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) converter is popularly used in the stainless steel making process. AOD has a top lance for oxygen injection and several.
|Published (Last):||19 October 2016|
|PDF File Size:||14.63 Mb|
|ePub File Size:||8.67 Mb|
|Price:||Free* [*Free Regsitration Required]|
Pattern welding Damascus steel Crucible steel Tatara furnace Cementation process. The decarburization step is controlled by ratios of oxygen to decarbutization or nitrogen to remove the carbon from the metal bath.
Other benefits include pinpoint accuracy in chemistry control down to 0. Decarburization time ranges from 20 to 35 minutes in modern fecarburization start from 1.
Decarburization occurs when dissolved carbon reduces the chromium and iron oxides that form. So, additions of lime are added to dilute sulfur in the metal bath. Since the blowing is done along with argon it is possible to carry out the decarburization at a lower temperature. These additions also serve to reduce the bath temperature as carbon and chromium oxygrn are exothermic. After 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 processs started with the blowing of inert gas argon, nitrogen and oxygen mixture.
Also, aluminum or silicon may be added to remove oxygen. Electro-slag remelting Vacuum arc remelting Argon oxygen decarburization. Cooling gases blown through the outer annulus shroud form a metal or oxide accretion called a mushroom at the tuyere tip. Annealing Low hydrogen Short circuit. A major modification of the AOD process involves the use of top blowing lance in addition to the side blowing tuyeres.
Argon-oxygen decarburization | metallurgy |
Please help improve this article by adding citations to reliable sources. Nitrogen control is a gas — metal reaction.
The effectiveness of reduction step is dependent on many factors including slag basicity and composition, temperature, mixing conditions in the converter and solid addition dissolution kinetics.
Low hydrogen Short circuit. 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.
American inventions Stainless steel Steelmaking. Refractory costs are a significant fraction of total operating costs.
Praxair can quote a server-only option for these systems. AOD provides an economical way to produce stainless steel with a minimal loss of precious elements.
Process gases are injected through submerged tuyeres that are installed in the side wall or bottom of the converter.
Argon oxygen decarburization AOD is a process primarily used in stainless steel making and other high grade alloys with oxidizable elements such as chromium ragon aluminum. Since the AOD vessel isn’t externally heated, the blowing stages are also used for temperature control.
The formation of high basic slag and the reduction of oxygen potential in the liquid steel bath are good conditions for sulphur removal. The AOD converter can be rotated downwards so that the side mounted tuyeres are above the bath level during charging of the liquid steel.
Desulphurization to very low levels is generally easier in dolomitic refractories because very basic slags can be used without detrimental effects on the bricks.
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 length of the blow period is determined by the starting carbon and silicon levels of the hot metal charged to the AOD converter. 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. Would like to more details of how to increase vessel life and to reduce refractory wear near tuyers.
The system accurately controls the flow rates and monitors the amount of gas injected into the bath to enable the operator to control the process and measure the total oxygen injected.
The major benefit associated with the dilution process comes into play when the oxygen to inert gas ratio is 1: