JPH04362114A - Method for adjusting aluminum of aluminum-containing stainless steel - Google Patents

Abstract

PURPOSE:To adjust the concn. of the aluminum component in an aluminum- contg. stainless steel to a target. CONSTITUTION:A molten steel 12 in which chromium is recovered from slag 13 by vacuum degassing is stored in a ladle 6. The insufficient component of the residual concn. A12 of the aluminum in the molten steel 12 from the target concn. A11 of the aluminum in the molten steel 12 is made up by charging an aluminum wire 27 into the molten steel 12 at a supply speed V. The aluminum yield is determined in correspondence to the supply speed V. The charging rate of the aluminum wire is determined with good accuracy by a value WA1 obtd. by determining the difference between A11 and A12 by the aluminum yield.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a method for producing aluminum-containing stainless steel in which, in a second smelting step, chromium oxide in the slag produced in the first smelting step is reduced and chromium is recovered into molten steel. In particular, the present invention relates to a method for adjusting aluminum in aluminum-containing stainless steel, which adjusts the aluminum component concentration in molten steel to a target level when adding aluminum after recovery.

0002

[Prior Art] In a stainless steel manufacturing method, particularly in a smelting process that has two steps, a first and a second, slag containing chromium oxide produced in the first smelting process is transferred to the second smelting process together with molten steel. A method of reducing chromium oxide in the slag and recovering chromium into molten steel, and an operating method therefor are disclosed in Japanese Patent Publication No. 17405/1983, Japanese Patent Publication No. 13406/1986, and Japanese Patent Application Laid-Open No. 1396/1983.
It is disclosed in No. 14.

For example, in Japanese Patent Publication No. 56-17405, in the so-called LD-VAC method, 27 to 30% chromium oxide (Cr2O3) is produced in the slag in the first smelting process, and in the first slag in the second smelting process, After vacuum degassing, which is a step, the amount of chromium oxide in the slag is reduced to about 2 to 3%, and an example is shown in which it is recovered in molten steel. Since the component concentration of chromium in stainless steel is relatively high and raw materials containing chromium are relatively expensive, improving the yield of chromium input greatly contributes to reducing the cost of stainless steel.

[0004] Chromium can be recovered from slag by adding silicon alloy iron (Fe-Si) to slag, as disclosed in Japanese Unexamined Patent Publication No. 1983-75646, filed by the same applicant. A common method is to reduce chromium oxide and recover chromium. However, according to the method of adding silicon, the amount of silicon in the molten steel also increases. When the amount of silicon increases, there is a problem that stainless steel becomes hard and workability deteriorates.

[0005] The method of reducing and recovering chromium oxide in slag into molten steel is also a method in which aluminum, which is stronger than silicon, is added as a reducing agent when producing aluminum-containing stainless steel. It has been adopted. Moreover, in this case, it is not just input for reduction recovery, but also material properties required for aluminum-containing stainless steel, improvement of welded parts during welding,
In order to improve the surface quality, it is necessary to add aluminum to the steel for various reasons explained below, and aluminum is also added for this purpose. Naturally, the amount of aluminum added to stainless steel greatly affects the material properties, etc., so it is necessary to control the aluminum content by adjusting it to a preset target level. .

[0006] In ferritic and martensitic stainless steels, by adding aluminum to the steel, the material properties become softer, and although the material strength slightly decreases, the ductility and bendability are improved. thing.

[0007] By adding and containing aluminum in the same type of steel, deep drawing workability etc. can be better improved, and the fatal and large amount of aluminum generated on the surface of steel products manufactured from the same type of steel can be improved. To improve surface quality by suppressing surface flaws (defects).

[0008] In similar steels, by adding aluminum to the steel, martensite (structure) that appears in the weld zone during welding can be suppressed, thereby improving the toughness of the weld zone.

■Related to item (■) above, if too much aluminum is added to steel, a large amount of aluminum oxide (or nitride) inclusions will be generated in the molten steel. Do not add too much as it will be trapped and become surface flaws (defects), leading to a decrease in surface quality and yield.

(2) Also in austenitic stainless steel, aluminum is added and contained in the steel for the same reason as in (2), (2) and (2).

[0011] Conventionally, aluminum-containing stainless steel has been manufactured based on the above-mentioned steel manufacturing method and other known conditions. The aluminum component concentration in molten steel is
This is corrected by adding aluminum as a fine adjustment material. The amount of aluminum input is determined by simple proportional calculations based on the compositional analysis of molten steel, while relying on the experience and intuition of the workers.

