# Janka wood hardness vs metal hardness



## kholmz (Mar 9, 2018)

I just received a piece of Austrian Buloke in the mail. Said to be the world's hardest wood with a Janka hardness rating of 5060 lbf. My question is, how hard is this compared to metal? The Janka hardness test measures the force required to push a 11.28mm steel ball halfway into a sample of wood. I'm trying to understand how this relates to metal. It certainly has to be harder than lead or tin, but what about copper or aluminum? The problem is that I can't find any data on someone trying the Janka test on different types of metal. Metal has different tests for harness, but I can't find any conversion method between that and the Janka test. Any thoughts? 

P.S. It's not really a firewood question (unless you plan on burning Buloke), but I couldn't find a better spot for it.


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## JeffHK454 (Mar 9, 2018)

kholmz said:


> I just received a piece of Austrian Buloke in the mail. Said to be the world's hardest wood with a Janka hardness rating of 5060 lbf. My question is, how hard is this compared to metal? The Janka hardness test measures the force required to push a 11.28mm steel ball halfway into a sample of wood. I'm trying to understand how this relates to metal. It certainly has to be harder than lead or tin, but what about copper or aluminum? The problem is that I can't find any data on someone trying the Janka test on different types of metal. Metal has different tests for harness, but I can't find any conversion method between that and the Janka test. Any thoughts?
> 
> P.S. It's not really a firewood question (unless you plan on burning Buloke), but I couldn't find a better spot for it.


We use Brinell testers at work ..uses a .394 dia. carbide ball and a applied force of 3000kg ..the hardness is calculated by using the surface area of the dent the ball makes .


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## JeffHK454 (Mar 9, 2018)

..I think it's like 3 1/2 tons of force..


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## kholmz (Mar 9, 2018)

JeffHK454 said:


> We use Brinell testers at work ..uses a .394 dia. carbide ball and a applied force of 3000kg ..the hardness is calculated by using the surface area of the dent the ball makes .



Thanks Jeff. The Brinell is a similar test to the Janka but it uses a fixed force and measures the indent size in the metal. So not easily converted but I did find a formula for the Brinell test that I was able to plunk the Janka values into. 



And a found a Brinell calculator here:
https://www.ajdesigner.com/phphardness/brinell_hardness_number.php#ajscroll

So that gave me a Brinell Hardness Number for Buloke of 11.48 BHN.

Where:
lead = 5 BHN
tin = 7 BHN
pure aluminum = 15 BHN
copper = 35 BHN

So Australian Buloke at 11.48 BHN is almost as hard as pure aluminum but quite a ways off of copper. That's still pretty dam hard!


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## coutufr (Mar 9, 2018)

One more mistery solutioned by a member of the Arborist club!


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## Marley5 (Mar 9, 2018)

Very interesting, strangely enough I've always been fascinated by wood densities.

Here in the east we always hear about locust but I'm almost certain that Osage Orange is king of the woods but doubt either is Buloke.


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## Woody912 (Mar 10, 2018)

JeffHK454 said:


> We use Brinell testers at work ..uses a .394 dia. carbide ball and a applied force of 3000kg ..the hardness is calculated by using the surface area of the dent the ball makes .


Also has a great deal to do with the alloy and thickness of the material you are testing. I worked for Nucor steel, HRB scale used a very small ball, HRC scale we used a diamond indenter if I remember correctly


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## Woody912 (Mar 14, 2018)

Marley5 said:


> Very interesting, strangely enough I've always been fascinated by wood densities.
> 
> Here in the east we always hear about locust but I'm almost certain that Osage Orange is king of the woods but doubt either is Buloke.



I have some fence row grown Osage orange, annual rings 3/4" apart. Don't think it will come close to white oak, hickory, locust or red elm. Growing conditions and % of late wood have an enormous effect on hardnes. And no they are not Buloke. I saw the numbers a long time ago, we don't know what hard wood is in the US


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## svk (Mar 14, 2018)

Marley5 said:


> Very interesting, strangely enough I've always been fascinated by wood densities.
> 
> Here in the east we always hear about locust but I'm almost certain that Osage Orange is king of the woods but doubt either is Buloke.


Although density and hardness are different things. Normally the more dense a wood, the more hard it is but not always.


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## Wood Doctor (Mar 17, 2018)

svk said:


> Although density and hardness are different things. Normally the more dense a wood, the more hard it is but not always.


Also, it's Australian, not Austrian. Lignum Vitae is the densest of all hardwoods at 6.8 lb/bd ft. It takes centuries for one of these trees to reach maturity. Even Ebony tops out at only 5.8 lb/bd ft. Osage orange (hedge) is a measly 4.4 to 4.5 lb/bd ft.

Density is not the same as hardness. Is either lead or gold harder than either steel or ordinary iron? Common glass is harder yet but not near as dense as either lead or gold.


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## kholmz (Mar 19, 2018)

Wood Doctor said:


> Also, it's Australian, not Austrian.



Ah yes I meant Australian not Austrian, the spell checker had a hard time reading my mind. Thanks for the clarification.


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## Jeffkrib (Mar 25, 2018)

So what on earth is a Canadian doing with a piece of Buloke?


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## kholmz (Apr 3, 2018)

Jeffkrib said:


> So what on earth is a Canadian doing with a piece of Buloke?



I'm not sure what I will do with it yet, I just like to own rare things I guess. I also own a piece of Ancient Kauri.


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