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

2020 ◽  
Vol 10 (24) ◽  
pp. 9104
Author(s):  
Ulises Martin ◽  
Jacob Ress ◽  
Juan Bosch ◽  
David M. Bastidas
Keyword(s):  
Photoelectron Spectroscopy ◽  
Twip Steel ◽  
Electrochemical Corrosion ◽  
Dissolution Kinetics ◽  
Steel Specimen ◽  
Passive Layer ◽  
Al2o3 Content ◽  
Surface Oxide Layer ◽  
Acid Media ◽  
Twip Steels

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.

Electrochemical corrosion study of Sn–XAg–0.5Cu alloys in 3.5% NaCl solution

2007 ◽  
Vol 22 (9) ◽  
pp. 2573-2581 ◽  
Author(s):  
Udit Surya Mohanty ◽  
Kwang-Lung Lin
Keyword(s):  
Photoelectron Spectroscopy ◽  
Electrochemical Corrosion ◽  
Corrosion Current ◽  
Passive Layer ◽  
Anode Surface ◽  
Nacl Solution ◽  
Breakdown Potential ◽  
Passive Transition ◽  
Electrochemical Corrosion Behavior ◽  
And Shifts

The electrochemical corrosion behavior of Sn–XAg–0.5Cu alloys in 3.5% NaCl solution was examined using potentiodynamic polarization techniques. The Ag content in the alloy was varied from 1 to 4 wt%. The polarization curves obtained for the alloys show an active–passive transition followed by a transpassive region. Sn–XAg–0.5Cu alloys with higher Ag content (>2 wt%) show a strong tendency toward passivation. The passivation behavior has been ascribed to the presence of both SnO and SnO2on the anode surface. Increase in Ag content from 1 to 4 wt% results in a decrease in the corrosion-current density (Icorr) and linear polarization resistance (LPR) of the alloy. Nevertheless, the corrosion potential (Ecorr) shifts toward negative values, and a decrease in corrosion rate is observed. The presence of Cl−ion initiates pitting and is responsible for the rupture of the passive layer at a certain breakdown potential. The breakdown potential (EBR) decreases and shifts toward more noble values with increase in Ag content in the alloy. Surface analyses by x-ray photoelectron spectroscopy (XPS) and Auger depth profile studies confirmed the formation of both Sn(II) and Sn(IV) oxides in the passive layer.

Structure and Resistance to Electrochemical Corrosion of NiTi Alloy

2013 ◽  
Vol 203-204 ◽  
pp. 335-338 ◽  
Author(s):  
Bożena Łosiewicz ◽  
Magdalena Popczyk ◽  
Tomasz Goryczka ◽  
Józef Lelątko ◽  
Agnieszka Smołka ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Niti Alloy ◽  
Electrochemical Corrosion ◽  
High Resolution Electron Microscopy ◽  
Potential Method ◽  
Passive Layer ◽  
Open Circuit ◽  
Experimental Conditions ◽  
Electrochemical Tests ◽  
Reflectivity Method

The NiTi alloy (50.6 at.% Ni) passivated for 30 min at 130°C by autoclaving has been studied towards corrosion resistance in aqueous solutions of 3% NaCl, 0.1 M H2SO4, 1 M H2SO4 and HBSS. Structure and thickness of the passive layer (TiO2, rutile) were examined by X-ray reflectivity method and high resolution electron microscopy. Corrosion behavior of this oxide layer was investigated by open circuit potential method and polarization curves. It was found that the corrosion resistance of the passivated NiTi alloy is strongly dependent on the type of corrosive environment. The higher corrosion resistance of the tested samples was revealed in sulfate solutions as compared to chloride ones. The highest resistance to electrochemical corrosion of the NiTi alloy was observed in 0.1 M H2SO4 solution. Susceptibility to pitting corrosion of the tested samples was observed which increased with the concentration rise of chlorine anions in solution. Electrochemical tests for 316L stainless steel carried out under the same experimental conditions revealed a weaker corrosion resistance in all solutions as compared to the highly corrosion resistant NiTi alloy.

On the Utility of Crystal Plasticity Modeling to Uncover the Individual Roles of Microdeformation Mechanisms on the Work Hardening Response of Fe-23Mn-0.5C TWIP Steel in the Presence of Hydrogen

2018 ◽  
Vol 140 (3) ◽  
Author(s):  
B. Bal ◽  
M. Koyama ◽  
D. Canadinc ◽  
G. Gerstein ◽  
H. J. Maier ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Hydrogen Embrittlement ◽  
Twip Steel ◽  
Strain Response ◽  
Deformation Response ◽  
Self Consistent ◽  
Twip Steels ◽  
Simulation Results ◽  
The Individual ◽  
Experimental Findings

