Effects of residual elements during the casting process of steel production: a critical review

Steelmaking-refining-Continuous Casting (SCC) is a key process in iron and steel production. SCC scheduling is to determine an optimal schedule for the SCC process, which is a worldwide and important problem. High-quality SCC scheduling methods will help to allocate production resources effectively and increase the productivity. However, dynamic events (e.g. machine breakdown) may happen in the realistic SCC process, which will make the SCC schedule inexecutable or not optimal. In this case, SCC rescheduling is essential in order to obtain a new optimal schedule suitable for the current production environments. The SCC rescheduling can be modeled as hybrid flowshop rescheduling. In this paper, an Improved Imperialist Competitive Algorithm (IICA) is proposed to address the SCC rescheduling. In the proposed IICA, an empire initialization is first devised for constructing an initial population with diversity and certain quality. Moreover, multiswap-based local search and imperialist competition are designed to improve the exploitation ability of the IICA, while revolution and restart strategy are devised to enhance the exploration ability of the IICA. Comparison experiments with three kinds of ICA have shown the efficiency of the IICA.

Download Full-text

Characterization of steel billet scales generated during the continuous casting process in SIDERPERU steel plant

Hyperfine Interactions ◽

10.1007/s10751-021-01778-8 ◽

2021 ◽

Vol 242 (1) ◽

Author(s):

L. E. Borja-Castro ◽

A. Bustamante Dominguez ◽

M. I. Valerio-Cuadros ◽

R. A. Valencia-Bedregal ◽

H. A. Cabrera-Tinoco ◽

...

Keyword(s):

Room Temperature ◽

Steel Production ◽

Casting Process ◽

Steel Plant ◽

X Ray Diffraction ◽

Hyperfine Fields ◽

X Ray ◽

Billet Surface ◽

T Values

AbstractTons of waste is produced during iron steel’s industrial production, creating environmental pollution. This work aims to characterize the steel scale formed on the billet surface during the last step of steel production in the SIDERPERU steel plant. Scanning Electron Microscopy (SEM) shows stacked layers one above the other on steel billets scales surface. Energy Dispersive X-ray (EDX) and X-ray Fluorescence (XRF) reveal the high content of Fe and O, with Ca, Si, Mn, and Cr as minority elemental compounds. X-ray Diffraction (XRD) shows FeO, α-Fe2O3 and Fe3O4 as crystallographic phases. Magnetometry reveals Verwey transition and paramagnetic signals that screen the Morin transition. Mössbauer Spectroscopy at room temperature displays magnetic and non-magnetic parts. The non-magnetic part has the hyperfine parameters corresponding to predominant nonstoichiometric wustite. Octahedral (Fe+2/Fe3+) and tetrahedral Fe+3 hyperfine fields of 46.0 and 49.4 T values respectively are associated to nonstoichiometric magnetite and another sextet with a hyperfine field of 52.0 T is related to hematite.

Download Full-text

On Modelling Parasitic Solidification Due to Heat Loss at Submerged Entry Nozzle Region of Continuous Casting Mold

Metals ◽

10.3390/met11091375 ◽

2021 ◽

Vol 11 (9) ◽

pp. 1375

Author(s):

Alexander Vakhrushev ◽

Abdellah Kharicha ◽

Menghuai Wu ◽

Andreas Ludwig ◽

Yong Tang ◽

...

Keyword(s):

Continuous Casting ◽

Steel Slag ◽

Phase Interface ◽

Steel Production ◽

Submerged Entry Nozzle ◽

Casting Process ◽

Material Model ◽

Slag Layer ◽

Continuous Casting Mold ◽

High Production Rate

Continuous casting (CC) is one of the most important processes of steel production; it features a high production rate and close to the net shape. The quality improvement of final CC products is an important goal of scientific research. One of the defining issues of this goal is the stability of the casting process. The clogging of submerged entry nozzles (SENs) typically results in asymmetric mold flow, uneven solidification, meniscus fluctuations, and possible slag entrapment. Analyses of retained SENs have evidenced the solidification of entrapped melt inside clog material. The experimental study of these phenomena has significant difficulties that make numerical simulation a perfect investigation tool. In the present study, verified 2D simulations were performed with an advanced multi-material model based on a newly presented single mesh approach for the liquid and solid regions. Implemented as an in-house code using the OpenFOAM finite volume method libraries, it aggregated the liquid melt flow, solidification of the steel, and heat transfer through the refractory SENs, copper mold plates, and the slag layer, including its convection. The introduced novel technique dynamically couples the momentum at the steel/slag interface without complex multi-phase interface tracking. The following scenarios were studied: (i) SEN with proper fiber insulation, (ii) partial damage of SEN insulation, and (iii) complete damage of SEN insulation. A uniform 12 mm clog layer with 45% entrapped liquid steel was additionally considered. The simulations showed that parasitic solidification occurred inside an SEN bore with partially or completely absent insulation. SEN clogging was found to promote the solidification of the entrapped melt; without SEN insulation, it could overgrow the clogged region. The jet flow was shown to be accelerated due to the combined effect of the clogging and parasitic solidification; simultaneously, the superheat transport was impaired inside the mold cavity.

