Surface quality, microstructure and mechanical properties of Cu-Sn alloy plate prepared by two-phase zone continuous casting

Cu-4.7%Sn （mass fraction） alloy plate was prepared by the self-developed two-phase zone continuous casting （TZCC） process. The relationship between process parameters of TZCC and surface quality of the alloy plate was investigated. The microstructure and mechanical properties of the TZCC alloy plate were analyzed. The results show that Cu-4.7%Sn alloy plate with smooth surface can be obtained by means of reasonable matching the entrance temperature of two-phase zone mold and the continuous casting speed. The microstructure of the TZCC alloy is composed of grains-covered grains, small grains with self-closed grain boundaries, columnar grains and equiaxed grains. Compared with cold mold continuous casting Cu-4.7%Sn alloy plate, the room temperature tensile strength and ductility of the TZCC alloy plate are greatly improved.

Relationships between the surface quality of a single crystal copper ingot and the process parameters of a heated mould continuous casting method

The relationships between the surface quality of a single crystal copper ingot and the process parameters of heated mould continuous casting method were studied experimentally using our own design of horizontal heated mould continuous casting apparatus, and the mechanism by which process parameters affect the surface quality of a single crystal copper ingot is analyzed in the present paper. The results show that the process parameters affect the surface quality of a pure copper ingot by affecting the position of the liquid-solid interface in the mould. The position of the liquid-solid interface in the mould must be controlled carefully within an appropriate range, which is determined through a series of experiments, in order to gain a single crystal copper ingot with good surface quality.

Macrosegregation Quality Criteria and Mechanical Soft Reduction for Central Quality Problems in Continuous Casting of Steel

In order to study the central quality of continuously cast tool steel slabs, the simple model has been developed to simulate the macrosegregation quality criteria. The model calculates different quality criteria such as average macro-segregation level criterion “ASL”, its fluctuation level “FSL” and its segregation quality number “SQN”. These criteria are calculated based on the previous measurements of carbon and sulfur concentrations distributions in final region of spray zones and centerline area of lower and upper slab sides. The effect of mechanical soft reduction Technique “MSR” on the slab centerline quality is examined and analyzed. The model results show that MSR affects the quality of centerline areas significantly by different ways based on the casting speed. The experimental and theoretical results clarify that the qualities of different slab sides are different for all collected samples. The model results show also that the accuracy of the macro-segregation quality criteria increases quantitatively with increasing the number of analyzed segregated elements. Therefore, the macrosegregation quality criteria and their distributions can be considered as the most simple and vital tool to evaluate the various slab qualities. Finally, the mechanism of centerline segregation formation with mechanical soft reduction is discussed in this study.

Mold Thermo-Mechanical Rigidity Criterion for Surface Quality of Continuous Casting of Steel

A theoretical investigation of heat flow, solidification and solid shell resistance “Ic” has been undertaken by using a mathematical model and previous plant trials. The ultimate purpose is to develop operating conditions and therefore to improve the surface quality for continuously cast steel slabs. A new simple criterion called mold thermomechanical rigidity “MTMR” has been proposed to evaluate and to improve these purposes. The parameters of MTMR and its non-dimensional number which use to control the surface defects are present in this investigation. Previous plant trails of slab surface defects formation have been investigated thermo-mechanically with this criterion. The predications show that this criterion is very sensitive of operating parameters and is a significant qualitative tool to evaluate the surface quality. From examination of the behavior of MTMR, the susceptibility and mechanism of surface defects formations with MTMR have been primarily discussed.

Propagation form of internal cracks induced by continuous casting soft reduction and control strategy for internal quality

The propagation form of internal cracks induced by continuous casting soft reduction and the control strategy for enhancing the internal quality of 45 steel through industrial trials and a three-dimensional flow-heat transfer-solidification coupling model were investigated.The results showed that the internal cracks induced by soft reduction exhibited a characteristic of being"coarse in the middle and fine at both ends",and displayed an elliptical arc distribution on the loose side of the strand cross section.The cracks originated within the brittle temperature range and propagated inward to the liquid impenetrable temperature and outward to the zero ductility temperature or below.The control strategy for enhancing the internal quality of the 45 steel strand through soft reduction is to adjust the casting speed or the reduction zone appropriately,ensuring that the central solid fraction of the reduction zone falls within the range of 0.33-0.99.At this point,a reasonable reduction amount is allocated to eliminate the center shrinkage cavities and center segregation,even if it results in minor reduction-induced cracks.

