Hydrogen Assisted Cracking and Corrosion of Some Highly Corrosion Resistant Alloys

Project goals in this study focused on localized corrosion and hydrogen embrittlement. The former emphasized grain boundary and crevice corrosion. Research on the latter has improved understanding of the intrusion of hydrogen into metals and an improved capability of preventing hydrogen assisted cracking of structural members. Results have been obtained on hydrogen absorption from the gas phase using the scanning tunneling microscope STM. These results, which characterize the absorption process at an atomic scale, provide the capability of STM for studying the H-material interaction. Another important advance is the development of a theoretical basis for hydrogen entry into a metal during cathodic charging from aqueous solution. Models enable previously unavailable parameters to be determined from steady state hydrogen permeation. As a result, application of the model can provide new diagnostic criteria for determining the role of various system parameters in modifying the rate of hydrogen entry.