Production Of Ingots Research Articles

Structure and Properties of Titanium Modified Silicon-carbide at EBM

Aim of the work is development of technology of production of ingots from sparsely-alloyed titanium alloys using electron beam melting method. To get high mechanical characteristics in titanium alloy, the modifiers of high-dispersion carbide compounds were used as foundry alloys. They in process of electron beam melting provide strengthened with nanoparticles structure of a material suitable for further deformation processing. In order to develop nanosized alloying modifiers for high-strength titanium alloys there were synthesized nanosized powder in form of carbon solution in silicon-carbide. A technology was developed for production of ingots from sparsely-alloyed titanium alloys using electron beam melting method. The works on production of 200 mm diam. titanium ingots with addition of 0.5% and 1.5% of the alloying modifiers based synthesized nanosized silicon-carbide were carried out with the help of determined modes. Hot deformation processing of ingots was performed, 15 mm thick deformed sheets were produced and then subjected to further heat treatment. Structure and properties of obtained material were investigated.

Some Principles of Alloying of Aluminum Alloys with Scandium and Zirconium in Ingot Production of Deformed Semiproducts

Two principles of alloying are suggested for creation of aluminum alloys sparingly alloyed with scandium, which intensify the metastability of the process of crystallization in continuous casting of ingots. The first principle consists in keeping a one-to-one scandium-to-zirconium proportion, for example, 0.11% Sc and 0.11% Zr. The second principle consists in multicomponent alloying with transition and rare-earth metals, which intensifies the metastability of crystallization.

Production of high performance multi-crystalline silicon ingots for PV application by using contamination-free SixNy seed particles

In this work a new type of contamination-free SixNy seed particles for the directional solidification of HPM silicon ingots is introduced and evaluated. Several G1 crystallization experiments have been carried out to examine the influence of the seed particle size, the introduced mass and the influence of the composition of the underlying Si3N4 coating at the crucible bottom. Finally, multi-PERC cells over the ingot height from one of the most promising SixNy seeded ingot have been prepared.The results show that an oxygen contamination is not occurring by the new particles. A minimum seed particle density of around 120/cm2 at the crucible bottom is sufficient to generate a HPM like grain structure with random grain boundary fractions R of 65%±5%, which is very close to typical values of classical silicon seeded HPM. A further increase of the particle density doesn’t lead to a further increase of the R value due to the competition between the very close packed seeds.While lower oxygen levels of the Si3N4-coating promote significant higher R values in crucible setups without seed particles, the Si3N4-coating composition has almost no influence on the resulting grain structure properties when SixNy seed particles are used. This could be shown even for small seed densities of ~30 cm−2 and a remaining coating area fraction of 80%.The cell analysis shows same efficiencies of the ingots seeded on the SixNy particles and on the silicon feedstock layer, but a higher wafer yield can be achieved in the case of the SixNy seeding method since a full melt process can be used.

Improving Cylindrical Inconel 718 Ingots Produced at PAO Ruspolimet

Abstract—Analysis of the smelting and casting of cylindrical ingots of Inconel 718 alloy produced in a vacuum induction furnace at PAO Ruspolimet shows that existing technology does not ensure the production of a dense ingot of the required quality on account of porosity in the axial zone and segregation of elements such as chromium, nickel, and niobium. The results show that the casting and solidification of the Inconel 718 ingots must be corrected so as to obtain high-quality dense ingots, without changing the basic features of the production process: a 3-t vacuum induction furnace, a ceramic lining based on aluminum oxide (Al2O3), a cylindrical mold for ingots of diameter 410 mm, and a mold of diameter 450 mm for vacuum-arc remelting. By means of Thermo-Calc software (2017a version), the solidus temperature for equilibrium solidification (1211°C) and nonequilibrium solidification (1091°C) are refined. On the basis of the results, by computer simulation of the casting processes, the casting rate is corrected by decreasing the diameter of the casting nozzle from 32 to 28 mm and the casting temperature from 1470 to 1460°C. A batch of ingots is produced by the corrected technology. Transverse templates are taken from such a sample to determine the chemical composition, and longitudinal sections are taken for metallographic analysis. Metallographic data indicate decrease in porosity of the ingot’s axial zone and decrease in the segregation. On the basis of the results, the introduction of appropriate changes in the casting technology is proposed. Computer simulation of the casting and solidification processes permits the development of a technology in which high-quality ingots are produced in the first step. All of the products meet the customer requirements.

