Heat treating woes

[milkman]

Whut am I doing wrong here? Just got a new Lee hardness tester and the blame thing is driving me crazy. I think ignorance really was bliss. I tested some boolits that I had heat treated (420 deg, 30 min) about 6 months ago and they were in the 15 bhn range, I thought they were a little too soft so I cast some water quenched and found they were SOFTER, about 12 bhn, so smart feller that I am, I told myself "self, no problem, just stick them in the oven for awhile" I put about 100 in an old deep fryer basket, the bottom lined with aluminum foil, in the oven at 440 degrees for 45 minutes and had them in ice water in less than 3 sec. probably less than 2. When I checked them they were still about 12 bhn. Everything was straight wheel weights. Got any ideas?

[BlueMoon]

I don't know that much about heat treating but bought a little oven to do that in. Then I bought 50lbs of lino-monotype and my heat treating got side-tracked. I've read of guys heat treating for 1 hour at 450* or so and then water dropping and also, your boolits will get harder after a week to a month later.

Bill

[BABore]

Try testing some pure lead (5 Bhn) and air cooled WW's (9-11 Bhn) and see what you get. If they read low you have a calibration problem with your tester. You can either send it back or use a conversion factor for correction.

Pure Lead = 5 Bhn
Your Reading = 3 Bhn (example)

5 divided by 3 = 1.667

Multiply your hard bullet reading by 1.667 and there you go. You should calculate out a couple of known hard materials and average your correction factors for better accuracy.

Other causes could be the antimony content of your WW's or, to a lesser extent your heat treat procedures. They actually sound ok though. I do mine in a 425 F oven for 60 minutes. You may want to seperate the bullets a bit, rather than just dumping them into a pile. I keep mine on their bases and seperated. You may not be getting full heat to the middle of a pile. If everything else is ok you can try adding some magnum lead shot to your next batch at 1/4 cup per 10 lbs of alloy.

[w30wcf]

milkman,
Try waiting 24 hrs. and retest. They will definitely be harder if there was arsenic in your w.w. and your oven temp. was correct.

Patience........
w30wcf

[milkman]

babore, Good thought--- I did try reading some pure lead and the impression was too large to read. I tried a ww ingot but I don't recall what reading I got. I will retry.

w30wcf - I will definately try again tomorrow, but I didn't thing it would make that large a difference. I was expecting closer to 20 than to 12.

[BABore]

Oops, I meant arsenic not antimony. Mag lead shot for arsenic, yeah yeah that's it.

[carpetman]

If your hardness tester is off---it may not be linear. If you are having to juggle the number to come up with what you think it should be,why measure? Just guess to start off with.

[Bass Ackward]

If your hardness tester is off---it may not be linear. If you are having to juggle the number to come up with what you think it should be,why measure? Just guess to start off with.

Yep. Ray is correct. There is no garantee that any tester will be linear. Theoretically, they should. And I have no idea if mine is accurate, but it does come out to what most say certain mixes is supposed to be.

Milkman,

The easiest way to know is to take a couple of bullets that you want to know from something that should be soft and something that should be hard and then send them off to someone else to test on their unit. I would be glad to help if you want to know for sure. Shouldn't cost much to send 2 bullets through the mail. IF you want to do this, send me a PM and I will give you my address.

[35remington]

30wcf is right-it takes about one day for water quenched wheelweights to harden. If you test earlier than this you will get a low reading. You should be from 24-27, depending upon how close you came to the optimum temperature in the oven. Running things to the razor's edge as far as I could on temperature has gained me up to 33 BHN, but I was pushing things as close to the slump temperature of lead as I could go.

The Lee hardness tester should be okay-try it again after waiting for the bullets to harden.

Make sure the oven is fully up to temp before you put the bullets in. It may be that the heat treat temperature was not as high as you thought. Heating the oven five minutes then dumping the bullets in won't do it. To get hardnesses over about 27-28 required longer soaking in the oven than 30 minutes for me. This was so the oven could slowly approach the optimum temperature, and it takes time. Trying to do it fast doesn't work.

[milkman]

You guys got more smarts than a peach tree switch !! Checked the boolits this morning and they had hardened to over 20. 12.4 to 20.sumthin. I never wooda thunk it. Now, if I can just find some time to load a few.

Thanks for the assist.
Milkman

[C1PNR]

Now you're cooking! Hope you got a bunch of them sized before they got so danged hard!8)

[BOOM BOOM]

Hi,
Put them in the frezzer to slow the harding process down.

[milkman]

C1PNR, I need them as-cast diameter, so I lapped the sizer till it just kisses the driving bands and still seats the gas check. Thats one nice thing about a Lee sizer, you can't waste a whole lot of money even if you mess it up.
milkman