Influence of cast part size on macro- and microsegregation patterns in a high carbon high silicon steel

Basso, Alejandro Daniel; Toda‐Caraballo, Isaac; San-Martín, David; Caballero, Francisca G.

doi:10.1016/j.jmrt.2020.01.052

Cited by 17 publications

(14 citation statements)

References 46 publications

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“…It is important to point out that in this kind of steel, the etching response/contrast of the dendritic and interdendritic regions is different due to the microsegregation. This phenomenon was observed and reported by the authors in a previous work [29]. Next, the surfaces were lightly re-polished to remove the etched superficial layers with a 1 µm diamond cloth but preserving the indentations.…”

Section: Microstructural Characterizationsupporting

confidence: 74%

“…A high C content promotes the formation of bainite at low temperatures, obtaining very high strength microstructures [30][31][32]. The microsegregation of this steel was studied in a previous work [29], and it was concluded that a mean Si content of 2.2 wt.% ensures suppression of the carbide precipitation from austenite [33]. Finally, Mn and Cr were added in order to increase the steel hardenability [23,30,31,34].…”

Section: Methodsmentioning

confidence: 98%

“…The authors of this work have begun to carry out studies in this line of research, particularly in subjects related to the segregation phenomena present in HC-HSi steel. In a previous work, the authors have investigated in detail the macro and microsegregation patterns of Cr, Mn, and Si in a HC-HSi steel, with an appropriate chemical composition to obtain bainitic structures and casted using different keel block sizes [29]. The results have revealed that all these elements segregate into the interdendritic zones during the primary formation of austenite from the melt.…”

Section: Introductionmentioning

confidence: 99%

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Effect of Microsegregation and Bainitic Reaction Temperature on the Microstructure and Mechanical Properties of a High-Carbon and High-Silicon Cast Steel

Basso

Eres-Castellanos

Tenaglia

et al. 2021

Metals

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Bainitic microstructures obtained in high-carbon (HC) and high-silicon (HSi) steels are currently of great interest. Microstructural evolution and the bainitic transformation kinetics of a high-carbon and high-silicon cast steel held at 280, 330, and 380 °C was analyzed using dilatometry, X-ray diffraction, optical and scanning electron microscopy, and electron backscatter diffraction (EBSD). It is shown that the heterogeneous distribution of silicon (Si), manganese (Mn), and chromium (Cr) associated to microsegregation during casting has a great impact on the final microstructure. The transformation starts in the dendritic zones where there is a lower Mn concentration and then expands to the interdendritic ones. As Mn reduces the carbon activity, the interdendritic areas with a higher Mn concentration are enriched with carbon (C), and thus, these zones contain a greater amount of retained austenite plus martensite, resulting in a heterogeneous microstructure. Higher transformation temperatures promote higher amounts of residual austenite with poor thermal/mechanical stability and the presence of martensite in the final microstructure, which has a detrimental effect on the mechanical properties. Tensile tests revealed that the ultra-fine microstructure developed by the transformation at 280 °C promotes very high values of both tensile and yield stress (≈1.8 GPa and 1.6 GPa, respectively), but limited ductility (≈2%).

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Section: Microstructural Characterizationsupporting

confidence: 74%

Section: Methodsmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Effect of Microsegregation and Bainitic Reaction Temperature on the Microstructure and Mechanical Properties of a High-Carbon and High-Silicon Cast Steel

Basso

Eres-Castellanos

Tenaglia

et al. 2021

Metals

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“…A Fe-0.8C-2Si-1Mn-1Cr (in wt. %) alloy has been selected based on its low transformation temperatures to bainite as reported in the literature [29][30][31][32][33][34][35][36][37][38]. The C content has been fixed near 0.8 wt.…”

Section: Materials and Casting Proceduresmentioning

confidence: 99%

“…In a previous research, the authors have investigated in detail the macro-and microsegregation patters obtained in a HC-HSi steel, which have been casted using different keel block sizes [31]. The presence of microsegregation, would alter the distribution of elements like Si, Mn, and Cr, influencing the formation of martensite after quenching as well as the nucleation and growth of the bainite during austempering treatments.…”

