Thermomechanical Analysis of the Effects of Water Distribution on Cracks during Vertical Continuous Casting under Soft Reduction Conditions

Abstract

In the production process of continuous casting slab, the unreasonable secondary cooling system can lead to serious crack defects. This study focuses on the problem of cracks in nuclear power stainless steel produced by vertical continuous casting under soft reduction conditions. Based on the actual production process parameters, the thermomechanical finite element model was established to investigate the effects of water distribution in the secondary cooling zones on cracks by using ProCAST. The results show that the stress concentration is obvious under the original process, especially the positions of 4 mm below the wide surface and 6 mm below the narrow surface. It is easy to generate cracks, and the area with the highest hot-tearing index is approximately 26 cm2. In addition, the secondary cooling system is adjusted based on the existing problems of the original process. The temperature of the casting slab rises by about 15°C at the solidification end point, and the length of the liquid core increases by about 0.5 m when the quantity of the water flow decreases in zone 2 and zone 3. The stress concentration is alleviated, and the possibility of cracking is reduced. Especially, it is evident that the proportion of water on the loose side margin increases from 40% to 45%, while the proportion of water on the fixed side margin of zone 3 is adjusted from 56% to 60%.

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

“…Centerline segregation is directly related to the transport phenomenon, which in turn is associated with fluid flow, heat transfer, and steel composition. 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.…”

Effect of cooling uniformity on the internal reduction efficiency of a slab

“…Rogberg and Ek [17] developed a mathematical model of liquid flow velocity in strands under soft reduction. Yao et al [18] studied the influence of the secondary cooling water distribution on the cracks of the slab produced by a vertical continuous caster based on a thermo-mechanical coupling numerical simulation and optimised the cooling process to improve the slab quality based on the simulation results. Wu et al [19] simulated slab bulging under the condition of non-uniform cooling.…”