[0012] Even with the method of charging aluminum in the roughly determined amount, conventionally, for example, the following simplified method has been implemented, but it has various problems.

(1) The chromium oxide-containing slag generated in the first refining process is transferred to the second refining process together with the molten steel, and the molten steel is assembled with aluminum bars or aluminum blocks of a specific size and shape, for example, with reinforcing bars. An injection method in which the liquid is made into lumps and then poured into a lump to dissolve it.

[0014] This method requires manpower from preparation to operation, resulting in poor workability and is inefficient as it requires a long dissolution time due to the presence of lumps. In order to shorten this dissolution time, it is necessary to reduce the amount (input amount/time) and divide the solution into several batches, but this increases the number of batches and causes poor workability and is inefficient. Further, there is a problem in that a long melting time is required, and inclusions generated in the molten steel are likely to be trapped without being floated, leading to surface flaws.

(2) A method of mechanically introducing aluminum shot into molten steel similar to the above (1) using a charging device. The chromium oxide is deposited on the upper surface of the chromium oxide-containing slag layer that floats to the surface, and is not thrown into the steel and cannot be dissolved. In some cases, it may react violently with the slag, generating flames and damaging related equipment and equipment. has a certain problem.

[0016] Therefore, in place of such charging methods that have many problems, the so-called wire feeder method, in which wire-shaped aluminum is directly charged into molten steel, has come to be used for charging aluminum. ing. However, when feeding wire-shaped aluminum in this wire feeder method, the feed rate is calculated from the height of the steel bath in the ladle, the steel bath temperature, and the wire diameter, and the amount of feed is determined by using the operator's experience and intuition. I am trying to correct it.

[0017]

[Problem to be Solved by the Invention] However, in the aluminum adjustment method in the second smelting process using such correction, the adjustment amount depends on past performance data and the experience and intuition of the operator. There are problems as detailed below.

■The amount of chromium oxide transferred to the second smelting process is basically determined by the conditions of the first smelting process, based on the various main and auxiliary raw materials used and their composition, so the amount of chromium oxide transferred to the second smelting process is The amount of aluminum consumed for reducing and recovering the chromium oxide inside also varies. There is a limit to the amount of aluminum that can be added as a reducing agent to accurately match the fluctuations in the amount of chromium, and therefore, there will inevitably be excess or deficiency in the amount of aluminum added. Therefore, the aluminum component concentration in the steel at the final stage of reduction and recovery deviates from the target component concentration and does not reach the target concentration, resulting in large variations.

(2) When the amount of chromium in the chromium oxide-containing slag is large and the amount of aluminum consumed for recovery is greater than expected, aluminum for fine adjustment of the components is also consumed for chromium recovery. Therefore, the amount of aluminum added to adjust the aluminum component concentration to the target value inevitably increases. As the amount of expensive aluminum added increases, inclusions in the steel become more likely to be captured, leading to defects in the steel due to these inclusions, clogging of the tundish immersion nozzle in the subsequent casting process, and insufficient temperature control of the molten steel. Increases the manufacturing cost of stainless steel contained.

(2) When the actual amount of chromium in the chromium oxide-containing slag is small and the amount of aluminum consumed for recovery is less than expected, the concentration of aluminum components in the molten steel after chromium recovery increases. This necessitates wasteful oxygen blowing to adjust the aluminum component concentration by dealumination, which prolongs the working time, resulting in not only inefficiency but also an increase in manufacturing costs.

(2) Feeding aluminum in the form of a wire using the wire feeder method can improve the aluminum yield. However, when the amount of aluminum input is large, the time required to input the aluminum becomes longer, resulting in an extension of the time required to adjust the components. Furthermore, the second
When the stirring power of the container in the smelting process is large, air is drawn in when wire-shaped aluminum is introduced, leading to the pickup of nitrogen (N2) and the like. In addition, the time extension is
This causes a drop in molten steel temperature, making temperature control difficult.

[0022] The purpose of the present invention is to solve the above-mentioned problems,
The purpose of the present invention is to provide a method for adjusting the concentration of aluminum to a target level when adding aluminum to steel after chromium recovery, while naturally stabilizing chromium recovery operations in the production of aluminum-containing stainless steel.

[0023]

[Means for Solving the Problems] In the present invention, the most important method for achieving the above object is to clarify the influence of the aluminum input amount and the aluminum supply rate on the aluminum yield.

