Argon oxygen decarburization aod converter is popularly used in the stainless steel making process. Ladle service under the conditions of vacuumoxygen. Argon oxygen decarburization furnace steel slag aod youtube. Due to the reduced co partial pressure under vacuum conditions, decarburisation of highalloyed steel grades to very low carbon contents is possible. Other articles where vacuum oxygen decarburization is discussed. Eaf followed by refining by argon oxygen decarburization aod to adjust the carbon content and remove impurities. Needs very high temperatures about 19000 c for decarburization requiring high cost refractories. Modeling of gas flows in steelmaking decarburization. The plant requires an efficient vacuum pump system to meet the specific requirements of the. Pdf a dynamic model for the vacuum oxygen decarburization vod refining process is presented. Decarburization is a classic surface degradation phenomenon in the forging and heat treating of steel. Ep0884a1 method of vacuum decarburizationrefining of. Electric arc furnaces and argonoxygen decarburization vessels in.
Control of decarburization of steel paul shefsiek introduction historically, heating steel for forming, forging or rolling, was done in electrical resistance or natural gas heated furnaces. At the same time, steel plants operate under the increasing pressure to design their processes more energyefficient and reduce co2 emissions drastically. Free ferrite layer depth ffd, when present and partial decarburization depth pdd, when free ferrite is understanding and measuring decarburization understanding the forces behind decarburization is the first step toward minimizing its detrimental effects. To be carried out accurately, the process depends on the ability to measure the composition of the stream of gas leaving the furnace throughout the process.
The currently available numerical models give an insight into process. Freeferrite layer depth ffd, when present and partial decarburiza. The carrying out of metallurgical reactions in the ladle is a common practice in practically all steelmaking shops, because it is costefficient to operate the primary furnace as a highspeed melter and to adjust the final chemical composition and temperature of the steel after tapping. Aod has a top lance for oxygen injection and several. Decarburization normally takes place when steel goes through the heating process in an environment where oxygen is present, resulting in loss of carbon and oxidation. Ladle service under the conditions of vacuum oxygen decarburization 187 a were mainly wom in the slag line. Established in the year 1996, we, pooja machines manufacturing private limited have gained immense expertise in the process of manufacturing and supplying a wide range of best quality air pollution control system the offered range has been availed to the major client base as per their requirements. Modeling of the vacuum oxygen decarburization refining process. In a straight barrel type vacuum refining apparatus, use is made of a combination of.
The argon oxygen decarburisation aod and the vacuum oxygen decarburisation vod processes are the. The processes can be combitype such as duplex or triplex ones. Argon oxygen decarburization furnace steel slag aod. Oerlikon leybold vacuum obtains atex certificate for steel degassing vacuum systems in recent decades, the demand for higherquality, refined steels has increased steadily. Modeling of the vacuum oxygen decarburization refining. Vacuum oxygen decarburization vod what process for further refinement of stainless steel through reduction of carbon content. Introduction to stainless steels asm international. Aod is a kind of smelting equipment where final deoxidization and alloying of liquid steel take place. Contributing factors are high temperatures and large amounts of oxygen in the atmosphere.
Argon oxygen decarburization aod is a process primarily used in stainless steel making and other high grade alloys with oxidizable elements such as chromium and aluminum. They were followed in the mid1960s by additional processes such as vacuum arc degassing, the aseaskf process, and the vacuum oxygen decarburization process for high chromium steels. Argon oxygen decarburization aod treatment is the recognized standard for stainless steel refining worldwide. Argon oxygen decarburization aod is a process primarily used in stainless steel making and other high grade alloys with oxidizable elements such as. The bath surface and the surface both of the injected ar gas bubble and co gas bubble formed inside the bath are considered as the. Oerlikon leybold vacuum obtains atex certificate for steel. The izhstal plant has created a technology for treating corrosionresistant steel by the method of vod in a 30ton ladle.
The plant is basically designed as a tank degassing plant which is additionally equipped with an oxygen blowing lance and other related equipment. Decarburization is not only dependent on the presence of oxygen but also the interaction with other oxidizing gases in the atmosphere, most notably water vapor and carbon dioxide. Alternative, melting and refining steps include vacuum induction melting, vacuum arc remelting, electroslag remelting, and electron beam melting. The effect of the process parameters and lining patterns on the endurance of the ladle was studied in development of the process.
The erosion of this zone amounted to 20 mm per heat. States are free under section 116 of the act to establish even more stringent emission limits than those. The lining of the ladle is made of periclasechromite refractories produced by the magnezit works jsc. This program has measured the decarburization of 300m alloy steel, as a function of temperature and oxygen concentration, and evaluated the results by way of models based on diffusion of carbon and on the effects of oxidation. Decarburization or decarbonization is the process opposite to carburization, namely the reduction of carbon content the term is typically used in metallurgy, describing the reduction of the content of carbon in metals usually steel. Argon oxygen decarburization, frequently referred to as aod, is an advanced. The formed carbon oxides can go into the atmosphere through the cracks in the oxide layer, while oxygen has free access to the steel surface. Understanding and measuring decarburization asm international. Decarburization is a surface degradation phenomenon in the forging and heat treating of steels. Melting and refining of stainless steels is, however, most frequently. At higher temperatures, the diffusion rate of carbon is so large that longer annealing times lead to decarburization. Learn more about praxairs argon oxygen decarburization process that is used to make over 75% of the worlds stainless steel.
