Investigation on Improvement of Center Porosity with Heavy Reduction in Continuously Cast Thick Slabs

Xu, Zhigang; Wang, Xinhua; Jiang, Min

doi:10.1002/srin.201600061

Cited by 20 publications

(16 citation statements)

References 31 publications

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“…Internal central segregation and porosity are common defects in the continuous casting (CC) slab and these defects affect the internal quality of the final rolled plate. Reducing the defects is essential for achieving satisfactory properties in the products [1]. Many methods including the low superheat pouring technique [2], the Electromagnetic Stirring (EMS) [3] and the ultrasonic vibration [4] have been implemented to reduce the defects.…”

Section: Introductionmentioning

confidence: 99%

Experimental Investigation of Solidification in the Cast Mold with a Consumable Cooler Introduced Inside

Niu

Liu

et al. 2019

Metals

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The microstructure is of great significance for the stability and mechanical performance of the cast slab. Recently, an innovative technology of feeding a consumable cooler into the mold has been proposed to improve the internal quality of castings. But the mechanism is not clear. In the present work, a water-cooled transparent laboratory equipment was set up and solidification of NH4Cl-70%H2O solution was studied to observe the in-situ growth and sedimentation of crystals. The experiments were conducted with and without adding a consumable cooler. Morphology variation of the solidification structure was visualized and temperature distribution during the process was recorded. Results show that introduction of the consumable cooler significantly reduces the temperature of the central zone. Melting of the consumable cooler can supply a large quantity of equiaxed crystals, which prevent the growth of columnar dendrites and thereby promote columnar to equiaxed transition (CET). Moreover, the enhanced convection shows an effect of grain refinement.

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Section: Introductionmentioning

confidence: 99%

Experimental Investigation of Solidification in the Cast Mold with a Consumable Cooler Introduced Inside

Niu

Liu

et al. 2019

Metals

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“…However, due to the increased solidification time for casting steel with a large section size, its internal porosities become more serious with the presence of coarser cast structure [4,18]. Under condition of large components that were produced by rolling or forging with a relatively low compression ratio [11,[19][20][21], the serious internal porosities in large section size casting steel could not be easily eliminated, which seriously influences the mechanical properties of the final products. Meanwhile, as one of the main counter measures of the internal porosities, the traditional mechanical soft reduction (SR) [22,23] was proved to be insufficient on significantly improving the serious internal porosities in the casting steel with a large section size.…”

Section: Introductionmentioning

confidence: 99%

“…As an effective counter measure of internal defects in continuous casting steel, HR has attracted more and more researchers' attention with the rapidly increased demand for large components in the large equipment manufacturing industry in recent years. Some theoretical and experimental investigations were carried out recently for studying the improving effect of HR on porosity and other internal defects in continuous casting bloom [28,29], billet [30], or slab [19][20][21], and some new HR technologies were then proposed and applied. By establishing a three-dimensional (3D) thermal-mechanical coupled model, the present authors [28] studied the deformation behavior of continuous casting bloom during HR and developed the two-stage sequential heavy reduction technology.…”

Section: Introductionmentioning

confidence: 99%

Deformation Behavior of Internal Porosity in Continuous Casting Wide-Thick Slab during Heavy Reduction

Zhu

2019

Metals

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Heavy reduction (HR) is a novel technology that could effectively improve the internal porosities and other internal quality problems in continuously cast steel, during which a large reduction deformation is implemented at and after the strand solidification end. In the present paper, non-uniform solidification of the wide-thick slab was calculated with a two-dimensional (2D) heat transfer model. Based on the predicted temperature distribution at the solidification end of the casting strand, a three-dimensional (3D) thermal-mechanical coupled model was developed for investigating the deformation behavior of the internal porosities in wide-thick slab during HR. An Arrhenius-type constitutive model for the studied steel grade was derived based on the measured true stress-strain with single-pass thermosimulation compression experiments and applied to the 3D thermal-mechanical coupled model for improving the calculation accuracy. With the developed 3D thermal-mechanical coupled model, deformation behavior of the two artificial porosities located at the slab center of 1/2 width and 1/8 width during HR was investigated under different condition of HR deformation, HR start position, and HR reduction mode. Based on the calculated porosity closure degree (ηs) and the corresponding equivalent strain (εeq) under different HR conditions, a prediction model that describes the quantitative relationship between ηs and εeq was derived for directly and accurately evaluating the process effect of HR on improving the internal porosities in wide-thick slab.

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“…Recently, a novel rolling technology called Hot‐core Heavy Reduction (HHR) has been developed to refine the center microstructure in continuously cast slab, which is directly rolling slab at the end of solidification and with large temperature gradient. Hot‐core Heavy Reduction (HHR) is a rolling process with large deformation resistance gradient . When rolling process starts, the center temperature of the slab is still high, but surface temperature decreases very quickly.…”

Section: Introductionmentioning

confidence: 99%

Evolution of Austenite Grain Size in Continuously Cast Slab during Hot‐Core Heavy Reduction Rolling Process Based on Hot Compression Tests

Gong

Wang

et al. 2018

steel research int.

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A novel technology called Hot‐core Heavy Reduction (HHR) has been developed to refine the center microstructure of continuously cast slabs, which is rolling at the end of solidification and with large temperature gradient. In this work, plant trials of Hot‐core Heavy Reduction rolling is conducted and show the significant refinement effect on the center microstructure of continuously cast slab. Dynamic recrystallization behavior in Nb–Ti microalloyed slab at high deformation temperature of 1000–1300 °C is further understood using Gleeble‐3800 thermo‐mechanical simulator. The results show that all the austenite grains are largely refined after deformation in hot compression tests. Austenite grains present different morphologies under different deformation temperature. At the temperature of 1100 °C, austenite grains can be significantly refined with increase in the strain and strain rate. While at higher deformation temperature of 1300 °C, austenite grain size cannot be further refined but become coarse to some extent when strain increases to 0.8 and strain rate increases to 10 s−1. Moreover, the dynamic recrystallization model and austenite grain size model are established in the deformation process. Then, the dynamic recrystallization volume fraction and austenite grain size during HHR rolling process can be well reflected by the established models.

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Investigation on Improvement of Center Porosity with Heavy Reduction in Continuously Cast Thick Slabs

Cited by 20 publications

References 31 publications

Experimental Investigation of Solidification in the Cast Mold with a Consumable Cooler Introduced Inside

Experimental Investigation of Solidification in the Cast Mold with a Consumable Cooler Introduced Inside

Deformation Behavior of Internal Porosity in Continuous Casting Wide-Thick Slab during Heavy Reduction

Evolution of Austenite Grain Size in Continuously Cast Slab during Hot‐Core Heavy Reduction Rolling Process Based on Hot Compression Tests

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