JP2001164312A - Method for melting austenitic stainless steel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a melting method of an austenitic stainless steel, by which, even in the case of omitting the cleaning of a steel slab and a steel hoop from the view point of the productivity and the economy, the development of uneven luster on a steel plate surface is profitably avoided and the austenitic stainless steel plate product having good surface luster can be manufactured. SOLUTION: When the austenitic stainless steel is melted, the molten steel after completing the oxidizing refining, is deoxidized with Si and Ti without using Al, and the Si content and the Ti content in the molten steel are adjusted to <=0.40 mass % and not higher than prescribed upper limit values, respectively, and also, the oxygen activity in the molten steel at 1,570 deg.C is controlled to <=5 ppm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing austenitic stainless steel, and more particularly to a method for producing a uniform glossy surface in a steel sheet obtained by subjecting a continuously cast slab to hot rolling and cold rolling. The present invention relates to a technique for melting stainless steel, which is a raw material suitable for steel.

[0002]

2. Description of the Related Art Austenitic stainless steel, for example, SUS304, is the most excellent stainless steel in cold workability and weldability in addition to moderate corrosion resistance and heat resistance, and is the most versatile material. It is. Furthermore, it is the best material among metallic materials with respect to fracture toughness at cryogenic temperatures. Since this austenitic stainless steel sheet is often used for the outer plates of various devices, one of the required characteristics is that it has excellent surface gloss. Austenitic stainless steel is obtained by continuously casting molten steel produced by a converter, a vacuum degassing apparatus, or the like into a slab, for example, a slab. It is usually manufactured through the steps of pickling, maintenance of a steel strip by a grinder, cold rolling, finish baking, and finish pickling. At that time, from the viewpoint of economy, there are cases where the heating temperature in the heating furnace in the hot rolling step is lowered, the pickling rate of the hot-rolled sheet is increased, or the grinder care step of the slab and the steel strip is omitted. There are many.

[0003]

The steel sheet obtained through the above-described process is characterized in that portions having different glosses are continuously formed on the surface of the steel sheet in a band shape having a predetermined width. Frequently occur, and the appearance of the steel sheet as a product is impaired, which is a serious quality defect.

[0004] Therefore, the present invention can be applied to the case where the maintenance of the slab and the steel strip is omitted from the viewpoint of productivity and economy.
An object of the present invention is to propose a method for melting austenitic stainless steel, which advantageously prevents the occurrence of uneven surface gloss of a steel sheet and enables production of an austenitic stainless steel sheet product having good surface gloss.

In austenitic stainless steel, when continuously casting the material, a tundish immersion nozzle (hereinafter simply referred to as a nozzle) due to inclusions in molten steel.
Blockage easily occurs, which is a cause of hindering operation. These inclusions are generally used for raising the temperature of molten steel or molten iron, Al addition-Al ₂ O ₃ generated by oxygen blowing, and Al removal performed before Ti addition for improving and stabilizing the Ti yield. Al ₂ O ₃ produced by the acid, and then
This is a Ti-Al-O-based inclusion formed by adding Ti.

Techniques for avoiding the blockage of the nozzle include (a) controlling the adhesion of inclusions to the nozzle by adding Ca to the tundish (lowering the melting point of the inclusions), and (b) Ar gas from the nozzle. For example, control of the adhesion of inclusions to the nozzle by blowing such as (c) control of the adhesion of inclusions to the nozzle by changing the material or structure of the nozzle is known.

[0007] However, the method (a) uses Ca, which not only causes an increase in cost but also involves complicated operations. In the above method (b), the gas used in the casting of molten stainless steel is retained in the steel,
This may cause pinhole defects. The above-mentioned method (c) includes, for example, reducing the concentration of SiO ₂ in the nozzle material to reduce the starting point of inclusions on the nozzle, performing special inclusion prevention processing on the nozzle inner surface, or It is implemented by providing an adiabatic slit in
It was difficult to completely suppress nozzle blockage by these means.

Therefore, the present invention also proposes a method for advantageously avoiding nozzle blockage, which is a problem when continuously casting austenitic stainless steel.

[0009]

Means for Solving the Problems In order to investigate the cause of the above-mentioned uneven gloss, the inventors observed the surface of the steel sheet where the uneven gloss occurred. It was found that the appearance of the muscle part was different from that of the normal part.
In other words, the surface crystal grain size in the streak is smaller than that in the normal part, and the area ratio of grain boundary erosion that occurs during pickling is high. It was estimated that the glossiness was lower than that of the normal part, resulting in uneven gloss.

