BHN of lead, tin, antimony

[joeb33050]

Does anyone have a source for these BHNs? My google search didn't help.
Thanks;
joe b.

[Tom Myers]

Joe

I found these links

Antimony Brinell = 30 - 59

Pure Tin Brinell = 3.9

Pure Lead = Vickers = 5 ~ Brinell = 4.2

Tom Myers

[montana_charlie]

I realize they aren't your numbers, Tom, but should we believe that tin is softer than lead?
CM

[buck1]

Follow the link and page down and there it is.

http://www.lasc.us/CastBulletNotes.htm

[grumpy one]

Does anyone have a source for these BHNs? My google search didn't help.
Thanks;
joe b.

Joe,

The only semi-plausible reference I could find is the web site of EnvironmentalChemistry.com.
http://environmentalchemistry.com/yo...lectrical.html
Click on your element then read through the tedious list of properties.

Tin: Brinell 51.2 MegaNewtons per square metre
Lead: Brinell 38.3 MegaNewtons per square metre
Antimony: Brinell 294 MegaNewtons per square metre

(to convert MegaNewtons per square metre, or MegaPascals, to BHN, or kilograms per square millimetre, divide by 9.80665. So, Lead = 3.9 BHN, Tin = 5.2 BHN, Antimony = 30.0 BHN)

I tried more prestigious sources such as Smithells and the Metals Handbook but found little or nothing.

[montana_charlie]

If you can find a source for numbers that lists lead, tin, and antimony in Brinnel SI units (MPa), this is (supposed to be) the conversion to the Brinnel Hardness Number...

1(MPa) = 0.18 BHN
Therefore 38.3 (MPa) x 0.18= 6.894 BHN

The charts on the Wikipedia page for Tin (Sn) gives it a Brinnel hardness of 51 MPa.
http://en.wikipedia.org/wiki/Tin

Their page on lead shows a value of 38.3 MPa.
http://en.wikipedia.org/wiki/Lead

You have to decide for yourself what to go with, but I would sure like to get a definitive number for Tin.
CM

[grumpy one]

If you can find a source for numbers that lists lead, tin, and antimony in Brinnel SI units (MPa), this is (supposed to be) the conversion to the Brinnel Hardness Number...

1(MPa) = 0.18 BHN
Therefore 38.3 (MPa) x 0.18= 6.894 BHN

The charts on the Wikipedia page for Tin (Sn) gives it a Brinnel hardness of 51 MPa.
http://en.wikipedia.org/wiki/Tin

Their page on lead shows a value of 38.3 MPa.
http://en.wikipedia.org/wiki/Lead

You have to decide for yourself what to go with, but I would sure like to get a definitive number for Tin.
CM

Charlie, Newtons are related to kilograms by the acceleration due to gravity, 9.8 metres per second per second. Hence the 9.80665 conversion factor from MPa to BHN, which I got from one of the online conversion sites. If you accept the 51 MPa hardness for tin, this automatically gives you 5.2 BHN. I don't know where you got that conversion figure you quoted (0.18 BHN per MPa) but it does not appear to make sense in terms of physics.

[joeb33050]

Tom Myers, thanks, this is what was needed.
Buck1, there’s no source listed, my original problem. The LASC site lists BHNs of Lead 5, Tin 7 Antimony 50. These are the same as the values listed in “CAST BULLETS” on page 87, where the tin and antimony values are “app. 7” and “app. 50”. I suspect that the LASC site values come from “CAST BULLETS”.

Grumpy one, thanks for your cite and explanation.
Montana Charlie thanks for keeping us on our toes.

Here’s what we’ve got:
“CAST BULLETS” and LASC site: lead 5, tin ~7, and antimony ~50
Tom Myers/matweb.com: lead 4.2, tin 3.9, and antimony 30-59
Grumpy one/environmental chemistry: lead 3.9, tin 5.2, and antimony 30

The business of BHN and composition of lead alloys is messy, but maybe it doesn’t matter, maybe close enough is OK.

Here’s why I asked. Sometime past the CBA folks put up an alloy blending EXCEL program on the home page, and that program calculated the BHN of alloys as the weighted arithmetic mean of the BHNs of the constituents. I objected and got the BHN calculator removed.
Since then there have been requests to put back the BHN calculator, it is missed. My explanations have been met with frustration and some anger.
The only source I’ve found for estimating BHN from the composition of an l-t-a
alloy is the graph in “CAST BULLETS” on pg. 17 and again on pg. 131.
This graph is from "Type Metal Alloys" By Frances D. Weaver, B.Sc. (Mrs. Harold Haywood), see: Journal of the Institute of Metals, Vol. LVI, 1935, and is, I hope, attached.

Lyman #2 is 5% tin, 5% antimony and 90% lead, at least in some places/times.
Use lead 4, tin 5, and antimony 30, for BHN in an example.
90(%) lead * 4 BHN = 360
5(%) tin* 5BHN = 25
5(%) antimony * 30 BHN = 150
360 + 25 + 150 = 535 / 100% = 5.35 BHN as the weighted arithmetic mean of the BHN
Yet Lyman #2 is reported to have a BHN of 15.
The weighted arithmetic mean method is incorrect, I think.
My question is, am I wrong?
Thanks;
Joe b.

[grumpy one]

Joe, the idea of calculating BHN by taking a weighted average of the constituents ignores two relevant possibilities. First, it says that none of the ingredients bond together chemically to form a compound. Second, it says that none of the additives (in this case, tin and antimony) affects the crystal lattice of the matrix (in this case, lead). Both of those assertions would be blatant nonsense in the case of a lead-tin-antimony alloy. We know (courtesy of Frances Weaver) that tin and antimony combine to form the compound SbSn, which has different properties from both tin and antimony and those properties are not a linear interpolation between the ingredients. We also know from basic metallurgy that antimony precipitates into the crystal matrix of lead to cause precipitation hardening. The latter is probably the main reason for Lyman No. 2 being so much harder than your calculated nonsense value.

FWIW, I don't find the Weaver chart you attached to be all that accurate, but it seems pretty close in the case of air cooled Lyman No. 2. My reading of a blown-up version of Weaver's chart places No. 2 at 16 BHN, and a linear interpolation from my own hardness tests on slightly different alloys also comes out to 16 BHN.

As an aside Joe, in my scanned copy of Weaver's 1935 article her husband's name is spelled Heywood, not Haywood. I wouldn't bother with this trivia but since you are an author, you might be fussy.

[Firebird]

Totally agree with Grumpy, you can't predict the hardness of an alloy from the hardness of it's elements.
If you ever run any of those calculators with different starting points, (i.e. add tin and antimony to wheelweights to get Lyman #2, vs adding lead and tin to linotype to get Lyman #2) you always got different answers for the hardness of the final alloy, and in the example I gave both were wrong.
It would be nice to have a calculator to figure out hardness's for us, but until someone goes through and makes all the alloys, (varying antimony by 1/2%, tin by 1/2% and arsenic by .02%) tests the hardness of the fully normalized alloy and then publishes the results, it just isn't practical.