Local Probe Techniques for Hydrogen Measurement in Ultra-High Strength Steels

Schaller, Rebecca

doi:10.18130/v3zc62

Cited by 2 publications

(2 citation statements)

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“…Three pin samples were exposed under a 0.4 μL droplet of 4 M NaCl with 0.1 mM, 1 mM, and 10 mM Na 2 CrO 4 for 62 h. The electrolyte concentrations supplied by the droplet on the surface of the pin equilibrated to the droplet's equilibrium concentration of 0.5 M NaCl at 98% RH. 37 The steel rivet was removed and ex situ x-ray tomography was performed with an XRadia MicroXCT-200 † at 10× magnification and 80 kV voltage. The voxel size was 4.2 × 4.2 × 4.2 with 3 μm resolution.…”

Section: Methodsmentioning

confidence: 99%

Effect of Soluble Chromate Inhibitor on the Macro- and Meso-Scale Damage Morphology and Electrochemical Corrosion Behavior of AA7050-T7451 Coupled to Type 316 Stainless Steel

RaflaVeronica

ScullyJohn

2019

CORROSION

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The damage morphology on AA7050-T7451 plate in chromate-containing environments was studied in a simulated fastener-plate arrangement utilizing x-ray tomography. Constant potential holds near the galvanic couple potential provided additional characterization of the damage morphologies. Exposures were conducted in NaCl with the addition of three different chromate concentrations of 0.1 mM, 1 mM, and 10 mM Na 2 CrO 4 . Both x-ray tomography of fastener-plate arrangements and supplemental potentiostatic polarization of planar electrodes showed that the density of local corrosion sites was significantly reduced with the addition of soluble chromate. However, aggressive conditions such as galvanic coupling led to surviving local corrosion sites that were 30 to 40 times deeper in concentrated chromate environments relative to chromate-free environments. To understand these findings, the effect of chromate on the anodic kinetics of AA7050-T7451 and Al-Zn-Mg-Zr (Cu-free 7000), and on the cathodic oxygen reduction reaction (ORR) kinetics of Type 316 stainless steel, pure Cu, Cu replated on AA7050-T74751, and Al 2 CuMg (S phase) were subsequently investigated. Sodium chromate reduced ORR cathodic kinetics by at least one order of magnitude on Type 316 stainless steel and S phase and by less than one order of magnitude on pure Cu. However, additions of sodium chromate did not inhibit ORR cathodic kinetics on AA7050-T7451 when Cu was replated prior to cathodic tests in chromate-containing solutions. In 0.5 M NaCl environments, pitting potentials were raised on AA7050-T7451 upon the addition of chromate and S-phase dissolution was inhibited. These results support the notion that fastener-plate pit density can be reduced by chromate but that the anodic reaction rates in surviving deep localized corrosion sites are not reduced due to a variety of factors that are discussed. Ramifications toward fatigue initiation are discussed.

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Section: Methodsmentioning

confidence: 99%

Effect of Soluble Chromate Inhibitor on the Macro- and Meso-Scale Damage Morphology and Electrochemical Corrosion Behavior of AA7050-T7451 Coupled to Type 316 Stainless Steel

RaflaVeronica

ScullyJohn

2019

CORROSION

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“…21,28 Enhancement of the environmental cracking kinetics is widely attributed to hydrogen embrittlement (HE). 24 Recent research on Custom 465, a precipitation-hardened martensitic stainless-steel based on the Fe-Cr-Ni system, quantified and analyzed the corrosion and H-uptake behavior, 29,30 the pit-to-fatigue crack transition, the short-crack growth and long-crack growth behavior, 13 and the stress-corrosion cracking behavior. 21,28 Critically, a time-dependent intergranular (IG) fracture process was observed at stress intensity ranges (ΔK) below the threshold value (ΔK TH ) during fracture mechanics-based fatigue testing in high [Cl − ] environments.…”

Section: Introductionmentioning

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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Local Probe Techniques for Hydrogen Measurement in Ultra-High Strength Steels

Cited by 2 publications

References 0 publications

Effect of Soluble Chromate Inhibitor on the Macro- and Meso-Scale Damage Morphology and Electrochemical Corrosion Behavior of AA7050-T7451 Coupled to Type 316 Stainless Steel

Effect of Soluble Chromate Inhibitor on the Macro- and Meso-Scale Damage Morphology and Electrochemical Corrosion Behavior of AA7050-T7451 Coupled to Type 316 Stainless Steel

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

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