Effect of Alloying Elements on Microstructure and Mechanical Properties of Air-Cooled Bainitic Steel

Shah, Minal; Das, Suchandan K; Chowdhury, Sandip Ghosh

doi:10.1007/s11661-019-05177-1

Cited by 13 publications

(13 citation statements)

References 33 publications

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“…This explains why no bainitic or ferritic transformations occurred during heat treatment. Even the change in temperature, which influences the driving force, did not bring any changes [21]. Lowering the temperature increases the driving force for gamma/alpha transformation.…”

Section: Discussionmentioning

confidence: 88%

Dilatometric Study of Phase Transformations in 5 Mn Steel Subjected to Different Heat Treatments

et al. 2020

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The work presents results of phase transformation kinetics of hot-rolled 5% Mn steel subjected to different heat treatments. Three different schedules were introduced: isothermal holding in a bainite region, coiling simulation and intercritical annealing. The evolution of microstructure components was investigated using dilatometric and metallographic analyses. According to obtained results, the medium-Mn steel exhibits high resistance for γ/α transformation during the bainite transformation and coiling simulation (upon cooling from the austenite region). During 5 h isothermal holding, no bainite and/or ferrite formation was detected. This results in the formation of martensite upon cooling to room temperature. Differently, when the steel was subjected to the intercritical annealing at 720 and 700 °C (upon heating from room temperature), a final microstructure consisted of ferrite, martensite and retained austenite. At 700 °C, no fresh martensite formation was detected upon cooling to room temperature. This means that the austenite was enriched in carbon during the intercritical annealing step enough to keep its thermal stability.

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Section: Discussionmentioning

confidence: 88%

Dilatometric Study of Phase Transformations in 5 Mn Steel Subjected to Different Heat Treatments

et al. 2020

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“…Some serration behavior in Fig. 4b indicates a step-like character of the bainitic transformation with presumable precipitation of carbides in bainite [17]. It means that the continuous cooling is not effective in producing carbide-free bainite.…”

Section: Dilatometric Studymentioning

confidence: 97%

“…Al is one of two elements (the second one is Co) shifting these critical temperatures. However, because manganese is an austenite stabilizer, its higher amount decreases A e1 temperature corresponding to the beginning of cementite precipitation [16,17]. The A e1 temperature is ~ 700 °C for the steel containing 0.17% C. Manganese affects also the start temperatures for martensite and bainite transformations [18].…”

Section: Thermodynamic Calculationsmentioning

confidence: 99%

Dilatometric study of the phase transformations under conditions of recrystallized and non-recrystallized austenite in 3Mn–1.5Al steel

Morawiec

Grajcar

Kozłowska

et al. 2020

J Therm Anal Calorim

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This work presents the results of prior austenite state on the phase transformation behavior in a medium manganese steel alloyed with Al. The austenite was plastically deformed at two different temperatures. The first was at 1050 °C to ensure its recrystallization before cooling. The second treatment included deformation at 900 °C to keep high dislocation density in the austenite. The analysis of recrystallization process or its lack on the phase transformation behavior was analyzed. The study included thermodynamic calculations to analyze proper conditions of selected heat treatments. The dilatometric analysis of the phase transitions dependence on deformation temperatures was carried out. Deformation continuous cooling transformation diagrams were formed on this basis. The metallographic investigations were performed to determine microstructure constituents after cooling. The investigation proved the presence of ferrite untransformed during the austenitization step at 1100 °C. The dominant phase was bainite which was kept present up to 100 °C s−1 cooling rate. The amount of martensite increased with increasing the cooling rate. For the non-recrystallized austenite, more bainite was present in the microstructure for higher cooling rates compared to the recrystallized one. This was the result of higher density of preferable places for bainite nucleation in the non-recrystallized austenite. The Vickers hardness measurements were conducted after the applied heat treatments. The hardness of steel increased together with applying the higher cooling rates, which corresponded to the higher martensite amount. These values were higher for the non-recrystallized austenite because of higher dislocation density.

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Section: Introductionmentioning

confidence: 99%

“…Si was added to promote carbon partitioning in the retained austenite to make it more stable [14][15][16][17]. Mn reduces the bainitic transformation temperature by significantly reducing the ΔG γ→α , explored by Shah et al [16]. Furthermore, the addition of Mo effectively suppresses the ferrite transformation and decreases the transformation temperature of bainite, which helps to obtain ultrafine carbide-free bainite [17][18][19][20][21].…”

Section: Introductionmentioning

confidence: 99%

Dynamic continuous cooling transformation, microstructure and mechanical properties of medium-carbon carbide-free bainitic steel

Chen

Wang

2020

High Temperature Materials and Processes

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The effects of the cooling rate after hot deformation on phase transformation, the microstructure of the designed nonquenched and tempered medium-carbon carbide-free bainitic steel have been investigated during the dynamic continuous cooling process. The results show that with the increase of the cooling rate, the morphology of the carbide-free bainite of the experimental steel evolves from granular bainite to lath bainite. Meanwhile, the hardness increases, and the amount of the retained austenite decreases with the increase of the cooling rate. Besides, the morphology evolution of the retained austenite from block to film is revealed by EBSD. Moreover, 0.5°C/s is considered to be the favorable cooling rate to obtain the best strength–toughness matching. Furthermore, the semi-industrial experimental results proved that the tensile strength, yield strength and Charpy impact energy were 1,298 MPa, 847 MPa and 38 J, respectively.

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Effect of Alloying Elements on Microstructure and Mechanical Properties of Air-Cooled Bainitic Steel

Cited by 13 publications

References 33 publications

Dilatometric Study of Phase Transformations in 5 Mn Steel Subjected to Different Heat Treatments

Dilatometric Study of Phase Transformations in 5 Mn Steel Subjected to Different Heat Treatments

Dilatometric study of the phase transformations under conditions of recrystallized and non-recrystallized austenite in 3Mn–1.5Al steel

Dynamic continuous cooling transformation, microstructure and mechanical properties of medium-carbon carbide-free bainitic steel

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