Correlative EBSD and SKPFM characterisation of microstructure development to assist determination of corrosion propensity in grade 2205 duplex stainless steel

Örnek, Cem; Engelberg, Dirk

doi:10.1007/s10853-015-9501-3

Cited by 65 publications

(58 citation statements)

References 67 publications

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“…The magnitude of the Volta potential difference between dissimilar microstructural constituents is a quantitative measure for microgalvanic corrosion [35,36,47,49,50,52,[57][58][59][60][61][62]. Therefore, respectively.…”

Section: Discussionmentioning

confidence: 99%

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Volta Potential Evolution of Intermetallics in Aluminum Alloy Microstructure Under Thin Aqueous Adlayers: A combined DFT and Experimental Study

et al. 2018

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In this work, first-principle density functional theory (DFT) was used to calculate the work function and Volta potential differences between aluminum alloy matrix and two intermetallic phases (Mg 2 Si and Al 2 Cu) with varying surface terminations as a function of adhering monolayers (ML) of water. The calculated data were compared with experimental local Volta potential data obtained by the scanning Kelvin probe force microscopy (SKPFM) on a commercial aluminum alloy AA6063-T5 in atmospheric environments with varying relative humidity (RH). The calculations suggest that the surface termination has a major effect on the magnitude and polarity of the Volta potential of both intermetallic phases (IMP's). The Volta potential difference between the IMP's and the aluminum matrix decreases when the surface is gradually covered by water molecules, and may further change as a function of adhering ML's of water. This can lead to nobility inversions of the IMP's relative to the aluminum matrix. The measured Volta potential difference between both IMP's and their neighboring matrix is dependent on RH. Natural oxidation in ambient indoor air for 2 months led to a nobility inversion of the IMP's with respect to the aluminum matrix, with the intermetallics showing anodic nature already in dry condition. The anodic nature of Al 2 Cu remained with the introduction of RH, whereas Mg 2 Si became cathodic at high RH, presumably due to de-alloying of Mg and oxide dissolution. The DFT calculations predicted an anodic character of both IMP's in reference to the oxidized aluminum matrix, being in good agreement with the SKPFM data. The DFT and SKPFM data were discussed in light of understanding localized corrosion of aluminum alloys under conditions akin to atmospheric exposure.

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Section: Discussionmentioning

confidence: 99%

“…Potential line profiles were sectioned from selected sites and plotted in potential vs. distance charts, from which the Volta potential difference between the IMP and the alloy matrix was obtained. Interpretation of SKPFM data was done in accordance to previous works [49][50][51][52].…”

Section: Volta Potential Microscopymentioning

confidence: 99%

Volta Potential Evolution of Intermetallics in Aluminum Alloy Microstructure Under Thin Aqueous Adlayers: A combined DFT and Experimental Study

et al. 2018

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“…The atmospheric corrosion performance of DSS has been studied as a function of strain, stress, and deposition density, and so far, a good understanding of the relationship of ferrite and austenite in DSS microstructures has been established. [28][29][30][31][32][33][34][35][36][37] However, CRs and SCC growth rates, in particular under atmospheric exposure conditions, have not been reported yet.…”

Section: Introductionmentioning

confidence: 99%

Time-dependent in situ measurement of atmospheric corrosion rates of duplex stainless steel wires

et al. 2018

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Corrosion rates of strained grade UNS S32202 (2202) and UNS S32205 (2205) duplex stainless steel wires have been measured, in situ, using time-lapse X-ray computed tomography. Exposures to chloride-containing (MgCl 2 ) atmospheric environments at 50°C (12-15 M Cl − and pH~5) with different mechanical elastic and elastic/plastic loads were carried out over a period of 21 months. The corrosion rates for grade 2202 increased over time, showing selective dissolution with shallow corrosion sites, coalescing along the surface of the wire. Corrosion rates of grade 2205 decreased over time, showing both selective and pitting corrosion with more localised attack, growing preferentially in depth. The nucleation of stress corrosion cracking was observed in both wires.

