JPH0649603A - Fe-cr alloy excellent in workability and high temperature strength - Google Patents

Abstract

(57) [Summary] [Objective] To provide a Fe-Cr alloy excellent in workability and high-temperature strength, as well as an Fe-Cr alloy excellent in acid resistance and oxidation resistance. [Structure] 3% by weight ≤ Cr ≤ 60% by weight, C + N + O + S
+ P ≦ 100 ppm, 0.01% by weight ≦ Ti + Nb + Z
Fe-Cr with r + V + Ta + W + 50B ≦ 6% by weight
alloy. Further, in addition to the above, 0.01% by weight ≦ Ni + C
Fe-Cr alloy with o + 2Cu ≦ 6% by weight. further,
In addition to the above, 0.1 wt% ≦ 3Al + 2Si + Mn ≦ 5
0% by weight and / or 0.001% by weight ≦ 4Ca + 4
Fe-Cr alloy with Mg + REM ≦ 0.2% by weight.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a Fe-Cr alloy excellent in workability and high temperature strength. The present invention also has excellent acid resistance and / or oxidation resistance in addition to workability and high temperature strength.
It relates to an e-Cr alloy.

[0002]

2. Description of the Related Art Generally, Fe--Cr alloy is known as a material having excellent corrosion resistance, but various improvements such as corrosion resistance and workability of the Fe--Cr alloy have been proposed as shown below. ing.

In Japanese Examined Patent Publication No. 63-58904, an Fe-Cr alloy having a Cr content of 11.0 to 16.0% by weight, particularly a ferritic stainless steel having a Ti content as a specific amount and being excellent in overhanging property and secondary workability Proposing steel.

Japanese Examined Patent Publication No. 64-6264 discloses a Fe-Cr alloy having a Cr content of 8.0 to 35.0% by weight, especially S
It proposes a stainless steel bright annealed material containing i, Mn and Nb in specific amounts and having excellent body rusting property.

According to Japanese Examined Patent Publication No. 2-1902, an Fe-Cr alloy having a Cr content of more than 20.0% by weight and 25% by weight or less, in particular, Mo, Mn and Nb each containing a specified amount of high temperature resistance during welding. We propose a corrosion-resistant ferritic stainless steel with excellent crackability and weld toughness.

In Japanese Patent Laid-Open No. 61-186451, Cr is used.
Fe-Cr alloy with a content of 25 to 50% by weight, especially S
It proposes an alloy containing i, Mn and Mo in specific amounts and having excellent sour resistance.

In JP-A-62-267450, a high-purity ferritic stainless steel which is a Fe-Cr alloy having a Cr content of 16 to 19% by weight, and in particular containing a specific amount of Mo and having excellent intergranular corrosion resistance. Is proposed.

In Japanese Patent Laid-Open No. 1-287253, Fe-C having a Cr content of 15 to 26% by weight and an Al content of 4 to 6% by weight.
It is an r-Al alloy, and proposes an Al-containing ferritic stainless steel containing a small amount of a rare earth element and having excellent oxidation resistance and manufacturability.

According to Japanese Patent Laid-Open No. 2-232344, a Fe-Cr alloy having a Cr content of 25.0 to 30.0% by weight, in which a specific amount of Mo is contained, is excellent in component adhesion resistance and seawater resistance. Ferritic stainless steel is proposed.

In Japanese Patent Laid-Open No. 3-2355, the Cr content is 1
A ferritic stainless steel having a Fe-Cr alloy content of 6.0 to 25.0% by weight, particularly containing Nb in a specific amount in the ratio of the total amount of C and N and having excellent cold workability, toughness, and corrosion resistance. Proposing steel.

[0011]

In these Fe-Cr alloys, since the corrosion resistance is important first, Cr is used in a relatively large amount. As a result, ductility decreases, workability is not always sufficient, and it becomes difficult to finish it into a desired shape according to the application, and in many cases it cannot be used eventually. For example, when a pipe is formed and bent to be used for piping, a trouble such as breakage occurs during bending, and further improvement in workability has been desired.

Further, the strength at high temperature is not sufficient, and in applications exposed to high temperature such as exhaust gas for automobile exhaust gas, further improvement in high temperature strength and high temperature fatigue characteristics has been desired. Further, further improvement has been demanded for its use as a plant material for the chemical industry which requires acid resistance.

That is, the object of the present invention is to provide an Fe--Cr alloy having improved workability and strength at high temperature. Another object of the present invention is Fe- which is excellent in acid resistance and / or oxidation resistance in addition to workability and high temperature strength.
It is to provide a Cr alloy.

