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

Morawiec, Mateusz; Grajcar, A.; Zalecki, W.; García‐Mateo, C.; Opiela, M.

doi:10.3390/ma13040958

Cited by 15 publications

(15 citation statements)

References 22 publications

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“…The development of advanced ultrahigh strength steels is promoted by the need for lightweight bodies, and medium-Mn steels with 3–10% Mn are considered one of the most promising materials for automobile mass reduction [ 1 , 2 , 3 ]. When medium-Mn steels were first developed by Miller in 1972 [ 4 ], a substantial amount of research and development work had been carried out.…”

Section: Introductionmentioning

confidence: 99%

Strong Interactions between Austenite and the Matrix of Medium-Mn Steel during Intercritical Annealing

et al. 2020

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The effects of heat treatment on the microstructure evolution was studied in regards to austenite nucleation and grain growth. It was found that the austenite nucleation and matrix recrystallization kinetics of samples annealed at 675 °C for different times were revealed, implying a strong interaction between the ferrite matrix and austenite was revealed. The recrystallization of the matrix during annealing provided favorable conditions for austenite nucleation and growth, and the formation of austenite during this process reduced the matrix recrystallization kinetics, thus delaying the recrystallization process of the matrix around the austenite grains. The statistical results for the austenite grain size under different annealing temperatures indicated that the average grain size of the austenite slightly increases with increasing of the annealing temperature, but the austenite with the largest grain size grows faster at the same temperature. This difference is attributed to the strict Kurdjumov Sachs (KS) orientation relationship (OR) between the austenite grains and the matrix, because the growth of austenite with a strict KS OR with the matrix is often inhibited during annealing. In contrast, the austenite maintains a non-strict KS OR with the matrix and can grow preferentially with increasing annealing temperature and time.

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Section: Introductionmentioning

confidence: 99%

Strong Interactions between Austenite and the Matrix of Medium-Mn Steel during Intercritical Annealing

et al. 2020

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“…These changes correspond to phase transformations, which are typically accompanied by dimension changes of the sample caused by the re-arrangement of the atoms during phase transition. In this way, critical temperatures of the steel, such as Ac1, Ac3 martensite start (Ms) and martensite finish (Mf) temperatures can be determined and even the transformation rate can be established [9]. The knowledge of these temperatures, together with the choice of the suitable cooling rate are necessary factors for the successful design of heat treatment of steels [10][11][12][13][14].…”

Section: Introductionmentioning

confidence: 99%

“…Especially for high strength steels it is necessary to distinguish between martensitic and bainitic transformation, to monitor the volume fraction of all microstructural constituents etc. [9].…”

Section: Introductionmentioning

confidence: 99%

Comparison of high strength steels with different aluminium and manganese contents using dilatometry

Hajšman¹,

Kučerová²,

Burdová³

2020

Manufacturing Technology

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In this paper, the properties of three low carbon steels containing different percentage of manganese (1.5 or 3 wt %) and aluminium (1.5 or 2 wt %) were tested using dilatometric analysis and metallography. The steels had chemical compositions typical for TRIP (Transformation induced plasticity) steels and the two steels with an increased manganese content already belonged to the third generation of AHS (advanced high strength) steels. The dilatometric measurement was employed not only to determine the characteristic transformation temperatures but also to simulate the heat treatment procedure commonly used for TRIP steels. Resulting microstructures obtained through this simulation were evaluated and compared. The two main alloying elements were proved to have a significant effect on the transition temperatures and thus on the processability and overall resulting properties of the material.

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“…Medium-manganese sheet steels containing 3-12 wt% Mn and belonging to the third generation of AHSS (Advanced High Strength Steels) are currently very popular among researchers and industry due to the combination of high strength properties and relatively good plasticity. There are several variants of heat treatment for these steels: intercritical annealing after cold rolling [1] or hot rolling [2], and isothermal holding in a bainitic region [3].The goal of each is to obtain a large fraction of retained austenite in the structure characterized by optimal thermal and mechanical stabilities. To do this, it is necessary to enrich the austenite with stabilizing elements-carbon and manganese-thanks to which the M sγ (martensite start) temperature is reduced and thus there is no martensitic transformation during the steel cooling to room temperature.…”

Section: Introductionmentioning

confidence: 99%

Physical simulation and dilatometric study of double-step heat treatment of medium-Mn steel

Skowronek

Morawiec

Ruiz-Jimenez³

et al. 2020

Archiv.Civ.Mech.Eng

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The work addresses physical simulation and dilatometric study of one-step and double-step heat treatments of medium-Mn steel designed for automotive sheets. The conventional one-step isothermal bainitic transformation was applied as the reference heat treatment. The newly implemented heat treatment consisted of isothermal holding in a bainitic region followed by additional holding of the material at reduced temperature also in the bainitic range. This step was added to refine the microstructure, which led to the stabilization of the retained austenite. Calculations of equilibrium state and non-equilibrium cooling and simulations of the developed thermal cycles were performed using the thermodynamic JMatPro software. The physical simulations of the heat treatment were performed in the dilatometer. The obtained samples were subjected to microscopic observations using light and SEM microscopy. One- and two-step heat treatments allowed to obtain bainitic structures with high contents of retained austenite. Lowering the temperature of one-step isothermal holding resulted in the bainite refinement and adjacent retained austenite. The increased Mn content in steel increased its susceptibility to form coalesced bainite resulting in the partial formation of thicker plates despite a decrease in a process temperature.

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

Cited by 15 publications

References 22 publications

Strong Interactions between Austenite and the Matrix of Medium-Mn Steel during Intercritical Annealing

Strong Interactions between Austenite and the Matrix of Medium-Mn Steel during Intercritical Annealing

Comparison of high strength steels with different aluminium and manganese contents using dilatometry

Physical simulation and dilatometric study of double-step heat treatment of medium-Mn steel

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