Materials and Environmental Circumstance: And All is Always Now

摘要

This paper offers a summary of the author's contributions in the field of fracture, damage tolerance and microstructural integrity of materials in a hydrogen environment. Paraphrasing the famous sentence by Ortega y Gasset "yo soy yo y mi circunstancia", one could say that the material is itself and its circumstance, the latter being the physico-chemical and mechanical environment. The paper analyzes situations in which the circumstance enhances hydrogen embrittlement, and it is divided into three main sections. Firstly, the effect of hydrogen on structural steels (pearlitic and austenitic) is revised, covering experimental, numerical and analytical aspects. Later, the study is extended to pearlitic steels with different degrees of cold drawing, on the basis of a materials science approach (relationship between microstructure and properties). Finally, a theoretical study is provided of the validity of the fracture mechanics approach to the phenomenon of hydrogen assisted cracking, analyzing the K-dominance condition to elucidate the role of the far field and the effect of history, the latter recalling the words of the Spanish poet Antonio Machado: "hoy es siempre todavia", and perhaps T. S. Eliot's "and all is always now".