Development of duplex stainless steels compositions

Zhitenev, Andrey; Fedorov, A. S.; Kazakov, A. A.; Fomina, O. V.

doi:10.17580/cisisr.2019.02.04

Cited by 10 publications

(4 citation statements)

References 23 publications

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“…The chemical composition of steels is shown in Table 1. Steel 1 was produced at laboratory scale [2] the raw materials used were high-purity electrical steel, metallic chromium, metallic nickel, ferromanganese-95, and ferromolybdenum-60. Heating and melting of the raw materials for 30-35 minutes, after which alloying and deoxidizing components were added to the furnace.…”

Section: Methodsmentioning

confidence: 99%

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Features of Crevice Corrosion of Different Grades of Duplex Stainless Steels

Fedorov

Karasev

Kovalev

2023

KEM

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Duplex stainless steels (DSSs) are being increasingly employed in the oil and gas and chemical industries, which, despite their high alloying degree and high resistance to general corrosion, are subject to pitting and crevice corrosion. According to their resistance to pitting and crevice corrosion, steels are ranked according to the PREN. However, nowadays there are many grades of DSSs, in which the content of Cr, Mo and N varies in different quantities, therefore the selection of the grade must be carried out with great care, considering not only PREN, but also the production technology, operating conditions, and the geometry of products. The crevice corrosion behaviors of three grades of duplex stainless steels quenched from 1050, 1100 and 1200 °C were studied in FeCl3 solution at 50°C. It is shown that PREN allows to rank only different grades in terms of corrosion resistance. With a constant PREN value, but with different contents of ferrite and austenite in steel, completely different values of the corrosion rate can be obtained, therefore, PREN must be used with great care. It was found that in the studied steels, the optimal ferrite content, at which the lowest crevice corrosion rate is achieved, is at 65 vol.%.

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Section: Methodsmentioning

confidence: 99%

“…Recently, in the oil and gas and chemical industries are increasingly being used products made of duplex stainless steels (DSSs), in which austenite and ferrite are in equal proportions [1][2][3][4]. Due to this phase ratio, these steels have high corrosion resistance along with enhanced mechanical properties [5][6][7].…”

Section: Introductionmentioning

confidence: 99%

Features of Crevice Corrosion of Different Grades of Duplex Stainless Steels

Fedorov

Karasev

Kovalev

2023

KEM

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“…Therefore, to describe and predict the corrosion properties of specific grades of DSSs, it is advisable to explore other approaches. In earlier studies by the authors, an attempt was made to develop a methodology for selecting the chemical composition and processing technology, considering the prediction of the phase composition via thermodynamic modeling [14]. Critical points on the phase diagram were proposed, the positions of which relative to the temperatures of a particular treatment determine the final properties of the product:…”

Section: Introductionmentioning

confidence: 99%

Development of Thermodynamic Criteria for Determining the Composition of Duplex Stainless Steels with High Corrosion Resistance

Fedorov,

Karasev,

Kovalev

et al. 2024

Materials

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One of the most popular methods for ranking duplex stainless steels (DSSs) and predicting their corrosion properties is the calculation of the pitting resistance equivalent number (PREN). However, since DSSs are two-phase materials with a significant fraction of secondary phases and precipitates, the application of the PREN can be highly limited. This article attempted to use a new approach to describe the corrosion resistance of these steels. The corrosion resistance of two DSSs of the same class was investigated. Under identical solution heat treatments in the temperature range of 1050–1200 °C, the crevice corrosion resistance of one steel increased, while that of the other decreased. It was demonstrated that the amounts of austenite and ferrite changed similarly in these steels, and the different corrosion resistances were associated with the behaviors of secondary phases: niobium carbonitride and chromium nitride. SEM-EDS analysis was conducted to analyze the redistribution of elements between phases in both cases, showing good agreement with the thermodynamic modeling results. The PREN was calculated for each phase depending on the treatment temperature, and a method for calculating the effective PREN (PRENeff), accounting for phase balance and secondary phases, was proposed. It was shown that this indicator described corrosion properties better than the classical PREN calculated for the average steel composition. This study demonstrated how the calculation of critical temperatures (the temperature of equal amounts of ferrite and austenite, the temperature of the beginning of chromium nitride formation, and the temperature of the beginning of σ-phase formation) could describe the corrosion resistance of DSSs. Maximum possible deviations from these temperatures were defined, allowing the attainment of the required corrosion properties for the steels. Based on the conducted research, an approach for selecting new compositions of DSSs was proposed.

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“…Despite the very successful applications and experience of DSSs, the development of highly alloyed DSSs has been very active since there are still areas where the corrosion resistance of the current DSSs has been insufficient for a long service life or at higher temperatures. Based on this challenge, the flagship hyper DSS, UNS S33207 (marked as S33207 from herein), which has the highest corrosion resistance and strength among the existing modern DSSs has since been developed [6][7][8][9].…”

Section: Introductionmentioning

confidence: 99%

Effect of Cooling Rate on Crystallization Behavior during Solidification of Hyper Duplex Stainless Steel S33207: An In Situ Confocal Microscopy Study

Wang

2023

Crystals

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Hyper duplex stainless steel (HDSS) is a new alloy group of duplex stainless steels with the excellent corrosion resistance and mechanical properties among the existing modern stainless steels. Due to the incorporation of the high content of alloying elements, e.g., Cr, Ni, Mo, etc., the crystallization behavior of δ-ferrite from liquid is of vital importance to be controlled. In this work, the effect of the cooling rate (i.e., 4 °C/min and 150 °C/min) on the nucleation and growth behavior of δ-ferrite in S33207 during the solidification was investigated using a high-temperature confocal scanning laser microscope (HT-CLSM) in combination with electron microscopies and thermodynamic calculations. The obtained results showed that the solidification mode of S33207 steel was a ferrite–austenite type (FA mode). L→δ-ferrite transformation occurred at a certain degree of undercooling, and merging occurred during the growth of the δ-ferrite phase dendrites. Similar microstructure characteristics were observed after solidification under two different cooling rates. The variation in the area fraction of δ-ferrite with different temperatures and time intervals during the solidification of S33207 steels was calculated at different cooling rates. The post-microstructure as well as its composition evolution were also briefly investigated. This work shed light on the real-time insights for the crystallization behavior of hyper duplex stainless steels during their solidification process.

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Development of duplex stainless steels compositions

Cited by 10 publications

References 23 publications

Features of Crevice Corrosion of Different Grades of Duplex Stainless Steels

Features of Crevice Corrosion of Different Grades of Duplex Stainless Steels

Development of Thermodynamic Criteria for Determining the Composition of Duplex Stainless Steels with High Corrosion Resistance

Effect of Cooling Rate on Crystallization Behavior during Solidification of Hyper Duplex Stainless Steel S33207: An In Situ Confocal Microscopy Study

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