Ingot Molds Research Articles

The Influence of Insertion Depth of Inorganic Materials on Solidification Microstructure and Segregation of 2.5-ton 42CrMo Ingot

In this work, a novel internal heat absorption technology using inorganic material rods is employed during the solidification process of steel ingots, aiming to control their solidification and improve the quality of the final product. The study investigates the effect of the insertion depth of inorganic materials on the solidification microstructure and macrosegregation of 2.5-ton 42CrMo ingots. The mechanical properties of samples from the product are also tested. A numerical simulation model for casting 2.5-ton ingots is established and implemented in Ansys Fluent fluid simulation software, with inorganic material rods set at different preset depths. The simulation explores the physical processes of the melting and floating of inorganic materials in molten steel, as well as their effects on the temperature and flow fields of the material. The results show that deeper insertion of inorganic materials (200 mm from the hot top) reduces the tendency for macrosegregation compared to that at the insertion depth of 100 mm. Specifically, the positive segregation area decreases by 10.35%, while the negative segregation area decreases by 15.32%. Moreover, deeper insertion results in a significant refinement of the solidification microstructure, ultimately enhancing the mechanical properties of the products machined from the ingots (i.e., the yield strength increased by 4.7%). The numerical simulation results indicate that as the placement depth of inorganic materials in the ingot mold increases, the cooling effect becomes more significant, the flow area of molten steel initiated by the inorganic materials expands, and the linear velocity of the double-circle flow increases. This further explains why the solidification quality of the ingots improves with the increasing placement depth of inorganic materials.

Evaluation of the Possibilities for Improving Durability of Large Ingot Molds Made of Pig Iron Using Vibration Treatment of the Melt

Evaluation of the Possibilities for Improving Durability of Large Ingot Molds Made of Pig Iron Using Vibration Treatment of the Melt

ЕКСПЕРИМЕНТАЛЬНЕ ДОСЛІДЖЕННЯ ТОЧНОСТІ ПРОКАТКИ НА СТАНІ 800

The purpose of the work is an experimental study of the process of square sections rolling on the rolling mill 800 to determine the influence of rolling parameters on the dimensions and length of the roll. During the study, variations in ingot mass, rolling dimensions, and rolling length were determined, regression equations and correlation coefficients were obtained for the dependence of rolling dimensions and length on the ingot mass, changes in interroll gap and time delay before the finishing stand. It was established that the ingot mass variates within significant limits - 638 kg, which is caused by the melt mass variations. Variations in the mass of the ingot within one ingot mold stool are caused by the dimensions of the ingot molds and are within 154 kg. Variations in the dimensions of the roll are carried out within the following limits: thickness - 1.0 mm, width - 0.5 mm, length - 5.3 m. The change of the interroll gap can be used to correct the length of the finished roll in a small range of lengths, if the mass variations occur within accuracy of ingot casting on one ingot mold stool. It is necessary to take additional measures to stabilize the weight of the ingot. The influence of delays in the rolling train, which occur during rolling and lead to instability of the rolling temperature regime, for this type of profiles does not significantly affect the dimensions of the cross section and the length of the roll.

Comparison and Parametric Analysis of Thermoelectric Generator System for Industrial Waste Heat Recovery with Three Types of Heat Sinks: Numerical Study

In this study, a fluid–thermal–electrical multiphysics numerical model was developed for the thermal and electrical analyses of a heat sink-based thermoelectric generator (TEG) in a waste heat recovery system used for casting a bronze ingot mold. Moreover, the model was validated based on experimental data. Heat sinks were installed on the hot side of the TEG module to recover the waste heat from the flue gas generated in the casting process. The numerical results of the thermal and electrical characteristics of a plate fin (PF)-based TEG showed good agreement with the experimental findings. Numerical simulations of heat sinks with three different fin structures—PF, cylinder pin fin (CPF), and rectangular pin fin (RPF)—were conducted. The simulated system pressure drop, hot- and cold-side temperature difference in the TEG module, TEG power output, and TEG efficiency were compared for the differently designed fin structures. The results showed that for the same fin area, the CPF heat sink-based TEG system achieved a lower pressure drop, higher power output, and higher efficiency than the other two designs. This was particularly true when the velocity of the flue gas and the fin height exceed 5 m/s and 28.6 mm, respectively. Therefore, for low and high flue gas velocities, PF and CPF heat sinks are recommended as the best choices, respectively.

