Effect of deformation twinning on dissolution corrosion of 316L stainless steels in contact with static liquid lead-bismuth eutectic (LBE) at 500 C

This work addresses the effect of deformation twinning on the dissolution corrosion behaviour of 316 L austenitic stainless steels in contact with static liquid lead-bismuth eutectic (LBE). For this purpose, plastically deformed 316 L steel specimens with distinctly different deformation twin densities were simultaneously exposed to oxygen-poor (<10-13 mass%) static liquid LBE for 1000 h at 500 C. The variation in deformation twin density was achieved by loading in uniaxial tension to similar degrees of plastic deformation (8e10%) specimens made of the same 316 L steel heat. Tensile loading was carried out at - 150, 25 and 150 C so as to affect the twin density, which increased as the temperature of plastic deformation decreased. Dissolution corrosion was the only liquid metal corrosion mechanism observed in the LBE-exposed steel specimens. The thickness of the dissolution-affected zone increased with the deformation twin density, which was highest in the 316 L steel specimen deformed at - 150 C and lowest in the one deformed at 150 C. As deformation twin boundaries accelerated the LBE ingress into the steel bulk, their local orientation with respect to the steel specimen surface affected the thickness of the dissolution-affected zone.