Effect of Chromium Oxide Film Formation, Mainly by the INCO Method, on Hydrogen Permeability on Welded Type 304 Stainless Steel

Abstract

This study assessed surface treatment techniques applicable to welded joints of stainless steel pipes and vessels for a hydrogen-permeation barrier. Specifically investigated was electrolytic polishing using electrolyte compositions consisting of sulfuric acid, phosphoric acid, and methane-sulfonic acid to promote uniform passive film formation on a type 304 stainless steel surface. This study also examined oxidation treatment using a combination of chemical oxidation, cathodic electrolysis, and passivation. Hydrogen gas permeation suppression was confirmed for welded SUS304 steel substrates treated under selected conditions suitable for thickening, homogenizing, and densifying passivation films.