Why low BHN from COWW's ?

[RogerDat]

Some COWW lead that was recently cast had a BHN of only around 9. I would expect something along the lines of 12 or thereabouts.
I know the material was all COWW's so why would they run to the softer side like that?

[scottfire1957]

Because the manufacturer used a different alloy. More lead, less other stuff. Easy peasy. Get your sample analyzed, it's the ONLY way to be sure that the alloy is to blame.

Otherwise, it's something you did.

Edit: that could range from temerature problems to equipment malfunction/misuse/misreading etc. etc.

Ocham's razor says alloy change.

[Yodogsandman]

Is that BHN measurement taken right away or after a few weeks of age hardening? I wonder if the heat of summer slows the age hardening process a little.

[country gent]

wheel weights do vary some from when manufactured and also from the manufacturer. Lead is the cheap part of the mixture so some may be scrimping on antimony and tin in the mix. Another variable mentioned above is temp and technique. Sometimes tin and antimony can be removed thru temps and fluxing. On the plus side once cleaned up and known it is a simple matter to blend what you want.

[pjames32]

My COWW have a much lower bhn now that 20-40 years ago. YMMV
PJ

[bhn22]

Wheelweights are now made with scrap metals, with little regard for the quality or composition of the alloys.

[John Boy]

Some COWW lead that was recently cast had a BHN of only around 9. As was mentioned, your Bhn hardness will get harder after it has been aged - possibly in the Bhn 12 range

[LAGS]

Years ago when I managed a Tire store, I would save the COWW for my casting.
They were a consistant 10 right after smelting.
But a few years later, the weights got softer, and I started seperating the hard ones from the soft ones.
The soft ones barely came up to a 9 even after they aged, the hard ones came up to an 11 but a little higher if water dropped.
So if you have mostly soft weights now, and even some hard ones mixed in , the average I have seen just smelted all together is a 10 on average, and maybe a 12 after about 2% tin is added for castability.
My sugestion is to Seperate and test the hardness with wire cutters and smelt seperatly.
And do not throw in SOWW , Smelt them totally seperate.

[lightman]

i've found wheelweights to be pretty consistent. I've also found that newer coww are a softer alloy than 20 or 30 yr old ones. I think I posted about melting a batch of newer weights recently that went 12 or 13 bnh. I'm not sure how to explain your bnh. It looks like wheelweights may not be our best friend much longer!

[farmerjim]

50 years ago when I started casting, we had to buy pure lead at $0.30 per pound to mix 50/50 with the $0.05 per pound ww. I have some of the ingots from the old ww's and they tested 22 bhn. I think the new ones can be anything.

[RogerDat]

I do sort and smelt SOWW's separate. I nip all the WW's with dikes to confirm they are lead. Have noticed some COWW's are a modest but noticeable amount harder/softer. Had not considered sorting them by that difference.

Had not taken them in to have them gunned to find out the composition either. They be COWW's and in my scrap scrounging world that qualified them as a "known" alloy. May have to take a representative sample into the scrap yard to test. Come to think of it I did use them to make some Lyman #2 and did have that gunned, came out about .17 - .23 lower on antimony from what I was expecting. Not a lot but.... I figured the linotype, solder portions or alloy percentages were off by a bit, which they could have been, was a touch higher on tin than expected also.