Improvement of Semi-macro Segregation in Continuously Cast Slabs by Controlled Plane Reduction

Zeze, Masafumi; Misumi, Hideyuki; Nagata, Shuuji; Mizoguchi, Shouzou; Shirai, Tokinari; Tsuneoka, Akira

doi:10.2355/tetsutohagane1955.87.2_77

Cited by 10 publications

(7 citation statements)

References 9 publications

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“…The billets with large sections have more serious internal porosity than the small section billets, which is difficult to eliminate [41]. Nippon Steel proposed NS Bloom Large Reduction Technology [42]. They used convex rolls to implement a large reduction amount on the solidified bloom, which significantly improved the central segregation and reduced the internal defects in rolled products.…”

Section: Development History Of Reduction Technologymentioning

confidence: 99%

“…There are two types of SR technology, including static and dynamic SR. Static SR refers to implementing the reduction amount at a specific location, while in the dynamic SR the position of reduction can be adjusted by changing of process parameters and the size of roll gap can be controlled. The two different types of reduction forces acted on the solid-liquid two phase zone during the implementation of reduction technology [42,51]: the first is thermal stress, which is responsible for the volume shrinkage at the solidification end. However, the disadvantage of this method is that it is not favorable for the growth of equiaxed crystals and the energy conservation; the other is mechanical stress, which compensates for the solidification shrinkage of the billet.…”

Section: Classification Of Reduction Technologymentioning

confidence: 99%

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Application Status and Development Trend of Continuous Casting Reduction Technology: A Review

Nian

Zhang

et al. 2022

Processes

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Continuous casting is a dominant steelmaking process due to its steady-state nature, enhanced yield of steel production, and low consumption of energy and manpower. However, the production of defect-free cast products is still a big challenge, as the internal defects, including macro-segregation of alloying elements, cracks, and pores, can be easily formed during the solidification process, which seriously deteriorates the microstructure and mechanical properties of the cast products. Therefore, this paper puts forward the common solutions to overcome these problematic issues. The reduction technology can effectively improve the center segregation of the billet, bloom, and slab. The history of the development of the reduction technology is summarized and classified according to the variations in research trend. Furthermore, the basic principles and parameters of reduction technology are described to implement them in the actual production process. This paper compares the similarities and differences between soft reduction (SR) and heavy reduction (HR) technologies with a particular focus on the theoretical research of HR technology and further elaborates the key parameter and equipment problems during implementation of HR. Moreover, this paper also considers the HR technology adopted by Baosteel as a case study, which helped to put forward some viewpoints for the future development of reduction technology.

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Section: Development History Of Reduction Technologymentioning

confidence: 99%

Section: Classification Of Reduction Technologymentioning

confidence: 99%

Application Status and Development Trend of Continuous Casting Reduction Technology: A Review

Nian

Zhang

et al. 2022

Processes

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show abstract

“…The latent heat was taken into account between zero and 1.0 of solid fraction. In addition, Sh, which is a function of V and flow velocity, 29) was given as a constant, 0.8 28) due to the small influence of Sh on the predicted ECR, as will be described later. Figure 1 shows a schematic diagram of the distribution of l eff applied in the solid-liquid coexisting zone.…”

Section: Methods For Calculatingmentioning

confidence: 99%

Prediction of Equiaxed Crystal Ratio in Continuously Cast Steel Slab by Simplified Columnar-to-Equiaxed Transition Model

Shibata¹,

Itoyama²,

Kishimoto³

et al. 2006

ISIJ Int.

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“…Similarly, the steel sheet applied to a shadow mask material, micro segregation of Ni affects on etching property for making numerous and extremely fine holes into this alloy sheet. 2) Several means for improvement of macro-or micro segregation in a strand slab caster have been taken such as electro-magnetic stirring, 3,4) mechanical working with a light reduction ratio on a slab or bloom at the final stage of solidification, [5][6][7] or optimization of various casting parameters. 8,9) Furthermore, homogenization heat treating of the as cast slab at the very high temperature for a very long period of heating time or combination of hot rolling and homogenization treating is also practiced for such critical applications of steels as described above.…”

Section: Introductionmentioning

confidence: 99%

Effects of Dynamic Recrystallization on .GAMMA. Grain Refinement and Improvement of Micro Segregation of As Cast Austenite in 9% Ni Steel

et al. 2005

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Effects of dynamic recrystallization on g grain refinement and improvement in micro segregation of elements such as Ni and Mn of as cast austenite in 9 % Ni steel were investigated by two kinds of experimental methods. The first one was a hot compression test using the specimens prepared from the strand cast slab and the hot rolled plate of 9 % Ni steel, and the other was a hot tensile straining test in the austenitic region after levitation melting and solidification. In the hot compression test, variations in onset strain and flow stress of steady state flow of dynamic recrystallization with hot deformation conditions were investigated. The onset strain was found to decrease below 0.25 at the temperatures above 1 523 K and the strain rate below 1ϫ10 Ϫ2 s Ϫ1. The activation energy value obtained from steady state flow stress was 421 kJ/mol. Dynamically recrystallized g grain size in as cast austenite of this steel was controlled simply by Z value with no dependence on the initial g grain size. This beneficial feature of dynamic recrystallization was confirmed by the experiment of tensile straining in austenite formed after levitation melting and solidification, where extremely coarse initial g grain size of around 1.9 mm was markedly refined down to 140 mm by straining such a small strain as 0.40. Micro segregation ratio of Ni and Mn in the strand cast 9 % Ni steel examined by EPMA analysis was 1.20 and 1.36, respectively. These values were found to decrease continuously with reduction in strain rate in hot deformation of austenite. That is, dynamic recrystallization in austenite taken place at lower strain rate deformation is much more effective for homogenization of segregated elements compared with high strain rate deformation.

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Improvement of Semi-macro Segregation in Continuously Cast Slabs by Controlled Plane Reduction

Cited by 10 publications

References 9 publications

Application Status and Development Trend of Continuous Casting Reduction Technology: A Review

Application Status and Development Trend of Continuous Casting Reduction Technology: A Review

Prediction of Equiaxed Crystal Ratio in Continuously Cast Steel Slab by Simplified Columnar-to-Equiaxed Transition Model

Effects of Dynamic Recrystallization on .GAMMA. Grain Refinement and Improvement of Micro Segregation of As Cast Austenite in 9% Ni Steel

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