Does copper age harden?

Copper tubing to be exact. I have a couple rolled lengths of soft
copper tube. One length is about 20 years old and the other about 4
years old. Both are the soft copper tubing commonly used for
refrigeration or water. It comes with a plastic cap on each end.
Anyway, my old rolled length, which I discovered the other day when
cleaning out some junk, is much stiffer than the new roll. So I am
wondering if the copper got stiffer over time because the older stuff
is quite a bit harder to bend than the newer stuff.
Eric
Reply to
etpm
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You sure it isn't just K or L over M, maybe? I've no reason to think it will harden just with age; I've pieces around that are at least 50 or 60 yo that I use chunks off of periodically and never noticed any real difference.
Reply to
dpb
Except for certain alloys it doesn't age harden. But refer tube has a pretty wide tolerance in wall thickness. Typically +-10% of the thickness. My guess is that when copper was cheaper, they erred on the plus side, now they lean to the minus.
One could as much as 20% thicker than the other.
Paul K. Dickman
Reply to
Paul K. Dickman
Maybe that's it, different types. I thought all the coiled copper tubing for refrigeration was the same. Thanks. Eric
Reply to
etpm
Greetings Paul, I can check that. I just checked, both coils have the same wall thickness and O.D. I think it must just be different types of copper tube. Eric
Reply to
etpm
More likely it's different degrees of annealing. Copper readily work hardens, and the soft type has to be thoroughly annealed so it will freely bend.
Heat treating isn't always consistent.
Reply to
Ed Huntress
I think the only difference re: the HVAC line-specific line is it is specially cleaned/produced to minimize any oil contaminants. AFAIK wall thicknesses are K and L (no M, the cheapie box store variant usually found) but that's still enough between the two to make a noticeable difference in stiffness. I suppose there could be some difference in an alloy between manufacturers, too, not sure how much variation there might be in that regard.
Reply to
dpb
OK, _now_ I see that you have measured wall thickness; I concur on likely treating differences is the difference...
Reply to
dpb
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"Soft copper tubing has a tendency to harden as a result of vibration, oxidation, and bending. This is called work-hardening."
-jsw
Reply to
Jim Wilkins

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