Effect of plastic deformation on microstructure and general corrosion behavior of alloy 690 in SG crevice condition of PWR secondary system containing hydrogen

Abstract

The purpose of this study is to elucidate the effect of plastic deformation on the microstructure and general corrosion behavior of Alloy 690 in a simulated steam generator crevice of a pressurized water reactor secondary system containing hydrogen. As the degree of deformation increased, the surface roughness and surface defects such as ripped surface and micro-cracks increased. Compared with the non-deformed specimen, the dislocation density of the deformed specimen greatly increased and the low coincidence site lattice grain boundaries decreased. In all specimens, the plate-like oxide particles were mainly observed with some polyhedral oxide particles. In the case of the corrosion test for 3000 h, the corrosion rates of the 15% and 30% deformed specimens increased by about 1.64 times and 1.76 times, respectively, compared with that of the non-deformed specimen. The effect of the deformed surface of the Alloy 690 is discussed in terms of various surface properties such as surface roughness, surface defects, dislocation density, and grain boundaries.

Keywords

• Alloy 690
• Plastic deformation
• Corrosion
• Microstructure
• Crevice