Answer
In the production of wave springs, 'Stress Relieving' is a low-temperature thermal treatment used after coiling to stabilize dimensions and reduce internal stresses induced by cold working. For $302/316$ stainless steel, this typically occurs at $600^{∘}F$ to $750^{∘}F$. It increases the elastic limit without significantly changing the hardness. 'Full Annealing' involves heating the material above its critical temperature ($>1900^{∘}F$) to create a fully austenitic structure, which completely softens the material. Annealing is never used after the spring is formed because it would destroy the spring tempered properties. Designers must specify stress relief to prevent 'creep' or 'set' during the first several cycles of the spring's operation in the field.
