Modelling-based Innovative Feeding Strategy for Beam Blanks Mould Casting Aimed at As-cast Surface Quality Improvement

Abstract

Within an investigation focused on effect of casting conditions on steel quality in an industrial beam blanks mould, different nozzle geometries were tested with Computational Fluid Dynamics modelling. The innovative nature of the work consisted in feeding with only one nozzle, whereas two nozzles in the flange-tip zone are commonly used. This configuration has the advantage of a simplified mono-slide gate casting layout, but single nozzle feeding can bring about risks of too high steel velocity in the mould, harmful for shell integrity and meniscus stability.Having in mind the mentioned constraints, different geometry solutions were checked and, to assess the solutions found, suitable indices were defined, related to flow conditions able to prevent slag entrapment at the meniscus, and hot-spotting at walls, harmful for the solid shell integrity.The modelling work gave general indications on undesired flow features and guidelines to improve reference conditions, involving number of holes and holes angle, size and shape. For the caster mould and the operating conditions under concern, a solution was found satisfying the indices, and expected to fulfil the quality requests. It consisted of a nozzle with a 50 mm diameter throat, a 50 mm× 60 mm elliptical lateral port inclined 25° downwards and a 20 mm-diameter bottom hole. A water model check with such a nozzle prototype validated the model supporting the solution identified to be used on plant.KEY WORDS: beam blanks; flow field; nozzle; cracks; shell remelting; slag entrapment. ForewordIn continuous casting of beam blanks, the occurrence of longitudinal surface cracks plays a relevant role in affecting as-cast quality. Not so many studies on surface crack occurrence in beam blanks are shown in literature. Lee and others, 1) within the as-cast beam blank shape (Fig. 1) identified the web and fillet region as mostly prone to crack formation, also noticing that shell formation is somewhat retarded at the flange-center region, due to the steel stream impingement from the feeding nozzle. The conclusions were gained based on a suitably defined crack susceptibility coefficient. Furthermore, Seok and Yoon 2) investigated the effect of steel composition on longitudinal crack formation. The most relevant results were the identification of: a) a mostly sensitive crack susceptibility range of carbon contents (0.12-0.13 wt.%); b) the effect of casting speed on crack formation (a linear relationship). Then, Hibbeler et al., 3) performed a thorough 3D thermo-mechanical analysis of beam blank steel solidification without accounting for liquid metal flow. A coupled thermal-mechanical model of steel casting was applied to accurately simulate casting of steel beam blanks, validated with plant measurements. An efficient local-global numerical procedure is given to integrate a realistic elasticvisco-plastic phase-dependent constitutive model implemented into the commercial package ABAQUS, and insights are provided into the mechanisms of shell failure triggered first by a thinner she...

Análise Do Fluxo Em Molde De Lingotamento Contínuo De Beam Blank: Simulação Computacional E Física

“…Por outro lado, a oscilação excessiva do menisco irá favorecer o entranhamento de escória. De Santis et al [7] sugerem que para se ter uma boa fusão do pó fluxante, a velocidade na região do menisco deve ser da ordem …”

Study on the Fluid Flow in a Semi-Open-Stream-Poured Beam Blank Continuous Casting Mold with Submerged Refractory Funnels by Multiphase Modeling

“…However, the difference between Figure 9b Under a certain bubble size, a longer float distance leads to a higher speed of bubbles at the slag/steel interface, which can increase the fluctuation of the meniscus. As discussed in [11], when a criterion is reached relating tangential velocities at the steel-slag interface, slag entrainment occurs. Meanwhile, a longer floating distance means that the air stays in contact with the liquid steel longer, which leads to more steel re-oxidation.…”

“…Chen et al [8], Seok andYoon [9], and Du et al [10] obtained the flow field and temperature distribution in beam blank molds using 3D coupled models of fluid flow and solidification. De Santis et al [11] tested different nozzle geometries with computational fluid dynamics modeling for an industrial beam blank mold and discussed the flow conditions. However, these studies only focused on full-protection pouring conditions and not on open-stream pouring [7][8][9][10][11].…”

Fluxo De Líquido Num Molde De Beam Blank E a Remoção De Inclusões

“…A utilização de duas válvulas submersas propicia a reduzir a assimetria do fluxo de fluido ao longo do molde (Peixoto et al [1]). Porém esta configuração traz dificuldades operacionais e até mesmo de projeto do sistema de alimentação (De Santis et al [2]). Entender as características de fluxo geradas pelo sistema de alimentação adotado em moldes de beam blank é importante para a definição das melhores condições operacionais, visando maior produtividade, maior limpidez do aço e segurança operacional (Beaton et al [3]).…”