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

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 results demonstrate that the pitting potential of 17-4PH stainless steel shifted negatively and the protection performance 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 resistance of aged specimens was due to the precipitation of the second2 phase along grain boundaries and the transformation of microstructure.