Technical Annealing question

I know (or think I know) that copper can be annealed (softened) by heating red then quenching in cold water. My question is- can brass heater cores or radiators be annealed by the same process? I am looking to put an old Monkey Wards heater in my '46 Chevy PU project that I found on ebay, but the tubes are deformed. I want to straighten the tubes to dis-assemble the heater and fit it through the firewall. I thought I would immerse the core in cold water up to the part that needs to be straightened so it wouldn't melt the solder, (after removing the fan motor) then dunk the whole thing deeper in a tub of water after heating. Any of you guys do radiator repair or have any thoughts on this?

 

I've got an old Montgomery Ward heater in my Model A. I was able to straighten the tubes cold. I used some round bar the correct diameter and a body hammer. I also made a little tool to put the hump in the tube so the hose won't slip off.

 

I would think that heating it up and straightening it would suffice, just let it cool on its own

 

The annealing (soften) process involves heating up a metal, then let that metal cool down to room temperature on its own, without a quench in water or any other substance.

If you heat metal, then dip it in a cool liquid, that will harden the metal.

Do not cool it down quickly if you want the metal to be soft.

 

What you say is true for ferrous metals, however copper and aluminum alloys do require a quench. Annealing and quenching are vague terms that describe many processes for many materials. Quenching in air may be adequate, while water is likely to perform better in some materials. Copper alloys get extremely brittle at elevated temperatures, best to bend cold

 

I'll agree with doing it cold. I tried to make an adaptor for an engine swap on an OT car and decided to braze it so I could powdercoat it. The copper was so soft after that that the radiator hose clamp collapsed the tube when I tightened it.

 

I agree with your plan. Old copper can be brittle and annealing it will help. As long as all the solder joints are kept under water it should be fine.

 

From what I know & have read about annealing brass for firearms, you stand up the brass cartridge case in a pan with just the upper 3/8" to 1/2" of the case above the water line. You then slowly heat the part above the water line to a dull red & then let it slowly cool on its own. To do this to your heater core hose ends, I believe that you would have to remove the core and submerge all but about 1" to 1 & 1/2" of the hose ends & do the same. I would use a propane torch as an oxy/accet torch would be too hot & hard to control heating the thin hose ends & possibly melt them.

 

To heat it hot enough to anneal the copper and then reshape the pipe you may damaging the core. A better option may be to cut the original pipes near the core as and carefully solder in new copper pipe using an inline connector.

 

Or swage the end of a piece of copper tube to go over the stubs from the core.

 

I recall the Jesse James show (forget the name) where he “annealed” aluminum, he did it to soften it up I guess to dem a gas tank for a MC, but he used a near all acetylene flame that left a soot on the material. Then wiped it off, went to work.
I always thought the low heat, soot too, is was made it soft and kept it soft.
Ofcourse this was all done on a 30/60 minute reality show, so maybe some steps not shown?

 

Not intending to be “that guy”, but having spent a career working with metallurgists, primarily with ferrous metals, they would cringe if you equated tempering with hardening. Hardening ferrous metals normally means heating the material to transform the grain structure to austenite (IIRC), then rapidly cooling (quenching) to form a martensitic grain structure. Martensite is very strong, but brittle, so the hardening process is completed by tempering, which means reheating to a lower temperature than was used before the quench, holding at that temperature for a set period of time, then slowly cooling. The tempering process refines the grain structure, giving up some hardness in exchange for “toughness,” (resistance to shock/impact loads).

 

In the past I have cut heater core tubes where needed and soldered household copper
elbows on to finish the job, I also soldered 14 gauge wire (household 14/2 wire) near
the end of the tube to make a ring so the heater hose would not slip off after being clamped.

 

Yes, to anneal alu, you soot the material, and then with a "rosebud" tip, you heat the material until the soot burns off, But its not permanent as by working the material the material again work hardens and would need to be annealed again in order to continue. Annealing was a way to hand form alu to get it to move, Machined forming alu, the machine does not care how hard the material is

 

You can anneal the copper to soften it to work it, but working it will cause it to harden again.

You can either allow the copper to cool slowly on it's own, or you can cool it faster with water. Cooling with water will soften it even more. A potential problem I see with your plan is that the tubes will remain soft after annealing, and as Crazysteve mentioned he had problems with tubing crushing after annealing it. I would anneal just where the bends are that you want to straighten, not the entire tube, then by straightening the tubes the process will cause work hardening; this is good. If you need to continue working the tubes you may need to anneal them again; you can do this repeatedly until you get the tubes the shape you need, and if you do it correctly only the portion of the tube you need to bend will be annealed, the rest will remain hard; and by bending the tube into the final shape you want you will bring back enough hardening so they keep that shape.

Here's some info on annealing copper: https://www.ehow.com/how_5796817_anneal-copper-tubing.html

Here's a cool video of a guy showing the process:

 

Thanks for all the suggestions. I too had read about annealing brass cartridges by standing in a pan of shallow water, heating and then tipping them over into the water. I've also read about (and done this myself) heating copper sealing washers and then dropping into cold water to soften for re-use. I think I'm gonna start trying to work it cold, then if it's too brittle, trying the annealing process; then if it f***s up, cutting off and soldering rigid copper tube in place of it. I also like @Von Psycho's idea of soldering on a ring of copper wire for a "dog knot"