Fe-Cr-Al BASED ALLOY

Abstract

To provide an Fe-Cr-Al based alloy exhibiting superior cold workability and oxidation resistance without addition of a rare earth element.SOLUTION: An Fe-Cr-Al based alloy contains the following elements in mass%: Al: 2.0 to 6.0%, Cr: 9.0 to 23.0%, C: 0.010% or less, N: 0.010% or less, S: 0.0020% or less, Si: 0.010% or less, Mn: 0.10% or less, O: 0.010% or less, with the balance being Fe and unavoidable impurities excluding the above elements.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to an Fe-Cr-Al alloy excellent in cold rolling property and oxidation resistance, which is suitable for use as an oxidation-resistant member such as a combustor of various engines and turbines.

Background Art

[0002] In recent years, heat-resistant high-temperature parts such as various engines and turbines have been required to have a further higher use temperature in response to demands for reducing fuel consumption and carbon dioxide emissions. Among them, components that are particularly exposed to high temperatures during use include combustors, various high-temperature pipes, honeycomb-structured parts for catalyst support, etc. Since they have a sheet metal structure, thin metal materials are generally used. Thus, these heat-resistant high-temperature parts are in a severe environment where they are exposed to high temperatures during use in the form of thin metal materials. Therefore, as materials suitable for these parts, materials having characteristics of good oxidation resistance at high temperatures and good cold rolling property for being processed into thin sheets are required.

[0003] Conventionally, Fe-Cr-Al alloys have been attracting attention and used as heat-resistant steels having good oxidation resistance and cold rolling property. Also, several prior arts have been developed to further improve their oxidation resistance.

[0004] For example, Patent Document 1 (Japanese Patent No. 2579393) aims to propose an Fe-Cr-Al alloy strip excellent in oxidation resistance that can be stably manufactured without nozzle clogging by using a rapid cooling method. It is disclosed that the oxidation resistance of an Fe-Cr-Al alloy foil is improved by adding rare earth elements REM (Y, Ce, La, Pr, Nd) in an amount of 0.07 wt% or more (added in a larger amount than that of a normal rolled material).

[0005] Patent Document 2 (Japanese Patent No. 2587413) discloses that for the purpose of manufacturing an Fe-Cr-Al alloy foil that can be suitably used when the oxidation conditions in a catalytic converter are mild, based on Fe-Cr-Al which is a 3% Al alloy, by including Ti and La, an Fe-Cr-Al alloy excellent in oxidation resistance can be obtained.

[0006] Patent Document 3 (Japanese Patent No. 2991296) discloses that for the purpose of providing an Fe-Cr-Al alloy foil with extremely high oxidation resistance in a vibration environment where it is subjected to severe high-temperature repeated oxidation, by particularly excluding Ce actively and using it including La and Nd, the oxidation resistance of the Fe-Cr-Al alloy foil is improved.

[0007] Patent Document 4 (Japanese Patent No. 3283285) discloses that for the purpose of providing a ferrite stainless steel foil used for a high heat-resistant metal carrier that can withstand high-temperature engine exhaust (900 to 1000 °C), based on Fe-Cr-Al, by adding more than 0.01% of Ym, the oxidation resistance of the Fe-Cr-Al alloy foil is improved.

[0008] Patent Document 5 (Japanese Patent No. 3320831) discloses that for the purpose of providing an Fe-Cr-Al alloy excellent in strength and oxidation resistance at high temperatures, particularly an Fe-Cr-Al alloy plate with a thickness of 0.5 mm or less and a foil with a thickness of 0.1 mm or less, which are suitable as materials for catalyst carriers, by including C, Si, Mn, Cr, N, Ti, Zr, and a lanthanoid excluding La or Ce in the Fe-Cr-Al alloy, the high-temperature strength and oxidation resistance are improved.

[0009] Patent Document 6 (Japanese Patent Application Laid-Open No. 2002-105606) aims to provide an Fe-Cr-Al alloy that retains hot-rolled plate toughness and has excellent oxidation resistance even for extremely thin foils, as well as an extremely thin alloy foil and a catalyst support (metal support) and a catalyst device using the same. It does not contain elements such as Ti, Nb, V, Ta, and Ce that deteriorate oxidation resistance, adds Y as a rare earth element, and also adds Zr and / or Hf as C and N fixing elements for improving hot-rolled plate toughness. It is disclosed that the Y element itself has an effect of suppressing the decrease in hot-rolled plate toughness due to an increase in Al concentration.