Cast Iron Smelting and Fining: An Iron Smelting Site of the Eastern Han Dynasty in Xuxiebian, Sichuan Province, China

In this article, we introduce the excavation of an iron smelting site at Xuxiebian 許鞋匾, Pujiang 蒲江 County, Sichuan 四川 Province in the PRC. Two excavations were carried out in 2007 and 2011, and a total of four bowl-shaped furnaces, five pits, two trenches, and one posthole were excavated. The site is dated from the mid-late Eastern Han dynasty to the Jin dynasty (ca. AD 150-420) according to the local pottery assemblage. It is possible that the sole functions of the Xuxiebian site were the production of pig iron ingots and the conversion of pig iron to wrought iron. The iron ingots were likely transported to areas with stronger administrative control by the central government near the ancient city of Chengdu or even to the Central Plains, where they were then cast into different objects.

Monitoring of an ingot making facility via principal component analysis and its variants

The ingots are a key intermediate product manufactured in the steel making industries. The article delves into the monitoring of the ingot manufacturing facility by making use of the multivariate process monitoring techniques. In order to deal with the various scenarios arising during the production of ingots, different variants viz. multi-block principal component analysis and multi-way principal component analysis are also employed to monitor the process and feed stock characteristics. A comparative analysis of the merits and demerits of the employed variants is also presented in the article based on the case study. On the basis of the findings it may be concluded that the decision regarding the methodology to be adopted depends upon a trade-off between the scope of application of the methodology and the ease of development.

Monitoring of an ingot making facility via principal component analysis and its variants

The ingots are a key intermediate product manufactured in the steel making industries. The article delves into the monitoring of the ingot manufacturing facility by making use of the multivariate process monitoring techniques. In order to deal with the various scenarios arising during the production of ingots, different variants viz. multi-block principal component analysis and multi-way principal component analysis are also employed to monitor the process and feed stock characteristics. A comparative analysis of the merits and demerits of the employed variants is also presented in the article based on the case study. On the basis of the findings it may be concluded that the decision regarding the methodology to be adopted depends upon a trade-off between the scope of application of the methodology and the ease of development.

Recycling of Dispersed Metal Wastes in Rotary Furnaces

The recycling of dispersed metal containing wastes is a considerable problem, as their accumulation in dumps today is commensurate with the volume of ore extraction. Several methods and technologies are developed to recycle metal containing wastes but almost all of them require the preliminary preparation of wastes resulting in an increased price of the recycled metals. Furthermore, it is especially difficult to recycle dispersed multicomponent wastes and, therefore, the problem of developing effective, flexible and reliable technology for recycling of dispersed metal containing wastes is still a pressing one. The article presents an alternative method of recycling dispersed iron-containing wastes based on a continuous solid-liquid process of iron oxides reduction in rotary tilting furnaces (RTF). The new method allows the processing of waste of almost any composition and state: from metal lumps to oxide and multicomponent (chips, scale, sludge, etc.) wastes, contaminated with moisture, oils, organic impurities without their preliminary preparation (cleaning, homogenization, pelletizing, etc.). The result of recycling is the production of cast iron or steel ingots or required casting alloys. Some features of technology are considered, including the gas flow and motion of charge metal particles within the RTF. Process parameters providing high metal output are established.

