Orientation correlation during diffusional α → γ phase transformation in a ferritic low carbon steel

Brückner, G.; Pośpiech, Janusz; Seidl, Ingold; Gottstein, Günter

doi:10.1016/s1359-6462(01)00956-3

Cited by 35 publications

(21 citation statements)

References 12 publications

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“…Texture memory under conventional heating circumstances was already observed by Yoshinaga 18) on a Mn alloyed IF steel. According to Gottstein et al 19) the memory effect can be attributed to the fact that nucleation is restricted to triple junctions of the parent phase matrix.…”

Section: A A-g G-a a Transformationmentioning

confidence: 99%

Grain Refinement and Texture Change in Interstitial Free Steels after Severe Rolling and Ultra-short Annealing

et al. 2003

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A Ti-stabilized interstitial free steel was highly cold deformed to a reduction of 95 % and subsequently submitted to extremely short annealing cycles with heating rates varying between 300°C/s and 4 500°C/s followed by water quench at various temperatures. The microstructural and textural development was studied through various consecutive stages: partially recrystallized, fully recrystallized and after a→g→a transformation. It was found that irrespective of the heating rate the recrystallization has completely terminated before the onset of the ferrite to austenite phase transformation. In the fully recrystallized condition, ultrarapid heating gave rise to substantially refined structures with an average ferrite grain size of 6 mm. It was also observed that this grain refinement saturates with heating rates beyond 1 000°C/s.The transformation structures obtained by ultra fast heating to temperatures in the full austenite region exhibited remarkably coarser grains than the ones observed after ferrite annealing. This coarsening effect was attributed to the effects of heterogeneous nucleation during phase transformation as C was initially present as TiC precipitates in the ferrite matrix.With regard to the texture formation, the characteristic {111} deep drawing fibre of cold rolled IF steels was observed, irrespective of the heating rate, in an annealing treatment as short as 0.3 s. After the forward and reverse a→g transformation, the ensuing ferrite texture displayed a strong memory effect, as the {111} fibre was even more intense after the double transformation than before.

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Section: A A-g G-a a Transformationmentioning

confidence: 99%

Grain Refinement and Texture Change in Interstitial Free Steels after Severe Rolling and Ultra-short Annealing

et al. 2003

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“…Mostly, the Kurdjumov-Sachs and the Nishiyama-Wassermann relationships are used when the orientation relations between FCC and BCC phases are studied. Although there has been a lot of recent research [10][11][12][13][14][15][16][17][18][19] concerning which of these orientation relationships prevails, there is still considerable debate on the relative importance of these orientation relationships because the angular differences between the different orientation relationships is small which makes the experimental verification difficult. Recently, also other orientation relationships 5,6) were taken into account during the study of the crystallographic aspects of the FCC-BCC phase transformation.…”

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confidence: 99%

Evaluation of the Crystallographic Orientation Relationships between FCC and BCC Phases in TRIP Steels

2009

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The crystallographic orientation relationships that are active during the transformation of austenite to bainite are studied for two TRIP steels by means of Electron BackScatter Diffraction (EBSD). A detailed evaluation of about 360 retained austenite grains and their BCC neighbours was performed. Three relationships were considered, namely Kurdjumov-Sachs, Nishiyama-Wassermann and Pitsch. It was found that the majority of the austenite grains had at least one neighbour that could be related with one of the three orientation relationships. The Kurdjumov-Sachs relationship appeared to be dominant and no strong indication for variant selection could be retrieved from the studied data. It was, however, also demonstrated that some precautions need to be made since a clear distinction between the evaluation of a small region of the microstructure and conclusions made for the complete material is necessary.KEY WORDS: TRIP steels; EBSD; phase transformation; crystallographic orientation relationships. 1601© 2009 ISIJ KS variants. The number of variants for the other orientation relationships can be deduced in a similar way. A g-a orientation relationship actually represents a misorientation between two crystallographic orientations. Therefore, this misorientation is most frequently described by means of an axis/angle pair ͗d͘w. Consequently, the last column of Table 1 gives the axis/angle representation with the minimum misorientation angle of the different orientation relationships.The Bain orientation relationship is the simplest orientation relationship, but it is never observed in steels. Therefore, this orientation relationship serves as a first approximation or a reference point when the transformation of austenite into a BCC phase is studied. Mostly, the Kurdjumov-Sachs and the Nishiyama-Wassermann relationships are used when the orientation relations between FCC and BCC phases are studied. Although there has been a lot of recent research [10][11][12][13][14][15][16][17][18][19] concerning which of these orientation relationships prevails, there is still considerable debate on the relative importance of these orientation relationships because the angular differences between the different orientation relationships is small which makes the experimental verification difficult. Recently, also other orientation relationships 5,6) were taken into account during the study of the crystallographic aspects of the FCC-BCC phase transformation. 10,20) An overview of some features of the different rational orientation relations is given in Fig. 2. Figure 2 illustrates how the different variants of the different orientation relationships would appear around one Bain variant on a {100} BCC pole figure. When the three Bain variants are shown on a pole figure, each of them is surrounded by eight KS and four NW variants, respectively. The crystallographic misorientation between two neighbouring KS variants is 10.53°, whilst the misorientation between Bain and a KS variant is 11.06°and the misorientation between Bain and a NW vari...

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“…the a→g and the g→a transformation were obtained and could be evaluated. According to the results of a former study, 24) where the diffusion driven transformation from ferrite to austenite was investigated on a microscopic scale by use of EBSD (electron backscatter diffraction), the crystallographic relationship of the transformation for the material under investigation was unambiguously identified as the Kurdjumov-Sachs (K-S).…”

Section: Methodsmentioning

confidence: 99%

“…During the a→g transformation each single parent grain transforms into several variants of the K-S relation and thus, decomposes its grain into several austenite grains as shown in a former study. 24) Therefore, complementary variants are located next to each other separated by grain boundaries and triple lines. On back transformation these grain boundaries and triple lines become nucleation sites for ferrite.…”

Section: Variant Selection During the G G→ →A A Transformationmentioning

confidence: 99%

Transformation Textures during Diffusional .ALPHA..RAR..GAMMA..RAR..ALPHA. Phase Transformations in Ferritic Steels.

Brückner

Gottstein

2001

ISIJ International

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Orientation correlation during diffusional α → γ phase transformation in a ferritic low carbon steel

Cited by 35 publications

References 12 publications

Grain Refinement and Texture Change in Interstitial Free Steels after Severe Rolling and Ultra-short Annealing

Grain Refinement and Texture Change in Interstitial Free Steels after Severe Rolling and Ultra-short Annealing

Evaluation of the Crystallographic Orientation Relationships between FCC and BCC Phases in TRIP Steels

Transformation Textures during Diffusional .ALPHA..RAR..GAMMA..RAR..ALPHA. Phase Transformations in Ferritic Steels.

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