[0010] However, any of the Fe-Cr-Al alloys described in the above documents have the essential constituent requirement of containing rare earth elements. Rare earth elements have the problems of extremely high costs, limited producing countries, few friendly countries, and uncertainty in stably obtaining them in the future.

Prior Art Documents

Patent Documents

[0011]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Patent Document 6

Summary of the Invention

Problems to be Solved by the Invention

[0012] The present invention has been made to solve the conventional problems described in the above background art section, and an object thereof is to provide an Fe-Cr-Al alloy excellent in cold rolling properties and oxidation resistance without adding rare earth elements.

Means for Solving the Problems

[0013] The inventors of the present invention focused on an Fe-Cr-Al alloy having a composition ratio different from that of the Fe-Cr-Al alloy containing rare earth elements as an essential component described in the above literature, particularly on suppressing the mixing of foreign substances and forming a dense and hard-to-peel Al2O3 film. As a result of intensive studies while constructing a hypothesis, surprisingly, even without containing rare earth elements, by setting Al and Cr in specific composition ranges respectively and reducing the concentrations of specific plural impurities to below a certain content ratio, it has been found that both excellent cold rolling properties and excellent oxidation resistance can be achieved, and the present invention has been completed as a means for solving the above problems.

[0014] That is, the gist of the present invention is as follows. [1] The content of each of the following elements is in mass%, Al: 2.0 to 6.0%, Cr: 9.0 to 23.0%, C: 0.010% or less, N: 0.010% or less, S: 0.0020% or less, Si: 0.010% or less, Mn: 0.10% or less, O: 0.010% or less, and the balance consists of Fe and inevitable impurities excluding the above elements, an Fe-Cr-Al alloy. [2] The content of each of the following elements is in mass%, Al: 2.0 to 6.0%, Cr: 9.0 to 23.0%, C: 0.010% or less, N: 0.010% or less, S: 0.0020% or less, Si: 0.010% or less, Mn: 0.10% or less, O: not more than 0.010%, and no rare earth element is added, and the balance consists of Fe and unavoidable impurities excluding the above elements, an Fe-Cr-Al alloy. [3] The Fe-Cr-Al alloy according to [1] or [2], which does not crack even when cold-rolled to a thickness of 0.4 mm without intermediate annealing when processed into a test piece with a thickness of 12×100×5 mm. [4] The Fe-Cr-Al alloy according to [1] or [2], when processed into a test piece with a thickness of 12×30×2 mm, has a weight gain of less than 5.0 mg / cm even when treated at 1300°C for 100 hours in the atmosphere. 2 [5] A thin plate member with a thickness of 50 μm to 2 mm, containing the Fe-Cr-Al alloy according to [1] or [2].

Advantages of the Invention

[0015] The Fe-Cr-Al alloy of the present invention is excellent in cold rolling property and also excellent in oxidation resistance, and can achieve both excellent effects simultaneously.

Brief Description of the Drawings

[0016]

Figure 1

Figure 2

Modes for Carrying Out the Invention

[0017] Hereinafter, an example of a preferred mode for carrying out the present invention will be described. However, the following embodiments are illustrative for explaining the present invention, and the present invention is not limited to the following embodiments at all.

[0018] [Components of the Fe-Cr-Al Alloy] The components of the Fe-Cr-Al alloy of the present invention will be described.

[0019] <al> The Fe-Cr-Al alloy of the present invention contains Al as an essential component. Al is a basic constituent element as an oxidation-resistant alloy. The mixing ratio of Al during alloy production is preferably 2.0% or more, more preferably 2.3% or more, and preferably 6.0% or less, more preferably 5.7% or less, by weight%. If it is below the above lower limit, the oxidation resistance may decrease, and if it exceeds the upper limit, the cold rollability may decrease.

[0020] <cr> The Fe-Cr-Al alloy of the present invention contains Cr as an essential component. Cr is a basic constituent element as an oxidation-resistant alloy. The mixing ratio of Cr during alloy production is preferably 9.0% or more, more preferably 9.5% or more, and preferably 23.0% or less, more preferably 22.5% or less, by weight%. If it is below the above lower limit, the oxidation resistance may decrease, and if it exceeds the upper limit, the cold rolling property may decrease.