[0024] Therefore, as a result of statistical analysis of a large amount of actual operation data and various studies, the inventor of the present application found that in a container with a large stirring power, the aluminum yield is largely dependent on the aluminum supply rate; The present invention was completed based on the conclusion that it is appropriate to control the aluminum yield through adjustment.

That is, the present invention has a first smelting process of converter smelting, and a second smelting process in which vacuum degassing is performed as the first step and aluminum is charged as the second step. In a method for producing aluminum-containing stainless steel, in which chromium oxide in slag produced in a smelting process is reduced in a second smelting process and chromium is recovered into molten steel, in the second step, aluminum in the stainless steel is reduced. The value WAl is calculated by dividing the difference between the target concentration Al1 and the residual aluminum concentration Al2 in the steel after recovering chromium into the steel by the aluminum yield depending on the aluminum wire supply speed V.
This is an aluminum adjustment method for aluminum-containing stainless steel, which is characterized by supplying wire-shaped aluminum by (kg/Ton of molten steel).

Further, in the present invention, the division value WAl is determined by the temperature T1 at the end of the first step of the second step, the lower limit temperature T2 at the end of aluminum injection and component adjustment, and the temperature drop at the time of component adjustment other than aluminum. Using T3, the predetermined temperature drop coefficient k, and the aluminum wire supply speed V, the relational expression is

[0027]

[Equation 1] It is characterized in that it is determined by confirming that T1-T2-T3>k.WAl/V holds true.

Further, in the present invention, when the target aluminum concentration Al1 in the stainless steel is 0.01 to 1.5%, the aluminum yield depending on the aluminum wire supply speed V is calculated by the following equation:

[0029]

[Math 2] 2,25×10-4・V+8.16×10-3
It is characterized by the following.

[0030]

[Operation] In the method for adjusting aluminum in the second smelting step of aluminum-containing stainless steel according to the present invention, the target concentration Al1 of aluminum in stainless steel,
The required amount of aluminum is calculated from the difference between the chromium in the chromium oxide-containing slag transferred from the first smelting process and the aluminum residual concentration Al2 in the steel after recovering it into the steel, and it depends on the aluminum wire feeding speed V. By supplying wire-shaped aluminum by the value WAl (kg/Ton of molten steel) divided by the aluminum yield, the aluminum component concentration can be adjusted as desired.

Further, according to the present invention, the relational expression:

0032
]

[Equation 1] The left side of T1-T2-T3 > k・WAl/V indicates the temperature range within which temperature drop is allowed by adding aluminum, and the right side shows the temperature drop corresponding to the amount of aluminum added. Indicates. Since the aluminum supply amount WAl is determined after confirming that this relational expression holds true, it is possible to prevent the temperature of the molten steel from dropping to such a level that it becomes impossible to cast the molten steel after the second smelting step.

Further, according to the present invention, the aluminum yield depending on the aluminum wire supply speed V can be easily determined, and the value of the aluminum input amount WAl can also be easily determined by division.

[0034]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows a process equipped with a vacuum ladle degassing device, and FIG. 2 shows an aluminum charging process. This example is a so-called LD-VAC steel manufacturing method.

In the LD-VAC steelmaking method, oxygen blowing is performed in the converter, which is the first smelting step, to a predetermined carbon content. That is, carbon in the molten steel is oxidized and removed. At this time, chromium in the molten steel is also oxidized and transferred to the slag as chromium oxide. After decarburization, cold material for controlling the temperature of the molten steel and various materials for adjusting the composition are added, and then the molten steel is tapped into a ladle. At this time, the slag in the converter is also discharged into the ladle at the same time. The above is the first smelting process in the LD-VAC steelmaking method.

In the first step of the second smelting process, the molten steel ladle is set in the vacuum ladle degassing apparatus 1 shown in FIG. In the vacuum ladle degassing apparatus 1, the vacuum container 2 is composed of a movable vessel cover 3 and a vessel 4. The vessel 4 is provided below the floor 5 of the factory building. A ladle 6 that has received molten steel and slag from the converter in the first smelting process is housed in the vessel 4 . After storing the ladle 6, the vessel cover 3 is closed and the vacuum container 2 is closed.
The inside is sealed.

