Electrochemical Corrosion Behavior of 2304 Duplex Stainless Steel in a Simulated Pore Solution in Reinforced Concrete Serving in Marine Environment
The corrosion behavior of rebar steels such as HRB400 plain carbon steel,304 austenitic stainless steel and 2304 austenitic-ferritic duplex stainless steel in an artificial solution,which aims to sim-ulate the fluids in pores of reinforced concrete serving in marine environments,was comparatively investi-gated by means of measurements of open-circuit potential,electrochemical impedance spectrum,dynam-ic potential polarization curve and Mott-Schottky curve etc.The results showed that the corrosion poten-tial of the three rebar steels in the simulated solution increased continuously,the impedance modulus and phase angle peak width increased gradually,and the maximum phase angle shifted to the low frequency direction.Mott-Schottky curve measurement results showed that the point defect density in the passiv-ation film of HRB400 plain steel was high,and that in the passivation film of 2304 duplex stainless steel was minimal.The critical chloride ion concentrations for HRB400 plain steel,304 stainless steel and 2304 duplex stainless steel are in the range of 0.02-0.03,1.5-2.0 and 3.5-4.0 mol/L,respectively.While the ex-cellent resistance to chloride-induced corrosion of 2304 duplex stainless steel was mainly due to the low-er point defect density and compact structure,as well as the enrichment in Cr,Ni,Mo and other corrosion-resistant elements of the passivation film on the steel surface,which enable the passive film stronger re-pulsive effect on the Cl-ions.
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