TY  - JOUR
PY  - 2021//
TI  - Assessment of operational degradation of pipeline steels
JO  - Materials (Basel, Switzerland)
A1  - Nykyforchyn, Hryhoriy
A1  - Zvirko, Olha
A1  - Dzioba, Ihor
A1  - Krechkovska, Halyna
A1  - Hredil, Myroslava
A1  - Tsyrulnyk, Oleksandr
A1  - Student, Oleksandra
A1  - Lipiec, Sebastian
A1  - Pala, Robert
SP  - e3247
EP  - e3247
VL  - 14
IS  - 12
N2  - This paper summarizes a series of the authors research in the field of assessing the operational degradation of oil and gas transit pipeline steels. Both mechanical and electrochemical properties of steels are deteriorated after operation, as is their resistance to environmentally-assisted cracking. The characteristics of resistance to brittle fracture and stress corrosion cracking decrease most intensively, which is associated with a development of in-bulk dissipated microdamages of the material. The most sensitive indicators of changes in the materials state caused by degradation are impact toughness and fracture toughness by the J-integral method. The degradation degree of pipeline steels can also be evaluated nondestructively based on in-service changes in their polarization resistance and potential of the fracture surface. Attention is drawn to hydrogenation of a pipe wall from inside as a result of the electrochemical interaction of pipe metal with condensed moisture, which facilitates operational degradation of steel due to the combined action of operating stresses and hydrogen. The development of microdamages along steel texture was evidenced metallographically as a trend to the selective etching of boundaries between adjacent bands of ferrite and pearlite and fractographically by revealing brittle fracture elements on the fracture surfaces, namely delamination and cleavage, indicating the sites of cohesion weakening between ferrite and pearlite bands. The state of the X52 steel in its initial state and after use for 30 years was assessed based on the numerical simulation method. 2021 by the authors.     Keywords: Pipeline transportation.<p />  <p>Language: en</p>
LA  - en
SN  - 1996-1944
UR  - http://dx.doi.org/10.3390/ma14123247
ID  - ref1
ER  -