Influence of Surface Quality on the Corrosion and Corrosion Fatigue Behavior of High Alloyed Steels Exposed to Different Saline Aquifer Water Environments

Abstract

Coupons of X5CrNiCuNb16-4 with different surface roughness that may be utilized as injection pipe with 16% Chromium and 0.05% Carbon (1.4542, AISI 630) were exposed for 3000 h to CO 2 -saturated saline aquifer water simulating the conditions in the Northern German Basin at ambient pressure and 60 °C. Additionally, corrosion fatigue experiments (ambient pressure, technically clean CO2, saline aquifer water of Stuttgart Aquifer) were performed using specimen of X46Cr13 (1.4043, AISI 420C) with regard to the influence of the roughness of technical

Corrosion and Corrosion Fatigue of Steels in Downhole CCS Environment—A Summary

“…The specially designed electromagnetically powered gear type pumps the corrosion medium from the reservoir to the pump, into the corrosion chamber, and back into the reservoir (Figures 1 and 2) at a real flow rate of V* = 2.5× 10 −6 m 3 /s and the theoretical flow rate of ω0 = 1.7 × 10 −3 m/s at the critical specimen section. For CCS simulation, the technical CO2 flows into the closed system at approximately 9 L/h [35,36,38,52,79,89,91,93,100,106]. A titanium/titanium-mixed oxide electrode with no electrical contact with the specimen or chamber provides a constant potential [100,106].…”

“…The surface quality of steels directly influences the corrosion fatigue behavior [72][73][74][75][76][77][78][79][80], which is improved by smooth surfaces [81], deeper plastic deformations and compressive surface stress [82][83][84], shot peeing [85], and in ferritic stainless steel when R a exceeded 0.5 µm [86]. The corrosion fatigue resistance of X2CrNiMoN22-5-3 under different environments [87][88][89][90] has first been tested under in situ geothermal conditions [91][92][93] and the results are now combined.…”

Degradation of AISI 630 exposed to CO2-saturated saline aquifer at ambient pressure and 100 bar

“…2. Schematic set-up of operating corrosion chamber for in-situ corrosion fatigue testing [15], [40].…”

“…The corrosion fatigue strength of stainless steel with16% chromium AISI 630, hardened and tempered with martensitic microstructure) is examined in dynamic stress-strain tests in CO2-saturated aquifer (Stuttgart Aquifer [40]) at 60 °C. Therefore a resonant testing machine (sinusoidal dynamic test loads, R=-1; resonant frequency ~ 30 Hz) has been used.…”

“…Surface corrosion layers grow slowly and locally corroded samples usually show the same corrosion products as surface layers [15], [17], acting as corrosion catalyser. Generally siderite FeCO3 [3], [38], [39], [40] is formed on steels exposed to CO2-environment (a) due to the low solubility of FeCO3 in water (pKsp = 10.54 at 25 °C [29], [37]) leading to anodic iron dissolution. The initial formation of transient Fe(OH)2 [6], [30] (grey area in: a) possibly leads to an increase of the local pH near the hydroxide film.…”