Effects of Mn, Si and Cr addition on reverse transformation at 1073K from spheroidized cementite structure in Fe–0.6 mass% C alloy

Miyamoto, Gorō; Usuki, Hirokazu; Li, Z.-D.; Furuhara, Tadashi

doi:10.1016/j.actamat.2010.04.045

Cited by 101 publications

(68 citation statements)

References 20 publications

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“…The lever rule has been applied to estimate the volume fraction of austenite from dilatometric data on continuous heating at a constant rate in low carbon steels. Those results have been compared with metallographic measurements and found to be in very good agreement (Almeida et al, 2010;San Martin et al, 2008;Mohanty et al, 2011). This work analyzes the influence of the heating rate on the kinetics austenite formation in the continuous heating of low carbon steel with initial microstructures composed of ferrite and pearlite, ferrite and martensite, and martensite, by using the JMAK equation and by means of dilatometric analysis.…”

Section: Introductionmentioning

confidence: 78%

A study of isochronal austenitization kinetics in a low carbon steel

Lopes

Cota

2014

Rem: Rev. Esc. Minas

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The austenite formation under isochronal conditions in Nb microalloyed low carbon steel was studied by means of dilatometric analysis and the data was adjusted to the Johnson-Mehl-Avrami-Kolmogorov (JMAK) ResumoFoi estudada a formação da austenita em condições isócronas em um aço de baixo carbono e microligado com Nb por meio de análise dilatométrica, com o ajuste dos dados à equação de Johnson-Mehl-Avrami-Kolmogorov (JMAK), para diferentes taxas de aquecimento e para três diferentes microestruturas iniciais. Foi mostrado que a cinética de austenitização da estrutura perlita+ferrita é mais rápida que a da martensita (martensita revenida) à taxa de aquecimento de 0,1 o C/s. Para taxas de aquecimento maiores que 0,1ºC/s, a cinética de austenitização da estrutura martensítica é maior que da estrutura perlita+ferrita. O parâmetro K da equação de JMAK aumenta com a taxa de aquecimento para as três microestruturas prévias e é maior para a microestrutura inicial composta de perlita+ferrita. A baixas taxas de aquecimento, a formação da austenita é controlada pela difusão de carbono, independentemente da microestrutura inicial. A altas taxas de aquecimento, a formação da austenita da microestrutura inicial composta de perlita+ferrita é uma transformação controlada pela interface.Palavras-chave: formação da austenita; cinética; aço baixo carbono.

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Section: Introductionmentioning

confidence: 78%

A study of isochronal austenitization kinetics in a low carbon steel

Lopes

Cota

2014

Rem: Rev. Esc. Minas

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“…Above Ac 3 , h-cementite (M 3 C) and other species will undergo dissolution within austenite in a temperature range whose width varies depending both on the chemical composition of the carbides, and on the heating rate. In fact, Cr is known to enhance cementite stability at high temperature, because retained carbide dissolution in austenite is not controlled by high diffusion rates of interstitial carbon, but by low diffusion rates of substitutional elements at the interfaces ( Ref 25,[37][38][39]. In addition, high heating rates may promote the so-called cementite remnants, which consist of undissolved particles within the austenite matrix up to 1000°C (Ref 40).…”

Section: Transition or Tertiary Carbidesmentioning

confidence: 99%

“…Just below Ac 1 and prior to austenite transformation, the fresh martensitic matrix will decompose into ferrite and hcementite (M 3 C) ( Ref 37,38). Between the points Ac 1 and Ac 3 , the ferrite matrix will be transformed into austenite under an allotropic transformation, while h-cementite will remain mostly undissolved or untransformed, due to the continuous heating conditions ( Ref 25,38,39).…”

Section: Transition or Tertiary Carbidesmentioning

confidence: 99%

Phase Transformations and Crack Initiation in a High-Chromium Cast Steel Under Hot Compression Tests

Tchuindjang

Torres

Flores

et al. 2015

J. of Materi Eng and Perform

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The mechanical behavior of the fully austenitic matrix of high-chromium cast steel (HCCS) alloy is determined by external compression stress applied at 300 and 700°C. The microstructure is roughly characterized toward both optical and scanning electron microscopy analyses. Dilatometry is used during heating from room temperature up to austenitization to study the solid-state phase transformations, precipitation, and dissolution reactions. Two various strengthening phenomena (precipitation hardening and stress-induced bainite transformation) and one softening mechanism (dynamic recovery) are highlighted from compression tests. The influence of the temperature and the carbide type on the mechanical behavior of the HCCS material is also enhanced. Cracks observed on grain boundary primary carbides allow establishing a rough damage model. The crack initiation within the HCCS alloy is strongly dependent on the temperature, the externally applied stress, and the matrix strength and composition.

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“…Also, T. A. Palmer and J. W. Elmer 11 indicated austenite nucleated at sub-boundaries of ferrite. In terms of alloys composition, G. Miyamoto et al 12 discovered that the addition of Mn, Si and Cr elements retarded austenite reformation by decreasing the carbon activity. 15 and found out the addition of boron restricted the growth of austenite grains at high temperatures.…”

Section: Introductionmentioning

confidence: 99%

In situ observation of bainite to austenite transformation of microalloyed high strength steel during simulated welding cycle

Lei

Wang

et al. 2014

Science and Technology of Welding and Joining

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A confocal scanning laser microscope, equipped with a high temperature stage, was used for in-situ observation of the bainite-to-austenite transformation in a micro-alloyed ultra-high strength steel. Austenite grain growth was observed and measured directly from 1040 °C to the peak temperature of 1340 °C during the heating process, as well as the subsequent cooling down to 1040 °C. The grain growth rate versus temperature was analyzed. It was demonstrated that the austenite grains grew up simultaneously by means of grain boundary migration and "grain swallowing" phenomena. The variation in grain growth rate was attributed to the presence of impeding precipitates e.g. carbonitrides Nb,Ti(C,N). The work also showed that coarsening and/or dissolution of carbonitride precipitates, above a certain temperature, led to a fast grain growth. The in-situ observation by confocal scanning laser microscope can provide valuable information on the austenite reformation and final microstructure of weldments.

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Effects of Mn, Si and Cr addition on reverse transformation at 1073K from spheroidized cementite structure in Fe–0.6 mass% C alloy

Cited by 101 publications

References 20 publications

A study of isochronal austenitization kinetics in a low carbon steel

A study of isochronal austenitization kinetics in a low carbon steel

Phase Transformations and Crack Initiation in a High-Chromium Cast Steel Under Hot Compression Tests

In situ observation of bainite to austenite transformation of microalloyed high strength steel during simulated welding cycle

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