Discussion in 'Metals' started by 72square, Dec 17, 2017.
I'm making brass flowers for Xmas gifts. Does yellow brass work harden?
I'm reasonably sure all brass will work harden (in fact I think all metals will work harden if my understanding is correct). You can always re-anneal as you go though, it's simple to do for brass.
that's what I thought. I couldn't find much info on the interwebs. Thanks.
yep sure will. different brass hardens a little less than others but regular 360 brass will work harden. a little heat from a propane torch and then allow to cool slowly and soft and nice to work with again. just like copper or aluminum.
neat trick on aluminum - off topic I know, but soot it up with your accetalene tocrch burning rich, once black, turn up the oxygen and heat until the soot burns back off, its annealed and ready to be worked again. -that's sheet metal aluminum I'm referring to. not bar stock or thick stuff
Brass not only work hardens, but age hardens itself as well.
It is better to leave the softening process until you are about to start work on the item as if you leave it any time, it will need re-softening again anyway.
I was always under the impression that to anneal brass and copper
you heated and then quenched in cold water. Please dont tell me
that all these these years i have been working under a misconception i
Remember at night school many,many years ago learning about age and work hardening with alum alloys in the aircraft industry and how rivets were kept in
a refrigerator and a limited time allowed to use them under strict control
conditions.Feel free to add to this as i have forgotten more than
i can remember.Bucket is full you see
I believe with copper it doesn't matter a lot if you quench it or not, you're still going to get a good anneal on it. I guess with the high copper content of brass it's similar. It's my understanding that for more difficult to anneal metals, such as stainless, proper quenching is vital.
ok, so here is my understanding, and I am probably wrong as I don't have formal training.
but think of quenching kind of like what you do in forging steel. heat it real hot and then dunk in oil or water to make it hard as you can for a blade. supposedly on steel it holds the molecules in the perfect crystalline structure - this is why carbon is important in steel so that the carbon atoms or molecules (fancy words that I'm not sure which is which) can get inside the steel molecules when they expand, then when cooled very quickly they get trapped inside that molecule and make it hard. slowly cooling allows the carbon to get pushed back out.
I guess since brass and copper isn't the same as steel and I guess we aren't putting carbon into the mix then it probably doesn't matter. just to me I treat everything as possibly hardening when queunched rapidly.
probably a better example as to why in my head quenching = hardening is drill rod, when using drill rod o-1 for example you heat glowing hot and dunk in used motor oil, it then is really hard and may even be hard enough to shatter or crack. then to anneal the outer skin to prevent the cracking but still retain strength you bake it in the oven or use the draw to straw color (or other colors for different applications) to soften the outer skin. the different colors usually the darker you draw to is softer and softer. I use straw in my example as that was the first thing I ever learned when color annealing when learning to make flat blade screw drivers.
Just get the brass very hot with a torch and then dump into cold water to soften it ! Same applies to most non ferrous metals.
But as John (Blogwitch) points out brass not only work hardens but also hardens with age.
Thanks Baron,thats my understanding of it.I always remember that
brass and copper were the exact opposite of steel
Heat and quench hardens steel and anneals brass and copper
needs to be repeated often after working and over long periods of time
Thank you for your input werewolf i remember at nightschool about
martensite ,ferite and austenitic steels and alignment of iron molecules
all too technical for me then and certainly is now. All i can still remember
is mild steel is nom 0.02% carbon and drill rod about 0.5 and above for
hardening.Cast iron can be up to 5% carbon which is burned off to produce steel.All thanks to Mr Bessemer.Pity i cant remember what i did yesterday
I think (and equally could be entirely wrong here) but the difference is the temperatures between various metals. Putting too much heat into a steel, above curie temp, and you're into the hardening range where properties are changing rapidly. Once you have the properties you're after you rapidly cool it to lock those properties in. Putting just enough heat is providing energy for the molecules to start nicely aligning and increasing the malleability of the metal, which is annealing (I think of it sort of like 'untangling the threads' of the material so it's easy to bend). Again, when the required properties are obtained we can quench the material and 'set' those properties. As I said, I think this is the case for most metals but there's bound to be other properties to consider for different metals.
When annealing brass/copper, its the heat that matters, all the quenching does is let you get back to work faster. It does not matter when annealing brass/copper if you quench or just let it air cool.
Finally, Crueby got it right!
Although it makes no difference if you quench or not. I find it better to quench the brass or copper into a mild pickling solution as it cleans the oxide from the job . More important when flanging as it saves the oxide becoming embedded into the metal when bashing it over formers. Once the brass or copper is clean for decorative work you can get some nice colouring effects using a torch
just my two pennies worth
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