Official Answer
Answer
Spiral rings are typically made from cold-rolled tempered carbon steel. The 'clinging' force, which keeps the ring seated in the groove, is a function of the ring's installed tension. If the ring is over-tempered (too soft), it will undergo plastic deformation during installation, losing its 'memory' and failing to cling tightly. If it is under-tempered (too hard), it becomes brittle and may crack during the expansion required to slip it over a shaft. The target hardness is usually 45-52 HRC. This balance ensures the ring can expand by $10-15\%$ of its diameter during installation and return to its original size for a tight fit.
