The resistance to hydrogen embrittlement has been investigated for two of the most common duplex stainless steels, UNS S31803 and UNS S32750. The test environment was set up to simulate the influence of cathodic protection in seawater with the test solution as synthetic seawater at 80°C. As a substitute for cathodic protection, zinc was coupled to samples. In addition, the samples were electrochemically pre-charged with hydrogen. Both annealed and 20% cold worked material were tested using a constant load test at 90% of tensile strength. Cold worked material was also tested with the slow
strain rate technique. This investigation indicates that there is a very low risk of hydrogen embrittlement for these duplex steels in seawater when cathodically protected with a potential corresponding to Zn. However, for cold worked UNS S32750, plastic straining during service may cause hydrogen embrittlement. The test indicates that the risk is lower for UNS S31803.
Keyword: hydrogen embrittlement, duplex stainless steels, cathodic protection, cold work