[0021] <Impurity elements: C, N, S, Si, Mn, O> The Fe-Cr-Al alloy of the present invention may contain C, N, S, Si, Mn, and O as impurity elements, but each needs to be below a predetermined amount. By reducing the content in this way, it shows the effect of enhancing the cold rolling property and the oxidation resistance. The amounts of these impurity elements during alloy production are respectively C: 0.010% or less, N: 0.010% or less, S: 0.0020% or less, Si: 0.010% or less, Mn: 0.10% or less, O: 0.010% or less, It is necessary to be so. If it exceeds each upper limit for the above impurity elements, the effect of reducing the above impurity elements is impaired.

[0022] [Properties of Fe-Cr-Al alloy] The properties of the Fe-Cr-Al alloy of the present invention will be described.

[0023] <Cold rolling property> The Fe-Cr-Al alloy of the present invention does not crack even when a test piece with a thickness of 12×100×5 mm is cold-rolled to a thickness of 0.4 mm in the cold-rolling test described below. Therefore, the Fe-Cr-Al alloy of the present invention has excellent cold-rolling properties. In practice, annealing treatment is required to make it thinner, but in that case, the effects of the material and annealing on the cold-rolling properties cannot be distinguished. Therefore, in order to clarify the effect of the material, the cold-rolling properties without annealing are defined in this specification (such a mode may be referred to as "without intermediate annealing").

[0024] <Oxidation resistance> In the atmospheric oxidation test at 1300°C for 100 hours described below, the Fe-Cr-Al alloy of the present invention has an increase in oxidation weight of a test piece with a thickness of 12×30×2 mm, preferably 2 less than 5.0 mg / cm 2 and more preferably less than 4.8 mg / cm. Therefore, the Fe-Cr-Al alloy of the present invention has excellent oxidation resistance.

[0025] [Manufacturing method of Fe-Cr-Al alloy] The Fe-Cr-Al alloy of the present invention can be manufactured by using general methods such as melting, casting or forging, and rolling of high-purity Fe, Cr, and Al raw materials with a small amount of the impurity elements described above respectively. In addition, techniques related to known and well-known methods in the technical field may be appropriately combined for manufacturing. Also, along the procedures of the examples described below, ingot production by high-frequency melting using a calcia crucible, groove roll rolling using heating at 1100°C, and / or heat treatment at 1000°C for 1 hour may be sequentially performed. In order to homogenize Al, Cr, and Fe, which are essential elemental components of the present invention, the heat treatment temperature is preferably 920 to 1150 °C, more preferably 950 to 1100 °C, and most preferably 980 to 1050 °C. Also, the heat treatment time is preferably 0.5 to 3 hours, more preferably 0.75 to 2 hours, and most preferably 1 to 1.5 hours. The production conditions of the Fe-Cr-Al alloy of the present invention can be appropriately selected from the perspective of cost reduction for heat treatment as long as the alloy can exhibit the effects of the present invention.

[0026] [Function of the Fe-Cr-Al Alloy of the Present Invention] In the examples described below, various Fe-Cr-Al alloys of the present invention were actually produced, and a plurality of excellent effects of the alloy were demonstrated. Although all the detailed reasons are not necessarily strictly clear, they are presumed as follows. In the present invention, instead of adding rare earth elements to the Fe-Cr-Al alloy, high-purity raw materials are used to reduce the content of specific impurity elements in the alloy, that is, the contents of C, N, S, Si, Mn, and O. By reducing the content of specific impurity elements in the alloy, the mixing of foreign substances such as oxides, nitrides, and gas holes caused by the impurity elements in the alloy can be suppressed in the Al2O3 film of the oxide film formed when used at high temperatures. Due to this effect, the generation of cracks, gaps, etc. in the Al2O3 film can be suppressed, and as a result, a dense and difficult-to-peel Al2O3 film can be formed, and it is considered that the progress of oxidation of the entire material can be suppressed. The Fe-Cr-Al alloy having these characteristics has not been described or suggested in the aforementioned prior art documents, and has been found for the first time through the intensive studies of the present inventors.

Examples

[0027] Hereinafter, based on the examples, the production and characteristics of the Fe-Cr-Al alloy of the present invention will be described in more detail. Note that these descriptions are examples of the embodiments of the present invention, and the present invention is not limited to these examples.

