Beam Blanks Research Articles

Fracture resistance of the deposited metal under dynamic and cyclic loading

Analyses of experimental data are presented that enable the fracture resistance assessment of dynamically and cyclically loaded materials used for the manufacture and surfacing of rollers in continuous casting machines for beam blanks and crimping mill rollers. It has been noted that steels for manufacturing and surfacing of crimping rolls with different carbon content and alloying elements, differ in the determination fraction of the crack nucleation work in the integral value of the impact strength. The value of that fraction is much higher for corrosion-resistant steels of the Cr13 type which are also distinguished by high fracture resistance to cyclic loading. It is shown that the properties of these steels make it possible, along with the use of CCM rollers for surfacing, to recommend them for hardening the rollers in crimping mills. The possibility of an additional increase in the efficiency of the crimping rolls by eliminating uneven wear along the length of the barrel by surfacing a layer of Cr13 steel with a variable carbon content (0.10-0.25 %) is considered.

Simulation of BB-2 beam billet conti-nuous casting for production of large-sized I-beams

In connection with expansion of construction sector, it is planned to develop 80‒90‒100 I-beams. For these I-beams, universal section of continuously cast billet BB-2 (1050×450×120) was developed. The purpose of this work was to check casting parameters of given billet in a simulation model, using LVMFlow software, to confirm analytical calculations. Following parameters were chosen as parameters to be evaluated: geometric shape of the cast billet, temperature and dynamic parameters of casting. For maximum reliability, boundary conditions were set similar to real parameters of the CCM-3 at EVRAZ NTMK JSC, however, as assumptions, the calculation was carried out only in zone of direct contact with mold sleeve, and plane deformation condition was set along casting. Simulation results showed possibility of using LVMFlow to simulate the beam blanks casting processes with high degree of convergence. Casting BB-2 billet is technically possible in the conditions of continuous caster No. 3 at JSC EVRAZ NTMK, when the mold is replaced. Hydrodynamic pressure is created only on walls of crystallizer; there is vacuum on remaining surfaces due to lack of crystallizer walls narrowing sleeve towards cooling. Crystallization occurs most slowly along the interface between the wall and the BB flanges, however, there are no defects in the form of splashes, due to the low hydrodynamic pressure in these zones

Simulation of BB-2 beam billet conti-nuous casting for production of large-sized I-beams

In connection with expansion of construction sector, it is planned to develop 80‒90‒100 I-beams. For these I-beams, universal section of continuously cast billet BB-2 (1050×450×120) was developed. The purpose of this work was to check casting parameters of given billet in a simulation model, using LVMFlow software, to confirm analytical calculations. Following parameters were chosen as parameters to be evaluated: geometric shape of the cast billet, temperature and dynamic parameters of casting. For maximum reliability, boundary conditions were set similar to real parameters of the CCM-3 at EVRAZ NTMK JSC, however, as assumptions, the calculation was carried out only in zone of direct contact with mold sleeve, and plane deformation condition was set along casting. Simulation results showed possibility of using LVMFlow to simulate the beam blanks casting processes with high degree of convergence. Casting BB-2 billet is technically possible in the conditions of continuous caster No. 3 at JSC EVRAZ NTMK, when the mold is replaced. Hydrodynamic pressure is created only on walls of crystallizer; there is vacuum on remaining surfaces due to lack of crystallizer walls narrowing sleeve towards cooling. Crystallization occurs most slowly along the interface between the wall and the BB flanges, however, there are no defects in the form of splashes, due to the low hydrodynamic pressure in these zones

Comparative analysis of the thermal behavior of blooms and beam-blanks during continuous casting: Development and validation of a mathematical model for heat transfer

