The Effect Of Molydbate On The Corrosion Resistance And Hydrogen Embrittlement Of 2205 Duplex Stainless Steel

2205 Duplex stainless steels(DSS) with two-phase of austenite-ferrite microstructure have been paid attention because of their outstanding corrosion and mechanical properties in various applications, such as petroleum, chemical and metallurgy.In this paper, microscope, polarization curves, electrochemical impedance, hydrogen permeation curves and slow strain rate stress corrosion testing(SSRT) with scanning electron microscope have been used to investigate the effect of microstructure and Mo O42-on the corrosion resistance and hydrogen embrittlement of 2205 duplex stainless steel. The results revealed that sigma phase dissolved and the volumetric fractions of ferrite and austenite increased by increasing solution treatment temperature from 950℃ to 1150℃. Pitting observation and crack morphology showed that pitting was easier to occur in boundary region between austenite and ferrite, and propagated in ferrite. Moreover, The hydrogen permeation curves with slow strain rate tests show that the diffusion coefficient of H was proportional to the content of ferrite in the matrix; when the content of ferrite and austentite is balanced, the hydrogen embrittlement of materials decreases and the pitting corrosion resisitance improves.By changing concentration of molybdate ion and the temperature of solution, the changes of polarization curves, electrochemical impedance, hydrogen permeation curves and slow strain rate tests of 2205 duplex stainless steel were studied, the changes of corrosion resistance were analysed and the effect of molybdate ion on the corrosion resistance was defined by corrosion morphology and fracture morphology: molybdate ion improved the pitting corrosion resisitance of 2205 duplex stainless steel, decreased hydrogen embrittlement. There is a competitive adsorption between Mo O42- and Cl-, and Mo O42- will form a film by the physical adsorption on the surface, hindering the adsorption of Cl-; molybdate ion or its reaction products could hinder the adsorption of H atom and decrease the hydrogen embrittlement susceptibility, improving the stress corrosion resistance of 2205 duplex stainless steel.The research provides theoretical basis and practice significance for 2205 duplex stainless steel intelligent application in petrochemical, chemical industry and improving performance of 2205 duplex stainless steel.