Assessment of Steel Sensitivity to Hydrogen Induced Cracking

Factors influencing hydrogen induced cracking of transmission pipelinesteels are described in the paper. Ratios of hydrogen induced cracking are presented,determined on the basis of metallographic examination, as well as the new hydrogeninduced cracking ratio determined on the basis of a static tensile test. A model allowing foran assessment of specimens behaviour with hydrogen induced cracks has been proposed.This model allows to determine the relations between the HIC ratios proposed by NACETMO 284-96 Standard (metallographic examinations) and the new HIC ratio proposed byauthors which expresses the decrease of the plastic properties (contraction) ofhydrogenated specimens in relation to non-hydrogenated specimens (strength tests). Thepresented model has been verified basing on the results of HIC tests of X52, X60, X65, X70steels.