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Vol.9, No1, 2009,
pp. 3-8 |
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ELECTROCHEMICAL HYDROGEN ABSORPTION OF API X52 STEEL AND ITS EFFECT ON LOCAL FRACTURE EMANATING FROM NOTCHES Julien Capelle, Guy Pluvinage 1 Igor Dmytrakh 2 1 Ecole Nationale d’Ingénieurs de Metz et Université Paul Verlaine Metz, France 2 Karpenko Physico-Mechanical Institute of National Academy of Sciences of Ukraine |
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Abstract The study of hydrogen-charging process of pipeline steels API X52 grade was performed and local strength of notched samples in presence of hydrogen was determined. The obtained results have shown that this steel is sensitive to hydrogenating in deoxygenated NS4 solution of near-neutral pH value. Applied stress, equal to hoop stress in pipe wall under operating internal pressure 70 bar, significantly accelerates hydrogen charging of steel and hydrogen concentration in loaded steel can be even five times higher than in unloaded steel. It was found that critical hydrogen concentration exists that causes significant reduction of steel local fracture resistance. This value might be applied as an important engineering parameter for reliability assessment of pipelines in exploitation. For local strength assessment of notched samples in presence of hydrogen the diagram “work at local fracture – hydrogen concentration” is convenient and can be accepted as basic curve for considered system “material – environment”. Keywords: hydrogen charging, hydrogen absorption, hydrogen concentration, cathodic polarisation, current density, acoustic emission, static load, work at local fracture |
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full article (665 kB)
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