恒电位脉冲法检测奥氏体不锈钢敏化

DETECTION OF SENSITIZATION OF AUSTENITIC STAINLESS STEEL USING POTENTIOSTATIC PULSE TEST

不锈钢在一定温度范围内经热处理敏化，在晶界附近形成贫铬区，引起晶间腐蚀．本文采用恒电位脉冲技术对奥氏体不锈钢的敏化进行检测，并讨论了该法检测敏化的最佳实验条件．与常用的双环ＥＰＲ法相比较，恒电位脉冲法具有测定速度快、对试样损伤小、测定结果更准确等特点．根据扫描电子显微镜（ＳＥＭ）的观察，敏化度较高的不锈钢电极，经过双环ＥＰＲ实验后在电极表面发生较严重的孔蚀，这可能就是导致ＥＰＲ法测定常会出现偏差的原因；而经恒电位脉冲法实验后的同类电极，则未发现明显的孔蚀现象，从而保证了检测方法的准确性．

ne of the main reasons for intergranular corrosion of austenitic stainless steel is the presence of chromium depleted zones at grain boundaries due to sensitization,which is caused by heating in a certain temperature range. In this paper, potentiostatic pulse test(PPT) has been used to detect the sensitisation of austenitic stainless steel.Compared with the convertional EPR test,the PPT test has some adVantages.It can be conducted at higher speed and with less damage to the specimen,ate.According to SEM morphologies,pitting attack is noticed on the surfaCe of the specimen after EPR test.On the contrary,PPT doesn't show up pitting attack.So PPT is a more specific method for detering sensitization than EPR.