Hydrogen Entry into a High Strength Steel with Tribocorrosion in Acidic Solution

Abstract

Hydrogen entry into a high strength steel with tribocorrosion in acidic solutions was studied in the present study and it was compared with that in a neutral solution. The samples of SCM 435 high strength steel were subjected to tribocorrosion using a pin-on-disk type wear equipment and to static corrosion in neutral and acidic solutions containing Cl^-. The hydrogen content entered into the steel was measured using hydrogen thermal desorption analysis. In a neutral solution, the hydrogen content in the tribocorroded sample was larger than that in the corroded sample without wear. In the acidic solution of pH 2.7, the hydrogen content in the tribocorroded sample was also larger than that in the corroded sample without wear in the case of 6 and 12 h duration time. On the other hand, the hydrogen content in the corroded sample without wear became larger than that in the tribocorroded sample after 18 h duration time. In the measurement of pH changes of the solution for the duration of 48 h tribocorrosion test and static corrosion test, it is revealed that the pH of acidic solution during tribocorrosion increased from about 2.7 to 6.0, though the pH of the acidic solution during static corrosion test revealed little variation. Because H⁺ consumption by hydrogen generation in cathodic reaction was enhanced with tribocorrosion in acidic solution. The concentration of H⁺ decreased gradually and pH became higher. As a result, corrosion of the steel and hydrogen generation were suppressed and hydrogen entry into the sample was diminished.