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tannin concentration of 1.0 g/dm . It has been found that the inhibitor blocks freshly
formed surfaces, inhibiting their anodic dissolution, at the stage of crack initiation
and inhibits hydrogenation at the stage of crack growth.
A method for predicting the effectiveness of inhibitory protection of ferritic-
pearlite steels of sucker rods against corrosion-fatigue failure in formation water has
been developed. The method is based on the established correlation between
electrochemical (amount of electricity spent for metal oxidation of freshly formed
surface at corrosion potential) and corrosion-mechanical (corrosion-fatigue crack
initiation period) indicators.
The influence of operation conditions and hydrogenation on the anisotropy of
characteristics of strength, plasticity, impact toughness, resistance to hydrogen
embrittlement and fracture toughness of rolled pipeline steels depending on the
orientation of the plane of fracture propagation in axial, tangential and radial
directions have been assessed. It has been demonstrated that hydrogenation of long-
term operated rolled ferritic-pearlitic pipeline steels significantly enhances the
anisotropy of their mechanical properties, especially plasticity, impact toughness,
resistance to hydrogen embrittlement and fracture toughness, due to
microdelaminating between fibres and in the vicinity of non-metallic inclusions
along rolling direction and fracture of membranes between them by transgranular
chipping. It has been established that the tensile deformation energy of the
hydrogenated specimen with a crack before its start in the direction between the
fibres is 60 times less than across the fibres.
Scientific novelty of the obtained results.
It has been established that structural-free ferrite mostly dissolves at the initial
stage of corrosion of the ferritic-pearlitic 50Г and 32Г2 steels in 1% NaCl solution
with pH = 3.1 and CO 2 bubbling into the solution, which simulates formation
waters; the fraction of structural-free ferrite in the steel microstructure is the
dominant factor of corrosion intensification.
The influence of microstructure of ferritic-pearlitic steels of casing pipes with
different strength on resistance to hydrogen embrittlement has been defined: the 32Г2