Low-field magnetic analysis for sigma phase embrittlement monitoring in thermally aged 22Cr duplex stainless steel

Silva, David D.S.; Raimundo, Rafael A.; Torquato, Ramon Alves; Faria, Geraldo Lúcio de; Morales, Marco A.; Simões, Thiago A.; Gomes, Rodinei Medeiros

doi:10.1016/j.jmmm.2020.167072

Cited by 10 publications

(4 citation statements)

References 41 publications

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Section: Structural Morphological and Mechanical Characterizationsupporting

confidence: 94%

“…The precipitation of the σ phase led to the formation of γ 2 in a process defined as eutectoid decomposition (α → σ + γ 2 ); as seen in Figure2c. These results are in agreement with previously studies[29,30].These optical microscopies (OM) show that the secondary phases grew at the expense of the α-Fe phase. However, these results do not provide a good contrast for distinguishing between the various secondary phases, mainly the σ, χ, and γ 2 phases.…”

supporting

confidence: 93%

“…The effect of the sigma phase on mechanical properties deserves to be studied, since a small fraction of this phase affects ductility and toughness [27,28]. Recently, Silva et al [29,30] investigated the use of an electromechanical impedance (EMI) technique and low-field magnetic analysis (LFMA) in the monitoring of sigma phase embrittlement in DSS, in order to assess modifications in the microstructure of thermally degraded 2205 DSS at 800 • C for different time intervals. The authors confirmed that small σ contents (about 6%) promoted a considerable decrease of approximately 63% of toughness in DSS.…”

Section: Introductionmentioning

confidence: 99%

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The Effect of Microstructural Changes on Mechanical and Electrochemical Corrosion Properties of Duplex Stainless Steel Aged for Short Periods

et al. 2020

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This work reports the effects of crystallographic changes due to the secondary phases, in particular sigma (σ), on the mechanical properties and electrochemical behavior of thermally aged duplex stainless steel (DSS). Structural, morphological, mechanical, and electrochemical characterizations were performed. Sigma phase content increased with increasing aging treatment time. It had a lamellar-like shape, as observed by electron backscatter diffractometry (EBSD). Its presence directly damaged mechanical properties. The corrosion assessment included electrochemical impedance spectroscopy (EIS) in 1 M NaCl solution at temperatures of 25, 40, and 65 °C. EIS results demonstrate that an increase in the σ phase content decreased the corrosion resistance (21.1–0.8, 3.5–0.3, and 3.1–0.2 kΩ cm2 at 25, 40, and 60 °C, respectively).

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Section: Structural Morphological and Mechanical Characterizationsupporting

confidence: 94%

supporting

confidence: 93%

Section: Introductionmentioning

confidence: 99%

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The Effect of Microstructural Changes on Mechanical and Electrochemical Corrosion Properties of Duplex Stainless Steel Aged for Short Periods

et al. 2020

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“…The latter differs from untransformed austenite, since it contains less molybdenum and chromium, thus causing serious deficiencies in the properties of the steel. The precipitation of 1% of σ phase can decrease 50% the energy absorption in the impact test 19,24 . Since the sigma intermetallic phase is composed of several types of atoms, e.g., Cr, Mo and Fe, a quantitative solution of its precipitation-dissolution mechanism becomes complex.…”

Section: Sample Conditionsmentioning

confidence: 99%

Dilatometric Cycles in the Study of Precipitation of Intermetallic Phases in Duplex Stainless Steels

et al. 2020

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Duplex stainless steels (DSS) are used in offshore platforms due to their good properties resulting from the combination of two phases, namely austenite and ferrite. Secondary intermetallic phases, such as alpha prime (α´) and sigma (σ), which are harmful, can be formed at temperatures above 400 °C, or by a casting process. This study investigates the formation of sigma phase by thermal cycles running in a dilatometer (800 °C, 850 °C, 900 °C and 1,000 °C) for 1h, and at 850 °C for 3h and 7h. The optical microscopy of the DSS microstructure subjected to 800, 850 and 900 °C for one hour revealed a small fraction of σ phase with nucleation in the contour of ferrite/austenite phases, and tests by ferritoscope indicated a decrease (~4%) in a magnetic fraction (ferrite). However, samples subjected to dilatometric cycles at 850 °C for 3 hours showed an 18% decrease in the magnetic phase and quantitative metallography revealed a 33% fraction of σ phase precipitated in the ferrite phase. Tests conducted at 850 ºC for 7 hours indicated a high fraction of σ phase precipitated (approximately 50%), starting in the grain boundary, austenite/ferrite, and advancing in ferrite grain.

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Non-destructive techniques for the detection of sigma phase in duplex stainless steel: A comprehensive review

Biezma

Martin

Linhardt

et al. 2021

Engineering Failure Analysis

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Low-field magnetic analysis for sigma phase embrittlement monitoring in thermally aged 22Cr duplex stainless steel

Cited by 10 publications

References 41 publications

The Effect of Microstructural Changes on Mechanical and Electrochemical Corrosion Properties of Duplex Stainless Steel Aged for Short Periods

The Effect of Microstructural Changes on Mechanical and Electrochemical Corrosion Properties of Duplex Stainless Steel Aged for Short Periods

Dilatometric Cycles in the Study of Precipitation of Intermetallic Phases in Duplex Stainless Steels

Non-destructive techniques for the detection of sigma phase in duplex stainless steel: A comprehensive review

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