The Corrosion Behavior of X100 Pipeline Steel in a Sodium Chloride Solution Containing Magnesium and Calcium.

ABSTRACT

The influences of Mg2+ and Ca2+ on the short-term (1800 s) corrosion behavior of X100 pipeline steel were investigated in a sodium chloride (NaCl) solution saturated with CO2. Either Ca2+ or Mg2+ in the solution inhibited the short-term corrosion of X100 pipeline steel, with the corrosion current density decreasing from 262.4 µA cm-2 to 163.5 µA cm-2 or 80.8 µA cm-2. During longer-term (8-48 h) immersion, the Mg2+ inhibited the formation of the protective scale, whereas the Ca2+ accelerated the formation of the scale. Further, an experimental equation establishing the relationship between the precipitation rate of the corrosion scale and the exposure time was proposed to quantitatively study the effects of Mg2+ and Ca2+ on the precipitation rate of the corrosion scale.