Round Ingots Research Articles

Processability and structural evolution of round ingots of Al – 2 % Cu – 2 % Mn alloy during forming

This paper looks at the processability of round ingots of Al – 2% Cu – 2% Mn alloy during pressing, radial-displacement rolling and drawing. As a result of pressing combined with cross rolling, 9 mm round bars were obtained, which were then rolled and drawn into 0.5 mm wire. The wire was examined in its initial state and after different regimes of annealing. The paper shows that the cast structure contains a small amount (<2 vol. %) of eutectic particles Al2Cu and Al15(Fe,Mn)3Si2, which ensures a good deformation plasticity at the relatively low temperature of 300 oC and enables to produce 15 mm pressed round bars with a 94% reduction. In spite of considerable strain hardening, the bars displayed high processability when subjected to cold radial-displacement rolling and drawing. Thus, a 0.5 mm wire could be obtained with a total reduction of 99%. Mn-bearing dispersoids partially formed during pressing, which prevent softening during annealing. It is shown that the best combination of strength and plasticity is achieved after annealing at 350 oC, which indicates a rather high heat resistance. This experimental alloy can potentially be used as a basis for developing wrought alloys designed to produce round ingots on a commercial scale. Such ingots require no homogenization and can be used to produce a variety of deformed semi-finished products offering an optimum combination of mechanical performance and heat resistance.This research was funded under Grant No. 20-19-00249 by the Russian Science Foundation.

The Structure and Properties of Wrought Al–Mg–Sc Aluminum Alloys with Different Scandium Content

Round ingots 110 mm in diameter and cold-rolled sheets 2 mm in thickness, which were made of experimental Al–Mg–Sc alloys containing different scandium content (0.07, 0.20 wt %), have been studied. Transmission electron microscopy and thermodynamic simulation have been used to investigate the peculiar-ities of the structural-phase state of the material. A reduction in scandium content from 0.20 to 0.07% has been found to result in a twofold increase in the grain size in ingots, a 46% drop in hardening of ingots after homogenization, and a 10–20% decrease in the strength of annealed sheets, which has been caused by a smaller amount of the key phase, Al3(Sc, Zr). A good level of strength characteristics of experimental annealed sheets made of alloy with low scandium content 0.07 wt % (σu 400 MPa, σ0.2 300 MPa) has been achieved and it is higher than that of the traditional AMg6 alloy (σu 350 MPa, σ0.2 150 MPa).

Conjugated Heat Exchange in Heat Treatment of Aluminum Ingots Simulation

Casting aluminum to obtain semi-finished products - round ingots, due to uneven cooling in the mold, leads to various defects that affect further machining. To eliminate such defects, heat treatment is carried out - homogenization annealing. One of the homogenization important stages is the cooling of the ingots after heating at a rate that does not lead to the ingot quenching. The cooling medium is air. Knowing the conditions of heat exchange between the cooling air and the high-temperature aluminum billet makes it possible to obtain the ingot’s necessary physical and mechanical properties. The article describes the developed mathematical model of conjugate heat transfer during homogenization annealing of aluminum ingot. It allows analytically calculating the temperature of the ingots depending on the cooling time. To verify the data obtained by the mathematical model, the conjugate heat transfer in the ANSYS program was simulated.

Evaluating the feasibility of applying cobalt-hydroxyapatite ingots as radiotherapy markers

The substitution of cobalt for calcium in hydroxyapatite produces CoHA with a higher effective atomic number. This study evaluates various medical imaging characteristics of round CoHA ingots in a porcine phantom to demonstrate the feasibility of using CoHA ingots as radiotherapy markers. CoHA was compressed into round ingots and then implanted into a porcine liver phantom and a gelatin porcine vertebra phantom along with three commercially available radiotherapy markers. The phantom was respectively scanned and photographed using a routine x-ray imager, magnetic resonance imager, computed tomography (CT) imager, and ultrasound imager followed by image analysis in ImageJ software. CoHA ingots could be clearly identified with general imaging instruments (x-ray, CT, and ultrasound) and the image size did not change. There were some metal artifacts in the magnetic resonance images. Biodegradable CoHA ingots can be self-absorbed by the body over time to avoid interference with follow-up disease screening and can be used with most medical imaging instruments quickly to help identify the location and extent of soft-tissue tumors.