[0010] In order to clarify the reason for the difference in crystal grain size of the surface layer, a more detailed investigation was conducted.
It was found that fine precipitates on the order of several tens of nanometers existed in the surface layer of the steel sheet, which acted as pinning sites for crystal grain boundaries, and that the size and amount of the precipitates were different between the streak portion and the normal portion. That is, fine precipitates in the streaks having a small crystal grain size are:
The size was smaller and larger than the normal part. It is presumed that the difference in the distribution of fine precipitates acting as pinning sites at the crystal grain boundaries caused a difference in the crystal grain size. When the composition of this fine precipitate was identified, Cr and
It was a composite precipitate in which sulfide adhered to the Mn oxide.

Further, by paying attention to the fact that the fine precipitates are oxides, the relationship between the oxygen content in the molten steel and the uneven gloss of the product plate was investigated, and a clear correlation was found. here,
FIG. 1 shows the oxygen activity (a ₀ ) at 1570 ° C., which is the normal end temperature of refining of SUS 304 steel, which is a typical type of austenitic stainless steel, by the VOD method as an index of the oxygen content in the steel. The relationship with the evaluation of unevenness in gloss of the product steel sheet was shown.
The gloss unevenness was evaluated in three stages: A: no gloss unevenness, B: slight gloss unevenness was recognized but the shipment judgment was passed, and C: gloss unevenness occurred and the shipment judgment was rejected. As is evident from FIG. 1, it is necessary to set the oxygen activity at 1570 ° C. to 5 ppm or less in order to at least obtain the evaluation B for uneven glossiness.

The mechanism by which the unevenness in gloss is suppressed when the oxygen content in the steel decreases is not completely clear, but the size and amount of the fine precipitates are reduced by the decrease in the oxygen content as the source of the fine precipitates. It is presumed that this is due to the fact that the distribution difference hardly occurs.

As described above, in order to suppress the uneven gloss, it is only necessary to lower the oxygen content in the steel, and for that purpose, it is sufficient to enhance the deoxidation. Generally, to lower oxygen,
It is sufficient to increase the amount of deoxidizing elements such as Al, Si and Ti. However, an excessive increase of deoxidizing elements has the following side effects.

[0014] Al increases: by the formation of Al ₂ 0 _{3 inclusions,} cause immersion nozzle clogging during continuous _casting, trapped with inhibit operation, the slab surface portion Al ₂ O ₃ clusters in the continuous casting mold In this case _{, the} surface cleanliness is impaired, and _a steel sheet surface eaves is inevitably generated, which is not preferable as _a deoxidizing element.

Increase of Si: When the Si content is excessive, the descaling property at the time of pickling of a steel sheet is hindered, and a scale residual defect is induced on a product sheet.

Ti increase: When the Ti content is excessive, TiN is generated by the reaction with N in the steel, and when the TiN clusters are trapped in the surface layer of the slab in the continuous casting mold, the surface cleaning is impaired. However, the occurrence of eaves on the surface of the steel sheet is inevitable.

The present invention reduces the oxygen content in steel while avoiding the above-mentioned side effects when the deoxidizing element is increased.
The purpose of the present invention is to prevent the occurrence of uneven gloss on the surface of the steel sheet, and its gist configuration is as follows.

That is, according to the present invention, when smelting austenitic stainless steel, the molten steel after the oxidation refining is deoxidized with Si and Ti without using Al, and the Si in the molten steel is removed.
The austenitic stainless steel is characterized in that the content is adjusted to 0.40 mass% or less, the Ti content is adjusted to the upper limit value determined by the following formula, and the oxygen activity in the molten steel at 1570 ° C is controlled to 5 ppm or less. It is a manufacturing method. [Mass% Ti] max = 0.001 / [mass% N] where [mass% Ti] max: upper limit of Ti content in molten steel (mass%) [mass% N]: nitrogen content in molten steel ( mass%)

Further, the present invention provides a method for producing austenitic stainless steel in which molten steel after oxidation refining is used.
Deoxidize with Si and Ti without using Al, reduce the Si content in the molten steel to 0.40 mass% or less and the Ti content to the upper limit determined by the following formula, and calculate the temperature of 1570 ° C from the components in the molten steel A process for producing austenitic stainless steel, characterized in that the oxygen activity in the molten steel is 5 ppm or less. [Mass% Ti] max = 0.001 / [mass% N] where [mass% Ti] max: upper limit of Ti content in molten steel (mass%) [mass% N]: nitrogen content in molten steel ( mass%)

Here, in order to make the oxygen activity in the molten steel 5 ppm or less, it is advantageous to make the Ti content 0.005 mass% or more.

