Continuous Casting Parameters Research Articles

Optimization of Macro Segregation and Equiaxed Zone in High-Carbon Steel Use in Prestressed Concrete Wire and Cord Wire Application

In this study, the relationship between macro segregation and the equiaxed zone in high-carbon grades with continuous casting parameters was investigated and optimized at the İsdemir iron and steel plant. The work was conducted for the 1080 quality of the SAE J403 standard. In this study, some parameters, such as casting speed, secondary cooling, EMS current value and EMS frequency value, were examined. When the results of the experiments are examined, it can be observed that the equiaxed zone in the macrostructure decreases significantly with the reduction of the EMS frequency value. The decrease in casting speed and increase in EMS current value caused an increase in the equiaxed zone. The increment in secondary cooling led to a decline in the equiaxed zone. Once the macro segregation results are examined, it can be seen that it is very important to optimize the continuous casting parameters in order to reduce the macro segregation results of—especially—carbon, sulfur and phosphorus elements. It has also been determined that the macro segregation values of carbon, sulfur and phosphorus elements are low in casting conditions where casting speed is low, and the EMS current value and EMS frequency value are high. In addition, macro segregation measurements of manganese, silicon, chromium and vanadium elements are found to be low under similar casting conditions. It is critical to optimize the continuous casting parameters before production, especially in high-carbon grades to be used for prestressed concrete wire and cord wire applications. As a result of the work conducted using the İsdemir billet continuous casting machine for the 1080-grade SAE J403 standard, aiming to optimize macro segregation and the equiaxed zone, the effective results have been achieved by using process parameters of 2.8 m/min casting speed, 360 A EMS current, 5 Hz EMS frequency and low secondary cooling intensity.

Real-time prediction and adaptive adjustment of continuous casting based on deep learning

Digitalisation of metallurgical manufacturing, especially technological continuous casting using numerical models of heat and mass transfer and subsequent solidification has been developed to achieve high manufacturing efficiency with minimum defects and hence low scrappage. It is still challenging to perform adaptive closed-loop process adjustment using high-fidelity computation in real-time. To address this challenge, surrogate models are a good option to replace the high-fidelity model, with acceptable accuracy and less computational time and cost. Based on deep learning technology, here we developed a real-time prediction (ReP) model to predict the three-dimensional (3D) temperature field distribution in continuous casting on millisecond timescale, with mean absolute error (MAE) of 4.19 K and mean absolute percent error (MAPE) of 0.49% on test data. Moreover, by combining the ReP model with machine learning technology—Bayesian optimisation, we realised the rapid decision-making intelligent adaptation of the operating parameters for continuous casting with high predictive capability. This innovative and reliable method has a great potential in the intelligent control of the metallurgical manufacturing process.

Effect of Steel Inclusion on Heat Treatment Quench Crack - Case Study

Hypoid pinion is a major member in the heavy truck axle as it transmits the power from propeller shaft to hypoid ring gear. This is the first member in axle assembly to receive the power from transmission. Metallurgical quality is inevitable parameter in this part. In this case, a fracture analysis of hypoid pinion carried out, root cause is found & corrections are addressed. The quench crack is generated during the case carburizing treatment. The fractography shows that this crack is initiated from the gross non-metallic inclusion present at the sub surface of the drive pinion. SEM EDS analysis conducted & identified inclusion as Aluminium Oxide predominantly with a dimension 7 mm in length & 1mm in width caused the longitudinal crack on the pinion. The ishikawa diagram plotted for steel mill process to understand the cause. Since the type of inclusion is Al2O3, focused more on ladle refining station, VD process & continuous casting parameters in steel mill process where entrapment could occur. The appropriate corrective action taken in steel mill on VD process, post VD soft rinse, multiple sampling for inclusion from first & last billet, NDT method UT phased array system is introduced by developing the master sample having size same as inclusion. The Inclusion went undetected whole the process starting from steel mill to pinion case carburizing heat treatment & is opened up after quenching due to volumetric difference in crystal, happens during heating & cooling. The mechanism of crack generation is discussed which involves crystallographic changes takes place during carburizing cycles.

