Hydrogen embrittlement of a low carbon steel during slow strain testing in chloride solutions containing sulphate reducing bacteria

The paper presents results of a laboratory investigation of the microbiological environment assisted stress corrosion cracking of carbon steel in chloride solutions. Carbon steel specimens were subjected to slow strain rate testing (SSRT) in an aqueous solution of 3.5% sodium chloride, with and without a microbiological culture. Specimens tested in the biotic (microbiological) conditions showed a considerable loss of ductility, as compared to those tested in abiotic conditions. Fractography of the specimens tested in abiotic solutions suggested features of only ductile failure (dimples), whereas those tested in biotic conditions also had features of brittle cracking. Results of SSRT tests of the specimens pre-subjected to the electrochemical conditions for hydrogen charging have indicated susceptibility of the steel to hydrogen assisted cracking, and therefore suggesting a role of microbial environment in promoting hydrogen assisted cracking.