Spherical nanoindentation of proton irradiated 304 stainless steel: A comparison of small scale mechanical test techniques for measuring irradiation hardening

Weaver, Jordan S.; Pathak, Siddhartha; Reichardt, Ashley; Vo, H.T.; Maloy, Stuart A.; Hosemann, Peter; Mara, Nathan A.

doi:10.1016/j.jnucmat.2017.06.031

Cited by 42 publications

(9 citation statements)

References 85 publications

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“…This has enabled the measurement of the local indentation yield strengths in individual grains of deformed polycrystalline metallic samples 26 – 28 , and across their grain boundaries 29 , which in turn can be related to percentage increases in the local slip resistances from their fully annealed conditions. Recent reports have also used these and other related techniques for studying irradiated nuclear materials 15 , 30 , 31 . In this communication, we apply these methods to indentations on ion-irradiated metallic materials, and compare their relative mechanical behavior to the unirradiated state.…”

Section: Introductionmentioning

confidence: 99%

Probing nanoscale damage gradients in ion-irradiated metals using spherical nanoindentation

Pathak

Kalidindi

Weaver

et al. 2017

Sci Rep

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We discuss and demonstrate the application of recently developed spherical nanoindentation stressstrain protocols in characterizing the mechanical behavior of tungsten polycrystalline samples with ionirradiated surfaces. It is demonstrated that a simple variation of the indenter size (radius) can provide valuable insights into heterogeneous characteristics of the radiation-induced-damage zone. We have also studied the effect of irradiation for the different grain orientations in the same sample.Materials with modified surfaces -either as a consequence of a graded microstructure or due to an intentional alteration of the surface such that its physical, chemical or biological characteristics are different from the bulk of the material -are of increasing interest for a variety of applications such as enhanced wear and corrosion resistance, superior thermal and biomedical properties, and higher fracture toughness 1,2 . In some cases such gradations at the surface may also be caused unintentionally as a consequence of the service life of the material, such as in wear applications 3 or irradiated materials which show varying degrees of radiation damage that change with depth, location of radiation source, etc.4 . Quantifying the resulting property gradations poses a significant challenge, especially when the changes occur over small (sub-micrometer) depths. In this communication, we present a novel indentation approach, which together with the corresponding local structure information obtained from electron back-scattered diffraction (EBSD), allows us to probe nanoscale surface modifications in solid materials and quantify the resulting changes in its mechanical response.The study of mechanical degradation in the surface layers of ion-irradiated materials is an example of one such outstanding challenge for which few practically viable solutions 4-7 exist. In materials undergoing irradiation in reactor or spacecraft applications, the resulting damage is often highly heterogeneous (with strong gradients normal to the surface) depending on component location as well as the nature of the irradiation source itself. In nuclear materials research, reactor conditions can be mimicked using ion beams where large amounts of radiation damage (several displacements per atom (dpa)) are imparted in relatively short time spans of hours or days that would require months or years to achieve in reactor conditions [8][9][10] . However, the volume of ion-irradiated material is limited by the beam energy to depths of fractions of a micron to several microns, making the investigation of bulk mechanical properties very difficult. A key challenge then becomes: "How can we study the mechanical response of materials with varying degrees of damage over scales of only a few hundreds of nanometers in such a way that the data can be related to bulk values?" The very small thickness of irradiated material, high level of damage heterogeneity, sensitivity to sample preparation techniques, and the time and effort needed for sample preparation and testi...

