###### Abstract  
The corrosion rate of carbon steel under the attack of electrolytic mediums saturated by CO\({}_{2}\) at a working temperature of 65 \({}^{\circ}\)C under dynamic conditions is studied in this paper. The effect of Ca\({}^{2+}\) ions on corrosion rates and their dependency on the associated anion (Cl\({}^{-}\) or CO\({}_{3}\)\({}^{2-}\)) with respect to the Ca\({}^{2+}\) cation and Na\({}^{+}\) are also assessed. A potentiostat/galvanostat associated with a rotor stator in an AISI 1040 steel-ring configuration, rotating at 600 rpm, was used. A linear polarization-resistance technique was applied to calculate the corrosion rate. It is found that the corrosion rate depends not only on the presence of Ca\({}^{2+}\), but also on the salt anion added to the electrolytic medium. There was a strong inhibitory effect of the corrosion in the presence of Ca\({}^{2+}\) in chloride-free mediums because of an ankerite deposition with a lower solubility compared to siderite. Moreover, it was observed that, even if the corrosion rate increased together with the Cl\({}^{-}\) concentration, its value depended on the cation introducing the anion. It was higher when Cl\({}^{-}\) was associated with Na\({}^{+}\) compared to when it was associated with Ca\({}^{2+}\). We found the following decreasing order in the carbon steel corrosion rate: 2% NaCl + 1380 ppm CaCl\({}_{2}\) > 2% NaCl >  
Numerous studies have alluded to the effects of FeCO\({}_{3}\) in relation to the corrosion rate suppression of carbon steel in CO\({}_{2}\)-containing environments [5]. Although few studies assess the effect of Ca\({}^{2+}\) anions on sweet corrosion [6], many works on Ca\({}^{2+}\)-rich solutions do not explicitly state the salt added to the simulated medium. [PERSON] et al. [6] reviewed the works related to this topic, referring to Ca\({}^{2+}\) or Mg\({}^{2+}\) concentrations but with no record of the anion used by the researchers. [PERSON] et al. [7] assessed the effect of calcium ions on the pitting corrosion of N80 steel. They worked with 3% NaCl, 4.5% NaCl, and 3.5% NaCl + 1.5% CaCl\({}_{2}\) solutions saturated by CO\({}_{2}\) at 57 \({}^{\circ}\)C in stagnant and dynamic conditions. They pointed out that the initiation period of pitting corrosion was indicated by an abrupt decrease in the magnitude of the impedance, which was observed at 70 h of immersion in 3% NaCl, at 49 h in 3.5% NaCl + 1.5% CaCl\({}_{2}\), and at 23 h in 4.5% NaCl. They concluded that in stagnant conditions without Ca\({}^{2+}\), the corrosion rate increased together with the increase in chlorides. However, for solutions with the same Cl\({}^{-}\) concentration, the corrosion rate decreased due to the addition of Ca\({}^{2+}\). They pointed out that the initiation period of pitting corrosion decreased as the Cl\({}^{-}\) concentration increased; however, at the same concentration of this ion, Ca\({}^{2+}\) prolonged the initiation period [7]. [PERSON] et al. [8] studied the effect of Ca\({}^{2+}\), by adding it to the solution as CaCl\({}_{2}\), on the CO\({}_{2}\) corrosion of API 5L-X65 steel. They simulated a formation water to which they added 64, 128, 256, and 512 mg/L of Ca\({}^{2+}\) under stagnant conditions at a 1 MPa partial pressure of CO\({}_{2}\) at 75 \({}^{\circ}\)C. They concluded that the corrosion rate increased as the Ca\({}^{2+}\) ions' concentration increased. [PERSON] et al. [9] studied the effects of Ca\({}^{2+}\) ions on the CO\({}_{2}\) corrosion of API 5L-Gr B steel under stagnant conditions at 80 \({}^{\circ}\)C. They obtained measurements using two mediums saturated by NaCl and CO\({}_{2}\) (15 MPa), differentiated by the presence or absence of CaCO\({}_{3}\) (0.5 mol/kg), attacking the graduated cylinders for 72, 336, and 672 h. They concluded that the uniform attack was predominant for both solutions, with a preferential dissolution of ferrite. They also reported that the corrosion rate by weight loss decreased over time and it was always lower for the CaCO\({}_{3}\) solution.