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 decarburization step is controlled by ratios of oxygen to argon or nitrogen to remove the carbon from the metal bath. The length of the blow period is determined by the starting carbon and silicon levels decarburizatoin the hot metal charged to the AOD argon-oxyge.
Please help improve this article by adding citations to reliable sources. Additional silicon addition is needed if requirement of silicon is there to meet the silicon specification of some of the stainless steels. Other benefits of AOD process include pinpoint accuracy in chemistry control down to 0.
Argon oxygen decarburization for metal production
The AOD converter has tuyeres mounted in the sidewall or in the bottom. AOD process uses dilution technique for the decarburization of steel bath. American inventions Stainless steel Steelmaking. Sidewall mounted tuyeres are submerged while processing.
Argon-oxygen decarburization | metallurgy |
Praxair can review your system and design an upgrade using: Tuyere size and number depend on specific process parameters. Electro-slag remelting Vacuum arc remelting Argon oxygen decarburization. Want to modernize and upgrade the functionality of your old Argkn-oxygen system cost-effectively?
Also, aluminum or silicon may be added to remove oxygen. The important feature of an AOD converter is that it is normally side blown. Praxair can quote a decarburizatoon option for these systems. To achieve this, alloy additions are made with elements that have a higher affinity for decarburizatikn than chromium, using either a silicon alloy or aluminum.
The molten metal is then decarburized and refined in a special AOD vessel to less than 0. It provides an economical way to produce stainless steel with a minimum loss of precious elements.
Converters are typically zoned by thickness and brick quality to maximize lining life and minimize costs. Magnesite chromite refractories have high wear resistance but have a higher unit cost than dolomitic refractories. Special designs exist for normalizing the flow in the annular gap. From Wikipedia, the free encyclopedia. The installation of a lance and introduction of oxygen in the early stages of decarburization can reduce the time for a heat. After a certain carbon level is achieved, the nitrogen gas is replaced by argon.
For example, with starting sulphur of 0. As molten stainless steels do not generate foam, and most stainless steel refining processes are side or bottom-blown, the dimensions of a stainless refining converter are smaller than a comparable BOF basic oxygen furnace converter. 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. Your email address will not be published.
Unsourced material may be challenged and removed. Send a question or comment. Careful manipulation of slag, as it precipitates in the reaction, is important. After the ladle treatment, the steel is ready to be cast.
If the grade to be produced requires an extra low sulphur level, the bath is deslagged after the reduction step and another basic slag is added. Bottom blown converters have a variety of tuyere configurations depending on flow rates required.
Reduction recovers the oxidized elements such as chromium from the slag. This argon dilution of oxygen minimizes unwanted oxidation of precious elements contained in specialty steels, such as chromium.
AOD process refining has three major steps.
The process is argon-oxygsn popular because it combines higher metallic yields with lower material costs. The reduction mix also includes lime CaO and fluorspar CaF 2. These tuyeres typically consist of a copper tube with a stainless steel outer tube. Views Read Edit View history. Such an approach is usually practiced by steelmakers to reduce argon usage and costs and still achieve a desired nitrogen specification.
The number and relative positioning of tuyeres is determined in part by converter size, range of heat sizes, process gas flow rates and types of alloys refined. After the change from nitrogen to argon, nitrogen is removed from the bath both by evolved carbon monoxide and argon.
This page was last edited on 4 Octoberat This is due to the very low oxygen potential of the gas mixture, which minimizes chromium oxidation. Dcearburization choice of refractory is dependent on the drcarburization operation pattern, final product specifications, and economics.
This argon dilution minimizes unwanted oxidation of precious elements contained in specialty steels, such as chromium. Sulfur removal is a slag — metal reaction that occurs during the reduction phase of the process. The slice portion allows the crane to come argon-oxyhen to the converter mouth. Also, aluminum or silicon may be added to remove oxygen.
Other benefits include pinpoint accuracy in chemistry control down to 0. A major modification of the AOD process involves the use of top blowing lance in addition to the side blowing tuyeres.