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Use of SECM to study the electrochemical behavior of DIN 1.4575 superferritic stainless steel aged at 475 °C
Author(s) -
Terada M.,
Padilha A. F.,
Simões A. M. P.,
de Melo H. G.,
Costa I.
Publication year - 2009
Publication title -
materials and corrosion
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.487
H-Index - 55
eISSN - 1521-4176
pISSN - 0947-5117
DOI - 10.1002/maco.200905314
Subject(s) - dielectric spectroscopy , materials science , corrosion , electrochemistry , metallurgy , composite material , electrode , chemistry
Abstract In order to lower the excessive costs of metallic prosthesis materials alternatives to Ti and Ti alloys have been searched. In this study, the corrosion resistance of the DIN 1.4575 superferritic stainless steel, either solution annealed or solution annealed and aged at 475 °C for periods varying from 100 to 1080 h, was investigated by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization methods in Hanks' solution. The solution annealed and the aged for 1080 h samples were also tested using scanning electrochemical microscopy (SECM) in a 0.1 mol/L NaCl solution at 25 °C. The EIS results showed that the corrosion resistance of the DIN 1.4575 steel decreases with heat treatment time at 475 °C probably due to alpha prime formation. Besides the diminution of the overall impedance values, the low frequency limit of the Nyquist diagrams show a progressive change from an almost capacitive response to a resistive behavior as the heat treatment time increases. Pitting corrosion resistance also decreased with aging time at 475 °C.