Prediction model of interfacial heat transfer coefficient changing with time and ingot diameter

Abstract We established and simulated finite element solidification models of ingots with 180, 380, 800, 1,300, and 1,880 mm diameters, and the solidification process temperature distributions for the five ingot sizes were assessed by Fluent. On this basis, we established a mathematical model for the interfacial heat transfer coefficient between the ingot and the ingot mold, as well as the ingot diameter and solidification time, using the regression analysis method. The results showed that the change law for the interfacial heat transfer coefficients of the ingots with different sizes and times conformed to the change law of the exponential function, and the interfacial heat transfer coefficient and the ingot diameter had a linear relationship. The interfacial heat transfer coefficient, based on a measured temperature of about 36 tons of ingot with an average diameter of 1,500 mm and about 8.5 tons of ingot with an average diameter of 820 mm, was compared to the interfacial heat transfer coefficient calculated by the model. We found that the variation law of the two was essentially the same, indicating that this model could correctly reflect the interfacial heat transfer coefficient between the ingot and the ingot mold in the literature.

Optimization Steel ingot Mould’ Riser Height Based on Solidification Simulation

Solidification process of 13.5t P91 steel ingot with different riser heights were simulated by software and predicted the distribution of shrinkage cavity. The simulation results showed the shrinkage cavity in the precedent ingots is much deeper. The simulation results is agreement well with experiment results. Therefore, the riser height was designed by solidifation simulation and verified by experiments and the results showed that optimized riser height can eliminate shrikage cavity and improve the quality of steel ingot.

Improved Molten Metal Sampling Method for Hydrogen Content Analysis

The main disadvantage of the existing sampling method of metal for hydrogen content analysis is the contact of metal with air moisture during an open overpour from a metal scoop to the ingot mold. In response, a novel method is proposed for sampling molten aluminum and its alloys for hydrogen content analysis by dipping a conical ingot mold sampler into the melt. The work was performed at the Sayanogorsk aluminum plant UC RUSAL in the technological workflow from a transport ladle to the casting machine. Hydrogen analysis results using the proposed method are compared to those of the sampling method using the Rensley chill mold. The error in the hydrogen content measurement of the sample under the existing sampling scheme with overpour of metal from a metal scoop into the ingot mold was confirmed. The hydrogen concentration in the samples taken in the Rensley chill mold is less, on average, by 0.019 cm3/100 g Al, than in the samples obtained using the newly developed ingot mold sampler. Results of the study reveal that the proposed sampling method provides an additional advantage when sampling molten metal.

Effects of Weight‐Compatible Design on Ingot Solidification

The problem of complex and various ingot moulds has bothered special steel enterprises. Herein, three ingot‐weight‐compatible (IWC) designs are described. The 39 tons mould is adapted to cast at most 45 tons of molten steel. The effect of three IWC designs on shrinkage cavity, porosity and macrosegregation is studied. The simulation is based on a polyphase coupled model for momentum, energy, and mass conservation equations. On the basis of the experimental results and previous literature, the interfacial heat transfer coefficient is established. Through finite difference method (FDM) simulation, the effect of the three IWC designs on the solidification is studied. The predictions of shrinkage porosity and macrosegregation are obtained. With the increase of ingot weight, the shrinkage cavity from the hot top is deeper in the three IWC designs. The Niyama criterion is found to be the condition under G/L0.5 < constant (G and L are the temperature gradient and cooling rate, respectively). With this criterion, the extent of centerline shrinkage porosity is predicted. Subsequently, utilizing the three compatible designs, the simulated results uncover that the centerline shrinkage porosity is serious. In addition, it is significant to note that the macrosegregation shows different characteristics.

