Control of Shrinkage Porosity and Spot Segregation in Ø195 mm Continuously Cast Round Bloom of Oil Pipe Steel by Soft Reduction

Li, Liang; Zhang, Zhonghua; Li, Bo; Peng, Lan; Zhang, Jiaquan

doi:10.3390/met11010009

Cited by 16 publications

(5 citation statements)

References 20 publications

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“…The previous research studies [25][26][27][28][29] have shown that the reduction technology can effectively improve the internal quality of the billet, reducing the center porosity and segregation, which is one of the key technologies to improve the slab internal quality during the continuous casting production process. Li et al [30] developed a two-dimensional thermal-mechanical coupled model to investigate the deformation behavior of round bloom during soft reduction (SR) in the reduction force mode. They found that the shrinkage porosity in the center of the round bloom almost vanished with the implementation of reduction process.…”

Section: Basic Principle Of Reduction Technologymentioning

confidence: 99%

“…Moreover, the center porosity of rolled bars was reduced from 2.0-2.5 to 1.0 by using integrated HR technology. Previous research reports [7,30,45,46] have shown that the reduction technology can change the internal structure of the billet and improve its internal quality. The development history of reduction technology is shown in Table 3.…”

Section: Development History 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: Basic Principle Of Reduction Technologymentioning

confidence: 99%

Section: Development History 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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“…Recently, large billets have been extensively applied in large-scale equipment, including wind power generation, large or extremely large-scale ring products, the petrochemical industry, and other equipment [ 1 ]. Nevertheless, the large round billet in continuous casting is prone to problems such as center porosity [ 2 , 3 ], shrinkage cavity [ 4 ], and macrosegregation [ 1 , 5 ] at the end of the solidification. The mold electromagnetic stirring (M-EMS) and the final electromagnetic stirring (F-EMS) [ 6 , 7 , 8 ] are popularly applied in the production of continuous casting of round billets to solve the above problems.…”

Section: Introductionmentioning

confidence: 99%

Numerical Simulation of the Effect of Solidified Shell Conductivity and Billet Sizes on the Magnetic Field with Final Electromagnetic Stirring in Continuous Casting

Tan

Song

et al. 2023

Materials

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Coupled with the results of a 2D heat transfer model, a 3D electromagnetic stirring round billet model is developed, which is considered for the difference in the conductivity of solidified shell and molten steel. The electromagnetic field distribution features of the billet and the effect of round billet sizes on the electromagnetic field are investigated. It is found that as the solidified shell conductivity of the Φ600 mm round billet increases from 7.14 × 105 S·m−1 to 1.0 × 106 S·m−1, the magnetic induction intensity decreases and the maximum value of electromagnetic force drops from 7976.26 N·m−3 to 5745.32 N·m−3. The magnetic induction intensity on the center axis of the stirrer rarely changes in the range of Φ100–Φ200 mm. With the increase in the round billet from Φ300 mm to Φ600 mm, the magnetic induction intensity and the electromagnetic force on the center axis of the stirrer decrease slowly and then significantly. In the range of 2–8 Hz, as the current strength reaches its maximum, the electromagnetic force can be increased by increasing the current frequency for round billets of Φ100–Φ500 mm, while there is an optimal current frequency for round billets larger than Φ600 mm.

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“…From the perspective of structure and performance requirements on finished products, on the one hand, the high-carbon and high-sulfur steel has a large tendency to shrink and crack in the process of continuous casting, which will easily result in the failure of ultrasonic detection. Additionally, its large segregation tendency due to its inherent chemistry can easily cause poor stability of the microstructures and mechanical properties of the subsequent rolling products [ 3 , 4 , 5 ]. Therefore, an in-depth understanding of the as-cast steel microstructure and its defect characteristics are of great significance on developing a continuous casting practice of this type of high-class steel.…”

Section: Introductionmentioning

confidence: 99%

Effect of Flow Field Optimization of an Asymmetric Multi-Strand Tundish on the Quality Consistency of Cracking Con-Rod Steel

et al. 2022

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Cracking con-rod is an advanced high-precision connecting structure based on brittle expansion, breaking and reconnection of steel, to solve the problem of assembly circle missing. High carbon micro-alloyed steel C70S6, as a dominant material for the production of cracking con-rod, has extremely strict requirements on non-metallic inclusions in steel and microstructure stability. Continuous casting tundish plays an important role in removing large-sized inclusions and stabilizing casting quality. Aiming at the inconsistent casting quality of C70S6 steel produced by a three-strand asymmetric tundish and the frequent occurrence of slag entrapment problems in Xining Special Steel, the tundish structure was optimized by means of physical modelling combined with numerical simulation, and the quality of the bloom castings and subsequent hot-rolled products before and after optimization were compared based on volume production. The results show that a new flow control design to the tundish can effectively improve the consistency of its metallurgical effect for each of the three strands and the following overall product quality, in which the flow field and temperature field in the tundish are more uniform. This is due to the adoption of a vortex inhibitor and an optimized wall structure according to the measured RTD curve, ink trajectory and numerical simulation on the 3-D streamline contours and temperature distribution in the tundish. The peak concentration of outlet 1 is decreased from 6.5 before optimization to less than 2.0 after optimization, which means the elimination or alleviation of the local short-circuit flow. The maximum temperature difference of C70S6 molten steel measured at the outlets of the tundish three strands is decreased from 2–5 °C to 1–3 °C, which is in good agreement with the numerical simulation results. The difference in columnar crystal ratio of the corresponding bloom castings is decreased from 2.27–3.17% to 1.26–1.85%, and the consistency of central carbon segregation index is also significantly improved. In addition, the difference in oxygen content among the three strand blooms is decreased from 1.7–3.5 ppm to 0.8–1.9 ppm. As a result, the overall mechanical properties and microstructure stability of the hot-rolled products are improved statistically, in which the hardness fluctuation is decreased from 84 HBW to 60 HBW, the inclusion grade of types B + C + D + Ds is reduced to 1.105, and the occurrence rate of Ds dropped to 0.118%. Accordingly, the failure rate of the cracking con-rod is controlled stably within 4‰, and the fracture is generally smoother than that before tundish optimization. In summary, the flow field optimization to a multi-strand asymmetric tundish has a clear effect on improving the overall quality of its bloom castings and rolled products, which should be paid more attention industrially. Meanwhile, the present study provides a reliable theoretical and experimental reference for the improvement of metallurgical effects of an asymmetric-typed tundish commonly used in special steel production.

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Control of Shrinkage Porosity and Spot Segregation in Ø195 mm Continuously Cast Round Bloom of Oil Pipe Steel by Soft Reduction

Cited by 16 publications

References 20 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

Numerical Simulation of the Effect of Solidified Shell Conductivity and Billet Sizes on the Magnetic Field with Final Electromagnetic Stirring in Continuous Casting

Effect of Flow Field Optimization of an Asymmetric Multi-Strand Tundish on the Quality Consistency of Cracking Con-Rod Steel

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