@inproceedings{01HCJ567GJN11D3D4KH895NQTA,
  abstract     = {{The use of niobium as micro-alloying element in high strength OCTG (Oil Country Tubular Goods)
steel has a significant influence on the SSC (Sulphide Stress Cracking) resistance. Niobium addition
will influence the microstructure, introducing finer grains and small precipitates which can act as Htrapping sites.
In this study, two tempered martensitic materials, one without Nb and one with 0.029w% of Nb, were
placed into a cell containing and aqueous solution with 0.5w% acetic acid and 5w% NaCl, saturated
with H2S at room temperature. The samples were left under these conditions for 3, 7, 14, 21 and 28 days.
As a function of time, the corrosion surface layers and their evolution were investigated, using EPMA,
XRD and XPS, and the influence of the corrosion products on the hydrogen uptake inside the material
was evaluated using hot/melt extraction.
A clear difference in corrosion product formation was observed between the two materials. The addition
of Nb to the base metal caused a significant reduction in the amount of FeS corrosion products present
after the test. This was due to the formation of a much thicker Cr2FeO4 layer between the base material
and the FeS corrosion products. This layer was brittle, had a lot of vertical cracks over the whole
thickness, was not very adherent and caused the FeS to spall of the surface more easily.
The lack of a thick layer of FeS corrosion product on most of the metal surface caused the corrosion,
and as such the hydrogen production, to take place close to the metal surface. As such, after the material
was saturated, no drop in the diffusible hydrogen content was observed as was the case for the Mo
containing material.
In summary, the niobium addition had a positive effect on the corrosion rate and the initial amount of
diffusible hydrogen. However, on the long term, the amount of hydrogen in the material remains at a
constant high value and no decrease was observed, as was the case for the material without Nb. As such,
although the corrosion was slower for the Nb containing material, hydrogen embrittlement could be
more problematic.}},
  author       = {{Wallaert, Elien and Verbeken, Kim and Depover, Tom}},
  booktitle    = {{EUROCORR 2023, European Corrosion Congress, Proceedings}},
  language     = {{eng}},
  location     = {{Brussels, Belgium}},
  pages        = {{5}},
  title        = {{Investigation of the influence of Nb addition on the corrosion product formation and hydrogen uptake of tempered martensitic steel in H2S environment}},
  url          = {{https://www.eurocorr2023.org/}},
  year         = {{2023}},
}