Acta Metallurgica Sinica (English Letters) ›› 2010, Vol. 23 ›› Issue (4): 301-311.DOI: 10.11890/1006-7191-104-301

• Research paper • Previous Articles     Next Articles

Electrochemical corrosion behavior of 300M ultra high strength steel in chloride containing environment

Min SUN, Kui XIAO, Chaofang DONG, Xiaogang LI   

  1. Corrosion and Protection Center, School of Material and Engineering, University of Science and Technology Beijing, Beijing 100083, China
  • Received:2010-02-26 Revised:2010-04-23 Online:2010-08-25 Published:2010-08-11
  • Contact: Xiaogang LI

Abstract:

The electrochemical corrosion behavior of 300M ultra high strength steel in chloride containing environment was investigated by potentiodynamic polarization technique, electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM). The results show that uniform corrosion occurs on 300M steel during the electrochemical measurements because no anodic passivation phenomenon is observed on polarization curves within the measurement range. The tests also show that 300M steel is highly susceptible to chloride containing solution, which is characterized by corrosion current density increasing with the addition of chlorides, and corrosion potential shifting towards positive direction and corrosion resistance decreasing, positively suggesting that chloride ions speed up the corrosion rate of 300M steel. Meanwhile corrosion products on the 300M steel surface formed during the salt spray test are too loose and porous to effectively slow down the corrosion rate. Additionally, a schematic structure of uniform corrosion mechanism can explain that 300M steel has better property of stress corrosion cracking (SCC) resistance than stainless steels.

Key words: 300M ultra high strength steel, Electrochemical corrosion, Chloride