Precipitation-hardened stainless steels, used as bolting material such as UNS S66286 (Grade 660D), are listed in standards including API Specification 6A and NORSOK M-001 as alternatives to nickel-based alloys. Their application in subsea production environments is currently limited by ISO 15156 to 66 °C (150 °F), although previous studies suggest the material may withstand higher operating temperatures. In addition to temperature, other relevant parameters for evaluating environmentally assisted cracking behavior include pH, chloride concentration, and the partial pressure of H₂S. To assess the material's performance in high-chloride environments, a combination of electrochemical tests and slow strain rate tests has been conducted. Furthermore, a brief discussion on stress corrosion crack (SCC) testing methodology is presented.