[0014]

As a result of intensive studies to achieve the above object, the present inventor has surprisingly found that the conventional Fe-
It was found that the Fe-Cr alloy, which was present in the Cr alloy with extremely small impurities such as C, N, O, P, and S, was extremely excellent in ductility.
It was found that an alloy obtained by adding a specific amount of at least one selected from Ti, Nb, Zr, V, Ta, W and B to a Cr alloy has an improved strength at high temperatures, and has completed the present invention. .

According to the present invention, the Cr content is 3 to 60% by weight, the total amount of C, N, O, P and S is 100 ppm or less, and selected from Ti, Nb, Zr, V, Ta, W and B. 1 or more types are included in an amount satisfying the following formula (1),
Provided is a Fe-Cr alloy excellent in workability and high-temperature strength, which is characterized by comprising the balance Fe and unavoidable impurities. 0.01 wt% ≦ Ti + Nb + Zr + V + Ta + W + 50B ≦ 6 wt% (1)

According to the present invention, the Cr content is 5-6.
0 wt%, the total amount of C, N, O, P and S is 100 pp
m or less, one or more selected from Ti, Nb, Zr, V, Ta, W and B is contained in an amount satisfying the following formula (1), and one or more selected from Ni, Co and Cu is further described below. Provided is an Fe-Cr alloy excellent in workability, high-temperature strength, and acid resistance, characterized in that it is contained in an amount satisfying the formula (2) and the balance is Fe and unavoidable impurities. 0.01 wt% ≦ Ti + Nb + Zr + V + Ta + W + 50B ≦ 6 wt% (1) 0.01 wt% ≦ Ni + Co + 2Cu ≦ 6 wt% (2)

According to the present invention, the Cr content is 3-6.
0% by weight, the total amount of C, N, O, P and S is 100 p
pm or less, one or more selected from Ti, Nb, Zr, V, Ta, W and B is contained in an amount satisfying the following formula (1), and one or more selected from Al, Si and Mn is further described below. Amount satisfying formula (3) and / or Ca, Mg
And at least one selected from rare earth elements (REM) in an amount satisfying the following formula (4), and the balance Fe and unavoidable impurities, which are excellent in workability, high temperature strength and oxidation resistance. An Fe-Cr alloy is provided. 0.01 wt% ≦ Ti + Nb + Zr + V + Ta + W + 50B ≦ 6 wt% (1) 0.1 wt% ≦ 3Al + 2Si + Mn ≦ 50 wt% (3) 0.001 wt% ≦ 4Ca + 4Mg + REM ≦ 0.2 wt% (4)

Further, the Cr content is 5 to 60% by weight, and C,
The total amount of N, O, P and S is 100 ppm or less, T
i, Nb, Zr, V, Ta, W and B are contained in an amount satisfying the following formula (1), and N
One or more selected from i, Co and Cu is contained in an amount satisfying the following formula (2), and Al, Si and Mn are further contained.
Containing one or more selected from the following formula (3) and / or one or more selected from Ca, Mg and rare earth elements (REM) in an amount satisfying the following formula (4),
F excellent in workability, high temperature strength, acid resistance and oxidation resistance, characterized by being composed of balance Fe and unavoidable impurities
An e-Cr alloy is provided. 0.01 wt% ≦ Ti + Nb + Zr + V + Ta + W + 50B ≦ 6 wt% (1) 0.01 wt% ≦ Ni + Co + 2Cu ≦ 6 wt% (2) 0.1 wt% ≦ 3Al + 2Si + Mn ≦ 50 wt% (3) 0. 001 wt% ≦ 4Ca + 4Mg + REM ≦ 0.2 wt% (4)

[0019]

The present invention will be described in more detail below. (I) First, F of the present invention excellent in workability and high-temperature strength
The e-Cr alloy will be described. Figure 1 shows Fe-18% C
The total amount of C, N, O, P and S of the r alloy and the result of the tensile test at room temperature are shown based on the conventional alloy having the total amount of about 500 ppm. It can be seen that when the content is 100 ppm or less as compared with the conventional alloy, the elongation value is improved, the yield strength is remarkably reduced, and the ductility is improved. In FIG. 1, the change in elongation (%) and the change in proof stress (yield strength) (N / mm ² ) are C + N + O + S + P = 500 p for each alloy component.
It shows the difference in tensile properties from those of pm. The basic tensile properties are as follows. Fe-18Cr, C + N + O + S + P = 500 ppm, elongation 30%, yield strength 330 N / mm ² Fe-30Cr, C + N + O + S + P = 500 ppm, elongation 25%, yield strength 450 N / mm ²

FIG. 2 shows (Ti + Nb + Zr + V + Ta +
It is a graph showing the relationship between the value of (W + 50B) and the increase in high temperature proof stress (900 ° C.). When the above value is 0.01% by weight or more, the increase in high temperature strength is 0.1 N / mm ² or more. It is clear that the strength at

Next, the composition of the alloy of the present invention will be described. Cr: 3 to 60% by weight, preferably 5 to 45% by weight. Within the above range, in combination with other conditions of the present invention,
Although the alloy has excellent oxidation resistance, an excessive content of more than 60% by weight is not preferable because of high cost.

