ARGON-OXYGEN DECARBURIZATION PDF

Learn more about Praxair’s Argon Oxygen Decarburization process that is used to make over 75% of the world’s stainless steel. Argon Oxygen Decarburization (AOD) Treatment is the recognized standard for stainless steel refining worldwide. Whether you are producing castings, wrought . 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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The burning of carbon increases the bath temperature. Iron and steel production. This argon dilution of oxygen minimizes unwanted oxidation of precious elements contained in specialty steels, such as chromium.

The end result is a cleaner metal coupled with increased productivity. Send a question or comment. High wear areas of the converter, usually the tuyere wall, slag line, and transfer pad are zoned thicker and with higher quality refractory than other parts of the converter.

Phosphorus, which requires oxidizing conditions, cannot be removed in the converter processing. Your email address will not be published. Desulphurization to very low levels is generally easier in dolomitic refractories because very basic slags can be used without detrimental effects on the bricks.

Bottom injection usually improves wear characteristics in the barrel section of the converter. 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.

These tuyeres typically consist of a copper tube with a stainless steel outer tube. Views Read Edit View history.

Also, aluminum or silicon may be added to remove oxygen. Careful manipulation of slag, as it precipitates in the reaction, is important. By using this site, you agree to the Terms decarburzation Use and Privacy Policy. The molten metal is then decarburized and refined in an AOD converter to less than 0.

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Argon oxygen decarburization

In general, the bath temperature is controlled to less than deg C. Special designs exist for normalizing the flow in the annular gap. This accretion protects the tuyere and surrounding refractory. The process is very popular because it combines higher metallic yields with lower material costs. Dolomitic refractories are usually less costly than magnesite chromite refractories and chromium pickup is not a factor.

After initial melting the metal is then transferred to an AOD vessel decarburizarion it will be subjected to three steps of refining; decarburizationreductionand desulphurization. The key feature in the AOD converter is that oxygen for decarburization is mixed with inert gas such as argon or nitrogen and injected through submerged tuyeres. The system will be tailored to match your current operation with added features found only on the new systems.

American inventions Stainless decarburizatino Steelmaking. History of ferrous metallurgy List of steel producers.

During the oxygen blow, silicon is oxidized before carbon. Since the AOD vessel isn’t externally heated, the blowing stages are also used for temperature control. In the early days of the AOD process, the converter was tilted for raw material additions as well as for taking samples and for measurement of temperature using immersion thermocouples.

The AOD converter can be rotated downwards so that the side mounted tuyeres are above the bath level during charging of the liquid steel. The liquid steel, which contains most of the chromium and nickel needed to meet the final heat composition, is tapped at a temperature of to deg C from the EAF or the IF into a transfer ladle.

The ratio is lowered with the progress of the decarburization. Cooling gases blown through the outer annulus shroud form a metal or oxide accretion called a mushroom at the tuyere tip. Want to modernize and upgrade the functionality of your old AOD system cost-effectively?

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These additions also serve to reduce the bath temperature as carbon and chromium oxidations are exothermic.

The choice of refractory is dependent on the vessel operation pattern, final product specifications, and economics. Oxidation of carbon continues, but oxidation of chromium is limited. These are achieved by having a high lime concentration in the slag and a low oxygen activity in the metal bath.

Argon oxygen decarburization – Wikipedia

Argon oxygen decarburization for metal production Share Print. Electro-slag remelting Vacuum arc remelting Argon oxygen decarburization. Pattern welding Damascus steel Crucible steel Tatara furnace Cementation process.

A major modification of the AOD process involves the use of top blowing lance in addition to decatburization side blowing tuyeres.

Argon-oxygen decarburization | metallurgy |

This article needs additional citations for verification. AOD converter is a pear shaped vessel usually lined with basic refractory lining. Would like to more details of how to increase vessel life and to reduce refractory wear near tuyers. It is part of a duplex process in which scrap or virgin raw materials are first melted in an electric decarburzation furnace EAF or decarburisation furnace IF.

The reduction mix also includes lime CaO and fluorspar CaF 2. Any chromium oxide not reduced by carbon ends up in the slag, which can form a complex spinel. Nitrogen control is a gas — metal reaction.

Depending on final nitrogen specification for the stainless steel grade, the inert gas during the initial stages of decarburization can be nitrogen. Please help improve this article by adding citations to reliable sources.

Bottom blown converters have a variety of tuyere configurations depending on flow rates required.