Furthermore, the present inventors have found that in order to suppress nozzle blockage during continuous casting, particularly nozzle blockage due to Al ₂ O ₃ inclusions, in addition to the above-mentioned Ti deoxidation, component adjustment of secondary refining slag And found that it is extremely effective to regulate the Al ₂ O ₃ concentration in the slag in relation to the basicity.

That is, the present invention is based on the above-described method for producing austenitic stainless steel, and further comprises the step of adding a component of the secondary refining slag after the decarburization treatment to (mass% CaO /
This is a method for melting austenitic stainless steel, which is adjusted to a range satisfying mass% SiO ₂ ) × (mass% Al ₂ O ₃ ) ≦ 15.

[0023]

Next, each manufacturing condition in the method of the present invention will be described. First, the oxidation refining in the present invention refers to the normal oxidation refining of austenitic stainless steel. That is, when austenitic stainless steel is manufactured by refining under atmospheric pressure in an AOD furnace or an electric furnace, oxygen gas, an oxygen-containing gas or an oxidizing substance is supplied to molten steel to mainly perform a decarburization reaction. This refers to the step of producing an oxidizing refining reaction. Also, VOD method,
When austenitic stainless steel is manufactured by refining under vacuum such as RH method or vacuum induction furnace, oxygen gas, oxygen-containing gas or oxidizing substance is supplied to molten steel under reduced pressure to perform decarburization reaction. The stage in which the oxidation refining reaction is caused, and the so-called vacuum decarburization refining period in which carbon in the molten steel is oxidized by the dissolved oxygen in the molten steel without supplying such an oxidizing source, are collectively referred to as oxidation refining.

The reason why Al is not used as a deoxidizing element is that, as described above, when Al is used, Al ₂ O ₃ inclusions are generated during deoxidation and nozzle clogging occurs during continuous casting, which hinders operation. In addition, if Al ₂ O ₃ clusters are trapped in the surface layer of the slab in the continuous casting mold, the surface cleanliness is impaired and the steel sheet surface eaves are forced to be generated, which is not preferable as a deoxidizing element. It is. Specifically, it is recommended that the Al concentration in the molten steel be limited to 0.0050 mass% or less, more preferably 0.0020 mass% or less.

Further, the Si content in molten steel at the time of Si deoxidation is set to 0.40 mass%.
The reason is that if the content of Si in the steel exceeds 0.40 mass%, a silica film is likely to be formed on the surface of the steel sheet. Because it triggers.

Further, the amount of Ti in molten steel at the time of Ti deoxidation (mass%)
Is set to 0.001 / [mass% N] or less for the following reason. Here, the inventors investigated in detail the relationship between the Ti content and the N content in the austenitic stainless steel and the surface eaves of the product steel sheet caused by the TiN cluster. As shown in FIG. 2, the occurrence of the surface eaves worsened with an increase in the amount of Ti and N in the steel.
It was found that the generation of the surface eaves was not suppressed unless the control was performed within the good region bordering the curve. This border is [mass
% Ti] × [mass% N] = 0.001. Therefore, the Ti content (mass%) in the molten steel is set to 0.001 / [mass% N] or less.

On the other hand, when performing Ti deoxidation, the Ti content in the molten steel is reduced to 0.00
The content of 5 mass% or more is advantageous for promoting deoxidation and reducing the oxygen concentration in the molten steel.

Further, the reason why the oxygen activity in the molten steel at 1570 ° C. after deoxidation was set to 5 ppm or less, as is apparent from FIG. 1570 ° C for unevenness evaluation B
It is necessary to make the oxygen activity at 5 ppm or less. Further, in order to obtain a gloss unevenness rating A without gloss unevenness, it is preferable that the oxygen activity at 1570 ° C. is 3 ppm or less.

As described above, it is possible to effectively prevent the unevenness of the gloss of the steel sheet surface by reducing the oxygen content in the steel without causing the nozzle clogging, the steel sheet surface eaves, and the scale residual defect, which are side effects when the deoxidizing element is increased. It is.

