Effect of temperature on pitting corrosion behavior of 2507 steel in simulated flue gas desulfurization solution
Super duplex stainless steel(SDSS)has promising applications in flue gas desulfurization(FGD)due to its excellent corrosion resistance and superior mechanical properties as well as its cost-effectiveness.The pitting behav-ior of 2507 SDSS in flue gas desulphurization condensate at different temperatures(20,40,60,80 ℃)was studied in depth using metallographic microscope,scanning electron microscope and electrochemical workstation.The findings demonstrate that at a solution temperature of 40 ℃,the test steel has the best corrosion resistance with corrosion po-tential(Ecorr)of-0.078 V,corrosion current density(icorr)of 5.09 mA/cm2,pitting potential(Epit)of 0.956 V,the largest impedance spectrum radius and a charge transfer resistance(Rct)of 54 200 Ω/cm2.The impedance modulus at a frequency of 0.01 Hz | Z| f=0.01 Hz is 52 036 Ω.When the solution temperature was increased from 20 ℃ to 80 ℃,the Ecorr and Epit of the specimen increased first and decreased,the icorr decreased first and increased,the electrochemical impedance spectrum radius increased first and decreased,the Rct increased first and decreased,the number of pitting pits after corrosion decreased first and increased,the pitting corrosion resistance of the sample increased with an in-crease in temperature followed by a decrease.The analysis suggests that this is the result of the combined effect of the two opposite effects of temperature on the electrochemical process(blocking effect of reduced oxygen content and the promoting effect of increased ionic activity).When the temperature is below or at 40 ℃,the mass concentration of dissolved oxygen decreases,the activity and reaction ability of Cl- are weak,and the blocking effect of reduced ox-ygen content dominates.With the increase of temperature,the pitting corrosion resistance of 2507 SDSS is im-proved.when the temperature is above 40 ℃,high temperature will enhance the activity of corrosive halogen ions and their reactivity,Cl- activity to enhance the promotion of the effect of the dominant role.With the increase of temper-ature,the pitting corrosion resistance of 2507 SDSS decreases.
super duplex stainless steelflue gas desulfurizationtemperatureelectrochemistrypitting potential
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