To Quench or not to Quench

[Dieselhorses]

So I did some research (honestly) through this forum- searching for the word "quench" and oh my, the results.... everything but the question "If I want to retain my current BHN, can I let my Pc'd bullets air cool as opposed to water quenching?" Will the powder coating retain it's integrity? Going to test hardness on the 300 or so I Pc'd tonight in a week or so but just wanted to know if anyone else "air-cooled" after coating. TIA

[AR-Bossman]

There is a youtube video on this

https://www.youtube.com/watch?v=2fbjs-lErL0

[bmortell]

I thought air cooling was standard procedure for powder coating things? but ya you can do either just fine. at any point until loading you can rebake at 400 and either air or water cool to flip hardness back and forth, ive squished both flat in hydraulic press and its on there very well.

maybe im not understanding the question what do you mean retain your hardness?

[Willbird]

So I did some research (honestly) through this forum- searching for the word "quench" and oh my, the results.... everything but the question "If I want to retain my current BHN, can I let my Pc'd bullets air cool as opposed to water quenching?" Will the powder coating retain it's integrity? Going to test hardness on the 300 or so I Pc'd tonight in a week or so but just wanted to know if anyone else "air-cooled" after coating. TIA

IMHO the typical PC process could anneal a bullet. I come back to the linked article a lot.

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

They have a table for the resulting brinell hardness of bullets heated and quenched in water.

Especially interesting is the footnotes where they tested 460F with a conventional gas oven vs a convection oven. We could take from that that the temperature at 1 hour in a gas oven has not fully soaked into the bullets ??

I know if I PC bullets at 450F (oven thermometer temperature) in a convection toaster oven and air cool them. Then reheat part of the batch at 450F for another 25 minutes then water drop them in 2 days using a base to base smash test in a bench vise the water dropped bullets are much tougher than the air cooled ones.

Bill

[Dieselhorses]

I thought air cooling was standard procedure for powder coating things? but ya you can do either just fine. at any point until loading you can rebake at 400 and either air or water cool to flip hardness back and forth, ive squished both flat in hydraulic press and its on there very well.

maybe im not understanding the question what do you mean retain your hardness?

After casting these bullets BHN measures 14. I want to keep 14 and thought that if I water quenched after powder coating it would raise BHN which I don't want that to happen.

[bmortell]

ah I see, you certainly don't need to water drop after baking PC, it is common, but ive never heard of anything that says it physically helps the coating or is required in anyway, think everyone just does it so they don't have to watch metal cool for 15 minutes or to change hardness. if you have ones that were quench hardened and you want them closer to original hardness you can rebake and air cool. of course theres more negligible factors preventing you from maintaining the same 14 like age and the bake cycle even without quenching probably changes it a bit anyway, but you'll be close enough to original hardness.

[bmortell]

i don't understand the heat treating chart on the lasc link, they show basically 0 initial change? then they get hard several days later? ive water dropped ones after just 20 min baking, tested against an air cooled one 10 min later by hydraulic pressing them together and it seems very obvious one is much harder. so im not sure what to take from their info

[AR-Bossman]

i don't understand the heat treating chart on the lasc link, they show basically 0 initial change? then they get hard several days later? ive water dropped ones after just 20 min baking, tested against an air cooled one 10 min later by hydraulic pressing them together and it seems very obvious one is much harder. so im not sure what to take from their info

Yeah keep in mind you are dealing with crystalline atomic structures and the interplay of lead, tin, antimony that maybe only a metallurgical expert could really explain. But I do believe from what I've read is that these lead bullet casting recipe's we use do change hardness over time.

[Willbird]

Yeah keep in mind you are dealing with crystalline atomic structures and the interplay of lead, tin, antimony that maybe only a metallurgical expert could really explain. But I do believe from what I've read is that these lead bullet casting recipe's we use do change hardness over time.

Everything I have read does indicate some time required to achieve full hardness, and then over months, years, even decades the alloy will soften up some.....some have done testing that shows what actually happens may not be exactly what some have stated as "true".

High antimony "hard" magnum shot is an example of a protect that is sold "heat treated" ..it contains antimony and arsenic...and folks never report that it has softened up 10 years after they bought it .

Bill

[Dieselhorses]

Whole reason I started thread (and I failed to mention this at first) was because the bullets in question are all HP's and I just wanted to get the best expansion I could. I know "softer" bullets doesn't mean that those bullets will always stay together. Thanks for everyone's input!

[AR-Bossman]

Whole reason I started thread (and I failed to mention this at first) was because the bullets in question are all HP's and I just wanted to get the best expansion I could. I know "softer" bullets doesn't mean that those bullets will always stay together. Thanks for everyone's input!

I'm a newb and cast HP bullets are very cool looking but you will see in alot of testing they are NOT the easiest bullet type to get working right. Alot of testing is needed and then once a combo is found, you need to be able to repeat all conditions. I just decided to skip them for now and try to get my normal bullets to work right.

