Kinetics of austenite growth and bainite transformation during reheating and cooling treatments of high strength microalloyed steel produced by sub-rapid solidification

Wang, Wanlin; Wang, Lankun; Lyu, Peisheng

doi:10.1007/s12613-022-2548-7

Cited by 8 publications

(1 citation statement)

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“…During the early stages of the austempering process, a carbon concentration gradient is likely present in the blocky untransformed austenite. [5,40,41] Specifically, the carbon content near the bainite/austenite interface could be much higher than that within the block's interior. It is reported that carbon content near the bainite/austenite interface is close to partitioning local equilibrium/negligible partitioning local equilibrium line (≈1.33 wt %, calculated using the TCFE8 database of Thermo-calc), [5] while the carbon concentration inside the blocky austenite can be calculated by the following method.…”

Section: Microstructural Evolution During Austempering and Temperingmentioning

confidence: 99%

Comparison of Microstructure and Mechanical Properties of a High‐Carbon Bainitic Steel Treated by Long‐Time Bainitic Austempering and Short‐Time Austempering Plus Tempering Processes

Wang,

Gao,

Gui

et al. 2024

steel research int.

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Herein, the microstructure and mechanical properties of a high‐carbon bainitic steel treated by long‐time bainitic austempering and short‐time austempering plus tempering processes are compared. The multiphase microstructures are characterized by dilatometry, X‐ray diffraction, scanning electron microscopy, and transmission electron microscopy to correlate with mechanical properties. Results show that although long‐time austempering treatment can reduce the volume fraction of brittle martensite, no significant improvement is observed in fracture damage resistance. Besides, the cementite is prone to precipitation from the austenite at the later period of the long‐time austempering process. The cementite precipitation in austenite decreases the carbon content in retained austenite (RA) and consequently reduces the mechanical stability of RA. In contrast, the cementite has not been able to precipitate from austenite after short‐time austempering treatment, whereas the martensite is softened and the stability of RA is improved during subsequent tempering. Therefore, excellent mechanical properties are obtained in the samples treated by short‐time austempering plus tempering process: ultimate tensile strength, 1489 MPa, yield strength, 1014 MPa, total elongation, 33.2%, and the product of strength and elongation (PSE) of 48.4 GPa%, where PSE is increased by 27% compared with the sample after long‐time bainitic austempering.

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Section: Microstructural Evolution During Austempering and Temperingmentioning

confidence: 99%

Comparison of Microstructure and Mechanical Properties of a High‐Carbon Bainitic Steel Treated by Long‐Time Bainitic Austempering and Short‐Time Austempering Plus Tempering Processes

Wang,

Gao,

Gui

et al. 2024

steel research int.

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Some Considerations on Austenite Grain Growth Kinetics from High‐Temperature Laser Scanning Confocal Microscopy Observations

Bernhard,

Kern,

Bernhard

2023

steel research int.

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For more than 20 years, High‐Temperature Laser Scanning Confocal Microscopy (HT‐LSCM) has become worldwide a proven technique for observing various metallurgical phenomena in‐situ. HT‐LSCM turned out to be a reliable and effective method for the observation of quantification austenite grain growth kinetics in steel, being highly relevant in casting and steel processing. The present paper briefly introduces the measurement technique followed by some basics on austenite grain growth. Finally, selected examples of recent research activities are discussed, including investigations in pure iron and the systems Fe‐P, Fe‐C, Fe‐Al‐N and Fe‐C‐Nb‐N. The influence of P on the grain growth kinetics is remarkable. At 1350 °C, the final grain size decreases from 255 µm in pure iron to 145 µm by adding 0.044 wt.‐% P. On the other hand, C enhances the grain growth in specific alloying ranges (0 – 0.30 wt.‐%C), particularly at elevated temperatures. For a typical Al‐content of 0.025 wt.‐% and only 50 wt.‐ppm N, AlN loses the pinning effect above 1150 °C. In case of Nb(C,N), an elevated Nb‐content (0.085 wt.‐%) provides stabilization of Nb(C,N) at 1150 °C, but at 1250 °C, no pinning of Nb(C,N) is visible anymore.This article is protected by copyright. All rights reserved.

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Recent research progress on the phase-field model of microstructural evolution during metal solidification

Wang,

Lv,

et al. 2023

Int J Miner Metall Mater

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Kinetics of austenite growth and bainite transformation during reheating and cooling treatments of high strength microalloyed steel produced by sub-rapid solidification

Cited by 8 publications

References 50 publications

Comparison of Microstructure and Mechanical Properties of a High‐Carbon Bainitic Steel Treated by Long‐Time Bainitic Austempering and Short‐Time Austempering Plus Tempering Processes

Comparison of Microstructure and Mechanical Properties of a High‐Carbon Bainitic Steel Treated by Long‐Time Bainitic Austempering and Short‐Time Austempering Plus Tempering Processes

Some Considerations on Austenite Grain Growth Kinetics from High‐Temperature Laser Scanning Confocal Microscopy Observations

Recent research progress on the phase-field model of microstructural evolution during metal solidification

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