The Old Argument: Actual Brinell Measurement/Hardness

[mehavey]

A couple of days ago -- on Another Forum Far, Far Away -- the usual "which hardness tester" debate started. Suggestions ranged from $6,000 Lab equipment down to simple ball / pressure impression diameter set-ups like LEE. The ubiquitous complaint of "I can't get the LEE microscope to work..." emerged as usual.

I suggested/showed a simple printer/scanner/PhotoShop solution for a 30-1 (RotoMetals) bullet that I'd just tested using the LEE steel ball indenter:



That set off an absolute FIRESTORM in which I obviously could/wouldn't read the accepted science published/listed/specified everywhere that 30-1 is by definition BHN 9.
(Didn't I know the experts all said so?)


Well . . . No.
I have long used my own first principles calculation/test for Brinell, run against various alloys over the last 15 years.
It's fairly straightforward in both principle/test -- and calculation:

Very simple concept: Pressure (lb/sqin) which the material can withstand (i.e., quit) deforming
You press a small ball (LEE: 5/32") into the alloy at constant force (LEE: 60lbs) until the increase in depression surface area reduces the pressure (lbs per square inch -- remember?) to the point that deformation quits.

Final force on the spherical depression surface area of the material.
That's the Brinell #


But . . . still the naysayers.

To the Cognoscenti here on CastBoolits then:
The Truth us out there.
What is it?

[waksupi]

If the Cabin Tree testers are still available, I found them to be the most consistent with the least fuss.

[Hick]

Well thought out-- never mind the firestorm. The thing that amazes me sometimes is how uptight people get about the bullet hardness. I have a bar of Lyman #2 I keep around for testing mystery alloy. I want my pistol bullets to be softer and my rifle bullets to be at least as hard. When I get my hands on mystery alloy I squeeze a ball bearing between the #2 and the mystery piece in my vice. I just compare the diameters of the indents-- the softer one will be larger-- to decide what to do with the alloy.

[mehavey]

Cabin Tree reference chart still has the Lead/Tin alloys w very high Brinell numbers.
Has anyone here done any actual/independent testing?

[charlie b]

Here ya go

http://www.lasc.us/Shay-BHN-Tester-Experiment.htm

[mehavey]

Here ya go
http://www.lasc.us/Shay-BHN-Tester-Experiment.htm

Those are all for very High/very Hard alloys (well above 20 BHN)
The question seems to be what's happening w/ the classic Low Tin/Lead ratios.
How soft are those.... ?

[Larry Gibson]

Here ya go

http://www.lasc.us/Shay-BHN-Tester-Experiment.htm

The important lesson from that extensive test and the tests conclusion; "So yes, these testers are a valuable asset to the bullet caster. Does my tester say an alloy is 18 BHN and the lab says no . . . its 20 BHN . . . Well, so what? It doesn’t matter as long as mine always says 17-18. Consistency matters, an exact match to lab results does not. If your casting technique is consistent enough to keep your bullets within 1 BHN and your BHN testing tool is consistent enough to measure within 1 BHN even the most demanding caster should be good to go. Alloy consistency is important for long range top end loads grouping and these tools are an important "aid" in assembling consistent cast bullet loads."

BTW; I've cast a lot of 30-1 alloy and never had a BHN of 9, regardless of what it says in the NRA Cast Bullet Handbook, using a Lee testor in a micro scope stand. I got consistent BHNs between 6 and 7.5 with multiple readings per sample. That's close enough for me as I know how much lead and tin were/are in the alloy. That BHN figure works for me.

[mehavey]

Just did a LEE retest from a 30:1 RotoMetals casting of 44-40s sitting from some 7 years ago:



RotoMetals is nothing if not consistent.

[charlie b]

Those are all for very High/very Hard alloys (well above 20 BHN)
The question seems to be what's happening w/ the classic Low Tin/Lead ratios.
How soft are those.... ?

Like Larry said, that was only a comparison of the different testers.

I've never worried about it. The only thing I want soft lead for is my muzzleloader slugs and those can be in the 1-30 or so range. For my rifles I just buy Lyman #2. Pistols I don't care either. I ran straight COWW for decades and never measured bhn.

If you want to know for sure then send it to a certified lab who uses calibrated equipment, if you can find one.

