Aod provides an economical way to produce stainless steel with a minimal loss of precious elements. During heat treatment of metals, decarburization happens as a side effect, which is undesirable. Kinetics of decarburization reaction in oxygen steelmaking. Aod refining argon oxygen decarburization metaltek. Our soudoxar lance heads are equipped with laminar flow technology and are the fruit of advanced design and highquality production, to improve. Argon oxygen decarburization aod is a process primarily used in steelmaking foundries and other highgrade alloys with oxidizable elements such as chrome and aluminum. Needs very high temperatures about 19000 c for decarburization requiring high cost refractories. Decarburization definition of decarburization by the free. May 08, 2017 today, over 75% of the worlds stainless steel is made using the argon oxygen decarburization aod process invented by praxair.
It is inevitable that the furnace atmosphere contains oxygen. Argon oxygen decarburization furnace steel slag aod. Aod process was first used exclusively for stainless steel production. 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. Worlds largest argon oxygen decarburization aod unit, 175 ton capacity twin station ladle metallurgy furnace two doublestrand continuous casters slab reheat furnaces and slab conditioning facilities fivestand hot rolling mill anneal and pickle lines electric box annealing furnaces two tandem cold rolling mills. It was inevitable that these furnaces contained oxygen and decarburization of the steel surface occurred. It is normally used for deep decarburization of ighalloy steel grades usually to remove carbon without affecting chromium content in the production of. Recovery of valuable metals from argon oxygen decarburization aod dusts by leaching, filtration and solvent extraction. Invesitigation of air entrapment into an argon oxygen decarburization converter at the reduction stage yong tang timo fabritius and jouko harkki laboratory of process metallurgy, university of oulu, fin90014, finland abstract some argon oxygen decarburization aod converter workers found the nitrogen content in the low nitrogen. The argonoxygen decarburization aod process is the most common process for refining stainless.
The chemical composition of steel m0 is approximately fe0. Jun 01, 2018 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. 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. Today, over 75% of the worlds stainless steel is made using the argon oxygen decarburization aod process invented by praxair. A mathematical model for reactions during topblowing in. Argon oxygen decarburization converter aod tuyer pipe. Argon oxygen decarburization aod is a process primarily used in stainless steel making and.
Argon oxygen decarburization aod what a process for further refinement of stainless steel through reduction of carbon content. This ingot refining process produces steel with low carbon properties. The argon oxygen decarburization process total materia article. The reaction between carbon and the atmospheric gases usually begins around 700c 1292f. Argon oxygen decarburization aod is a decarburizatikn primarily used in stainless steel making and other high grade alloys with oxidizable elements such as chromium and aluminum. Optimization of the ao stainless steel processing cost by.
Several parameters come into play deciding the outcome of the process. 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. This introduction causes significant agitation and, therefore, intimate slagmetal contact. Decarburization is a classic surface degradation phenomenon in the forging and heat treating of steel. All structured data from the file and property namespaces is available under the creative commons cc0 license. Obtained 1045, and steel placed in furnace at 1700 deg. 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. The vod is often used to lower the carbon content of highalloy steels without also overoxidizing such oxidizable alloying elements as chromium. Electric arc furnaces eafs and argonoxygen decarburization. Why the amount of carbon in stainless steel must be lower than that in carbon steel or lower alloy steel i. Invented in the late 1960s, praxairs proprietary argon oxygen decarburization. A dynamic model for the vacuum oxygen decarburization vod refining process is presented. Rhamdhani swinburne university of technology, hawthorn, vic 3122 australia key words. Files are available under licenses specified on their description page.
A new method is used to calculate the oxygen distribution in the metalgas reactions. In this process the tuyeres are submerged, resulting in high element recovery, rapid and efficient desulfurization, and good control of the slag chemistry. By using only eaf for the production of stainless steel the following difficulties were arise. Argon oxygen decarburization aod converter is popularly used in the stainless steel making process. This page was last edited on 16 august 2018, at 20. Optimization of the ao stainless steel processing cost by the.
If decarburization is occurring, then a continuous surface layer of soft ferrite is being produced together with ferrite formation around austenite grains further away from the surface. 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. Decarburization occurs if carbon atoms in the heated steel component have both a a mechanism for migrating and b a desire to migrate to the surface. Theres even an industry standard astm e1077 dedicated to decarburization depth measurement. The removal of carbon removes hard carbide phases resulting in a softening of the metal, primarily at the surfaces which are in contact with the decarburizing gas. 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. Argon oxygen decarburization aod harbisonwalker international.
The mathematical model proposed and presented in part i of the present work has been used to deal with and analyze the austenitic stainless steel making i. Aod argon oxygen decarburization soudobeam has developed a range of oxygen and inert gas topblowing products in stainless steelmaking, for aod argon oxygen decarburization converters. Aod abbreviation stands for argon oxygen decarburization. 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. What links here related changes upload file special pages permanent link page.
