Effect of Ultrafast Heating on the Properties of the Microconstituents in a Low-Carbon Steel

Valdes-Tabernero, M.A.; Vercruysse, Florian; Sabirov, I.; Petrov, Roumen; Monclús, M.A.; Molina-Aldareguia, J.M.

doi:10.1007/s11661-018-4658-4

Cited by 14 publications

(13 citation statements)

References 14 publications

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“…From these calculations it is seen that the fraction of martensite in the UFH sample was somewhat higher than that in the CH sample. This result is in contradiction with the previous research [9,13,40,41] where it was supported that the increase of the heating rate leads to an increase in the Ac1 temperature and thus, less martensite is expected in the microstructure of the UFH sample than in the CH sample. Though, the difference can be explained by the lack of recrystallization of ferrite in the UFH sample.…”

Section: Texture and Recrystallization Analysiscontrasting

confidence: 98%

The Effect of Ultra-Fast Heating on the Microstructure, Grain Size and Texture Evolution of a Commercial Low-C, Medium-Mn DP Steel

Banis

Durán

Bliznuk

et al. 2019

Metals

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The effect of ultra-fast heating on the microstructures of steel has been thoroughly studied over the last year as it imposes a suitable alternative for the production of ultra high strength steel grades. Rapid reheating followed by quenching leads to fine-grained mixed microstructures. This way the desirable strength/ductility ratio can be achieved while the use of costly alloying elements is significantly reduced. The current work focuses on the effect of ultra-fast heating on commercial dual phase grades for use in the automotive industry. Here, a cold-rolled, low-carbon, medium-manganese steel was treated with a rapid heating rate of 780 °C/s to an intercritical peak temperature (760 °C), followed by subsequent quenching. For comparison, a conventionally heated sample was studied with a heating rate of 10 °C/s. The initial microstructure of both sets of samples consisted of ferrite, pearlite and martensite. It is found that the very short heating time impedes the dissolution of cementite and leads to an interface-controlled α → γ transformation. The undissolved cementite affects the grain size of the parent austenite grains and of the microstructural constituents after quenching. The final microstructure consists of ferrite and martensite in a 4/1 ratio, undissolved cementite and traces of austenite while the presence of bainite is possible. Finally, it is shown that the texture is not strongly affected during ultra-fast heating, and the recovery and recrystallization of ferrite are taking place simultaneously with the α → γ transformation.

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Section: Texture and Recrystallization Analysiscontrasting

confidence: 98%

The Effect of Ultra-Fast Heating on the Microstructure, Grain Size and Texture Evolution of a Commercial Low-C, Medium-Mn DP Steel

Banis

Durán

Bliznuk

et al. 2019

Metals

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“…In the second step, recrystallized and non-recrystallized ferritic grains are separated using the grain orientation spread criterion: Grains with orientation spread below 1º are defined as the recrystallized grains, while grains with an orientation spread above 1º are defined as the non-recrystallized ones [22]. It should be noted that another grain average misorientation based criterion was employed in our recent report [14] for separation of recrystallized/non-recrystallized grains.…”

Section: Microstructural Characterizationmentioning

confidence: 99%

“…Increasing heating rate shifts the recrystallization temperature to higher values than the one measured at conventional heating rates of 10-20°C/s. Recovery and recrystallization processes concurrently occur during ultrafast heating, and increasing the heating rate decreases the recrystallized fraction of ferrite for a given temperature [5][6][7][12][13][14]. The martensite volume fraction in the heat treated steel tends to increase with increasing peak temperature [15].…”

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confidence: 99%

The effect of heating rate and soaking time on microstructure of an advanced high strength steel

Valdes-Tabernero

Celada-Casero

Sabirov

et al. 2019

Materials Characterization

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This work focuses on the effect of soaking time on the microstructure during ultrafast heat treatment of a 50% cold rolled low carbon steel with initial ferritic-pearlitic microstructure.Dilatometry analysis was used to estimate the effect of heating rate on the phase transformation temperatures and to select an appropriate inter-critical temperature for final heat treatments. A thorough qualitative and quantitative microstructural characterization of the heat treated samples is performed using a wide range of characterization techniques. A complex multiphase, hierarchical microstructure consisting of ferritic matrix with embedded martensite and retained austenite is formed after all applied heat treatments. In turn, the ferritic matrix contains recrystallized and non-recrystallized grains. It is demonstrated that the ultrafast heating generally results in finer microstructure compared to the conventional heating independently on the soaking time. There is a significant effect of the soaking time on the volume fraction of martensite of the ultrafast heated material, while in the samples heated with conventional heating rate it remains relatively unchanged during soaking.Recrystallization, recovery and phase transformations occurring during soaking are discussed with respect to the applied heating rate.

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“…In addition, De Knijf et al [21], and Cerda et al, [22] studied the effect of ultrafast heating on recrystallization, showing that nucleation of recrystallized ferrite grains is enhanced by increasing the heating rate and results in refined microstructures. Other studies of Cerda, Papaefthymiou and Petrov et al [20,23] focus on the effect of heating rates and the phase volume fraction and properties of the micro constituents of the initial microstructure. Even though the effect of rapid heating on phase transformations has been studied, the conditions that favor the simultaneous formation of bainite and martensite during quenching from parent austenite with variable carbon content is not well understood.…”

Section: Introductionmentioning

confidence: 99%

Study of Carbide Dissolution and Austenite Formation during Ultra-Fast Heating in Medium Carbon Chromium Molybdenum Steel

Papaefthymiou

Bouzouni

Petrov

2018

Metals

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Abstract:In this study, UltraFast Heat Treatment (UFHT) was applied to a soft annealed medium carbon chromium molybdenum steel. The specimens were rapidly heated and subsequently quenched in a dilatometer. The resulting microstructure consists of chromium-enriched cementite and chromium carbides (in sizes between 5-500 nm) within fine (nano-sized) martensitic and bainitic laths. The dissolution of carbides in austenite (γ) during ferrite to austenite phase transformation in conditions of rapid heating were simulated with DICTRA. The results indicate that fine (5 nm) and coarse (200 nm) carbides dissolve only partially, even at peak (austenitization) temperature. Alloying elements, especially chromium (Cr), segregate at austenite/carbide interfaces, retarding the dissolution of carbides and subsequently austenite formation. The sluggish movement of the austenite/carbide interface towards austenite during carbide dissolution was attributed to the partitioning of Cr nearby the interface. Moreover, the undissolved carbides prevent austenite grain growth at peak temperature, resulting in a fine-grained microstructure. Finally, the simulation results suggest that ultrafast heating creates conditions that lead to chemical heterogeneity in austenite and may lead to an extremely refined microstructure consisting of martensite and bainite laths and partially dissolved carbides during quenching.

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Effect of Ultrafast Heating on the Properties of the Microconstituents in a Low-Carbon Steel

Cited by 14 publications

References 14 publications

The Effect of Ultra-Fast Heating on the Microstructure, Grain Size and Texture Evolution of a Commercial Low-C, Medium-Mn DP Steel

The Effect of Ultra-Fast Heating on the Microstructure, Grain Size and Texture Evolution of a Commercial Low-C, Medium-Mn DP Steel

The effect of heating rate and soaking time on microstructure of an advanced high strength steel

Study of Carbide Dissolution and Austenite Formation during Ultra-Fast Heating in Medium Carbon Chromium Molybdenum Steel

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