[0028] [Step 1: Ingot production] Figure 1 is a photograph showing the appearance of the ingot produced in this example. As described later, in order to produce an ingot having the composition (component ratio) shown in Table 1 below, the raw material of the ingot was put into a calcia crucible and produced by high-frequency melting. As the raw material of the ingot, as Fe, ultra-high-purity granular electrolytic iron was used, as Al and Cr, ultra-high-purity granular raw materials were used, and as impurity elements, C, N, S, Si, Mn, and O were added as iron and master alloy, or elemental raw materials. Note that when ultra-high-purity Fe, Al, and Cr raw materials are used, since the above impurity elements are hardly contained in the alloy, they were intentionally added as appropriate. Specifically, as a method of intentionally adding the impurity elements C, N, S, Si, Mn, and O, C, Fe4N, FeS, Si, Mn, and FeO were used, respectively. The total weight of the raw material of the ingot was set to about 1.5 kg. The melting atmosphere was in argon gas, and an atmosphere in which it was evacuated and then partially replaced with argon was used. Casting was performed in a cast iron mold with an inner diameter of φ40 mm, cutting was performed at the position indicated by the dotted line in Figure 1, and the lower side (length about 90 mm) was used for the groove roll rolling described later.

[0029] [Step 2: Component analysis] In order to confirm the components of the ingot, elemental analysis was performed on Al and Cr, and specific impurity elements (C, N, S, Si, Mn, and O), and it was confirmed that the content of each element was the desired component content in weight %. The analysis results are shown in Table 1. An alloy within the range of the composition (component ratio) of the present invention was designated as an "invention alloy", and an alloy outside the range of the composition (component ratio) of the present invention was designated as a "comparative alloy" and indicated in the classification column.

[0030] [Step 3: Groove roll rolling] An ingot with a diameter of φ40mm and a length of 90mm obtained by cutting off the hot water was heated to 1100°C and subjected to grooved roll rolling. The shape of the groove was square, and the cross-sectional area was gradually reduced by passing the ingot through grooves with different sizes in sequence. Further, reheating was performed after approximately three rollings. The heating holding time was set to about 10 minutes. An example of the grooved roll rolling process is shown below using arrow symbols (the numbers are the side lengths (mm) of the groove): <Start> → Heating and holding → 38.2 → 35.0 → 31.7 → Reheating → 28.7 → 25.9 → 23.5 → Reheating → 21.3 → 19.3 → 17.5 → Reheating → 15.8 → 14.3 → 12.9 → <End> In this example, the grooved roll rolled material shown in Figure 2 was obtained by the above process.

[0031] [Procedure 4: Heat treatment] The grooved roll rolled material that did not crack or break during grooved roll rolling was heat-treated at 1000°C for 1 hour.

[0032] [Procedure 5: Property evaluation] From the grooved roll rolled material after heat treatment, the following two types of test pieces with different sizes were processed. · Test piece for cold rolling test: 12 × 100 × 5 mm thickness · Test piece for atmospheric oxidation test: 12 × 30 × 2 mm thickness Using the above test pieces, a cold rolling test and an atmospheric oxidation test in which the test pieces were held at 1300°C in the atmosphere for 100 hours were conducted. In the cold rolling test, the occurrence of cracks when rolling to a thickness of 0.4 mm without intermediate annealing was evaluated, and in the atmospheric oxidation test, the weight gain of the test pieces was evaluated. The measurement results are shown in Table 1 below.

Table 1

[0033] From Table 1, the following was found for the grooved roll rolled materials of each ingot produced with a specific composition (component ratio).

[0034] (1) Preferred component ratio of Al Alloys 1 to 5 are a group in which the Al component ratio is greatly varied. In this group, the component ratio excluding Al, Fe, and irreversible impurities other than the specific impurity elements, that is, Cr and specific impurity elements (C, N, S, Si, Mn, and O) is, in wt%, Cr (14.9 to 15.2%): C (0.004 to 0.007%): N (0.004 to 0.007%): S (0.0013 to 0.0017%): Si (0.004 to 0.007%): Mn (0.05 to 0.08%): O (0.004 to 0.007%). When Al is 2.3%, 4.1%, and 5.7% (alloys 2, 3, and 4 respectively), both the cold rolling property and oxidation resistance are good (◎). However, when Al is relatively small at 1.8% (alloy 1, comparative alloy), the oxidation resistance is poor (×), and when Al is relatively large at 6.2% (alloy 5, comparative alloy), the cold rolling property is poor (×).

