The period from 1945 to 1974 established diffusion-controlled growth and temperature-dependent kinetics as the central framework for understanding metal oxidation and corrosion. The unification of diffusion processes with protective oxide formation guided research across alloys and coatings, strengthening quantitative approaches to oxide scale behavior and enabling predictive protection strategies. Electrochemical and mechanochemical pathways were integrated to explain dissolution and environmental interactions, while emphasis on composition, microstructure, and diffusion clarified how alloys resist or succumb to oxidation. Historical Significance: This era produced foundational theories and canonical syntheses that shaped subsequent corrosion science, including the parabolic rate-law description of oxide growth and the diffusion-controlled nature of scale formation and spallation. It broadened the corrosion paradigm to infrastructure contexts through diffusion of chlorides in pore solutions and cementitious matrices, and it illuminated pit initiation at inclusions and sulfide phases as critical localized corrosion mechanisms.