Microstructure and dislocation arrangements in Sanicro 25 steel fatigued at ambient and elevated temperatures

Heczko, Milan; Polák, Jaroslav; Kruml, Tomáš

doi:10.1016/j.msea.2016.10.076

Cited by 51 publications

(49 citation statements)

References 30 publications

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“…The saturated amplitude of plastic strain was evaluated. Further information about the testing conditions can be found elsewhere [4,5,10].…”

Section: Mechanical Testsmentioning

confidence: 99%

“…However, detailed investigation of mechanisms governing high temperature cyclic behavior is still missing. Polák and coworkers [4,5,10,11] have reported exceptional cyclic hardening, during low cycle fatigue at 700°C leading to remarkably high saturated cyclic stress. They have hypothesized that fine scale precipitates and their interaction with mobile dislocations may play a significant role in cyclic strengthening.…”

Section: Introductionmentioning

confidence: 99%

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On the origin of extraordinary cyclic strengthening of the austenitic stainless steel Sanicro 25 during fatigue at 700 °C

et al. 2017

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The origin of the extraordinary strengthening of the highly-alloyed austenitic stainless steel Sanicro 25 during cyclic loading at 700°C was investigated by use of advanced scanning transmission electron microscopy (STEM). Along with substantial change of dislocation structure, nucleation of two distinct populations of nanoparticles was revealed. Fully coherent Cu-rich nanoparticles were observed homogeneously dispersed with high density along with nanometer-sized incoherent NbC carbides precipitating on dislocations during cyclic loading. Probe-corrected HAADF STEM imaging was used to characterize the atomic structure of nanoparticles. Compositional analysis was conducted using both EELS and high spatial resolution EDS. High temperature exposure induced precipitation of a high density of coherent Cu-rich nanoparticles while strain-induced nucleation of incoherent NbC nanoparticles leads to retardation of dislocation movement. The pinning effects https://ntrs.nasa.gov/search.jsp?R=20190000303 2019-02-10T17:10:39+00:00Z and associated obstacles to dislocation motion prevent recovery and formation of the localized lowenergy cellular structures. As a consequence, the alloy exhibits remarkable cyclic hardening at elevated temperature.

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“…The saturated amplitude of plastic strain was evaluated. Further information about the testing conditions can be found elsewhere [4,5,10].…”

Section: Mechanical Testsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

On the origin of extraordinary cyclic strengthening of the austenitic stainless steel Sanicro 25 during fatigue at 700 °C

et al. 2017

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“…Contrary to 316L steels, Sanicro 25 has higher tendency to formation of planar dislocation structures during fatigue at ambient temperature mainly as a result of its chemical composition . The thickness of the PSBs is around 250 nm, what is 4 times less when compared with the thickness of PSBs in 316L steel (1 μm) and 5 times less when compared with the thickness of PSB of copper (more than 1 μm) .…”

Section: Discussionmentioning

confidence: 94%

“…Several types of precipitates were found within the microstructure of Sanicro 25 . Mostly, particles of Z‐phase rich in Nb, N, and Cr are found both at grain boundaries and in the interior of larger grains (see Figure B).…”

Section: Methodsmentioning

confidence: 99%

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Initiation and growth of short fatigue cracks in austenitic Sanicro 25 steel

Mazánová

Polák

2018

Fatigue Fract Eng Mat Struct

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Austenitic heat‐resistant stainless steel Sanicro 25, often used in energy production installations, was cyclically strained at room temperature, and initiation and growth of short fatigue cracks have been studied. Cylindrical specimens with pre‐existing shallow notch were cyclically strained under constant total strain amplitudes, while the surface relief, crack initiation, and short crack growth were observed, in‐situ, using optical and electron microscopes. Persistent slip markings were found to be the principal locations where natural fatigue cracks initiated. The character of the crack paths of short cracks was studied using SEM and EBSD techniques. The results exhibit prevailing transgranular crack growth, ie, along the persistent slip markings within the grains. The growth of the largest cracks in the central part of the shallow notch was measured for different applied strain amplitudes. Because the coalescence of initiated cracks plays a significant role during crack growth, the use of the “equivalent crack” concept gives adequate results in the description of the crack growth rate. The crack growth law of short cracks was established and compared with the Manson‐Coffin law of the material.

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Study on Diversified Carbide Precipitation in High‐Strength Low‐Alloy Steel during Tempering

Wei

Zhou

Fang

et al. 2021

steel research int.

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Herein, the precipitation and mechanical properties of high-strength low-alloy steel (Q960E) under different tempering temperatures from 560 to 640 C are investigated. Diversified precipitations (including MC, M 3 C, M 23 C 6 , and M 7 C 3 ) are formed during tempering. The size of the M 3 C, M 23 C 6 , and M 7 C 3 precipitates increases, as the temperature increases, and the precipitates are gradually spheroidized with an average size of less than 100 nm. MC-type precipitates (where M ¼ Nb and Ti) are produced at different tempering temperatures. When tempered at 600 C, Q960E steel exhibits excellent mechanical properties, including a high strength and elongation with a good impact performance. At 600 C, a large number of fine MC carbides with an average size of less than 25 nm are formed. MC and matrix exhibit the Baker-Nutting orientation relationship. Edge dislocations exist in the transition region between the MC nanophase and the matrix. These dislocations reduce the mismatch degree between the MC nanophase and the matrix and promote MC nucleation. Meanwhile, the steel retains many low-angle grain boundaries when tempered at 600 C, which is beneficial to its high strength.

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Microstructure and dislocation arrangements in Sanicro 25 steel fatigued at ambient and elevated temperatures

Cited by 51 publications

References 30 publications

On the origin of extraordinary cyclic strengthening of the austenitic stainless steel Sanicro 25 during fatigue at 700 °C

On the origin of extraordinary cyclic strengthening of the austenitic stainless steel Sanicro 25 during fatigue at 700 °C

Initiation and growth of short fatigue cracks in austenitic Sanicro 25 steel

Study on Diversified Carbide Precipitation in High‐Strength Low‐Alloy Steel during Tempering

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