Corrosion mechanism for API P105 steel in the CO, saturated solution with C
l- was studied by using electrochemical impedance spectroscopy(EIS) and pol
arization measurements. The results showed that Cl- promoted the dissolutio
n of iron, and the order of the electrochemical reaction was 0.7, Cl- did n
ot take part in. the cathodic reaction, the main cathodic reaction was cont
rolled by the depolarization reaction of H2CO3.