Lead Hardness Data for Quenching & Aging for Newbies Like Me

[EMR]

The info herein is directed at other newcomers to the casting world who learn better through proof in empirical evidence. As always, please let me know if anyone notices any glaring mistakes or inaccuracies.

*Cliff notes:

1) Water quenching dramatically increased hardness of lead over air cooling.
2) Aging over time does increase hardness of lead.
3) PC'ing boolits at 400 degrees does soften lead hardness 34%-44% directly after baking and cooling.
4) Quenching boolits directly out of the PC oven does in fact increase lead hardness by 19%.
5) The Elvis Ammo Low heat baking method for PC has 26% higher lead hardness directly after baking and cooling over simple air cooling.

As a fairly new caster, I've learned many things from the vast catalogues of info here at castboolits. The general Do's & Dont's of casting are repeated here a million times. And with some luck, I've managed to follow the repeated guidelines with a relative amount of success for my pistols (ie: no leading and acceptable accuracy).

That said, I've always taken everything said here about water quenching and boolit aging for face value. And I wanted to see for myself the differences. Below are the HBN data collected over time and with different types of powder coating baking.

Materials used:
358130 boolits from a MP mould cast at 750 degrees.
Range scrap lead from The Captain (I know that lead with a known mixture of constituents and antimony would have been ideal, but honestly this is what I have on hand)
Powder coating from Smoke
Toaster Oven Controlled by PID
Lee Hardness Tester

Methods Used:
Normal PC'ing @400degrees at 15 minutes.
Elvis Ammo low heat method:

225 degrees at 5 minutes
240 degrees at 7 minutes
244 degrees at 11 minutes
247 degreees at 12 minutes

*all percentages are generally compared to the air cooled boolit hardness at initial casting unless otherwise specified.

Day 0 (initial casting):

Air cooled: 8 BHN
Water Quenched: 8.2 BHN (2.5% increase)

+12 hours:

Air cooled: 11.8 BHN (47% increase)
Water Quenched: 14.3 BHN (78.7% increase)

+3 days:

Air cooled: 12.5 BHN (56.2% increase)
Water Quenched: 16.6 BHN (107.5% increase)

After Standard Powder Coating:

Air cooled: 8.2BHN (2.5% increase from base(34.4% decrease from before powder coating))
Water Quenched: 9.2BHN (15% increase from base(44.5% decrease from before powder coating))

Air cooled Boolit Water quenched directly after PC: 9.8BHN (increase in 19% over air cooled boolit after PC'ing)

After Elvis Ammo Low Heat Powder Coating (*all pass smash test*)

Air cooled: 10.4BHN (30% increase) (26% increase over air cooling after PC'ing)
Water quenched: 11.8BHN (47.5% increase)

+4days:

Air cooled: 16.6 BHN
Water Quenched: 19.3 BHN

Regular PC:
Air cool: 15.4 BHN
Water Quenched: 12.5 BHN

Elvis Ammo:
Air cool: 11.8 BHN
Water Quenched: 11.8 BHN

+5 days: TBD

+1 week:TBD

+2 weeks:TBD

+3 weeks: TBD

+4 weeks: TBD

[dimaprok]

Great data. Now try my method. (Dima's high heat method) Bake for 20 min @ 450 degrees and water quench immediately. You will gain even more hardness.

Sent from my SM-G950U1 using Tapatalk

[EMR]

Great data. Now try my method. (Dima's high heat method) Bake for 20 min @ 450 degrees and water quench immediately. You will gain even more hardness.

Sent from my SM-G950U1 using Tapatalk

That’s interesting because the reason I compared 400 degrees vs the low heat method was the theory of annealing at higher temperatures. And so far my data does show a correlation.

I’ll try your method but I’m curious as to what hardness you’ve managed?

[dimaprok]

ThatÂ’s interesting because the reason I compared 400 degrees vs the low heat method was the theory of annealing at higher temperatures. And so far my data does show a correlation.

IÂ’ll try your method but IÂ’m curious as to what hardness youÂ’ve managed?

I am using wheel weights alloy so it cannot be compared directly. You anneal when you let it air cool but you temper / harden when you quench. The higher the temperature you raise the harder BHN you'll obtain this has been documented very well by Glen E. Fryxell. I've measured BHN up to 33 when bullets reach near melting point. The problem was old oven was overheating and not consistent so some bullets that were not heated this high were not as hard. I just got new oven from thrift store that has much finer control over temperature. With old oven at 450 some bullets began to melt because it was overheating. I did time lapse recording of my new oven with 2 thermocouple sensors and it's much more accurate because the tray sits higher from heating element. I plan to do quite a bit of testing with heat treating and baking at different temps. I should mention my WW alloy has 3% added tin (pewter) that has been enriched with copper about 10% of copper in the tin and that makes BHN harder. I strongly recommend you do your testing with known alloy like WWs otherwise it's hard to compare data.

[dimaprok]

Another thing I should add is that working with WW has advantage because of small amount of arsenic which acts as catalyst to harden. You can get WWs harder than Linotype because of this. Even diluted 50-50 mix of WW and pure lead produced BHN in 20s when water quenched. Linotype officially is 22 BHN.