In particular, to avoid nozzle blockage, a decarburization process
The components of the secondary refining slag after the treatment are as follows: (mass% CaO
SiO_Two) × (mass% Al_TwoO_Three ) Adjust within the range that satisfies ≦ 15
Preferably. That is, Al in slag_TwoO_Three Containing
If the rate is high, Al in the slag_TwoO_Three Is reduced
Al in molten steel increases, and this Al re-oxidizes during casting,
_TwoO_Three It becomes a cluster and induces nozzle blockage.
You. The basicity of slag (mass% CaO / mass% SiO_Two)
Is high, the Al in the slag_TwoO_Three Reduction is likely to occur
You. Therefore, in this way Al in the slag_TwoO_Three Influences the reduction of
Two factors, namely, Al in secondary smelting slag._TwoO_Three Dark
To regulate the degree in relation to basicity, Al _TwoO_Three cluster
Work effectively to suppress nozzle generation and avoid nozzle blockage.
To use. Therefore, the inventors have proposed Al_TwoO_Three Generate cluster
Effects of the above two factors on
After examining various indices, the basicity of slag and Al_TwoO
_Three, Ie, (mass% CaO / mass% SiO_Two) × (mas
s% Al_TwoO_Three ) Can be better organized
It is.

Here, in the continuous casting of steel conforming to SUS304, as shown in FIG.
, The ratio B / A × 1 of the opening area B narrowed by the deposit 3 to the original opening area A of the discharge port 2
The nozzle opening ratio was determined for each casting heat by setting 00 (%) as the nozzle opening ratio. The results are shown in FIG. 4, where the components of the secondary smelting slag are (mass% CaO / mass% Si
When O ₂ ) × (mass% Al ₂ O ₃ )> 15, the nozzle opening ratio is reduced, that is, the nozzle blockage progresses, and it becomes impossible to use the nozzle due to the nozzle blockage when the casting heat number is about 4. On the other hand, the component of the secondary refining slag is (mass% CaO / mass
When (% SiO ₂ ) × (mass% Al ₂ O ₃ ) ≦ 15, even if the number of heats of casting is 10, multi-continuous casting is achieved with almost no nozzle blockage.

It has been described above that, based on experimental data, the occurrence of uneven brightness in a steel sheet obtained by hot rolling and cold rolling an austenitic stainless steel can be predicted by the oxygen activity at 1570 ° C. However, in actual refining, oxygen activity cannot always be measured when the temperature of molten steel is exactly 1570 ° C., depending on refining conditions and the like. In such a case, it is possible to estimate the oxygen activity under the condition of 1570 ° C. by thermodynamic calculation from the component values in the molten steel.

That is, according to the present invention, after oxidizing and refining austenitic stainless steel, Si and Si are used without using Al.
Since oxygen is deoxidized using Ti, the oxygen activity in the molten steel is defined by the deoxidation equilibrium equation for Si (Equation (1) below) or the deoxidation equilibrium equation for Ti (Equation (2) below) It is the lower value of the oxygen activity a ₀ . Therefore, the composition of the molten steel is analyzed, and the oxygen activity at the assumed temperature of 1570 ° C. can be estimated from the component values. The percentages shown below are all mas
s%. Serial ^{_{log (a Si · a o 2}} / a SiO2) = -30110 (T + 273) +11.4 ---- (1) log (a Ti · a o 2 / a Tio2) = -33660 / (T + 273) +11. 7 ---- (2) where a _x is the activity of each element or oxide, and a _Si = f _Si · [% Si] ---- (3) a _Ti = f _Ti · [ % Ti] ---- (4) However, f _x is the activity coefficient of each _{element, log f Si = 0.18 [%} C] +0.103 [% Si] -0.0146 [% Mn] +0.005 [% Ni] -0.0003 [% Cr] +0.058 [% Al] +0.586 [% Ti] ---- (5) log f Ti = 1.0 [% Si] - 0.043 [% Mn] -0.016 [% Cr] +0.042 [% Ti] - --- (6)

[0034] On the other hand, a _SiO2 and a _TiO2, first a _SiO2
Is known to be derived by the following equation. _{log a SiO2 = 0.036 (% MgO} ) +0.061 (% Al 2 O 3) +0.123 (% SiO 2) - 0.595 (% SiO 2) / (% CaO) - 6.456 ---- (7) Then, a _SiO2 by validation experiments in basic experiments and real machine by the present _{inventors, a TiO2 = 0.025 ---- (8} ) has been found to be suitable.

