The contract was administered under the technical supervision of r. The invention is directed to a flux for use in an electroslag refining process which adequately meets the necessary characteristics as set forth above. Metals free fulltext kinetics of phosphorus transfer during. Another timesaving benefit of the essc process stems from the electroslag refining that occurs when the molten metal passes through the slag bath.
The electroslag casting also called as electroslag remelting or electroflux remelting. Additional refining is usually performed by radiofrequency induction rfi melting under a slag layer. Such a homogeneous, directionally solidified esr ingot will be formed, free from central void spaces and. Predicting melting behavior of an industrial electroslag remelting ingot. The molten metal in the form if droplets is refined as it passes through the molten slag. Whether to include electroslag refining as a model. However, such phase was supposed to appear as a result of the refining process and at the same time the previously observed austenite phase disappeared completely. The slags in electroslag remelting esr process serve as a heat. Compared with the aluminum sample before electroslag refining, there is no obvious change on the contents of other impurity elements in the aluminum samples after electroslag refining. Esw is similar to electrogas welding, but the main difference is the arc starts in a different location. Electroslag remelting 2 20 ton esr furnace capable of melting under protective atmosphere.
Pdf the electroslag remelting process esr is important because it. The esr technology is of interest not only for the production of smaller weight ingots of tool steels and. Electroslag remelting furnaces for more information visit. Maraging steel, cobalt free, electroslag refining esr, surface tension, viscosity 1. In addition, it provides an ingot with dense structure free from inner porosity and holes. Computational modeling of the electroslag remelting esr. Process for electroslag refining of uranium and uranium. The carbon segregation was analyzed by original position analysis opa, and the carbides were analyzed by optical microscopy om, scanning electron microscopy sem. These two processes are known to affect to a great extent the homogeneity of the. A study of heat transfer and fluid flow in the electroslag. The result indicates that electroslag refining does not introduce new impurity element to the commercial aluminum after electroslag refining. Zero shear force is applied to the free surface of slag. The basic concept makes use of electroslag refining esr to melt and remove ceramic inclusions from the superalloy, com bined with an inductionheated, segmented, watercooled copper guide tube cig to deliver a stream of liquid metal to a spray forming atomizer.
Strip cladding has been around for decades, and historically, submerged arc strip cladding sasc has been the most commonly used process, offering deposition rates of about 33 pounds per hour. Electroslag remelting casting handbooks asm international. Each flux composition for the electroslag refining process covered by the invention utilizes bastnasite, a mixed rareearth fluocarbonate mineral, as an ingredient. Much higher levels of nitrogen can be achieved due to the pressure applied above the slag which can be increased significantly above normal atmospheric. By using the maraging steels at last three machining or. This thesis studies the possibilities of using lowcost air induction melting followed by refining using electroslag remelting esr for the production of ultrahighstrength, tough steel.
A process is described for electroslag refining of uranium and uranium alloys wherein molten uranium and uranium alloys are melted in a molten layer of a fluoride slag containing up to about 8 weight percent calcium metal. Electroslag refining or remelting esr has been used to produce cleaner steels with more uniform composition than conventional, even existing highquality, steels. The kinetic behavior of phosphorus transfer was investigated during electroslag remelting esr of g20crni2mo bearing steel. An improved electroslag refining esr flux composition and process for making same are shown. However, the productivity and efficiency gains that. Many properties of esr steels are dramatically superior to those of conventionally produced steels. Electroslag remelting esr is commonly used to produce the highest levels of quality in plate steels, particularly in thick plates. Electroslag remelting, rotating electrode, solidification structure, electrical behavior of rotating electrodes 1 introduction the electroslag remelting process esr is a refining process for metals used for special applications. Pdf electroslag refining of crnimowmnv ultrahighstrength steel. The bottom pour electroslag refining system comprises an electroslag refining crucible. Advantage of this process is that it has fewer steps than sand casting, has better control of the solidification microstructure and. It is also used to describe three separate processes, using the principle of electroslag namely i consumable electrode metal refining and cost structure improvement process ii the semicontinuous or 11. As a result of electroslag refining, the sulfur content in the metal can be lowered by a factor of 25, and the content of oxygen and nonmetallic inclusions can be lowered by a factor of 1. The properties of such materials depend mainly on the production technique as well as the refining technology.