C, N, O, P, S: The total amount of these elements is 100 ppm or less, preferably 85 ppm or less. This improves the ductility of the alloy, that is, the workability, and at the same time, combines it with the conditions of the Cr content defined above and provides excellent oxidation resistance. If this amount exceeds 100 ppm, such an excellent effect is not exhibited.

Ti, Nb, Zr, V, Ta, W and B: One or more of these elements are contained and the content thereof is added so as to satisfy the following formula (1), preferably formula (1a). 0.01 wt% ≦ Ti + Nb + Zr + V + Ta + W + 50 × B ≦ 6 wt% …… (1) 0.1 wt% ≦ Ti + Nb + Zr + V + Ta + W + 50 × B ≦ 4 wt% …… (1a) By containing these elements in the above range amount, at high temperature Strength is improved. However, if these elements are excessively blended and deviate from the range of the formula (1), the high temperature strength is maintained but the brittleness of the material is promoted.
Further, the content of Ti, Nb, Zr, V, Ta, W or B is preferably in the following ranges respectively. Ti: Ti ≦ 5 (C% + N%) Nb: 0.01 to 1% by weight Zr: 0.01 to 1% by weight V: 0.02 to 1% by weight Ta: 0.01 to 1% by weight W: 0 0.03 to 1% by weight B: 0.0003 to 0.3% by weight

The alloy of the present invention satisfying the above conditions is excellent in workability and excellent in high temperature strength, and therefore, it is suitable for applications such as automobile exhaust gas pipes which are accompanied by pipe forming and subsequent bending.

Fe-Cr as described above for (I) of the present invention
To produce an alloy, ultra-high purity electrolytic iron and electrolytic Cr are used as raw materials. The main impurity in any of the raw materials is oxygen, and in order to remove this oxygen, for example, 10 ⁻⁵ torr
The Fe-Cr alloy of the present invention can be manufactured by melting and casting under an ultrahigh vacuum of r or higher.

(II) Next, the Fe-Cr alloy of the present invention excellent in workability, high temperature strength and acid resistance will be described.
FIG. 1 shows the total amount of C, N, O, P and S and the result of the tensile test at room temperature for the Fe-18% Cr alloy, based on the conventional alloy having the total amount of about 500 ppm. . Compared with conventional alloys, its content is 100p
It can be seen that when it is pm or less, the elongation value is improved, the yield strength is remarkably lowered, and the ductility is indeed improved.

FIG. 2 shows (Ti + Nb + Zr + V + Ta +
It is a graph showing the relationship between the value of (W + 50B) and the increase in high temperature proof stress (900 ° C). When the above value is 0.01% by weight or more, the increase in high temperature proof stress becomes 0.1 N / mm ² or more, It is clear that the strength at

FIG. 3 is a graph showing the relationship between the total amount of C, N, P, O and S and the corrosion degree for the Fe-36% Cr-3.2% Co alloy, and the total amount is within 100 ppm. It is clear that the corrosion rate is extremely low.

FIG. 4 shows Fe-Cr-1.6% Ni-1.
FIG. 4 is a graph showing the relationship between the Cr content and the corrosion degree for a 4% Co alloy when the total amount of C, N, O, P and S is 100 ppm or less and when it exceeds 100 ppm. From Figure 2, C + N + O + P + S is 100ppm
It is clear that the following alloys have remarkably low corrosion rates as compared with alloys exceeding 100 ppm, and that the tendency is remarkable when the Cr content is 5% by weight or more.

FIG. 5 shows an Fe-38% Cr alloy (however, C
+ N + O + P + S = 62 ppm), Ni + Co
It is a figure showing the relation between + 2Cu and the degree of corrosion, Ni + Co
It has been clarified that when the value of + 2Cu is 0.01% by weight or more, the corrosion degree decreases.

FIG. 6 shows Fe-46% Cr-3.0% Co.
-1.2% Cu alloy (however, C + N + O + P + S = 64
ppm), Ti + Nb + Zr + Ta + V + W + 5
It is a figure which shows the relationship between the value (weight%) of 0B, and a corrosion degree,
It has been revealed that when the above value is 0.01% by weight or more, the degree of corrosion is low.

Next, the composition of the alloy of the present invention will be described. Cr: 5 to 60% by weight, preferably 10 to 40% by weight. When the Cr content is in this range, an alloy having excellent acid resistance can be obtained as described in the section [Operation]. Excessive Cr content is not preferable because it causes deterioration of workability. Further, the effect of improving acid resistance is saturated.

