Internal stresses and carbon enrichment in austenite of Quenching and Partitioning steels from high energy X-ray diffraction experiments

Allain, Sébastien; Gaudez, Steve; Géandier, Guillaume; Hell, Jean-Christophe; Gouné, Mohamed; Danoix, F.; Soler, Michel; Aoued, Samy; Poulon-Quintin, Angéline

doi:10.1016/j.msea.2017.10.105

Cited by 58 publications

(58 citation statements)

References 28 publications

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“…The 2D diffraction patterns (Debye-Scherrer rings) were then circularly integrated, and each corresponding 1D diffractogram underwent a Rietveld analysis to determine the respective fraction of phases in the sample (bainite and austenite) all along the isothermal treatment. Steel 3 is a model alloy developed in the frame of an ongoing research, and further details of its development and characteristics can be found elsewhere [36,37].…”

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confidence: 99%

“…Such a difference has an important effect in the (∆L/L 0 ) f α b calculations as they rely on estimated lattice parameters. Finally, the theoretical calculations take into account neither the influence of dislocation density, introduced during the transformation [45], nor the internal stresses introduced during cooling to room temperature in the microstructure, as a consequence of the different thermal expansion coefficients of austenite and bainitic ferrite [37].…”

mentioning

confidence: 99%

“…during the transformation [45], nor the internal stresses introduced during cooling to room temperature in the microstructure, as a consequence of the different thermal expansion coefficients of austenite and bainitic ferrite [37]. For all those reasons, normalization, to the maximum of the experimental and calculated (∆L/L ) curves, has proven to minimize such disagreements.…”

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confidence: 99%

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Quantitative Assessment of the Time to End Bainitic Transformation

Santajuana

Eres-Castellanos

Ruiz-Jimenez

et al. 2019

Metals

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Low temperature bainite consists of an intimate mixture of bainitic ferrite and retained austenite, usually obtained by isothermal treatments at temperatures close to the martensite start temperature and below the bainite start temperature. There is widespread belief regarding the extremely long heat treatments necessary to achieve such a microstructure, but still there are no unified and objective criteria to determine the end of the bainitic transformation that allow for meaningful results and its comparison. A very common way to track such a transformation is by means of a high-resolution dilatometer. The relative change in length associated with the bainitic transformation has a very characteristic sigmoidal shape, with low transformation rates at the beginning and at end of the transformation but rapid in between. The determination of the end of transformation is normally subjected to the ability and experience of the “operator” and is therefore subjective. What is more, in the case of very long heat treatments, like those needed for low temperature bainite (from hours to days), differences in the criteria used to determine the end of transformation might lead to differences that might not be assumable from an industrial point of view. This work reviews some of the most common procedures and attempts to establish a general criterion to determine the end of bainitic transformation, based on the differential change in length (transformation rate) derived from a single experiment. The proposed method has been validated by means of the complementary use of hardness measurements, X-ray diffraction and in situ high energy X-ray diffraction.

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confidence: 99%

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confidence: 99%

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Quantitative Assessment of the Time to End Bainitic Transformation

Santajuana

Eres-Castellanos

Ruiz-Jimenez

et al. 2019

Metals

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“…The temperature was regulated and recorded by a thermocouple spot-welded at the center of the sample. The setup was the same as that used in [14].…”

Section: Methodsmentioning

confidence: 99%

“…In these trials the transformation is isothermal, so the austenite carbon content was determined by calculating the relative lattice dilatation ∆a γ between each measured lattice parameter value, a m and a reference lattice parameter determined at the transformation temperature before any bainite has formed, a tr . This difference is proportional to the austenite carbon enrichment ∆C γ as follows [14]:…”

Section: Methodsmentioning

confidence: 99%

The Influence of Vanadium Additions on Isothermally Formed Bainite Microstructures in Medium Carbon Steels Containing Retained Austenite

Pushkareva

Amirkhiz

Allain

et al. 2020

Metals

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The influence of V additions on isothermally formed bainite in medium carbon steels containing retained austenite has been investigated using in-situ high energy X-ray diffraction (HEXRD) and ex-situ electron energy loss spectroscopy (EELS) and energy dispersive X-ray analysis (EDX) techniques in the transmission electron microscope (TEM). No significant impact of V in solid solution on the bainite transformation rate, final phase fractions or on the width of bainite laths was seen for transformations in the range 375-430 • C. No strong influence on the dislocation density could be detected, although quantitative analysis was impeded by ferrite tetragonality. A reduction in the carbon content of retained austenite C γ that is not believed to be due to competition with VC or cementite precipitation was observed. No influence of V on the carbon supersaturation in bainitic ferrite C b could be directly measured, although carbon mass balance calculations suggest C b slightly increases. A beneficial refinement of blocky MA and a corresponding size effect induced enhancement in austenite stability were found at the lowest transformation temperature. Overall, V additions result in a slight increase in strength levels.

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Fundamentals and applications of nanoparticles for ultrasound‐based imaging and therapy

et al. 2020

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Ultrasonography (US) is frequently applied in clinical imaging because of its inherent merits compared with those of other imaging methods. Nanoparticle (NP)‐based imaging and therapeutic modalities have been widely used because of their unique functionalities and high performance. The report is mainly about the classifications and applications of NPs for US‐based theranostic biomedicine. The US‐based applications include single‐modality US imaging, multimodality US imaging, high‐intensity focused US, US‐triggered drug release, US‐enhanced gene transfection, and US‐irradiated sonodynamic therapy. In addition, current challenges, including the biological effects and biosafety, are discussed in this interview. NPs have tremendous potential as a US‐based theranostic tool and have revealed a new direction in cancer therapy.

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Internal stresses and carbon enrichment in austenite of Quenching and Partitioning steels from high energy X-ray diffraction experiments

Cited by 58 publications

References 28 publications

Quantitative Assessment of the Time to End Bainitic Transformation

Quantitative Assessment of the Time to End Bainitic Transformation

The Influence of Vanadium Additions on Isothermally Formed Bainite Microstructures in Medium Carbon Steels Containing Retained Austenite

Fundamentals and applications of nanoparticles for ultrasound‐based imaging and therapy

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