Section: Introductionmentioning

confidence: 99%

Effect of the Microsegregation on Martensitic and Bainitic Reactions in a High Carbon-High Silicon Cast Steel

Basso

Toda‐Caraballo

Eres-Castellanos

et al. 2020

Metals

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Casting processes show some weaknesses. A particular problem is presented when the workpiece needs to be subjected to heat treatments to achieve a desired microstructure. This problem arises from the microsegregation phenomena typically present in cast parts. The effect of the microsegregation on the martensitic and bainitic transformations has been investigated in a high carbon-high silicon cast steel, with the approximate composition Fe-0.8C-2Si-1Mn-1Cr (in wt. %), which was poured into 25 mm keel block-shaped sand molds. The microsegregation maps of Cr, Si, and Mn characterized by electron probe microanalysis (EPMA) show that interdendritic regions are enriched while dendrites are impoverished in these elements, implying that their partition coefficients are lower that the unity (k < 1). As-quenched martensitic and austempered bainitic microstructures (at 230 °C) were obtained and analyzed after applying an austenitization heat treatment at 920 °C (holding for 60 min). The thermal etching method used to reveal the prior austenite grain size showed a bimodal grain size distribution, with larger grains in the dendritic regions (≈22.4 µm) than in the interdendritic ones (≈6.4 µm). This is likely due to both the microsegregation and the presence of small undissolved cementite precipitates. Electron Backscatter Diffraction (EBSD) analysis carried out on the martensitic microstructure do not unveil any differences in misorientation distribution frequency and block size between the dendritic and interdendritic zones related to the microsegregation and bimodality of the austenite grain size. On the contrary, the bainitic transformation starts earlier (incubation time of 80 min), proceeds faster and bainitic ferrite plates are longer in the dendritic zones, were prior austenite grains are larger and impoverish in solute. The presence of these microsegregation pattern leads to the non-uniform development of the bainitic reaction in cast parts, modifying its kinetics and the resulting microstructures, which would probably have a major impact on the mechanical properties.

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Influence of Cooling Parameters on the Microstructure and Primary Carbide Precipitation in GCr15 Steel

Jiang

Zhang

2021

steel research int.

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With the high temperature confocal laser scanning microscope applied, the effect of cooling rate, temperature interval, and cooling mechanism on the solidification microstructure and primary carbide participation in GCr15 steel are investigated. The solute distribution in interdendritic segregation and participation carbide are analyzed by electron probe microanalysis. The results show that solute concentrate is low in the dendrite zone but it increases clearly in the segregation zone. The carbon concentration in the precipitation can reach 6.49%, which means the primary carbide is M3C. In the heating process, the segregation zone and carbide participation melt first before it reaches the solidus temperature. During the solidification stage, the microstructure is refined and the size of primary carbide is reduced with a higher cooling rate, but the number density of primary carbide is increased. Moreover, it is found that the microstructure is formed in the earlier solidification, before the temperature declines to 1673 K. While the primary carbide participates in the later cooling stage and the transition temperature for the primary carbide is 1503 K. In addition, the primary carbide size can be reduced with the cooling rate larger than 300 K min−1 in the subsequent cooling stage.

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Influence of cast part size on macro- and microsegregation patterns in a high carbon high silicon steel

Cited by 17 publications

References 46 publications

Effect of Microsegregation and Bainitic Reaction Temperature on the Microstructure and Mechanical Properties of a High-Carbon and High-Silicon Cast Steel

Effect of Microsegregation and Bainitic Reaction Temperature on the Microstructure and Mechanical Properties of a High-Carbon and High-Silicon Cast Steel

Effect of the Microsegregation on Martensitic and Bainitic Reactions in a High Carbon-High Silicon Cast Steel

Influence of Cooling Parameters on the Microstructure and Primary Carbide Precipitation in GCr15 Steel

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