C, N, O, P, S: The total amount of these elements is 100 ppm or less, preferably 85 ppm or less. As explained in the section of [Operation], when the content is 100 ppm or less, it is combined with other conditions and has excellent high temperature strength,
It exhibits acid resistance and is excellent in workability.

Ti, Nb, Zr, V, Ta, W and B: One or more of these elements are contained, and the content thereof is added so as to satisfy the following formula (1), preferably formula (1a). 0.01 wt% ≦ Ti + Nb + Zr + V + Ta + W + 50B ≦ 6 wt% (1) 0.1 wt% ≦ Ti + Nb + Zr + V + Ta + W + 50B ≦ 4 wt% (1a) By containing the above range amount, the strength at high temperature is improved. However, if these elements are excessively blended and deviate from the range of the formula (1), the high temperature strength is maintained but the brittleness of the material is promoted. In addition, Ti, Nb, Zr, V,
The content of Ta, W or B is preferably in the following range. Ti: Ti ≦ 5 (C wt% + N wt%) Nb: 0.01 to 1 wt% Zr: 0.01 to 1 wt% V: 0.02 to 1 wt% Ta: 0.01 to 1 wt% W : 0.03 to 1% by weight B: 0.0003 to 0.3% by weight

Cu, Ni, Co; all of these elements are important and useful elements that have the effect of improving the acid resistance of the alloy. The alloy of the present invention contains one or more selected from these elements, and the amount thereof is within the range that satisfies the following formula.

0.01 wt% ≦ Ni + Co + 2Cu ≦ 6 wt% (2) Preferably, 0.05 wt% ≦ Ni + Co + 2Cu ≦ 5.0 wt% (2a) The blending amount of Ni, Co, Cu is the above. If it is less than the range, corrosion resistance is poor, and if it is more than the range, manufacturability of the alloy is poor.

The preferable contents of each of Ni, Co and Cu are as follows, for the same reason as above. Ni: 0.05 to 5.0% by weight Co: 0.05 to 5.0% by weight Cu: 0.05 to 2.5% by weight

The Fe--Cr alloy satisfying the above conditions is
It is excellent in workability and high-temperature strength, and exhibits outstanding properties in acid resistance.

The Fe-Cr alloy described in (II) of the present invention is used as a raw material for ultra-high purity electrolytic Fe, electrolytic Cr, electrolytic N.
i, electrolytic Cu, electrolytic Co, iodide method Ti, electrolytic reduction N
b, molten salt electrolysis Zr, reduction V, electrolysis Ta, electrolysis reduction W,
It can be produced by using high-purity ferroboron or the like.

The main impurity in any of the contents is oxygen, and in order to remove this oxygen, the Fe-Cr of the present invention is obtained by melting and casting under an ultrahigh vacuum exceeding 10 ^-5 torr, preferably 10 ^-7 torr. Alloys can be produced.

(III) Next, the Fe-Cr alloy of the present invention which is excellent in workability, high temperature strength and oxidation resistance will be described.
FIG. 1 shows the total amount of C, N, O, P and S and the result of the tensile test at room temperature for the Fe-18% Cr alloy, based on the conventional alloy having the total amount of about 500 ppm. . Compared with conventional alloys, its content is 100p
It can be seen that when it is pm or less, the elongation value is improved, the yield strength is remarkably lowered, and the ductility is indeed improved.

FIG. 2 shows (Ti + Nb + Zr + V + Ta +
It is a graph showing the relationship between the value of (W + 50B) and the increase in high temperature proof stress (900 ° C). When the above value is 0.01% by weight or more, the increase in high temperature proof stress becomes 0.1 N / mm ² or more, It is clear that the strength at

In FIG. 7, the total amount of C + N + O + P + S is 10
Oxidation resistance test results for Fe-Cr alloys of 0 ppm or more and 100 ppm or less (in air, 1350 k, 12 hr
It is a graph which shows the weight loss after scale removal. The total content of C, N, O, P, and S is 10 or more, which is equivalent to or better than the conventional stainless steel having a Cr content of 12 wt% or more.
When the content is 0 ppm or less, it is apparent that Cr content is 3% by weight or more, and the high purity reduces the Cr content to save resources.

FIG. 8 is a graph showing the results of an oxidation resistance test (1350 K in air, weight loss after 12 hr scale removal) for a Fe- (15-30)% Cr alloy.
It is clear that when (3Al + 2Si + Mn) is 0.1% by weight or more, the oxidation resistance is excellent.