Numerical Study on the Solid–Liquid Interface Evolution of Large-Scale Titanium Alloy Ingots During High Energy Consumption Electron Beam Cold Hearth Melting

In the present paper, a three-dimensional thermal-fluid multi-physical model has been established to investigate the effect of energy consumption operations on the evolutionary tendency of the solid–liquid interface for large-scale Ti-6 wt.%Al-4 wt.%V (TC4) round (Φ260 mm and Φ620 mm)/slab (1050 mm × 220 mm) ingots produced by electron beam cold hearth melting. The results qualitatively revealed the evolutionary tendency of the solid–liquid interface in different casting conditions, indicating that the solid–liquid interface with a gentle casting speed at a low pouring temperature will generate symmetric solid–liquid interfaces which were slightly affected by the modification of the pouring temperature. With an increasing energy input resulting from the rising casting speed, the deformation of the solid–liquid interface near the inlet was increased. As a result, the risk of breaking out and the formation of a non-uniform microstructure in the Φ620-mm round ingots and slab ingots was greatly increased.

Numerical study of aluminum segregation during electron beam cold hearth remelting for large-scale Ti-6 wt%Al-4 wt%V alloy round ingot

To investigate aluminum (Al) segregation in industrial-scale Ti-6 wt%Al-4 wt%V (TC4) round ingots produced by electron beam cold hearth remelting (EBCHR), a three-dimensional multiphysics model verified with experimental data in the literature has been established. The numerical predictions qualitatively reveal that the Al concentration distribution in the pool is highly related to the flow pattern. A promising method to restrain Al segregation is to enhance mixing during EBCHR by increasing the casting speed. A series of numerical cases reveal the relation between the casting speed, the dimensionless measure of the stirring intensity (Péclet number, Pe¯), and the corresponding segregation degree (Ф) in the pool. The results suggest that for EBCHR at a pouring temperature 2273 K, as the casting speed increases from 10 to 25 mm/min, the Pe¯ value increases from 418 to 1820, and the corresponding Ф value increases from 0.681 to 0.871. As a consequence, the intensity of aluminum segregation on the solidified cross-section improves (decreases from 2.77 × 10−3 to 1.76 × 10−4).

STATEMENT OF THE PROBLEM OF OPTIMIZING THE FACTORS OF THE HEAT EXCHANGE MODEL OF ALUMINUM INGOTS IN THE COOLING CHAMBER

Casting in a cooled mold is the main way to produce aluminum semi-finished products - round ingots. Continuous casting leads to the formation of a heterogeneous structure. Its elimination occurs during heat treatment - homogenization annealing followed by cooling in the chamber. To study the heat exchange between aluminum ingots and cooling coolant in the chamber, a mathematical model was developed. She showed that the cooling time of ingots in the chamber depends on structural and operational factors. This paper is devoted to the optimization of the design factors of the mathematical model of heat transfer in the cooling chamber of aluminum ingots. The questions of optimization criteria are considered, the objective function with restrictions on the set of feasible solutions of the function is defined.

Numerical Modeling of EBCHM for Large-Scale TC4 Alloy Round Ingots

The Electron beam cold hearth remelting (EBCHR) process has emerged as a key process in producing overlength TC4 round ingots. However, the quality of the ingots suffer from inhomogeneous composition segregation which is induced by improper operations. In the present study, a numerical model verified with experimental data from the literature was employed to investigate the finer details of EBCHM process. In order to track temperature evolution on the mold surface, heating by an approximating beam-pattern, user-defined function compiled with C code was added to the calculation. In addition, the evolution of the solid–liquid interface and melt-flow during EBCHM were also investigated under different operation conditions. The recommended pool morphology was found when the inlet velocity was 0.0295 m/s, the temperature of the inlet was maintained at 2173 K, and the mold surface was maintained at 1973 K. In those conditions, stirring inside the pool was strengthened to homogenize the composition, which may optimize the quality of the ingots.

