Double-loop electrochemical potentiokinetic reactivation behaviour of continuously cooled SUS329J4L duplex stainless steel

Wang, Rongguang; Imagawa, Masanobu; Honda, Masaharu; Mori, Takayuki; Fukuhara, Hideki

doi:10.1080/1478422x.2017.1372246

Cited by 15 publications

(14 citation statements)

References 27 publications

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“…In previous XRD analysis 16) , the amount of σ phase in samples with the same composition as used in this study that had been continuously cooled with τ = 3115 s (0.2 K/s vs. 1073 ~ 773 K) and 5500 s (0.1 K/s) was 5.9% and 13.4% respectively, but no σ phase was detected when τ was 1795 s (0.3 K/s) or smaller. On the other hand, the Charpy absorbed energy of the sub-size samples at room temperature continually decreased with the time constant from τ = 445 s (1.0 K/s) to 28000 s (0.02 K/s).…”

Section: Epr Polarization Curves Of Laboratory Samplesmentioning

confidence: 67%

“…The σ phase precipitates in duplex stainless steel during both isothermal aging between 973 ~ 1173 K 5)-8),11)- 14) and continuous cooling from 1338 K 15)- 17) . In our previous study, XRD analysis showed that the amount of σ phase in SUS329J4L steel cooled at 0.02 K/s from 1073 to 773 K was 22.9% 16) . During isothermal aging, carbides (M23C6) form at the γ/α boundary and then grow into the neighboring γ phase 11) .…”

Section: Introductionmentioning

confidence: 88%

“…Therefore, in this study, the modified DL-EPR test 16) by using solutions with various DO concentrations was applied to SUS329J4L duplex stainless steel cooled by convection and the reactivation behavior corresponding to the precipitated σ phase was observed. Next, the validity of the modified test was confirmed by applying it to several samples in on-site simulations and by comparing it with immersion corrosion rates and Charpy impact test results.…”

Section: )mentioning

confidence: 99%

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Influence of Dissolved Oxygen on DL-EPR Behavior of SUS329J4L Duplex Stainless Steel after Convection Cooling

Wang¹,

Imagawa

Honda

et al. 2021

J. Soc. Mat. Sci., Japan

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Sigma phase precipitates in duplex stainless steel during slow cooling, degrading the corrosion resistance and the notch toughness. The double loop electrochemical potentiokinetic reactivation (DL-EPR) method in a solution of 0.5 M H2SO4 + 0.01 M KSCN + 0.5 M NaCl is known to be good for detecting sigma phase. However, the influence of dissolved oxygen (DO) in solution had not been elucidated, and on-site application of DL-EPR had not been carried out. In this study, SUS329J4L stainless steel was continuously cooled at different time constants by convection using nitrogen, and its DL-EPR behavior was measured in solution with different DO concentrations. A cathodic current partially appeared at potentials nobler than the corrosion potential due to the reduction of oxygen. Elimination of DO suppressed the cathodic reaction, resulting in adequate sensitivity for detection of precipitated sigma phase. The detection sensitivity was almost the same as that for laboratory samples in 700 mL/cm 2 solution and simulated small structures exposed to 20 mL/cm 2 solution, and with almost the same high sensitivity as the immersion corrosion test.

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Section: Epr Polarization Curves Of Laboratory Samplesmentioning

confidence: 67%

Section: Introductionmentioning

confidence: 88%

Section: )mentioning

confidence: 99%

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Influence of Dissolved Oxygen on DL-EPR Behavior of SUS329J4L Duplex Stainless Steel after Convection Cooling

Wang¹,

Imagawa

Honda

et al. 2021

J. Soc. Mat. Sci., Japan

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“…7 shows the observed thickness of passive film formed in water on the sigma (σ) and gamma prime (γ′) phases in sensitized SUS439J4L duplex SS after continuously cooling at 0.02 K/s between 1073 and 773 K. The solution-treated SUS329J4L generally contains two phases, ferrite (α) and austenite (γ), before sensitization. During the continuous slow cooling, the α phase changes to fine σ phase with high Cr content and γ′ phase with low Cr content to induce prior corrosion around σ phase 43 . In Fig.…”