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Section: Introductionmentioning

confidence: 99%

Probing nanoscale damage gradients in ion-irradiated metals using spherical nanoindentation

Pathak

Kalidindi

Weaver

et al. 2017

Sci Rep

Self Cite

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“…An example indentation stress-strain curve extracted using the above protocols presented in Figure 3c. The spherical nanoindentation stress-strain protocols described above have been validated extensively in both experiments [53][54][55][56][57][58][59][60][61] and numerical simulations (performed using finite element models) [96][97][98][99]. As a result of these prior validations, we are now fairly confident in obtaining highly reproducible indentation stress-strain curves on a broad variety of material samples.…”

Section: Of 24mentioning

confidence: 90%

“…The large variations in the reported hardness data have hindered attempts aimed at extracting quantitative physical insights that could guide the rational design of DP process histories to achieve desirable combinations of bulk properties. In recent work [53][54][55][56][57][58][59][60][61], it has been demonstrated that indentation yield strength is a much more reproducible and reliable measure of the intrinsic plastic strength of the microscale constituents in a heterogeneous material, and could be estimated from the recently established spherical indentation stress-strain protocols [62,63]. Using this analysis method, it has been shown [57] that the indentation yield strength is very sensitive to The discussion above points out the difficulties encountered in the optimization of the processing of DP steels to meet the desired combination of properties [1,35,36].…”

Section: Introductionmentioning

confidence: 99%

New Insights into the Microstructural Changes During the Processing of Dual-Phase Steels from Multiresolution Spherical Indentation Stress–Strain Protocols

Khosravani

Caliendo

Kalidindi

2019

Metals

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In this study, recently established multiresolution spherical indentation stress-strain protocols have been employed to derive new insights into the microstructural changes that occur during the processing of dual-phase (DP) steels. This is accomplished by utilizing indenter tips of different radii such that the mechanical responses can be evaluated both at the macroscale (reflecting the bulk properties of the sample) and at the microscale (reflecting the properties of the constituent phases). More specifically, nine different thermo-mechanical processing conditions involving different combinations of intercritical annealing temperatures and bake hardening after different amounts of cold work were studied. In addition to demonstrating the tremendous benefits of the indentation protocols for evaluating the variations within each sample and between the samples at different material length scales in a high throughput manner, the measurements provided several new insights into the microstructural changes occurring in the alloys during their processing. In particular, the indentation measurements indicated that the strength of the martensite phase reduces by about 37% when quenched from 810 • C compared to being quenched from 750 • C, while the strength of the ferrite phase remains about the same. In addition, during the 10% thickness reduction and bake hardening steps, the strength of the martensite phase shows a small decrease due to tempering, while the strength of the ferrite increases by about 50% by static aging.

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“…The sixth and seventh columns indicate the results of the statistical test χ 2 in accordance with the following formula: by plastic slip, twinning, or martensitic transformation. The size effect occurs when there are insufficient dislocation sources available in the volume tested such that large stresses are required to initiate plasticity, followed by continued plasticity at much lower stresses [21]. Figures 3 and 4 show the microstructure of tested materials for mini-specimens.…”

Section: Materials and Chemical Compositionmentioning

confidence: 99%

Statistical Size Effect in Fatigue Properties for Mini-Specimens

Tomaszewski

2020

Materials

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The study verifies the sensitivity of selected construction materials (S235JR structural steel and 1.4301 stainless steel) to the statistical size effect. The P–S–N curves were determined experimentally under high-cycle fatigue conditions for two specimen sizes (mini-specimen and standard specimen). The results were analyzed using a probabilistic model of the three-parameter Weibull cumulative distribution function. The analysis included the evaluation of the technological process effects on the results based on the material microstructure near the surface layer and the macro-fractography. The differences in the susceptibility to the size effect validated the applicability of the test method to mini-specimen and showed different populations of the distribution of critical material defects.

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Spherical nanoindentation of proton irradiated 304 stainless steel: A comparison of small scale mechanical test techniques for measuring irradiation hardening

Cited by 42 publications

References 85 publications

Probing nanoscale damage gradients in ion-irradiated metals using spherical nanoindentation

Probing nanoscale damage gradients in ion-irradiated metals using spherical nanoindentation

New Insights into the Microstructural Changes During the Processing of Dual-Phase Steels from Multiresolution Spherical Indentation Stress–Strain Protocols

Statistical Size Effect in Fatigue Properties for Mini-Specimens

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