Primary creep regeneration in 10%Cr martensitic steel: In-situ and ex-situ microstructure studies

Li, X.; Holdsworth, S.R.; Kalácska, Szilvia; Balogh, Levente; Park, J.-S.; Sologubenko, Alla S.; Maeder, Xavier; Kabra, Saurabh; Mazza, Edoardo; Hosseini, E.

doi:10.1016/j.matdes.2020.109405

Cited by 8 publications

(5 citation statements)

References 48 publications

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“…6b) shows an overall high dislocation density (of the order of 10 15 m 2 ), comparable to other measurements in similar materials [22,23]. The dislocations are mainly concentrated along lath boundaries, typical to martensitic steels [22]. On the other hand, no significant local increase of the dislocation density is measured in the plasticized zone located between the cracks.…”

Section: Main Textsupporting

confidence: 84%

See 1 more Smart Citation

Investigation of Quasi-Cleavage in a Hydrogen Charged Maraging Stainless Steel

Bestautte¹,

Kalácska

Béchet³

et al. 2022

SSRN Journal

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Section: Main Textsupporting

confidence: 84%

“…The estimated ρ GND map (Fig. 6b) shows an overall high dislocation density (of the order of 10 15 m 2 ), comparable to other measurements in similar materials [22,23]. The dislocations are mainly concentrated along lath boundaries, typical to martensitic steels [22].…”

Section: Main Textsupporting

confidence: 82%

Investigation of Quasi-Cleavage in a Hydrogen Charged Maraging Stainless Steel

Bestautte¹,

Kalácska

Béchet³

et al. 2022

SSRN Journal

View full text Add to dashboard Cite

“…In the unloading process, the stress-strain curve diverges from a straight line. The diverged strain is the pseudoelasticity ε pe , which is due to back transformation from ε-martensite to γ-austenite and a reversible motion of Schockley partial dislocations upon unloading [23,[29][30][31]. After pre-straining, the specimen was re-loaded to 1% and unloaded (black line) to evaluate E SMA (κ 1 ).…”

Section: Resultsmentioning

confidence: 99%

Effect of Phase Changes on the Axial Modulus of an FeMnSi-Shape Memory Alloy

2021

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The axial modulus ESMA(κ) of FeMnSi-based shape memory alloys (FeMnSi-SMAs) is a parameter introduced in this study to characterize the relationship between stress and strain behavior at the early stage of tensile loading. ESMA(κ) can be used to correctly estimate and model the interaction forces between FeMnSi-SMAs and other materials. Unlike the conventional Young’s modulus, which is usually given at room temperature, the ESMA(κ) is evaluated at different temperatures and strongly depends on phase transformation and plastic deformation. This study investigated the evolution of ESMA(κ) during and after pre-straining as well as in the course of the activation processes. The effect of different factors (e.g., phase transformation and plastic deformation) on the magnitude of ESMA(κ) is discussed. The result shows that the ESMA(κ) can differ significantly during activation and thus needs to be modified when interaction forces between FeMnSi-SMAs and other substrates materials (e.g., concrete) must be modeled and evaluated.

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“…Retesting, on the contrary, involves reloading the same (previously tested) disc after DIC imaging for subsequent testing under the same conditions as prior testing. Although fewer specimens are required through disc reuse, softening or hardening effects on creep strain development are of concern [26]. For both methods, the test is stopped when the load is removed, followed by gradual cooling and removal of the crept disc for DIC imaging.…”

Section: Ex Situ Specimen Loading Methodsmentioning

confidence: 99%

“…For example, the retested sample accelerates into the tertiary regime within 3250 s (0.9 h) whereas the interrupted sample (curve (f) in Figure 5, for instance) remained in the primary creep regime for > 6000 s (1.67 h) of testing. This is possibly due to softening effects brought about by primary creep regeneration which causes increased creep rates following an unloading-loading cycle (point (b) in Figure 6a, for instance) as a result of a reduction in dislocation densities [26]. Speckle pattern quality completely degrades for highly strained areas as in the case of Figure 5c where a flat disc of new X20 was subjected to creep loading prior to any preforming.…”

Section: Interrupted Tests Versus Retestsmentioning

confidence: 99%

An Experimental Approach to the Application of Digital Image Correlation to Small Punch Creep Testing

2021

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Deterioration assessment of materials is essential to the continued effective operation of critical components operating, at high temperatures and stresses, in thermal power plants. Within progressive inspection strategies, small punch creep testing (SPCT) presents an effective method for establishing the degree of creep exhaustion of in-service power engineering alloys on account of the small volume of material required (Ø8 mm × 0.5 mm discs). These tests make the application of complex strain fields, analogous to the strain field experienced by the service components, possible. In addition, this work explores the application of a noncontact digital image correlation (DIC) method to the full-field measurement of strains which is not possible through traditional extensometry. The accelerated SPCT tests were performed on 12 % Cr ex-service steels subjected to 600 °C. Experimental methodologies and challenges associated with ex situ DIC-SPCT are discussed including equipment and parameter selection, speckle pattern application, preforming requirements and loading method. It is shown that the developed DIC technique using a stereo microscope, airbrushed speckle patterns, sombrero-preformed discs and interrupted tests can be used to compare surface strain development in various aged forms of the ex-service steel. Such an approach is valuable to understanding strain development in small punch tests and to assist in the comparative damage assessment of ex-service power plant materials.

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Primary creep regeneration in 10%Cr martensitic steel: In-situ and ex-situ microstructure studies

Cited by 8 publications

References 48 publications

Investigation of Quasi-Cleavage in a Hydrogen Charged Maraging Stainless Steel

Investigation of Quasi-Cleavage in a Hydrogen Charged Maraging Stainless Steel

Effect of Phase Changes on the Axial Modulus of an FeMnSi-Shape Memory Alloy

An Experimental Approach to the Application of Digital Image Correlation to Small Punch Creep Testing

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