Hydrogen Embrittlement of X70 Steel under Cathodic Protection

The hydrogen evolution potential and hydrogen embrittlement region of X70 steel in 3% (mass fraction) NaCl solution were determined by polarization curve test and slow strain rate test. The relationship between cathodic polarization degree and hydrogen embrittlement was illustrated by electrochemical impedance spectroscopy. The results show that the potential of hydrogen evolution reaction for X70 steel in 3%NaCl solution was -1.0 V. With the increase of cathodic polarization degree, the hydrogen embrittlement sensitivity increased, because the charge transfer resistance decreased, which promoted the formation of adsorbed hydrogen.