Influence of Mould Slenderness Ratio on the Solidification of Heavy Ingots by Numerical Simulation

The quality of heavy ingot normally depends on the processing factor and ingot mould type. Based on the ingot mould type only, the quality and solidification process of a 96-ton ingot moulds with different slenderness-ratios have been studied numerically using the software package ProCAST. The results show that the position of shrinkage porosity moves up and the macroporosity in the ingot center increases prominently as slenderness-ratio increasing, meanwhile, the inclusion-floating time through the middle and bottom part of ingot decreases, and A-segregation alleviates as well. The correlation between the quality and slenderness-ratio of the ingot is not a liner relationship, when the slenderness ratio is 1.4, the ingot has better quality.

Comparison of work environment air quality and application of geostatistic technique in the spatial distribution of PM2.5 and PM10 in a number of industrial workshops

Introduction: Air quality in industrial workshops is affected by various harmful chemical agents. Purpose of this study was to compare work environment air quality in a number of industrial workshops based on the mass concentration and number of suspended particles in air and application of Kriging geostatistical method in industries. Materials and Methods: This observational study was carried out in four workshops including cuprous waste separation works, rolling and cutting, casting and copper smelting, manufacturing aluminum products and double-glazed glass production. Using particle mass counter sampler of Tes 5200 model, mass concentration and number concentration of suspended particles in row of different diameters were measured. The spatial distribution map of PM2.5 and PM10 in each of workshops was prepared using Kriging geostatistic method in GIS environment Version 10.5. Results: The highest mass concentration (8.42 mg/m3) and number concentration (445058 Particle/lit in differential mode and 885446 Particle/lit in cumulative mode) were measured in the manufacturing aluminum products workshop. The highest mass concentration and number concentration of suspended particles were obtained for row diameters of 10 µm and 0.5 µm, respectively. Interpretation of Kriging maps showed that various areas of the industries such as radiation furnace, scrap press, aluminum smelter, sieve, diamond machine, glass furnace and ingot molds had the highest frequency of PM2.5 and PM10. Conclusion: Engineering control actions such as installation of ventilation systems in halls and design and installation of a local hood in the entrance sections of the aluminum smelting furnace and sieve in manufacture of aluminum products workshop and copper ingot molds in casting and smelting workshop is essential for improved air quality.

INDUSTRIAL TECHNOLOGY OF MANUFACTURING ULTRA-STRENGTH NANOBAINITIC STEEL PLATES

Nanobainitic steel grades are a new construction material with a strength in the range of 1.9–2.2 GPa, at the same time characterised by good plasticity. Currently, the works on the development of nanobainitic steels at Łukasiewicz – IMŻ have entered the commercialisation phase. One of the main applications of ultra-strength nanobainitic steel plates is armour systems. In order to optimise the parameters of the production process of nanobainitic steel plates, microstructure examination and measurement of mechanical properties were carried out at intermediate stages of production and after final heat treatment. The results of industrial steel and plate production operations were assessed, including smelting and casting into ingot moulds, preparation of the rolling mill charge, hot rolling, plate production as well as intermediate and final heat treatment. Critical technological operations that may adversely affect the quality and performance of plates were identified. The directions for technology modification that reduce or eliminate threats of plate deterioration were formulated.

Forecasting Increase of Quality of Large-Sized Forgings Used for Stamping, Piercing, and Rolling of High-Duty Products

When utilizing current combined systems of manufacturing large-sized shaft forgings, there is a tendency towards using an integrated approach, which consists in optimizing the shape of forged ingots and methods of their forging, intensifying shear strains in the axial zone of the ingots during their plastic deformation, and eliminating asymmetry of external forces at various points along the cross section of the ingot being deformed. This paper presents the results of the comparative analysis of quality of shaft forgings when forging ingots with a three-beam symmetric and asymmetric cross-section, as well as with the traditional octahedral cross-section, are used for the manufacture of shaft forgings. It has been shown that the use of forging ingots with a three-beam symmetrical and asymmetrical cross section provided an increase of KCU by an average of 4.3% and 13.1%, and of density by 17.5% and 21.0%, respectively, in the absence and presence of inert gas (argon) blowdown of the melt in the casting ladle before casting it into ingot molds. Their use also contributes to an increase in the number of forgings, suitable for ultrasonic testing, according to the C/c class with a permissible equivalent discontinuity diameter of ≤ 3 mm.

