Closure to discussions of the effect of vacuum arc. Consarc utilizes fully computerized controls to optimize reproducibility and ease of operation. State of the art in var and esr processes a comparison harald scholz, ulrich biebricher, henrik franz ald vacuum technologies, hanau, germany alberto paderni, paolo bettoni aso siderurgica, ospitaletto, italy abstract the increasing demands of modern manufacturing. Alternatively, in some processes, a reactive gas may be introduced into the process to become. There are several process variables which are crucial to the control of vacuum arc remelting of segregation sensitive alloys. Computational modeling of the vacuum arc remelting var process used for the production of ingots of titanium alloys kanchan m. State of the art in vacuum arc remelting and electro slag remelting process a comparison 1. Within the var furnace the copper mold is contained by a water jacket. The var process has revolutionized the specialty traditional metallurgical techniques industry, and has made possible incredibly controlled materials used in the biomedical, aviation, and aerospace fields. Computational analysis of the vacuum arc remelting var. Prediction of temperature in vacuum arc remelting in the presence. The most common remelting techniques for nickel alloys are vacuum arc remelting var and electroslag remelting esr. Exposure of molten metal droplets to vacuum reduces free gas content in the steel providing a cleaner product with little segregation.
Arc distribution and motion during the vacuum arc remelting process as detected with a magnetostatic approach. In vacuum induction melting vim a melting process that results. State of the art in vacuum arc remelting and electro slag. Vacuum arc remelting is a casting process where a consumable electrode is melted under vacuum at a carefully controlled rate using heat generated by an electric arc struck between the electrode and the ingot. In order to meet strict cleanliness specifications, ecfg has the capability to provide vacuum arc remelt var material. A parametric study of the vacuum arc remelting var process.
The var feedstock is consumable electrodes produced by vim or conventional air melting. It is has previously been shown that arcs can spatially constrict during var, and this constriction can lead to undesired defects in the material. Scale 3d model of the vacuum arc remelting process. The transient behavior of the arc was characterized using the external magnetic field and surface current measurements, which were. The final solidification structures of vacuum arc remelting var ingots depend on the temperature distribution and fluid motion within the molten pool. Var is the continuous remelting of a consumable electrode by means of an arc under vacuum. Remelting variations under vacuum apart from the remelting of a consumable electrode in a watercooled copper crucible, there is a recent development of the vacuum arc remelting process, namely vacuum arc double electrode remelting vader. For var, various process parameters could be analyzed using commercial modeling software to determine the best solution to resolve different types of problems, such as alloy segregation and shrinkage pipe. 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.
Each of the pumping units is switchable individually as well as in series. Vacuum arc remelting is the continuous remelting of a consumable electrode by means of an electric dc arc between the electrode and the base of a copper mold. Alternative, melting and refining steps include vacuum induction melting, vacuum arc remelting, electroslag remelting, and electron beam melting. Four state variables were used to develop a simple statespace model of the var process. Pdf vacuum arc remelting var is an industrial metallurgical process widely used throughout the specialty metals industry to cast. Intense heat generated by the arc melts the tip of the electrode while a new ingot is progressively formed below in. Large gun tube forgings are presently produced from staticallycast electric arc furnace steel ingots. Us92201b1 ingot solidification controller for vacuum.
A multiscale 3d model of the vacuum arc remelting process. Vacuum arc remelting furnace var ald vacuum technologies. Pdf modeling of the vacuum arc remelting process for estimation. As the melting electrode drips into the bottom of the vessel, the surface area of each falling drip is exposed to the environment of the vacuum, which removes any residual gases from the alloy. Vacuum arc remelting furnace, this is a consumable electrode remelting process performed inside a vacuum chamber. Electroslag remelting esr in this process, there is a slowly melting consumable electrode and a watercooled mold for solidification, as in vacuum arc remelting, but the melting is conducted under normal atmosphere and is accomplished by a thick, superheated layer of slag on top of the shallow metal pool. One advantage of the vacuum arc remelting process over vacuum induction melting, for instance, is better melting rate control. The purpose of vacuum metallurgy is to prevent contamination of metal by gases in the atmosphere.
Specifically, the model predicts the pool depth as a function of radial position from ingot centerline and time, given melting current, and electrode melting efficiency. A nonlinear reduced order model for estimation and control. Us3812899a controlled pressure consumable electrode. This article provides an overview of the studies on computational modeling of the vacuum arc remelting var and electroslag remelting esr processes. Vacuum arc remelting casting handbooks asm international. Graduate thesis or dissertation arc distribution and. Vacuum induction melting and vacuum arc remelting of coal. Pdf on the modeling of vacuum arc remelting process in. A method of modelbased ingot solidification control for the vacuum arc remelting process is presented. On the modeling of vacuum arc remelting process in. Introduction to stainless steels asm international. The vacuum arc remelting var process is widely used to improve the cleanliness and refine the structure of standard air melted or. The quality of the produced ingots depends on the operating conditions which could be monitored and analyzed using numerical modelling.
The primary motivation for characterizing arc motion and distribution inside a var furnace is to. A vacuum arc refers to an electrical discharge between a cathode and an anode at pressures low. The analysis leading to the model assumes that the electrode gap is being accurately controlled during the melting process. Vacuum arc remelting var and electroslag remelting esr are two secondary refining processes applied to conventionally produced steel.