The present work explores the feasibility of producing blooms and beam blanks in a continuous casting machine using a single support rollers setup, aiming to eliminate the need for specialized setups for each geometry. The current practice requires frequent roll replacements during production switches, leading to reduced machine availability and safety risks.To assess the viability of the new approach, a 2D mathematical model for heat transfer and solidification was developed for both blooms and beam blanks. Simulations with the current and the new setup were performed, and their results analyzed. The model was validated with experiments during production campaigns at the steel melting shop. The model accurately predicts the casting process, with solid fraction deviation of 6% for blooms and 16% for beam blanks, and temperature difference between the model and thermal imaging measures values are between 20 °C and 70 °C.The heat transfer simulation results show that a single rollers setup can yield minimal variations in the temperature related operational parameters, supporting the feasibility of this approach. In addition to the thermal analysis performed in this work, mechanical stress and strain assessments need to be performed to further investigate the suggested solution and they will be the topic of future works.The findings provide valuable insights for the steel industry, as this type of feasibility study is a relatively unexplored area. Furthermore, the models developed can also be used to optimize process parameters, study defects formation during continuous casting and in the development of new products.

Mathematical modelling of the continuous casting of blooms and beam blanks

Mathematical modelling of the continuous casting of blooms and beam blanks

Effect of submerged entry nozzle structure on fluid flow in a beam blank continuous casting mould

ABSTRACT Fluid flow is of great importance to the quality of near-net-shape beam blanks. Particle image velocimetry (PIV) was employed to measure the fluid flow inside a full-scale water model for a beam blank continuous casting mould from five sections under the different submerged entry nozzles (SENs) in the present work. The results show that the jet flow under the single-port SEN leads to a too significant impact on the solidifying shell in the region of the flange-centre and the fillets, especially the fillet of the outer arc. The resultant horizontal velocities under the three-port SENs are much larger than those at the single-port SEN and can easily lead to the entrapment of mould slag due to excessive shear force. The four-port SEN with the included angle of 140° and inclination angle of 12° is suitable for promoting uniform growth of the solidifying shell, mould powder melting, and inclusion removal.

Reducing Surface Cracks and Improving Cleanliness of H-Beam Blanks in Continuous Casting — Improving continuous casting of H-beam blanks

AbstractA beam blank is ideal for H-beam production, but there are more defects in/on beam blanks than other common blanks. The study of the H-beam blank quality assurance system has great significance for production to determine the key factors causing defects and optimise the casting process parameters. Experimental analysis and numerical simulation, based on an actual production process, were used as research methods. The former was used to test and analyse the cracks, inclusions, and the flux in the mould to determine the preliminary factors causing defects in a beam blank. The latter was used to simulate the flow and temperature fields and the movement of inclusions to determine the key factor leading to defects and to optimize the casting process parameters. Online implementation of the recommendations of this project was developed, which proved that it is very useful and efficient to control surface cracks on the web and enhance cleanliness of an H-beam blank.

Simulation of Crack Initiation and Propagation in the Crystals of a Beam Blank

Surface cracking seriously affects the quality of beam blanks in continuous casting. To study the mechanism of surface crack initiation and propagation under beam blank mesoscopic condition, this study established a polycrystalline model using MATLAB. Based on mesoscopic damage mechanics, a full implicit stress iterative algorithm was used to simulate the crack propagation and the stress and strain of pores and inclusions of the polycrystalline model using ABAQUS software. The results show that the stress at the crystal boundary is much higher than that in the crystal, cracks occur earlier in the former than in the latter, and cracks extend along the direction perpendicular to the force. When a polycrystalline model with pores is subjected to tensile stress, a stress concentration occurs when the end of the pores is perpendicular to the stress direction, and the propagation and aggregation direction of the pores is basically perpendicular to the direction of the tensile stress. When a polycrystalline model with impurities is subjected to force, the stress concentrates around the impurity but the strain here is minimal, which leads to the crack propagating along the impurity direction. This study can provide theoretical guidance for controlling the generation of macroscopic cracks in beam blanks.

Initiation of Surface Cracks on Beam Blank in the Mold during Continuous Casting

Surface cracking seriously affects the quality of beam blanks, a relatively new blank in the continuous casting in China. In order to study the mechanism of the initiation and propagation of surface cracks, this study established a 2D micro-segmented model of the solidification process for a beam blank in the mold, with a user subroutine DFLUX written in Fortran. Using a contact algorithm, the stress in the shell of the beam was analyzed considering the mechanical properties of the material (Q235B), thermal stress, surface friction force and ferrostatic pressure. The results showed that at the center of the web, surface longitudinal cracks were most likely to initiate at a height of 180 mm from the meniscus; at the fillet, surface longitudinal cracks were most likely to initiate at a height of 200 mm from the meniscus. Moreover, the casting speed showed a greater effect on surface crack initiation than the pouring temperature did. This study reveals the cause of longitudinal crack initiation, and the most likely positions of cracks on the strand. Thus, it is instructive for controlling surface cracks in production.

