Publikacje

Abstract:

In the research, the corrosion and mechanical properties, as well as susceptibility to hy-
drogen embrittlement, of two casing pipe steels were investigated in order to assess their servicea-
bility in corrosive and hydrogenating environments under operation in oil and gas wells. Two car-
bon steels with different microstructures were tested: the medium carbon steel (MCS) with bainitic
microstructure and the medium-high carbon steel (MHCS) with ferrite–pearlite microstructure. The
results showed that the corrosion resistance of the MHCS in CO2-containing acid chloride solution,
simulating formation water, was significantly lowe r than that of the MCS, which was associated
with microstructure features. The higher strength MCS with the dispersed microstructure was less
susceptible to hydrogen embrittlement under preliminary electrolytic hydrogenation than the lower
strength MHCS with the coarse-grained microstructure. To estimate the embrittlement of steels, the
method of the FEM load simulation of the specim ens with cracks was used. The constitutive rela-
tions of the true stress–strain of the tested steels were defined. The stress and strain dependences in
the crack tip were calculated. It was found that the MHCS was characterized by the lower plasticity
on the stage of the neck formation of the specimen and the lower fracture toughness than the other
one. The obtained results demonstrating the limitat ions of the usage of casing pipes made of the
MHCS with the coarse-grained ferrite/pearlite mi crostructure in corrosive and hydrogenating en-
vironments were discussed.

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Evaluation of Corrosion, Mechanical Properties and Hydrogen Embrittlement of Casing Pipe Steels with Different Microstructure