An inner lid 7 is provided at the top of the ladle 6, and oxygen gas 10 can be blown into the molten steel 12 from an immersion lance 9 inserted through an opening 8 of the inner lid 7. The immersion lance 9 is movable along a lifting direction 11. The ladle 6 contains molten steel 12 and a layered slag 13 covering the upper surface thereof. When the chromium oxide in this slag 13 is reduced,
Chromium moves into the molten steel 12 and is recovered as indicated by the arrow 14. The inner surface of the ladle 6 is coated with a refractory material. A porous plug 16 made of porous refractory material is provided on the bottom 15 of the ladle 6. When an inert gas such as argon (Ar) gas is blown through the porous plug 16, bubbles 17 are generated and the molten steel 12 is stirred. Argon gas is provided via argon line 18. Nitrogen (N2) gas or a blend thereof may be used as the inert gas.

The cross section of the ladle 6 is approximately circular, and a trunnion ring 19 is provided near the center. The trunnion ring 19 is angularly displaceable about the trunnion axis 20. The trunnion ring 19 is provided with an argon attachment/detachment portion 21 for supplying argon gas to the argon pipe line 18 . Argon gas is supplied through an argon supply pipe 22 as shown by arrow 23 . On the other hand, the gas existing in the vacuum container 2 is exhausted as shown by arrow 25 through an exhaust pipe 24 by another exhaust device (not shown). Inside the vessel 4, the ladle 6 is supported by a support 26.

When the inside of the vacuum vessel 2 is evacuated through the exhaust pipe 24 and a specified degree of vacuum is reached, the molten steel 12 is subjected to vacuum degassing treatment. Oxygen gas 1 via immersion lance 9 if necessary
0 blowing is performed to reduce the carbon concentration in the molten steel 12. In addition, ferroalloy and slag material are added (not shown), deoxidized, and chromium in the chromium oxide-containing slag 13 is recovered into the molten steel 12. The intensity of stirring caused by the oxygen gas 10 and bubbles 17 blown into the molten steel 12 is evaluated as stirring power.

In the production of aluminum-containing stainless steel, aluminum is used as a deoxidizing agent and a reducing agent in the above-mentioned refining process. After the vacuum degassing treatment, excess aluminum is detected as an aluminum residual concentration Al2 (%) in the molten steel 12 as a result of analysis. With respect to this aluminum residual concentration Al2, it is necessary to add just enough amount to meet the aluminum target concentration Al1 of the aluminum-containing stainless steel.

FIG. 2 shows the step of introducing aluminum by the so-called wire feeder method. In the second step of the second process of the LD-VAC smelting method, the aluminum wire 27 is charged into the molten steel 12 in the ladle 6 at high speed. The aluminum wire 27 is fed from a wire coil 28 and passed through a guide pipe 30 by a wire feeder 29.
The steel is fed into the molten steel 12 through the. Introducing aluminum by the wire feeder method allows aluminum to be directly introduced into the molten steel 12 without causing almost any reaction between the slag 13 and the aluminum wire 27, thereby improving the yield of the introduced aluminum. As for the method of introducing aluminum, for example, as introduced in the above (2) as the conventional method of introducing aluminum shot, a small cone-shaped aluminum shot with a diameter of about 20 to 30 mm is cast. The lumps are sprinkled onto the molten steel 12 from above the ladle 6 and charged. However, since this aluminum is lightweight and the layered slag 13 is relatively hard, there is a problem in that small lumps of the introduced aluminum shot sit on the top surface of the slag 13 layer and do not dissolve, making it difficult for reactions to occur. In addition, if the reaction time becomes longer, the temperature of the molten steel 12 may drop, aluminum, which is an active metal, may react with the molten steel and slag, and in combination with stirring with argon gas, air may be entrained in the molten steel. There is also a risk of occurrence of a pick-up phenomenon in which the nitrogen concentration increases.

However, according to the wire feeder method,
This aluminum injection can be performed satisfactorily. Figure 3
shows an example of actually measured data regarding the relationship between the aluminum yield (%) and the aluminum input speed V (m/min). This actual measurement data is 9mm in diameter and 99% in purity.
% aluminum wire is introduced into molten steel of steel type SUS430. The aluminum yield (%) shown in Figure 3
) is the amount expressed by the following number 3 expressed as a hundredth percentile.

[0043]

[Math 3]

In other words, it is the value obtained by dividing the amount of aluminum required to achieve the target concentration of aluminum in molten steel by the amount of aluminum wire input. The numerator of the equation (3) is equal to the amount of aluminum left in the molten steel after being added, and the denominator is equal to the amount of aluminum added to the ladle, so the aluminum yield can also be calculated using the equation (4) below. can be expressed.

[0045]

[Math 4]

When the relationship shown in FIG. 3 is expressed by the method of least squares, a relational expression between the aluminum yield (%) and the wire supply speed V (m/min) shown in Equation 5 below is obtained.

