Precipitation of sigma phase in duplex stainless steel and recent development on its detection by electrochemical potentiokinetic reactivation:A review

Wang, Rongguang

doi:10.1016/j.corcom.2021.08.001

Cited by 45 publications

(14 citation statements)

References 100 publications

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“…Because UNS S32750 is a highly alloyed steel, it is prone to the formation of secondary phases, such as the σ phase, during heat treatment and the pitting corrosion resistance decreases mainly due to the σ phase precipitation [8][9][10][11] . According to the UNS S32750 time-temperature-precipitation (TTP) diagrams, the σ phase precipitates within a few minutes at approximately 1200 K 12 . Therefore, suppressing σ phase precipitation is difficult without rapid cooling.…”

Section: Introductionmentioning

confidence: 99%

Micro-electrochemical insights into pit initiation site on aged UNS S32750 super duplex stainless steel

et al. 2023

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An aging treatment of UNS S32750 super duplex stainless steel at 1173 K for 1.0 ks produced σ and secondary austenite (γ2) phases in the α and γ phase boundary regions. Small amount of Mn-Cr oxide and MnS complex inclusions were present in the steel. No pitting was observed during the potentiodynamic polarization of a small area (200 × 200 µm) without inclusions in 1 M MgCl2 at 348 K. Because the electrode area included α, γ, σ, and γ2 phases, these phases and their boundaries alone could not act as initiation sites for pitting. The electrode area size was gradually reduced from 3 × 3 mm to 1 × 1 mm, and pitting corrosion was observed to occur at the Mn-Cr oxide and MnS complex inclusions in a region that appeared to be the γ2 phase near the σ phase.

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Section: Introductionmentioning

confidence: 99%

Micro-electrochemical insights into pit initiation site on aged UNS S32750 super duplex stainless steel

et al. 2023

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“…It is well known that several kinds of second phases such as carbide, σ phase, and χ phase would be precipitated with the element addition of Cr, Ni, and Mo in austenitic stainless steel during aging or annealing [14][15][16][17][18]. The precipitating behavior and its effect on the mechanical properties and corrosion resistance have been widely investigated [18][19][20]. However, little attention [11] has been paid to the pinning effect of second phase precipitating on maintaining the ultrafine-grained microstructure in austenitic stainless steel to the knowledge of authors.…”

Section: Introductionmentioning

confidence: 99%

Maintaining microstructure ultra-refinement in the austenitic stainless steel by inducing χ phase precipitating through severe cold rolling and annealing

Guan

Guo

et al. 2022

Mater. Res. Express

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In the present study, an austenitic stainless steel (2Cr17Ni13Mo5) was processed by severe cold rolling (SCR) and subsequent annealing. The austenitic grain size was severely refined to ~100 nm after SCR due to the high strain deformation. The yield strength (YS) and ultimate tensile strength (UTS) of SCRed steel increased to 1510.5 MPa and 1660.4 MPa, respectively. Nevertheless, the ductility decreased significantly showing very low strain hardening ability. Full recrystallization was completed after annealing at 800 oC for 1h. However, the ultrafine-grained structure was maintained with the grain size of 780 nm, which is mainly attributed to the pinning effect of χ-phase precipitated at the grain boundary during the annealing. Consequently, good comprehensive mechanical properties with high strength (YS=977.6 MPa, UTS=1197.7 MPa) and good ductility (elongation=17%) were achieved after annealing. The high strength is mainly attributed to the ultrafine-grained structure maintaining, while the annihilation of dislocation contributes to the ductility improvement.

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“…A decrease in material performance occurs due to the deleterious phases, such as sigma and chi phases, sometimes resulting in equipment failure [8,9]. Deleterious phase precipitation can generate sensitisation, a nanometric Crdepleted area in grain boundaries [8,[10][11][12][13][14].…”

Section: Introductionmentioning

confidence: 99%

“…Sigma (σ) phase is one of the most studied deleterious phases that can be present on DSS and SDSS [12,13,[15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33]. Temperature Time Transformation (TTT) diagrams show that this phase is usually formed in the 800-950°C temperature range [34][35][36].…”

Section: Introductionmentioning

confidence: 99%

DL-EPR vs. LSV-KOH: from simple detection of deleterious phases to analysis of morphology and high accuracy on determination of sigma phase in UNS S32750 stainless steel

Sampaio

Furtado

Ignácio

et al. 2022

Corrosion Engineering, Science and Technology

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An optimised electrochemical technique, linear sweep voltammetry (LSV) in KOH solution (LSV-KOH) was confronted with the double loop electrochemical Potentiokinetic reactivation (DL-EPR) to verify which is the best technique to quantify deleterious phases (DP) in a UNS S32750 super duplex stainless steel. DL-EPR presented an error in determination of deleterious phases in the range of 6.9-100%. LSV-KOH show a better accuracy in quantification of deleterious phases volume fractions, the error range for LSV-KOH was 2.4-26.2%. When the morphology of sigma changes from lamellar to divorced, was observed modifications on LSV-KOH voltammograms. In specimens where lamellar morphology is present, the voltammograms show two peaks curve. Meanwhile, in specimens where occurred also divorced precipitation of sigma the voltammograms changes to a 3 peaks curve. This feature is due to the dissolution of sigma phase boundaries which has different compositions according to the form of sigma precipitation.

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Precipitation of sigma phase in duplex stainless steel and recent development on its detection by electrochemical potentiokinetic reactivation:A review

Cited by 45 publications

References 100 publications

Micro-electrochemical insights into pit initiation site on aged UNS S32750 super duplex stainless steel

Micro-electrochemical insights into pit initiation site on aged UNS S32750 super duplex stainless steel

Maintaining microstructure ultra-refinement in the austenitic stainless steel by inducing χ phase precipitating through severe cold rolling and annealing

DL-EPR vs. LSV-KOH: from simple detection of deleterious phases to analysis of morphology and high accuracy on determination of sigma phase in UNS S32750 stainless steel

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