JP2019065313A - Method for producing austenitic alloy material - Google Patents

Abstract

To provide a method for producing an austenitic alloy material having excellent corrosion resistance, in a severe environment including sulfuric acid, hydrochloric acid or the like, at low cost.SOLUTION: The present invention provides a method for producing an austenitic alloy material having a coating containing copper oxide, on at least part of the surface of a base material, wherein, the base material having a chemical composition containing, in mass%, C: 0.001-0.6%, Si: 0.01-5.0%, Mn: 0.1-10.0%, P: 0.08% or less, S: 0.05% or less, Cr: 15.0-55.0%, Ni: 40.0-70.0%, N: 0.001-0.25%, O: 0.02% or less, Mo: more than 0% to 20.0% or less, Cu: 0.5-7.5%, Co: 0-5.0%, W: 0-10.0%, Ta: 0-6.0%, Nb: 0-5.0%, Ti: 0-1.0%, B: 0-0.1%, Zr: 0-0.1%, Hf: 0-0.1%, Al: 0-1.0%, Mg: 0-0.1%, Ca: 0-0.1%, with the balance being Fe and impurities, is heated in a gas atmosphere containing a sulfur compound.SELECTED DRAWING: None

Description

  The present invention relates to a method of producing an austenitic alloy material.

  In order to realize the hydrogen society in the future, it is necessary to develop a process to produce hydrogen using clean energy that does not rely on fossil fuels, that is, without the generation of carbon dioxide. As a method of hydrogen production, IS process incorporating thermal decomposition of sulfuric acid and hydrogen iodide, high temperature water electrolysis (steam electrolysis), etc. are considered. The IS process is also called chemical hydrogen production, and is suitable for mass production of hydrogen. The principle is as follows and involves the decomposition of high temperature sulfuric acid and hydrogen iodide, and these reactions proceed with a catalyst such as platinum.

H ₂ SO ₄ → SO ₃ + H ₂ O (thermal decomposition of sulfuric acid: 300 300 ° C.)
SO ₃ → SO ₂ + 1 / 2O ₂ (decomposition of SO ₃ : 850850 ° C)
2HI → H ₂ + I ₂ (decomposition of hydrogen iodide: 400 ° C)
SO ₂ + I ₂ + 2H ₂ O → 2HI + H ₂ SO ₄ (Bunsen reaction: 200 ° C.)
H ₂ O → H ₂ + 1 / 2O ₂ (total reaction)

  The main challenges of this process include improving the corrosion resistance of materials used in the equipment / plant and improving the performance of the catalyst. Since a high temperature strong acid is used for the reaction, corrosion or deterioration of equipment and piping becomes serious. In particular, since the sulfuric acid decomposition part is exposed to a very strong corrosive environment, the corrosion is inevitable in the case of ordinary metal materials. In the process using a catalyst, the activity and durability of the catalyst itself are insufficient, and chemical engineering efforts are underway to improve the contact efficiency of the gas phase or the liquid phase together with the development of the catalyst material.

In Non-Patent Document 1, the corrosion resistance performance of corrosion resistant alloys such as Alloy 600 and Alloy 800 under sulfuric acid or SO ₃ at high temperature is investigated for the purpose of using plant materials for IS system.

  Further, Patent Document 1 discloses a stainless steel pipe having a coking resistance and a carburization resistance, which is provided with a Cr-deficient layer on the surface and a Cr-based oxide scale layer on the outside (surface side) thereof. Furthermore, in Non-Patent Document 1, application of ceramic or glass lining materials such as SiC is also examined. Almost no corrosion occurs with these materials, and the corrosion resistance is considered to be good.

JP 2005-48284 A

Nobuyuki Tanaka et al .: Materials and Environment, 55 (2006) pp. 320-324

  High alloy materials such as Alloy 600 or Alloy 800 have not obtained any corrosion resistance that can be used as an equipment material in an environment containing sulfuric acid. On the other hand, although alloy materials provided with an oxide film centering on chromium are expected to have corrosion resistance based on the barrier properties of the film, the corrosion resistance of the base metal itself is not sufficient in a high temperature sulfuric acid environment such as IS process. Although the ceramic or glass lining material has high corrosion resistance, the material cost is high, and corrosion is likely to occur at the connection because the connection is difficult. Furthermore, the ceramic is easily embrittled and may be damaged, which makes it difficult to use as a plant material.