Modeling of the alloy solidification modified by refractory nano-size particles

The authors propose a mathematical model of non-equilibrium crystallization of a binary alloy with modifying refractory nano-sized particles. The model describes heat transfer processes, as well as heterogeneous nucleation and crystallization of two components of the melt. The nucleation of the crystalline phase occurs on the surface of the nanoparticles during the supercooling of the melt. The liquidus temperature in the melt depends on the concentration of the dissolved alloying component, which is determined by the non-equilibrium lever equation. When the metal is cooled down to the eutectic temperature, the solidification of the alloy α-phase takes place, followed by solidification of β-phase if the cooling continues. The growth rate of the crystal phase is proportional to the supercooling value. The volume of the solid phase formed around the nucleus determines the size of the grain structure in the solidified alloy. The article depicts numerical simulation of aluminum melt solidification in cylindrical ingot mold, carried out by the authors. The parameters of heat exchange of the melt-mold system with the environment are available from experiments. The conditions of nucleation, crystallization rate, supercooling and solidification time prove to significantly differ within the cast. The area with the finest structure of the solidified metal is located near the wall of the mold. The calculated size of the grain structure in the casting is consistent with the experimental results. Comparing the results of numerical calculation with the data of a physical experiment on measuring the temperature during solidification of the melt and studying the properties of the cast confirm reliability of the proposed model.

Study of corrosion mechanism of cast iron in molten aluminum

The corrosion mechanism of three aluminum ingot mold materials used by Chinese aluminum electrolytic enterprises in molten aluminum was studied: The three materials are pearlite cast iron(PCI) contains vermicular graphite, lamellar graphite, and spherical graphite respectively. After 800 °C molten aluminum corrosion for 4 h, the intermetallic compound (IMC) layers of Fe2Al5 and FeAl3 is formed at the interface. It was found that the volume of spherical graphite in IMC was reduced to 20%, and lamellar graphite aggregated in the IMC layer. The average thickness of the Fe2Al5 layer in PCI1, PCI2 and PCI3 is about 180 μm, 100 μm and 101 μm, respectively. The weight loss rate of PCI1 is 2.57 (mg cm−2)min−1, PCI2 is 2.20 (mg cm−2)min−1, and PCI3 is 2.24(mg cm−2)min−1. There are dispersed Cr and Mo carbides in the IMC layer. Si-rich ribbon-shaped region was found at the interface between cast iron and IMC. The needle-like precipitates (Al4C3) were observed only at the only at the boundary between cast iron and IMC in PCI1.

Effect of mould design on the Niyama criteria during solidification of CH3C 80t ingot

ABSTRACT Eighty tons of CH3C steel ingots used as backup rollers which should have high wear resistance and fatigue strength. Centreline Shrinkage porosity of 80 tons steel ingot reduces resistance to fatigue. The shapes of the mould and the feeding design have the greatest impact on the formation of shrinkage porosity around the central axis. Therefore, parameters such as the ratio of height to average ingot diameter, the polygon number of ingot and concave radius of the ingot were studied on the formation of shrinkage porosity. For this purpose, the simulation of finite element method was used. Simulation results were used to select the optimal ratio of the H/D, the number of polygon and the concave radius of the ingot to produce a new CH3C 80t ingot mould in Esfarayen Industrial Complex (EICO).

Effect recycled aluminium structures of metallurgycal and melt efficiency

Generally, an expired structure aluminum is recycled into raw materials for the next casting process or component products. Slag and aluminum left in the ladle caused low melting efficiency. Microstructure formed in the castings components solidification process is often used to control mechanical properties and the castings fabrication. The purpose of this study is to improve structure aluminum recycling process quality. This recycling study used structure aluminum raw materials with recycling levels variations in the 1st, 2nd, 3rd, and 4th. In the first recycling, the structure aluminum pieces as melting raw materials weighing 2 kg were put in the induction furnace for melting. Let the aluminum pieces melted in the furnace and the temperature continued to rise to 700°C. Next, separated and took the floating slag on top of liquid aluminum, lifted the ladle from the furnace and poured the aluminum in the ingot mold from the permanent mold. After the ingots in the mold were being frozen and cooled, removed the ingots from the mold to be weighed and tested for microstructure. In the second recycling, the melted raw material was the first recycling ingot with the same procedure. In the third recycle, the melted raw material was the second recycling ingot with the same procedure; and the third recycling, the raw material that was melted was the third recycling ingot with the same procedure. Then the slag and ingot was weighed, and microstructure photos from the ingots were taken. From the microstructural photographs results, a calculation process can be performed to determine the grain size of each specimen. For smelting efficiency testing results at each recycling stages respectively 1st, 2nd, 3rd, and 4th were 76.23%, 82.64%, 85.17%, and 89.55%. The largest microstructure diameter at the first recycling for the surface part was 42,512 µm and the center was 43,314 µm. The smallest grain diameter of the 3rd recycling for the surface part was 42,164 µm and the center was 42,346 µm.

