The smelting process for the production of stainless steel is mainly divided into one-step, two-step and three-step,
of which the two-step process of EAF+AOD (Electric Arc Furnace+Argon Oxygen Refining Furnace) accounts for
about 70%, and the three-step process accounts for about 20%. With the low phosphorus iron is widely used in
stainless steel production, the new one-step stainless steel smelting process is also adopted by more and more
stainless steel production enterprises.
The early one-step stainless steel smelting process refers to the completion of scrap melting, decarburization,
reduction and refining processes in an electric furnace, the charge is smelted into stainless steel in one step.
With the continuous development of the refining process outside the furnace and the wide application of AOD
furnace in the field of stainless steel production, this one-step smelting production process of stainless steel
smelting with electric furnace only is gradually eliminated due to the long smelting cycle, low operating rate and
high production cost.
At present, many stainless steel production enterprises use part of the low-phosphorus or dephosphorized iron
instead of scrap, the iron and alloy as raw materials into the AOD furnace for stainless steel smelting, thus forming
a new one-step smelting process. The new one-step smelting process compared with the early one-step process
in the production process eliminates the electric furnace as a smelting link, which can reduce the cost and improve
the purity of molten steel;
However, the new one-step process has certain requirements for raw material conditions and product programs:
first, the phosphorus content of iron in the AOD furnace is less than 0.03%, so the smelting process must increase
the iron dephosphorization process; second, it is not applicable to stainless steel varieties with complex composition
and high alloy content.
Two-step stainless steel representative process route for EAF → AOD, EAF → VOD (electric arc furnace → VOD
vacuum refining furnace).EAF → AOD process capacity currently accounts for about 70% of the world's stainless
steel production capacity, of which the EAF furnace is mainly used to melt scrap and alloy raw materials, the
production of stainless steel premelt, stainless steel premelt and then enter the AOD furnace smelting into qualified
stainless steel steel molten steel. Two-step stainless steel smelting process does not require high raw materials, the
production cycle is slightly shorter than the one-step process, good flexibility, can be produced in addition to ultra-low
carbon, nitrogen stainless steel, 95% of the stainless steel varieties. Two-step smelting process of argon and other
media consumption is significantly reduced, but compared to the one-step and three-step method of argon and other
media consumption is still slightly larger; then the AOD furnace decarburization to the end of the oxygen content in
the molten steel, to be added to the ferrosilicon to reduce the oxygen in the molten steel, and therefore the ferrosilicon
consumption is high; in addition, the stainless steel contains a higher amount of gas.
The basic process of the three-step method is as follows: Primary refining furnace→Reblow converter/AOD furnace
→Vacuum refining device. Stainless steel three-step method is based on the two-step method to increase the deep
decarburization of the link, the smelting process of the production of fast-paced, the quality of products is high,
the content of nitrogen, hydrogen, oxygen and inclusions is low. Three-step stainless steel process has more process
flows, investment and production costs are higher; the system will require much maintenances.