Download Full-text

Modeling of the Steel Flow and Non-Metallic Inclusion Separation due to Flotation in a Six-Strand cc Tundish

Materials Science Forum ◽

10.4028/www.scientific.net/msf.706-709.1556 ◽

2012 ◽

Vol 706-709 ◽

pp. 1556-1561

Author(s):

Marek Warzecha

Keyword(s):

Continuous Casting ◽

Technological Development ◽

Three Dimensional ◽

Steel Production ◽

Casting Process ◽

Metallic Inclusion ◽

Continuous Casting Process ◽

Flow Through ◽

Steel Flow ◽

Physical Phenomena

Constantly increasing customers’ demands for the production of high and very high-quality steels, promote the intensive technological development of their production. Today, the dominating method of global steel production is continuous casting. A continuous casting plant includes the ladle turret, several steel ladles, a tundish, and a mold followed by a framework of rolls to support the strip. The tundish has become a very important metallurgical unit in the continuous casting process. Nowadays its role is not only to guaranty the link between the process of secondary metallurgy and the continuous casting process in the mould but it becomes an active metallurgical reactor. Therefore in recent years a lot of researches were done to establish a better understanding of the physical phenomena accompanying the steel flow through the tundish and non-metallic inclusion separation into the top slag cover. The article presents computational studies of the three-dimensional turbulent steel flow and non-metallic inclusions separation in a multi-strand tundish for steady-state casting conditions. Simulations of the steel flow in the tundish are performed with boundary conditions that are derived from the real casting process. The mathematical model used for simulations, was partly validated with experimental measurements. Numerical calculations are carried out by the finite-volume code Fluent using k-ε standard turbulence model. With the calculated flow field, micro-inclusions removal due to flotation to the coving slag is investigated numerically. For the particle separation at the interface a modified boundary condition is implemented.

Download Full-text

Evaluation of Functionally Graded Ceramic Crucible for Induction Melting of Titanium Based Alloys

Materials Science Forum ◽

10.4028/www.scientific.net/msf.730-732.769 ◽

2012 ◽

Vol 730-732 ◽

pp. 769-774 ◽

Cited By ~ 3

Author(s):

Fernando Gomes ◽

Joaquim Barbosa ◽

Carlos Silva Ribeiro

Keyword(s):

Thermal Shock ◽

Thermal Shock Resistance ◽

Slip Casting ◽

Casting Process ◽

Functionally Graded ◽

Induction Melting ◽

Chemical Contamination ◽

Melting Crucible ◽

Residual Elements ◽

Shock Resistance

During the last years a very significant effort to develop a melting crucible for induction melting of Ti based alloys at competitive cost has been carried out by many researchers, where the authors are included. Results obtained so far have shown that no material accomplishes the melting crucibles two main demands: inertness facing titanium alloys and suitable/enough thermal-shock resistance. Until now, yttrium and calcium oxides were those materials that performed best on what concerns to thermodynamic stability. However, in both cases, crucibles thermal-shock resistance was very poor, and there are references to crucibles that cracked during melting. Besides, calcium oxide reveals manipulation problems, due to its high higroscopicity. This paper concerns to the evaluation of zircon based crucibles with Y2O3 inner layer for induction melting of TiAl based alloys. A novel multi layered crucible production technique based in a centrifugally assisted slip casting process followed by a sintering operation is described, and results concerning to crucibles porosity and wall composition and morphology are presented. Crucibles obtained in different processing conditions were used to melt a Ti48Al alloy which was poured in graphite moulds. Experimental results include alloy chemical contamination with residual elements, mainly yttrium and oxygen, microhardness measurement and the presence of yttrium oxide and zircon inclusions in the cast samples. Results concerning to the crucibles behaviour are also presented with particular attention to cracks development. The Y2O3 crucible layer was found to suffer some erosion and be slightly dissolved by the molten alloy and the extent of those phenomena depends on the porosity of the layer surface, for fixed experimental melting conditions.

Download Full-text

Effects of metallurgical factors on reticular crack formations in Nb-bearing pipeline steel

High Temperature Materials and Processes ◽

10.1515/htmp-2020-0043 ◽

2020 ◽

Vol 39 (1) ◽

pp. 81-87 ◽

Cited By ~ 1

Author(s):

Hangyu Zhu ◽

Lanqing Wang ◽

Jianli Li ◽

Jixuan Zhao ◽

Yue Yu

Keyword(s):

Iron Oxide ◽

Continuous Casting ◽

Pipeline Steel ◽

Solidification Process ◽

Casting Process ◽

Chemical Compositions ◽

Steel Matrix ◽

Continuous Casting Process ◽

Residual Elements ◽

Crack Susceptibility

AbstractMicroscopic morphologies of reticular cracks in Nb-bearing pipeline surfaces are shown in this work. A decarburization layer, oxidized round spots, and the distributions of residual elements are each detected to better understand the mechanisms of reticular crack formations. The results show that reticular cracks are discontinuously distributed and filled with iron oxide. The oxidized round spots near the crack sides are larger and more intensive than steel matrix, with primary chemical compositions of Fe, Mn, and Si oxides. There is no obvious enrichment of Cu, Cr, or Sn near the crack zones. The formation of reticular cracks occurs prior to both decarburization and the formation of oxidized round spots. The ferrite potential (FP) of the examined pipeline steel is 1.05, which leads to a higher relative crack susceptibility. It is concluded that reticular cracks are generated during the continuous casting solidification process due to the extension of intergranular microcracks along grain boundaries under the abnormal conditions of the continuous casting process.

