Modelling the effects of material properties of two low alloyed power plant steels on environmentally assisted cracking in high temperature water

摘要

Based on the recently presented model for the combined anodic path/hydrogen induced stress corrosion cracking of pure iron the effects of hydrogen reduction charges on SSRT fracture strains in high temperature water are established for steels 7CrMoVTiB10 10 and 10CrMo910 in the condition as delivered, 1100°C/water quenched and as welded.The data are implemented into the model for calculation of the effects of hydrogen cracking sensitivity on SCC growth rates at various operational conditions including temperatures, pH and corrosion potentials as well as global stresses. The results confirm that, as a consequence of local acidification at initial anodic path corrosion, hydrogen affected fracture ductility can be a controlling factor for SCC in high temperature water. As a particular effect, intermediate temperatures around 200°C exhibit peak crack growth rates as a consequence of the involved electrochemical reactions.