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 (8–10%) 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.