Steel Ingot Mold’s Tapper Designing and Validation Based on Solidification Simulation

A 15t steel ingot, in which shrinkage cavity and porosity were often found during production, was analyzed by solidification simulation using casting simulation software. Position and size of the shrinkage porosity were predicted, agreed with dissection result very well. On the basis of solidification simulation, a series of new steel ingot molds were designed and the molds with preferable simulation results were selected for manufacture, which performed well in production.

Influence of the thermal factor on the composition of electron­beam high­entropy ALTiVCrNbMo coatings

This paper reports results of studying the element and phase compositions of electron-beam coatings based on the high-entropy alloy AlTiVCrNbMo, depending on the deposition temperature (in the range of 300...700 °С). The high-entropy alloys were melted in an arc furnace in an atmosphere of high-purity argon. Vacuum condensates of the high-entropy alloy (AlTiVCrNbMo) with a thickness of 3–5 µm were obtained in the vacuum setup UVN-2M-1 at a working vacuum of 5·10 -5 mТоrr. The alloy evaporation was performed from the water-cooled ingot mold using an electron-beam gun with a power of 5 kW. Condensation of vapors of all the elements of the alloy was performed onto copper substrates at temperatures of 300, 500, 700 °C. Based on analysis of the element composition of materials of the target made of the high-entropy six-element alloy AlTiVCrNbMo and electron-beam coatings, based on it, we established the critical parameter (specific heat of vaporization of an element) that defined a selective change in the element composition. In accordance with a characteristic change in the composition of coatings of the multi-element high-entropy alloy, 3 groups of elements were distinguished: with a specific heat of evaporation of 280...350 kJ/mol (group 1), 420…460 kJ/mol (group 2), and 590…680 kJ/mol (group 3). It was shown that the formation of a single-phase coating of the high-entropy alloy (based on BCC of the crystalline lattice) occurs at the higher deposition temperature of 500...700 °C when the coating consists of not less than 5 elements. It was established that based on the conditions for an electron-beam process of materials formation, the results obtained can be divided into two types: those determined by the condition of evaporation of the target and those determined by the conditions of coating deposition. The density of flows of elements, evaporated from the target, is determined by their specific heat of evaporation. However, the ratio of atoms in the flow, derived in this way, may not be retained in the formed coating due to the secondary evaporation of elements from the growth surface. The obtained results allow us to substantiate principles for the selection of components for achieving the optimal element and phase compositions of high-entropy alloys.

Experimental casting of forging ingots from model material

The paper describes the process of casting ingots from the model material into a special mold made for these tests. The material was chosen stearin, which proved to be suitable for this type of laboratory test. During the solidification process of the ingot model under laboratory conditions, it was observed how gradually the layer formed on the contour of the casting. Gradual cooling of the ingot resulted in a decrease in the volume of the liquid phase in his body. The fog is readily observable by the naked eye and this is manifested by the formation of a gap between the ingot mold wall and the ingot body. A silicone oil has been used as a separating melt separating layer and the wall of the ingot that has reliably fulfilled this task. Casting was done in two ways, with a standing and lagging mold. The process of filling the cavity itself was to create conditions for the linear flow of the melt. Observation of the ingot after its solidification confirmed the fact that the filling of the cavity proceeded under such conditions in terms of the melt flow rate.

The choice of ingot mould for manufacturing of hydrogen storage alloys in arc furnaces with permanent electrode

The choice of ingot mould for manufacturing of hydrogen storage alloys in arc furnaces with permanent electrode