Precipitation and grain growth modelling in Ti-Nb microalloyed steels

Graux, Alexis; Cazottes, Sophie; Castro, David; Martín, David San; Capdevila, Carlos; Cabrera, J.M.; Molas, Sílvia; Schreiber, Sebastian J.; Mirković, Djordje; Danoix, F.; Bugnet, Matthieu; Fabrègue, Damien; Perez, Michel

doi:10.1016/j.mtla.2019.100233

Cited by 52 publications

(33 citation statements)

References 39 publications

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“…(Ti,Nb)C precipitates are made responsible for pinning austenite grain boundaries. Due to the thermodynamic calculations presented in [31], it can be concluded that the (Ti,Nb)C precipitates are present at 1000 °C and 1100°C and dissolve at 1200 °C and higher temperatures. The microstructures are analyzed by means of software Fiji [48].…”

Section: Pinning Of Microstructural Entitiesmentioning

confidence: 99%

“…This must be seen under the precondition that the grain boundary arrangement is kept at the same conditions for the whole process. Recently, Graux et al [31] published optical micrographs of steel soaked at 1000 °C, 1100 °C and 1200 °C. While the austenite grains at 1000 °C and 1200 °C seem to be unimodally distributed, the grains at 1100 °C exhibit a deviation from the unimodal distribution.…”

Section: Pinning Of Microstructural Entitiesmentioning

confidence: 99%

“…The particles (e.g., NbC or (Ti,Nb)C) pin the grains at the low soaking temperature, however at a high temperature the particles dissolve resulting in a subsequent unpinning of grains. Experimental evidence of these features of the microstructural evolution in microalloyed steels can be found in [29][30][31].…”

Section: Introductionmentioning

confidence: 99%

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Influence of Finite Mobilities of Triple Junctions on the Grain Morphology and Kinetics of Grain Growth

Gamsjäger

Gschöpf

Svoboda

2020

Metals

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Grain boundary networks composed of equal microstructural elements were investigated in a recent paper. In this work a more complicated artificial grain topology consisting of one four-sided, two six-sided and one eight-sided grain is designed to further investigate the influence of grain boundary and triple junction mobilities on the kinetics of the system in more detail. Depending on the value of the equal mobility of all triple junctions, the initially square-shaped four-sided grain changes its shape to become more or less rectangular. This indicates that the grain morphology is influenced by the value of the mobility of the triple junctions. It is also demonstrated that a grain arrangement with low mobility triple junctions controlling the kinetics of grain growth enhances growth of the large eight-sided grains. In addition, grain growth is investigated for different values of mobilities of triple junctions and grain boundaries. A strong elongation of several grains is predicted by the modeling results for reduced mobilities of the microstructural grain boundary elements. The two-dimensional modeling results are compared to micrographs of a heat-treated titanium niobium microalloyed steel. This feature, namely the evolution of elongated grains, is observed in the micrograph due to the pinning effect of (Ti, Nb)C precipitates at elevated soaking temperatures of around 1100 °C. Furthermore, the experiments show that a broader distribution of the grain sizes occur at 1100 °C compared to soaking temperatures, where pinning due to precipitates plays a less prominent role. A widening of the distribution of the grain sizes for small triple junction mobilities is also predicted by the unit cell model.

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Section: Pinning Of Microstructural Entitiesmentioning

confidence: 99%

Section: Pinning Of Microstructural Entitiesmentioning

confidence: 99%

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Influence of Finite Mobilities of Triple Junctions on the Grain Morphology and Kinetics of Grain Growth

Gamsjäger

Gschöpf

Svoboda

2020

Metals

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“…With (8) and (9) kept in mind, equation: D J Yet, it is difficult to make use of Eq. (10) since even in case of the single type of the barrier particles accurate determination of their dimensions and volume fraction [17] is rarely possible. That is why, to allow for Zener's pressure in empirical models, a virtually ultimate grain size D lim is introduced:…”

Section: Model Descriptionmentioning

confidence: 99%

“…The normal grain growth exerts a notable effect on the austenite microstructure during hot rolling and strongly influences the microstructures of the heat affected zone in weld joints of steels. Owing to the practical significance of this phenomenon, it has attracted attention in many original works [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] and in monographs [18,19]. Grain growth is conventionally expressed [1][2][3][4][5][6][7] by the equation:…”

Section: Introductionmentioning

confidence: 99%

Modeling of grain growth kinetics in complexly alloyed austenite

Vasilyev

Sokolov

et al. 2019

Lett. Mater.

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A quantitative model is presented to describe the kinetics of grain growth in complexly alloyed austenite. The model assumes that the activation energy of grain growth is proportional to the activation energy of bulk self-diffusion, which is calculated as a function of the chemical composition of the solid solution using the previously obtained formula. The empirical parameters of the model are determined on the basis of experimental data on the kinetics of isothermal grain growth in steels with the chemical composition varying in a wide range: C (0.05 ÷ 0.32), Mn (0.30 ÷1.88), Si (0.01÷ 0.29), Ni (0.0 ÷ 4.0), Cr (0.0 ÷ 2.0), Mo (0.0 ÷ 0.5), Nb (0.00 ÷ 0.05) available in the literature. The model allows one to obtain good agreement with the experiment for the considered steels in which the minimum (~ 79.7 kJ / mol) and maximum (~ 243.7 kJ / mol) values of the activation energy of grain growth differ by 3 times. The average absolute value of the relative error in calculating the grain size is about 11 % that is comparable to the measurement error. Taking into account the influence of the chemical composition on the activation energy of grain growth, implemented in the developed model, it is possible to obtain agreement with the experiment without accounting for the solid-solution pinning of moving boundaries (the solute drag effect) requires a large number of additional empirical parameters (two exponential parameters for each alloying element). This result deserves further consideration from the physical viewpoint and verification on both simple carbon steels and steels with various quantities of Mn, Mo and Nb, which, according to literature, exert the strongest solute drag effect.

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Post‐fire Mechanical Behaviors and the Mechanism of their Influence on a 690 MPa Grade High‐Strength Steel for High‐Rise Buildings

Zhu

Cui

Yan

et al. 2022

steel research int.

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Herein, the residual mechanical behaviors of a 690 MPa grade high‐strength steel after exposure to fire for an extended duration are investigated, and the factors affecting their variation based on the theories of metallurgy are explored. The corresponding tensile properties and microstructure tests are conducted on this steel soaked at 300–900 °C for 3 h and then cooled in air. The results show that there is negligible influence of temperature on residual mechanical properties at 600 °C or lower. It can be considered that the critical fire temperature is 600 °C, beyond which the strength decreases sharply. This can be attributed to the formation of ferrite and grain coarsening. However, at 900 °C, its residual strength can still maintain approximately half of that at room temperature. It is related to the contribution from fine nanoscaled precipitates of 10–40 nm in size. Compared with steels having the same nominal yield strength, the dependence of residual mechanical properties on elevated temperatures for this steel varies due to the difference in microstructure characteristics. New predicted equations are proposed for this novel structural steel to guide on better prediction of residual mechanical properties in steel structure systems.

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Precipitation and grain growth modelling in Ti-Nb microalloyed steels

Cited by 52 publications

References 39 publications

Influence of Finite Mobilities of Triple Junctions on the Grain Morphology and Kinetics of Grain Growth

Influence of Finite Mobilities of Triple Junctions on the Grain Morphology and Kinetics of Grain Growth

Modeling of grain growth kinetics in complexly alloyed austenite

Post‐fire Mechanical Behaviors and the Mechanism of their Influence on a 690 MPa Grade High‐Strength Steel for High‐Rise Buildings

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