FIG. 9 is a graph showing the results of an oxidation resistance test (1350 K in air, weight loss after removing 12 hr scale) for a Fe- (15-30)% Cr alloy.
It is clear that when (4Ca + 4Mg + REM) is 0.001% by weight or more, the oxidation resistance is excellent.

Next, the composition and embodiment of the alloy of the present invention will be described. The Fe-Cr alloy of the present invention, which has excellent workability, high-temperature strength, and oxidation resistance, has the following three aspects, each of which will be described.

(1) First embodiment of the present invention Cr: 3 to 60% by weight, preferably 5 to 45% by weight. Within the above range, in combination with other conditions of the present invention,
Although the alloy has excellent oxidation resistance, an excessive content of more than 60% by weight is not preferable because of high cost.

C, N, O, P, S: The total amount of these elements is 100 ppm or less, preferably 85 ppm or less. By thus reducing the content of these elements, the ductility of the alloy, that is, the workability is improved, and at the same time, the alloy having excellent Cr resistance is formed by combining with the conditions of the Cr content defined above. If this amount exceeds 100 ppm, such an excellent effect is not exhibited.

Ti, Nb, Zr, V, Ta, W and B: One or more of these elements are contained, and the content thereof is added so as to satisfy the following formula (1), preferably formula (1a). 0.01 wt% ≦ Ti + Nb + Zr + V + Ta + W + 50B ≦ 6 wt% (1) 0.1 wt% ≦ Ti + Nb + Zr + V + Ta + W + 50B ≦ 4 wt% (1a) By containing the above range amount, the strength at high temperature is improved. However, if these elements are excessively blended and deviate from the range of the formula (1), the high temperature strength is maintained but the brittleness of the material is promoted. In addition, Ti, Nb, Zr, V,
The content of Ta, W or B is preferably in the following range. Ti: Ti ≦ 5 (C wt% + N wt%) Nb: 0.01 to 1 wt% Zr: 0.01 to 1 wt% V: 0.02 to 1 wt% Ta: 0.01 to 1 wt% W : 0.03 to 1% by weight B: 0.0003 to 0.3% by weight

Al, Si, Mn: Contains one or more of these elements, the content of which is represented by the following formula (3), preferably (3)
It is added to satisfy a). 0.1 wt% ≦ 3Al + 2Si + Mn ≦ 50 wt% (3) 0.3 wt% ≦ 3Al + 2Si + Mn ≦ 30 wt% (3a) By containing these elements in the above range, the oxidation resistance is remarkably improved. However, if added excessively, 3Al +
If the value of 2Si + Mn exceeds 50% by weight, workability deteriorates, which is not preferable. In addition, the content of Al, Si or Mn is preferably in the following ranges respectively. Al: 0.1-4 wt% Si: 0.3-3 wt% Mn: 0.5-10 wt%

(2) Second embodiment of the present invention Regarding the Cr content, the contents of C, N, O, P and S, and the preferable contents of Ti and the like, what has been described in the first embodiment is also applied to this embodiment. It The alloy of the second aspect contains at least one selected from Ca, Mg and REM as described below.

Ca, Mg, REM: These elements are not essential components in the alloy of the present invention, but by containing them so as to satisfy the following formula (4), the oxidation resistance is further improved, and the desirable results are obtained. To get However, if these elements are contained excessively (4Ca + 4Mg + RE
If the value of M) exceeds 0.2% by weight, surface defects of the alloy are likely to occur, which is not preferable. 0.001% by weight ≦ 4Ca + 4Mg + REM ≦ 0.2% by weight (4) Further, the content of Ca, Mg or REM is preferably in the following range. Ca: 0.0002 to 0.03
Wt% Mg: 0.0003 to 0.03 wt% REM: 0.0005 to 0.15 wt%

The alloy of the present invention satisfying the above conditions is excellent in workability, and also excellent in high temperature strength and oxidation resistance, and therefore suitable for applications such as automobile exhaust gas pipes.

To produce the Fe-Cr alloy of the present invention, ultrahigh-purity electrolytic iron and electrolytic Cr are used as raw materials. The main impurity of any of the raw materials is oxygen, and the Fe—Cr alloy of the present invention can be produced by melting and casting under an ultrahigh vacuum higher than 10 ⁻⁷ torr to remove this oxygen.

(3) Third Aspect of the Invention An alloy satisfying both the conditions of the alloy of the first aspect of the invention and the conditions of the alloy of the second aspect of the invention detailed above, that is, the Cr content is 3 to 60% by weight, the total amount of C, N, O, P and S is 100 ppm or less, and T
i, Nb, Zr, V, Ta, W and B are contained in an amount satisfying the above formula (1), and S
It contains at least one selected from i, Mn and Al in an amount satisfying the above formula (3), and at least one selected from Ca, Mg and a rare earth element (REM) satisfies the above formula (4). The Fe-Cr alloy contained in a large amount is also an alloy having more excellent oxidation resistance and workability, and is preferably used for the above-mentioned applications.