[Dieselhorses]

I'm a newb and cast HP bullets are very cool looking but you will see in alot of testing they are NOT the easiest bullet type to get working right. Alot of testing is needed and then once a combo is found, you need to be able to repeat all conditions. I just decided to skip them for now and try to get my normal bullets to work right.

I have a few different pins for this MP mold and have only tested SWC's and the "Penta's" and actually got pretty good accuracy but the real test is drilling soggy phone books I reckon (or similar). I get consistent results after finally finding the speed/technique this mold likes.

[popper]

Diesel - the trick is the RATE at which cooling takes place. Hot alloy (near slump temp and for an hour) alloy has a 'proper' structure. Quenching retains that structure. Slow cooling alloy allows a different and weaker structure to form. Atoms move around in a solid, movement is a function of temperature and time. PC is fine with quenching.

[Conditor22]

[fredj338]

I quench out of the oven, both PC & HT. I find I get a little BHN bump, like 3-4bhn. So I am fine with that & no extra work involved.

[MOC031]

I know if I PC bullets at 450F (oven thermometer temperature) in a convection toaster oven and air cool them. Then reheat part of the batch at 450F for another 25 minutes then water drop them in 2 days using a base to base smash test in a bench vise the water dropped bullets are much tougher than the air cooled ones.

Out of curiosity, alloy and what makes of powder are you using, and how long are you baking them at 450F?

I will be starting out with Smoke's black and clear colors on WW, and 450 F. is getting pretty close to the slump point in a cycling cooking oven. A water quench following half an hour at 430 F - 440 F to bake the powder paint on might leave me pretty close in hardness to what I'm doing now with conventional heat treated and lubed bullets - as long is the powder coat is okay with that.

If it's of any possible use to anyone on this thread, this is a screenshot cut 'n paste of some heat treating information Molly shared with me about 30 years ago when I got started casting for rifles. I don't know if it's been rendered obsolete by developments since then, but with the few rifle bullets I cast, it has resulted in the outcomes I need up until now.

[Willbird]

I messed up on the 450F. I used a dial type oven thermometer which proves very accurate in a larger oven. But the radiant heat environment in a small convection oven makes it read about 75F high. I was actually cooking at 375 for 25 minutes. Base to base smash test with air cooled showed a hardness bump in 1-2 days even at 375F.

I have since adjusted oven temp up so I’m consistently over 400F.

I am using Tiger Drylaq and Smokes Bacon Grease. The Tiger started working WAY better at 400F, will circle back to the Bacon Grease and I’m sure it will too.

Lesson learned about temp measurements in small areas with radiant heat sources

[Ozark mike]

I quench big bullets just so they don't get bent or dinged while warm

[MOC031]

I messed up on the 450F. I used a dial type oven thermometer which proves very accurate in a larger oven. But the radiant heat environment in a small convection oven makes it read about 75F high. I was actually cooking at 375 for 25 minutes.

I always look at dial type bimetal thermometers with a bit of a jaundiced eye. I like cooking a real good meal once in a while; my Mom had one of the old folding metal framed liquid filled oven thermometers from as early as I can remember as a little boy when we were still cooking on a coal and wood stove. I checked it in an accurate lab oven at my brother's lab about 20 years ago and it was spot on - good enough for the girls I go out with anyways. I threw the handful of dial type oven thermometers I had accumulated in the Sally Anne box. The results of my roasting and baking have gotten a lot more consistent ever since I put that old thermometer back into service.

Does just as good getting the oven ready for trays of bullets for heat treating as well.

About 20 years a friend brought over his toys from working at the co-gen plant. Two of my lead pot thermometers were junk; the one I bought from Bill Ferguson was close enough for my needs. I don't doubt that really accurate dial thermometers are out there for various uses; I probably just didn't find the right ones with my wallet in my one hand.

Anyways, I think my temperature measurement issues are mostly dealt with.

I was actually cooking at 375 for 25 minutes.

From what I got from Molly, heat treating effects don't start happening until at least a half hour at 420 F. I've been heat treating at just below 450 F. I would expect to find that 25 minutes at 375 F. later would reduce my final hardness levels.

There's probably a couple of graphs out there that could coincide: the temp versus time to get a complete powder coat cure as you drop temperature and raise time of baking versus final hardness after the annealing affects on heat treated bullet subjected to longer. Presuming the techies that specify the temp and time for a full cure with any powder paint product know what they're doing in providing that, I have no definitive way of testing how close to complete the paint cure is when time/temperature is modified. But I can test hardness before or after casting, heat treating, paint baking, etc.

[Willbird]

I had tested that exact thermometer with my Igrill and two probes and it was right on the money, in a big gas oven. But it has a LOT of surface area to absorb radiant heat from the elements in a smaller convection oven like my Oster.