This article discusses issues related to continuous casting of brass. The tested material was CuZn39Pb2 brass with the use of continuous casting and different parameters of the process. The position consists of a melting furnace with a graphite refining pot of about 4000 cm3 chuting capacity, a graphite crystallizer of 9,5 mm nominal diameter, a primary and secondary cooling system and an extracting system as well. The analysis was carried out in terms of technological parameters of the process and type of charge. Highlighted: feedrate ingot, number of stops, and technological temperatures. The surface quality of the obtained ingots and the structure were analyzed. The most favorable conditions were indicated and technological recommendations indicated. They have been distinguished for ingots for plasticity and other technologies. Favorable casting conditions are low feed and low temperature. Due to the presence of impurities coming from the charge it is disadvantageous to have Ni greater than 0.053% by mass, and Fe more than 0.075% by mass. It is recommended to maintain a high zinc content in the melt which is associated with non-overheating of the metal during casting and earlier melting.
In this paper results of microstructural observations for series of CuZn39Pb2 alloys produced from qualified scraps are presented. The individual alloy melts were differentiated in terms of thermal parameters of continuous casting as well as refining methods and modifications. Structural observations performed by SEM and TEM revealed formation of different types of intermetallic phases including “hard particles”. EDS results show that “hard particles” are enrich in silicon, phosphorus, iron, chromium and nickel elements. Additionally, formation of Al-Fe-Si and Al-Cr in alloy melts was observed as well. It was found that quantity and morphology of intermetallic phases strongly depends upon the chemical composition of raw materials, process parameters, modifiers and refining procedure applied during casting. It was observed that refining process results in very effective refinement of intermetallic phases, whereas modifiers, particularly carbon-based, results in formation of large particles in the microstructure.
The temperature of liquid steel for continuous casting determines the casting speed and cooling conditions. The failure to meet the required casting process parameters may result in obtaining slabs of inconsistent quality. Numerical methods allow for real processes to be modelled. There are professional computer programs on the market, so the results of the simulations allow us to understand the processes that occur during casting and solidification of a slab. The study attempts to evaluate the impact of the superheat temperature on the slab structure based on the industrial operating parameters of the continuous casting machine.
The presented results of investigations are part of a larger study focused on the optimization of the flow and mixing of liquid steel in the industrial tundish of continuous casting machine. The numerical simulations were carried out concern the analysis of hydrodynamic conditions of liquid steel flow in a tundish operating in one of the national steelworks. Numerical simulations were performed using the commercial code ANSYS Fluent. The research concerns two different speeds of steel casting. In real conditions, these speeds are the most commonly used in the technological process when casting two different groups of steel. As a result of computational fluid dynamics (CFD) calculations, predicted spatial distributions of velocity and liquid steel turbulence fields and residence time distribution (RTD) curves were obtained. The volume fractions of different flows occurring in the tundish were also calculated. The results of the research allowed a detailed analysis of the influence of casting speed on the formation of hydrodynamic conditions prevailing in the reactor.
The paper presents the research results of horizontal continuous casting of ingots of aluminium alloy containing 2% wt. silicon (AlSi2).
Together with the casting velocity (velocity of ingot movement) we considered the influence of electromagnetic stirring in the area of the
continuous casting mould on refinement of the ingot’s primary structure and their selected mechanical properties, i.e. tensile strength, yield
strength, hardness and elongation. The effect of primary structure refinement and mechanical properties obtained by electromagnetic
stirring was compared with refinement obtained by using traditional inoculation, which consists in introducing additives, i.e. Ti, B and Sr,
to the metal bath. On the basis of the obtained results we confirmed that inoculation done by electromagnetic stirring in the range of the
continuous casting mould guarantees improved mechanical properties and also decreases the negative influence of casting velocity, thus
increasing the structure of AlSi2 continuous ingots.
In paper is presented results of studies concerning ingot of Al with a purity of 99.5% cast with use of stand of horizontal continuous
casting. Mainly together with casting velocity was considered influence of electromagnetic stirrer, which was placed in continuous casting
mould on refinement of ingots structure and theirs usability to plastic deformation. Effect of structure refinement and usability to plastic
deformation obtained by influence of electromagnetic stirring was compared with refinement obtained by use of traditional inoculation,
which consists in introducing of additives i.e. Ti and B to metal bath. On the basis of obtained results was affirmed that inoculation
realized by electromagnetic stirring in range of continuous casting mould guarantees improvement in structure refinement and usability to
rolling of pure Al continuous ingots.
