Argon Oxygen Decarburization (AOD) Treatment is the recognized standard for stainless steel refining worldwide. Whether you are producing castings, wrought . Argon-oxygen decarburization: stainless steel: In the argon-oxygen decarburization process, a mixture of oxygen and argon gas is injected into the liquid steel. Argon Oxygen Decarburization, frequently referred to as “AOD”, is an advanced technology for the refinement of iron, nickel, and cobalt based alloys. By.
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AOD is widely used for the production of stainless steels and specialty alloys such as silicon steels, tool steels, nickel-base alloys and cobalt-base alloys.
Argon oxygen decarburization
During the final stage of blowing, the ratio of oxygen to argon is changed to 1: The installation of a lance and introduction of oxygen in the early stages of decarburization can reduce the time for a argoon.
Designed by Elegant Themes Powered by WordPress. The next step is the reduction step, in which the reduction additions are charged and stirred with an inert gas for a desired time.
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Another modification of the AOD process involves applying vacuum on the converter to reduce the consumption of argon and silicon as well as the process time when making low carbon grades.
AOD converter is a pear shaped vessel usually lined with basic refractory lining. The amount of stirring energy from the gas blown through the subsurface tuyeres and the formation of the carbon monoxide deep within the metal bath results in the converter processes being among the most intensely stirred metallurgical reactors.
It is part of a duplex process in which scrap or virgin raw materials are first melted in an electric arc furnace EAF or induction furnace.
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. This is due to the very low oxygen potential of the gas mixture, which minimizes chromium oxidation. Send a question or comment.
Ideally at this stage of the process, the chemistry of the liquid steel should meet the final specifications so that the heat can be tapped. The key feature in the AOD converter is that oxygen for decarburization is mixed with inert gas such as argon or nitrogen decarburizwtion injected through submerged tuyeres. The ratios can be done in any number of phases to facilitate the reaction. Such an approach is usually practiced by steelmakers to reduce argon usage and costs and still achieve a desired nitrogen specification.
Careful manipulation of slag, as it precipitates in the reaction, is decarburizatoin. It is part of a duplex process in which scrap or virgin raw materials are first melted in an oxygfn arc furnace EAF or induction furnace IF. Usually, the converter is turned down to a horizontal position and a sample of the liquid steel is taken for analyses at a carbon level of about 0.
Retrieved from ” https: Chromium pickup from the brick is possible. Sidewall mounted tuyeres are submerged while processing. After the ladle treatment, the steel is ready to be cast. If necessary, additional raw materials may be charged for small chemistry adjustments before tapping. The formation of a high basicity slag and the reduction of oxygen potential in the metal bath are good conditions for sulfur removal.
Side wall injection usually imparts maximum stirring energy to the bath for greatest efficiency of mixing. History of ferrous metallurgy List of steel producers.
The ratio is lowered with the progress of the decarburization. Desulphurization is achieved by having a high lime concentration in the slag and a low oxygen activity in the metal bath. Oxidation of carbon continues, but oxidation of chromium is limited.
The tapped bath is then either sent to a stir station for further chemistry trimming or to a caster for casting. Modern instrumentation has been developed arbon can take melt samples as well as steel temperatures using a specially designed sub lance with the converter in the upright position.
Other trimming alloy additions might be added at the end of the step. Sulfur removal is a slag — metal reaction that occurs during the reduction phase of the decarburiization. This argon dilution minimizes unwanted oxidation of precious elements contained in specialty steels, such as chromium. There are usually two to four tuyeres in the bottom.
Oxyygen a certain carbon level is achieved, the nitrogen gas is replaced by argon.
Argon oxygen decarburization – Wikipedia
After the change from nitrogen to argon, nitrogen is removed from the bath both by evolved carbon monoxide and argon. Converters that tap into a ladle car usually have a BOF type concentric cone top section.
This article needs additional citations for verification. The choice of refractory is dependent on the vessel operation pattern, final product specifications, and economics. Typical argoh volumes of Fecarburization converters are in the range 0. At this point, the process gases can be shut off and a small cooling flow protects the tuyeres.
Additions of lime are made to dilute the sulphur in the liquid steel bath. Refractory costs are a significant fraction of total operating costs.