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Effect of temperature on springs

If you stay below the tempering temperature you should have no problem. Most springs are tempered at a much higher temp than that. If you wind a new spring from music wire it is recommended to stress relieve it at 375F. You should be OK.

Ed.
 
If you stay below the tempering temperature you should have no problem. Most springs are tempered at a much higher temp than that. If you wind a new spring from music wire it is recommended to stress relieve it at 375F. You should be OK.

Ed.

Very true. I did some tests on springs that were both compressed and extended in service. Before stress relieving, they would not return to center after being extended or compressed. The explanation is that winding the spring requires that you exceed the yield point to make the spring take the new shape. After winding, some parts of the spring will be near yield and will pass it when they are flexed so it will take a set. After baking, they performed exactly as the table said they would.

You can Google tables for any alloy. It does vary greatly.

Relieving will also greatly improve the fatigue life.

Bill
 
probably some sort of paint baking process involves that temperature, and he is wondering if he'll loose temper in the spring, I can't imagine any other reason any springs in that rifle would be subject to such temperature

and automotive springs under normal circumstances never reach such temperatures...
 
what specifically are you trying to do to it?

I'm going to paint it camo. After paint, it needs to be baked. Since the paint job will be camo, I'm going to paint it assembled so that the camo pattern matches across parts. It would be simpler just to leave it together and throw it in the oven. If necessary, however, I could disassemble it to remove the springs before baking. Baking needs to be between 325° and 350° F for at least 60 minutes.
 
Will 350° F for one hour have any impact on springs? (Specifically, the springs used in an AR-15.)

Can’t answer your question directly. Only way to answer for certain is to know the original tempering temperature of the spring. If you stay below that there is no significant drop in hardness. I’ll go with the consensus here and say no problem as the original temper is most likely 375-400F.
 
Assuming that 350 is OK and 375 is not, next step is to make sure whatever heating device you are using is capable of holding the proper temperature. A consumer grade oven has a wiiiiide band around the setpoint that it will tolerate.
 
I was wondering if valve springs got up to 350° F. Sounded hot to me.

Yeah, I could see it, or more. The coolant system's running around 220F, oil will be a bit higher, and remember there's internal heating in the spring from the deflection/extension of the material.

On a racing engine I'd bet they go over 400F after prolonged periods.

[After I wrote the above, went and searched: valve spring temperature - Don Terrill’s Speed-Talk so my guess it pretty good...]
 
Remove the springs then reassemble before painting, bake, replace the springs.

Thank you,
Mr.Smith
 
If you're worried about it that much, make them out of Inconel X750. Good for around 800 degrees before you have to worry about derating or taking a set.
 








 
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