Influence of Urban Sewage as Recycled Cooling Water on Corrosion Resistance of 316L Stainless Steel

The influences of the concentration of Cl-and NH4+-N in urban sewage as a simulated cooling water and its chemical oxygen demand(COD)and pH value on the corrosion resistance of 316L stainless steel were investigated using electrochemical method(polarization curve measurement).Results showed that the pitting corrosion potential of the stainless steel greatly decreased at a Cl-concentration of 300 mg/L.The increase in the concentration of NH4+-N up to 20 mg/L and above led to a significant decrease in the pitting corrosion potential of the stainless steel.Moreover,the passive current of the stainless steel increased slightly with the increase in the COD,and it sharply rose at a pH above 9.