The Great SnSb alloy Experiment

[PBaholic]

I made up a bunch of alloy, all utilizing the same amount of Sn and SB (A.K.A SnSb). Calc is RotoMetals calculated amount. My measuring method is accurate to +/- 0.5 BHN on the lower end of the scale and +/- 1 BHN on the upper part of these measurements.

[Hick]

Excellent data-- Thanks. I use a lot of 90/5/5 and have been assuming about 16 BHN. Your data fits that nicely after 48 hours. I don't have a proper hardness tester so I appreciate you doing the work.

[KYCaster]

I made up a bunch of alloy, all utilizing the same amount of Sn and SB (A.K.A SnSb). Calc is RotoMetals calculated amount. My measuring method is accurate to +/- 0.5 BHN on the lower end of the scale and +/- 1 BHN on the upper part of these measurements.

Would you please describe the measuring method that gives you +/- .5BHN accuracy.

Thank you
Jerry

[farmbif]

have you cast any bullets? how are the sizes compared to wheel weights or #2

[Cosmic_Charlie]

Really great experiment you did there. You can actually see the dents in the samples getting smaller.

I just ordered a Lee hardness tester after checking what I thought was coww alloy with pencils. Came up with a bhn of 10. So cutting it 50/50 with pure has had me shooting some really soft bullets.

[PBaholic]

Would you please describe the measuring method that gives you +/- .5BHN accuracy.

I use Brinell's method for determining hardness, where you push a ball bearing into alloy and measure the diameter of the indentation with a digital calipers.

I use a drill press, with a bathroom scale to measure the weight. I drilled a 1/4" hole in a steel rod, and inserted a 1/4" ball bearing, which sticks out halfway. It's important to use a real ball bearing here, to get a perfect diameter. 200 Lbs is a nice weight that is easily obtained in the drill press, and it will give you a more accurate measurement as it is a significant pressure to get into the surface of the alloy. The weight isn't critical, so it's not like 197 or 203 Lbs makes that much difference.

I use magnification to measure the diameter, and lots of good light. The accuracy suffers a little on the higher end of the the BHN scale, as the diameter gets small, so I'm probably only +/- 1.0 at around 20.

[PBaholic]

have you cast any bullets? how are the sizes compared to wheel weights or #2

I cast about 300 Lbs of .38/.357 and .45ACP/.45LC every year. My .45ACP is a 230 grain Round nose with a Lee mold. I shoot for about 10 BHN, as I powder coat. At BHN 10 my lead content in the alloy is higher than what Lee expected you to use as an alloy, so my boolits are heavier than 230 grain. I don't pay real close attention to this, but most of them come out in the 238 to 240 grain range.

[PBaholic]

Really great experiment you did there. You can actually see the dents in the samples getting smaller.

The front side dent was the 4 hour one. I did the rest on the back, as you need a fairly smooth surface to get good results.

The 24 hour dent is at 11 O'Clock, and then progress going clockwise.

[rking22]

Execelent data, thank you for the effort and posting for us all to profit.

[JM7.7x58]

Good work!
Thanks
JM

[William Yanda]

Thanks for sharing.

[KYCaster]

I use Brinell's method for determining hardness, where you push a ball bearing into alloy and measure the diameter of the indentation with a digital calipers.

I use a drill press, with a bathroom scale to measure the weight. I drilled a 1/4" hole in a steel rod, and inserted a 1/4" ball bearing, which sticks out halfway. It's important to use a real ball bearing here, to get a perfect diameter. 200 Lbs is a nice weight that is easily obtained in the drill press, and it will give you a more accurate measurement as it is a significant pressure to get into the surface of the alloy. The weight isn't critical, so it's not like 197 or 203 Lbs makes that much difference.

I use magnification to measure the diameter, and lots of good light. The accuracy suffers a little on the higher end of the the BHN scale, as the diameter gets small, so I'm probably only +/- 1.0 at around 20.

Thanks for the description.

Jerry

[Evoken]

Very cool. I appreciate the graph work and testing you and many others post on this site. I knew that alloys get harder over time, but had no idea that some get that hard and take 2 months to get there. Interesting indeed.
It appears to me based on your graph that you get the most bang for your buck so to speak out of 5%. The hardness comes up exponentially until that point and kind of peters out after that. That is if I am deciphering your charts correctly.

[PBaholic]

It appears to me based on your graph that you get the most bang for your buck so to speak out of 5%. The hardness comes up exponentially until that point and kind of peters out after that. That is if I am deciphering your charts correctly.

That depends on what BHN you are looking for. By 5% I assume you mean 90:5:5, which is a common alloy, purported to be BHN 15.

My reason for doing this experiment was to determine the hardness of alloys, where the Sn and Sb were equal, especially near the BHN 10 area. I PC, so my boolits can be in the BHN 9-10 range, and I'm having a harder time finding Harder alloys like Linotype to mix with my lead.

I was hoping to find a magical point, where BHN was maximized, along the line where Sn and Sb are equal, but this didn't materialize.

The chart is a Ternary Phase diagram PbSbSn alloys. There are some interesting occurrences, like the point H, which is the mixture for Linotype, and Point I, which is the lowest melting point of any PbSnSb alloy. The 3 digit numbers are the melting points of the alloy. The green line is the point where SbSn are equal.

I'm not a Metallurgist, but just trying to figure some of this stuff out.

[Evoken]

Yes, I was referring to the 90/5/5, lyman#2. It seems based on your chart that it gains the most hardness over time. That is what I had meant.
At any rate, I have learned so much in such a short time from this site and gentleman like yourself. For that I thank you.
Ken

[Cosmic_Charlie]

I have some rifle boolits I cast with 95,5,5 many months ago. I will test them.

[Cosmic_Charlie]

Came up with about 16.6 But I did not test after casting. So starting out at 15 it got roughly 10% harder over time which correlates with your results.

[popper]

IMHO you will find that the BHN is the same for just Sb. The SbSn content is VERY small. SbSn is formed but it is called an intermetallic, i.e. as it cools it changes back to Sb & Sn. WD will give more SbSn.