AOD（Argon Oxygen Decarburization）process is a widely used steel de-carburizing technology with advanced productivity and efficient decarbonization capability,which has been widely used in metallurgical plants.
AOD process refers to the process in which stainless steel is subjected to oxygen-enriched argon (or air)-based furnace atmosphere carburizing.In this process,the carbon content in steel is reduced to very low levels by using the chemical reaction caused by adding oxygen to the carbon in steel,and the reduced carbon is oxidized and removed from the steel surface.The core elements of AOD de-carburizing process mainly include furnace atmosphere treatment,charging,heating,holding,cooling and unloading.
First of all,during the pre-treatment of AOD furnace atmosphere,argon gas containing oxygen is injected into the furnace. The oxygen is heated by the heat of steel melt and diffuses through the furnace atmosphere.Argon is mostly used because its low oxygen dissociation reduces the speed of chemical reaction, resulting in more uniform decarbonization of the steel melt.
After the carbon pre-treatment,the steel melt is charged into the AOD furnace to begin the next step of the process,heating. Heating should take place in a uniform and stable way.During heating,typical heating rate is about 300~400℃/h.The heating rate will affect the decarbonization rate and efficiency of the de-carburizing process.
After heating,the steel meltʹs temperature will stay at the Deoxidation-Carburizing Holding（DCH） temperature and be held for a few minutes ,which will promote the decarbonization of the steel melt and make it easier for the oxygen to react with decarbonized particles.
Then,the steel melt is cooled to the necessary temperature according to the requirements of the steel grade.The cooling rate should be controlled at 300~400℃/h and the cooling atmosphere should be free of oxygen and carbon,so as to ensure the stability of the decarburization results.
Finally,the steel melt is unloaded from the furnace and the final decarbonization results are judged.After passing the inspection and meeting the requirements,the steel melt can be processed further to make the finished product.
Advantages of AOD Decarburization
AOD decarburization technology has many advantages,such as good operability,less impurity,high decarbonization efficiency,energy saving and high productivity,etc.
Good operability refers to the fact that,the production parameters of AOD decarburization process are easy to adjust and control,which will make the decarbonization effect more stable and the production more steady.
The decarbonization of the AOD process uses oxygen-containing gases,which will produce fewer impuritiesduring de-carburizing,resulting in a cleaner surface of the steel after decarburizing.
The decarbonization speed of AOD process is very fast, and it can reach higher decarburization efficiency in a shorter time of stay in the furnace and shorter distance of furnace atmosphere treatment.
Compared with other de-carburizing processes, the power consumption of AOD process is much lower, and it is more energy-efficient,which can reduce the cost of production.
In addition,AOD process is one of the fastest processes among all decarbonization processes. It has higher production efficiency and can process more steel in the same amount of time.
Conclusion
AOD de-carburization process is a widely used technology in the steelmaking industry due to its advanced productivity and efficient decarbonization capability.It not only can reduce the carbon content in steel to very low levels, but also has the advantages of good operability,less impurity, high decarbonization speed,energy saving, high productivity and so on.Therefore,AOD decarburization process is an important process for metallurgical plants.