Emergy-based environmental accounting of gold ingot production in China

Gold production has brought serious environmental impacts on the natural ecosystem. Thus, it is critical to evaluate such impacts so that appropriate mitigation measures can be initiated. Derived from thermodynamics and systems ecology, emergy synthesis is one evaluation method widely used for environmental accounting. This study employs emergy-based indicators to evaluate gold ingot production based on regional data so that the holistic environmental performance of gold production in China can be examined. Sensitivity analysis on gold concentration, dominant contributors, labor & services is conducted so that more reliable results can be obtained. Results show that the total emergy (without labor & services) used for per gram gold ingot production was 9.63E + 13 sej, in which energy and chemicals were the dominant contributors. Specially, the unit emergy value of gold in the ground based on local gold enrichment was 3.67E + 12 sej/g. Results also indicate that gold production is extremely unsustainable because it’s heavily dependent on nonrenewable resources during its whole production life cycle. Finally, several recommendations were proposed to mitigate its overall environmental impacts by considering the local realities.

Processing Methods of Silicon to its Ingot: a Review

Any metal must be processed from its ore before employing it in various industrial applications; this is the similar case with Silicon (Si) as well. Occurring in the form of silicates in the earth’s crust, Si must be processed to achieve high purity for industrial applications. A major share of Si goes into the production of its wafers on which miniaturized circuits can be integrated and these wafers are also used in making solar cells. These wafers are produced by dividing Si chips into smaller parts, and the Si chips are produced by slicing Si ingots. Once the ingot is produced there is no scope to increase the purity of the Si, and the wafers will have purity less than or equal to the ingot purity and the solar cells produced will have equivalent conversion efficiency. Hence, the production of Si ingot plays a very crucial role at the back-end in determining the final purity of the wafer or efficiency of the solar cell. The pace at which the technology is developing today forecasts a huge demand of high purity Si wafers and alternate energy sources are also which in turn demands further increase in purity that makes the Si ingot production highly important. The present-day use of very large-scale integration techniques and the advancement towards the ultra-large-scale integration further makes Si chips foremost resourceful. The current review work aims to compile the capabilities of existing Si ingot production methods which are already employed in industries and production methods that are still being researched upon, and to present critical analysis which has been done to provide the method to be chosen to produce Si ingot based on application, production quality and quantity.

Influence of thermomechanical shrinkage on macrosegregation during solidification of a large-sized high-strength steel ingot

Finite element modeling (FEM) validated by experimental work was used to simulate the influence of thermomechanical shrinkage on macrosegregation of alloying elements in a large-sized ingot of high-strength steel. The full algorithms of the filling and solidification process for thermohydraulic and thermomechanic analyses were developed and implemented in the 3D FEM code Thercast®. Material properties were determined by a combination of experimental works, thermodynamic software Thermo-Calc®, a database, and literature source. It was predicted that thermomechanical shrinkage decreased the temperature gradients, advanced the initiation of solidification, and reduced the solidification time. The above changes resulted in less severe segregation along the centerline, in the zone next to the ingot surface, in the upper section of the ingot, and in the hot-top. Thermomechanic model predictions were proved to agree better with experimental results than the thermohydraulic one. The obtained results were interpreted in the framework of the theories on diffusion and solidification of alloyed systems. These findings contribute to a better understanding of the impact of thermomechanical shrinkage in ingot cooling process. They could also be used in industry to improve the quality of large-sized ingot production and the productivity of high value-added steels or other alloys.

Improving the Solidified Structure by Optimization of Coil Configuration in Pulsed Magneto-Oscillation

Using both numerical and experimental methods, we studied the effect of coil configuration of pulsed magneto-oscillation (PMO) on distribution of electromagnetic field, flow field and solidification structure with the same pulse current parameters in Al ingots. We designed and constructed three types of coils: surface pulsed magneto-oscillation, hot-top pulsed magneto-oscillation (HPMO) and combined pulsed magneto-oscillation (CPMO). PMO treatment refined the solidification structure in all the ingots. The configuration of the PMO, however, introduced differences in magnetic field intensity, electromagnetic force, Joule heat, flow field, equiaxed grain zone, grain size and growth direction of columnar grains. The largest equiaxed grain zone was found in CPMO treated ingot, and the smallest grain size was found in both HPMO and CPMO treated ingots. Numerical simulation indicated that difference in electromagnetic field and flow field resulted in differences in solidification structure. HPMO is more advantageous over others for large ingot production.

