Study On Corrosion Behavior Of High Nitrogen Austenitic Stainless Steel In Liquid Lead-bismuth Eutectic Alloy At 400?

Liquid lead-bismuth eutectic alloy(LBE)has become the material of choice for the fourth-generation reactor coolant and accelerator-driven sub-critical system coolant and hash target.However,long-term exposure of structural materials to liquid leadbismuth eutectic alloy can cause severe corrosion.The erosion of structural steel by liquid LBE with high flow rate will further complicate the corrosion process.Austenitic stainless steel is a candidate structural material for the cladding and loop piping of the fourth-generation reactor,but during the corrosion process,the preferential dissolution of Ni will aggravate the corrosion.The characteristics of high nitrogen austenitic stainless steel with low Ni and high Cr meet the requirements of nuclear structural steel materials.Therefore,studying the corrosion behavior of high nitrogen austenitic stainless steel in static and dynamic LBE has important theoretical significance and practical application value.In this paper,high-nitrogen austenitic stainless steels H1,H2,and H3 with different N content are selected as the research objects.The static corrosion test device made by the research group is used to test the liquid Corrosion tests of 500,1000,1500,2000,3000 h were carried out in lead-bismuth eutectic alloy;the dynamic corrosion test device was used to test the high nitrogen austenitic stainless steel H1,H2,H3 at 400?with different relative flow rates(0,0.92,1.27,1.69,2.01 m/s)Corrosion in liquid leadbismuth eutectic alloy for 1000 h.Scanning electron microscope(SEM),energy spectrometer(EDS),X-ray diffraction(XRD)scanning,and laser confocal microscope(LSCM)were used to analyze the surface and cross-section of the corroded sample.The dynamic test results show that the initial oxidation layer prevents the further oxidation of the high nitrogen austenitic stainless steel H1 under the static corrosion condition(0m/s).Under the dynamic corrosion condition,the initial oxide layer on the surface is destroyed,and the oxide content on the surface increases first and then decreases with the increase of the relative flow rate.The relative flow rate increases from 0 to 0.92m/s,and the destruction of the initial oxide layer leads to diffusion oxidation of the alloy below the surface layer,mainly oxidation corrosion.The relative flow rate increases from 0.92 m/s to 2.01m/s,and the larger relative flow rate takes away the alloying elements diffused to the surface in time,and the oxidation corrosion gradually changes to the dissolution corrosion.The high N content in H2 and H3 austenitic stainless steels weakens the oxidation of metal by oxygen.At different relative flow rates,the corrosion is mainly dissolved,and the oxidation corrosion is relatively small.Comprehensive comparison of corrosion resistance of high nitrogen austenitic stainless steels H3>H2>H1.