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本文通过电化学动电位再活化法(EPR)并结合扫描电镜(SEM)和金相显微镜评价了热处理温度对304不锈钢晶间腐蚀的影响。同时研究了不同敏化程度的304不锈钢铬离子析出量情况,以及浸泡时间和浸泡温度对同一敏化程度的不锈钢铬离子析出量的影响。实验结果表明,304不锈钢在低温下进行热处理,可以避免晶间腐蚀的发生。在500℃~650℃下热处理,随着温度的上升样品的敏化度增加,并在650℃左右尤为严重。随着温度的继续上升,样品的贫铬现象弱化,敏化度下降。在酸性溶液中随着敏化度的升高,晶间腐蚀所导致的铬析出量也随着增加。但在中性溶液中,敏化度高低对铬析出量影响甚小。在不同浸泡液中,浸泡时间的延长对试样的自腐蚀电位有着不同程度的影响,从而改变试样的耐腐蚀性能。浸泡液温度的上升,均会加速已发生敏化的试样腐蚀,使得铬离子析出量增大且在含氯酸性溶液中铬离子析出量最为严重。
In this paper, the influence of heat treatment temperature on the intergranular corrosion of 304 stainless steel was evaluated by electrochemical potentiodynamic reactivation (EPR) combined with scanning electron microscopy (SEM) and metallographic microscope. At the same time, the amount of chromium ion precipitation of 304 stainless steel with different sensitization degree and the effect of immersion time and immersion temperature on the amount of chromium ion precipitation of stainless steel with the same sensitization degree were studied. The experimental results show that 304 stainless steel is heat treated at low temperature to avoid intergranular corrosion. Heat treatment at 500 ℃ ~ 650 ℃, with the increase of temperature increased the sensitivity of the sample, and particularly severe at about 650 ℃. As the temperature continues to rise, the sample of chromium depletion weakening, sensitization decreased. With the increase of sensitization degree in acid solution, the amount of chromium precipitation caused by intergranular corrosion also increases. However, in neutral solution, the level of sensitization has little effect on the amount of chromium precipitation. In different soaking solutions, the lengthening of immersion time affected the self-corrosion potential of the samples to varying degrees, which changed the corrosion resistance of the samples. Soaking liquid temperature rise, will accelerate the sensitization of the sample has been accelerated corrosion, making the precipitation of chromium ions increased and in the chlorinated acidic solution of chromium ion precipitation is the most serious.