Development of the hard reduction
method in the No. 3 bloom caster
at Kobe works, Kobe Steel

Ebina, Kiyoshi; Fujii, Katsuji; Shimono, S.; Toyoshima, Shiro; Nakayama, Kiminori; Takagi, Isao

doi:10.1051/metal/199289090783

Cited by 7 publications

(6 citation statements)

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“…The reduction efficiency increases as the flatness ratio (Fr), the volume ratio (Vr), the contact length ratio (Sr) and roll diameter become larger. [7][8][9]12) …”

Section: Processmentioning

confidence: 99%

“…Decisive for the success of soft-reduction process is that the position of the crater end or the area with an optimum solid fraction in the strand center is exactly determined for the regarded steel grade among all casting conditions, and that reduction of the strand thickness is controlled with great precision. [3][4][5][6][7][8][9][10][11] A general problem in billet soft-reduction is that a only comparatively small part of the applied reduction amount is transmitted to the liquid core, while the greater rest deforms the sidewalls. This is further aggravated by the distribution of temperature over the cross section and the deformation resistance of the sidewalls leading to an increase of force required for a certain reduction amount.…”

Section: Processmentioning

confidence: 99%

“…The solidification of the segregated residual melt in these channels results in the formation of macro-segregation as V-segregation and spot-like center segregation. 14,15) The basic idea of any kind of soft-reduction is to suppress the formation of macro-segregation by compensation of the shrinkage occurring during solidification and interrupt the suction flow of the residual melt 7,10) (Fig. 1).…”

Section: Introductionmentioning

confidence: 99%

“…Aside from electromagnetic stirring and casting with a low superheat, intensive cooling of the strand in the upper range of secondary cooling zone has, above all, proved to be very effective in reducing segregation in continuously cast billets. 1) Soft-reduction of the strand in the final stages of solidification, a method used successfully for suppressing center segregation and porosity in slab and bloom casting, [2][3][4][5][6][7][8][9][10][11][12][13] offers a possible alternative for producing material with a low segregation level especially in the case of steels that, due to their crack and distortion susceptibility, cannot undergo intensive cooling.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Principles of Billet Soft-reduction and Consequences for Continuous Casting

Thome

Harste

2006

ISIJ Int.

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“…The reduction efficiency increases as the flatness ratio (Fr), the volume ratio (Vr), the contact length ratio (Sr) and roll diameter become larger. [7][8][9]12) …”

Section: Processmentioning

confidence: 99%

Section: Processmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Principles of Billet Soft-reduction and Consequences for Continuous Casting

Thome

Harste

2006

ISIJ Int.

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“…The SR is generally applied to the central segregation forming region. The suitable reduction region of SR is different for distinct steel grades [4][5][6][7][8]. As reported by Thome and Karste [9], the SR should be conducted without creating internal cracks.…”

Section: Introductionmentioning

confidence: 99%

Finite Element Analysis of Dynamic Recrystallization of Casting Slabs during Hot-Core Heavy Reduction Rolling Process

Gong

et al. 2020

Metals

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Hot-core heavy reduction rolling (HHR2) is an innovative technology, where a two-high rolling mill is installed after the solidification end of a strand, which can significantly eliminate the core defects of the slab. The mill exhibits a heavy reduction ratio, which promotes the dynamic recrystallization (DRX) of the slab. This study aims to optimize the parameters of the HHR2 process considering the effect of DRX on microstructure homogeneity. The secondary development of commercial software DEFORM-3D is conducted to calculate the deformation and DRX behavior of HHR2 for different reduction ratios. The parameters of DRX volume fraction and DRX grain size are compared, and finer DRX grains are obtained when the greater reduction ratios are conducted in HHR2. Then, corresponding to the deformation conditions in the HHR2, the thermal–mechanical simulations are conducted on the Gleeble3800 to obtain the average grain sizes before and after this process. When the reduction amount increases from 20 mm to 50 mm, the difference of average grain size between the core and the surface reduces by 52%. In other words, appropriately enhancing the reduction ratio is helpful to reduce the average austenite grain and promote the microstructure uniformity of the slab. These results provide some valuable information on the design of deformation parameters for HHR2.

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Final solidification, centre segregation and precipitation phenomena in continuously cast round billets

Jacobi¹,

Wünnenberg²

1997

Steel Research

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Archimedes’ principle was applied to strand lengths of up to 14 m of round 177 mm diameter billets to determine cavity volume V (in cm3/m) for a series of tubemaking steels. Under steady state casting conditions, V depends primarily on the chemical composition and solidification behaviour of the steels. Averages ranged up to in an extreme case (bearing steel; vC = 2.0 m/min). Stopping the strand and abrupt lowering of withdrawal speed made it possible to artificially induce individual shrinkage cavities with peak values of V = 45 cm3/m. In the round mould, subsequent necking of the liquid crater is initiated in this process. Whisker‐like and icicle‐like dendrites can be observed in horizontally formed macroscopic shrinkage cavities. The liquid crater is broken off by periodic bridging (the mini‐lingot model). As permeability decreases, the bridges deflect downward in a U‐shape under the ferrostatic load. The residual inter‐dendritic melt is squeezed out in this plastic deformation process. Some bridges ultimately break. This interpretation is based on comprehensive CMA studies and concentration maps. Cores taken from the centre of a strand of bearing steel were submitted to various heat treatments between 1100 and 1350°C. Homogenization occurs below solidus (T < 1225°C). Carbides dissolve and sulfides become globular. Spatial segregation, on the other hand, increases, above solidus. In the extreme case at 1350°C/30 h, the residual melt at the grain boundaries migrates practically completely from the surface zone to the centre of the cylindrical sample (40 mm diameter). The propellent forces for this macro‐heterogenization are provided by the activity gradient from the cylindrical surface to the centre and minimization of interface energy γ/I.

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Development of the hard reduction method in the No. 3 bloom caster at Kobe works, Kobe Steel

Cited by 7 publications

References 0 publications

Principles of Billet Soft-reduction and Consequences for Continuous Casting

Principles of Billet Soft-reduction and Consequences for Continuous Casting

Finite Element Analysis of Dynamic Recrystallization of Casting Slabs during Hot-Core Heavy Reduction Rolling Process

Final solidification, centre segregation and precipitation phenomena in continuously cast round billets

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