An investigation was conducted on prematurely failed titanium stabilised austenitic stainless steel tubes of a heat exchanger used in sea water service. The tubes were longitudinally welded using the high frequency electric resistance welding technique. The investigation showed the failure to be due to pitting and crevice corrosion at the weld. The attack occurred at discrete sites and the deposits inside the pits were rich in chromium and iron. The corrosion of the tubes was attributed to depletion of chromium and molybdenum from the austenite phase. This depletion was ascribed to coarsening of the delta ferrite phase as a result of high heat input during welding.
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