Hydrogen is often produced, absorbed, and potentially exerts various deleterious effects on the mechanical properties of many engineered materials. This in turn affects the service life of many metallic components. It is therefore essential for industry to understand, anticipate, and manage the hydrogen embrittlement threat and to be fully prepared for future challenges in the form of both emerging high performance material, harsh environments, and high mechanical driving forces.

In May 2018, OCAS—the Flemish research center for the application of steel—organized its 3rd international SteelyHydrogen conference, fully focused on the interactions between metals and hydrogen. The organizers of SteelyHydrogen aimed for symposium content ranging from highly technological to purely scientific, offering a well-balanced forum for discussion of both final applications and academic research. As a result, the program blended industrial hydrogen embrittlement issues and solutions with scientific research on theoretical aspects sometimes using model materials as well as the state-of-the-art presentation and review of on methodology developments.

For its 3rd edition, it is evident that hydrogen embrittlement is not only a challenge for steels but also for many other metals. In this edition, the scope of materials was expanded from mainly steels (low carbon and stainless steels) to include other metals such as titanium, aluminum, and nickel-based alloys. This resulted in a conference attendance of 175 researchers. The expanded scope enriched the scientific discussions and brought new perspectives to the forefront on the most recent research concerning hydrogen-metal interactions and hydrogen embrittlement. Bridges were made during the conference to connect and exchange information on numerous technical issues related to hydrogen in final applications, the research methodologies, as well as the scientific findings for the different metals and alloys.

The SteelyHydrogen2018 scientific jury consisted of 10 renowned experts in the area of hydrogen effects that chaired the sessions and judged the award competition for the “Best SteelyHydrogen2018 paper” and “Best SteelyHydrogen2018 Poster.” The outcome is this special section of CORROSION which reflects well the multidisciplinary spirit of the conference. The six selected manuscripts published herein include the state-of-the-art research on hydrogen embrittlement and hydrogen-microstructure interactions for steels and other metals such as Ni and Al-Mg alloys from different points of view: a fracture mechanics study on pressure vessel steels (Somerday and Nibur), microstructural influences in TRIP-aided bainitic ferrite steels (Bollinger, et al.), hydrogen visualization by neutron imaging (Pfretzschner, et al.), H-charging of duplex stainless steels (Claeys, et al.), superabundant vacancy formation in Ni single crystals (Metsue, et al.), and mitigation of intergranular cracking in Al-Mg alloys (McMahon, et al.).

We are grateful and honored to have been be able to work with Prof. Scully, the editors, as well as staff of CORROSION in our role as guest editors and greatly appreciate their efforts. The reviewers of the manuscript published are commended for their insightful comments and timely delivery of their assessments. We also want to thank the participants of SteelyHydrogen2018 for their top-quality contributions helping this conference to grow and achieve international recognition. We hope you enjoy the selection of contributions highlighted in this special issue and hope to welcome you at the next edition of the SteelyHydrogen conference in 2021 (details available at www.steelyhydrogen2021.be).