Transformation Texture in Hot-rolled Steel Sheets and Its Quantitative Prediction

Tomida, Toshiro; Wakita, Masashi

doi:10.2355/isijinternational.52.601

Cited by 18 publications

(16 citation statements)

References 24 publications

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“…It has been recently shown [79][80][81][82] that the strain accommodation may take place across the parent grain boundary by selecting some preferred variants that hold a near K-S OR with the two adjacent  grains. Let us apply this VS criterion to the observed modification of GB axes in the non-deformed and hot-rolled samples.…”

Section: Effect Of Frt On the Variant Selectionmentioning

confidence: 99%

Crystallographic Reconstruction Study of the Effects of Finish Rolling Temperature on the Variant Selection During Bainite Transformation in C-Mn High-Strength Steels

Bernier

Bracke

Malet

et al. 2014

Metall Mater Trans A

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The effect of finish rolling temperature (FRT) on the austenite-(  ) to-bainite ( ) phase transformation is quantitatively investigated in high-strength C-Mn steels. In particular, the present study aims to clarify the respective contributions of the  conditioning during the hot rolling and the variant selection (VS) during the phase transformation to the inherited texture.To this end, an alternative crystallographic  reconstruction procedure, which can be directly applied to experimental electron backscatter diffraction (EBSD) mappings, is developed by combining the best features of the existing models: the orientation relationship (OR) refinement, the local pixel-by-pixel analysis and the nuclei identification and spreading strategy. The applicability of this method is demonstrated on both quenching and partitioning (Q&P) and as-quenched lath-martensite steels. The results obtained on the C-Mn steels confirm that the sample finish rolled at the lowest temperature (829°C) exhibits the sharpest transformation texture. It is shown that this sharp texture is exclusively due to a strong VS from parent brass {110}<1-12>, S {213}<-3-64> and Goss {110}<001> grains, whereas the VS from the copper {112}<-1-11> grains is insensitive to the FRT. In addition, a statistical VS analysis proves that the habit planes of the selected variants do not systematically correspond to the predicted active  slip planes using the Taylor model. In contrast, a correlation between the Bain group to which the selected variants belong and the FRT is clearly revealed, regardless of the parent orientation. These results are discussed in terms of polygranular accommodation mechanisms, especially in view of the observed development in the hot-rolled samples of high-angle grain boundaries with misorientation axes between <111>  and <110>  .

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Section: Effect Of Frt On the Variant Selectionmentioning

confidence: 99%

Crystallographic Reconstruction Study of the Effects of Finish Rolling Temperature on the Variant Selection During Bainite Transformation in C-Mn High-Strength Steels

Bernier

Bracke

Malet

et al. 2014

Metall Mater Trans A

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“…The mechanism of variant selection has been intensively studied on the γ→α phase transformation in the cooling process [1][2][3][4][5][6][7] because the eventual texture after cooling has a signi cant in uence on the various mechanical properties of the nal products. The crystal orientation selection rule during the reverse phase transformation (α→γ) in the heating process is also important for controlling the microstructure in the steel making process.…”

Section: Introductionmentioning

confidence: 99%

“…Tomida et al proposed the variant selection model for α−γ transformation based on the orientation relationship at multiple interfaces with different α grains showing the texture memory effect. They assumed that the orientation of γ during reverse transformation is selected in order to satisfy the Kurdjumov-Sachs (K-S) relationship 23) or near K-S relationship at two or more interfaces with adjacent α grains at the same time 6,7) . They call this hypothetical relationship the double K-S relationship.…”

Section: Introductionmentioning

confidence: 99%

<i>In Situ</i> EBSD Analysis on the Crystal Orientation Relationship between Ferrite and Austenite during Reverse Transformation of an Fe-Mn-C Alloy

et al. 2016

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The crystal orientation of nucleating austenite during reverse phase transformation of a C-Mn steel has been investigated by in situ EBSD technique using a heating stage of FE-SEM at temperatures ranging from RT to 800 C. It has been found that the multiple interfaces between a nucleating austenite grain and the surrounding parent ferrite grains are preferentially selected as the Kurdjumov-Sachs (K-S) relationship. More than 50% of austenite grains are surrounded with two or more parent ferrite grains satisfying the K-S relationship with a deviation within 7 . Based on these ndings, a nucleation model at triple junction is proposed, which supposes that the orientation of nucleating austenite is selected to satisfy the K-S relationship or the orientation relationship close to K-S relationship at two of the interfaces to ferrite grains, and at the other interfaces to minimize the misorientation from the K-S relationship.

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“…[1][2][3][4][5][6][7][8][9][10][11] Moreover, the textural memory phenomena of phase transformation, the K-S orientation relationship and the variant selection phenomena have also been widely observed in various steels, [12][13][14][15][16][17][18][19][20] and the mechanism of their formation is considered to be based on grain boundary nucleation and double K-S (Kurdjumov-Sachs) relationship. [20][21][22][23] However, it is rarely reported how to retain {100} textures in hot rolled sheets. We have observed in previous studies 1) that it is difficult to obtain a strong {100} texture in commercial low grades electrical steel after hot rolling, cold rolling and phase transformation annealing, though the cast slabs exhibit {100} columnar grain.…”

Section: Introductionmentioning

confidence: 99%

Transformation Delay and Texture Memory Effect of Columnar Grained Cast Slab in Low Grades Non-oriented Electrical Steels

Yang

et al. 2021

ISIJ Int.

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The cast slab of low grades non-oriented electrical steels experiences twice diffusional solid phase transformation and demonstrates the features of strong morphological memory referring to columnar structure and texture memory referring to the preferred < 100 > texture at room temperature. In this paper, electron backscatter diffraction (EBSD), quasi-insitu observation of heating samples, and dilatometry are used to study and analyze the two kinds of memory phenomena. The results show that the cast slab consists of about 70% coarse columnar grains and 30% small equiaxed grains. Many small equiaxed grains show Σ3 misorientations with columnar grains indicating K-S orientation relationship obeyed during phase transformation. Coarse columnar grains show a typical < 100 > ||growing axis orientation which is the same as solidified columnar grains. The quasi-insitu observation shows that transformation of columnar grained ferrite to austenite is very sluggish and columnar grained ferrite can still be seen even at a superheating degree of 176°C for 1 hour. Dilatometry measurement indicates that the starting transformation temperatures for a columnar-grain-dominant sample and a small-equiaxed-grain-dominant sample are similar, whereas their transformation extents are quite different with columnar grained sample showing a low dilatational amount due to insufficient transformation. It is most likely that the coarse columnar grains in cast slab are retained and untransformed high temperature δ-ferrite are not subjected to twice complete transformations. These retaining columnar grains in low grades of electrical steels can be used to improve magnetic properties through optimizing processing parameters.

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Transformation Texture in Hot-rolled Steel Sheets and Its Quantitative Prediction

Cited by 18 publications

References 24 publications

Crystallographic Reconstruction Study of the Effects of Finish Rolling Temperature on the Variant Selection During Bainite Transformation in C-Mn High-Strength Steels

Crystallographic Reconstruction Study of the Effects of Finish Rolling Temperature on the Variant Selection During Bainite Transformation in C-Mn High-Strength Steels

<i>In Situ</i> EBSD Analysis on the Crystal Orientation Relationship between Ferrite and Austenite during Reverse Transformation of an Fe-Mn-C Alloy

Transformation Delay and Texture Memory Effect of Columnar Grained Cast Slab in Low Grades Non-oriented Electrical Steels

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