There has been a growing interest in the peritectic due to increasing productivity, quality, and alloy development. Differential scanning calorimetry (DSC) has traditionally been used to study steel solidification but suffers significant limitations when measuring the solidus and peritectic. This work covers a new thermal analysis system that can characterize the peritectic reaction. Heats of AISI/SAE 1030 and 4130 steel were poured to provide some benchmarking of this new technique. The peritectic was detected and the reaction temperature measured. Measurements agree reasonably well with reference information. A review of the literature and thermodynamic calculations did find some disagreement on the exact temperatures for the peritectic and solidus. Some of this difference appears to be related to the experimental techniques employed. It was determined that the system developed accurately indicates these reaction temperatures. The system provides a unique method for examining steel solidification that can be employed on the melt deck.
In paper is presented idea of construction and influence of selected parts of stand of horizontal continuous casting on quality of pure Al and AlSi2
alloy ingots. The main parts of the made stand belong to induction furnace, which is also tundish, water cooled continuous casting mould, system
of recooling, system of continuous ingot drawing and cutting. Mainly was considered influence of electromagnetic stirrer, which was placed
in continuous casting mould on refinement of ingots structure. Effect of structure refinement obtained by influence of electromagnetic stirring was
compared with refinement obtained by use of traditional inoculation, which consists in introducing of additives i.e. Ti and B to metal bath. The
results of studies show possibility of effective refinement of Al and AlSi2 alloy primary structure, only with use of horizontal electromagnetic field
and without necessity of application of inoculants. This method of inoculation is important, because inoculants decrease the degree of purity
and electrical conductivity of pure aluminum and moreover are reason of point cracks formation during rolling of ingots.
As in many thermal processing technologies, there is a delicate balance between productivity and quality during ingot cooling process. Higher cooling velocities increase productivity but also create higher temperature gradients inside the ingot. Such a fast cooling does not leave sufficient time to establish the equilibrium within the solid, thus the final metal structure is strongly affected by the set up cooling mode throughout the liquid metal solidification. The first intention in this paper is to compare between three cooling modes in order to identify the required mode for a continuous casting process. Then, we study the influence of heat transfer coefficient on metal liquid-to-solid transition through the spray-cooled zone temperature and the metal latent heat of solidification. A gray iron continuous casting process subjected to water-sprays cooling was simulated using the commercial software for modeling and simulating multiphysics and engineering problems. The primary conclusions, from the obtained results, show the forcefulness of water spray cooling regarding standard cooling. Afterward, we highlight the great influence of heat transfer coefficient on the location of transition region as well as the relationship between heat transfer coefficient, wall outer temperature, latent heat dissipation, and the solidification time.
The mold temperature of the downward continuous unidirectional solidification (CUS) cannot be controlled higher than the liquidus of alloys to be cast. Therefore, the continuous casting speed becomes the main parameter for controlling the growth of columnar crystal structure of the alloy. In this paper, the tin bronze alloy was prepared by the downward CUS process. The microstructure evolution of the CUS tin bronze alloy at different continuous casting speeds was analysed. In order to further explain the columnar crystal evolution, a relation between the growth rate of columnar crystal and the continuous casting speed during the CUS process was built. The results show that the CUS tin bronze alloy mainly consists of columnar crystals and equiaxed crystals when the casting speed is low. As the continuous casting speed increases, the equiaxed crystals begin to disappear. The diameter of the columnar crystal increases with the continuous casting speed increasing and the number of columnar crystal decreases. The growth rate of columnar crystal increases with increasing of the continuous casting speed during CUS tin bronze alloy process.