Fe of the present invention including these three embodiments
In order to produce a —Cr alloy, ultra-high purity electrolytic iron, electrolytic chromium, zone melting method silicon, molten salt electrolytic manganese, molten salt electrolytic aluminum, molten salt electrolytic calcium, electrolytic reduced magnesium, electrolytic reduced rare earth metal are used as raw materials. . The main impurity of any of the raw materials is oxygen, and in order to remove this oxygen, the Fe-Cr of the present invention was obtained by melting and casting under ultra-high vacuum of higher than ^10-5 torr.
Alloys can be produced.

(IV) Finally, in addition to workability and high temperature strength,
The Fe-Cr alloy of the present invention having excellent acid resistance and oxidation resistance will be described. This alloy of the present invention has the alloy composition particularly excellent in acid resistance described in (II) and the alloy composition particularly excellent in oxidation resistance described in (III).
Therefore, only the mode will be shown below, and the detailed description is omitted because it is as described in (II) and (III).

Like the invention of (III), this invention has three aspects, C + N + O + P ≦ 100 ppm, and Cr:
5 to 60% by weight, and 0.01% ≦ Ti + Nb + Zr
In addition to + V + W + 50B ≦ 6%, only the changing portion will be described below for each mode. (1) First embodiment of the present invention One or more kinds selected from Ni, Co and Cu are contained in an amount satisfying the following formula (2). 0.01% by weight ≦ Ni + Co + 2Cu ≦ 6% by weight (2) One or more kinds selected from Si, Mn and Al are contained in an amount satisfying the following formula (3). 0.1% by weight ≤3Al + 2Si + Mn≤50% by weight (3)

(2) Second Aspect of the Present Invention One or more kinds selected from Ni, Co and Cu are contained in an amount satisfying the following formula (2). 0.01% by weight ≦ Ni + Co + 2Cu ≦ 6% by weight (2) One or more selected from Ca, Mg and a rare earth element (REM) are contained in an amount satisfying the following formula (4). 0.001% by weight ≦ 4Ca + 4Mg + REM ≦ 0.2% by weight (4)

(3) Third Embodiment of the Present Invention One or more kinds selected from Ni, Co and Cu are contained in an amount satisfying the following formula (2). 0.01% by weight ≦ Ni + Co + 2Cu ≦ 6% by weight (2) One or more kinds selected from Si, Mn and Al are contained in an amount satisfying the following formula (3). 0.1 wt% ≦ 3Al + 2Si + Mn ≦ 50 wt% (3) One or more selected from Ca, Mg and rare earth elements (REM) are contained in an amount satisfying the following formula (4). 0.001% by weight ≦ 4Ca + 4Mg + REM ≦ 0.2% by weight (4)

Since the manufacturing method of the alloy of the present invention is exactly the same as the above, detailed description will be omitted.

[0062]

EXAMPLES The present invention will be specifically described below based on examples. (Example 1) Corresponding to invention alloys 1 to 6 and comparative alloys 1 to 6 ...
... Corresponding to claim 1 The alloys having the compositions shown in Table 1 were melted by ultra-high vacuum electrolytic melting of 10 ^-5 Torr or more using ultra-high-purity electrolytic iron and a high-purity metal material produced by electrolysis.

This was heated to about 1200 ° C. and then hot-rolled to a thickness of about 5 mm, and finally cold-rolled to 1.0 to 2.0 ^t mm, followed by recrystallization and adjustment of the crystal grain size. Annealing 50
It was applied at 0 to 1100 ° C.

From this, tensile test pieces at room temperature and high temperature were cut out and subjected to respective tests in accordance with JIS (room temperature tensile test pieces were designated as JIS No. 5 and high temperature tension was measured by JIS.
According to G0567).

The oxidation test was conducted at 1350 k for 12 h on the sample of Table 1 prepared by melting high-purity metal under high vacuum.
The sample was heated in an electric furnace in an atmosphere of air and then cooled to room temperature, and the weight loss when the scale on the surface of the sample was removed was measured and used as an index of oxidation resistance. The results are shown in Table 2. Table 2
From the results, it is clear that the workability and the high temperature strength are remarkably improved in the composition range of the present invention as compared with the materials in the composition range of the comparative example.

(Example 2) Corresponding to the invention alloys 7 to 12 and the comparative alloys 7 to 9 ... Corresponding to claim 2 The test materials having the component ranges shown in Table 1 were put into a 100 kg high frequency induction heating ultra high vacuum melting furnace. It was made. These test materials were subjected to forging, cutting and hot rolling, followed by annealing and cold rolling to produce a steel plate having a thickness of 1.0 mm.