By using the above equations (1) to (8), the oxygen activity at the molten steel temperature of 1570 ° C. can be obtained. For example, when the chemical composition of molten steel is [% C] = 0.05, [% S]
i] = 0.40, [% Mn] = 1.0, [% Cr] = 18.2, and [% Ni] = 8.5, and the slag composition during deoxidation treatment is (% Ca).
(O) = 53, (% SiO ₂ ) = 35, (% MgO) = 7 and (% Al ₂ O ₃ ) = 10
In the case of the above, the oxygen activity a _{o at the} molten steel temperature of 1570 ° C
And the relationship between [% Si] and [% Ti] is calculated by the above equation (1).
Calculating using (8), the result shown in FIG. 5 is obtained.

[0036]

Example 1 Steel was removed from a 180-ton top-bottom blow converter and deoxidized in a VOD vacuum degassing apparatus. After decarburization, Si was removed without performing deoxidation with Al. The amount of Si in the molten steel is adjusted by adjusting the amount of Si in the molten steel to a predetermined amount and then performing Ti deoxidation to obtain [% S
i], [% Ti] and [% N] were changed, and a total of six levels of smelting were performed. The chemical components other than Si, Ti, and N are
C: 0.04 to 0.06%, Mn: 0.90 to 1.05%, Cr: 18.0 to 18.7
%, Ni: 8.0-8.5%, Al ≦ 0.001%, slag composition: CaO: 50-55%, SiO ₂ : 32-37%, MgO: 5-7
%, A1 ₂ 0 _3: was 6 to 10%.

Next, continuous casting was performed using a one-strand slab continuous casting rock. Slab thickness is 200mm, width is 1040 ~
It was 1280 mm. Then, without care of the obtained slab, after heating at a temperature of 1230 to 1260 ° C., hot rolling is performed to obtain a hot-rolled sheet having a thickness of 4 mm, and it is subjected to ingot-pickling, and a steel strip grinder is cleaned. After cold rolling to 1.0 mm without any finish, finish baking-finish pickling was performed. The surface of the final product steel sheet thus obtained was inspected and evaluated for uneven gloss, surface eaves and scale residue. The evaluation results are shown in Table 1 together with [% Si], [% Ti], [% N], the oxygen activity at 1570 ° C., and [% Ti] × [% N] in the molten steel.

[0038]

[Table 1]

As is clear from the results shown in Table 1,
Austenitic stainless steel sheets Nos. 1 to 3 manufactured using steel melted according to the conditions specified in the present invention.
Shows satisfactory results with respect to uneven gloss, surface eaves and scale residue, whereas 1570 ° C
Molten steel in an oxygen activity a _o is in the unsatisfactory performance of the steel sheet No. 4 in uneven gloss evaluation C does not satisfy the 5ppm or less in. On the other hand, the Ti content (mass%) in molten steel is 0.001 / N in molten steel.
In steel sheet No. 5 which did not satisfy the amount (mass%) or less, the generation of surface eaves exceeding the allowable range was observed. Also, the amount of Si in the molten steel
In steel sheet No. 6, which did not satisfy 0.40 mass% or less, generation of scale residue was observed.

Example 2 Steel was removed from a 180 t top-bottom blow converter and deoxidized by a VOD vacuum degassing apparatus. After decarburization, Si deoxidation was performed without performing Al deoxidation. Then, the amount of Si in the molten steel is adjusted to a predetermined amount, and then Ti deoxidation is performed to obtain [% S in the molten steel.
i], [% Ti] and [% N], and slag components after decarburization were variously changed, and a total of 10 levels of smelting were carried out.
The chemical components other than Si, Ti and N are as follows: C: 0.04 to 0.06
%, Mn: 0.85 to 1.10%, Cr: 17.8 to 18.5%, Ni: 7.9 to
8.5% and Al ≦ 0.001%.

Next, continuous casting was performed under the following conditions to produce a slab having a thickness of 200 mm and a width of 1040 to 1280 mm. Then, without care of the obtained slab, it is heated to a temperature of 1230 to 1260 ° C., then hot-rolled to form a hot-rolled sheet having a thickness of 4 mm, and is subjected to sintering-pickling and steel strip grinder care. Then, after cold rolling to 1.0 mm, finish baking-finish pickling was performed. The surface of the final product steel sheet thus obtained was inspected and evaluated for uneven gloss and surface eaves. The results of this evaluation were compared with [% Si], [% T
i], [% N], Al ₂ O ₃ amount in slag, slag basicity, 157
Together with the oxygen activity at 0 ° C and [% Ti] x [% N],
It is shown in Table 2.