Electroslag remelting its status, mechanism and refining. Front matter electroslag remelting and plasma arc melting. The method starts with the introduction of unrefined metal into an electroslag refining process in which the unrefined metal is first melted at the upper surface of the refining slag. Consumableguide welding is a much simplified version of electroslag welding. Electroslag welding an overview sciencedirect topics. Electroslag refining or remelting esr has been used to produce cleaner steels.
Electroslag remelting esr, also known as electroflux remelting, is a process of remelting and refining steel and other alloys for missioncritical applications in aircraft, thermal power stations, nuclear power plants, military technology, etc. Usually, after esr, the metal does not contain sany inclusion larger than 1012 mm. Oct 14, 2019 electroslag cladding provides alternative to standard cladding techniques. The electroslag refining process esr is a variant of the group of consumable electrode remelting processes esr, var, ebr and par for producing ingots of higher quality than that of the original material by means of controlled solidification and chemical refining.
Electroslag remelting an overview sciencedirect topics. Electroslag refining as a clean liquid metal source for. Flux for use in electroslag refining process lukens steel. Figure 1 shows a schematic diagram of the esr process that uses a stationary. The pressure electroslag remelting process is a recent advancement and allows for the manufacture of new high nitrogen alloys with unique properties under pressures of several atmospheres. Although electroslag welding is mainly used for the joining of mild and lowalloy steels, satisfactory welds have been made in highalloy steels, titanium and aluminium. Among the different refining processes such as vacuum arc remelting, electron beam remelting, plasma arc remelting and electroslag remelting, electroslag remelting esr process is considered as the most distinguished secondary refining process due to its reality, economical production cost, low needed investments, system with noncomplicated. Electroslag remelting esr, also known as electroflux remelting, is a process of remelting and refining steel and other alloys for missioncritical applications in aircraft, thermal power stations, nuclear power plants, military technology, etc the electroslag remelting esr process is used to remelt and refine steels and various superalloys, resulting in highquality ingots. The solidification of the molten steel into an ingot should be free from internal. O free of macrosegregation and reduction of microsegregation o high degree of cleanliness o remaining inclusions are very small in size and evenly spread oexcellent mechanical properties in transversal and longitudinal directions ofree of internal flaws e. Esr electroslag remelting is the abbreviated name given to electroslag consumable electrode remelting and secondary refining process. This article provides an overview of the esr and discusses the major components and operations of the esr furnaces. Investigation of fluoride evaporation from caf 2 caoal 2 o 3. Electro slag remelting furnace ald vacuum technologies.
Esr electroslag refining technology in australia laboratory. The effect of electroslag remelting esr on carbides in 8crmov martensitic stainless steel was experimentally studied. Applicated for several decades, this process can produce materials with a narrow chemical composition in. Welding guidelines specific welding guidelines will depend on the alloy being clad so preheat, interpass and pwht requirements should be applied for the material being clad. Many investigators argue that esr has an advantage over var because there are more parameters or degrees of free dom in the electroslag. Electroslag remelting article about electroslag remelting. The new ingot of refined material builds up slowly from the base of the crucible, homogeneous, and free from the central unsoundness that can occur in. Alds esr electroslag remelting has been known since the 1930s, but it took approximately 30 years before it. Copper electroslag remelting in the soviet and west. This process significantly reduces the sulphur content and the size of nonmetallic inclusions. A method of forming an ingot of refined metal by the electroslag refining process comprising the steps of introducing into the lower open end of a cooled mould a solid uncooled electricallyconductive member of a material weldably compatible with the metal to be refined, the member having a surface area sufficient to conduct the full working current employed in the process but.
