Effect of Thermo-Mechanical Processing on the Corrosion Behavior of Fe−30Mn−5Al−0.5C TWIP Steel

Ulises Martin,David M Bastidas,Juan Bosch,Jacob Ress

doi:10.3390/app10249104

Ulises Martin, David M Bastidas + Show 2 more

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https://doi.org/10.3390/app10249104

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Journal: Applied sciences	Publication Date: Dec 19, 2020
Citations: 7	License type: CC BY 4.0

Affiliation: University of Akron

Abstract

Electrochemical corrosion of thermo-mechanically processed (TMP) and recrystallized Fe−30Mn−5Al−0.5C twinning-induced plasticity (TWIP) steels containing 30 wt.% Mn was studied in a 1.0 wt.% NaCl electrolyte solution. The alkaline nature of the corrosion products containing manganese oxide (MnO) increases the dissolution kinetics of the TWIP steel in acid media, obtaining Mn2+ cations in solution, and producing the hydrogen evolution reaction (HER). X-ray photoelectron spectroscopy (XPS) surface analysis revealed an increased Al2O3 content of 91% in the passive layer of the recrystallized TWIP steel specimen, while in contrast only a 43% Al2O3 was found on the TMP specimen. Additionally, the chemical composition of the surface oxide layer as well as the TWIP alloy microstructure was analyzed by optical microscopy (OM) and scanning electron microscopy (SEM). The results indicate an enhanced corrosion attack for the TMP high-Mn TWIP steel.

Highlights

In order to stabilize the austenitic phase in a twinning-induced plasticity (TWIP) steel at room temperature (RT), a Mn content higher than 27 wt.% is required [1,2,3,4]
Recrystallized TWIP steel specimens showed homogeneous monophasic austenite microstructure consisting of equiaxial grains with the presence of recrystallization twins
Electrochemical measurements indicated that the thermo-mechanical processing (TMP) TWIP steel presented lower corrosion resistance than the recrystallized specimens

Summary

Introduction

In order to stabilize the austenitic phase in a twinning-induced plasticity (TWIP) steel at room temperature (RT), a Mn content higher than 27 wt.% is required [1,2,3,4]. Increased C content promote the formation of carbides (Fe3 C and Mn3 C) [6,7,8]. Depending on the magnitude of the SFE, different phase transformation processes can be promoted. Martensitic transformation is favored for SFE values below 12 mJ/m2 ; predominant twinning and gliding dislocation mechanisms are found between 12 and 35 mJ/m2 ; and above 35 mJ/m2 dislocation glide is the dominant deformation mechanism [11,12,13]

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