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“…1,5,[7][8][9] Chromium nitrides can cause significant changes in microstructure performance 10,11 and hardness, 12 despite their small volume fractions and sizes (usually below 2 μm).…”

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Characterization of 475°C Embrittlement of Duplex Stainless Steel Microstructure via Scanning Kelvin Probe Force Microscopy and Magnetic Force Microscopy

Örnek

Walton

Hashimoto³

et al. 2017

J. Electrochem. Soc.

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Scanning Kelvin probe force microscopy (SKPFM) measured local Volta potentials in microstructure of 22Cr-5Ni duplex stainless steel have been correlated to microstructure development with aging treatments at 475 • C. Magnetic force microscopy (MFM) was employed to differentiate crystallographic phases to provide complementary information. The absolute Volta potentials of both ferrite and austenite increased after 5 hours of aging, indicating electrochemical ennoblement of the entire microstructure. Longer aging resulted in a gradual decrease of measured Volta potentials in both phases. The microstructure showed after 255 hours aging up to 2.5-times larger potential differences than in the as-received condition, indicating impaired electrochemical nobility. In the as-received microstructure, the ferrite phase was less noble than the austenite, whereas after 5 hours aging both phases had similar, balanced Volta potentials which indicated a balanced nobility of ferrite and austenite. Longer aging treatment caused severe loss of nobility for the entire microstructure, with ferrite showing larger changes in Volta potential than the austenite. Spinodal microstructure decomposition and associated phase reactions of the ferrite, with elemental redistribution in the austenite, are the reason for the observed changes in microstructure nobility. Duplex Stainless Steels (DSSs) have been used for structural and functional applications in a broad range of industry sectors.1 Their two-phase microstructure typically consists of a balanced fraction of ferrite (δ) and austenite (γ) resulting in beneficial properties, such as high strength and toughness, with outstanding corrosion and stress corrosion cracking resistance. However, when exposed to higher temperature regimes DSSs suffer from microstructure changes due to phase transformations arising from strong interactions of alloying elements.2-4 These microstructure changes can be accompanied by the occurrence of embrittlement and loss in corrosion resistance, which restricts their use in high-temperature applications.When the material is exposed to temperatures between 600 • C and 1000• C, the microstructure can decompose into several secondary phases.5-7 Ferrite can undergo eutectoid transformations into several phases, including σ-phase with secondary austenite (γ 2 ), χ-phase, carbides (mainly M 23 C 6 ), nitrides (CrN and Cr 2 N), or carbonitrides. 1,5,[7][8][9] Chromium nitrides can cause significant changes in microstructure performance 10,11 and hardness, 12 despite their small volume fractions and sizes (usually below 2 μm).12,13 Precipitation is typically accompanied by significant reductions in localized corrosion resistance, and is mainly attributed to the formation of element-depleted regions adjacent to secondary phases. [5][6][7] Exposure to lower temperatures between 250• C to 550• C, often referred to "475• C embrittlement", also results in variations of mechanical and electrochemical properties.14-28 This has been attributed to phase separation mechanisms, prim...

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Correlative EBSD and SKPFM characterisation of microstructure development to assist determination of corrosion propensity in grade 2205 duplex stainless steel

Cited by 65 publications

References 67 publications

Volta Potential Evolution of Intermetallics in Aluminum Alloy Microstructure Under Thin Aqueous Adlayers: A combined DFT and Experimental Study

Volta Potential Evolution of Intermetallics in Aluminum Alloy Microstructure Under Thin Aqueous Adlayers: A combined DFT and Experimental Study

Time-dependent in situ measurement of atmospheric corrosion rates of duplex stainless steel wires

Characterization of 475°C Embrittlement of Duplex Stainless Steel Microstructure via Scanning Kelvin Probe Force Microscopy and Magnetic Force Microscopy

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