Vacuum arc remelting is a widely applied vacuum melting process used to control the solidification of segregation sensitive alloys. This article illustrates the var process and the capabilities and variables of the var process. Vacuum arc remelting furnaces var consarc engineering. This paper describes process modeling applications of vacuum arc remelting var and plasma arc melting pam. Vacuum arc remelting var is an industrial metallurgical process widely used throughout the specialty metals industry to cast large alloy ingots. Currently, the temporal arc distribution across the ingot during the vacuum arc remelting var process is not a known or monitored parameter. An introduction to premium melting carpenter technology.
Other articles where vacuum arc remelting is discussed. Of these variables, active, closed loop control is usually applied only to electrode gap. Vacuum arc remelting var is a secondary melting process for production of metal ingots with elevated chemical and mechanical homogeneity for highly demanding applications. Vacuum arc remelting vacuum arc remelting var is another secondary refining process that enhances the quality of metal that had undergone primary air melting andor was melted, or remelted, in arc, vim or esr furnaces. Computational modeling of the vacuum arc remelting var. This report addresses a mechanical property characterization of a split argonoxygen decarburized aod heat of 4340 steel which was further processed by vacuum arc remelting var and electroslag remelting esr into 12. Modeling of the vacuum arc remelting process for estimation and control of the liquid pool profile article pdf available in journal of dynamic systems measurement and control 63. Tool steels cold and hot work steels for milling cutters, drill bits, etc. Ingots produced by air melting, esr, vim, and ebm are utilized as electrodes in the. Applications of finite element modeling on vacuum arc. View enhanced pdf access article on wiley online library html view download pdf for offline viewing. Experimental melts of 100 mm diameter ingots melted in a laboratory consumable arc furnace have been carried out to investigate the effect of melting variables. At higher pressures and longer gap lengths, however, scattering interactions with the relatively cold ambient gas begin to remove significant amounts of energy from the arc plasma, interfering with the.
Var steels and specialalloys, as well as titanium and zirconium and their alloys, are used in a large number of high integrity applications, where cleanliness, homogeneity and improved fatigue properties in the final product are essential. Arc distribution during the vacuum arc remelting of ti6al4v. Pdf modeling of the vacuum arc remelting process for. These models involve the axisymmetric analysis of the electromagnetic, flow, heattransfer, and phasechange phenomena to predict the pool shape and thermal history of an ingot using two. Both techniques are consumable electrode melting processes in which the heat is generated by an electric arc between the ingot electrode cast from the primary melting process and some type of base plate located at the bottom of.
It is most commonly the final liquid metal processing step before forging. Patankar1, alec mitchell2, osamu kanou3, nobuo fukada3, kenji suzuki3 1innovative research, inc. Var vacuum arc remelting 11 vacuum system intecos vacuum system is designed for utmost flexibility and minimized pump down times, which can be achieved by one threestage mechanical pumping unit and, for fine vacuum, one oil booster ejection unit. Var vacuum arc remelt matrial for cleanliness specifications. The vacuum arc remelting var process is widely used to improve the cleanliness and refine the structure of standard air melted or vacuum induction melted vim ingots and also used in the triplex production of superalloys. Manganese or other high vapor pressure elements are prevented from volatilizing during vacuum arc remelting by introducing a small flow of inert gas into the mold and varying the rate of exhaust of gases from the mold from a maximum value when the arc zone is at the bottom of the mold to a minimum value when the arc zone is at the top of the mold so as to maintain a pressure in the arc zone.
The var process is carried out in a vacuum with the aim of melting a large consumable electrode. A system for predictive, noninvasive temperature measurement in a broad class of manufacturing processes is presented. In this process, employed for casting steels that contain easily oxidized alloying elements, a consumable electrode made of forged steel or of compacted powder or sponge is continuously melted by an arc under vacuum. The first furnace, resembling furnaces in operation today, was built by vonbolten in 1903 noesen 1967. Fig ure 5 shows the basic design of the vader process with a static crucible. Rigel woodside for the degree of doctor of philosophy in mechanical engineering presented on june 4, 2010 title. Pdf a parametric study of the vacuum arc remelting var.
Experiments on the consumable vacuum arc remelting process. Vacuum arc remelting furnaces var vacuum aluminum brazing furnaces vab electroslag remelting furnaces esr induction skull melting furnaces ism. The main process stages o a consumable var electrode is generated by vim, esr, eb or plasma methods, assembled from titanium sponge, scrap or bulk, or by a prior var melt o dc power is applied to strike an arc between the electrode and the. Industry standard instrumentation, which includes electric current and voltage measurements, can asses the stability of an arc but cannot predict the location of an arc. Vacuum arc remelting furnaces var products consarc.
Modern control strategies for vacuum arc remelting of. Consult alds entire vacuum arc remelting var catalogue on directindustry. Vacuum arc remelting var ald pdf catalogs technical. Vacuum arc remelting furnaces var furnaces for melting material that have already been melted and cast into electrodes that are near their full packing density. Effects of arc radius, side arcing, and gas cooling article pdf available in metallurgical and materials transactions b 514. Var skull melter titanium casting titanium casting is increasingly selected as an economical manufacturing method for near net shaped components. Vacuum metallurgy is that field of materials technology that deals with making, shaping, or treating metals in a controlled atmosphere, at pressures significantly less than normal atmospheric pressure.
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