Analysis of the various processes downstream cathodic hydrogen charging, II: Charging transients, precharging and natural permeation

Consultant, 36 Chemin Mirassou, 64140 Lons, France
jean-louis.crolet@wanadoo.fr

Received: 2 November 2015
Accepted: 11 March 2016

Abstract

The new views of the subject since 2000 on cathodic hydrogen charging are introduced through the numerical modelling of the downstream hydrogen diffusion, and this Part II deals with other experimental issues not covered in the laboratory permeation described in Part I: these include HIC testing of plane sheet in two-face exposure, SSC testing and cylindrical tensile specimen, necessarily imperfect quenching of precharged specimens, impossible confusion between trapping and poor degassing, and natural permeation in the field. Orders of magnitude are given for the practical application of present calculations, and the role of alloying is also mentioned, as well as that of corrosion layers. An example of what should no longer be done is also discussed, namely the re-use of all the historical calculation tools available in the literature, since they are strictly incompatible with the present views on cathodic charging. Actually, such “approximation” would range from good or fair to awfully poor, but this depends on each calculation type. The method of airstream measurement is also discussed in the light of this new modelling, as well as the basic principles of fitness-for-purpose and application specific testing for full HIC-resistance.