17-4PH不锈钢长期时效对电化学腐蚀行为的影响

Effect of Long-Term Aging on Electrochemical Corrosive Behavior of 17-4PH Stainless Steel

采用恒电位阳极极化法研究了17-4PH不锈钢经长期时效后试样分别在(0.5 mol/LH2SO4+1%NaCl)溶液和1%NaCl溶液中的腐蚀行为。结果表明:17-4PH不锈钢经时效处理后点蚀电位负移,钝化膜保护性下降,材料耐蚀性能降低。17-4PH不锈钢在含有Cl-的H2SO4溶液中能发生钝化,并有较宽的钝化区域,而在1%NaCl溶液中不能形成钝化膜,Cl-对试样有严重的点蚀现象。阳极极化曲线显示,17-4PH不锈钢随着时效时间的延长耐蚀性降低,主要是由于时效处理使第二相沿晶界析出、材料组织发生改变所致。

The corrosion and electrochemical behavior of long-term aging on 17-4PH stainless steel in different solutions has been measured by electrochemical methods.The solutions consisted of chlorine ion sulphuric acid and neutral.Electrochemical potention dynamic reactivation test.The polarization curves re-sults demonstrate that the pitting potential of 17-4PH stainless steel shifted negatively and the protection per-formance of the passive film decreased after aging treatment.The decline of corrosion resistance of aged specimens,and with the age time prolonging corrosion inhibitors is decline the sulphuric acid can control the pit corrosion of 17-4PH stainless steel because the vitriol（S） can hold back the Cl-,The anodic polarization curves illustrate that 17-4PH stainless steel can passive in 1% NaCl sulphuric acid,while in 1% NaCl neutral the passivity is deteriorated due to Cl-ion participate in electrochemical corrosion,accelerate the localized corrosion,destroy passivation and induce pit corrosion to the stainless steel.The decline of corrosion resis-tance of aged specimens was due to the precipitation of the second2 phase along grain boundaries and the transformation of microstructure.