This paper presents a combined experimental and theoretical analysis focusing on the individual roles of microdeformation mechanisms that are simultaneously active during the deformation of twinning-induced plasticity (TWIP) steels in the presence of hydrogen. Deformation responses of hydrogen-free and hydrogen-charged TWIP steels were examined with the aid of thorough electron microscopy. Specifically, hydrogen charging promoted twinning over slip–twin interactions and reduced ductility. Based on the experimental findings, a mechanism-based microscale fracture model was proposed, and incorporated into a visco-plastic self-consistent (VPSC) model to account for the stress–strain response in the presence of hydrogen. In addition, slip-twin and slip–grain boundary interactions in TWIP steels were also incorporated into VPSC, in order to capture the deformation response of the material in the presence of hydrogen. The simulation results not only verify the success of the proposed hydrogen embrittlement (HE) mechanism for TWIP steels, but also open a venue for the utility of these superior materials in the presence of hydrogen.

Heat Input Effect on the Microstructure of Twinning-Induced Plasticity (TWIP) Steel Welded Joints Through the GTAW Process

MRS Advances ◽  
2018 ◽  
Vol 3 (64) ◽  
pp. 3949-3956
Author(s):  
H. Hernández-Belmontes ◽  
I. Mejía ◽  
V. García-García ◽  
C. Maldonado
Keyword(s):  
Phase Transformations ◽  
Heat Input ◽  
Twip Steel ◽  
Research Work ◽  
Second Phase ◽  
Current Electrode ◽  
Weld Joints ◽  
Average Grain Size ◽  
Gtaw Process ◽  
Twip Steels

ABSTRACTHigh-Mn Twinning Induced Plasticity (TWIP) steels are an excellent alternative in the design of structural components for the automotive industry. The TWIP steels application allows weight reduction, maintaining the performance of vehicles. Nowadays the research works focused on TWIP steel weldability are relative scarce. It is well-known that weldability is one of the main limitations for industrial application of TWIP steel. The main goal of this research work was studied the effect of heat input on the microstructural changes generated in a TWIP steel microalloyed with Ti. A pair of welds were performed through Gas Tungsten Arc Welding (GTAW) process. The GTAW process was carried out without filler material, using Direc Current Electrode Negative (DCEN), tungsten electrode EWTh-2 and Ar as shielding gas. The microstructure and average grain size in the fusion (FZ) and heat affected zone (HAZ) were determined by light optical metallography (LOM). Elements segregation in the FZ was evaluated using point and elemental mapping chemical analysis (EPMA) by Scanning Electron Microscopy and Electron Dispersive Spectroscopy (SEM-EDS). Phase transformations were evaluated using X-ray diffraction (XRD). Finally, the hardness were measured by means of Vickers microhardness testing (HV500). The results show that the FZ is characterized by a dendritic solidification pattern. Meanwhile, the HAZ presented equiaxed grains in both weld joints. On the other hand, the TWIP-Ti steel weldments did not present austenite phase transformations. Nevertheless, the FZ exhibited variations in the chemical elements distribution (Mn, Al, Si and C), which were higher as the heat input increases. Finally, the heat input reduced the microhardness of TWIP-Ti steel weld joints. Although post-welding hardness recovery was detected, which is associated with precipitation of Ti second-phase particles.

The Mechanical and Deformation Behavior of TWIP Steel Prepared by Directional Solidification

2014 ◽  
Vol 783-786 ◽  
pp. 761-765 ◽  
Author(s):  
Dan Wang ◽  
Kun Wang ◽  
Zi Mu Shi ◽  
Fu Sheng Han
Keyword(s):  
Mechanical Properties ◽  
Strain Hardening ◽  
Twip Steel ◽  
True Strain ◽  
Longitudinal Direction ◽  
True Stress ◽  
Grain Structure ◽  
Directionally Solidified ◽  
Twip Steels ◽  
Columnar Grain

A directionally solidified TWIP steel (Fe-25Mn-2.5Al-2.5Si) was prepared by liquid metal cooling technology. The microstructure and mechanical behavior were examined and compared with usually solidified samples. The directionally solidified TWIP steel shows a typical columnar grain structure, and the maximum true stress and true strain along the longitudinal direction of the sample are 1060MPa and 71% respectively. As a comparison, the usually solidified samples shows an equiaxed grain microstructure with the maximum true stress and true strain of only 994MPa and 58%, respectively. Moreover, the two solidification modes also lead to very different strain hardening behavior, particularly in the changes of strain hardening rate with strain. This suggests that the grain boundary plays a key role in the mechanical properties of TWIP steels, and changing the grain boundaries can be effective to improve the comprehensive mechanical properties of TWIP steels.

scholarly journals Direct Acid Leaching of Sphalerite: An Approach Comparative and Kinetics Analysis