Propagation of surface cracks on beam blank in the mould during continuous casting

ABSTRACTWe focus on crack propagation to investigate surface cracks in the mould during continuous casting, based on the crack initiation mechanism proposed in previous studies. The temperature and stress data of a solidified shell were extracted, and an extended finite element model based on the continuous damage theory of elastic–plastic materials was developed to simulate surface crack propagation. The results showed that, in the cracked area, stress concentration occurred at the crack tip, and the element split open and the crack propagated when the maximum principal stress in the stress concentration area reached the critical value. Prefabricated cracks in the fillet and web mainly developed into longitudinal cracks in the mould. The theoretical mechanism of this study was found to be the same as the crack propagation mechanism observed during the actual production of beam blanks. Thus, this study reveals the theoretical principle of crack initiation and propagation and can provide theoretical guidance for controlling surface cracks during beam blank continuous casting.

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

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.

Two-dimensional heat transfer model for secondary cooling of continuously cast beam blanks

A two-dimensional heat transfer model was developed for the secondary cooling system during beam blank continuous casting. The finite element method was used to calculate the heat transfer. Accurate cooling boundary conditions in the secondary cooling zone are involved, including spray water cooling, water evaporation cooling, radiation cooling and roll contact cooling in the casting direction and non-uniform distribution of spray water flow density in the cross-section. The causes of longitudinal crack at the fillet during Q235 steel continuous casting were analysed on the basis of the simulation of the developed model, and then the spray water flow and the transverse nozzle layout were optimised. Practical results show that the surface quality of the beam blank improved after optimisations. Numerical results from the present model were validated using previous experimental measurements, which show good agreement.

Trends in Steelmaking 2012

About 60 % of the crude steel in Europe is currently produced by the oxygen steelmaking process and 40 % by the electric steelmaking process. The product range is of decisive importance for the layout of the steelworks and the equipment for secondary metallurgical treatment. Regarding steelmaking worldwide, thin slabs are increasingly being produced in addition to conventional formats such as slabs, blooms, billets and beam blanks. In order to ensure long-term economic success, however, companies have continuously to develop sophisticated technologies for steel production. Challenges for the future remain in the production of high-purity steel grades, as well as the development of zero-error strategies with maximum productivity and flexibility. This paper summarizes current trends in the development of steelmaking processes.

Study of Micro-Inclusion of Beam Blanks

According to the three kinds of MRT3-BA steel technological processes, which include BOF→LF→CC, BOF→RH→CC and BOF→LF→RH→CC, some systematic analysis are introduced to research on the contents of T[O] and [N], and the type, composition and quantity of micro-inclusions in the three processes. The level of cleanliness in billet will also be systematic analysed in comparative. The results of the study show that the contents of T[O] respectively are 20.8×10-6, 14.3×10-6 and 13×10-6 in billet of Process 1, Process 2, Process 3. Through the comparison with production data of other manufacturers, control of T[O] has reached a high level in MRT3-BA deep punching steel. The numbers of micro-inclusions respectively are 6.8/mm2, 5.66/mm2 and 5.36/mm2 in billet; the control level in MRT3-BA steel has reached domestic advanced level. Taken steel cleanliness and production cost into account, the better technological process of MRT3-BA stamping steel is BOF→RH→CC.