Irregular initial solidification by mold thermal monitoring in the continuous casting of steels:A review

Occasional irregular initial solidification phenomena,including stickers,deep oscillation marks,depressions,and surface cracks of strand shells in continuous casting molds,are important limitations for developing the high-efficiency continuous casting of steels.The application of mold thermal monitoring(MTM) systems,which use thermocouples to detect and respond to temperature variations in molds,has become an effective method to address irregular initial solidification phenomena.Such systems are widely applied in numerous steel companies for sticker breakout prediction.However,monitoring the surface defects of strands remains immature.Hence,indepth research is necessary to utilize the potential advantages and comprehensive monitoring of MTM systems.This paper summarizes what is included in the irregular initial solidification phenomena and systematically reviews the current state of research on these phenomena by the MTM systems.Furthermore,the influences of mold slag behavior on monitoring these phenomena are analyzed.Finally,the remaining problems of the formation mechanisms and investigations of irregular initial solidification phenomena are discussed,and future research directions are proposed.

Personalized and continuous care intervention affects rehabilitation,living quality,and negative emotions of patients with breast cancer

BACKGROUND Breast cancer is among the most common malignancies worldwide.With progress in treatment methods and levels,the overall survival period has been prolonged,and the demand for quality care has increased.AIM To investigate the effect of individualized and continuous care intervention in patients with breast cancer.METHODS Two hundred patients with breast cancer who received systemic therapy at The First Affiliated Hospital of Hebei North University(January 2021 to July 2023)were retrospectively selected as research participants.Among them,134 received routine care intervention(routing group)and 66 received personalized and continuous care(intervention group).Self-rating anxiety scale(SAS),self-rating depression scale(SDS),and Functional Assessment of Cancer Therapy-Breast(FACT-B)scores,including limb shoulder joint activity,complication rate,and care satisfaction,were compared between both groups after care.RESULTS SAS and SDS scores were lower in the intervention group than in the routing group at one and three months after care.The total FACT-B scores and five dimensions in the intervention group were higher than those in the routing group at three months of care.The range of motion of shoulder anteflexion,posterior extension,abduction,internal rotation,and external rotation in the intervention group was higher than that in the routing group one month after care.The incidence of postoperative complications was 18.18%lower in the intervention group than in the routing group(34.33%;P<0.05).Satisfaction with care was 90.91% higher in the intervention group than in the routing group(78.36%;P<0.05).CONCLUSION Personalized and continuous care can alleviate negative emotions in patients with breast cancer,quicken rehabilitation of limb function,decrease the incidence of complications,and improve living quality and care satisfaction.

Solidification of horizontally continuous casting of super-thin slab in stable magnetic field and alternating current

The solidified structures of horizontally continuous casting（HCC） of super-thin slab and its relations with the current were studied under the electromagnetic vibration（EMV）.The results show that,under the action of the periodical forces from EMV,the solidified structures of the super-thin slab of pure tin is greatly refined,and the extent of grain refinement is increased with the magnitude of alternating current.For the Sn-10%Pb alloy,it is shown that the EMV promotes the growth of equiaxed grains in the center of super-thin slab,and the grains are refined with the alternating current increasing.This is useful to prevent some solidification defects in the horizontally continuous casting of super-thin slab,such as columnar grains butting,porosity,inclusions and gases gathering,and composition segregation in the centre of slab.

THE COMPUTATION AND EXPERIMENT ANALYSIS OF ELECTROMAGNETIC CONTINUOUS CASTING WITH SOFT-CONTACTED MOULD

In this paper, coupling the quasi-3D numerical simulation of electromagnetic field and the experiments of continuous casting with soft-contacted mould with some metals such as tin, aluminum, copper and steel, the electromagnetic characteristics of continuous casting with soft-contacted mould is analyzed. It is shown that the electromagnetic pressure on the surface of billet is increasing with the rising of power frequency as a logarithmically parabolic function, with that of electric conductivity of billet as a power junction, and with that of the current in inductor as a parabolic junction.

