Austenite films in bainitic microstructures

Chang, L. C.; Bhadeshia, H. K. D. H.

doi:10.1179/026708395790165462

Cited by 50 publications

(43 citation statements)

References 4 publications

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“…This volume is sometimes assumed constant with temperature in the literature, with dimensions of 0.2 9 10 9 10 lm 3 , [26] but investigations have shown that the average volume of a bainitic subunit actually depends on different factors, such as temperature, austenite strength, and driving force, as described by Singh and Bhadeshia. [27] Parker [28] empirically modeled the bainitic subunit thickness as a temperature-dependent parameter, based on previous experimental work of Chang and Bhadeshia [29] on silicon-rich steels with carbon contents between 0.095 and 0.5 wt pct, isothermally treated between 523 K and 773 K (250°C and 500°C). The thickness of bainitic subunits, z¢, was then modeled as…”

Section: Isothermal Transformation Kineticsmentioning

confidence: 99%

Effect of Prior Athermal Martensite on the Isothermal Transformation Kinetics Below M s in a Low-C High-Si Steel

Navarro-López

Sietsma

Santofimia

2015

Metall Mater Trans A

109

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A. NAVARRO-LÓ PEZ, J. SIETSMA, and M.J. SANTOFIMIA Thermomechanical processing of Advanced Multiphase High Strength Steels often includes isothermal treatments around the martensite start temperature (M s ). It has been reported that the presence of martensite formed prior to these isothermal treatments accelerates the kinetics of the subsequent transformation. This kinetic effect is commonly attributed to the creation of potential nucleation sites at martensite-austenite interfaces. The aim of this study is to determine qualitatively and quantitatively the effect of a small volume fraction of martensite on the nucleation kinetics of the subsequent transformation. For this purpose, dilatometry experiments were performed at different temperatures above and below the M s temperature for athermal martensite in a low-carbon high-silicon steel. Microstructural analysis led to the identification of the isothermal decomposition product formed above and below M s as bainitic ferrite. The analysis of the transformation processes demonstrated that the initial stage of formation of bainitic ferrite at heat treatments below M s is at least two orders of magnitude faster than above M s due to the presence of martensite.

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Section: Isothermal Transformation Kineticsmentioning

confidence: 99%

Effect of Prior Athermal Martensite on the Isothermal Transformation Kinetics Below M s in a Low-C High-Si Steel

Navarro-López

Sietsma

Santofimia

2015

Metall Mater Trans A

109

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“…It was found that the activation energy for bainite nucleation is proportional to the driving force available for transformation [15,16]. According to differential scanning calorimetry measurement results, sample A2 temperature is expected to be higher than the sample A4 temperature for Cu-9.97%Al-4.62%Mn alloy.…”

Section: Resultsmentioning

confidence: 99%

Effect of Deformation on the Transformation Temperatures of Martensite and Bainite Structures in Cu-9.97%Al-4.62%Mn Alloy

Aldırmaz

2016

Acta Phys. Pol. A

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At present study of Cu-9.97%Al-4.62%Mn alloy system is used. Some physical properties of martensitic and bainite phase transformatios in Cu-9.97%Al-4.62%Mn (wt%) alloy were investigated by means of scanning electron microscopy and differential scanning calorimetry. In scanning electron microscope observations of Cu-9.97%Al-4.62%Mn alloy were noted two kinds of martensitic phases. These phases were defined as β 1 (M18R) and γ 1 (2H) martensites structures. According to differential scanning calorimetry measurement results, the deformation induced temperature is expected to be higher than the thermally induced temperature in Cu-9.97%Al-4.62%Mn alloy for martensite and bainite structures.

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“…The TEM observations revealed that after austempering process the microstructure of the ADI matrix is composed of thin ferrite plates separated by thin layers of austenite. The thickness of the ferrite plates and of the austenite layers, was determined according to the following stereological formula [11]:…”

Section: Methodsmentioning

confidence: 99%

The Comparative Study of the Microstructure and Phase Composition of Nanoausferritic Ductile Iron Alloy Using SEM, TEM, Magnetometer, and X-Ray Diffraction Methods

et al. 2017

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In this paper the microstructure and phase composition of ausferritic ductile iron alloy were investigated by scanning electron microscopy, transmission electron microscopy and X-ray diffraction methods. In order to obtain the nanoausferritic microstructure in the alloy, the austempering heat treatment was performed at relatively low temperature. As a result, a specific kind of microstructure, containing nanocrystalline ausferrite and retained austenite blocks, was obtained in each heat-treated sample. The volume fractions of phases were determined using different methods: MicroMeter software for scanning electron micrographs, stereological analysis for transmission electron micrographs, quantitative analysis of the X-ray diffraction spectra and magnetometer measurements. All methods revealed a high amount of retained austenite which varied as a function of the austempering treatment parameters. It was shown that the quantitative phase composition measured by X-ray diffraction and magnetometer, in all samples investigated, differs significantly from the stereological measurements and image analysis performed through the MicroMeter software. The possible reasons of the observed differences were discussed.

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Austenite films in bainitic microstructures

Cited by 50 publications

References 4 publications

Effect of Prior Athermal Martensite on the Isothermal Transformation Kinetics Below M s in a Low-C High-Si Steel

Effect of Prior Athermal Martensite on the Isothermal Transformation Kinetics Below M s in a Low-C High-Si Steel

Effect of Deformation on the Transformation Temperatures of Martensite and Bainite Structures in Cu-9.97%Al-4.62%Mn Alloy

The Comparative Study of the Microstructure and Phase Composition of Nanoausferritic Ductile Iron Alloy Using SEM, TEM, Magnetometer, and X-Ray Diffraction Methods

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