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. By varying the ratio of oxygen and argon, it is possible to remove carbon to controlled levels by oxidizing it to carbon monoxide without also oxidizing and losing expensive. Aod abbreviation stands for argon oxygen decarburization. Argon oxygen decarburization aod we supply industrial gases, related equipment, and services to steel manufacturers for argon oxygen decarburization aod. Argon oxygen decarburization aod is a process primarily used in production of stainless steel and other high grade alloys such as silicon steels, tool steels, nickelbase alloys and cobaltbase alloys with oxidizable elements such as chromium and aluminum. The advent of the argon oxygen decarburization aod process in stainless steel making resulted in an increase in south africas market share in stainless steel. 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. Argon oxygen decarburization aod is a process primarily used in production of stainless steel and other high grade alloys such as silicon steels, tool steels, nickelbase alloys and cobaltbase.
To avoid premature contact of oxygen with molten metal and ensure protection of the tuyere and the working chamber by the gas flow against. Optimization of the ao stainless steel processing cost by. Refractory wear increases at a rate proportional to the increased production rate when watercooled panels are not used. 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. Metals steel making argon oxygen decarburization aod. Metal refining with argon oxygen decarburization aod. Electric arc furnaces and argonoxygen decarburization. Translation find a translation for argon oxygen decarburization in other languages.
By using only eaf for the production of stainless steel the following difficulties were arise. Modeling of the vacuum oxygen decarburization refining. Gas supply modes include bulk deliveries, cylinders and onsite production units operated by air liquide. Several parameters come into play deciding the outcome of the process. A comparison study on depth of decarburization and the. It was inevitable that these furnaces contained oxygen and decarburization of the steel surface occurred. Two industrial vod nozzles were numerically studied and compared at different temperatures and ambient pressures. The vessel containing the steel melt is dried, as well as the cooling gas to the tuyere.
Aod has a top lance for oxygen injection and several bottom tuyeres for blowing oxygen or inert gas during the operation. In the aod process, steel from the eaf is transferred into an aod vessel and gaseous mixtures containing argon and oxygen or. You may do so in any reasonable manner, but not in. Decarburization basics arburization occurs when cardec bon atoms at the steel surface interact with the furnace atmosphere and are removed from the steel as a gaseous phase18. 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.
When refining stainless steel, inert gasesar, n2 are blown in at the same time as oxygen is under standard atmospheric pressure. Vertical integration as a source of competitiveness. This file is licensed under the creative commons attributionshare alike 2. This ingot refining process produces steel with low carbon properties. This argon dilution minimizes unwanted oxidation of precious elements contained in specialty steels, such as chromium. Kth optimization of the ao stainless steel processing cost by the ut as system chay tauar 800521t290 the argon oxygen decarburization aod process is one. Pdf simulation of fluid flow and oscillation of the.
The key feature in the aod vessel is that oxygen for decarburization is mixed with argon or nitrogen inert gases and injected through submerged tuyeres. Since stainless steels need to be further refined, oxygen, gradually replaced by argon, is blown through the molten steel to eliminate impurities. These blends, typically 1, 2 or 5% oxygen, provide good arc stability and very low levels of spatter and fume. In the aod process, steel from the eaf is transferred into an aod vessel and gaseous mixtures containing argon and.
Through the management of an additional high oxygen partial pressure gas mix and argon, the metal is refined and can reduce carbon levels to 0. Our applications engineers can help you determine the proper flow and pressure control needed for each gas to help you achieve consistent results and optimal. Argon oxygen decarburization aod is a process primarily used in steelmaking foundries and other highgrade alloys with oxidizable elements such as chrome and aluminum. Optimization of the ao stainless steel processing cost by the ut as system chay tauar 800521t290 the argon oxygen decarburization aod process is one of the major stainless steel refining routes. 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. Aod, argon oxygen decarburization, refining provides tight chemistry control and high levels of metal purity for your application. Abstract of ep0087328 a process to produce lowhydrogen steel by oxygen decarburization. Other articles where vacuum oxygen decarburization is discussed. Decarburization definition of decarburization by the.