EFFECT OF INTERMITTENT HIGH FREQUENCY MAGNETIC FIELD ON INITIAL SOLIDIFICATION IN CONTINUOUS CASTING

Contacting state between molten metal and a mold and initial solidification process of continuously cast metals can be controlled by imposing an intermittent magnetic field.In this study, effect of the intermittent magnetic field on the initial solidification ofcontinuoasly cast metals was investigated by measuring the temperature distribution in the melt pool and the initial solidification starting position of shells. It was found that under the condition with intermittent magnetic field, the melt near meniscns is in slow cooling state, the initial solidification starting position descends, initial solidification shell thickens and the liquid-solid interface becomes smooth.

Process Parameters of Manufacturing Single Crystal Copper by Heated Mold Continuous Casting

The effect of process parameters on the surface quality of single crystal copper ingot was studied through experiment with a self-designed horizontal heated mould continuous casting apparatus,and the mechanism was analyzed.The results show that the process parameters affect the surface quality of pure copper ingot by affecting the position of the liquid-solid interface in the mould.The position of the liquid-solid interface in the mould must be controlled carefully in an appropriate range determined through experiments in order to gain a single crystal copper ingot with a high surface quality.

Numerical simulation of fluid flows in a slab continuous casting mold under electromagnetic stirring

This study established a three-dimensional mathematical model to determine the fluid flow in a slab continuous casting mold under an electromagnetic stirring force. The flow structure and distribution were studied with respect to different continuous casting parameters and stirring current. Based on the calculation results, the mold flux entrapment index in free surface and velocity uniformity index were used to evaluate the flow field in the mold. The theoretical basis for the optimization of the flow field structure was provided. The study also suggested an optimization method for electromagnetic stirring parameters.

Horizontal continuous casting process under electromagnetic field for preparing AA3003/AA4045 clad composite hollow billets

A modified horizontal continuous casting process under the electromagnetic field was proposed for preparing AA3003/ AA4045 clad composite hollow billets. To investigate the effect of electromagnetic field on this process, a comprehensive three-dimensional model was developed. Two cases with and without electromagnetic field were compared using the simulations. When rotating electromagnetic stirring is applied, the flow pattern of fluid melt is greatly modified; the mushy zone becomes much wider, the temperature profile becomes more uniform, and the solid fraction decreases for both the external and internal alloy melt layers. These modifications are beneficial for the formation of a bimetal interface and fine and uniform grain structure of the clad composite hollow billet. Experiments conducted using the same electrical and casting parameters as the simulations verify that under the electromagnetic field the microstructure of the clad composite hollow billet becomes fine and the diffusion of the elements at the interface is promoted.

Microstructure and properties of Al-0.70Fe-0.24Cu alloy conductor prepared by horizontal continuous casting and subsequent continuous extrusion forming

A novel process for manufacturing A1-0.70Fe-0.24Cu alloy conductor was proposed, which includes horizontal continuous casting and subsequent continuous extrusion forming （Conform）. The mechanical properties, electrical conductivity and the compressed creep behaviour of the alloy were studied. The results indicate that the Conform process induces obvious grain refinement, strain-induced precipitation of AI7CuzFe phase and the transformation of crystal orientation distribution. The processed alloy has good comprehensive mechanical properties and electrical conductivity. Moreover, a better creep resistance under the conditions of 90 ~C and 76 MPa is shown compared with pure A1 and annealed copper, and the relationship between primary creep strain and time may comply with the logarithmic law. The enhanced properties are attributed to the grain refinement as well as the fine and homogeneously distributed thermally stable A1Fe and A17Cu2Fe precipitation phases.

Effect of Electromagnetic Frequency on Microstructures of Continuous Casting Aluminum Alloys

The relationship between electromagnetic frequency and microstructures of continuous casting aluminum alloys was studied. 7075 aluminum alloy ingot of 100 mm in diameter was produced by electromagnetic continuous casting process, the microstructures of as-cast ingot was examined by scanning electron microscopy (SEM) equipped with energy dispersive spectrometer (EDS). The results showed that electromagnetic frequency greatly influenced segregation and microstructures of as-cast ingot, and product quality can be guaranteed by the application of a proper frequency. Electromagnetic frequency plays a significant role in solute redistribution; low frequency is more efficient for promoting solution of alloying elements.

Study on Multiple Electromagnetic Continuous Casting of Aluminum Alloy

To obtain semi-solid Al alloy billet with high quality, an investigation was carried out by imposing a multiple magnetic field from the outside of a copper mold in the continuous casting. AISi6Mg2 alloy designed for semi-solid metal （SSM） processing was continuously cast through a submerged entry nozzle under various conditions. Effects of multiple magnetic field on meniscus motion, temperature distribution and billet quality were examined. The experimental results showed that meniscus disturbance caused by electromagnetic stirring could be controlled effectively and the surface quality of semi-solid AI alloy billet was improved greatly, and an uniformly fine, globular microstructure across the transverse section of the billet was achieved by optimizing the distribution of multiple magnetic field.

