Respirometry, a new approach for investigation of the relationship between corrosion-induced hydrogen evolution and its entry into metallic materials.

Cathodic processes in initial stages of atmospheric corrosion of rolled zinc and bare, Al–Si and Zn–Fe coated press hardened steel were studied. A ratio between hydrogen evolution and oxygen reduction reactions was evaluated using the manometric respirometry technique. Hydrogen evolution reaction proceeded on all studied materials, providing from 7 to 27 % of the cathodic current. The content of diffusible hydrogen in steel was low indicating that hydrogen recombination was highly efficient and only a minor part of produced hydrogen absorbed into the materials. The efficiency of hydrogen recombination is thus expected to control the hydrogen entry process. • Respirometry is suitable for studies of cathodic processes in atmospheric corrosion. • Hydrogen evolution reaction proceeded on all studied materials. • Only low amounts of diffusible hydrogen found in steel structure. • Hydrogen recombination is significantly more efficient compared to absorption. • Hydrogen formation on zinc enhanced in CO 2 -free atmosphere. [ABSTRACT FROM AUTHOR]