Effect of electrolyte composition on crack growth rate in pipeline steel

• Electrolyte composition can strongly affect the rate of crack growth in pipe steel.
• The crack growth is accelerated in the presence of metal dissolution activators.
• Corrosion inhibitors enhance the resistance of steel against SCC.
• The cathodic polarization of steel can inhibit crack growth.

Electrolyte composition can strongly affect the rate of crack growth in pipe steel X70. A weakly acidic citrate buffer (pH 5.5) and a mixture of NS4 solution with a borate buffer (pH 7) were used as background solutions under static and cyclic strain, respectively. Various compounds that affect steel dissolution and hydrogen absorption rates were added to the solutions. Crack growth is accelerated in the presence of metal dissolution activators but hindered upon addition of a corrosion inhibitor. Hydrogen absorption promoters do not accelerate the crack growth at the corrosion potential.