The effect of bulk nucleation parameters on the formation of macroscopic grain of the large-scale titanium slab ingot during EBCHM

ABSTRACTThe application of single electron beam cold hearth melting (EBCHM) to the production of large-scale rectangular titanium ingots has the potential to produce high-quality titanium strip coils and achieve significant cost reductions. In this study, multi-scale modelling of macroscopic grain formation in large-scale titanium slab ingots during EBCHM was carried out, by combining the finite element (FE) method on the macroscale with a cellular automaton (CA) model on the microscale. The effects of bulk nucleation parameters on the formation of macroscopic grains were studied, and the predictions arising from simulations were compared with experimental results. Based on the nucleation parameters that were investigated, the process parameters could be optimised during EBCHM to achieve a solidification structure favourable for rolling.

Trace element migration during UF4 bomb reduction: Implications to metal fuel production, worker health and safety, and nuclear forensics

Understanding the migration of trace contaminants during the production of U metal is vital for fabricating advanced nuclear fuels, for managing worker health and safety at foundry and processing facilities, and for advancing nuclear forensic science. A common method used to produce actinide metals is the bomb reduction of suitable U precursors. Here, we report the results of a series of experiments designed to quantitatively track the trace contaminants Th, Ca, and Mg through a bomb reduction of UF4 using a vacuum induction furnace. In this series, UF4 charges were doped with elemental Th at 0 (a blank), 1, 10, 100, and 1000 ppm Th/U. Following reduction, the metal ingot products and the associated slag and crucibles were individually digested and analyzed using inductively coupled plasma-mass spectrometry. The results show that Th fractionation occurred at all concentrations but was most significant, and near quantitative, in samples starting with Th concentrations below 100 ppm. Thorium was found to incorporate into the slag and crucible in roughly equal proportions during reduction. A significant amount of U and Ca migrated into the crucible walls, each correlating positively with the quantities of Mg migrating from the MgO crucible to the U metal product.

Influence of pulsed magneto-oscillation on microstructure and mechanical property of rectangular 65Mn steel ingot

The pulsed magneto-oscillation (PMO) technique has the potential to be applied in the production of heavy steel ingot. In order to confirm it and achieve more insights, the solidification of rectangular 65Mn steel ingot with the size of 220 mm × 220 mm × 1000 mm was investigated under the impact of PMO. Experimental results present that PMO treatment can remarkably refine the solidified microstructure of 65Mn steel ingot in comparison with the reference ingot without PMO. The application of PMO not only significantly reduces the grain size, but also promotes the morphology transition of equiaxed grains from well-developed dendritic structures to globular structures. And the resulted globular morphology is mainly due to the fact that the PMO-induced forced flow enhances the stability of crystal growth. As a consequence, the average tensile strength of as-cast samples is enhanced from 643.4 to 762.9 MPa under the application of PMO.

Production of Steel Ingots Without Zonal Chemical Inhomogeneity for the Billets of Parts of Power-Generating Units

We study the technological specific features of the production of steel ingots without zonal chemical inhomogeneity aimed at manufacturing the billets of various parts of power-generating units made of 15KhN3MFA and 15Kh2MFA steels. The technology of pouring in a vacuum is developed with regard for the results of the numerical analysis of the process of solidification of a steel ingot 13.56 tons in weight by using the Poligon system of automatized modeling of the pouring processes. In order to get high-quality ingots, steel was melted in an EAF-12 according to a special technology guaranteeing low contents of sulfur, phosphorus, nonmetallic inclusions, and hydrogen. The specific structural features of an ingot with a mean diameter of 922 mm and the ratio H/D = 2.05 are taken into account in the development of the technology of forging in a 3000-ton press. Forging is performed for billets 900 × 930 × 1200 mm in size with the axial channel located at the top of the billets. To avoid confusions, sulfur prints were made from the top and bottom surfaces of the billet. The investigations demonstrate that the sulfur prints are practically identical for both surfaces, and small separate sulfur inclusions are uniformly distributed. The macrostructure corresponds to the GOST-10243. The results of UT testing demonstrate that the billets of the parts contain no defects with an area greater than 5 mm2. The mechanical properties at temperatures 20°C and 350°C are practically identical and higher more than the requirements of normative documents by 15–20%. For the additional metallurgical quality examination of the metal, we manufactured a test shell with a height of 1100 mm, an outer diameter of 870 mm, and a wall thickness of 250 mm.

