| Lead bismuth eutectic alloy（LBE）has been considered as a primary candidate coolant for lead-cooled fast reactor（LFR）of the fourth generation nuclear energy system as well as a coolant and a spallation target for accelerator driven sub-critical system（ADS）,due to its exceptional thermal physical and chemical properties.321,410 and 430 stainless steels have excellent corrosion resistance,high temperature performance and thermal conductivity.321,410and 430 stainless steels are candidate materials for the structural materials of the nuclear reactor coolant main pipelines.However,LBE has a strong corrosion effect on structural steel materials at high temperature.Therefore,it has great practical significance and application value to study the corrosion behavior of 321,410 and 430 stainless steels in LBE to provide reliable data support for the practical application of 321,410 and 430 stainless steels in nuclear reactor in the future.The effect of corrosion time on corrosion behavior of stainless steel in static LBE was studied.321,410 and 430 stainless steels were immersed in static LBE at 550°C for 200 h,400h and 600 h.The results showed that 321 stainless steel exhibited dissolution-corrosion,and the diffusion layer formed at the interface between 321 stainless steel and LBE.With the corrosion time prolonging,the diffusion layer gradually thickened.Oxidation-corrosion and dissolution-corrosion mainly occurred on the surface of 410 and 430 stainless steels,and oxide generated at the interface between steel materials and LBE.With the corrosion time prolonging,the oxide gradually grew,that is,the corrosion degree gradually intensified.The oxidation-corrosion degree of 410 stainless steel was stronger than 430 stainless steel,and the dissolution-corrosion degree of 430 stainless steel was stronger than 410 stainless steel.The effect of corrosion time on corrosion behavior of stainless steel in dynamic LBE was studied.321,410 and 430 stainless steels were immersed in dynamic（2.98 m/s）LBE at 550°C for 200 h,400 h and 600 h.The results showed that oxidation-corrosion and dissolution-corrosion occurred on the surface of 321,410 and 430 stainless steels.The surface of the corrosion samples produced oxide,which gradually formed an oxide layer with a two-layer structure,including an outer oxide layer and an inner oxide layer.The outer oxide layer was composed of loose Fe3O4 and permeable Pb-Bi,and the inner oxide layer was composed of dense（Fe,Cr）3O4.The dense inner oxide layer could hinder the direct contact between the steel materials and LBE to slow down the corrosion rate.The effect of flow velocity of LBE on corrosion behavior of stainless steel in LBE was studied.321,410 and 430 stainless steels were immersed in LBE with different relative velocities at 550°C for 600 h.The relative velocities were 0 m/s,1.70 m/s,2.31 m/s and 2.98m/s.The results showed that the oxide film with double-layer structure was detected on the corrosion sample surface.With the increase of relative velocity,the oxide layer thickness on the corrosion sample surface gradually increased,that is,the increase of velocity promoted corrosion.With the same relative velocity,321 stainless steel surface produced the thinnest oxide layer,and410 stainless steel surface produced the thickest oxide layer.The contents of Fe,Cr and Ni in 321,410 and 430 stainless steels were different,leading to different degrees of corrosion in LBE.The Ni content in 321 stainless steel was the highest,and the degree of dissolution-corrosion was the most serious.The Cr content of 410 stainless steel was lower than 430 stainless steel,so the dissolution-corrosion degree of 410 stainless steel was weaker than 430 stainless steel,and the oxidation-corrosion degree was stronger than 430stainless steel.Under the same corrosion conditions,the oxidation-corrosion rate of the three kinds of stainless steel was 410>430>321,and the dissolution-corrosion rate was 321>430>410. |
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