Water dropped wheel weight BHN?

[smallshot13]

I smelted some raw wheel weights, fluxed and cast in ingots. First boolits cast and water dropped are measuring BHN 22.7 with Lee hardness tester, a big surprise as I was expecting 15-18. They were frosty, so I had the temp up, maybe above what my thermometer read, which was around 680. Is this possible, or did I somehow contaminate with zinc, or??? Oh, I did add 2oz of tin solder to the 11 lb total melt.

[beladran]

22bhn is what straight lino is.. +/-

[geargnasher]

Frosty boolits are due to a hot mould, not the alloy temperature. With wheel weights (or any similar ternary alloy) containing tin, 650-725 degrees is about right for the alloy. I like a light frost on my boolits, makes sure the mould is up to a good casting temp. If the "frost" will wipe right off with a rag leaving a shiny boolit surface, you're just fine.

Boolits cast from a cooler mould tend to be softer both air-cooled and water-quenched than boolits that fall from a very hot mold.

Most WW alloy in my experience gets from 20-24 bhn when the mould is hot enough to frost them, but keep in mind the boolits need to age harden for up to two weeks before achieving a final and stable hardness. If you check them right after casting, and again every day for two weeks, you'll see them gain a point or two each day for the first few days and then gradually taper off.

You added about the right amount of tin IMO, and it doesn't sound like you have any zinc in there.

Gear

[geargnasher]

22bhn is what straight lino is.. +/-

That's right. If you heat-treat typical clip-on WW alloy (96.5/3/.5) it can get as hard as 28, and water-quenched will often be right at what air-cooled Lino is. The difference is the hardened WW metal and Lino is the WW metal will be much more flexible while still having the same toughness, so is much better for rifle boolits in many applications than Lino is.

Gear

[smallshot13]

That's right. If you heat-treat typical clip-on WW alloy (96.5/3/.5) it can get as hard as 28, and water-quenched will often be right at what air-cooled Lino is. The difference is the hardened WW metal and Lino is the WW metal will be much more flexible while still having the same toughness, so is much better for rifle boolits in many applications than Lino is.

Gear

Thanks for the confirmation. I was beginning to worry. Along with the advice about mould temp, I think I am OK with this casting. I still may re-melt and mix with some stick-on, as I don't need BHN 22 for 45 ACP boolits.