Proceedings of the Third International Conference on Metals & Hydrogen I03

Mitigation of Hydrogen-Induced Intergranular Cracking in Al-Mg Alloys Using Various Methods of Electrochemical Potential Control

M. E. McMahon (1)1 , J. R. Scully (1)1 , J. T. Burns (1)1

  • (1) 1

    Center for Electrochemical Science and Engineering, Department of Materials Science and Engineering, University of Virginia, Charlottesville, VA 22904


Hydrogen-induced intergranular stress corrosion cracking (IG-SCC) of a single edge notch sample is rapidly mitigated in the Al-Mg alloy AA5456-H116 at post-threshold, constant stress intensity of 10 MPa√m through cathodic polarization. Actively growing cracks (at -0.8 VSCE) would exhibit a reduction in growth rate of up to three orders of magnitude within an average of 20 seconds following cathodic polarization. Similar levels of mitigation in 0.6 M NaCl were achieved for polarization via a potentiostat, coupling with a pure zinc anode (with an exposed area as low as 0.03 cm2 (1 Zn : 110 AA5456 area ratio)), and an inorganic zinc-rich primer (with an exposed area as low as 0.67 cm2 (67 primer : 350 AA5456 area ratio)). Reapplication of -0.8 VSCE following 5 hours of cathodic protection caused crack growth rate increase of two to three orders of magnitude within an average of 20 seconds. Anodic current response tests on inorganic Zn-rich primer demonstrated that the primer galvanic protection is less effective in more aggressive salinity and during rapid crack growth due to a depressed anodic current response that worsens with time.


  • aluminum alloy
  • sacrificial protection
  • cathodic protection
  • zinc primer
  • chloride
  • galvanic protection
  • hydrogen embrittlement
  • intergranular fracture