Then, from these materials, 1 mm ^t ×
A test piece of 50 mm x 50 mm was prepared and immersed in 5% HCl at 40 ° C for 24 hours. 40% H ₂ SO ₄ at 50 ° C for 24 hours. Immersion test was performed to determine the corrosion rate (g / m ² · hr). It was measured. The results are summarized in Table 2. From the results in Table 2, it is clear that in the component range of the present invention, the corrosion in the acid immersion test is significantly suppressed as compared with the materials in the component ranges of the comparative examples.

From these results, the Fe-Cr system (5≤C
r ≦ 60) alloy, the total content of C, N, O, P and S is 100 ppm or less, and one or more of Ca, Ni and Co is 0.01 wt% ≦ Co + Ni + 2Cu ≦
It is clear that an alloy excellent in acid resistance can be obtained by including it in the range of 6% by weight.

In addition to the above component systems, Ti, Nb, Z
One or more of r, V, Ta, W, and B is set to 0.
01 wt% ≦ Ti + Nb + Zr + V + Ta + W + 50B
It is clear that an alloy having more excellent acid resistance can be obtained by including it in the range of ≤6.0% by weight.

(Example 3) Corresponding to invention alloys 13 to 26 and comparative alloys 10 to 12 ... Corresponding to claim 3 The alloys having the compositions shown in Table 1 were used for ultra high purity electrolytic iron, electrolytic Cr and high purity metal materials. It was melted by ultra high vacuum melting at 10 ⁻⁷ Torr or more.

This was heated to about 1200 ° C., finished by hot rolling to a thickness of about 5 mm, and finally cold rolled to 1.0 to 2.0 ^t mm, for recrystallization and adjustment of the crystal grain size. Annealing 50
It was applied at 0 to 1100 ° C.

From this, tensile test pieces at room temperature and high temperature were cut out and subjected to respective tests in accordance with JIS (room temperature tensile test pieces were designated as JIS No. 5 and high temperature tension was measured by JI.
Performed at 900 ° C. according to SG0567).

The oxidation test was conducted at 1350k for 12 hours.
r, the sample was heated in an electric furnace in the atmosphere and then cooled to room temperature, and the weight loss when the scale on the surface of the test piece was removed was measured and used as an index of oxidation resistance. Table 2 shows the test results. It is clear from Table 2 that the oxidation resistance is greatly improved in the component range of the present invention as compared with the component range of the comparative example.

(Example 4) Inventive alloys 27 to 29 ... Corresponding to claim 4 The alloys having the compositions shown in Table 1 are used in the form of ultra-high-purity electrolytic iron, electrolytic Cr, and high-purity metal material to exceed 10 ^-7 Torr or more. It was melted by high vacuum melting.

This was heated to about 1200 ° C. and then hot-rolled to a thickness of about 5 mm, and finally cold-rolled to 1.0 to 2.0 ^t mm, for recrystallization and adjustment of crystal grain size. Annealing 50
It was applied at 0 to 1100 ° C. With respect to the obtained test material, the same 5% HCl, 40 ° C. corrosion degree, and 4
A 0% H ₂ SO ₄ , 50 ° C. corrosion degree, 900 ° C. high temperature tensile test was conducted and evaluated in the same manner. The results are shown in Table 2. Those within the scope of the present invention have clearly been shown to exhibit excellent properties.

(Changes in Elongation and Yield Strength) Changes in elongation and proof stress (yield strength) of the test materials obtained in all the above examples were examined. The change in elongation (%) and the change in proof stress (yield strength) (N / mm ² ) indicate the difference in tensile properties between each alloy component and that of C + N + O + S + P = 500 ppm. The basic tensile properties are as follows. Fe-18Cr, C + N + O + S + P = 500 ppm, elongation 30%, yield strength 330 N / mm ² Fe-30Cr, C + N + O + S + P = 500 ppm, elongation 25%, yield strength 450 N / mm ²

[0077]

[Table 1]

[0078]

[Table 2]

[0079]

[Table 3]

[0080]

[Table 4]

[0081]

[Table 5]

[0082]

[Table 6]

[0083]

[Table 7]

[0084]

[Table 8]

[0085]

[Table 9]

[0086]

[Table 10]

[0087]

INDUSTRIAL APPLICABILITY The alloy of the present invention is excellent in workability, strength at high temperature, or, in addition to these, excellent in acid resistance and / or oxidation resistance, and therefore, it is suitably used for applications such as automobile exhaust gas pipes.

[Brief description of drawings]

FIG. 1 relates to Fe-18% Cr alloy, C, N,
It is a graph which shows the relationship between the total amount of O, P, and S, and a tensile characteristic.