  An object of the present invention is to provide a method for producing an austenitic alloy material excellent in corrosion resistance at low cost in a severe environment where it is exposed to high temperature steam or high temperature solution containing sulfuric acid or sulfur oxide containing sulfuric acid or hydrochloric acid. Do.

  The present invention has been made to solve the above-described problems, and the gist of the method for producing an austenitic alloy material described below.

(1) A method of producing an austenitic alloy material comprising a film containing a copper oxide on at least a part of the surface of a base material,
In mass%,
C: 0.001 to 0.6%,
Si: 0.01 to 5.0%,
Mn: 0.1 to 10.0%,
P: 0.08% or less,
S: 0.05% or less,
Cr: 15.0-55.0%,
Ni: 40.0 to 70.0%,
N: 0.001 to 0.25%,
O: 0.02% or less,
Mo: more than 0% but not more than 20.0%,
Cu: 0.5 to 7.5%,
Co: 0 to 5.0%,
W: 0 to 10.0%,
Ta: 0 to 6.0%,
Nb: 0 to 5.0%,
Ti: 0 to 1.0%,
B: 0 to 0.1%
Zr: 0 to 0.1%,
Hf: 0 to 0.1%
Al: 0 to 1.0%,
Mg: 0 to 0.1%,
Ca: 0 to 0.1%
Remainder: A base material having a chemical composition that is Fe and impurities,
Heating in a gas atmosphere containing a sulfur compound,
Method of manufacturing austenitic alloy material.

(2) The chemical composition of the base material is, by mass%,
Cu: 1.0 to 5.0%,
Contains
The manufacturing method of the austenitic alloy material as described in said (1).

(3) The film further contains Cr ₂ O ₃ ,
The manufacturing method of the austenitic alloy material as described in said (1) or (2).

(4) The copper oxide contains a composite oxide of Cu and Cr,
The manufacturing method of the austenitic alloy material in any one of said (1) to (3).

(5) The film further contains metal sulfide,
The manufacturing method of the austenitic alloy material in any one of said (1) to (4).

(6) The sulfur compound contained in the gas atmosphere is SO ₃
The manufacturing method of the austenitic alloy material in any one of said (1) to (5).

(7) The SO ₃ concentration in the gas atmosphere is 5 to 100% by volume,
The manufacturing method of the austenitic alloy material as described in said (6).

(8) The heating temperature in the gas atmosphere is 750 to 1000 ° C.
The manufacturing method of the austenitic alloy material in any one of said (1) to (7).

  According to the present invention, it is possible to manufacture an austenitic alloy material that exhibits excellent corrosion resistance in a high temperature severe environment containing sulfur oxides such as sulfuric acid or hydrogen halides.

The inventors of the present invention conducted intensive studies to obtain an alloy material exhibiting excellent corrosion resistance in an environment using high temperature strong acid such as IS process, specifically, an environment containing SO ₃ vapor over 800 ° C., The following findings were obtained.

The film formed on the surface of the alloy material exhibits catalytic activity for the decomposition of sulfur oxides, which is a step in the IS process. Here, the sulfur oxides, sulfuric acid _(H 2 _SO 4), sulfurous acid _{(H 2 SO 3), SO} 3, SO 2 , etc. _{SO x,} include such S 2 _{O 8.}

As the decomposition activity is higher, the corrosion resistance is improved, so it is considered that the corrosion resistance and the catalytic property are correlated. It is presumed that SO ₃ is decomposed by catalysis to become SO ₂ and the corrosiveness of the sulfur oxide is reduced.

  In particular, when copper oxide is contained in the film, these inherent catalytic actions are added to strengthen the catalytic action of the film, and as a result, the corrosion resistance is improved.

