Abstract
The corrosion behavior of austenitic Fe–Mn–Al–Cr–C twinning-induced plasticity (TWIP) and microband-induced plasticity (MBIP) steels with different alloying elements ranging from 22.6–30 wt.% Mn, 5.2–8.5 wt.% Al, 3.1–5.1 wt.% Cr, to 0.68–1.0 wt.% C was studied in 3.5 wt.% NaCl (pH 7) and 10 wt.% NaOH (pH 14) solutions. The results obtained using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques, alongside optical microscopy analysis, revealed pitting as the dominant corrosion mechanism in high-Mn TWIP steels. An X-ray diffraction analysis of the surface revealed that the main corrosion products were hematite (Fe2O3), braunite (Mn2O3), and hausmannite (Mn3O4), and binary oxide spinels were also identified, such as galaxite (MnAl2O4) and jacobsite (MnFe2O4). This is due to the higher dissolution rate of Fe and Mn, which present a more active redox potential. In addition, a protective Al2O3 passive film was also revealed, showing enhanced corrosion protection. The highest corrosion susceptibility in both electrolytes was exhibited by the MBIP steel (30 wt.% Mn). Pitting corrosion was observed in both chloride and alkaline solutions.
Highlights
Accepted: 12 January 2021A single austenite phase steel that is stable at room temperature (RT) whose deformation mechanism, defined by the stacking fault energy (SFE), consists of the gliding of individual dislocations is known as twinning-induced plasticity (TWIP) steel [1,2,3,4,5].the transformation of these twins can lead to local inhomogeneity, limiting the range of applications due to their increased susceptibility to hydrogen embrittlement [6,7].the high content of Mn in these alloys severely impacts the corrosion performance due to the high dissolution rates observed for Mn [8]
The transformation of these twins can lead to local inhomogeneity, limiting the range of applications due to their increased susceptibility to hydrogen embrittlement [6,7]
The high content of Mn in these alloys severely impacts the corrosion performance due to the high dissolution rates observed for Mn [8]
Summary
Accepted: 12 January 2021A single austenite phase steel that is stable at room temperature (RT) whose deformation mechanism, defined by the stacking fault energy (SFE), consists of the gliding of individual dislocations is known as twinning-induced plasticity (TWIP) steel [1,2,3,4,5].the transformation of these twins can lead to local inhomogeneity, limiting the range of applications due to their increased susceptibility to hydrogen embrittlement [6,7].the high content of Mn in these alloys severely impacts the corrosion performance due to the high dissolution rates observed for Mn [8]. A single austenite phase steel that is stable at room temperature (RT) whose deformation mechanism, defined by the stacking fault energy (SFE), consists of the gliding of individual dislocations is known as twinning-induced plasticity (TWIP) steel [1,2,3,4,5]. The transformation of these twins can lead to local inhomogeneity, limiting the range of applications due to their increased susceptibility to hydrogen embrittlement [6,7]. Microbands consisting of geometrically necessary dislocations led to a high total dislocation density state during deformation, resulting in continuous strain hardening. This microband-induced plasticity (MBIP) is the origin of the enhanced mechanical properties of the steel [9,10]
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