Section: Discussionmentioning

confidence: 99%

“…This was to serve as a thickness reference, as it is inert under all conditions to which it was exposed in this study. SUS329J4L duplex SS of chemical composition Fe-0.029C-0.43Si-0.73Mn-0.038P-0.005S-24.19Cr-5.68Ni-2.68Mo-0.14 N, and annealed by continuously cooling at 0.02 K/s between 1073 and 773 K, with ferrite (α), austenite (γ, γ′) and sigma (σ) phases 43 , was used after being polished and cleaned as above.…”

Section: Methodsmentioning

confidence: 99%

Using Atomic Force Microscopy to Measure Thickness of Passive Film on Stainless Steel Immersed in Aqueous Solution

Wang

Xia

et al. 2019

Sci Rep

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Employing atomic force microscopy (AFM) to measure passive film thickness on stainless steel (SS) in aqueous solution is proposed. SUS304 austenite and SUS329J4L duplex SS samples partly covered by gold were set in a minicell. To remove the original film, the SS surface but gold was etched using dilute sulfuric acid. After cleaning, open circuit potential (OCP), and distance from the sample surface to the top of the gold were measured. They were then immersed in either 1.0% NaCl; 5.0% NaCl; or aqueous solution with pH ranging from 1.0 to 10.0 and measured again. Differences between the first and subsequent measures of OCP suggested a passive film had formed in solution with pH ranging from 2.8 to 10.0. Similarly, differences among AFM measures revealed the observed film thickness increased with increase in pH and with decrease in chloride ions. Also, film thickness in water was greater than that in a vacuum. Comparison of AFM measurements of passive film on the austenite and sigma phases in sensitized SUS329J4L duplex SS revealed the film was thinner on the sigma phase containing more chromium. Taken together, these findings suggest the proposed method is applicable for measuring the thickness of passive films in aqueous solution.

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Manufacturing of 2507 super duplex stainless steel by laser powder-directed energy deposition: process optimization and microstructure analyses

Ballésio,

Le Hong,

Dhondt

et al. 2024

Int J Adv Manuf Technol

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This paper presents a thorough manufacturability study of superduplex 2507 stainless steel (SDSS) produced by the Laser Powder-Directed Energy Deposition (LP-DED) process. First, experimental observations on single-track surface morphology and geometrical characteristics are described. Then, dimensional and porosity analyses of thin walls and bulk samples are presented and discussed in order to identify the optimal process parameter combinations, from a process point of view, for further characterizations to determine general properties of LP-DED-printed samples. Finally, the results obtained on a wrought steel of the same grade are finally compared to those of the printed material in terms of microstructure, texture and ferrite/austenite ratio. A set of meticulously chosen process parameters with regard to the process and the machine (nozzle size, maximum power deliverable) gives the optimal results for the as-built LP-DED material in terms of porosity and microstructure quality but with smaller grains (irrespective of the phase studied) and a higher proportion of ferrite (about 75 %).

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Double-loop electrochemical potentiokinetic reactivation behaviour of continuously cooled SUS329J4L duplex stainless steel

Cited by 15 publications

References 27 publications

Influence of Dissolved Oxygen on DL-EPR Behavior of SUS329J4L Duplex Stainless Steel after Convection Cooling

Influence of Dissolved Oxygen on DL-EPR Behavior of SUS329J4L Duplex Stainless Steel after Convection Cooling

Using Atomic Force Microscopy to Measure Thickness of Passive Film on Stainless Steel Immersed in Aqueous Solution

Manufacturing of 2507 super duplex stainless steel by laser powder-directed energy deposition: process optimization and microstructure analyses

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