  Therefore, the present inventors further studied a method for producing an alloy material having a film containing copper oxide on the surface at low cost.

  In the case of forming a film containing a copper oxide on the surface of an alloy material, for example, a method is conceivable in which a solution containing copper nitrate is attached to the surface of the alloy material and heat treatment is performed in an appropriate atmosphere. However, in the manufacturing method involving the above-described steps, the alloy material can not be manufactured at low cost.

  In addition, when heat treatment is performed on a Cu-containing alloy material in a normal oxidizing environment, Cu is less likely to be oxidized because Cr contained in the alloy and having a lower oxidation potential than Cu is oxidized first. It is difficult to form a film containing copper oxide.

  On the other hand, when a Cu-containing alloy material is heated in a gas atmosphere containing a sulfur compound, a film containing copper sulfide is formed and then oxidized to form a film containing copper oxide.

  The present invention has been made based on the above findings. Hereinafter, each requirement of the present invention will be described in detail.

1. Chemical composition of base material The reasons for limitation of each element are as follows. In the following description, “%” of the content means “mass%”.

C: 0.001 to 0.6%
C is an element that combines with Cr and precipitates as Cr carbides at grain boundaries to increase the high temperature strength of the alloy. However, if it is contained excessively, the toughness deteriorates. In addition, a Cr-depleted layer may be formed at grain boundaries to impair intergranular corrosion resistance. Therefore, the C content is set to 0.001 to 0.6%. The C content is preferably 0.002% or more. The C content is preferably 0.45% or less, more preferably 0.3% or less.

Si: 0.01 to 5.0%
Since Si has a strong affinity to oxygen, it has an effect of uniformly forming a film mainly composed of Cr. However, if it is contained excessively, the weldability deteriorates and the structure becomes unstable. Therefore, the Si content is 0.01% to 5.0%. The Si content is preferably 0.03% or more. The Si content is preferably 3.0% or less, more preferably 2.0% or less.

Mn: 0.1 to 10.0%
Mn is an element having an effect of deoxidation and processability improvement. In addition, since Mn is an austenite-forming element, it is possible to replace a part of expensive Ni. However, when the chromium oxide film is formed by oxidation of the base material, if it is contained in excess, not only the formation thereof is inhibited but also the processability and weldability of the base material may be deteriorated. Therefore, the Mn content is 0.1% to 10.0%. The Mn content is preferably 5.0% or less, more preferably 2.0% or less.

P: 0.08% or less S: 0.05% or less P and S segregate at grain boundaries to deteriorate hot workability. Therefore, it is preferable to reduce as much as possible. However, since excessive reduction causes cost increase, it is acceptable if the P content is 0.08% or less and the S content is 0.05% or less. The P content is preferably 0.05% or less, more preferably 0.04% or less. The S content is preferably 0.03% or less, more preferably 0.015% or less.

Cr: 15.0-55.0%
Cr is an element mainly responsible for the corrosion resistance of the austenitic alloy. It generates Cr ₂ O _{3 due} to oxidation or corrosion of the base material and exhibits catalytic property and corrosion resistance. However, when incorporated in excess, it reduces the tube manufacturability and the tissue stability at high temperatures during use. Therefore, the Cr content is 15.0 to 55.0%. The Cr content is preferably 20.0% or more, more preferably 22.0% or more. Further, in order to prevent deterioration of the structure stability as well as the processability, the Cr content is preferably 35.0% or less, more preferably 33.0% or less.

Ni: 40.0 to 70.0%
Ni is an element necessary to obtain a stable austenitic structure according to the Cr content. In addition, when C intrudes into the steel, it has a function to reduce the infiltration rate. However, excessive incorporation not only leads to high cost but also leads to deterioration of manufacturability. Therefore, the Ni content is set to 40.0 to 70.0%. The Ni content is preferably 60.0% or less.

