Hydrogen embrittlement under cathodic protection of friction stir welded UNS S32760 super duplex stainless steel

摘要

Hydrogen Induced Stress Cracking (HISC) resistance of super duplex stainless steels is basically controlled by the material's microstructure. Friction stir welding is a low heat input joining process that has the potential to maintain the base metal original resistance to HISC since it does not significantly alter the proportion of ferrite and austenite. This work evaluated the susceptibility to HISC under cathodic protection of friction stir welded super duplex stainless steel UNS S32760. Microstructure evaluation revealed a recommended proportion of ferrite and austenite phases as well a refinement of the overall stir zone microstructure. Fracture toughness tests in synthetic sea water under cathodic protection of - 895 mV_(sce) indicated that the microstructure of the stir zone is actually less sensitive to HISC than the microstructure of the base metal.