ARGON OXYGEN DECARBURIZATION PDF
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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The decarburization step is controlled by ratios of oxygen to argon or nitrogen to remove the carbon from the metal bath. Refractory costs are a significant fraction of total operating costs. After the change from nitrogen to argon, nitrogen is removed from the bath both by evolved carbon monoxide and argon.
Sidewall mounted tuyeres are submerged while processing. For example, with starting sulphur of 0. High wear areas of the converter, usually the tuyere wall, slag decarburizatiln, and transfer pad are zoned thicker and with higher quality refractory than other parts xecarburization the converter.
While typical BOF refractory campaigns dearburization months or years long, stainless converter campaigns are several days or weeks long. 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. The installation of a lance and introduction of oxygen in the early stages of decarburization can reduce the time for a heat.
Depending on final nitrogen specification for the stainless steel grade, the inert gas during the initial stages of decarburization can be nitrogen.
Other benefits of AOD process include pinpoint accuracy in chemistry control down to 0. The end result is a cleaner metal coupled with increased productivity. After tapping, the ladle is often stirred for composition homogenization and temperature uniformity along with flotation of inclusions.
Metal Refining with Argon Oxygen Decarburization (AOD) Refining Systems – Inductotherm Corp.
The AOD converter can be rotated downwards so that the side mounted tuyeres are above the bath level during charging of the liquid steel. Since the blowing is done along with argon it is possible to carry out the decarburization at a lower temperature. Other trimming alloy additions might be added at the end of the step. Tuyere size and number depend on specific process parameters. During the oxygen blow, silicon is oxidized before carbon.
The slice portion allows the crane to come close to the converter mouth. After a certain carbon level is achieved, the nitrogen gas is replaced by argon.
Iron and steel production. Praxair can review your system and design an upgrade using:. 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.
These are i decarburization, ii reduction, and iii final chemistry and temperature trimming. Additional silicon addition is needed if requirement of silicon is there to meet the silicon specification of some of the stainless steels.
Electro-slag remelting Vacuum arc remelting Argon oygen decarburization. Side wall injection usually imparts maximum stirring energy to the bath for greatest efficiency of mixing. Designed by Elegant Themes Powered by WordPress.
Chromium pickup from the brick is possible.
The intimate gas — metal contact and excellent slag — metal mixing facilitate refining reactions. The desire to increase the productivity has led to continuous charging of raw materials during the blow period as well as reduction period.
Haynes International Case Study Video. 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 decarburization reactions are as follow.
Oxidation of carbon continues, but oxidation of chromium is limited. Typical internal volumes of AOD converters are in the range 0. After a desired carbon and temperature level have decarburizatjon reached the process moves to reduction.
The molten metal is then decarburized and refined in a special AOD vessel to less than 0. For more Praxair videos, please visit our YouTube channel. During the final stage of blowing, aryon ratio of oxygen to argon is changed to 1: The blow is continued to attain 0.
The stages of blowing remove carbon by the combination of oxygen and carbon forming CO gas. In other projects Wikimedia Commons.
Argon oxygen decarburization
Decarburization time ranges from 20 to 35 minutes in modern converters start from 1. Also, aluminum or silicon may be added to remove oxygen. This page was last edited on 4 Octoberxecarburization This accretion protects the tuyere and surrounding refractory.
The molten metal is then decarburized and refined in an AOD converter to less than 0. 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. Bessemer process Open hearth furnace Electric arc furnace Basic oxygen process.