EFFECT OF SO2 ON CORROSION EVOLUTION OF Q235B STEEL IN SIMULATED COASTAL-INDUSTRIAL ATMOSPHERE

Abstract

The atmosphere in many cities along the coastal lines such as Qingdao in China has been polluted with SO2 due to the development of industry, and has been changed to coastal-industrial atmosphere. The corrosion behavior and mechanism of steel in coastal-industrial atmosphere with the co-existence of SO2 and Cl is different from that in the coastal atmosphere containing only Cl or the industrial atmosphere containing only SO2. It is necessary to study the corrosion mechanism of steel in the coastal-industrial atmosphere. However, almost all the atmospheric corrosion data of steels was obtained by the field exposure test, which could not reflect the dependence of SO2 or Cl on the atmospheric corrosion evolution of steels due to the difficulties in controlling the field conditions. So the effect of SO2 on the corrosion evolution of Q235B steel in the simulated coastal-industrial atmospheres was investigated by the dry/wet cyclic corrosion test (CCT), as well as XRD, electrochemical impedance spectroscopy (EIS) and polarization curve measurements. The results indicate that in the initial stage, the SO2 inhibits corrosion of Q235B steel. During the later stage, the corrosion rate of the steel increases with increasing the SO2 concentration to a certain level but further increasing the SO2 concentration contributes to a decreased corrosion rate. Besides, higher SO2 concentration can promote the formation of a-FeOOH while inhibit the formation of g-FeOOH and bFeOOH. Evolution of Q235B steel corrosion rate in the atmosphere with SO2 concentration is due to the *国家自然科学基金项目 51201170和 51131007资助 收到初稿日期: 2013-11-15,收到修改稿日期: 2014-03-13 作者简介:陈文娟,女, 1986年生,博士生 DOI: 10.3724/SP.J.1037.2013.00738