N: 0.001 to 0.25%
N is an element effective for high temperature strength improvement. However, when it is contained in excess, the processability is greatly inhibited. Therefore, the N content is set to 0.001 to 0.25%. The N content is preferably 0.002% or more, and more preferably 0.20% or less.

O: 0.02% or less O (oxygen) is an element present as an impurity. When the O content exceeds 0.02%, a large amount of oxide inclusions exist in the steel, which not only reduces the workability but also causes the surface damage of the steel pipe. Therefore, the O content is 0.02% or less.

Mo: More than 0% and 20.0% or less Mo is an element effective for improving high-temperature strength as a solid solution strengthening element, and is an element for improving corrosion resistance in a super strong acid environment including sulfuric acid or hydrochloric acid. In particular, it is considered that sulfur forms a MoS film to enhance corrosion resistance. However, when it is contained in excess, the precipitation of the sigma phase is promoted, resulting in deterioration of weldability and processability. Therefore, the Mo content is more than 0% and 20.0% or less. The Mo content is preferably 0.01% or more, more preferably 0.5% or more, and still more preferably 3.0% or more. The Mo content is preferably 15.0% or less, more preferably 10.0% or less.

Cu: 0.5 to 7.5%
Cu is an element which stabilizes the austenite phase and is effective in improving the high temperature strength, and also improves the corrosion resistance in a super strong acid environment containing sulfuric acid or hydrochloric acid like Mo. Moreover, in order to form the film | membrane which contains a copper oxide on the base material surface by heat processing, it is an essential element. However, when it is contained excessively, the hot workability is significantly reduced. Therefore, the Cu content is 0.5 to 7.5%. The Cu content is preferably 1.0% or more, more preferably 2.0% or more. The Cu content is preferably 6.5% or less, more preferably 5.0% or less.

Co: 0 to 5.0%
Co can replace part of Ni in order to stabilize the austenite phase. Therefore, Co may be contained as needed. However, when it is contained excessively, the hot workability is significantly reduced. Therefore, the Co content is 5.0% or less. The Co content is preferably 3.0% or less. In order to obtain the above effects, the Co content is preferably 0.01% or more.

W: 0 to 10.0%
Ta: 0 to 6.0%
Since both W and Ta are elements effective for improving the high temperature strength as a solid solution strengthening element, they may be contained as necessary. However, when it is contained in excess, it not only degrades the processability but also inhibits the tissue stability. Therefore, the W content is 10.0% or less, and the Ta content is 6.0% or less. The W content is preferably 8.0% or less. The Ta content is preferably 2.5% or less, more preferably 2.0% or less. In order to obtain the above effects, the content of at least one of W and Ta is preferably 0.01% or more.

Nb: 0 to 5.0%
Ti: 0 to 1.0%
Nb and Ti may be contained as necessary because they are elements which greatly contribute to the improvement of high temperature strength, ductility and toughness even if they are added in a very small amount. However, when it is contained excessively, the processability and weldability are degraded. Therefore, the Nb content is 5.0% or less, and the Ti content is 1.0% or less. In order to obtain the above effects, the content of at least one of Nb and Ti is preferably 0.01% or more.

B: 0 to 0.1%
Zr: 0 to 0.1%
Hf: 0 to 0.1%
B, Zr and Hf are all elements effective for strengthening grain boundaries and improving hot workability and high-temperature strength properties, and may be contained as necessary. However, if it is contained excessively, weldability is degraded. Therefore, the contents of B, Zr and Hf are all 0.1% or less. In order to obtain the above effect, the content of one or more selected from B, Zr and Hf is preferably 0.001% or more.

Al: 0 to 1.0%
Mg: 0 to 0.1%
Ca: 0 to 0.1%
Al, Mg and Ca are all elements effective to improve the hot workability, and may be contained as necessary. However, if it is contained excessively, weldability is degraded. Therefore, the Al content is 1.0% or less, and the Mg and Ca contents are all 0.1% or less. The Al content is preferably 0.6% or less, and the Mg and Ca contents are all preferably 0.06% or less. In order to obtain the above effects, it is preferable to contain one or more selected from Al: 0.01% or more, Mg: 0.0005% or more, and Ca: 0.0005% or more. Further, the content of Mg and Ca is more preferably 0.001% or more.

