Chi-phase precipitation in a duplex stainless steel

Escriba, D.M.; Materna-Morris, E.; Plaut, Ronald Lesley; Padilha, Angelo Fernando

doi:10.1016/j.matchar.2009.04.013

Cited by 187 publications

(165 citation statements)

References 10 publications

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“…Furthermore, the χ phase is enriched in Cr and Mo in comparison with the matrix [21][22][23], which explains why it is visible as a bright phase in BSE contrast. The formation of χ phase results from the high supersaturation of first crystals, as a consequence of non-equilibrium solidification with a relatively high cooling rate.…”

Section: Microstructurementioning

confidence: 99%

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Experimental and Thermodynamic Study of Selected in-Situ Composites from the Fe-Cr-Ni-Mo-C System

Wieczerzak

Bała

Dziurka

et al. 2016

Archives of Metallurgy and Materials

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The aim of the study was to synthesize and characterize the selected in-situ composites from the Fe-Cr-Ni-Mo-C system, additionally strengthened by intermetallic compounds. The project of the alloys was supported by thermodynamic simulations using Calculation of Phase Diagram approach via Thermo-Calc. Selected alloys were synthesized in an arc furnace in a high purity argon atmosphere using a suction casting unit. The studies involved a range of experimental techniques to characterize the alloys in the as-cast state, including optical emission spectrometry, light microscopy, scanning electron microscopy, electron microprobe analysis, X-ray diffraction and microhardness tests. These experimental studies were compared with the Thermo-Calc data and high resolution dilatometry. The results of investigations presented in this paper showed that there is a possibility to introduce intermetallic compounds, such as χ and σ, through modification of the chemical composition of the alloy with respect to Ni eq and Cr eq . It was found that the place of intermetallic compounds precipitation strongly depends on matrix nature. Results presented in this paper may be successfully used to build a systematic knowledge about the group of alloys with a high volume fraction of complex carbides, and high physicochemical properties, additionally strengthened by intermetallic compounds.

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Section: Microstructurementioning

confidence: 99%

“…3b). This sequence results in the formation of δ/γ interfaces, which are preferential sites for χ phase nucleation [21,22]. Michalska and Sozańska [22] show that in 2205 duplex steel χ phase precipitates at the ferrite-austenite interface and into the adjacent ferrite matrix.…”

Section: Microstructurementioning

confidence: 99%

Experimental and Thermodynamic Study of Selected in-Situ Composites from the Fe-Cr-Ni-Mo-C System

Wieczerzak

Bała

Dziurka

et al. 2016

Archives of Metallurgy and Materials

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show abstract

“…Chi phase is a BCC intermetallic phase (a = 0.881-0.895 nm [12]) the precipitation of which only occurs in Mo-or Ti-containing stainless steels [12,26]. Depending on the relative concentrations of Mo and Ti, the composition of the chi phase ranges from (Fe/Ni) 36 [12,24,[26][27][28], and there is potential for substitution of other elements [28].…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…Depending on the relative concentrations of Mo and Ti, the composition of the chi phase ranges from (Fe/Ni) 36 [12,24,[26][27][28], and there is potential for substitution of other elements [28]. The composition of chi phase is frequently likened to that of sigma phase, with the principle differences being the solubility of carbon [12,26] and higher concentrations of molybdenum [26,29,30]. Chi phase has been observed to nucleate and grow preferentially into the ferrite regions of dual phase (austenite-ferrite) steels [26,[29][30][31][32], at grain boundaries of d-ferrite [26,32], at austenite-dferrite grain edges and nodes [32] and austenite-dferrite phase boundaries [29,30,32].…”

Section: Introductionmentioning

confidence: 99%

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Precipitation within localised chromium-enriched regions in a Type 316H austenitic stainless steel

2018

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A Type 316H austenitic stainless steel component containing Cr and impurity element-rich localised regions arising from component fabrication was aged for a prolonged period during service at a temperature of approximately 550°C. These regions make up approximately 5% of the total volume of the microstructure. Previous work has shown that these regions contain ferrite and carbide precipitates and a finer austenite grain size than the adjacent matrix. The present study has used high-resolution transmission electron microscopy combined with compositional microanalysis to show that these regions have a highly complex microstructure containing G phase, chi phase and intragranular c 0 precipitates within the austenite grains. There is phosphorus migration to the chi austenite phase boundary, and the basis for this equilibrium impurity segregation is discussed. A Cr-depleted region was observed surrounding the chi phase precipitates, and the impact of this on the other precipitates is considered. The diversity of precipitates in these Cr-rich regions means that they behave significantly differently to the bulk material under long-term creep conditions leading to preferred nucleation and growth of creep cavities and the formation of localised creep cracks during service.

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Interactions of Desulfovibrio desulfuricans biofilm with 2205 duplex stainless steel – the role of microstructure

Michalska

Chmiela

Simka

2018

Materials & Corrosion

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The paper presents the results on sulfate‐reducing bacteria (SRB) induced corrosion of 2205 duplex stainless steel (DSS) in as‐received and thermally aged conditions. Biofilm formation and damage process stimulated by DSM642 strain were analyzed with reference to its metabolic activity and to the surface characterization of structure and configuration of the biofilm. Electrochemical techniques were applied to monitor bacterial attachment to the steel surface and to determine the effect of bacteria on the passivity and corrosion resistance of 2205 DSS. Results demonstrated that MIC behavior was strongly affected by the microstructure and phase composition of the steel. Enhanced biofilm interactions were mainly limited to the austenitic phase, as well as primary (γ) and intergranular (γ2) austenite was found to be more prone to bacterial attack. Thermal aging of 2205 DSS led to the enhanced bacterial attack. Thermally aged samples were characterized by quicker and more intensive biofouling. Pitting and crevice‐type attacks were predominant on the thermally aged samples. It has been found that the presence of DSM642 biofilm changed the corrosion mechanism of 2205 DSS in 3.5% NaCl and the SRB‐induced selective attack was evident even for the material in phase‐balanced conditions.

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Chi-phase precipitation in a duplex stainless steel

Cited by 187 publications

References 10 publications

Experimental and Thermodynamic Study of Selected in-Situ Composites from the Fe-Cr-Ni-Mo-C System

Experimental and Thermodynamic Study of Selected in-Situ Composites from the Fe-Cr-Ni-Mo-C System

Precipitation within localised chromium-enriched regions in a Type 316H austenitic stainless steel

Interactions of Desulfovibrio desulfuricans biofilm with 2205 duplex stainless steel – the role of microstructure

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