I have a lamp with a tank that has a lot of dents in it. Is heating the dented section before working the dent out effective/practical? I planned to use a wood "spudger" with a rounded head to push from inside the tank, but I wasn't sure if heat was appropriate, and how much heat to apply. Any pointers/experience would be appreciated.
Yes heat and beat is the way. Don't beat hot though. Heat-quench-beat always. Brass work hardens very quickly so heat frequently. ::Neil::
Brass gets "Hot short" so will be likely to crack if you heat and work. The traditional way of annealing brass is to heat and quench. I am not sure if it will anneal if it is not quenched. I suppose it will but it certainly does after quenching and anyway you want it cold to work so that is the way to go. ::Neil::
I would think air cooling brass would work as well as quenching, right? If you write on the metal with a 'Sharpie' pen, when the torch fades the writing it is annealed. I learned that in a jewelry making class. Ken in NC
not sure about that Ken it may work brass gets harder just by heating and slow cooling I think the fast cooling as in quenching is what softens the brass like neil has said. I have heated dinted areas on tanks quenched then pushed them out with a stick or bar down the filler hole on occasions Al cheers pete
Thanks Pete, that's exactly what I was thinking of doing. I'm going to try and use the end of a broom handle to push out the most egregious dent, but leave the rest as character. Al
It needs to be good and hot, red heat I think and as others have said quench. Have you got any soldered joints anywhere on the tank. You will probably melt them.
As I understand it heating and slow cooling actually tempers brass. Makes it harder and more brittle in other words. To anneal you heat and quench. It needs to be dull red hot. Have to be carefull here because as you get towards bright orange you are nearing melt point of the brass. Brass melts at around 800C. That varies depending on the ratio of zinc and copper. So you heat to around 650C. Soft solder melt is around 150c to 250C. Therefore any heating of brass in a tank which is soft solder sealed is likely to compromise the solder. You can to a certain extent control this by adding a little water to the tank so the seals are all under water. That pretty much means the solder won't heat to much over 100C. Tricky though and you may find you will need to re run the solder seal afterwards. ::Neil::
Well, tempering is to soften a too hard material, so in that aspect I guess you could call it tempering. But then you'd have to call it tempering when quenching too since this makes no practical difference to brass compared to when slowly cool it off (which is the normal procedure to soften brass). I think tempering is mainly used with ferrous alloys, right? Especially it's necessary after hardening steel. I have fiddled quite alot with that, and hardened steel is pretty useless for most purposes, but after a tempering you can get it useable in tools again. For non-ferrous materials like brass that you would soften up, it is better to be called annealing. Normal procedure is to heat it up to a certain temperature (I think it is around 500C, or thereabout, but that's better to look up first), let it sit for a certain period to reform all crystals (relieving stress). Then it usually should cool off slowly. However you can toss heated brass directly into water without it being hardened like steel would, and I think it in many ways are more practical to do so since you can start to work with the material immediately.
Odd thing this because I was taught in college that you heated and quenched brass to anneal it. Part of the course was a term on metallurgy and I never had any reason to disbelieve. However having done some digging I suspect that what was really being said was that you CAN quench to anneal rather than you have to. So there has grown the myth that quenching is required which I never had any reason to doubt. So you are right and slow cooling will do the job. Mind you the ability to quench does make working the metal quicker. There is also the consideration that some brasses will lose ductility when hot. This is called being Hot Short. Not all brass will be Hot short but since we pretty well never know the exact make up of the alloy we are dealing with it is advisable to assume the brass we are playing with will be hot short and therefore must be worked cold. To that end quenching becomes important to ensure the brass does not crack when being worked. So I guess the bottom line here is brass is annealed by heating but should not be worked hot and since quenching does not affect the annealing process it is normally heated and quenched to avoid long waiting periods between heating and working. ::Neil::
Yes, something like that is how I understand it. I have read some metallurgy too, but most are gone by now. And the school mainly concentrated on iron and ferrous alloys anyway. It sure is practical to not be forced to wait for the item to cool off slowly before working it, but just toss it in water. That's probably one reason that this "myth" has spread so widely. I'm pretty sure the tanks were made in alfa-type brass since that's the kind used for rolling, pressing etc., and that is the type that don't need any quenching. The other type - beta - would gain some benefits by being quenched, but I don't remember exactly which.
My college days were in the early 1960s and I don't remember much either. The qualification was in mechanical-production engineering but I was a civil engineer so never needed to retain much of it all. ::Neil::
Most of my college metallurgy lab work was done with brass. To harden it must be cold worked. No heat treatment can make it harder. It anneals very easily and you can use water to quench it. However you can also let it air cool, and it will also be annealed. It does not behave like any steel, including precipitation hardening stainless like 17-4ph. To harden 17-4ph you air cool. To anneal you quench. The precipitates (solid) form as it cools slowly. So the quench here deprives it of the time it takes for the hardening reaction. Hope that all makes sense. Best wishes Dan MacPherson California USA
