Influence of Soft Reduction with One-piece Rolls on Center Segregation in Continuously Cast Slabs.

Ogibayashi, Shigeaki; Kobayashi, Masayuki; Yamada, Mamoru; Mukai, Toshiki

doi:10.2355/isijinternational.31.1400

Cited by 36 publications

(18 citation statements)

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“…On the other hand, external deformation can be beneficial such as the application of a 'soft reduction', a small rolling reduction (e.g. a few % strain) near to the end of the sump to compensate for solidification shrinkage and reduce centreline segregation and porosity [6][7][8]. Despite this importance, there remains only limited understanding of the mechanical behaviour of the mushy-zone in steels and, in particular, of their microstructural response to load and how this leads to defects.…”

Section: Introductionmentioning

confidence: 99%

Dilatancy in semi-solid steels at high solid fraction

et al. 2017

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The study of mushy-zone deformation in steels is important for limiting defect formation in continuous casting. Here, we use in situ synchrotron radiography to quantify the shear deformation mechanisms of an equiaxed carbon steel at a solid fraction >0.9 and to understand how these mechanisms lead to casting defects. We show that the grain assembly undergoes shear-induced dilation (Reynolds' dilatancy) which opens liquid-filled fissures and cracks at high solid fraction. We further show a complex interaction between grain rearrangement, grain deformation and local coarsening, where rearrangement reduces the grain-grain contact area and coordination number which alters the stress network and also drives coarsening as grains move apart.

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Section: Introductionmentioning

confidence: 99%

Dilatancy in semi-solid steels at high solid fraction

et al. 2017

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“…[1][2][3][4][5][6][7][8][9][10] The principle of SR is to impose a reasonable reduction rate/ amount on the solidification end of the strand for compensating liquid core shrinkage and preventing the soluteenriched liquid flowing toward the center of the strand without creating internal cracks. 1,2,4) In bloom SR process, the reduction is usually executed by 6-10 withdrawal units which are arranged in the air cooling zone with intervals of 1.0-3.5 m. Therefore the reduction interface is discontinuous, and the SR amount is generally selected as the primary control parameter during the bloom SR process.…”

Section: Introductionmentioning

confidence: 99%

Analysis and Application of Soft Reduction Amount for Bloom Continuous Casting Process

Luo

Zhu

2014

ISIJ Int.

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Based on the principle of solidification shrinkage compensation, a soft reduction amount calculation method was derived for bloom continuous casting process, and the bearing steel GCr15 was chosen as specific research steel to describe calculation process in detail. A two-dimensional heat transfer model was built to predict the solidification process of bloom, and the material properties of GCr15 were derived by weighted averaging of the phase fractions. The predicted temperature and shell thickness were verified by a thermal infrared camera and nail shooting results, respectively. The soft reduction amount of typical high carbon alloy steel blooms were calculated and discussed. The plant results showed that after the application of soft reduction to the bloom, centerline segregation and "V" type segregation were improved significantly. The carbon and sulfur ratios of the bloom centerline were reduced from 1.39 to 1.09 and 2.14 to 1.29, respectively.

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“…MECHANICAL soft reduction (MSR) has been shown in industrial practice to reduce centerline/axial segregation in slab and bloom castings [1][2][3][4][5][6][7][8][9][10] ; however, control of the MSR process remains a trial and error process in plant operations. Empirical knowledge ( Figure 1) has shown that satisfactory MSR efficiency can be achieved when MSR is positioned correctly on the strand and carried out with the appropriate reduction intensity.…”

Section: Introductionmentioning

confidence: 99%

Using a Two-Phase Columnar Solidification Model to Study the Principle of Mechanical Soft Reduction in Slab Casting

Domitner

Ludwig

2011

Metall Mater Trans A

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A two-phase columnar solidification model is used to study the principle of mechanical soft reduction (MSR) for the reduction of centerline segregation in slab casting. The two phases treated in the model are the bulk/interdendritic melt and the columnar dendrite trunk. The morphology of the columnar dendrite trunk is simplified as stepwise growing cylinders, with growth kinetics governed by the solute diffusion in the interdendritic melt around the growing cylindrical columnar trunk. The solidifying strand shell moves with a predefined velocity and the shell deforms as a result of bulging and MSR. The motion and deformation of the columnar trunks in response to bulging and MSR is modeled following the work of Miyazawa and Schwerdtfeger from the 1980s. Melt flow, driven by feeding of solidification shrinkage and by deformation of the strand shell and columnar trunks, as well as the induced macrosegregation are solved in the Eulerian frame of reference. A benchmark slab casting (9-m long, 0.215-m thick) of plain carbon steel is simulated. The MSR parameters influencing the centerline segregation are studied to gain a better understanding of the MSR process. Two mechanisms in MSR modify the centerline segregation in a slab casting: one establishes a favorable interdendritic flow field, whereas the other creates a non-divergence-free deformation of the solid dendritic skeleton in the mushy region. The MSR efficiency depends not only on the reduction amount in the slab thickness direction but also strongly on the deformation behavior in the longitudinal (casting) direction. With enhanced computation power the current model can be applied for a parameter study on the MSR efficiency of realistic continuous casting processes.

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Influence of Soft Reduction with One-piece Rolls on Center Segregation in Continuously Cast Slabs.

Cited by 36 publications

References 1 publication

Dilatancy in semi-solid steels at high solid fraction

Dilatancy in semi-solid steels at high solid fraction

Analysis and Application of Soft Reduction Amount for Bloom Continuous Casting Process

Using a Two-Phase Columnar Solidification Model to Study the Principle of Mechanical Soft Reduction in Slab Casting

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