Nanostructure evolution and mechanical property changes during aging of a super duplex stainless steel at 300 °C

Pettersson, Niklas; Wessman, Sten; Thuvander, Mattias; Hedström, Peter; Odqvist, Joakim; Pettersson, Rachel; Hertzman, Staffan

doi:10.1016/j.msea.2015.09.009

Cited by 52 publications

(45 citation statements)

References 26 publications

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“…Elongated dimples typically indicate shear deformation, clearly evidencing ductile fracture behavior. These observations are in good agreement with Pettersson et al [38] and de Lacerda et al [39] who also reported ductile fracture surface for DSS in the as-received condition (solution annealed). Easy slip activity from ferrite and austenite, and vice versa, is reported for as-received duplex microstructure.…”

Section: Fracture Surface Analysissupporting

confidence: 91%

748 K (475 °C) Embrittlement of Duplex Stainless Steel: Effect on Microstructure and Fracture Behavior

Örnek

Burke

Hashimoto

et al. 2017

Metall Mater Trans A

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22Cr-5Ni duplex stainless steel (DSS) was aged at 748 K (475°C) and the microstructure development correlated to changes in mechanical properties and fracture behavior. Tensile testing of aged microstructures confirmed the occurrence of 748 K (475°C) embrittlement, which was accompanied by an increase of strength and hardness and loss of toughness. Aging caused spinodal decomposition of the ferrite phase, consisting of Cr-enriched a¢¢ and Fe-rich a¢ and the formation of a large number of R-phase precipitates, with sizes between 50 and 400 nm. Fracture surface analyses revealed a gradual change of the fracture mode from ductile to brittle delamination fracture, associated with slip incompatibility between ferrite and austenite. Ferrite became highly brittle after 255 hours of aging, mainly due to the presence of precipitates, while austenite was ductile and accommodated most plastic strain. The fracture mechanism as a function of 748 K (475°C) embrittlement is discussed in light of microstructure development.

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Section: Fracture Surface Analysissupporting

confidence: 91%

748 K (475 °C) Embrittlement of Duplex Stainless Steel: Effect on Microstructure and Fracture Behavior

Örnek

Burke

Hashimoto

et al. 2017

Metall Mater Trans A

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“…APT is today considered to be the only technique capable of 3D atomic level chemical mapping, but the investigated volumes are small, typically in the order of 50 9 50 9 250 nm 3 . The detection efficiency of a typical instrument today, the local electrode atom probe (LEAP), is below about 65 pct and thus almost half of the atoms are lost in the analysis.…”

Section: Experimental Methods For Characterization Of Phase Separmentioning

confidence: 99%

“…Samples for SANS measurements were cut into plates with the approximate dimensions 5 9 5 9 1.5 mm 3 , and the oxide layer was removed by grinding and polishing. SANS data were then recorded on the LOQ diffractometer at the ISIS pulsed neutron source, Oxfordshire, UK.…”

Section: B Sans Measurementsmentioning

confidence: 99%

“…The embrittlement phenomenon is known as ''475°C embrittlement'' and, for instance, it limits the application temperature of duplex stainless steels to about 523 K (250°C). [3] Due to the high technical relevance and its suitability as a model material for phase separation studies, binary Fe-Cr alloys have been extensively investigated. Theoretical tools such as phase-field modeling [4][5][6] and kinetic Monte Carlo [7][8][9][10] are frequently adopted to simulate the nanostructure evolution, and experimental tools such as Mo¨ssbauer spectroscopy (MS), [11][12][13][14] transmission electron microscopy (TEM), [4,5,[15][16][17] small-angle neutron scattering (SANS), [18][19][20][21][22][23][24][25] atom probe field ion microscopy (APFIM), [7][8][9]26,27] and later atom probe tomography (APT) [10,[28][29][30][31][32][33][34] have been applied.…”

Section: Introductionmentioning

confidence: 99%

“…Most of the studies in the literature focus on the rather late stages of phase decomposition, when the embrittlement is already severe, and today it is still considered a major challenge to quantitatively characterize the nanostructure in technically relevant cases, when the length-scale is in the order of a few atomic distances and the concentration variations between a and a¢ are only a few atomic percent. [3,27,35] The purpose of the present work is to compare and discuss currently available experimental methodologies for structural characterization of phase separation in Fe-Cr alloys. In prior work, some of the present authors have presented APT and TEM studies of phase separation in binary Fe-Cr alloys exposed to aging at 773 K (500°C).…”

Section: Introductionmentioning

confidence: 99%

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Structural Characterization of Phase Separation in Fe-Cr: A Current Comparison of Experimental Methods

Odqvist

Colliander

et al. 2016

Metall Mater Trans A

Self Cite

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Self-assembly due to phase separation within a miscibility gap is important in numerous material systems and applications. A system of particular interest is the binary alloy system Fe-Cr, since it is both a suitable model material and the base system for the stainless steel alloy category, suffering from low-temperature embrittlement due to phase separation. Structural characterization of the minute nano-scale concentration fluctuations during early phase separation has for a long time been considered a major challenge within material characterization. However, recent developments present new opportunities in this field. Here, we present an overview of the current capabilities and limitations of different techniques. A set of Fe-Cr alloys were investigated using small-angle neutron scattering (SANS), atom probe tomography, and analytical transmission electron microscopy. The complementarity of the characterization techniques is clear, and combinatorial studies can provide complete quantitative structure information during phase separation in Fe-Cr alloys. Furthermore, we argue that SANS provides a unique in-situ access to the nanostructure, and that direct comparisons between SANS and phase-field modeling, solving the non-linear Cahn Hilliard equation with proper physical input, should be pursued.

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Short‐term spinodal decomposition – its effects on corrosion behaviour of a duplex stainless steel and feasibility as a strengthening treatment

Kuan

Dong

et al. 2016

Materials & Corrosion

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The present paper looks into the effects of spinodal decomposition (SD) on the corrosion resistance and cavitation erosion behaviour of the duplex stainless steel (DSS) 7MoPLUS. SD takes place at 500 8C in the ferrite phase at the early stage of thermal ageing, with an attendant hardness increase. Nevertheless, thermal ageing at this temperature for up to 2 days nearly does not reduce pitting potential (in 3.5% NaCl). Surface integrity, however, is degraded by the appearance of noticeable pits after just a few hours of exposure to this temperature. Ageing for 1 week at 500 8C does not seem to alter the corrosion morphology of the ferrite phase in 1 M HCl. On the other hand, SD does bring about changes to the nature of passive film, as demonstrated by open-circuit potential measurements in 3.5% NaCl. The cavitation erosion (CE) resistance of 7MoPLUS is slightly enhanced by short-term SD treatment (for 5 h), as propagation of CE damage emanating from deformation twins in the ferrite phase is made less efficient. It is suggested that short-term SD treatment is a feasible strengthening method for DSSs.

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Nanostructure evolution and mechanical property changes during aging of a super duplex stainless steel at 300 °C

Cited by 52 publications

References 26 publications

748 K (475 °C) Embrittlement of Duplex Stainless Steel: Effect on Microstructure and Fracture Behavior

748 K (475 °C) Embrittlement of Duplex Stainless Steel: Effect on Microstructure and Fracture Behavior

Structural Characterization of Phase Separation in Fe-Cr: A Current Comparison of Experimental Methods

Short‐term spinodal decomposition – its effects on corrosion behaviour of a duplex stainless steel and feasibility as a strengthening treatment

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