Increasing Casting Speed in High Carbon and Micro Alloy DIN EN ISO 16120-2: 2011-C66D Steels

Different parameters can be used together in the continuous casting process known as an important steel production stage in the world. It is important to use metallurgical appropriate parameters to meet the product properties. Many innovations have been made in the continuous casting process from past to present. It is known that studies are carried out on many effective topics such as steel analysis, refractory materials, continuous casting parameters, in order to make the proper solidification that will meet the needs with its continuous casting capabilities. When continuous casting parameters are examined; the casting speed parameter was found to be effective in terms of quality needs in macro samples. Therefore, in this study, the effect of the increase of casting speed parameters on the quality of macro samples was investigated. As a method; in high carbon, micro-alloyed DIN EN ISO 16120-2: 2011-C66D quality steels, in different castings, this parameter was changed and macro samples were taken and evaluated in terms of quality needs. When macro sample quality results are compared; the effect of casting speed was observed. In this study; the effect of the increase in casting speed in continuous billet casting facility on optimum metallographic and physical quality has been investigated and the results have been interpreted.

Optimization of the Gap Parameters of Supporting Rollers of Curvilinear Continuous Casting Machine

A study was performed to determine the influence of technological and design parameters of continuous casting of steel on reducing the thickness of the billet along the technological line of a curvilinear continuous casting machine (CCM) designed by Uralmashzavod OJSC. The effect of carbon content and casting speed on linear shrinkage through the billet’s thickness was investigated. It was established that in all cases there was a discrepancy between the thickness of the billet and the settings used for CCM rollers. This discrepancy can lead to defects in the billet caused by the distortion of its shape (owing to the blow-up under the action of ferrostatic pressure) and to an increase in friction and, accordingly, pulling forces. On the basis of the obtained results, new settings for the rollers on the hard and hydraulic sections were proposed. The use of recommended parameters considerably reduces the discrepancy between the thickness of the billet and the gap of the rollers, which will improve product quality.

Investigation of Microstructure of Oxygen-Containing Copper

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Application of Numerical Model of Continuous Cast Bloom Crystallization to Improve the Efficiency of Mechanical Soft Reduction Technology

The paper presents the results of the analysis of thermal state of continuous cast bloom on the stage of incomplete crystallization in the area of possible places of application of technology of Mechanical Soft Reduction (MSR), received during simulation on mathematical model, which was implemented in the software package using the finite element method. For the conditions of continuous cast bloom with a cross section of 360-400 mm, we studied the characteristics of temperature change over the cross section of the bloom, the growth dynamics of the solid shell, the number of the solidified component, and the end point position of solidification depending on the technological parameters for continuous casting of A516, 5140 1070 and AISI steel brands. The obtained data on the thickness of the crystallized shell of continuous cast bloom and the amount of solid phase depending on the casting speed and steel grade allowed us to conclude about the possible place of installation of the MSR unit. The results of mathematical simulation can be transferred in a digital form to the strength model of deformation of continuous cast bloom at the stage of incomplete crystallization.

Measurement of Molten Steel Velocity near the Surface and Modeling for Transient Fluid Flow in the Continuous Casting Mold

In the current work, a rod deflection method (RDM) is conducted to measure the velocity of molten steel near the surface in continuous casting (CC) mold. With the experimental measurement, the flow velocity and direction of molten steel can be obtained. In addition, a mathematical model combining the computational fluid dynamics (CFD) and discrete phase method (DPM) has been developed to calculate the transient flow field in a CC mold. The simulation results are compared and validated with the plant measurement results. Reasonable agreements between the measured and simulated results are obtained, both in the trends and magnitudes for the flow velocities of molten steel near the mold surface. Based on the measured and calculated results, the velocity of molten steel near the surface in the mold increases with increasing casting speed and the casting speed can change the flow pattern in the mold. Furthermore, three different types of flow patterns of molten steel in the mold can be obtained. The pattern A is the single-roll-flow (SRF) and the pattern C is the double-roll-flow (DRF). The pattern B is a transition state between DRF and SRF, which is neither cause the vortices nor excessive surface velocity on the meniscus, so the slag entrainment rarely occurs. Argon gas injection can slow down the molten steel velocity and uplift the jet zone, due to the buoyancy of bubbles. Combination of the measurement and numerical simulation is an effective tool to investigate the transient flow behavior in the CC mold and optimize the actual operation parameters of continuous casting to avoid the surface defects of the automobile outer panels.

