Electrochemical hydrogen discharge of high-strength low alloy steel for high-pressure gaseous hydrogen storage tank: Effect of discharging temperature

Hydrogen discharge technique of high-strength low alloy steel for high-pressure gaseous hydrogen storage tank was developed by using an electrochemical technique. The electrochemical hydrogen discharge of high-strength low alloy steel were investigated in a deaerated borate buffer solution (0.3 M H₃BO₃ + 0.074 M N₂B ₄O₇, pH = 8.4). By applying a potential of +630 mV _SCE which is higher than the hydrogen equilibrium potentials and lower than the pitting potential, the oxidation reaction of metal (Fe → Fe²⁺ + 2e^-) is limited and oxidation reaction of the hydrogen (H₂ + 2OH^- → 2H₂O + 2e ^-) was induced simultaneously. Thus, the pre-charged hydrogen inside the specimen was eliminated effectively without any damage to the specimen. The electrochemical hydrogen discharge method was performed at 25 °C, 50 °C and 75 °C. The efficiency of hydrogen discharge was accelerated with increasing temperature because the exchange current density of hydrogen is increased with temperature.