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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When the vessel is rotated, the tuyeres are above the bath. Views Read Edit View history. Other benefits of AOD process include pinpoint accuracy in chemistry control down to 0.
In the early days of the AOD process, the converter was tilted for raw material additions as well as for taking decarbirization and for measurement of temperature using immersion thermocouples.
The top lance can also be designed for blowing mixed gases such as inert gas — oxygen mixtures. Articles needing additional references from November All articles needing additional references. To drive the reaction to the forming of CO, the partial pressure of CO is lowered using argon or nitrogen. Praxair can review your system and design an upgrade using:. The ratio is lowered with the progress of the decarburization. Would like to more details of how to increase vessel life and to reduce refractory wear near tuyers.
Bottom injection usually improves wear characteristics in the barrel section of the converter. Other trimming alloy additions might be added at the end of the step. Decarburization occurs when dissolved carbon reduces the chromium and iron oxides that form.
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. The process is very popular because it combines higher metallic yields with lower material costs.
Magnesite chromite bricks are simultaneously acidic and basic and strict slag compositions must be maintained to prevent rapid wear. Additions of lime are made to dilute the sulphur in the liquid steel bath.
Decabrurization a question or comment. This is done in a ladle equipped with stirring facilities with or without the use of a ladle furnace. The transfer of decarburizatiom to slag takes place as per the following reaction. In zrgon initial stage, oxygen to argon in the ratio ranging from 5: 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.
Lime and dolomitic lime are sometimes added before the end of the blow to cool the bath and to reduce the volume of reduction additions.
Please help improve this article by adding citations to reliable sources. Pattern welding Damascus steel Crucible steel Tatara furnace Cementation process. The major benefit associated with the dilution process comes into play when the oxygen to inert gas oxygeen is 1: After a desired carbon and temperature level have been reached the process moves to reduction. The blow is continued to attain 0.
These additions also serve to reduce the bath temperature as carbon and chromium oxidations are exothermic.
Argon Oxygen Decarburization Process |
Bloomery produces sponge iron Blast furnace produces pig iron Cold blast Hot blast Anthracite iron Direct reduced iron. The key oxyge 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 molten metal is then decarburized and refined in an AOD converter to less than 0. Additional silicon addition is needed if requirement of silicon is there to meet the silicon specification of some of the stainless steels. Tuyere size and number depend on specific process parameters.
Oygen the transfer of liquid steel containing iron, chromium, carbon and nickel from EAF or IF to the AOD converter, high carbon ferro chrome is added and the blow is started with the blowing of inert gas argon, nitrogen and oxygen mixture. The decarburization step is controlled by ratios of oxygen to argon or nitrogen to remove the carbon from the metal bath. The gas control system supplies the process gases at nominal rates of 1. During the oxygen blow, silicon is oxidized before carbon.
High temperatures at the tuyere tip and high bath agitation place great demands on the converters refractory. Reduction recovers the oxidized elements such as chromium from the slag. It provides an economical way to produce stainless steel with a minimum loss of precious elements. Also, aluminum or silicon may be added to remove oxygen. Bottom blown converters have a variety of tuyere configurations depending on flow rates required. Decagburization at this stage of the process, the chemistry of the liquid steel should meet the final specifications so that the heat can be tapped.
Volatile elements with high vapour pressures, such as lead, zinc, and bismuth, are removed during the decarburization period.
Argon oxygen decarburization
Praxair can review your system and design an upgrade using: Sidewall mounted tuyeres are submerged while processing.
Any chromium oxide not reduced by carbon ends up in the slag, which can form a complex spinel. Magnesite chromite refractories have high decarrburization resistance but have a higher unit cost than dolomitic refractories. Desulphurization is achieved by having a high decarburisation concentration in the slag and a low oxygen activity in the metal bath.
While typical BOF refractory campaigns are months or years long, stainless converter campaigns are several days or weeks long. Retrieved from ” https: