Abstract—Pipe steels suitable for carbon capture and storage technology (CCS) require resistance against the corrosive environment of a potential CCS-site (heat, pressure, salinity of the aquifer, CO2-partial pressure). X5CrNiCuNb16-4 has been proven to be sufficient resistant in corrosive environments, but shows rather unusual corrosion behaviour in CCS environment. Therefore differently heat treated coupons of 1.4542 were kept at T=60 °C and ambient pressure as well as p=100 bar for 700 h - 8000 h in an a) water saturated supercritical CO2 and b) CO2-saturated synthetic aquifer environment similar to on-shore CCS-sites in the Northern German Basin. Additionally fatigue tests were performed via push-pull tests with a series of 30 specimens was tested at stress amplitudes between 150 MPa and 500 MPa (sinusoidal dynamic test loads, R=-1; resonant frequency ~ 30 Hz). Best corrosion resistance in the liquid phase is achieved via normalizing prior to exposure and hardening+tempering at 670 °C leads to lowest corrosion rates in the supercritical phase. With no regard to atmosphere discontinuously ellipsoidal surface corrosion regions appear after exposure of 4000 h and more. The endurance limit of X5CrNiCuNb16-4 measured in air is reduced by more than 50% when exposed to CCS environment (maximum number of cycles (10 x 106) at a stress amplitude of 150 MPa) The scatter range TN = 1:34 is disproportionately large contributing to an overall unusual corrosion behaviour.
Index Terms—Corrosion, CCS, carbon storage, aquifer, heat treatment, fatigue, endurance limit.
Anja Pfennig is with HTW University of Applied Sciences Berlin, Wilhelminenhofstraße 75 A, Gebäude C, 12459, Berlin, Germany (e-mail: firstname.lastname@example.org).
Axel Kranzmann is with BAM Federal Institute of Materials Research and Testing, Unter den Eichen 87, 12205, Berlin, Germany (e-mail: email@example.com).
Cite: Anja Pfennig and Axel Kranzmann, "Potential of Martensitic Stainless Steel X5CrNiCuNb 16-4 as Pipe Steel in Corrosive CCS Environment," International Journal of Environmental Science and Development vol. 8, no. 7, pp. 466-473, 2017.