Minerals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 359
Author(s):  
Nallely G. Picazo-Rodríguez ◽  
Ma. de Jesus Soria-Aguilar ◽  
Antonia Martínez-Luévanos ◽  
Isaias Almaguer-Guzmán ◽  
Josue Chaidez-Félix ◽  
...  
Keyword(s):  
Acid Leaching ◽  
Dissolution Kinetics ◽  
Pilot Scale ◽  
Influential Factors ◽  
Acid Media ◽  
Rate Limiting Step ◽  
Leaching Solution ◽  
Direct Leaching ◽  
Media Lab ◽  
Rate Limiting

The present work reports the direct leaching of zinc from a sphalerite concentrate in acid media. Lab-scale and pilot-scale experiments were conducted in atmospheric-pressure and low-pressure reactors, respectively. Leaching of zinc and precipitation of iron was achieved in the same stage using different reagents like Fe3+, O2, O3, and Fe2+ (which is continuously oxidized in the leaching solution by H2O2 and O2). The highest percentage of zinc extraction (96%) was obtained in pilot-scale experiments using H2SO4, Fe2+, and O2. Experimental results were compared with those of other researchers to provide a better understanding of the factors influencing the dissolution of zinc. In the first instance, it was determined from analysis of variance that leaching time and the use of an oxidant agent (O2 or O3) were the most influential factors during the direct leaching of zinc from the sphalerite concentrate. Kinetic models were also evaluated to determine the rate-limiting step of the sphalerite leaching; it was concluded that the type of the sulfur layer formed in the residue (porous or non-porous) depends on the type of the oxidant used in the leaching media, which determines the dissolution kinetics of zinc.

Oxidation of Planar and Plasmonic Ag Surfaces by Exposure to O2/Ar Plasma for Organic Optoelectronic Applications

MRS Advances ◽  
2016 ◽  
Vol 1 (14) ◽  
pp. 943-948 ◽  
Author(s):  
Christopher E. Petoukhoff ◽  
Catherine Antonick ◽  
Bala Murali Krishna M. ◽  
Keshav M. Dani ◽  
Deirdre M. O'Carroll
Keyword(s):  
Exposure Time ◽  
Photoelectron Spectroscopy ◽  
Dark Field ◽  
Binding Energies ◽  
Surface Oxide Layer ◽  
Pump Probe ◽  
Dark Field Microscopy ◽  
Ar Plasma ◽  
Organic Optoelectronic ◽  
Ultrathin Layer

ABSTRACTHere, we expose planar and plasmonic Ag surfaces to a low-power O2/Ar plasma to form an ultrathin surface oxide layer. We study the chemical state and morphology of the plasma-treated Ag surfaces using X-ray photoelectron spectroscopy, scanning electron microscopy, and dark-field microscopy. We observe the formation of an ultrathin layer (< 10 nm) composed of both AgOx and Ag2CO3 for a plasma exposure time of 1 s by investigating shifts in the Ag3d, O1s, and C1s core level binding energies. For an exposure time of 1 s, the surface structure of the planar and plasmonic Ag surfaces remains unchanged. For exposure times of 5 - 30 s, the planar Ag surfaces become porous and exhibit increased surface roughness. We demonstrate that the plasma-treated planar and plasmonic Ag surfaces lead to improvements in the excited-state population of a polymer:fullerene coating through ultrafast pump-probe reflectometry.

Surface Study of Ti3Al and Ti3Al-11Nb, TiAl and TiAl-2Cr by X-Ray Photoelectron Spectroscopy

2003 ◽  
Vol 17 (08n09) ◽  
pp. 1711-1716 ◽  
Author(s):  
J. Lee ◽  
W. Gao ◽  
M. Hodgson
Keyword(s):  
Photoelectron Spectroscopy ◽  
High Temperature Oxidation ◽  
Electrochemical Corrosion ◽  
Atomic Ratio ◽  
Bulk Materials ◽  
Temperature Oxidation ◽  
X Ray ◽  
Cr Addition ◽  
Electrochemical Corrosion Resistance ◽  
Main Component

Oxide films formed on intermetallics Ti 3 Al , Ti 3 Al -11at.%Nb, TiAl and TiAl-2at.%Cr were studied by X-Ray Photoelectron Spectroscopy (XPS). An addition of 11at%Nb to Ti 3 Al increases the Ti:Al atomic ratio on the surface from 2.8:1 to 20:1. This may explain the better electrochemical corrosion resistance of Ti 3 Al -11Nb than Ti 3 Al . Meanwhile, an addition of 2at.%Cr to TiAl decreases the Ti atomic percentage from 11.8 to 9.5. The Ti:Al atomic ratio changes from 1:0.2 to 1:1.8. The Cr addition enhances the formation of an Al-enriched passive film, which may be the reason for the improved TiAl high temperature oxidation resistance. TiO 2 is the main component of the top oxide layers formed on the intermetallics of Ti 3 Al , Ti 3 Al -11Nb and TiAl. In contrast the top layer of TiAl-2Cr is mainly Al 2 O 3. XPS results show that the compositions are quite different between the bulk materials and the top oxide layer on these intermetallics.

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