HOLISTIC-PROBABILISTIC STUDIES ON LOCALIZED AND GENERAL CORROSION

摘要

Corrosion phenomena are deeply characterized by an intrinsic probabilistic nature. Starting from a statistical approach to localized corrosion, the concept of holism and holistic study is introduced in facing up to localized corrosion. From comparison of the probabilistic fluctuations of threshold potentials and corrosion potentials, statistical parameters are deduced to rank different materials, environments and designs in relation to specific material/environment/design combinations. Cumulate frequency F is considered for breakdown (b) and for corrosion (c) potential (E) and both F_b and F_c are represented on a logarithm-arithmetical plot as E=E(log F). Cumulate frequency H, corresponding to E_b=E_c, can be related to the in service behavior of the material in a specific environment and with a specific design. Through this representation in localized corrosion, H can be formally related to the corrosion current (ⅰ) of general corrosion approach. Analogy between localized and uniform corrosion is related to corrosion simulation by statistical method and to in time evolution of surface roughness during general corrosion of stainless steels.