joeb33050
11-06-2005, 12:38 PM
Some data on BHN and Tensile Strength
Here's a NIST site showing a collection of data from various sources.
www.boulder.nist.gov/div853/lead%20free/solders.html
Database for Solder Properties with Emphasis on New Lead-free Solders
Release 4.0
1. Table 1.18 gives the BHN of the eutectic alloy, 63% Tin, 37% Lead, as 17.
Table 1.2 gives the tensile strength of this alloy as 4442 psi, 30.6 MPa
To check the MPa number: The Pascal, Pa = 1.45 * 10^-4 psi.
The MPa is then 1.45 * 10^-4 * 10^6 = 1.45 * 10^2 psi.
The Table 1.2 figure of 30.6 MPa = 1.45* 10^2 * 30.6 = 4437 psi which looks close enough to 4442 psi for all the rounding going on.
Some estimate tensile strength at 1422 * BHN. Then 17*1422 = 27174 psi, which is a lot higher than the Table 2 4442 psi.
2. www.lasc.us/CastBulletNotes.htm
This site, among others, shows the hardness of 1:10 tin:lead alloy as BHN 11, and the hardness of 1:20 tin:lead alloy as BHN 10.
Using the 1422 factor:
1:20 BHN = 10 * 1422 = 14220 psi.
1:10 BHN = 11 * 1422 = 15642 psi.
Table 1.14 on the NIST site shows Tensile strength of 5% Tin 95% Lead alloy as 4190 psi. Compare with 14220 psi just above.
That table shows Tensile strength of 10% Tin, 90 % Lead alloy as 4400 psi. Compare with 15642 psi just above.
(I understand that 95:5 lead:tin isn't exactly 20:1 lead tin.)
Note that Table 1.14 gives the Tensile strength of the eutectic alloy as 6700 psi, and Table 1.2 gives the Tensile strength of the eutectic alloy as 4442 psi. Certainly these numbers do not agree, but the disparity between these numbers and the "1422" estimates is much greater.
3. This site is about engineering fundamentals.
http://www.efunda.com/materials/solders/tin_lead.cfm
The table shows the Tensile Strength of:
5% Tin:95% Lead at 28 MPa = 4060 psi.
If BHN is 10(LASC above), 10 * 1442 = 14420 psi. The 1442 factor.
10% Tin and 90% Lead at 30 MPa = 4350 psi.
If BHN is 11(LASC above), 11 * 1442 = 15862
63% Tin and 30% Lead at 37 MPa = 5365 psi. Note that this is between the Table 1.2 4442 and Table 1.14 6700 psi.
If BHN is 17 (Table 1.18, NIST site), 17 * 1442 = 24514
4. Here is the Mountain Molds site.
www.mountainmolds.com/bhn_psi.htm
Tensile strength is estimated at psi = 375 * BHN + 500
Then a 10 BHN alloy would have a Tensile strength of 10*375+500 = 4250, "1442" factor is 14420 psi.
An 11 BHN alloy....11*375+500 = 4625 psi
A 17 BHN alloy.....17*375+500 = 6875 psi.
Summary all in psi, 1,2,3,4 refer to par. above.)
"1422" 1 2 3 4
Eutectic BHN 17 24174 psi 4442 6700 5365 6875
95:5, 20:1 BHN 10 14420 psi 4190 4060 4250
90:10, 10:1 BHN 11 15862 psi 4400 4350 4625
Unless I'm making a big mistake here somewhere, estimating Tensile strength by multiplying BHN by 1422 is completely wrong.
Please tell me if I've gone wrong here.
joe b.
Here's a NIST site showing a collection of data from various sources.
www.boulder.nist.gov/div853/lead%20free/solders.html
Database for Solder Properties with Emphasis on New Lead-free Solders
Release 4.0
1. Table 1.18 gives the BHN of the eutectic alloy, 63% Tin, 37% Lead, as 17.
Table 1.2 gives the tensile strength of this alloy as 4442 psi, 30.6 MPa
To check the MPa number: The Pascal, Pa = 1.45 * 10^-4 psi.
The MPa is then 1.45 * 10^-4 * 10^6 = 1.45 * 10^2 psi.
The Table 1.2 figure of 30.6 MPa = 1.45* 10^2 * 30.6 = 4437 psi which looks close enough to 4442 psi for all the rounding going on.
Some estimate tensile strength at 1422 * BHN. Then 17*1422 = 27174 psi, which is a lot higher than the Table 2 4442 psi.
2. www.lasc.us/CastBulletNotes.htm
This site, among others, shows the hardness of 1:10 tin:lead alloy as BHN 11, and the hardness of 1:20 tin:lead alloy as BHN 10.
Using the 1422 factor:
1:20 BHN = 10 * 1422 = 14220 psi.
1:10 BHN = 11 * 1422 = 15642 psi.
Table 1.14 on the NIST site shows Tensile strength of 5% Tin 95% Lead alloy as 4190 psi. Compare with 14220 psi just above.
That table shows Tensile strength of 10% Tin, 90 % Lead alloy as 4400 psi. Compare with 15642 psi just above.
(I understand that 95:5 lead:tin isn't exactly 20:1 lead tin.)
Note that Table 1.14 gives the Tensile strength of the eutectic alloy as 6700 psi, and Table 1.2 gives the Tensile strength of the eutectic alloy as 4442 psi. Certainly these numbers do not agree, but the disparity between these numbers and the "1422" estimates is much greater.
3. This site is about engineering fundamentals.
http://www.efunda.com/materials/solders/tin_lead.cfm
The table shows the Tensile Strength of:
5% Tin:95% Lead at 28 MPa = 4060 psi.
If BHN is 10(LASC above), 10 * 1442 = 14420 psi. The 1442 factor.
10% Tin and 90% Lead at 30 MPa = 4350 psi.
If BHN is 11(LASC above), 11 * 1442 = 15862
63% Tin and 30% Lead at 37 MPa = 5365 psi. Note that this is between the Table 1.2 4442 and Table 1.14 6700 psi.
If BHN is 17 (Table 1.18, NIST site), 17 * 1442 = 24514
4. Here is the Mountain Molds site.
www.mountainmolds.com/bhn_psi.htm
Tensile strength is estimated at psi = 375 * BHN + 500
Then a 10 BHN alloy would have a Tensile strength of 10*375+500 = 4250, "1442" factor is 14420 psi.
An 11 BHN alloy....11*375+500 = 4625 psi
A 17 BHN alloy.....17*375+500 = 6875 psi.
Summary all in psi, 1,2,3,4 refer to par. above.)
"1422" 1 2 3 4
Eutectic BHN 17 24174 psi 4442 6700 5365 6875
95:5, 20:1 BHN 10 14420 psi 4190 4060 4250
90:10, 10:1 BHN 11 15862 psi 4400 4350 4625
Unless I'm making a big mistake here somewhere, estimating Tensile strength by multiplying BHN by 1422 is completely wrong.
Please tell me if I've gone wrong here.
joe b.