Looking for stress relieving advice

MrWhoopee said:
Being a woodburner myself, I really like this.:eagerness: It should give you a full anneal without risking the wife getting out of sorts. Of course it won't fly in the summer.
Click to expand...

Use a camp fire!

Ted
 
I put a couple of old blunt files into the woodburner hoping to anneal them somewhat, so to use the metal for another purpose. I think it sort of worked because I can now file on the metal with another file.
BUT..
.. it begs the question as to whether "stress relieving" need be the same thing as "annealing"?

I get it that if you heat the metal fully to annealing temperature, then cool slowly, then you will definitely have relieved stresses, but can being cooked at a temperature well short of annealing also relieve stresses?

I ask because we know that you can temper fully quenched near glass-hard steel back to less hard, yet not brittle, using temperatures much lower than getting it to red heat. The internals of the metal structure clearly can be altered by much lower temperatures, possibly like those easily achieved in a domestic oven.

If you do use a woodburner, make sure there is a nice layer of wood ash under the part, and before the overnight cool-down, cover it with hot wood coals and ash. The ash is such a good insulator, I have raked apparently cold ashes aside in the morning, and found coals in them still glowing red!
 
graham-xrf said:
I put a couple of old blunt files into the woodburner hoping to anneal them somewhat, so to use the metal for another purpose. I think it sort of worked because I can now file on the metal with another file.
BUT..
.. it begs the question as to whether "stress relieving" need be the same thing as "annealing"?

I get it that if you heat the metal fully to annealing temperature, then cool slowly, then you will definitely have relieved stresses, but can being cooked at a temperature well short of annealing also relieve stresses?

I ask because we know that you can temper fully quenched near glass-hard steel back to less hard, yet not brittle, using temperatures much lower than getting it to red heat. The internals of the metal structure clearly can be altered by much lower temperatures, possibly like those easily achieved in a domestic oven.
Click to expand...
They are not the same.

Annealing is heating and holding above the critical temperature (between 1330 and 1670° F, depending on the alloy), then slowly cooling, resulting in the softest condition of the steel.

Annealing / Normalising - Heat Treatment - Bodycote plc

Annealing is a heat treatment process which alters the microstructure of a material to change its mechanical or electrical properties. Typically, in steels, annealing is used to reduce hardness, increase ductility and help eliminate internal stresses.
www.bodycote.com www.bodycote.com

Stress-relieving is heating to a temperature below the critical temperature (between 1000 and 1200°F) which allows internal stresses to relax without reducing the hardness of the steel.

Stress relieving on metal products - Heat treatment - Bodycote Plc

Minimising residual stresses in the component structure thereby reduces the risk of dimensional changes during further manufacturing or final use of the component.
www.bodycote.com www.bodycote.com
 
Full stress relief will reduce the yield stress for anything that was hardened or cold worked. Once you have hardened and tempered running up to or near the tempering temperature will generally not do anything.

However, precipitation hardened materials like many Aluminum alloys and 17-4PH also have a time at temperature dependence below the dissolving temperature.

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Well, this is just a sine bar. I don't expect it to carry any loads. I just want it to stay the same dimensions that I cut it at.

Just cause it was easy, and I was in the shop anyway, I threw it in the toaster oven today. It turned a bright, irridescent blue. Quite pretty actually. I don't know if that give any clue as to what the composition of the material is, though.
 
Don't know if this link will come through, but it is the only graph I could find that would plot temperature against the amount of stress relief that could be achieved. It looks like leaving it in the oven longer will help, but the toaster over is only going to do the barest amount of stress relieving.


Just more justification for me to get this furnace build finished up.
 
Interesting data! Any idea where it came from?

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