In this process the tuyeres are submerged, resulting in high element recovery, rapid and efficient desulfurization, and good control of the slag chemistry. Argon oxygen decarburization aod and continuous casting cc steelmaking slags, with calcium oxide contents of 56. The latest advances made by the author with his research group have been summarized. Argonoxygen decarburization aod what a process for further refinement of stainless steel through reduction of carbon content. The analysis of the blowing process with the top lance of. In a controlled trial, 7 samples were decarburized and results measured for both low oxygenlevel atmospheres and air table 1. Why the amount of carbon in stainless steel must be lower than that in carbon steel or lower alloy steel i.
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. Vacuum oxygen decarburization metallurgy britannica. Argonoxygen blends are mostly widely used for conventional and pulsed spray transfer on clean little or no scale or residual oil, plain carbon and stainless steel. Modeling of gas flows in steelmaking decarburization. Our applications engineers can help you determine the proper flow and pressure control needed for each gas to. This introduction causes significant agitation and, therefore, intimate slagmetal contact. Water modeling was used to investigate the fluid flow and mixing characteristics in the bath of an 18 t aod vessel, as well as the backattack. The vod is often used to lower the carbon content of highalloy steels without also overoxidizing such oxidizable alloying elements as chromium. Metal refining with argon oxygen decarburization aod refining systems allow precise gas manipulation to achieve the desired end result. Vertical integration occurs when two firms that merge produce output or supply services that are used in successive stages of production weiss1992. Contributing factors are high temperatures and large amounts of oxygen in the atmosphere. Mathematical modeling of the argon oxygen decarburization. The new source performance standards nsps for steel plants.
The applications of the singlehole top lance, the 110threeholes top lance and the 150threeholes top lance in the speed of the decarburization are compared. What is called argon oxygen decarburization aod process. Argon oxygen decarburization converter aod tuyer pipe. Decarburization is a loss of carbon in the surfaceadjacent zone of the material gunnarson, 1963. Decarburization is a surface degradation phenomenon in the forging and heat treating of steels. In an aod, metal is subjected to three steps of refining. Electric arc furnaces and argon oxygen decarburization vessels were proposed on october 21, 1974, promulgated on september 23, 1975, and mostrecently amended on february 22, 2005. Needs very high temperatures about 19000 c for decarburization requiring high cost refractories. Air separation into oxygen, nitrogen, and argon background the purification of various components of air, in particular oxygen, nitrogen, and argon, is an important industrial process. In the argonoxygen decarburization process, a mixture of oxygen and argon gas is injected into the liquid steel. Argon oxygen decarburization aod air liquide supplies industrial gases and related equipment and services to steel manufacturers for argon oxygen decarburization aod.
Argon argonoxygen decarburisation air products offers a full line of industrial gases, including nitrogen and argon to assist with your argonoxygen decarburisation aod operations. 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. A dynamic model for the vacuum oxygen decarburization vod refining process is presented. Argonoxygen decarburization air products offers a full line of industrial gases, including argon, nitrogen and argon to assist with your aod operations.
An aspect of the present disclosure may provide an argon oxygen decarburization aod refining method for molten austenitic stainless steel and, more particularly, to an argon oxygen decarburization aod refining method capable of reducing carbon and nitrogen in molten austenitic stainless steel in aod refinement. The argon oxygen decarburization aod process is used to make stainless steel and specialty grades of steel, including tool steels, silicon steels, lowalloy steels, and lowcarbon steels. The oscillation of argon oxygen decarburization aod converters is flow related and depends on the process parameters e. After initial melting the metal is then transferred to an aod vessel where it will be subjected to three steps of refining. Decarburization article about decarburization by the. Aod is a kind of smelting equipment where final deoxidization and alloying of liquid steel take place. The amount of the chromium oxidized, and the temperatureincreasing speed of the bath is analyzed. When regal cast was established, the company installed an argon. What is the abbreviation for argon oxygen decarburization. Argon, nitrogen and oxygen for specialitystainless argon. A new method is used to calculate the oxygen distribution in the metalgas reactions. Modeling of the vacuum oxygen decarburization refining process.
Aod refining argon oxygen decarburization metaltek. Aod provides an economical way to produce stainless steel with a. Today, over 75% of the worlds stainless steel is made using the argon oxygen decarburization aod process invented by praxair. 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. A feasibility study is to be performed to investigate the possibility of producing 1500 metric tons per day of 99.
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