[0047]

[Math. 5] Aluminum yield (%) = 2.25×10-4・V
+8.16×10-3 In Figure 3, the amount of aluminum required to bring the aluminum in molten steel to the target concentration is the difference between the target concentration Al1 (%) and the residual aluminum concentration Al2 (%) in molten steel. It is. Therefore, the aluminum value W of the amount of wire to be input
Al corresponds to the input amount of Al wire as the denominator on the right side of Equation 3, and is given by Equation 6 below, which is a modification of Equation 3.

[0048]

[Math 6]

The value of WAl is calculated based on the unit weight of molten steel (1T
on), the weight of the aluminum wire to be introduced is determined according to the weight of molten steel after vacuum degassing treatment.

[0050] When aluminum or other additive elements are added to molten steel, the temperature of the molten steel is lowered. If the temperature of the molten steel drops too much, the next casting process will be hindered. On the other hand, due to constraints such as the lifespan of the refractories on the inner surface of the converter and the ladle 6, the temperature of the molten steel 12 at the start of the second step is limited to approximately 1700°C. Therefore, when introducing aluminum, it is necessary to confirm that the following relational expression 7 holds true.

[0051]

[Formula 7] T1-T2-T3>k・WAl/V where, T
1 is the temperature (°C) of the molten steel 12 at the end of the first step, T2 is the lower limit temperature (°C) of the molten steel 12 at the end of aluminum injection and composition adjustment in the second step, and T
3 is the temperature drop (°C) during adjustment of components other than aluminum. k on the right side of the inequality sign is a temperature drop coefficient k predetermined from experimental data, and a value of about 4 has been obtained. The value of this k is calculated from calcium (Ca
), the value is about 3. The relational expression of Equation 7 ensures that the temperature drop when aluminum is introduced does not adversely affect the next step, casting.

In this example, an LD-VAC process (equipment) with a nominal capacity of 70 tons was used, and steel type SUS4 was used.
30 aluminum-containing stainless steel is produced. According to FIG. 3, the higher the aluminum supply rate, the higher the aluminum yield. However, the wire feeder 29 shown in FIG.
The upper limit is about 300 m/min depending on the capacity of As the wire feeding speed increases, the position where the wire is melted goes deeper into the molten steel 12. However, if the depth of the molten steel 12 in the ladle 6 is exceeded, it may hit the bottom 15 of the ladle, damaging the refractory, or it may rebound and cause slag 13 on the surface of the molten steel.
The effect of this method disappears as the reaction occurs near .

In an example of the actual operation of this embodiment, a ladle 6 is set in the vacuum ladle degassing device 1 so that the total weight of molten steel + slag is 70.8 tons, and vacuum degassing treatment is performed. At the same time, 900 kg of aluminum as a deoxidizer and 600 kg of quicklime as a slag material were added. As a result, the aluminum residual concentration Al2 after the degassing treatment was 0.04%.

Therefore, by substituting this data and 0.12% of the target aluminum concentration Al1 of the product into each of the above calculation formulas, the results were as follows: V=225 m/min, WAl=
1.36 kg/ton of molten steel = 98 kg was obtained. As a result of feeding aluminum wire under these conditions, the aluminum component concentration in the aluminum-containing stainless steel product was 0.12%, and the aluminum feeding yield was 55.6.
%, and it was confirmed that the above-mentioned target aluminum concentration was achieved with high accuracy.

On the other hand, there is no need to pick up the nitrogen concentration level in molten steel, and there is no need to carry out aluminum adjustment such as dealumination.

The effects of this embodiment are shown in FIG. In the "non-recovery" method, in which chromium in the slag is not recovered, the time required for component adjustment is short, but the amount of chromium used is large and the cost of raw materials increases. In the conventional method of reducing and recovering chromium by introducing small chunks of aluminum shot, it takes a long time to adjust the components, and the manufacturing capacity of the equipment decreases. According to this embodiment, in which chromium is recovered by the wire feeder method, the time for component adjustment can be reduced, and together with the recovery of chromium, the manufacturing cost of aluminum-containing stainless steel can be reduced.

[0057] In the above embodiments, aluminum-containing stainless steel conforming to the SUS430 steel grade standard has been described, but it goes without saying that the present invention can be practiced with respect to other steel types. Table 1 shows examples of aluminum-containing stainless steels to which the present adjustment method can be applied. Regarding SUS430 and SUSXM15J1, although the Japanese Industrial Standards (JIS) G 4303 etc. do not specify aluminum components, the component ranges shown in parentheses are shown in parentheses in order to satisfy the required product characteristics as mentioned above. (%). Furthermore, in an actual product, the value of each component will be within a further restricted range as necessary.