Effect of pre-oxidation of Si3N4 powders on the interaction between Si3N4 coating and molten Si

Si3N4 coating is widely used in the production of photovoltaic silicon ingots. This work investigates the influence of pre-oxidation of Si3N4 powders on the interaction between Si3N4 coating and molten Si based on sessile drop experiments. It is found that the surface tension and surface roughness affect the contact angle and accordingly wetting behavior. A new mechanism for the permeation of molten Si in Si3N4 coating is proposed, where the driving force for the permeation is provided by chemical reaction between SiO2 and Si instead of usual capillary force.

El poblado fortificado metalúrgico del Calcolítico Medio y final de Puente de Santa Bárbara (Huércal-Overa, Almería)

The fortified chalcolithic settlement in Puente de Santa Barbara (Huercal-Overa, Almeria), with 1.5 ha, located 3 km away from the Cerro Minado copper mines, and exploited at least during the Late Chalcolithic, presents copper ores, crucible smelting and melting debris such as slags, casting prills, reduction vessels and crucibles. 4% of all the ceramic fragments correspond to reduction vessel and crucible fragments, spatially distributed in the three excavated sectors and suggest the generalization of the metallurgy within the habitat. The percentage of metallurgical evidences could only be compared in the southeast of the Iberian Peninsula to the Copper Age settlements of Parazuelos (Lorca, Murcia) and Agua Amarga (Lorca, Murcia), another minor site of 0.25 ha. These data suggest the hypothesis of small settlements specialized in the production of tools or small metallic ingots made in rectangular crucibles during the Late Chalcolithic in the Southeast of the Iberian Peninsula.

Analysis of an Approach for Detecting Arc Positions During Vacuum Arc Remelting Based on Magnetic Flux Density Measurements

Vacuum arc remelting (VAR) is a melting process for the production of homogeneous ingots, achieved by applying a direct current to create electrical arcs between the input electrode and the resultant ingot. Arc behavior drives quality of the end product, but no methodology is currently used in VAR furnaces at large scale to track arcs in real time. An arc position sensing (APS) technology was recently developed as a methodology to predict arc locations using magnetic field values measured by sensors. This system couples finite element analysis of VAR furnace magnetostatics with direct magnetic field measurements to predict arc locations. However, the published APS approach did not consider the effect of various practical issues that could affect the magnetic field distribution and thus arc location predictions. In this paper, we studied how altering assumptions made in the finite element model affect arc location predictions. These include the vertical position of the sensor relative to the electrode–ingot gap, a varying electrode–ingot gap size, ingot shrinkage, and the use of multiple sensors rather than a single sensor. Among the parameters studied, only vertical distance between arc and sensor locations causes large sources of error and should be considered further when applying an APS system. However, averaging the predicted locations from four evenly spaced sensors helps reduce this error to no more than 16% for a sensor position varying from 0.508 m below and above the electrode–ingot gap height.

Effects of hot top pulsed magneto-oscillation on solidification structure of steel ingot

Achieving a uniform structure with few defects in heavy steel ingot is of high commercial importance. In this present work, in order to verify the potential of pulsed magneto-oscillation (PMO) applied in the production of heavy ingot, an induction coil was located at the hot top of the steel ingot to develop a novel technique, named hot top pulsed magneto oscillation (HPMO). The influences of HPMO on the solidification structure, macro segregation and compactness of a cylindrical medium carbon steel ingot with the weight of 160 kg were systematically investigated by optical microscope (OM) and laser induced breakdown spectroscopy original position metal analyzer (LIBSOPA-IOO). The results show that HPMO not only causes significant grain refinement and promotes the occurrence of columnar to equiaxed transition (CET) but also can homogenize the carbon distribution and enhance the compactness of the steel ingot. Therefore, HPMO technique has the potential to be applied in the production of heavy steel ingots on an industrial scale.