This paper describes a programme of work set upto investigate the susceptibility of super duplex stainless steelsto hydrogen embrittlement under cathodically polarisedconditions. Constant load tensile tests have shown that althoughthe material is susceptible to embrittlement, failure only occursat high stress levels. This behaviour can be attributed to thepresence of the austenitic phase which restricts the growth ofhydrogen induced cleavage cracks through the ferrite. Howeverunder cyclic loading the austenite ligaments fail and hydrogenenhanced crack growth can then progress. As a result fatiguecrack propagation rates are markedly higher under cathodicpolarisation. This highlights the importance of using suitabletest techniques when making an assessment of this phenomenon.
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