Three common stainless steel smelting process introduction

At present, there are three methods of stainless steel smelting in the world, that is, one-step method, two-step method, three-step method.

One-step method: electric furnace smelting stainless steel one step.Because the one-step method for raw materials demanding (return stainless steel scrap steel, low-carbon ferrochromium and Cr), in the production of high medium consumption of raw materials, energy, high cost, long smelting period, low productivity, less product variety, quality is poor, lining life is short, high consumption of refractory material, so it is rarely adopted stainless steel production.Three common stainless steel smelting process introduction (1)

Two-step process:Two-step method: 1965 VOD came into being, 1968 AOD refining device came into being, they played a decisive role in the change of stainless steel production process. The former is vacuum blowing oxygen decarburization, the latter is using argon and nitrogen to dilute the gas to decarburization. Combining either of these refining facilities with an electric furnace results in a two-step production process for stainless steel.
Three common stainless steel smelting process introduction (2)

The two – step steel-making process of electric furnace and AOD has the following advantages
1.AOD production process has low requirements on raw materials, and the carbon content of electric furnace steel can reach about 2%. Therefore, cheap high carbon FeCr and 20% stainless steel scrap can be used as raw materials to reduce the operating cost.
2.AOD method can remove the carbon in molten steel to 0.08% in one step. If the smelting time is extended and the content of Ar is increased, the carbon in molten steel can be further removed to less than 0.03%, except for the ultra-low carbon.With the exception of ultra-low nitrogen stainless steels, 95% of the varieties can be produced.
3.AOD two-step stainless steel has shorter production cycle and better flexibility than VOD
4.The total investment of AOD production system equipment is more expensive than VOD, but less than the three-step method.
5.AOD produces stainless steel directly, with fewer personnel and equipment, so the overall cost is lower.
6.AOD can use primary steelmaking water with carbon content less than 1.5%, so it can use low cost and high carbon FeCr, FeNi40 and 35% carbon steel scrap for charging, and the raw material cost is lower than VOD.

The two – step steel-making process of electric furnace and AOD has the following disadvantages
1.Lining life is short
2.Reduced ferrosilicon consumes a lot
3.At present can not produce ultra-low carbon, ultra-low nitrogen, stainless steel, steel contains high air content.
4.Argon gas consumption is high

At present, 88% of the world’s stainless steel is produced by two-step process, of which 76% is produced by AOD furnace.Therefore, AOD is more suitable for the use of large professional stainless steel factories.

Three-step method: electric furnace + compound blowing converter +VOD three-step smelting stainless steel.Its characteristic is that the electric furnace, as the melting equipment, is only responsible for providing semi-finished molten steel containing Cr and Ni to the converter, and the main task of the double-blowing converter is to quickly decarbonize oxygen blowing, so as to achieve the goal of maximum recovery of Cr.VOD vacuum oxygen blowing is responsible for further decarburization, degassing and composition fine-tuning.The three-step method is more suitable for the areas where argon gas supply is relatively short, the professional factories which use hot iron with high carbon content as raw material and produce low carbon and low nitrogen stainless steel with large proportion are adopted.


Post time: Jan-12-2021