A Model of Crack Electrochemistry for Steels in the Active State Based on Mass Transport by Diffusion and Ion Migration

Turnbull, A.; Thomas, J. G. N.

doi:10.1149/1.2124176

Cited by 95 publications

(39 citation statements)

References 8 publications

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“…[54] Crack-tip pH and potential were established for Monel K-500 using the artificial crevice geometry shown in Figure 1, coupled with the scaling-law approach to relate crevice and crack geometry difference. [68][69][70] The cell consisted of: (a) an acrylic bottom plate with six disk specimens embedded and shorted to form a continuous working electrode (WE), (b) a plastic shim to create the crevice gap (G), and (c) an acrylic top plate to form the crevice and hold micro-reference electrodes (REs) for local potential measurement. Monel K-500 specimens (surface area~3 cm 2 ) were polished through 600 grit, degreased with ethanol, and mounted ( Figure 1 The artificial crevice electrochemical cell, where A is a potentiostat, CE is a counter electrode, and B is a multimeter to measure potential of 6-shorted alloy working electrodes (WE) in a crevice of opening-gap (G).…”

Section: E Occluded Crevice Electrochemistry and Local Hydrogen Concmentioning

confidence: 99%

Measurement and Modeling of Hydrogen Environment-Assisted Cracking in Monel K-500

Gangloff

Burns

et al. 2014

Metall Mater Trans A

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Hydrogen environment-assisted cracking (HEAC) of Monel K-500 is quantified using slow-rising stress intensity loading with electrical potential monitoring of small crack propagation and elastoplastic J-integral analysis. For this loading, with concurrent crack tip plastic strain and H accumulation, aged Monel K-500 is susceptible to intergranular HEAC in NaCl solution when cathodically polarized at À800 mV SCE (E A , vs saturated calomel) and lower. Intergranular cracking is eliminated by reduced cathodic polarization more positive than À750 mV SCE . Crack tip diffusible H concentration rises, from near 0 wppm at E A of À765 mV SCE , with increasing cathodic polarization. This behavior is quantified by thermal desorption spectroscopy and barnacle cell measurements of hydrogen solubility vs overpotential for planar electrodes, plus measured-local crevice potential, and pH scaled to the crack tip. Using crack tip H concentration, excellent agreement is demonstrated between measurements and decohesion-based model predictions of the E A dependencies of threshold stress intensity and Stage II growth rate. A critical level of cathodic polarization must be exceeded for HEAC to occur in aged Monel K-500. The damaging-cathodic potential regime likely shifts more negative for quasi-static loading or increasing metallurgical resistance to HEAC.

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Section: E Occluded Crevice Electrochemistry and Local Hydrogen Concmentioning

confidence: 99%

Measurement and Modeling of Hydrogen Environment-Assisted Cracking in Monel K-500

Gangloff

Burns

et al. 2014

Metall Mater Trans A

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“…Finite element method, Galerkin method, 62 is used for space discretization while Backwards differentiation formula (BDF) method 63 is used for the time integration of the governing partial differential Eqs (17,18,21,(24)(25)(26)(27)(28). Triangular Lagrangian mesh elements were chosen to discretize the space.…”

Section: Methodsmentioning

confidence: 99%

“…These numerical models can be divided according to the method in which a moving interface is incorporated in their models. Several steady state 9,10,[13][14][15][16][17][18] and transient state [19][20][21][22][23][24][25][26][27][28] models have been developed over the years that did not allow for changes in the shape and dimensions of the pits/crevices as corrosion proceeds.…”

