The Influence of Magnetization on Corrosion in Pipeline Steels

2006 ◽  
Author(s):  
Joshua E. Jackson ◽  
Angelique N. Lasseigne-Jackson ◽  
Francisco J. Sanchez ◽  
David L. Olson ◽  
Brajendra Mishra
Keyword(s):  
Magnetic Field ◽  
Hydrogen Content ◽  
Applied Magnetic Field ◽  
Cold Work ◽  
Strong Increase ◽  
Surface Layers ◽  
Electronic Spin ◽  
Thermodynamic Effect ◽  
Hydrogen Induced Cracking ◽  
Anodic Reactions

Laboratory measurements have shown a strong increase on the hydrogen content in steel after electrochemical hydrogen charging with a two Tesla applied magnetic field and a serious increase in hydrogen-induced cracking and pitting. Cold work combining with the effect of applied magnetic field creates a material more crack sensitive to increased hydrogen content. A derivation based on the use of the Helmholtz Free Energy is applied to examine the thermodynamic effect of magnetization on hydrogen content. The effect of magnetization on the electronic spin configurations, magnetostriction (directional strain induced in steel from an applied magnetic field), and interstitial solute-induced strain are considered. A possible kinetic model for enhanced hydrogen ion pickup and corrosion based on surface effects associated with the Gouy-Chapman Layer and the Helmholtz Double Layer is examined. Disturbance of these layers acts to enhance hydrogen transport to the surface. The high applied and remanent magnetic fields and large cathodic protection currents returning in the pipe simultaneously may disturb these surface layers, resulting in enhancement of both cathodic and anodic reactions.

scholarly journals Ultrasonic Study of Thermal hysteresis in Helical antiferromagnetic Dy

2018 ◽  
Vol 57 (2) ◽  
pp. 241-245 ◽  
Author(s):  
Iu. Liubimova ◽  
K. Sapozhnikov ◽  
V. Nikolaev ◽  
M.-Li Corró ◽  
S. Kustov
Keyword(s):  
Magnetic Field ◽  
Heating Rate ◽  
Applied Magnetic Field ◽  
Domain Walls ◽  
Thermal Hysteresis ◽  
Lattice Defects ◽  
Ferromagnetic Phase ◽  
Strong Increase ◽  
Ultrasonic Absorption ◽  
Thermal Cycles

Abstract High-resolution ultrasonic mechanical spectroscopy technique has been used to study the nature and dynamics of lattice defects and magnetic domain walls in the helical-type antiferromagnetic phase during thermal cycling of polycrystalline Dy samples between 80 and 210K. Effects of the lowest temperature of thermal cycles, applied magnetic field and cooling/ heating rate on the ultrasonic absorption and Young´s modulus have been investigated. A strong influence of cooling/heating rate on the ultrasonic absorption is found over the temperature range between the Néel temperature, ca. 178K, and approximately 145K, confirming the existence of a new category of magnetomechanical damping - transitory ultrasonic absorption related to translational motion of domain walls. A strong increase of the ultrasonic absorption below approximately 140K is attributed to the formation of nuclei of ferromagnetic phase, presumably stabilized by such lattice defects as dislocations. The effect of applied magnetic field on ultrasonic absorption also emerges below 140K and is ascribed to the appearance of the net magnetization due to ferromagnetic nuclei. We argue that these nuclei are responsible for the controversial thermal hysteresis of elastic and anelastic properties, which is strongly promoted by decreasing the temperature of thermal cycles.

The Effect of Magnetic Fields on Corrosion in Pipeline Steel

2007 ◽  
Author(s):  
Joshua E. Jackson ◽  
Angelique N. Lasseigne-Jackson ◽  
David L. Olson ◽  
Brajendra Mishra ◽  
Meredith S. Heilig ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Hydrogen Content ◽  
Electrochemical Impedance ◽  
Pipeline Steel ◽  
Cold Work ◽  
Passive Layer ◽  
Laboratory Research ◽  
Electromagnetic Current

Measurements performed in earlier research have indicated a strong effect of magnetization on hydrogen content (thermodynamics) as well as cracking, and pitting (kinetics) in pipeline steels as described in Sanchez (2005) and Sanchez et al. (2005). The effect of cold work, further increasing hydrogen content, cracking, and pitting, was also assessed. Theoretical descriptions of both thermodynamic and kinetic interpretations of the observed effect is described and correlated to observed results. There are two ways that electromagnetic current influences corrosion: (1) D/C currents (under applied or Remanent magnetic fields) and A/C electric currents (which create electromagnetic fields through Lenz’s Law) may influence magnetocorrosion as described in this paper, and (2) A/C currents also have the potential to strip the protective passive layer from materials and greatly accelerate corrosion. Electrochemical charging is currently being performed at varied magnetic field strengths to assess the nature of the observed influence of magnetization on both hydrogen content (thermodynamic) and cracking/pitting (kinetic), including the role of controlled-roll cold working. Naval and maritime use of A/C and D/C electric-powered systems including propulsion drives, servos, and controls, is increasing rapidly in sea-going operation and potential for stray currents is an increasing risk. Magnetic flux leakage inspection, using saturating magnetic fields, is widely used for reliable and accurate inspection of pipeline corrosion and wall thickness. Previous laboratory research shows a significant increase in both pipeline steel hydrogen content in steel and pitting and cracking after electrochemical hydrogen charging under an applied two Tesla magnetic field. Cold work was observed to further increase the observed effects. The thermodynamic auxiliary functions, using a derivation of Helmholtz free energy, are examined to assess the thermodynamic effects of magnetization on hydrogen content. The effect of magnetization on the thermodynamics of electron spin configurations, interstitial solute-induced strain, magnetostriction (directional strain induced in steel from an applied magnetic field) are considered. Kinetic interpretations of possible interactions with the Helmholtz Double (capacitor-like) Layer and the Gouy-Chapman (diffuse) layer that may lead to increased diffusion and thus to hydrogen supersaturation are described. Electrochemical impedance measurements are being performed to assess the influence of applied magnetic fields on the Helmholtz and Gouy-Chapman layers.

