Doel 3 & Tihange 2 - Some Peer-reviewed Scientific Papers & Reports

Int. J. Pres. Ves. & Piping 24 (1986)13-26

Hydrogen and Radiation Embrittlement of CrMoV and CrNiMoV Ferritic RPV Steels

J. Kou t s k~ and K. ~pl ichal

NuclearResearchInstitute, i~e~,Czechoslovakia

(Received:20 November, 1985)

ABSTRACT

Hydrogen embrittlement of low-alloy steels has been investigated in relation to its dependence on hydrogen trapping and release, on the electrolytic hydrogen charging parameters, and on irradiation. The interaction of hydrogen with the structure of irradiated and unirradiated steels at higher charging current densities causes structural defects which can lead to a loss of ductility of the steel even after hydrogen release. The presence and the character of grain boundaries, secondary phases and other defects in the steel structure are of great importance from the viewpoint of the hydrogen embrittlement effect.

INTRODUCTION

In recent years, increasing attention has concentrated on the problem of the through-wall direction failure possibility in corrosion-resistant welded cladding and the development of underclad cracks and other types of cracks in the base material of PWR pressure vessels. Crack growth in the presence or absence of a corroding environment can be affected by hydrogen and radiation embrittlement. In the present paper the conditions of hydrogen trapping and release have been studied in relation to their dependence on the presence of structural defects in both irradiated and unirradiated steel. The influence of these parameters has been determined from the decrease in ductile and strength properties of the steel. 13 Int. J. Pres. Ves. &Piping 0308-0161/86/$03.50 © ElsevierAppliedSciencePublishers Ltd, England, 1986.Printedin Great Britain