Thermal behaviour of moulds with different water channels and their influence on quality in continuous casting of beam blanks

Two-dimensional finite element heat transfer models have been developed to predict temperature distribution in beam blank moulds with large and small hole water cooling channels. The effects of water channel design and grinding thickness on transverse temperature profile in meniscus region were analysed in detail. The effects of both moulds during plant trials are also compared. The results show that the peak temperature is found in the fillet area of the large hole mould and is 20°C higher than that of the small hole mould. With increasing grinding thickness, peak temperature in both moulds decreases linearly, and when the grinding thickness reaches 9 mm, the peak temperature of the small hole mould exceeds that of the large hole mould. The transverse temperature uniformity of the hole mould is superior to that of the large hole mould. It is also found that longer mould life, better strand surface quality and more homogeneous surface microstructure are obtained when using the small hole mould.

Nucor Corp.

AbstractMetal Works (MIC: SIC: 3312 NAIC: 331111)Nucor produces and sells steel and steel products via its steel mills and steel products segments. Co.'s steel mills segment produces hot‐rolled steel (angles, rounds, flats, channels, sheet, beams, pilings, blooms, beam blanks and plate) and cold‐rolled steel, while its steel products segment produces steel joists and joist girders, steel deck, cold finish steel, steel fasteners, metal building systems, light gauge steel framing, steel grating and expanded metal, and wire mesh. In the U.S., Co.'s hot‐ and cold‐rolled steel are sold to steel service centers, fabricators and manufacturers, while its steel joists, joist girders and steel deck are sold to general contractors and fabricators.

Nucor Corp.

AbstractMetal Works (MIC: SIC: 3312 NAIC: 331111)Nucor produces and sells steel and steel products via its steel mills and steel products segments. Co.'s steel mills segment produces hot‐rolled steel (angles, rounds, flats, channels, sheet, beams, pilings, blooms, beam blanks and plate) and cold‐rolled steel, while its steel products segment produces steel joists and joist girders, steel deck, cold finish steel, steel fasteners, metal building systems, light gauge steel framing, steel grating and expanded metal, and wire and wire mesh. Co. sells hot‐ and cold‐rolled steel to steel service centers, fabricators and manufacturers, as well as steel joists/ joist girders and steel deck to general contractors and fabricators in the U.S.

Nucor Corp.

AbstractMetal Works (MIC: 11.3 SIC: 3312 NAIC: 331111)Nucor produces and sells steel and steel products via its steel mills and steel products segments. Co.'s steel mills segment produces hot‐rolled steel (angles, rounds, flats, channels, rebar, sheet, beams, pilings, billets, blooms, beam blanks and plate)and cold‐rolled steel, while its steel products segment produces steel joists and joist girders, steel deck, cold finished steel, steel fasteners, metal building systems, light gauge steel framing, and wire and wire mesh. In the U.S., Co. sells hot‐ and cold‐rolled steel to steel service centers, fabricators and manufacturers, and sells steel joists/joist girders and steel deck to general contractors and fabricators.

Nucor Corp.

AbstractMetal Works (MIC: 11.3 SIC: 3312 NAIC: 331111)Nucor produces and sells steel and steel products via two business segments: steel mills and steel products. Co.'s key products from the steel mills segment are hot‐rolled steel (angles, rounds, flats, channels, rebar, sheet, wide‐flange beams, pilings, billets, blooms, beam blanks and plate) and cold‐rolled steel, while its steel products segment produces steel joists and joist girders, steel deck, cold finished steel, steel fasteners, metal building systems and light gauge steel framing. In the U.S., Co. sells hot‐ and cold‐rolled steel to steel service centers, fabricators and manufacturers, and it sells steel joists/joist girders and steel deck to general contractors and fabricators.

Nucor Corp.

AbstractMetal Works (MIC: 11.3 SIC: 3312 NAIC: 331111)Nucor produces and sells steel and steel products via two business segments: steel mills and steel products. Co.'s key products from the steel mills segment are hot‐rolled steel (angles, rounds, flats, channels, rebar, sheet, wide‐flange beams, pilings, billets, blooms, beam blanks and plate) and cold‐rolled steel, while its steel products segment produces steel joists and joist girders, steel deck, cold finished steel, steel fasteners, metal building systems and light gauge steel framing. In the U.S., Co. sells hot‐ and cold‐rolled steel to steel service centers, fabricators and manufacturers, and it sells steel joists/joist girders and steel deck to general contractors and fabricators.