FIG. 2 is a graph showing the relationship between Ti + Nb + Zr + V + Ta + W + 50B and the increase in high temperature proof stress.

FIG. 3 is a graph showing the relationship between the total amount of C, N, P, O and S and the degree of corrosion.

FIG. 4 is a graph showing the relationship between the amount of Cr and the degree of corrosion.

FIG. 5 is a graph showing the relationship between Ni + Co + 2Cu and the degree of corrosion.

FIG. 6 is a graph showing the relationship between Ti + Nb + Zn + Ta + V + W + 50B and the degree of corrosion.

FIG. 7 is a graph showing the relationship between the Cr content and the weight loss after the oxidation resistance test.

FIG. 8 is a graph showing the relationship between (3Al + 2Si + Mn) and oxidation resistance.

FIG. 9 is a graph showing the relationship between (4Ca + 4Mg + REM) and oxidation resistance.

Front Page Continuation (72) Inventor Fusao Togashi, 1 Kawasaki-cho, Chuo-ku, Chiba, Chiba Prefecture Technical Research Division, Kawasaki Steel Co., Ltd. (72) Yoshihiro Yazawa, 1 Kawasaki-cho, Chuo-ku, Chiba Address Kawasaki Iron & Steel Co., Ltd.Technology Research Division (72) Inventor Yasushi Kato 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Kawasaki Iron & Steel Technology Research Division (72) Inventor Satoshi Owada Chuo-ku, Chiba City Kawasaki Town No. 1 Kawasaki Steel Corporation Technical Research Division

Claims (4)

[Claims] 1. A Cr content of 3 to 60% by weight, C, N, O,
The total amount of P and S is 100 ppm or less, and Ti and N
Excellent workability and high temperature strength characterized by containing at least one selected from b, Zr, V, Ta, W and B in an amount satisfying the following formula (1), and the balance being Fe and inevitable impurities. Fe-Cr alloy. 0.01 wt% ≦ Ti + Nb + Zr + V + Ta + W + 50B ≦ 6 wt% (1) 2. A Cr content of 5 to 60% by weight, C, N, O,
The total amount of P and S is 100 ppm or less, Ti, Nb, Z
One or more selected from r, V, Ta, W and B is contained in an amount satisfying the following formula (1), and further Ni, Co and C are included.
Fe- which is excellent in workability, high temperature strength and acid resistance, characterized in that it contains at least one selected from u in an amount satisfying the following formula (2), and the balance is Fe and unavoidable impurities.
Cr alloy. 0.01 wt% ≦ Ti + Nb + Zr + V + Ta + W + 50B ≦ 6 wt% (1) 0.01 wt% ≦ Ni + Co + 2Cu ≦ 6 wt% (2) 3. A Cr content of 3 to 60% by weight, C, N, O,
The total amount of P and S is 100 ppm or less, Ti, Nb,
An amount of at least one selected from Zr, V, Ta, W and B satisfying the following formula (1), and an amount of at least one selected from Al, Si and Mn satisfying the following formula (3). And / or Ca, Mg and rare earth elements (RE
F which is excellent in workability, high temperature strength and oxidation resistance, characterized by containing at least one selected from M) in an amount satisfying the following formula (4), and the balance being Fe and inevitable impurities.
e-Cr alloy. 0.01 wt% ≦ Ti + Nb + Zr + V + Ta + W + 50B ≦ 6 wt% (1) 0.1 wt% ≦ 3Al + 2Si + Mn ≦ 50 wt% (3) 0.001 wt% ≦ 4Ca + 4Mg + REM ≦ 0.2 wt% (4) 4. A Cr content of 5 to 60% by weight, C, N, O,
The total amount of P and S is 100 ppm or less, Ti, Nb,
An amount containing one or more selected from Zr, V, Ta, W and B satisfying the following formula (1), and an amount containing one or more selected from Ni, Co and Cu satisfying the following formula (2). And / or C containing at least one selected from Al, Si and Mn and satisfying the following formula (3):
1 selected from a, Mg and rare earth elements (REM)
An Fe-Cr alloy excellent in workability, high temperature strength, acid resistance and oxidation resistance, characterized in that it contains at least one of the above-mentioned species in an amount satisfying the following formula (4), and the balance is Fe and inevitable impurities. 0.01 wt% ≦ Ti + Nb + Zr + V + Ta + W + 50B ≦ 6 wt% (1) 0.01 wt% ≦ Ni + Co + 2Cu ≦ 6 wt% (2) 0.1 wt% ≦ 3Al + 2Si + Mn ≦ 50 wt% (3) 0. 001 wt% ≦ 4Ca + 4Mg + REM ≦ 0.2 wt% (4)