[0042]

[Table 2]

As is clear from the results shown in Table 2,
Austenitic stainless steel sheets No. 11 to 15 manufactured using steel melted in accordance with the conditions specified in the present invention.
The nozzle clogging during its manufacture, with respect to gloss unevenness and surface eaves, whereas show the results of any sufficiently satisfactory, the steel sheet No. molten steel oxygen activity a _o at 1570 ° C. does not satisfy 5ppm or less 16 , 19 and 20: Uneven gloss evaluation C
Unsatisfactory results. On the other hand, the amount of Ti in molten steel (mass
%) Does not satisfy 0.001 / N or less in molten steel (mass%), steel sheet Nos. 18 and 20 showed surface eaves exceeding the allowable range. In addition, the slag condition during production is (% CaO /%
Steel plate obtained without satisfying (SiO ₂ ) × (% Al ₂ O ₃ ) ≦ 15
In Nos. 17, 19 and 20, nozzle clogging occurred during the production.

[0044]

As described above, by using the austenitic stainless steel melted according to the present invention, an austenitic stainless steel sheet having excellent surface gloss can be reduced in yield due to slab care and steel strip grinder care. Can be obtained without. Moreover,
Blockage of the nozzle when the production is performed by continuous casting can also be advantageously avoided. Therefore, it is possible to produce an austenitic stainless steel sheet having excellent surface properties without taking special facilities or means that cause an increase in cost, and an industrially extremely effective effect is brought about.

[Brief description of the drawings]

FIG. 1 is a graph showing the relationship between the oxygen activity at 1570 ° C. and the unevenness of gloss on the surface of a steel sheet.

FIG. 2 is a diagram showing the relationship between the amounts of Ti and N and the occurrence of surface flaws on a steel sheet.

FIG. 3 is a diagram for explaining a definition of a nozzle opening ratio.

FIG. 4 is a diagram showing a relationship between a nozzle opening ratio and a casting heat number.

FIG. 5 is a graph showing the relationship between the concentration of a deoxidizing element and the oxygen activity at 1570 ° C.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Seiji Nabeshima 1 Kawasaki-cho, Chuo-ku, Chiba City, Chiba Prefecture Inside the Technical Research Institute of Kawasaki Steel Co., Ltd. (72) Yasuo Kishimoto 1 Kawasaki-cho, Chuo-ku, Chiba City, Chiba Prefecture Kawasaki 4K013 AA01 BA08 CB09 CE00 DA08 DA12 EA03 EA04 EA05 FA01 FA05

Claims (4)

[Claims] 1. In producing an austenitic stainless steel, the molten steel after oxidizing and refining is deoxidized with Si and Ti without using Al, and the Si content in the molten steel is 0.40 mass% or less and Ti A method for producing austenitic stainless steel, characterized in that the content is adjusted to be not more than an upper limit determined by the following formula, and the oxygen activity in molten steel at 1570 ° C. is controlled to be 5 ppm or less. [Mass% Ti] max = 0.001 / [mass% N] where [mass% Ti] max: upper limit of Ti content in molten steel (mass%) [mass% N]: nitrogen content in molten steel ( mass%) 2. When smelting an austenitic stainless steel, the molten steel after the oxidation refining is deoxidized with Si and Ti without using Al, and the Si content in the molten steel is set to 0.40 mass% or less and Ti A process for producing austenitic stainless steel, characterized in that the content is not more than the upper limit determined by the following formula and the oxygen activity in the molten steel calculated from the components in the molten steel at a temperature of 1570 ° C is 5 ppm or less. . [Mass% Ti] max = 0.001 / [mass% N] where [mass% Ti] max: upper limit of Ti content in molten steel (mass%) [mass% N]: nitrogen content in molten steel ( mass%) 3. The method according to claim 1, wherein the Ti content is
A method for melting austenitic stainless steel, characterized in that the content is 0.005 mass% or more. 4. The method according to claim 1, wherein the component of the secondary refining slag after the decarburization treatment is (mass% CaO / mass%
A method for melting austenitic stainless steel, characterized in that it is adjusted to satisfy a range satisfying (SiO ₂ ) × (mass% Al ₂ O ₃ ) ≦ 15.