Download Full-text

Analysis of Water Consumption Intensity for Steel Production in China

Materials Science Forum ◽

10.4028/www.scientific.net/msf.993.1465 ◽

2020 ◽

Vol 993 ◽

pp. 1465-1472

Author(s):

An Long Li ◽

Zhi Hong Wang ◽

Bo Xue Sun ◽

Si Wen Gao

Keyword(s):

Continuous Casting ◽

Water Consumption ◽

Steel Production ◽

Casting Process ◽

Balance Model ◽

Total Water ◽

Steel Rolling ◽

Total Water Consumption ◽

Accounting Model ◽

Consumption Intensity

The water consumption intensity of steel production through BF-BOF technology was decomposed by an innovative process-based water-accounting model, i.e., water-balance model. One ton of steel product was chosen to be the functional unit. The system boundary of the case study included the production processes of coking, sintering, iron making, steel making, continuous casting and rolling. The results showed that the water consumption intensity of steel production was 3.969t/t in this case. The water consumption of evaporation, solidification and wastewater were 2.373t, 0.013t and 1.583t, accounting for 59.79%, 0.33% and 39.88% of the total water consumption, respectively. Steel rolling is the largest contributor to water consumption, and the amount of water consumption is 1.523t, accounting for 38.37% of the total water consumption; followed by coking process and continuous casting process, the amounts of which are 0.814t (20.50%) and 0.634t (15.97%), respectively. This finding can push the utilization of advanced technologies to save water resource in steel industry.

Download Full-text

Monitoring Surface Defects Deformations and Displacements in Hot Steel Using Magnetic Induction Tomography

Sensors ◽

10.3390/s19133005 ◽

2019 ◽

Vol 19 (13) ◽

pp. 3005 ◽

Cited By ~ 2

Author(s):

Fang Li ◽

Stefano Spagnul ◽

Victor Odedo ◽

Manuchehr Soleimani

Keyword(s):

Continuous Casting ◽

Magnetic Induction ◽

Surface Defects ◽

Surface Deformation ◽

Real Life ◽

Steel Production ◽

Casting Process ◽

Contactless Method ◽

Image Region ◽

Magnetic Induction Tomography

Magnetic Induction Tomography (MIT) is a non-invasive imaging technique that has been widely applied for imaging materials with high electrical conductivity contrasts. Steel production is among an increasing number of applications that require a contactless method for monitoring the casting process due to the high temperature of hot steel. In this paper, an MIT technique is proposed for detecting defects and deformations in the external surfaces of metal, which has the potential to be used to monitor the external surface of hot steel during the continuous casting process. The Total Variation (TV) reconstruction algorithm was developed to image the conductivity distributions. Nonetheless, the reconstructed image of the deformed square metal obtained using the TV algorithm directly does not yield resonable images of the surface deformation. However, differential images obtained by subtracting the image of a perfect square metal with no deformations from the image obtained for a deformed square metal does provide accurate and repeatable deformation information. It is possible to obtain a more precise image of surface deformation by thresholding the differential image. This TV-based threshold-differencing method has been analysed and verified from both simulation and experimental tests. The simulation results reported that 0.92 % of the image region can be detected, and the experimental results indicated a 0.57 % detectability. Use of the proposed method was demonstareted in a MIT device which was used in continuous casting set up. The paper shows results from computer simulation, lab based cold tests, and real life data from continoeus cating demonstating the effectiveness of the proposed method.

Download Full-text

Study and Design on Clean Steel Production Platform

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.161.37 ◽

2012 ◽

Vol 161 ◽

pp. 37-41

Author(s):

Fu Ming Zhang

Keyword(s):

Continuous Casting ◽

High Efficiency ◽

Low Cost ◽

Steel Production ◽

Casting Process ◽

Steel Plant ◽

Continuous Casting Process ◽

High Quality ◽

Iron And Steel ◽

Clean Steel

The technology for clean steel production in modern steel plant is analyzed, a philosophy with production efficiency, manufacturing cost and product performance in its core. A review on functions is also made which of high-efficiency, low-cost and high-quality steel products manufactured by the new generation iron and steel plant, in combination with the study on design of steelmaking – continuous casting process of Shougang Jingtang iron and steel plant. By applying precise and dynamic design system to optimize and allocate systems and working procedures of hot metal pretreatment, converter smelting, secondary refining, continuous casting process, etc, a platform of high-efficiency, low-cost and high-quality clean steel production is built.

Download Full-text