Processing parameter optimization for continuous casting of 38CrMoAl round bloom based on a prediction model of the equiaxed crystal ratio

ABSTRACTTo control the quality of the continuous casting of 38CrMoAl round bloom, a prediction model combining the criteria of columnar to equiaxed transition, the numerical simulation of heat transfer and measured data is proposed. In this model, the inaccurate selection of heterogeneous nucleation density can be avoided. The accuracy of the numerical simulation is verified by a nail-shooting experiment, and the effects of parameters on equiaxed crystal ratio (ECR) were studied. It is proposed that low superheat and weak secondary cooling intensity increase ECR, while casting speed has little effect on ECR. The effect of strand electromagnetic stirring on the increasing ECR is clear, and it is more effective than superheat in the increasing ECR. When the diameter of the round bloom increases from 500 to 600 mm, the Cet increases from to , where ECR is larger. The suitable continuous casting parameters of ϕ500 mm bloom include a superheat of 30°C and a continuous casting speed of 0.19 m/min, as well as a weak secondary cooling intensity.

电工用铜铜线坯连铸过程凝固结晶研究

本文主要研究连铸过程中冷却强度、连铸温度及连铸速度对电工用铜线坯连铸组织的影响，通过合理布置结晶轮冷却系统及确定合适的连铸温度和速度，最终得到呈中心对称的柱状晶穿晶组织铸坯，满足电工用铜线坯的性能要求。 This paper mainly researches the effect of continuous casting parameters on copper microstructure, including cooling intensity, casting temperature and speed. Through the reasonable arrangement of crystallization cooling system and appropriate casting temperature and speed, in the end, the center symmetric columnar crystals are formed in the billet to satisfy the requirement of the copper drawing stock for electrical performance.

Causes of High Temperature Ductility Trough of Microalloyed Steels

Influence of continuous casting parameters and hot rolling regimes on the hot ductility in microalloyed pipeline steels and structural steels has been investigated using Gleeble 3800 system. Dependence of the hot ductility on temperature for different thermomechanical treatment conditions has been studied by physical simulation. The high temperature ductility drop occurs close to the phase and magnetic transition temperature for all the studied schedules. The elastic modulus at this temperature abnormally increases. The main reason of the ductility decrease is the elastic modulus increase. The structural factors (e.g. non-metallic inclusions on initial grain boundaries, interstitial impurities, grain size) lead to the additional decrease of the ductility. Increase of the grain boundary lengths and steel refining lead to the hot ductility improvement. The ductility trough disappears after the deformation of metal in austenitic region to decrease the austenite grain size significantly.

CONTINUOUS CASTING AND DEFORMATION INSTALLATION FOR THE PRODUCTION OF STEEL PLATES FOR WELDED PIPES. REPORT 2

Technological feasibility of combined process and installation of continuous casting and deformation to obtain high mechanical properties and fine-grained structure of steel sheets for weld pipes are considered. The problem of metal stress-strain state under solidified metal cobbing by the die walls of assembly mold is stated taking into account a force of the liquid phase pulling from the permanent crystallizer of installation. Parameters of cyclic deformation focus for thin slab sheets production, initial data for design and boundary conditions of the problem are given. A design scheme for determining stress-strain state of metal in circular deformation focusis presented. Results are obtained by solving the problem of continuum mechanics by finite element method: flat statement of contact problem of elastic-plasticity was used in conditions of large deformations and displacements.ANSYS software was used to solve the problem. The calculation results are presented in form of stress diagrams along the strip symmetry axis and on part of contact line of deformation focus with the die wall. Regularities of distribution of tangential stresses on contact surface of circular deformation focus are presented. Evaluation of solidified metal flow on the boundary with liquid phase during solidified metal cobbing by die walls is provided taking into account a force of liquid phase pulling from permanent crystallizer. The estimation of stress state scheme of metal in circular deformation focus during thin slab cobbing with a high degree of deformation is described in order to improve quality of steel sheets for weld pipes production. The main parameters of continuous casting and deformation plant for weld pipes steel sheets production are given.

Effects of micro-alloying elements and continuous casting parameters on reducing segregation in continuously cast slab

In this work, CAFE model and SDAS model were established to study the macrostructure and secondary dendrites of slab cross-section, respectively. The influences of micro-alloying elements (Nb, V, and Ti), superheat, and casting speed on secondary dendrite arm spacing (SDAS) were investigated. The results revealed that within the adjustable range of micro-alloying elements, the increase of Nb and V contents in steel can contribute to refining SDAS. The value of average SDAS with the increase of Ti content had a big fluctuation. The variation of SDAS attributed to the influence of micro-alloying elements on the thermal conductivity which further resulted in the change of effective solidification time (EST). EST played a leading role in determining SDAS. The decrease of superheat or casting speed can contribute to refining SDAS. The influence ratios of micro-alloying elements on SDAS were larger than that of superheat and casting speed. After adjusting the micro-alloying elements contents and CC process parameters, the SDAS in the experimental slab obtained effective refinement and the center equiaxed crystal ratio of slab cross-section increased by 8.5%. The segregation defect in the center of experimental slab got improved as well.

