Electrochemical corrosion behavior of bulk ultra-fine grained Fe-Ni-Cr alloy
(1. Department of Mechanical Engineering, Liaoning Shihua University, Fushun 113001, China;
2. CNOOC Energy Technology and Services–Pipe Engineering Co., Tianjin 300452, China;
3. Department of Mechanical Engineering, Materials Science and Engineering Program, Texas A&M University,
College Station, Texas 77843-3123, USA)
2. CNOOC Energy Technology and Services–Pipe Engineering Co., Tianjin 300452, China;
3. Department of Mechanical Engineering, Materials Science and Engineering Program, Texas A&M University,
College Station, Texas 77843-3123, USA)
Abstract: The corrosion behavior of bulk ultra-fine grained (UFG) Fe-Ni-Cr alloy prepared by equal-channel angular pressing technique was investigated in 0.25 mol/L Na2SO4+0.05 mol/L H2SO4 solution by electrochemical measurements. As compared to the coarse grained (CG) counterpart, the UFG alloy exhibits an acceleration of the active dissolution and a shrunk passive region with a higher passive current. The Mott-Schottky analysis in conjunction with the point defect model indicates that the donor diffusion coefficient in the passive films of the UFG sample increases greatly to one magnitude order higher and the donor density is slightly lower than that of the CG sample.
Key words: stainless steel; Fe-Ni-Cr; polarization; acid corrosion; passivation