Official Answer
Answer
Type 316 Stainless Steel is used when superior corrosion resistance to chlorides (seawater) is required, due to its 2-3% Molybdenum content. However, 316 cannot be hardened by heat treatment; it only gains strength through cold working. Consequently, a 316 spiral ring will have a lower thrust capacity and lower 'cling' force than a 17-7PH ring of the same dimensions. Designers must often use a heavier cross-section to achieve the required mechanical performance. In subsea instrumentation, 316 is often the minimum requirement, though for high-pressure housings, alloys like Monel K-500 or Inconel 718 may be substituted if the stress levels exceed 316's limits.