  In the chemical composition of the base material of the austenitic alloy material and the austenitic alloy pipe of the present invention, the balance is Fe and impurities.

  Here, “impurity” is a component mixed in due to various factors such as ore, scrap, etc. and various factors in the manufacturing process when the alloy is industrially manufactured, and it is acceptable within a range not adversely affecting the present invention Means one.

2. Heating Conditions The method for producing an alloy material according to the present invention is to heat the base material having the above-mentioned chemical composition in a gas atmosphere containing a sulfur compound.

  As described above, when an alloy material containing Cu is heated in a gas atmosphere containing a sulfur compound, copper sulfide is formed, and then part or all of it becomes a copper oxide.

The sulfur compound contained in the gas atmosphere is preferably SO ₃ . SO ₃ is to exert particularly an effect of selectively sulfidizing Cu contained in the alloy.

The concentration of SO ₃ in the gas atmosphere is not particularly limited, but is preferably 5 to 100% by volume. Moreover, in order to promote sulfidation of Cu, the SO ₃ concentration is more preferably 17% or more, and further preferably 20% or more.

  The gas atmosphere may contain an inert gas such as nitrogen or argon or water vapor.

  Also, the heating temperature in the gas atmosphere is not particularly limited, but is preferably 750 to 1000 ° C. When the heating temperature is less than 750 ° C., the growth of the film is slow and it is difficult to form a stable film. On the other hand, if the heating temperature exceeds 1000 ° C., the strength of the alloy material may be reduced. The heating temperature is more preferably 850 ° C. or more, and more preferably 950 ° C. or less.

  Furthermore, the heating time is not particularly limited, but if it is too short, the formation of the film becomes insufficient, so it is preferable to set it for 2 hours or more.

3. Film The austenitic alloy material produced by the method according to the present invention comprises a film containing copper oxide on at least a part of the surface of the base material. The copper oxide is an oxide based on copper.

The film preferably further contains a chromium oxide such as chromia (Cr ₂ O ₃ ). Cr ₂ O ₃ also has the effect of improving the corrosion resistance of the alloy material and is decomposable as a catalyst to sulfur oxides.

Further, the type of copper oxide is not particularly limited as long as CuO, Cu ₂ O, etc. are contained. In addition to that, a complex oxide of Cu and Cr may be included as a copper oxide. Sulfides of Cu sulfided by the action of sulfur compounds, by reaction with chromium oxide present in the coating to form a CuCr 2 _{O 4,} CuCrO composite oxide such as _2.

  Also, some of the Cu sulfides may remain without being oxidized. Therefore, Cu sulfide may be contained in the film. In addition to Cu, metal sulfides such as Cr may be contained in the film.

  The thickness of the film is not particularly limited, but is preferably 0.1 to 50 μm. If the thickness is less than 0.1 μm, the barrier effect may be insufficient. On the other hand, when the thickness exceeds 50 μm, the amount of stress accumulated in the film increases, and cracking and peeling easily occur. As a result, the penetration of sulfur oxides and hydrogen halides becomes easy, which may lead to a reduction in corrosion resistance. The thickness of the film is preferably 0.5 μm or more, more preferably 1.0 μm or more. The thickness of the film is preferably 20 μm or less, more preferably 10 μm or less.

  The composition of the film can be measured by thin film X-ray diffraction (XRD). Also, the thickness of the film can be measured by X-ray photoelectron spectroscopy (XPS).

4. Catalyst performance (SO ₃ decomposition activity)
Since the austenitic alloy material produced by the method according to the present invention is provided with the above-mentioned film on at least a part of the surface of the base material, it has catalytic activity for the decomposition of sulfur oxide containing sulfuric acid. By having the decomposition action, the corrosion resistance of the base material is improved, and by using it as a piping material etc. in chemical processes involving decomposition of sulfur oxides such as IS process, it contributes to the improvement of decomposition efficiency as a process be able to.

