Corrosion is a major source of degradation of capability and availability of military assets in the U.S. Department of Defense (DoD). According to the latest study on the impact of corrosion within the DoD,1 the cost of corrosion is $20 B per year, and accounts for 10% of the total non-available days (NAD) for DoD assets—whereas in the case of Naval Aviation corrosion accounts for 31% of NAD. The complexity of weapons systems requires a multi-pronged approach to address corrosion issues including short- and long-term investments—from basic and applied research to demonstration and implementation efforts. Specifically, basic and applied research play a crucial role in the advancement of solutions to materials and corrosion issues that impact current and future readiness. Collaboration between academia, industry, and DoD laboratories has advanced our knowledge about corrosion mechanisms and promoted the development of new technologies.
In this Special Issue of CORROSION, this long-standing collaboration is once again highlighted, focusing on some of the best basic and applied research addressing current DoD needs. The 11 manuscripts selected for this issue touch on topics including coatings and primers, galvanic interactions, monitoring and simulation of atmospheric corrosion, hydrogen assisted fatigue, and accelerated corrosion testing. For example, metal-rich primers continue to be an area of intense research due to their ability to sacrificially protect a variety of substrates, including aluminum. The paper by Santucci, et al., describes the use of magnesium and magnesium oxide-rich primers for the sacrificial protection of aluminum substrates as tested in outdoor exposures. The non-destructive evaluation of coating systems is explored by Borth, et al., using the scanning Kelvin probe technique, specifically to assess the degradation of the coatings and the onset of corrosion.
In the area of galvanic interactions, modeling of galvanic corrosion for damage prediction is explored by Liu, et al., under thin film conditions using the Laplace equation. In addition, Williams and Thompson use mixed potential theory to model galvanic corrosion and generate risk maps of aircraft components. Moran, et al., studied the effect of galvanic acceleration on crevice corrosion between aluminum substrates and cadmium-plated steel fasteners. The role of relative humidity on atmospheric corrosion is described by Boswell-Koller and Rodriguez-Santiago, who developed a statistical methodology to correlate time of wetness and corrosion severity. Similarly, Niebuhr, et al., studied the effect of drying and wetting on the fatigue crack growth rate of AA7075. A relevant topic is the performance of high-strength steel for landing gear applications. Boellinghaus, et al., studied hydrogen assisted stress corrosion cracking of high-strength steels and their material properties in the as-received and in-service conditions.
Finally, accelerated testing is explored. Rausch, et al., developed a test methodology to investigate the effects of environmental parameters on fatigue crack growth rates of cracks nucleating from corrosion pits. Parker and Kelly explored exfoliation susceptibility as revealed by comparing and contrasting two standardized tests and identifying the relevant parameters that contribute to exfoliation damage. Lastly, Bland, et al., compared the corrosion performance of AA7075 and AA2070, and some of their tempers, in various accelerated test environments.
We are grateful and honored to be able to work with the editors and staff of CORROSION in our role as guest editors, and greatly appreciate their support, which was critical in assembling this special issue. We also want to thank the associate editors and reviewers who contributed with their time and expertise. We hope you enjoy the great work of the authors highlighted in this issue. Thank you!
