INFLUENCE OF SOLUTION ENVIRONMENT AND HYDROGENON ELECTROCHEMICAL BEHAVIOUR AND NEAR-NEUTRALSCC OF PIPELINE STEELS

摘要

The electrochemical behaviours of two common pipe steels X70 and 16Mn were investigatedrnpotentiodynamically in a range of near-neutral bicarbonate solutions. The influences of bicarbonate,rnchloride ions and precharged hydrogen on polarization characteristics were investigated as well asrnpassivation behaviour of pipeline steels. The hydrogen electrochemical oxidation method was used torndetermine the total amount of hydrogen absorbed by pipeline steels under cathodic charging at variousrnconstant potential. It has been shown that the shapes of the polarization curves of pipeline steel variedrnwith bicarbonate concentration. Bicarbonate ions, chloride ions and absorbed hydrogen all can promoternthe anodic dissolution. The hydrogen concentration in specimen increase as the cathodic prechargedrnpotential increased but a distinct peak at about -850mV (SCE).