Strain-induced phase transformation at the surface of an AISI-304 stainless steel irradiated to 4.4dpa and deformed to 0.8% strain

Gussev, Maxim N.; Field, Kevin G.; Busby, Jeremy T.

doi:10.1016/j.jnucmat.2013.11.041

Cited by 33 publications

(12 citation statements)

References 20 publications

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“…The irradiated specimens are part of a cooperative research program on irradiationassisted stress corrosion cracking (IASCC) [37,38]. In previous reports of this program [39][40][41][42][43][44][45][46][47], the alloy of interest is referred to as "Alloy A" or "Heat A" with AS13 referring to the 5.5 dpa specimen, AS18 to the 10.2 dpa specimen, and AS23 to the 47.1 dpa specimen, for reference. Samples were prepared for scanning transmission electron microscopy (STEM) by mechanically polishing 3 mm diameter discs punched from acquired parent material to a thickness less than ~100 µm followed by electropolishing at -12°C in a methanol:sulfuric (7:1) solution using a Struers Tenupol polishing unit.…”

Section: Experimental Procedures For Ris Quantificationmentioning

confidence: 99%

Defect sink characteristics of specific grain boundary types in 304 stainless steels under high dose neutron environments

et al. 2015

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Radiation induced segregation (RIS) is a well-studied phenomena which occurs in many structurally relevant nuclear materials including austenitic stainless steels. RIS occurs due to solute atoms preferentially coupling with mobile point defect fluxes that migrate and interact with defect sinks. Here, a 304 stainless steel was neutron irradiated up to 47.1 dpa at 320°C. Investigations into the RIS response at specific grain boundary types were utilized to determine the sink characteristics of different boundary types as a function of irradiation dose. A rate theory model built on the foundation of the modified inverse Kirkendall (MIK) model is proposed and benchmarked to the experimental results. This model, termed the GiMIK model, includes alterations in the boundary conditions based on grain boundary structure and expressions for interstitial binding. This investigation, through experiment and modeling, found specific grain boundary structures exhibit unique defect sink characteristics depending on their local structure. Such interactions were found to be consistent across all doses investigated and to have larger global implications, including precipitation of Ni-Si clusters near different grain boundary types.

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Section: Experimental Procedures For Ris Quantificationmentioning

confidence: 99%

Defect sink characteristics of specific grain boundary types in 304 stainless steels under high dose neutron environments

et al. 2015

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“…Channel-grain boundary interaction may also be complex, leading to channel penetration or formation of a highly stressed area [11,12]. During straining at room temperature, channel formation may be accompanied by specific phase transformations at the surface [13]. In addition to channel formation, areas with a high local strain level and significant local misorientation may form at the surface [14].…”

Section: Introductionmentioning

confidence: 99%

Deformation localization and dislocation channel dynamics in neutron-irradiated austenitic stainless steels

Gussev

Field

Busby

2015

Journal of Nuclear Materials

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The dynamics of deformation localization and dislocation channel formation were investigated in situ in a neutron-irradiated AISI 304 austenitic stainless steel and a model 304-based austenitic alloy by combining several analytical techniques including optic microscopy and laser confocal microscopy, scanning electron microscopy, electron backscatter diffraction, and transmission electron microscopy (TEM). Channel formation was observed at ~70% of the polycrystalline yield stress of the irradiated materials (σ 0.2). It was shown that triple junction points do not always serve as a source of dislocation channels; at stress levels below the σ 0.2 , channels often formed near the middle of the grain boundary. For a single grain, the role of elastic stiffness value (Young's modulus) in channel formation was analyzed; it was shown that in the irradiated 304 steels the initial channels appeared in "soft" grains with a high Schmid factor located near "stiff" grains with high elastic stiffness. The spatial organization of channels in a single grain was analyzed; it was shown that secondary channels operating in the same slip plane as primary channels often appeared at the middle or at one-third of the way between primary channels. The twinning nature of dislocation channels was analyzed for grains of different orientation using TEM. In the AISI 304 steel, channels in grains oriented close to <001>||TA (tensile axis) and <101>||TA were twin free and grain with <111>||TA and grains oriented close to a Schmid factor maximum contained deformation twins.

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“…Gussev et al [4] observed deformation twinning within dislocation channels in particular grain orientations of neutron irradiated 304 SS. In an earlier study, the authors also noted the presence of small colonies of strain-induced martensite grains near the steps created by surfacing dislocation channels in these specimens, again in specific grain orientations [10].…”

Section: Introductionmentioning

confidence: 67%

“…For an FCC crystal, the expected slip systems consist of the {111} family of planes and <110> directions. A Schmid factor calculation for the z[025] loading direction predicts that two of the twelve possible slip systems share the highest Schmid factor of 0.493, the (111) plane in the [1][2][3][4][5][6][7][8][9][10] direction and the (-111) plane in the [101] direction. To confirm that the observed slip planes match those with the highest predicted Schmid factor, post-test image analysis was performed using SEM images of a representative compressed pillar.…”

Section: Microcompression Resultsmentioning

confidence: 99%

“…In fact, this phenomenon has been observed in 4-point bend tests of neutron irradiated 304 SS, in which dislocation channels were shown to form in an orientation-dependent manner at as low as 72% of the bulk yield stress [9]. In addition, the presence of deformation twinning and martensite formation in irradiated 304 SS has been shown to have a strong orientation dependence [4,9,10,22]. Studies presently underway, utilizing micro Laue diffraction in an effort to "see inside" a pillar volume during microcompression, suggest that deformation induced martensitic phase transformations do not take place under the current test conditions.…”

Section: Discussionmentioning

confidence: 97%

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Nanoindentation and in situ microcompression in different dose regimes of proton beam irradiated 304 SS

Reichardt

Lupinacci

Frazer

et al. 2017

Journal of Nuclear Materials

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Recent developments in micromechanical testing have allowed for the efficient evaluation of radiation effects in micron-scale volumes of ion-irradiated materials. In this study, both nanoindentation and in situ SEM microcompression testing are carried out on 10 dpa proton beam irradiated 304 stainless steel to assess radiation hardening and radiation-induced deformation mechanisms in the material. Using a focused ion beam (FIB), arrays of 2 μm x 2 μm cross-section microcompression pillars are fabricated in multiple dose regimes within the same grain, providing dose-dependent behavior in a single crystal orientation. Analysis of the microcompression load-displacement data and real-time SEM imaging during testing indicates significant hardening, as well as increased localization of deformation in the irradiated material. Although nanoindentation results suggest that irradiation hardening saturates at low doses, microcompression results indicate that the pillar yield stress continues to rise with dose above 10 dpa in the tested orientation.

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Strain-induced phase transformation at the surface of an AISI-304 stainless steel irradiated to 4.4dpa and deformed to 0.8% strain

Cited by 33 publications

References 20 publications

Defect sink characteristics of specific grain boundary types in 304 stainless steels under high dose neutron environments

Defect sink characteristics of specific grain boundary types in 304 stainless steels under high dose neutron environments

Deformation localization and dislocation channel dynamics in neutron-irradiated austenitic stainless steels

Nanoindentation and in situ microcompression in different dose regimes of proton beam irradiated 304 SS

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