[0035] (2) Preferred component ratio of Cr Alloys 6 to 10 are a group in which the Cr component ratio is greatly varied. In this group, the component ratio excluding Cr, Fe, and irreversible impurities other than the specific impurity elements, that is, Al and specific impurity elements (C, N, S, Si, Mn, and O) is, in wt%, Al (3.9 to 4.1%): C (0.004 to 0.007%): N (0.004 to 0.007%): S (0.0013 to 0.0017%): Si (0.004 to 0.006%): Mn (0.05 to 0.08%): O (0.004 to 0.007%). When Cr is 9.6%, 15.4%, and 22.3% (alloys 7, 8, and 9 respectively), both the cold rolling property and oxidation resistance are good (◎). However, when Cr is relatively small at 8.4% (alloy 6, comparative alloy), the oxidation resistance is poor (×), and when Cr is relatively large at 23.6% (alloy 10, comparative alloy), the cold rolling property is poor (×).

[0036] (3) Component ratio of C Alloys 11 to 13 are a group with a varying C component ratio. In this group, the component ratios excluding C, Fe, and irreversible impurities other than the specific impurity elements, that is, Al and Cr, and the specific individual impurity elements (N, S, Si, Mn, and O) are, in weight %, within the range of Al (4.0 - 4.2%): Cr (15.2 - 15.3%): N (0.004 - 0.007%): S (0.0014 - 0.0017%): Si (0.006 - 0.007%): Mn (0.05 - 0.06%): O (0.005 - 0.007%). When C is 0.009% and 0.006% (alloys 12 and 13 respectively), both cold rolling properties and oxidation resistance are good (◎), but when C is relatively high at 0.013% (alloy 11, comparative alloy), it was found that the oxidation resistance is poor (×).

[0037] (4) Regarding the component ratio of N Alloys 14 to 16 are a group with a varying N component ratio. In this group, the component ratios excluding N, Fe, and irreversible impurities other than the specific impurity elements, that is, Al and Cr, and the specific individual impurity elements (C, S, Si, Mn, and O) are, in weight %, within the range of Al (3.9 - 4.2%): Cr (15.0 - 15.4%): C (0.004 - 0.005%): S (0.0013 - 0.0015%): Si (0.004 - 0.005%): Mn (0.07 - 0.08%): O (0.005 - 0.007%). When N is 0.009% and 0.007% (alloys 15 and 16 respectively), both cold rolling properties and oxidation resistance are good (◎), but when N is relatively high at 0.012% (alloy 14, comparative alloy), it was found that the oxidation resistance is poor (×).

[0038] (5) Regarding the component ratio of S Alloys 17 to 19 are a group with a varying S component ratio. In this group, the component ratios excluding S, Fe, and irreversible impurities other than the above-specified impurity elements, that is, Al and Cr, and specific individual impurity elements (C, N, Si, Mn, and O) are, in weight %, within the range of Al (3.9 to 4.2%): Cr (14.9 to 15.3%): C (0.004 to 0.006%): N (0.006 to 0.008%): Si (0.005 to 0.007%): Mn (0.05 to 0.07%): O (0.004 to 0.007%). When S is 0.0018% and 0.0014% (alloys 18 and 19 respectively), both the cold rolling property and the oxidation resistance are good (◎), but when S is relatively high at 0.0022% (alloy 17, comparative alloy), it was found that the oxidation resistance is poor (×).

[0039] (6) Regarding the component ratio of Si Alloys 20 to 22 are a group with a varying Si component ratio. In this group, the component ratios excluding Si, Fe, and irreversible impurities other than the above-specified impurity elements, that is, Al and Cr, and specific individual impurity elements (C, N, S, Mn, and O) are, in weight %, within the range of Al (3.9 to 4.1%): Cr (15.1 to 15.4%): C (0.004 to 0.007%): N (0.005 to 0.007%): S (0.0014 to 0.0017%): Mn (0.05 to 0.07%): O (0.005 to 0.006%). When S is 0.008% and 0.005% (alloys 21 and 22 respectively), both the cold rolling property and the oxidation resistance are good (◎), but when Si is relatively high at 0.012% (alloy 20, comparative alloy), it was found that the oxidation resistance is poor (×).

