Checking Hardness of blended alloy's...

[41mag]

I am sure I have looked this up and probably asked before but I cannot find either. Did find plenty of "Hardness" post though.

So when you blend up an alloy by mixing it up using somewhat known alloys, how long do you need to, or usually wait before checking the hardness and considering it a done deal?

My little proceedure is to pour up several Lee 452-255RFN's of the alloy when I blend, then throw them in a baggie with the box of ingots. I put in the date poured, and the temp it was smelted at for future reference. Then I will check them with my Cabine Tree tester on and off until I use up the ingots. That said, sometimes it changes significantly over a two week period, and sometimes it might take a month or more before it reaches it's hardest stage.

How long do you usually wait to determine what a usable number might be?

[Mike W1]

I usually check the first day or two and then again at 2 weeks.

[btroj]

Once I have an alloy made up I don't test the hardness of the alloy. I may well water drop the bullets giving them a vastly different hardness from the original alloy.

[cbrick]

I don't test ingots at all. What will effect the final hardness is the speed they cool, ingots have far more mass and take much longer to cool than the boolits made from them.

How long for the boolits to reach final BHN is directly related to the Sb percentage, a 2% Sb alloy will take longer to reach final BHN than will a 5% Sb alloy. The Sn percentage can also effect the final BHN as well as how much/fast they will age soften.

So to answer your question . . . There is no set answer, depends on your alloy. From a couple of days to a couple of weeks.

Rick

[41mag]

I usually check the first day or two and then again at 2 weeks.

Right and this is about the way I have been going about it.


I don't test ingots at all. What will effect the final hardness is the speed they cool, ingots have far more mass and take much longer to cool than the boolits made from them.

How long for the boolits to reach final BHN is directly related to the Sb percentage, a 2% Sb alloy will take longer to reach final BHN than will a 5% Sb alloy. The Sn percentage can also effect the final BHN as well as how much/fast they will age soften.

So to answer your question . . . There is no set answer, depends on your alloy. From a couple of days to a couple of weeks.

Rick

Yep I completely agree with testing full ingots as well. This is why I usually use the 2 cavity Lee 425-255 to pour up a few test bullets. I do them as though I were casting them to shoot, where I heat up the mold dipping the corner in the alloy, and when hot I pour up 4-6 or so and set them aside. This size is a pretty decent representation of most of what I pour. I have a friend who purchased a decent quantity of rane lead. After testing some of the ingots he said the hardness was all over the place. I told him the same thing, to simply melt some of it up, pour up some bullets and THEN test what he had. So far since doing so he has had MUCH more consistent readings.

My main concern is with an alloy I have blended up which I call my Low Vel HP Alloy. I am primarily using it to pour HP's which will not exceed 1000fps or if so not by much. These have been from my 45ACP and several revolvers. Using the MP HP molds has been a hoot as well as a huge learning experience, as to what alloy I can get to work with which handguns and with what loads as well.

Also due to not having a lot of WW or pure lead around to scrounge up, I have purchased most of the alloy I do have. Most of what I purchased were the Lg Iso containers, which are great for general purpose and WFN type solid bullet. However they have far more antimony in them than you need to pour a good reliable HP from. Granted the HP's poured with it DO expand, but the noses fragment off. What I wanted was something that held together from the start to finish of penetration.

in testing and reading through hundreds of post here and elsewhere I decided to try and just keep it simple, and use what I had to get the most from it. So I blended up the Iso core alloy with some pure, and some pure tin, which as best as I could figure using Bumpo's calculator, would give me a 1.5/1.5/97 alloy. Every caliber I have shot this in has expanded in the manner I was looking for. Thing is I only made up around 10# to begin with. (outlined here, Latest HP Alloy Blend, might be a winner... (http://castboolits.gunloads.com/showthread.php?164591-Latest-HP-Alloy-Blend-might-be-a-winner&) )

After a week it was running around a 10 - 10.5, after several months it creeped up to around 11.5. This is where I am now with it, and I just blended up right at 60# of it on Thursday. I tested yesterday and the first bullet hit right in between 10-1 and New WW according to my Cabine Tree tester. Or .073 if going by the actual reading. Compared to one of the other slugs which was poured up back in August of last year, and is now running around a 0.65. This very much so correlates with what you mention above, in that they harden up some, but then soften up over time.

I cannot guarantee that I mixed up the base alloys to any scientifically exact formula, as I simply multiplied out what it would take to make up the same/similar alloy using a whole Lg core which hit my scale at 30#. From there I weighed up the pure, and the tin, and blended it all together. Yesterday I poured up close to 40# of it using three different MP molds and then got curious about wait times and such.

I had also blended up some that I was hoping to use in higher velocity loads which was 1.75/1.75/96.5, again using the calculator. The alloy does wonderful at low end loads in both the 357, and the 41mag. It expands the MP 452-200 about half way to the bottom of the HP cavity from my 1911.

That said in a mid range velocity 41mag load this past weekend, I completely leaded up the bore of my Redhawk, with only 4 shots, to the point I can just barley make out the rifling. If I'm not mistaken I used 2400 with that particular load, and it still might work but I am going to retry it with some AA-9 instead, and give it a bit slower shove off.

Anyway, I appreciate the help and guidance. Hopefully this batch will preform as well as the small test batch did, and I won't need to blend up any more of it for a while.