Meniscus Behavior in Electromagnetic Soft-Contact Continuous Casting Round Billet Mold

Using molten Pb-Sn-Bi alloy, the meniscus shape under high frequency magnetic field of φ100 mm round billet caster was investigated. The effect of some parameters on meniscus shape was studied. The results show that for a mold with 12 segments, the meniscus shape is relatively stable. With increasing power input, the menis- cus height increases with intensification of fluctuation. For the given caster, the reasonable power input is about 70 kW. The coil should be near to the top of mold and/or the initial meniscus should be near to the center of the coil. The lower the frequency, the higher is the meniscus height. With increasing frequency, the free surface is more flattened and meniscus becomes more stable. In practice, the power input should be increased simultaneously with frequency. The optimal frequency is about 20 kHz.

Microstructure and mechanical properties of BFe10 cupronickel alloy tubes fabricated by a horizontal continuous casting with heating-cooling combined mold technology

A new horizontal continuous casting method with heating-cooling combined mold （HCCM） technology was explored for fabri- cating high-quality thin-wall cupronickel alloy tubes used for heat exchange pipes. The microstructure and mechanical properties of BFe 10 cupronickel alloy tubes fabricated by HCCM and traditional continuous casting （cooling mold casting） were comparatively investigated. The results show that the tube fabricated by HCCM has smooth internal and external surfaces without any defects, and its internal and external surface roughnesses are 0.64 μm and 0.85 μm, respectively. The tube could be used for subsequent cold processing without other treatments such as surface planning, milling and acid-washing. This indicates that HCCM can effectively reduce the process flow and improve the pro- duction efficiency of a BFel0 cupronickel alloy tube. The tube has columnar grains along its axial direction with a major casting texture of {012}〈 621 〉. Compared with cooling mold casting （6 = 36.5%）, HCCM can improve elongation （3 = 46.3%） by 10% with a slight loss of strength, which indicates that HCCM remarkably improves the cold extension performance of a BFe 10 cupronickel alloy tube.

Fluid Flow and Solidification Simulation in Beam Blank Continuous Casting Process With 3D Coupled Model

Based on turbulent theory, a 3D coupled model of fluid flow and solidification was built using finite difference method and used to study the influence of superheating degree and casting speed on fluid flow and solidification, analyze the interaction between shell and molten steel, and compare the temperature distribution under different technological conditions. The results indicate that high superheating degree can lengthen the liquid-core depth and make the crack and breakout possible, so suitable superheating should be controlled within 35℃ according to the simulation results. Casting speed which is one of the most important technological parameters of improving production rate, should be controlled between 0. 85 m/min and 1.05 m/min and the caster has great potential in the improvement of blank quality.

Liquid-solid interface control of BFe10-1-1 cupronickel alloy tubes during HCCM horizontal continuous casting and its effect on the microstructure and properties

Based on horizontal continuous casting with a heating-cooling combined mold （HCCM） technology, this article investigated the effects of processing parameters on the liquid-solid interface （LSI） position and the influence of LSI position on the surface quality, microstructure, texture, and mechanical properties of a BFe10-1-1 tube （φ50 mm × 5 mm）. HCCM efficiently improves the temperature gradient in front of the LSI. Through controlling the LSI position, the radial columnar-grained microstructure that is commonly generated by cooling mold casting can be eliminated, and the axial columnar-grained microstructure can be obtained. Under the condition of 1250℃ melting and holding temperature, 1200-1250℃ mold heating temperature, 50-80 mm/min mean drawing speed, and 500-700 L/h cooling water flow rate, the LSI position is located at the middle of the transition zone or near the entrance of the cooling section, and the as-cast tube not only has a strong axial columnar-grained microstructure （{hkl}〈621〉, {hkl}〈221〉） due to strong axial heating conduction during solidification but also has smooth internal and external surfaces without cracks, scratches, and other macroscopic defects due to short solidified shell length and short contact length between the tube and the mold at high temperature. The elongation and tensile strength of the tube are 46.0%-47.2% and 210-221 MPa, respectively, which can be directly used for the subsequent cold-large-strain processing.