[mehavey]

Charlie(b), I'm more interested to know why the accepted Lead/Tin alloys are
rated so high when really simple tests like LEE clearly indicate they are not.

Charlie(M) mentioned 20-1 being unequivocally 7.8 some time back, which is
consistent with my own 1st-principle Brinell definitions/processes.
https://castboolits.gunloads.com/sho...=1#post1852750
Does anyone [ including Charlie(M ]) recollect the source ?

More important (to me) than actual numbers when all dust settles, is why the absolutely
blatant discrepancy? w/ what should be such a simple alloy characteristic/measurement
method.

[charlie b]

Send some off to a lab and see who is right? Until then you have a comparison from your measurement device to base other measurements on.

[ioon44]

I have always used the LBT hardness tester it is close enough for my needs.

[mehavey]

I am less concerned the 'what,' so much as the WHY a direct Brinell tester
(Lee 5/32" ball impressed at 60-lbs pressure) provides exactly-correct
Brinell readings for certified pure lead (5), and certified Lyman#2 (15) ...

But (apparently ?) not for certified lead-tin alloys in between the two.

A spring constant is a spring constant is a spring constant . . .
Something is very wrong.

[DAVIDMAGNUM]

If the Cabin Tree testers are still available, I found them to be the most consistent with the least fuss.

https://cowboybullets.com/Lead-Tester_p_57.html

I have used one for years and have compared it to foundry certified samples from pure to Linotype. I have found it to be consistent. I truly don't care about the actual BHN, I just want to replicate a known alloy for my firearms and the purpose at hand.

side note: I don't need a tester to tell me that 30-1 bullets are soft. Accidentally dropping them on my concrete floor lets me know it......every time.

[fc60]

Greetings,

https://www.zwickroell.com/industrie...test-iso-6506/

"The test force is to be selected so that the average indentation diameter d is between 0.24 D and 0.6 D."

The Lee tester can only measure between 0.094" and 0.038" diameter of the test impression.

Cheers,

Dave

[mehavey]

THANK You for that article -- great info in practical Brinell applications.

That said, here are the indent range limits the article implies:


The ARTICLE also mentions the indenter & forces associated w/ various Brinell#'s in Lead:
- BHN 5 - 25: Indenter of 5mm
- Force: 55 lbs

LEE's system has an indenter of 4 mm (5/32")
and uses a Force of: 60 lbs

All-in-All . . . a little over-force/under-indent, but a pretty fair match-up within Brinell# limitations

Lee reasonably ascribes to those limitations in their application chart:


So 30-1 w/ an (assigned) BHN of "9" should be well within the LEE system -- no problemmo.


But problemmo it is.

So . . . .
- I've got a new (2nd) LEE tester coming in Tuesday
- I've contacted a local metallurgy lab

Film at Eleven . . . .

[MT Gianni]

Like it was said above, you want a repeatable alloy. If your alloy test to 6 bhn, and it shoots well it doesn't matter how it compares to another tester as long as you can make it again.

[mehavey]

you want a repeatable alloy.

Not only consistent alloy, but consistent science.
(Otherwise we're just holding a wet finger in the air...
...and hoping.)
)



* Notice I didn't say "settled" science

[Shopdog]

I'm interested in the $6k lab equipment. Have a name,or type?

We have 3 distinctly different pieces of kit here. 1st is a beam type torque wrench attached to an otherwise plain jane Lyman 450. It is EXTREMELY repeatable for plastic deformation.

#2 is a very nicely finished vertical impact tester. Designed after studying Charpy equipment.

#3 is a heavily beefed/scaled up,"accurized" cabine tree.

One not so minor detail on Lee testers,and not bashing them.... just sayin. They aren't direct reading. You're opening up,or encouraging "noise" by having to take a reading by interpretation of the input. Where as the cabine tree along with some others are direct reading. The Wilson style hardness testers are also direct reading.

[charlie b]

Interesting mix. When my father-in-law started casting he was intent on finding hardness as well. He had worked with Rockwell equipment (worked on explosives testing) so he built his own on a Lee turret press. He was also a machinist so he used the lathe and mill to make all the components necessary. His setup was within tolerance of the samples he tested at the lab. From his description the dia of the test ball was key to accuracy. He had two different ones for different alloys of lead.