Improved tension-compression performance of Mg-Al-Zn alloy processed by co-extrusion

Mg-3Al-1Zn round ingots were divided into several pieces and then cobbled together to introduce specific interfaces before direct extrusion. The microstructure, texture and mechanical response of the magnesium alloys processed by conventional extrusion and co-extrusion with introducing various interfaces were examined. The results indicated that the prewired various interfaces played important role on the microstructure evolution and texture modification of magnesium alloys during extrusion, and consequently influenced the tension-compression performance of the extruded alloys. Co-extrusion process by introducing appropriate interfaces during extrusion was suggested as a sample and effective method to enhance the comprehensive mechanical properties of Mg-Al-Zn alloys.

RESEARCH OF THERMAL MODES OF SOLIDIFICATION IN SEMI-CONTINUOUS CASTING ROUND STEEL INGOTS FOR THE PRODUCTION OF SEAMLESS TUBES

Authors studied the problem of obtaining high-quality semi-continuous round ingots of special steels in detail. There are the research data of solidification of round ingots in the graining pan and in the zone of with the development of two-phase zone in the first stage of the process of semi-continuous casting. On the basis of these data research, the search is conducted and conclusions about the modes f refrigeration in the zone of secondary refrigeration are described for obtaining the highest quality ingots with a view to possible further implementation of such mode in practice.

Shrinkage of Round Iron-Carbon Ingots during Solidification and Subsequent Cooling

The shrinkage of round iron-carbon ingots during solidification and subsequent cooling has been investigated with hot model experiments involving round ingots of 50 kg of steel. Three motor driven sensors made it possible to measure the shrinkage without deformation of the shell starting a few seconds after casting.The temperature distribution was computed with a thermal model. Thereafter, a mechanical model was applied to compute the shrinkage finding satisfactory agreement between the measured and computed shrinkage-time curves. Data are given on the effect of carbon content on the shrinkage of steel and it was confirmed that there is a shrinkage peak at about 0.1 mass% carbon.

The Han Period Round Ingots of Gold Unearthed at Tanjiaxiang in the Northern Outskirts of Xi‘an

The Han Period Round Ingots of Gold Unearthed at Tanjiaxiang in the Northern Outskirts of Xi‘an

Aluminum Evaporation from Titanium Alloys in EB Hearth Melting Process.

In order to investigate Al evaporation behavior in the EBCHR process, Ti alloys were remelted in a 250 kW EB furnace. Ti alloys used in this experiment were Ti-64, Ti-811 and SP700, a newly developed Ti alloy at NKK. In this experiment, EB power was kept almost constant and round ingots with approximately 136 mm in diameter were cast at a different casting rate. During melting operation, in-situ temperature measurement was carried out by a two-color thermometer. For determining an Al evaporation site in this process, both feedstocks and metal in the hearth after melting operation were analyzed in detail together with ingots.It was found that the Al yield, the ratio of the final Al concentration to the initial Al concentration, increased with the casting rate. Under the present experimental condition, the Al evaporation reaction took place mainly in the hearth, which was found to be a complete mixing reactor.Based on the above experimental results, the rate equation of Al evaporation was considered by taking account of both reaction at the interface and mass transfer in the melt. Calculation explained the experimental results well when the time-averaged temperature in the hearth was in the range of 1 800 and 1 900°C, which was in a relatively good agreement with temperature measurement results.

Mechanizing the centering of round ingots

Mechanizing the centering of round ingots

Decrease of residual stresses in ingots of aluminum alloys

1. We determined the distribution of residual stresses in round ingots occurring during casting of the ingots. 2. The cooling rate and the ductility of the alloy are the principal factors in the magnitude of the residual stresses occurring during casting. 3. Residual stresses in ingots decrease with decreasing amounts of silicon. 4. Annealing at 300°C for 4 h completely eliminates the residual stresses in ingots of the V95 alloy, 540 mm in diameter.