Product program for efficient secondary metallurgy. The length of the blow period is determined by the starting carbon and silicon levels decarburizatoin the hot metal charged to the aod argonoxyge. Zhili song modeling of gas flows in steelmaking decarburization processes. Step 3either electroslag remelting esr, electroflux remelting efr or vacuum arc remelting var. Decarburization is prevented for brazing medium or highcarbon parts, decarb caused by excessive dew point can be a major problem. Review on cfd simulation and modeling of decarburization. Evaluation of the chemical vacuum effect in decarburization treatment by argoninjected steel under normal atmosphere. Why the amount of carbon in stainless steel must be lower than that in carbon steel or lower alloy steel i. Surface decarburization of the hypoeutectoid carbon steel c45. An argon oxygen decarburization aod refining method for molten austenitic stainless steel.
The decarburization step is controlled by ratios of oxygen to argon or nitrogen to remove the carbon from the metal bath. Vodc vacuum oxygen decarburization converter process. This process permits the production of high chromium steels and alloys in a technically and commercially advantageous way extremely low carbon contents together with high chromium recovery, with minimal consumption. When refining stainless steel, inert gasesar, n2 are blown in at the same time as oxygen is under standard atmospheric pressure. By using only eaf for the production of stainless steel the following difficulties were arise. Innovations in refining process technique combined. It is based on a stepwise comparison of the reaction free energies, and it allows the continuous calculation of the change of the metal, slag, and gas composition throughout the duration of the vod process. The vod is often used to lower the carbon content of highalloy steels without also overoxidizing such oxidizable alloying elements as chromium. Also, certain metallurgical reactions, for reasons of equipment design and. View enhanced pdf access article on wiley online library html view download pdf for offline viewing. Practical model to simulate and to operate vacuum oxygen decarburization vod plant for stainless steelmaking. Therefore, it is valuable to study not only the effect of temperature on depth of decarburization, but also the affect that stable carbide forming and additional alloying elements have on the decarburization response of a particular alloy. After initial melting the metal is then transferred to an aod vessel where it will be subjected to three steps of refining.
A dynamic model for the vacuum oxygen decarburization vod refining process is presented. In a controlled trial, 7 samples were decarburized and results measured for both low oxygen level atmospheres and air table 1. Decarburization may be eliminated by heating in furnaces with a protective atmosphere or under vacuum. There are various vessel stirring methods for making stainless steels aiming at usage of least cost charge materials, significant alloy. Argon oxygen decarburization for metal production praxair, inc. We have a wide variety to offer in order to cater to the variegated needs of our customers. Vacuum oxygen decarburization metallurgy britannica. Vacuum oxygen decarburization vod vacuum oxygen decarburization vod is the manufacturing process by which the quality of stainless steel is assured.
Vacuum oxygen decarburization vod of stainless steel. Thus, the fluid velocity by twoway coupling model is greater than that by oneway coupling model near the free surface of the vacuum chamber. Feel free to browse around to learn more but if you have questions or need to submit an rfq, please contact us. Modeling of gas flows in steelmaking decarburization processes zhili song doctoral thesis. Decarburization is a loss of carbon in the surfaceadjacent zone of the material gunnarson, 1963. Vd and vdob tank degassers, vod vacuum oxygen decarburization units. Step 2either argon oxygen decarburization aod, vacuum oxygen decarburization vod or vacuum degassing.
What is the abbreviation for vacuum oxygen decarburization. A comparison study on depth of decarburization and the. D this process is mainly used for making stainless steel only of 304l, 316l grade to achieve extra low carbon content in stainless steel. A mathematical model for nitrogen desorption and decarburization reactions in vacuum degasser was developed. Step 2either argon oxygen decarburization aod vacuum. Decarburization may be described as a metallurgical process in which the surface of steel is depleted of carbon, by heating above the lower critical temperature or by chemical action. By 1960, more efficient vacuum degassing methods such as the dortmund hoerder dh and ruhrstahlheraeus rh methods became popular. Decarburization article about decarburization by the. Through the management of an additional high oxygen partial pressure gas mix. Smajor ingredient responsible for the corrosion resistance. Download pdf 812k download meta ris compatible with endnote, reference manager, procite, refworks. After 3 4 heats, through slots formed in the joints of the bricks as well as ovalshaped washouts through which the metal leaked between the functional and the intermediate layer. Vod vacuum oxygen decarburization meltshop365 vod intelligent process automation for vod systems meltshop365 for vod plant ensures reproducible and documented quality and efficient and ergonomic use of resources through intelligent process automation.
Resourcesaving operation of stainless steel refining in vod and. Vod abbreviation stands for vacuum oxygen decarburization. Pdf practical model to simulate and to operate vacuum. Argon oxygen decarburization, frequently referred to as aod, is an advanced technology for the refinement of iron, nickel, and cobalt based alloys. Twoway coupling calculation for multiphase flow and. Electric arc furnaces and argonoxygen decarburization. Environmental protection agency office of air, noise, and radiation office of air quality planning and standards research triangle park, north carolina 27711. The aod process argon, oxygen, decarburization is the first production process for stainless steel. Electric arc furnaces and argon oxygen decarburization vessels in steel industry background information for proposed revisions to standards emission standards and engineering division u. It was inevitable that these furnaces contained oxygen and decarburization of the steel surface occurred. Today, over 75% of the worlds stainless steel is made using the argon oxygen decarburization aod process invented by praxair.
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