The plant is basically designed as a tank degassing plant which is additionally equipped with an oxygen blowing lance and other related equipment. In the argonoxygen decarburization process, a mixture of oxygen and argon gas is injected into the liquid steel. Pdf the oscillation of argon oxygen decarburization aod converters is flow related and depends on the process parameters e. Decarburization was controlled by dissociative adsorption of oxygen. What is the abbreviation for argon oxygen decarburization. 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. 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. Jul 10, 2017 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. Due to the reduced co partial pressure under vacuum conditions, decarburisation of highalloyed steel grades to very low carbon contents is possible. 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. Argon oxygen decarburization furnace steel slag aod mineralproducts1. The installation of a lance and introduction of oxygen in the early stages of decarburization can reduce the time for a heat. The new source performance standards nsps for steel plants. The effect of flow rate of oxygen on decarburization rate, decarburization time, and total oxygen consumption was determined.
What is called argon oxygen decarburization aod process. Other articles where vacuum oxygen decarburization is discussed. Argonoxygen decarburization aod engineering dictionary. After initial melting the metal is then transferred to an aod vessel where it will be subjected to three steps of refining. Argon oxygen decarburization aod treatment is the recognized standard for stainless steel refining worldwide. May 06, 2016 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. 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. Mathematical modeling of the argonoxygen decarburization refining. Simulation of oxygen penetration and decarburisation in eaf using supersonic injection system francesco memoli, carlo mapelli, 1 pietro ravanelli 2 and marco corbella. Preventing decarburization in steel requires metallurgists and their customers to pay attention to the details. Astm e1077 14 standard test methods for estimating the. Modeling of the vacuum oxygen decarburization refining.
A comparison study on depth of decarburization and the role. Learn more about praxairs argon oxygen decarburization process that is used to make over 75% of the worlds stainless steel. Translation find a translation for argon oxygen decarburization in other languages. Argon oxygen decarburization, frequently referred to as aod, is an advanced technology for the refinement of iron, nickel, and cobalt based alloys. Aug 29, 2017 one such risk is decarburization, which can weaken steel parts and put them at greater risk of failure during their service. Kinetics of decarburization reaction in oxygen steelmaking process neslihan dogan, geoffrey a. Simulation of oxygen penetration and decarburisation in eaf. Decarburization occurs when metals are subjected to high temperatures, and the carbon present on the surface reacts with oxygen or hydrogen and diffuses. Practical model to simulate and to operate vacuum oxygen decarburization vod plant for stainless steelmaking conference paper pdf available may 2012 with 1,077 reads how we measure reads. 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. Argon oxygen decarburization furnace steel slag aod youtube. Aod provides an economical way to produce stainless steel with a.
More accurately, the chemical potential of carbon in the atmosphere may be lower than that in the steel being heat treated. In an aod, metal is subjected to three steps of refining. This process takes place when carbon existing in metals reacts with gases containing hydrogen or oxygen during heating at 700c. For high carbon melts at low partial pressures of oxygen, the decarburization rate was found to be independent of gas flow rate and was a linear function of oxygen partial pressure. Measuring and preventing decarburization in steel paulo. Carbon will therefore be removed from the steel by the process commonly known as decarburization. In a controlled trial, 7 samples were decarburized and results measured for both low oxygen level atmospheres and air table 1. Modeling of gas flows in steelmaking decarburization processes. May 06, 2016 argon oxygen decarburization furnace steel slag aod mineralproducts1.
Vacuum oxygen decarburization metallurgy britannica. A parabolic relationship was assumed between the decarburization rate and the carbon content c. Decarburization occurs when the metal is heated to temperatures of 700 c or above when carbon in the metal reacts with gases containing oxygen or hydrogen. Pdf practical model to simulate and to operate vacuum.
Carbon from the interior diffuses towards the surface, moving from high to low concentration and continues until the maximum depth of decarburization is established. Modeling of the vacuum oxygen decarburization refining process article pdf available in metallurgical and materials transactions b 311. Modeling of the vacuum oxygen decarburization refining process. Our facility our products major production facilities. Pdf simulation of fluid flow and oscillation of the argon oxygen.
In the production of stainless steel and other highalloy grades that contain highly oxidizable elements such as chromium, lowering the levels of carbon by regular oxygen injection has the undesirable consequence of oxidizing the alloying elements as well. Pdf modeling of the vacuum oxygen decarburization refining. Argon oxygen decarburization aod is a unique refinement process for iron, nickel, and cobalt alloys whereby huge quality and efficiency gains can be made. More specifically, two delaval nozzles from a vod vaccum oxygen decarburization process, which is used for producing stainless steels with ultralow carbon grades, was investigated for different vessel pressures. Astm e107714, standard test methods for estimating the depth of decarburization of steel specimens, astm international, west conshohocken, pa, 2014. Exclude inputs or outputs that can be documented to contribute less than 1 percent of the total mass of carbon into or out of the process.
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