[0040] (7) Regarding the component ratio of Mn Alloys 23 to 25 are a group with a varying Mn component ratio. In this group, the component ratios excluding irreversible impurities excluding Mn, Fe, and the above-specified impurity elements, that is, Al and Cr, and the respective specified impurity elements (C, N, S, Si, and O) are, by weight%, within the range of Al (4.0 to 4.2%): Cr (14.9 to 15.2%): C (0.005 to 0.007%): N (0.005 to 0.008%): S (0.0013 to 0.0015%): Si (0.004 to 0.007%): O (0.004 to 0.007%). When Mn is 0.09% and 0.06% (alloys 24 and 25 respectively), both the cold rolling property and the oxidation resistance are good (◎). However, when Mn is relatively high at 0.12% (alloy 23, comparative alloy), it was found that the oxidation resistance is poor (×).

[0041] (8) Regarding the component ratio of O Alloys 26 to 28 are a group with a varying O component ratio. In this group, the component ratios excluding irreversible impurities excluding O, Fe, and the above-specified impurity elements, that is, Al and Cr, and the respective specified impurity elements (C, N, S, Si, and Mn) are, by weight%, within the range of Al (3.9 to 4.2%): Cr (15.1 to 15.2%): C (0.004 to 0.006%): N (0.005 to 0.008%): S (0.0013 to 0.0017%): Si (0.005 to 0.007%): Mn (0.06 to 0.08%). When O is 0.008% and 0.005% (alloys 27 and 28 respectively), both the cold rolling property and the oxidation resistance are good (◎). However, when O is relatively high at 0.012% (alloy 26, comparative alloy), it was found that the oxidation resistance is poor (×).

[0042] (9) Summary As described above, from the measurement results and evaluation results in Table 1, the component ratio excluding irreversible impurities excluding Fe and the following specific impurity elements, that is, Al and Cr, and the respective specific impurity elements (C, N, S, Si, Mn, and O) are, in weight %, Al (2.0 to 6.0%): Cr (9.0 to 23.0%): C (0.010% or less): N (0.010% or less): S (0.0020% or less): Si (0.010% or less): Mn (0.10% or less): O (0.010% or less). It has been shown that the Fe-Cr-Al alloy within this range has multiple excellent effects simultaneously compared to alloys outside this composition ratio range.

Industrial Applicability

[0043] The Fe-Cr-Al alloy of the present invention is excellent in cold rolling property and also excellent in oxidation resistance, so it is suitable for use as oxidation-resistant members such as combustors of various engines and turbines. By using the Fe-Cr-Al alloy of the present invention, it becomes possible to improve the service temperature of thin plate members used at high temperatures such as combustors of gas turbines.< / cr> < / al>

Claims

1. The content of each of the following elements is in mass%, Al: 2.0 to 6.0%, Cr: 9.0 to 23.0%, C: 0.010% or less, N: 0.010% or less, S: 0.0020% or less, Si: 0.010% or less, Mn: 0.10% or less, O: 0.010% or less, and the balance consists of Fe and unavoidable impurities excluding the above elements, an Fe—Cr—Al alloy.

2. The content of each of the following elements is in mass%, Al: 2.0 to 6.0%, Cr: 9.0 to 23.0%, C: 0.010% or less, N: 0.010% or less, S: 0.0020% or less, Si: 0.010% or less, Mn: 0.10% or less, O: 0.010% or less, and rare earth elements are not added, and the balance consists of Fe and unavoidable impurities excluding the above elements, an Fe—Cr—Al alloy.

3. The Fe—Cr—Al alloy according to claim 1 or 2, which does not crack even when cold-rolled to a thickness of 0.4 mm without intermediate annealing when processed into a test piece having a thickness of 12 × 100 × 5 mm.

4. When processed into a test piece with a thickness of 12 × 30 × 2 mm, even when treated at 1300 °C for 100 hours in the atmosphere, the weight gain of the test piece is less than 5.0 mg / cm ２ The Fe—Cr—Al based alloy according to claim 1 or 2, which has a weight gain of less than 5.0 mg / cm

5. A thin plate member having a thickness of 50 μm to 2 mm, comprising the Fe—Cr—Al alloy according to claim 1 or 2.

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