Super-Bainite

Caballero, Francisca G.; García‐Mateo, C.

doi:10.1016/b978-0-12-819726-4.00034-x

Cited by 5 publications

(7 citation statements)

References 82 publications

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“…Carbide-free bainitic steel has been the subject of considerable attention in recent years because of its effective combination of strength, ductility, and toughness [1][2][3][4][5]. The microstructure of carbide-free bainitic steel typically consists of nano-sized bainitic ferrite plates and austenite films [6,7]. The thickness of bainitic ferrite plates is influenced by chemical composition and transformation temperature [8][9][10].…”

Section: Introductionmentioning

confidence: 99%

“…The thickness of bainitic ferrite plates is influenced by chemical composition and transformation temperature [8][9][10]. Generally, as the transformation temperature decreases from the bainite start temperature (Bs) to 10 • C above the martensite start temperature (Ms), or the carbon content of bainitic steel increases from low carbon (0.2-0.4 wt.%) to high carbon (0.7-0.9 wt.%), the bainitic plates become finer [6,7,9,10]. Since the grain refinement of bainitic ferrite and the transformation-induced plasticity of the retained austenite contribute to enhanced strength and toughness, bainitic steel exhibits superior mechanical properties [11,12].…”

Section: Introductionmentioning

confidence: 99%

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Experimental and Modelling Research on the Effect of Prior Ferrite on Bainitic Transformation in Medium-Carbon Bainitic Steel

Yu,

Liu,

et al. 2024

Crystals

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In this study, we investigate the impact of prior ferrite on the bainite transformation kinetics and microstructure of medium-carbon steel interrupted by an intercritical annealing (IAA) process. It was found that the incubation time and completion time decreased from 687 s and 6018 s to 20 s and 4680 s, with the volume fraction of ferrite increasing from 9.5% to 28.6%, while the maximum transformation rate increased from 00271 μm/s to 0.0436 μm/s. The ferrite/austenite interface is introduced, and the nucleation sites are increased to accelerate the subsequent bainite transformation due to the formation of prior ferrite. However, there is a competitive relationship between the number and activation energy of bainite nucleation. According to the experimental results and theoretical calculations, the activation energy of the bainite transformation in the medium-carbon bainite steel decreases gradually with an increase in the volume fraction of prior ferrite.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Experimental and Modelling Research on the Effect of Prior Ferrite on Bainitic Transformation in Medium-Carbon Bainitic Steel

Yu,

Liu,

et al. 2024

Crystals

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“…Ultra-fine bainite steel, also known as super bainite steel, nano-bainite steel and lowtemperature bainite steel, has become a research hotspot due to its excellent combination of strength and ductility [1][2][3]. Ultra-fine bainitic ferrite plates, 20 nm~1 µm in thickness, within high dislocation densities provide the steel with high strength, and the film-like retained austenite embedded into the plates can absorb microcrack propagation, thereby ensuring its high toughness property [4][5][6].…”

Section: Introductionmentioning

confidence: 99%

Ultra-Fine Bainite in Medium-Carbon High-Silicon Bainitic Steel

Yu,

Wang,

et al. 2024

Materials

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The effects of austenitizing and austempering temperatures on the bainite transformation kinetics and the microstructural and mechanical properties of a medium-carbon high-silicon ultra-fine bainitic steel were investigated via dilatometric measurements, microstructural characterization and mechanical tests. It is demonstrated that the optimum austenitizing temperature exists for 0.3 wt.%C ultra-fine bainitic steel. Although the finer austenite grain at 950 °C provides more bainite nuclei site and form finer bainitic ferrite plates, the lower dislocation density in plates and the higher volume fraction of the retained austenite reduces the strength and impact toughness of ultra-fine steel. When the austenitizing temperature exceeds 1000 °C, the true thickness of bainitic ferrite plates and the volume fraction of blocky retained austenite in the bainite microstructure increase significantly with the increases in austenitizing temperature, which do harm to the plasticity and impact toughness. The effect of austempering temperature on the transformation behavior and microstructural morphology of ultra-fine bainite is greater than that of austenitizing temperature. The prior martensite, formed when the austempering temperature below Ms, can refine the bainitic ferrite plates and improve the strength and impact toughness. However, the presence of prior martensite divides the untransformed austenite and inhibits the growth of bainite sheaves, thus prolonging the finishing time of bainite transformation. In addition, prior martensite also strengthens the stability of untransformed austenite though carbon partition and enhances the volume fraction of blocky retained austenite, which reduces the plasticity of ultra-fine bainitic steel. According to the experimental results, the optimum austempering process for 0.3 wt. %C ultra-fine bainitic steel is through austenitization at 1000 °C and austempering at 340 °C.

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“…Ultrafine-grained multiphase steels with a microstructure composed of carbide-free bainitic ferrite laths and retained austenite have received recently much attention due to their superior mechanical properties. These steels have the application potential in the automotive industry, machine industry and others, where high strength in combination with good plasticity and high toughness are needed [1][2][3]. The thickness of bainite laths depends on the chemical composition of steel and heat treatment parameters.…”

Section: Introductionmentioning

confidence: 99%

Effect of prior martensite formation on the bainite transformation kinetics in high-strength 3% Mn multiphase steel

Morawiec

Skowronek

Kozłowska

et al. 2022

J Therm Anal Calorim

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The work presents results on the effect of prior martensite formation on bainite transformation kinetics in a 3% medium-Mn multiphase steel. The material was subjected to two isothermal holding temperatures: 400 °C (without martensite) and 350 °C (with prior martensite). According to obtained dilatometric results, the formation of prior martensite leads to the acceleration of bainite transformation kinetics. The bainite formation starts and finishes much faster, when the prior martensite was present before the isothermal holding. The microstructural investigation of the steel after heat treatment was carried out using light and scanning electron microscopy. The microstructures were composed of fine bainitic laths with retained austenite and small amount of martensitic-austenitic islands at 400 °C. At 350 °C the presence of large tempered martensite laths was detected. The bainite is composed of a mixture of fine and coarse laths. The increase of the bainitic lath thickness is attributed to the coalescence process occurring at the lower holding temperature. The differences in the steel hardness after the two heat treatments were relatively small (~ 13 HV10).

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Super-Bainite

Cited by 5 publications

References 82 publications

Experimental and Modelling Research on the Effect of Prior Ferrite on Bainitic Transformation in Medium-Carbon Bainitic Steel

Experimental and Modelling Research on the Effect of Prior Ferrite on Bainitic Transformation in Medium-Carbon Bainitic Steel

Ultra-Fine Bainite in Medium-Carbon High-Silicon Bainitic Steel

Effect of prior martensite formation on the bainite transformation kinetics in high-strength 3% Mn multiphase steel

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