Depending on the amount of carbon content in a material it would take heating the material to 50 degrees above the critical temp (the temp were changes in the microstructure of the steel take place) to fully anneal the material, so no boiling traps will not hurt your springs. Just for reference I heat treat S-7 tool steel at 1735 degrees.

The issue at hand has much more to do with physics than trapping. And the physics involved is not much more complicated than high school general science.

But look at it this way if you have any metal pan containing water and you apply heat to the bottom, with something less than an oxy-acetylene torch, can you melt, soften or damage the pan? No. Can you heat water significantly above the boiling point at sea level in an open container, even with an oxy-acetylene torch? No. You simply cannot take the temper out of a spring immersed in boiling water. And I'll add whether it is touching the bottom or not.

The more heat you apply the faster the water turns from 100 degree liquid to 100 degree steam…you get more bubbles. You cannot significantly raise the temperature above boiling until the last liquid water is turned to steam or you contain the steam water and increase the pressure. It really is just that simple.

Oh and its going to be a cold winter I saw a wolly worm today and his black was wider than his orange or was it the other way around?

Dated for search.