scholarly journals Transition from hydrodynamic turbulence to magnetohydrodynamic turbulence in von Kármán flows

2012 ◽  
Vol 693 ◽  
pp. 243-260 ◽  
Author(s):  
Gautier Verhille ◽  
Ruslan Khalilov ◽  
Nicolas Plihon ◽  
Peter Frick ◽  
Jean-François Pinton
Keyword(s):  
Magnetic Field ◽  
Reynolds Number ◽  
Interaction Parameter ◽  
Applied Magnetic Field ◽  
Strong Increase ◽  
Liquid Gallium ◽  
Induced Magnetic Field ◽  
Global Variables ◽  
Von Karman ◽  
Von Kármán

AbstractThe influence of an externally applied magnetic field on flow turbulence is investigated in liquid-gallium von-Kármán (VK) swirling flows. Time-resolved measurements of global variables (such as the flow power consumption) and local recordings of the induced magnetic field are made. From these measurements, an effective Reynolds number is introduced as ${\mathit{Rm}}_{\mathit{eff}} = \mathit{Rm}(1\ensuremath{-} \ensuremath{\alpha} \sqrt{N} )$, so as to take into account the influence of the interaction parameter $N$. This effective magnetic Reynolds number leads to unified scalings for both global variables and the locally induced magnetic field. In addition, when the flow rotation axis is perpendicular to the direction of the applied magnetic field, significant flow and induced magnetic field fluctuations are observed at low interaction parameter values, but corresponding to an Alfvèn speed ${v}_{A} $ of the order of the fluid velocity fluctuations ${u}_{\mathit{rms}} $. This strong increase in the flow fluctuations is attributed to chaotic changes between hydrodynamic and magnetohydrodynamic velocity profiles.

scholarly journals Generation of Reverse Meniscus Flow by Applying An Electromagnetic Brake

2021 ◽  
Author(s):  
Alexander Vakhrushev ◽  
Abdellah Kharicha ◽  
Ebrahim Karimi-Sibaki ◽  
Menghuai Wu ◽  
Andreas Ludwig ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Lorentz Force ◽  
Applied Magnetic Field ◽  
Numerical Study ◽  
Flow Direction ◽  
Experimental Studies ◽  
Submerged Entry Nozzle ◽  
Mean Flow ◽  
Slab Caster ◽  
The Mean

AbstractA numerical study is presented that deals with the flow in the mold of a continuous slab caster under the influence of a DC magnetic field (electromagnetic brakes (EMBrs)). The arrangement and geometry investigated here is based on a series of previous experimental studies carried out at the mini-LIMMCAST facility at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR). The magnetic field models a ruler-type EMBr and is installed in the region of the ports of the submerged entry nozzle (SEN). The current article considers magnet field strengths up to 441 mT, corresponding to a Hartmann number of about 600, and takes the electrical conductivity of the solidified shell into account. The numerical model of the turbulent flow under the applied magnetic field is implemented using the open-source CFD package OpenFOAM®. Our numerical results reveal that a growing magnitude of the applied magnetic field may cause a reversal of the flow direction at the meniscus surface, which is related the formation of a “multiroll” flow pattern in the mold. This phenomenon can be explained as a classical magnetohydrodynamics (MHD) effect: (1) the closure of the induced electric current results not primarily in a braking Lorentz force inside the jet but in an acceleration in regions of previously weak velocities, which initiates the formation of an opposite vortex (OV) close to the mean jet; (2) this vortex develops in size at the expense of the main vortex until it reaches the meniscus surface, where it becomes clearly visible. We also show that an acceleration of the meniscus flow must be expected when the applied magnetic field is smaller than a critical value. This acceleration is due to the transfer of kinetic energy from smaller turbulent structures into the mean flow. A further increase in the EMBr intensity leads to the expected damping of the mean flow and, consequently, to a reduction in the size of the upper roll. These investigations show that the Lorentz force cannot be reduced to a simple damping effect; depending on the field strength, its action is found to be topologically complex.

scholarly journals Stability of nonaxisymmetric ferrofluid flow in rotating cylinders with magnetic field

2005 ◽  
Vol 2005 (23) ◽  
pp. 3727-3737 ◽  
Author(s):  
Jitender Singh ◽  
Renu Bajaj
Keyword(s):  
Magnetic Field ◽  
Applied Magnetic Field ◽  
Critical Value ◽  
Annular Space ◽  
Rotating Cylinders ◽  
The Stability

Effect of an axially applied magnetic field on the stability of a ferrofluid flow in an annular space between two coaxially rotating cylinders with nonaxisymmetric disturbances has been investigated numerically. The critical value of the ratioΩ∗of angular speeds of the two cylinders, at the onset of the first nonaxisymmetric mode of disturbance, has been observed to be affected by the applied magnetic field.

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