[0058]

[Table 1]

[0059]

As described above, according to the present invention, in the second smelting step, chromium can be stably recovered from chromium oxide in slag in the production of aluminum-containing stainless steel by adding aluminum, The aluminum component concentration in the steel after chromium recovery is set to the target concentration Al1.
can be adjusted easily and quickly.

Furthermore, since the target aluminum concentration Al1 can be easily adjusted, variations in the amount of aluminum input for chromium recovery can be absorbed, and there is no need to input excess aluminum during the vacuum degassing process. This makes it possible to reduce the unit consumption of aluminum. In addition, since the amount of aluminum input during vacuum degassing treatment can be optimized, abnormal reactions between aluminum and oxides in the slag can be suppressed, and the vacuum caused by slag foaming due to air bubbles in the slag can be suppressed. It is possible to reduce the occurrence of equipment troubles in the ladle degassing device. Furthermore, the accuracy of the ingredients when adjusting the amount of aluminum is improved, the variation is reduced, there is no need to input surplus aluminum, no time is required for dealumination, and the second smelting process is The time required can be shortened.

[0061] Furthermore, since the aluminum wire is fed at a high feeding speed, the time for feeding the wire can be shortened, and pick-up of nitrogen etc. when feeding the wire can be prevented, improving the quality of aluminum-containing stainless steel. be able to.

[0062] As described above, the operability in the second smelting process of aluminum-containing stainless steel is improved, productivity is improved, and manufacturing costs can be significantly reduced.

Further, according to the present invention, the amount of aluminum to be introduced can be determined after confirming that the temperature of the molten steel is within a range that does not cause any trouble in the next casting process. This allows reliable operation.

Furthermore, according to the present invention, it is possible to accurately determine the aluminum yield with respect to the aluminum wire feeding rate based on experimental results. This makes it possible to improve the accuracy of reaching the target aluminum concentration Al1 in steel.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a schematic configuration of a vacuum ladle degassing apparatus 1 that performs the first step of a second smelting process.

FIG. 2 is a cross-sectional view schematically showing an apparatus for performing the second step of the second smelting process.

FIG. 3 is a diagram showing experimental data on the relationship between wire feeding speed and aluminum yield.

FIG. 4 is a time chart showing the effects of one embodiment of the present invention.

[Explanation of symbols]

1 Vacuum ladle degassing equipment 2 Vacuum container 3 Vessel cover 4 Vessel 5. Floor 6 Ladle 7 Inner lid 8 Opening 9 Immersion lance 10 Oxygen gas 12 Molten steel 13 Slag 15　Pot bottom 16 Porous plug 21　Argon attachment/detachment part 24 Exhaust pipe 27 Aluminum wire 28 Wire coil 29 Wire feeder 30 Guide pipe

Claims (3)

[Claims] 1. A first smelting process comprising a first smelting process of converter smelting, and a second smelting process in which vacuum degassing is performed as the first step and aluminum is introduced as a second step, and the first smelting process comprises: In the method for producing aluminum-containing stainless steel, in which chromium oxide in the slag generated in step 1 is reduced in a second smelting step and chromium is recovered in molten steel, in the second step, the target concentration Al1 of aluminum in the stainless steel is reduced. and,
The value WAl (kg/Ton) is calculated by dividing the difference between the aluminum residual concentration Al2 in the steel after chromium is recovered into the steel and the aluminum yield depending on the aluminum wire supply speed V.
An aluminum adjustment method for aluminum-containing stainless steel characterized by supplying only wire-shaped aluminum (molten steel). 2. The division value WAl is determined in advance by the temperature T1 at the end of the first step of the second step, the lower limit temperature T2 at the end of aluminum injection and component adjustment, and the temperature drop T3 at the time of component adjustment other than aluminum. Determined temperature drop coefficient k
and the aluminum wire supply speed V, the aluminum wire according to claim 1 is determined by confirming that the relational expression T1-T2-T3 > k・WAl/V holds true. Aluminum adjustment method for containing stainless steel. 3. When the target aluminum concentration Al1 in the stainless steel is 0.01 to 1.5%, the aluminum yield depending on the aluminum wire supply speed V is expressed by the following equation: 2,25 ×10-4・V+8.16×10-3
The method for adjusting aluminum in aluminum-containing stainless steel according to claim 1, wherein the aluminum content is determined by: