Dependence of solute carbon concentration on electrical resistivity of retained austenite

Uranaka, Shohei; Nishimura, Chisa; Hirashima, Issei; Maeda, Takuya; Masumura, Takuro; Kawamoto, Y.; Shirahata, Hiroyuki; Uemori, Ryuji

doi:10.1016/j.scriptamat.2022.114791

Cited by 5 publications

(4 citation statements)

References 10 publications

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“…This suggests that C partitioning into retained austenite accelerates the decrease in C sol in martensitic matrix. 30) For specimens where retained austenite is not present, C sol and X sol decreased gradually with similar rates.…”

Section: Change In Hardness and Microstructure Duringmentioning

confidence: 88%

Quantitative Analysis of Hardening Due to Carbon in Solid Solution in Martensitic Steels

et al. 2023

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The relationship between hardness and solute carbon concentration estimated via electrical resistivity measurement was investigated in as-quenched and tempered martensitic steels containing carbon of 0.3-0.6 mass%. As a result of corelating the amount of hardening due to carbon in solid solution with the solute carbon concentration, by the calculation to subtract precipitation strengthening, grain refinement strengthening, dislocation strengthening, and softening due to retained austenite from the total strengthening, we derived an equation of solid solution strengthening, where the hardening increases proportionally to the 1/2 or 2/3 power of the solute carbon concentration. It was confirmed that the effects of the factors other than solid solution strengthening due to carbon on hardness are relatively small in tempered specimens when the tempering temperature is less than 673 K; therefore, the change in hardness in tempered martensitic steels can be mostly explained by solute carbon concentration regardless of carbon content.

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Section: Change In Hardness and Microstructure Duringmentioning

confidence: 88%

Quantitative Analysis of Hardening Due to Carbon in Solid Solution in Martensitic Steels

et al. 2023

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“…In addition, the α'martensite and ε-martensite shapes are not plate-like, but granular with a small aspect ratio. It was reported that such a unique microstructure was formed via a two-step γ→ε→α' martensitic transformation during quenching; plate-like ε-martensite was initially formed in austenite grains, and then fine α'-martensite nucleated inside the ε-martensite 6) . Figure 2 shows the neutron line profile of the as-quenched specimen and the diffraction peak position of each phase, calculated using RTA.…”

Section: Microstructure Of As-quenched Specimenmentioning

confidence: 99%

Reverse Transformation Behavior in Multi-phased Medium Mn Martensitic Steel Analyzed by <i>in-situ</i> Neutron Diffraction

et al. 2024

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The reverse transformation behavior during heating in Fe-10%Mn-0.1%C (mass%) martensitic alloy consisting of α'-martensite, ε-martensite and retained austenite was investigated using the in-situ neutron diffraction. When the temperature was elevated with a heating rate of 10 K/s, the ε→γ reverse transformation occurred first at the temperature range of 535-712 K, where Fe and Mn hardly diffused.In the temperature range where the ε→γ reverse transformation occurred, the full width at half maximum of the 200γ peak increased, indicating that the austenite reversed from ε-martensite contains high-density dislocations. In addition, the transformation temperature hardly depends on the heating rate and the crystal orientation of the reversed austenite was identical to that of the prior austenite (austenite memory), which suggests that the ε→γ reverse transformation would proceed through the displacive mechanism. After completion of the ε→γ transformation, the α'→γ reverse transformation occurred at the temperature range of 842-950 K. When the heating rate is low (<10 K/s), the reverse transformation start temperature significantly depends on the heating rate. It could be because the diffusional reverse transformation accompanying the repartitioning of Mn occurs. On the other hand, a higher heating rate (≥10 K/s) resulted in the disappearance of the heating rate dependence. This was probably due to the change in the transformation mechanism to the massive-type transformation, which is diffusional transformation without repartitioning of Mn.

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“…where ρ α' and ρ γ are electrical resistivities of martensite and retained austenite, respectively. In a previous study, the relationship between ρ γ and C sol in retained austenite was formulated using as-quenched Fe-2 mass% Mn-0.5 mass% Si-(0.3-0.9) mass% C-10 mass% Ni alloys, as follows: 13) U J m mm m ass sol…”

Section: Microstructure Evaluationmentioning

confidence: 99%

“…................ (12). .......................... (13). where P T FeCCE is the chemical potential of iron in martensite; chemical potentials of C in martensite and austenite, respectively; and G(Fe 3 C) is the free energy of cementite.…”

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confidence: 99%

Effects of Retained Austenite upon Softening during Low-temperature Tempering in Martensitic Carbon Steels

Uranaka,

Takanashi,

Maeda

et al. 2024

ISIJ Int.

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The effects of retained austenite upon softening during low-temperature tempering at 373 K were investigated using martensitic carbon steels with and without retained austenite. To increase the amount of retained austenite, 10 mass% Ni was added to the base carbon steel (Fe-0.3C alloy). During tempering, the hardness decreased more rapidly in the Ni-added steel containing 6 vol.% retained austenite than in the base steel without retained austenite. Analyses of the microstructure and the carbon content in the solid solution (i.e., the solute carbon concentration) revealed that the retained austenite tended to suppress carbide precipitation and significantly reduced the solute carbon concentration in the martensitic matrix. We demonstrated that retained austenite acts as an effective absorption site for solute carbon in the martensitic matrix; however, the partitioned carbon is unevenly localized near the martensite/austenite interface, owing to the poor diffusivity at 373 K. KEY WORDS: martensite; retained austenite; low-temperature tempering; hardness; solute carbon concentration; electrical resistivity measurement.

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Dependence of solute carbon concentration on electrical resistivity of retained austenite

Cited by 5 publications

References 10 publications

Quantitative Analysis of Hardening Due to Carbon in Solid Solution in Martensitic Steels

Quantitative Analysis of Hardening Due to Carbon in Solid Solution in Martensitic Steels

Reverse Transformation Behavior in Multi-phased Medium Mn Martensitic Steel Analyzed by <i>in-situ</i> Neutron Diffraction

Effects of Retained Austenite upon Softening during Low-temperature Tempering in Martensitic Carbon Steels

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