The degree of SO ₃ decomposition activity of the austenitic alloy material according to the present invention is not particularly limited, but the SO ₃ supply rate per unit area: 0.0071 g / cm ² / min and the reaction temperature: 850 ° C. The decomposition rate of SO ₃ is preferably 8.0 × 10 ⁻⁵ g / cm ² / min or more. The decomposition rate of SO ₃ is more preferably 5.0 × 10 ⁻⁴ g / cm ² / min or more, further preferably 1.0 × 10 ⁻³ g / cm ² / min or more, 2 It is particularly preferable that it is not less than 0 × 10 ⁻³ g / cm ² / min. The decomposition rate of SO ₃ (g / cm ² / min) means the amount of SO ₃ decomposed (g / min) under the above conditions divided by the reaction area, ie the film area (cm ² ) that can be in contact with gas. Do.

The SO ₃ supply rate is calculated by SO ₃ concentration (g / L) × flow rate (L / min) / reaction area at normal temperature. The reaction area refers to the area covered by the film which can be in contact with the reaction gas. Above this supply rate of 0.0071 g / cm ² / min, the zero-order reaction, so-called reaction rate-limiting approaches. Therefore, when evaluating the decomposition rate of SO ₃ , a feed rate of 0.0071 g / cm ² / min or more may be employed.

Although the method of measurement of the decomposition rate of SO ₃ is not limited, it can be carried out as follows. The reaction gas is circulated at a constant rate through the tubular sample so that the inert gas such as nitrogen or argon containing a fixed concentration of SO ₃ gas does not release, the temperature is raised to 850 ° C., and the SO ₃ is decomposed The concentration of generated SO ₂ and / or O ₂ is quantified, multiplied by the gas flow rate to calculate the amount of decomposition (g / min) and divided by the reaction area. The concentration of SO ₃ is not limited, but is preferably set to about 2 to 20% by volume from the viewpoint of measurement accuracy and ease of handling. The flow rate may be appropriately set according to the SO ₃ concentration so that the SO ₃ supply rate is 0.0071 g / cm ² / min or more.

  EXAMPLES Hereinafter, the present invention will be more specifically described by way of examples, but the present invention is not limited to these examples.

  Various alloys having the chemical compositions shown in Table 1 were melted in a high frequency heating vacuum furnace, and hot forging, hot rolling and cold rolling were performed by a conventional method to produce an austenitic alloy material having a thickness of 2 mm. Subsequently, the solution treatment was performed for 30 minutes within the temperature range of 1100-1200 degreeC.

After that, from the above alloy materials, test No. Each time, three kinds of test specimens for film analysis, corrosion resistance test, and catalytic test were cut out. The test pieces for film analysis and corrosion resistance test have a width of 1 cm, a length of 3 cm, and a thickness of 2 mm, and have a surface area of 6 cm ² on the reverse side. In addition, the test pieces for the catalytic test are sized to have a surface area of 50 cm ^{2 on the} reverse side.

By heating each test piece under the conditions shown in Table 2, a film containing a copper oxide was formed on the surface of each test piece. Specifically, a test piece is placed in a flow test furnace (outside diameter 20 mm, inside diameter 16 mm) made of quartz, concentrated sulfuric acid is added to the gas while flowing argon, and SO ₃ gas is vaporized at 350 ° C. or higher. To adjust the gas flow rate, SO ₃ concentration and temperature.

  With respect to each of the test pieces obtained as described above, the analysis of the film, the corrosion resistance evaluation and the catalytic property evaluation were performed by the following method.

<Analysis of film>
For the test pieces for film analysis, the composition of the film was specified by XRD, and the thickness of the film was measured by XPS.

<Evaluation of corrosion resistance>
A specimen for corrosion resistance test was placed in a quartz tube, and heated to 850 ° C. while flowing argon gas. Next, concentrated sulfuric acid was pyrolyzed at 350 ° C. or higher to generate SO ₃ , and mixed with argon gas to flow 27% SO ₃ gas through the quartz tube. After 1000 hours, the corrosion loss was measured by the difference in weight before and after the test of the sample. Furthermore, the corrosion resistance of the alloy material was comprehensively evaluated in consideration of the change in the form of the film and the presence or absence of intergranular corrosion and oxidation of the base material under the film.