Determining the boundary conditions of heat transfer in steel manufacturing is a very important issue. The heat transfer effect during contact of two solid bodies occurs in the continuous casting steel process. The temperature fields of solids taking part in heat transfer are described by the Fourier equation. The boundary conditions of heat transfer must be determined to get an accurate solution to the heat conduction equation. The heat flux between the tool and the object processed depends mainly on temperature, pressure and time. It is very difficult and complicated to accomplish direct identification and determination of the boundary conditions in this process. The solution to this problem may be the construction of a process model, performing measurements at a test stand, and using numerical methods. The proposed model must be verified on the basis of parameters which can easily be measured in industrial processes. One of them is temperature, which may be used in inverse methods to determine the heat transfer coefficient. This work presents the methodology for determining the heat flux between two solid bodies staying in contact. It consists of two stages – the experiment and the numerical computation. The problem was solved by using the finite element method (FEM) and a numerical program developed at AGH University of Science and Technology in Krakow. The findings of the conducted research are relationships describing the value of the heat flux versus the contact time and surface temperature.
In this paper, the mathematical model and numerical simulations of the molten steel flow by the submerged entry nozzle and the filling process of the continuous casting mould cavity are presented. In the mathematical model, the temperature fields were obtained by solving the energy equation, while the velocity fields were calculated by solving the momentum equations and the continuity equation. These equations contain the turbulent viscosity which is found by solving two additional transport equations for the turbulent kinetic energy and its rate of dissipation. In the numerical simulations, coupling of the thermal and fluid flow phenomena by changes in the thermophysical parameters of alloy depending on the temperature has been taken into consideration. This problem (2D) was solved by using the finite element method. Numerical simulations of filling the continuous casting mould cavity were performed for two variants of liquid metal pouring. The effect of the cases of pouring the continuous casting mould on the velocity fields and the solid phase growth kinetics in the process of filling the continuous casting mould was evaluated as these magnitudes have an influence on the high quality of the continuous cast steel slab.
Investigation of the tensile and fatigue properties of cast magnesium alloys, created by the heated mold continuous casting process (HMC),
was conducted. The mechanical properties of the Mg-HMC alloys were overall higher than those for the Mg alloys, made by the
conventional gravity casting process (GC), and especially excellent mechanical properties were obtained for the Mg97Y2Zn1
-HMC alloy.
This was because of the fine-grained structure composed of the -Mg phases with the interdendritic LPSO phase. Such mechanical
properties were similar levels to those for conventional cast aluminum alloy (Al84.7Si10.5Cu2.5Fe1.3Zn1 alloys: ADC12), made by the GC
process. Moreover, the tensile properties (UTS and f
) and fatigue properties of the Mg97Y2Zn1
-HMC alloy were about 1.5 times higher
than that for the commercial Mg90Al9Zn1
-GC alloy (AZ91). The high correlation rate between tensile properties and fatigue strength
(endurance limit: l
) was obtained. With newly proposed etching technique, the residual stress in the Mg97Y2Zn1 alloy could be revealed,
and it appeared that the high internal stress was severely accumulated in and around the long-period stacking-order phases (LPSO). This
was made during the solidification process due to the different shrinkage rate between α-Mg and LPSO. In this etching technique, microcracks
were observed on the sample surface, and amount of micro-cracks (density) could be a parameter to determine the severity of the
internal stress, i.e., a large amount to micro-cracks is caused by the high internal stress.
Detailed studies of the movement of liquid steel (hydrodynamics) on a real object are practically impossible. The solution to this problem are physical modelling carried out on water models and numerical modelling using appropriate programs. The method of numerical modelling thanks to the considerable computing power of modern computers gives the possibility of solving very complex problems.
The paper presents the results of model tests of liquid flow through tundish. The examined object was model of the twonozzle tundish model. The ANSYS Fluent program was used to describe the behavior of liquid in the working area of the tundish model. Numerical simulations were carried out using two numerical methods of turbulence description: RANS (Reynolds-Averaged Navier-Stokes) – model k-ε and LES (Large Eddy Simulation). The results obtained from CFD calculations were compared with the results obtained using the water model.
The article presents the results of investigations performed on segregation of elements in the billets. The research were performed under standard industrial conditions, during high carbon steel production cycle. Probes (templates with the thickness of 20 mm) were taken from billets with square cross-section of 160 mm. Segregation of elements was determined based on the quantitative analysis of results performed by using spark spectrometry pursuant to PN-H-04045. Changes in concentrations of elements were analysed along two cross-sections. Element contents were performed at points distanced from each other by approx. 10 mm. The segregation of carbon, sulphur and phosphorus was determined for different billets.