Section: Introductionmentioning

confidence: 99%

Phase-field model of pitting corrosion kinetics in metallic materials

Ansari

Xiao

et al. 2018

npj Comput Mater

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Pitting corrosion is one of the most destructive forms of corrosion that can lead to catastrophic failure of structures. This study presents a thermodynamically consistent phase field model for the quantitative prediction of the pitting corrosion kinetics in metallic materials. An order parameter is introduced to represent the local physical state of the metal within a metal-electrolyte system. The free energy of the system is described in terms of its metal ion concentration and the order parameter. Both the ion transport in the electrolyte and the electrochemical reactions at the electrolyte/metal interface are explicitly taken into consideration. The temporal evolution of ion concentration profile and the order parameter field is driven by the reduction in the total free energy of the system and is obtained by numerically solving the governing equations. A calibration study is performed to couple the kinetic interface parameter with the corrosion current density to obtain a direct relationship between overpotential and the kinetic interface parameter. The phase field model is validated against the experimental results, and several examples are presented for applications of the phase-field model to understand the corrosion behavior of closely located pits, stressed material, ceramic particles-reinforced steel, and their crystallographic orientation dependence. INTRODUCTIONCorrosion is the gradual destruction of materials (usually metallic materials) via chemical and/or electrochemical reaction with their environment. It costs about 3.1% of the gross domestic product (GDP) in the United States, which is much more than the cost of all natural disasters combined. Localized corrosion, such as pitting corrosion, is one of the most destructive forms of corrosion; it leads to the catastrophic failure of structures and raises both human safety and financial concerns. 1-3 Pitting corrosion of stainless steel usually occurs in two different stages: (1) pit initiation from passive film breakage 4-6 and (2) pit growth. 2,3,[7][8][9][10][11][12] In this study, we focused on the development of a phase-field modeling capability to study pit growth by considering both anodic and cathodic reactions.In the past few decades, great efforts have been made to develop numerical models for pitting corrosion. The moving interface and the electrical double layer at the metal/electrolyte interface are the two challenging problems faced by most of these numerical models. These numerical models can be divided according to the method in which a moving interface is incorporated in their models. Several steady state 9,10,13-18 and transient state 19-28 models have been developed over the years that did not allow for changes in the shape and dimensions of the pits/crevices as corrosion proceeds.Recent advances in numerical techniques, such as the finite element method, the finite volume method, the arbitrary Lagrangian-Eulerian method, the mesh-free method, and the level set method have encouraged researchers to model the evolving morphology...

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“…3. However, abundant evidence supports the development of an aggressive, occluded, high [Cl − ] crack-tip environment (particularly in Cr-containing steels), 27,[43][44][45][46][47] suggesting a secondary influence of increasing bulk chloride content above a critical level necessary for the onset of IG-SCC. Specifically, increasing bulk chloride concentration from 0.6 to 3 M NaCl will have minimal effect due to the development of a constant, occluded crack-tip environment (for H production) and crack-growth limitation by H-diffusion in the process zone.…”

Section: Discussionmentioning

confidence: 99%

The interaction of corrosion fatigue and stress-corrosion cracking in a precipitation-hardened martensitic stainless steel

2017

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Fracture mechanics-based testing was used to quantify the stress-corrosion cracking and corrosion fatigue behavior of a precipitation-hardened martensitic stainless steel (Custom 465-H950) in full immersion chloride-containing environments at two applied electrochemical potentials. A plateau in the cycle-based crack-growth kinetics (da/dN) was observed during fatigue loading at low ΔK and [Cl − ] at and above 0.6 M. Evaluation of the fracture morphology and frequency dependence of this plateau behavior revealed an intergranular fracture surface morphology and constant time-dependent growth rates. These data strongly support a controlling stress-corrosion cracking mechanism occurring well below the established K ISCC for quasi-static loading. Low-amplitude cyclic loading below ΔK TH (i.e., "ripple loads") is hypothesized to enable time-dependent intergranular-stress-corrosion cracking to occur below the K ISCC via mechanical rupturing of the crack-tip film and enhancement of the H embrittlement-based SCC mechanism.

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A Model of Crack Electrochemistry for Steels in the Active State Based on Mass Transport by Diffusion and Ion Migration

Cited by 95 publications

References 8 publications

Measurement and Modeling of Hydrogen Environment-Assisted Cracking in Monel K-500

Measurement and Modeling of Hydrogen Environment-Assisted Cracking in Monel K-500

Phase-field model of pitting corrosion kinetics in metallic materials

The interaction of corrosion fatigue and stress-corrosion cracking in a precipitation-hardened martensitic stainless steel

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