Question Regarding Hardness VS Time.

[Larry D.]

I've been reading a lot looking for an answer.
We know that castings will get harder if we water quench. We also know that castings will get harder with age.
What, if any, changes in hardness will occur to aged/quenched castings are re-melted and re-cast?

[Vorga]

I asked the same question a few weeks ago and if I am wrong someone correct me . The answer I was given was water quenching hardens the casting by cooling the casting fast and then the casting hardens mostly after a week and then hardens just a little more the next week or two after that. They stay that way for about 1yr then they starts to soften again . If you then resmelt the castings you start the process all over with the hardness you started with .

[runfiverun]

they stay hard for more like 20 years.
454 found some 30 year old water dropped castings and they were still at 18 bhn.
anyway as soon as you melt down water quenched alloys they go back to the bhn of whatever the alloy is.
if you water drop them again they will go to the water dropped bhn, you cannot compound the affect.

[cbrick]

Age softening is a slower process than many think. I had oven heat treated some RCBS 35 200 to 30 BHN, 10 years later I found them stashed away and they were still 26 BHN.

The percentage of Sb will determine how fast they reach final BHN after quenching, the percentage of Sn will determine how fast they age soften. Too much tin can also limit how hard a Pb/Sb/Sn alloy will get from quenching.

Rick

[Larry D.]

Thanks for the info, guys.
I wanted to play around with an idea or two and I was hoping to be able to recover any mistakes.