Quality enhancement of continuous cast slabs by predicting segregation defects

Relations between continuous casting parameters and quality of continuous cast slabs are established. A model for predicting slab quality is developed. On that basis, a new casting technology is proposed; its distinguishing feature is that consumable cooling blocks are introduced into the mold to suppress internal defects.

Correlation between the continuous casting parameters and secondary dendrite arm spacing in the mold region

In this article, a mathematical model for cooling rate (CR) in the mushy zone based on the local heat flux density in the mold region was introduced. This model takes into account the parameters of continuous casting in the mold region such as mold level (ML), mold frequency (s), mold thickness (dm), flow rate of cooling water (Q), casting velocity (VC) and viscosity of the mold powder (η). This model was applied to estimate secondary dendrite arm spacing (SDAS) by the analytical model of Thomas–Won. Comparison between the measured and calculated SDAS confirmed the model validity. The results revealed that, increasing VC, Q, fs and η, leads to decreasing the SDAS, increasing the dm increases the SDAS and ML no affect the SDAS. Also, the most effect is related to the viscosity of the mold powder.

Continuous casting of billets made of a chromium-nickel titanium-containing corrosion-resistant steel

The continuous casting of a corrosion-resistant titanium-alloyed steel into billets is considered. Approaches to optimizing the chemical composition of the metal and the parameters of continuous casting are proposed to increase the quality of a continuously cast billet and the related rolled products.

Research on Thermocouple Embedded Position for CC Mould Copper Plate with Different Cooing Water Temperature

Cooling water temperature is one of the key parameters for continuous casting, and it has great influence to the thermal state of the mould copper plate. The coupled visco-elasto-plastic FEM models have been presented for thermal process analysis of steel the mould copper plates. With the understanding to the mould thermal state for different heat transfer coefficient, the characters of mould copper plate thermal state is obtained. It is shown that, when the cooling water temperature increasing, the surface temperature of the mould plate would be higher, but the temperature distribution trend is steady, and at same time, the cooling water temperature has little influence to the equivalent strain distribution, especially for the nodes nearer to the meniscus. Lower cooling water temperature would cause bigger mould copper plate equivalent strain, and induce more surface crack of the strand. For breakout signal catching of this mould, the thermocouple is better to embedded lower than 350mm to the meniscus by vertical, and less than 30mm to the mould cold side by level.

The Effect of Temperature Fluctuation on the Formation of Billet Surface Defect in the Initial Solidification Area

The heat transfer in steel continuous casting process under mold oscillation was calculated, and temperature fluctuation phenomena was found in the initial solidification area, the maximum value was approximate 16 °C. The effect of different continuous casting parameters on temperature fluctuation were analyzed, and the temperature fluctuation was considered to be a key factor to the formation of oscillation marks. The Index of Temperature Fluctuation(ITF) was proposed to predict the effect of temperature fluctuation on the formation of billet surface defects.

Optimisation of continuous casting process parameters based on coupled heat and stress model

Based on a coupled heat and stress model, an artificial intelligence optimisation program was developed to optimise the process parameters in the continuous casting of steel. The program can be used to identify the key factors for the cracks of the strand and obtain the optimum process parameters of continuous casting. The optimisation program contains two models, one is the thermomechanical model developed using the finite difference method, and the other is the optimisation model developed using the subproblem approximation method. The whole program works by automatic iteration between the two models. This study has taken the stress constraint in the solidified shell into consideration when studying the metallurgical constraints. The application of the achieved optimum parameters would make it possible to run the caster at maximum productivity, with minimum cost and fewer defects. After manufacturing verification of this optimisation project, the incidence of cracks has reduced from 8% to 2%, and water consumption in the secondary cooling zone has been decreased by 25%.

Effect of soft reduction on the structure of continuously-cast slabs

A technique has been developed for computer prediction of the soft-rolling-related reduction in the axial chemical inhomogeneity of a continuous-cast steel billet. The resulting computer software enables the amount of axial chemical inhomogeneity in continuous-cast billets to be explored as a function of the continuous-casting parameters and the physical properties of the steel. Calculations performed for steel with two different initial carbon contents (0.09% and 0.6%) indicated that the proposed method for calculating the effects of soft reduction predicts a substantial (50‐55%) reduction in the axial chemical inhomogeneity of continuous-cast billets.