Effect of Temperature on Corrosion Resistance of UNS N08825 Alloy under Environment with High Content of H2S
The 72 h immersional and electrochemical corrosion tests of UNS N08825 alloy were carried out under environment with different temperature(80,90,110,132 ℃),high pressure,high content of H2S/CO2 and high chloride ion content.The effect of the temperature on the corrosion resistance of the alloy were studied,and the effect mechanism was analyzed.The results show that no corrosion occured in the alloy at 80 ℃.Black corrosion product appeared on the surface of the alloy at 90,110,132 ℃.After corrosion at 110,132 ℃,the corrosion products increased in amount and showed loose porous characteristics.With the increase of temperature,the number and depth of pitting on the surface of the alloy increased,and the maximum pitting rate and uniform corrosion rate increased.With the increase of temperature,the self-corrosion potential,charge-transfer resistance and passivation film resistance of the test alloy decreased,and the self-corrosion current density increased.When the temperature was lower than 90 ℃,the passivation film on the alloy surface was uniform and dense,the pitting sensitivity was low,and the corrosion resistance was relatively good.When the temperature was not lower than 90 ℃,the hydrolysis of elemental sulfur was intensified,the passivation film on the alloy surface was destroyed,the pitting corrosion was more likely to occur,and the corrosion resistance became worse.
high temperature and high pressureUNS N08825 alloyH2Schloridionelectrochemistrypitting
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