Effect of the bainitic transformation temperature on retained austenite fraction and stability in Ti microalloyed TRIP steels

Kammouni, Abdelkhalek; Saikaly, W.; Dumont, M.; Marteau, C.; Bano, X.; Charaı̈, A.

doi:10.1016/j.msea.2009.05.015

Cited by 54 publications

(34 citation statements)

References 17 publications

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“…There are quite a few numbers of identified factors that play a conclusive role, such as chemical composition, primary austenite grain size and morphology and distribution of microstructural constituents 5,[22][23][24][25][26][27][28][29][30] . This article aims to investigate and characterize some of the most exceptional and unique microstructural features obtained in two nanostructured bainitic steels with different amounts of Ni, Mn and V to study how they contribute to respective final mechanical response in more detail.…”

Section: Introductionmentioning

confidence: 99%

Characterisation of microstructure and mechanical properties in two different nanostructured bainitic steels

Avishan¹,

Yazdani²,

Caballero³

et al. 2015

Materials Science and Technology

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Recently, valuable combinations of mechanical properties with strength of 1.9 GPa accompanied by very decent ductility of 19 % and toughness of 31 J, have been achieved in a set of nanostructured bainitic steels. However, it is necessary to elucidate the significance of various microstructural features responsible of that extraordinary mechanical response in more detail.Thus, using two steels, with different Mn, Ni and V contents, and changing the nanostructured bainite isothermal transformation temperatures (200-300 ºC), has led to a plethora of subtle and essential microstructural variations, necessary to explain how the mechanical response of nanostructured bainite is attained.

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Section: Introductionmentioning

confidence: 99%

Characterisation of microstructure and mechanical properties in two different nanostructured bainitic steels

Avishan¹,

Yazdani²,

Caballero³

et al. 2015

Materials Science and Technology

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“…Xiong et al [11] reported that martensite transformation takes place in high carbon blocky RA at the onset of deformation, while low carbon film-like RA, despite having much lower carbon content, is stable at strains up to 12%. In addition, Kammouni et al [12] investigated the effect of bainite transformation temperature on RA fraction and stability in microalloyed TRIP steels. It was found that this temperature affects the size and morphology of the RA which play important roles on its stability.…”

Section: Introductionmentioning

confidence: 99%

Effect of ausforming on the stability of retained austenite in a C-Mn-Si bainitic steel

Wang

et al. 2015

Met. Mater. Int.

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The effect of ausforming on the stability of retained austenite in a C-Mn-Si bainitic steel was investigated through metallography, X-ray diffraction and dilatometry. The geometrical relationships of the amount of bainite transformation and the volume fractions of retained austenite with deformation strains were studied. The results show that the degree of promotion of small strains on bainite transformation is nonlinear because of the dual effects of accelerated nucleation and retarded growth caused by ausforming. The transformed bainite fraction first increased and then decreased with increased small strains. It indicates that there is a maximum degree of the promotional function corresponding to a certain small strain at low temperature. Although small strains promote bainite transformation, a larger quantity of retained austenite exists at room temperature due to the suppressed martensite transformation during the cooling process after bainite transformation. The carbon content in retained austenite increases with the amount of baintie transformation, which contributes to the stability of austenite. Compared with the stabilizing effect due to carbon enrichment, mechanical stabilization caused by ausforming has a decisive effect on determining the volume fraction of retained austenite after isothermal bainite transformation.

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“…When the hardenability is increased by carbon enrichment of austenite is possible to use slow cooling rates to achieve a martensitic microstructure, avoiding the formation of ferrite, pearlite and bainite from remaining austenite decomposition 22,24 . However, some retained austenite may be present in microstructure after the final cooling 25,26 .…”

Section: Formation Of Microphases and Constituents From Remaining Ausmentioning

confidence: 99%

“…It is well known that the local carbon enrichment can play an important role in the transformation temperature 4,[10][11][12][13][14][15][16][17][18][19][20][21][22]26 , for example, the reduction of the carbon content in the remaining austenite increases Ms temperature. Also, the high cooling rates displace the Ar 3 temperature of steel, decreasing its value and favoring the partial or total transformation of bainite and martensite.…”

Section: Formation Of Microphases and Constituents From Remaining Ausmentioning

confidence: 99%

Formation of Microphases and Constituents from Remaining Austenite Decomposition in API X80 Steel Under Different Processing Conditions

et al. 2015

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The main goal this work is to evaluate the occurrence of the constituents and microphases observed in as-received API X80 pipe through the microstructures transformed from rich-carbon remaining austenite obtained via heat treatments. These heat treatments comprised austenitization at 1000 °C for 30 minutes, followed by annealing at 700 °C, 623 °C, 542 °C and 462 °C for 15, 60 and 300 minutes and then cooling in water or still air. The effects of the increase in annealing parameters were: 1) the increase of microhardness values of the MA constituents and martensite islands, 2) the grain size of both ferritic phase and the martensite islands were increased, 3) the rise in the mean free path of ferrite and 4) the microstrains of samples were decreased. The cooling rates influenced significantly the transformation of carbon-rich remaining austenite to hard constituents and several microphases. After annealing at 700 °C during 60 min followed by quenching, the morphology of the MA constituents and its microhardness values were compatible for both heat-treated and as-received conditions.

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Effect of the bainitic transformation temperature on retained austenite fraction and stability in Ti microalloyed TRIP steels

Cited by 54 publications

References 17 publications

Characterisation of microstructure and mechanical properties in two different nanostructured bainitic steels

Characterisation of microstructure and mechanical properties in two different nanostructured bainitic steels

Effect of ausforming on the stability of retained austenite in a C-Mn-Si bainitic steel

Formation of Microphases and Constituents from Remaining Austenite Decomposition in API X80 Steel Under Different Processing Conditions

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