Oct 01, 2009 the refining of titanium to remove nitrogen and oxygen in the metallurgical processing of titanium sponge into ingots by the conventional special electrometallurgy methods vacuumarc, plasmaarc and electron beam remelting has been studied in a relatively large number of investigations both in this country and abroad 15, so that it is possible to conclude that these processes can be used. The basic esr system consists of a consumable electrode of the alloy to be melted, a. Majority of inclusions are eliminated during esr depending on slag composition, temperature and melt rate. The calcium metal reduces oxides in the uranium and uranium alloys to provide them with an oxygen content of less than 100. Electroslag remelting esr, also known as electroflux remelting, is a process of remelting and. The ingot produced is characterized by a compact, ordered microstructure that is free. Nitrogen dissolves in the molten slag either in the form of free nitride n. Electroslag refining of crnimowmnv ultrahighstrength steel. In particular, the invention relates to a flux for such use which substantially precludes introduction of hydrogen into the resulting steel and at the same time maintains good desulfurization capacity. Us6350293b1 bottom pour electroslag refining systems and. Melting temperatures of some multicomponent local slags were found to be significantly higher than reported nominal values. The premelted slag possessing electrical conductivity is located on the watercooled mold base connected to a power supply. This simplification stems mainly from the use of a wire guide. Electroslag refining was selected because it is easy to scale up to the necessary industrial levels.
A bottom pour electroslag refining system refines raw material into refined liquid metal. It is also found that the ductility, impact toughness and. Investigations used a small experimental aboratory esr unit, and a large commercial unit manufactured by consarc. Electroslag remelting esr, refining, inoculation, quality steels.
An electric arc is initially struck by wire that is fed into the desired weld location and then flux is added. Us3857702a electroslag refining flux compositions and. The pressure electroslag remelting process pesr total. Phases precipitated from liquid steel during solidification were calculated using the thermocalc software. The refined metal droplets are collected in a cold hearth apparatus. Esr has been known since the 1930s, but it took approx. Refining reactions in applying the electroslag remelting technique successfully to superalloys an understanding of the potential re actions and refining mechanisms, is necessary, these may be divided for convenience into flotation or mechani cal removal and chemical and electro chemical reactions. A method of electroslag refining of metal is taught. A method of forming an ingot of refined metal by the electroslag refining process comprises the steps of introducing into the lower open end of a cooled mould a solid uncooled electricallyconductive member of a material weldably compatible with the metal to be refined, the member having a surface area sufficient to conduct the full working current employed in the process and being spaced. The invention relates to a flux composition used in the electroslag refining process. Such control reduces dendrite arm spacing, microsegregation, and porosity, hence leading to a sound ingot. Flux for use in electroslag refining process lukens.
It describes the principles of ingot solidification and various defects of remelted ingot such as. In order to use this method, special melting techniques had to be developed because of some anomalies of the refining process. Pdf electroslag remelting of high technological steels. In this work the yield of alloying elements and the removal. Electroslag remelting esr can effectively improve the cleanliness and compactness. Electroslag strip cladding offers some advantages when compared to its sasc counterpart, including a reduced dilution rate of base material into the weld typically about 10 percent for essc compared to 20 percent for sasc along with greater deposition rates, improved travel speeds and lower flux consumption. Designs and manufactures furnace systems for a variety of metallurgical processes, including. Pdf study of electroslag remelted and nitrogen containing. The instant esr flux compositions are made from particulate batch materials providing at least alumina, a fluoride and alkaline earth metal oxide, including calcium oxide, by the process described to yield a product exhibiting a substantially uniform fusion characteristic and to be substantially free. The electroslag refining esr process is one of the most important secondary refining processes owing to its relatively low production cost, low capital investment and ability to produce high quality steel with desired chemistry and homogenous structure.
Electroslag welding esw is a highly productive, single pass welding process for thick greater than 25 mm up to about 300 mm materials in a vertical or close to vertical position. Us5348566a method and apparatus for flow control in. Increasing demands for ultrahighstrength steels in commercial as well as military applications have raised interest in finding alternatives to the highcost highalloyed steel and superalloys currently used, e. Various thicknesses of iron and aluminum cylinders with uranium concentrations close to actual metallic wastes were melted by adding effective fluxes for decontamination. The three martensite phases were still appeared and showed more magnetic field intensities comparable to those appeared in samples if, m41 and ifn, m41. The electroslag remelting process esr is important because it provides better control of the solidification. Thinwalled iron and aluminum cylinders with a fill ratio electrodemold. Electroslag remelting of stainless steels in other.
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