G-phase precipitation in austenitic stainless steel deformed by high pressure torsion

Shuro, Innocent; Kuo, Ho Hung; Sasaki, Taisuke; Hono, K.; Todaka, Yoshikazu; Umemoto, Minoru

doi:10.1016/j.msea.2012.05.030

Cited by 49 publications

(24 citation statements)

References 15 publications

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“…The crystal structure of the G phase detected in the current specimen is consistent with previous observations, although the lattice parameter is slightly smaller (a = 1.115-1.120 nm [12]). However, the phase appears to have a significantly lower silicon content compared to other studies [12,14,19,23]. It is possible that this difference accounts for the smaller lattice parameter of the crystal lattice compared to previous studies.…”

Section: G Phasecontrasting

confidence: 53%

“…The composition corresponds to (Fe,Ni,Mo) 16 (Cr) 6 Si 2 . Previous workers have reported various compositions of the G phase in a range of austenitic stainless steels: a typical example for the compositions is (Ni, Fe, Mo, Cr) 16 (Nb, Mn, Cr, Ti) 6 Si 6 or 7 [12,14,19,23]. The crystal structure of the G phase detected in the current specimen is consistent with previous observations, although the lattice parameter is slightly smaller (a = 1.115-1.120 nm [12]).…”

Section: G Phasementioning

confidence: 99%

“…Precipitates commonly found include both a-and d-ferrite, various carbides [8], and complex phases such as sigma phase, R phase and G phase. One of the less encountered precipitates is G phase, a silicon containing FCC intermetallic phase (a = 1.115-1.120 nm [12]) with a nominal composition observed in austenitic stainless steels [12][13][14][15][16][17][18][19][20] of (Ni/Fe/Cr) 16 (Nb/ Ti) 6 Si 6 [12]. By comparison, in duplex stainless steels [12,21,22] the composition is (Fe/Ni) 16 (Mn/Cr) 6 Si 7 [19].…”

Section: Introductionmentioning

confidence: 99%

“…By comparison, in duplex stainless steels [12,21,22] the composition is (Fe/Ni) 16 (Mn/Cr) 6 Si 7 [19]. Other studies have found that substitution of Mo for Ni is possible [14,23]. G phase precipitates form within the ferrite regions of duplex [21,22] and nominally austenitic stainless steels (e.g.…”

Section: Introductionmentioning

confidence: 99%

“…G phase precipitates form within the ferrite regions of duplex [21,22] and nominally austenitic stainless steels (e.g. Type 300 series austenitic steels) [13,15,16,19] during ageing within the temperature range of 250-500°C [12,14,22]. This phase typically nucleates and grows at austenite grain boundaries [21,24], and/or at austenite-a-ferrite phase boundaries but in the latter case it has a cube-on-cube orientation relationship with the ferrite [19,21].…”

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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Section: G Phasecontrasting

confidence: 53%

Section: G Phasementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

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

2018

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Strength‐Ductility Synergy in 304 Austenitic Steel with a Phase‐Reversion‐Induced Heterogeneous Lamellar Microstructure

Zeng,

Wen,

Jiang

et al. 2024

Adv Eng Mater

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A thermo‐mechanical processing route involving severe cold‐rolling deformation of austenite to generate strain‐induced martensite, followed by short‐time annealing when martensite reverts to austenite, was used to introduce the heterogeneous lamellar structures (HLS) into 304 stainless steel (304ss). Firstly, a nanolamellar structure consisting of mostly martensite with retained austenite grains was formed in the severe cold‐rolled 304ss, which results in an ultra‐high strength of ∽1.9 GPa but poor ductility. After short‐time annealing, a HLS, comprised of soft recrystallized austenite lamellae with micro/sub‐micron grains embedded inside a hard matrix of reversed ultrafine/nano austenite grains containing high‐density dislocations, was introduced into the 304ss through phase reversion and partial recrystallization. The resultant HSLed 304ss exhibits a high yield strength in excess of 1.2 GPa with a large uniform elongation of ∽28%. Strong hetero‐deformation induced (HDI) hardening associated with the joint activation of twin‐induced plasticity (TWIP) and transformation‐induced plasticity (TRIP) effect are responsible for the excellent strength‐ductility combination. The thermo‐mechanical processing route used here can be easily scaled up for industrial production, and could be generalized to other materials.This article is protected by copyright. All rights reserved.

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Effect of spinodal decomposition on the pitting corrosion resistance of Z3CN20.09M duplex stainless steel

Chen

Dai

et al. 2017

Materials & Corrosion

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The microstructural characterization and pitting corrosion behavior of Z3CN20.09M duplex stainless steel were investigated by TEM, potentiodynamic polarization, and electrochemical impedance spectroscopy after thermal aging at 475 °C for 0, 500, 1000, 2000, and 3000 h. The results showed that the ferrite in the steel decomposes into coherent Cr‐rich, Fe‐rich, and G phases. No any precipitates were found in the austenite during the thermal aging process. It is revealed that the pitting resistance of this steel has a negative relationship with increasing aging time and the priority nucleation position changes before and after the thermal aging process. The composition fluctuation region adjacent to the G phase and the Cr‐depleted region around the Cr‐rich phase are preferential to form pits. Therefore the G phase precipitation and the formation of Cr‐depleted region are harmful to the pitting resistance of the steel.

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G-phase precipitation in austenitic stainless steel deformed by high pressure torsion

Cited by 49 publications

References 15 publications

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

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

Strength‐Ductility Synergy in 304 Austenitic Steel with a Phase‐Reversion‐Induced Heterogeneous Lamellar Microstructure

Effect of spinodal decomposition on the pitting corrosion resistance of Z3CN20.09M duplex stainless steel

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