The Influence of environmental factors on the pitting potential of stainless steel

Potentiodynamic scanning method was used to study influence of environmental factors on the pitting potentials of types NHB-1、NHB-3、316L and 304 stainless steel. The changing ranges of temperature、PH and Nacl concentration were 0°-90℃、2-2 and 1%-5%,respectively. The experimenta 1 results showed that below certain temperature(It can be called Eb's as tran-siton temperature) the Eb rapidly decrease with the temperature increase while over this temperature,the Eb slowly decrease with the temperature increase in studied conditional ranges, preferential adsorption of Cl^-、O₂ and H₂O on passivating films can be used to explain this pheiomenon. Increasing NaCl concentration,the Eb tend to decrease. The Eb increase with PH increase in neutral and acid solution.pitting corrosion was not found for the types of NHB-1 and NHB-3 stainless steel at Low temperature and for the types of NHB-1 and 316L stanless steel at PH12.