COMPATIBILITY OF FERRITIC/MARTENSITIC STEEL T91 WITH FLOWING LBE CONTAINING 10~(-7) MASS DISSOLVED OXYGEN AT 450 AND 550°C

摘要

Corrosion behavior of ferritic/martensitic (F/M) steel T91 with 9 % nominal chromium content was investigated in flowing (2m/s) Pb-Bi eutectic (LBE) with 10~(-7) mass% dissolved oxygen at 450 and 550°C for up to 8766 and 2011 h, respectively. The corrosion process and material loss were analyzed. The steel generally shows oxidation consisting of the formation of an Fe-Cr spinel layer. Oxidation resulted in metal recession which does not exceed ～ 10 μm after 8766 h at 450°C and ～15 μm after 2011 h at 550°C. Local liquid-metal attack in the form of pits occurs at both temperatures. At 450°C, remarkable liquid-metal attack is observed after 5015 h, while, at 550°C, it is found already after 1007 h. The maximum depth of local attack reaches 960 μm after 8766 h at 450°C, and 190 μm after 1007 h at 550°C. The obtained results are compared with previous experiments at similar testing conditions, except for a higher oxygen concentration of 10~(-6) mass%.