Influence of the shielding gas composition on the passive film and erosion corrosion of tube-to-tube sheet welds of hyper duplex stainless steel

Kim, Hye Jin; Jeon, Soon-Hyeok; Kim, Soontae; Park, Yong Soo

doi:10.1016/j.corsci.2014.11.014

Cited by 40 publications

(11 citation statements)

References 38 publications

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“…[6,7,8]. The precipitation of deleterious secondary phases, which are mostly enriched in Cr, Mo, and/or N, decrease the local corrosion resistance around the precipitates and often result in local corrosion attacks [1,9,10]. In addition to the loss of corrosion resistance, the precipitation of secondary phases significantly reduces the mechanical properties of SDSS [6].…”

Section: Introductionmentioning

confidence: 99%

Effect of Sigma Phase Morphology on the Degradation of Properties in a Super Duplex Stainless Steel

et al. 2018

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Sigma phase is commonly considered to be the most deleterious secondary phase precipitating in duplex stainless steels, as it results in an extreme reduction of corrosion resistance and toughness. Previous studies have mainly focused on the kinetics of sigma phase precipitation and influences on properties and only a few works have studied the morphology of sigma phase and its influences on material properties. Therefore, the influence of sigma phase morphology on the degradation of corrosion resistance and mechanical properties of 2507 super duplex stainless steel (SDSS) was studied after 10 h of arc heat treatment using optical and scanning electron microscopy, electron backscattered diffraction analysis, corrosion testing, and thermodynamic calculations. A stationary arc was applied on the 2507 SDSS disc mounted on a water-cooled chamber, producing a steady-state temperature gradient covering the entire temperature range from room temperature to the melting point. Sigma phase was the major intermetallic precipitating between 630 °C and 1010 °C and its morphology changed from blocky to fine coral-shaped with decreasing aging temperature. At the same time, the average thickness of the precipitates decreased from 2.9 µm to 0.5 µm. The chemical composition of sigma was similar to that predicted by thermodynamic calculations when formed at 800–900 °C, but deviated at higher and lower temperatures. The formation of blocky sigma phase introduced local strain in the bulk of the primary austenite grains. However, the local strain was most pronounced in the secondary austenite grains next to the coral-shaped sigma phase precipitating at lower temperatures. Microstructures with blocky and coral-shaped sigma phase particles were prone to develop microscale cracks and local corrosion, respectively. Local corrosion occurred primarily in ferrite and in secondary austenite, which was predicted by thermodynamic calculations to have a low pitting resistance equivalent. To conclude, the influence of sigma phase morphology on the degradation of properties was summarized in two diagrams as functions of the level of static load and the severity of the corrosive environment.

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Section: Introductionmentioning

confidence: 99%

Effect of Sigma Phase Morphology on the Degradation of Properties in a Super Duplex Stainless Steel

et al. 2018

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“…HDSS contains high levels of Cr, Mo and N 11 , resulting in its excellent corrosion resistance and a high value (45–50) of pitting resistance equivalent number (PREN), which is calculated from wt.% Cr + 3.3 (wt.% Mo + 0.5 wt.% W) + 16 wt.% N 12 . Its excellent corrosion resistance properties rely on a well-balanced composition with approximately 50% ferrite (α) and 50% austenite (γ) phases, that offer HDSS improved mechanical properties and higher chloride corrosion resistance compared with conventional DSS 13 . The improved corrosion resistance extends the use of HDSS in more aggressive chloride environments, such as marine environments.…”

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confidence: 99%

Microbiologically Influenced Corrosion of 2707 Hyper-Duplex Stainless Steel by Marine Pseudomonas aeruginosa Biofilm

Zhou

Zhang

et al. 2016

Sci Rep

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Microbiologically Influenced Corrosion (MIC) is a serious problem in many industries because it causes huge economic losses. Due to its excellent resistance to chemical corrosion, 2707 hyper duplex stainless steel (2707 HDSS) has been used in the marine environment. However, its resistance to MIC was not experimentally proven. In this study, the MIC behavior of 2707 HDSS caused by the marine aerobe Pseudomonas aeruginosa was investigated. Electrochemical analyses demonstrated a positive shift in the corrosion potential and an increase in the corrosion current density in the presence of the P. aeruginosa biofilm in the 2216E medium. X-ray photoelectron spectroscopy (XPS) analysis results showed a decrease in Cr content on the coupon surface beneath the biofilm. The pit imaging analysis showed that the P. aeruginosa biofilm caused a largest pit depth of 0.69 μm in 14 days of incubation. Although this was quite small, it indicated that 2707 HDSS was not completely immune to MIC by the P. aeruginosa biofilm.

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“…Kim et al [12] performed GTAW welding tests with Ar shielding gas in a hyper-duplex steel getting equal volume fractions of ferrite and austenite for welding with a filler metal, however the joint without a filler metal, presented 80% of ferrite, thus exhibiting a low corrosion resistance. In a more recent study [13], the authors have investigated the possibility to improve the weld joint without filler metal by the addition of 2% N2 in the shielding gas. With the addition of N2, Kim et al [13] reached a welded joint with 60% of ferrite, still a higher value than the ideal volume fraction of 50% ferrite.…”

Section: Introductionmentioning

confidence: 99%

Nitrogen Addition to the Shielding Gas for Welding Hyper-duplex Stainless Steel

et al. 2020

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In the present work we have studied the effects of nitrogen addition on the equilibrium of the volume fraction ratio austenite/ferrite and on the structural properties of weldments produced by gas tungsten arc welding (GTAW). The welded joints in tubes UNS S32707 of hyper-duplex steel were produced using argon and nitrogen gas welding, with nitrogen added in ratios of 1.5, 2.5, 3.5, 4.5, and 5.5%. Microstructural characterization of this material under the different processing condition was conducted by means of optical microscopy, scanning electron microscopy, local chemical analysis by X-ray energy dispersive spectroscopy, electron backscatter diffraction Vickers microhardness test, and digital image processing. All welding conditions resulted in welded joints with equiaxial grains microstructure containing austenite both at the boundaries and in the ferrite matrix. Microhardness measurements did not show significant variation in relation to the base metal. The use of welding gases with higher percentages of nitrogen resulted in increases in the austenite volume fraction in the order of 39 to 57% when considering the nitrogen content ranging from 1.5 to 5.5%.

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Influence of the shielding gas composition on the passive film and erosion corrosion of tube-to-tube sheet welds of hyper duplex stainless steel

Cited by 40 publications

References 38 publications

Effect of Sigma Phase Morphology on the Degradation of Properties in a Super Duplex Stainless Steel

Effect of Sigma Phase Morphology on the Degradation of Properties in a Super Duplex Stainless Steel

Microbiologically Influenced Corrosion of 2707 Hyper-Duplex Stainless Steel by Marine Pseudomonas aeruginosa Biofilm

Nitrogen Addition to the Shielding Gas for Welding Hyper-duplex Stainless Steel

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