharp LONGTIME.

Everything else is just highly suspect deserts :
"Oooooh what's those green and pink sprinkle things ?"
"I don't know about combining jalapeño and chocolate but I guess I will try it"
"Are you sure we need to set it on fire before we eat it ? ? ? . . . ooookaaaa​

Oh well at least the main course was good.

PS: why two formulas then ? Can't we cross out one of these redundancies ?
Nah
Formula #1 contains the subtle, unreal number and quantum singularity ; stainlessness.
In case I ever really feel I need to explore that realm of the know universe .
 
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