<Evaluation of catalytic property>
The test piece for the catalytic test was placed in the same quartz tube as above, and heated to 850 ° C. while flowing argon gas into the quartz tube. Next, SO ₃ obtained by thermal decomposition of concentrated sulfuric acid as described above was introduced and circulated in a quartz tube while being mixed with argon gas.

At this time, the amount of decomposition of concentrated sulfuric acid and the amount of argon gas were adjusted so that the reaction gas had a flow rate of 1000 mL / min and the SO ₃ concentration was 10% by volume. From the test conditions, the SO ₃ supply rate was 0.0071 g / cm ² / min. The reaction was evaluated by washing the product gas with an iodine solution and measuring the concentration of O ₂ which is one of the products with a gas chromatograph. Then, the decomposition rate (g / cm ² / min) of SO ₃ was calculated by dividing the SO ₃ decomposition amount (calculated from twice the amount of oxygen, g / min) per unit time by the area.

  These results are shown together in Table 2.

  As shown in Table 2, Test No. 2 satisfying all the requirements of the present invention. It can be seen that 1 to 9 show excellent corrosion resistance. And, when the film was observed, the film was sound and no peeling or cracking occurred. Furthermore, no signs of corrosion were observed in the base material.

  On the other hand, test No. 1 in which the film contains no copper oxide. In the case of No. 10, the corrosion resistance and the catalytic property were inferior.

  According to the present invention, it is possible to obtain an austenitic alloy material and an austenitic alloy tube exhibiting excellent corrosion resistance in a high temperature severe environment containing sulfur oxides such as sulfuric acid or hydrogen halide.

Claims (8)

A method of producing an austenitic alloy material comprising a film containing a copper oxide on at least a part of the surface of a base material,
In mass%,
C: 0.001 to 0.6%,
Si: 0.01 to 5.0%,
Mn: 0.1 to 10.0%,
P: 0.08% or less,
S: 0.05% or less,
Cr: 15.0-55.0%,
Ni: 40.0 to 70.0%,
N: 0.001 to 0.25%,
O: 0.02% or less,
Mo: more than 0% but not more than 20.0%,
Cu: 0.5 to 7.5%,
Co: 0 to 5.0%,
W: 0 to 10.0%,
Ta: 0 to 6.0%,
Nb: 0 to 5.0%,
Ti: 0 to 1.0%,
B: 0 to 0.1%
Zr: 0 to 0.1%,
Hf: 0 to 0.1%
Al: 0 to 1.0%,
Mg: 0 to 0.1%,
Ca: 0 to 0.1%
Remainder: A base material having a chemical composition that is Fe and impurities,
Heating in a gas atmosphere containing a sulfur compound,
Method of manufacturing austenitic alloy material. The chemical composition of the base material is in mass%,
Cu: 1.0 to 5.0%,
Contains
The manufacturing method of the austenitic alloy material of Claim 1. In the film, Cr ₂ O ₃ is further contained,
The manufacturing method of the austenitic alloy material of Claim 1 or Claim 2. The copper oxide includes a composite oxide of Cu and Cr,
The manufacturing method of the austenitic alloy material in any one of Claim 1- Claim 3. In the film, metal sulfide is further contained,
The manufacturing method of the austenitic alloy material in any one of Claim 1- Claim 4. The sulfur compound contained in the gas atmosphere is SO ₃
The manufacturing method of the austenitic alloy material in any one of Claim 1- Claim 5. The SO ₃ concentration in the gas atmosphere is 5 to 100% by volume,
The manufacturing method of the austenitic alloy material of Claim 6. The heating temperature in the gas atmosphere is 750 to 1000 ° C.,
The manufacturing method of the austenitic alloy material in any one of Claim 1-7.