JP2801837B2 - Fe-Cr alloy with excellent corrosion resistance - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to Fe--C having excellent corrosion resistance.
r alloy.

[0002]

2. Description of the Related Art Fe--Cr alloys are generally known as materials having excellent corrosion resistance. However, in Fe--Cr alloys, C, N, O and S may adversely affect corrosion resistance for the following reasons. Are known. C, N: appearance of Cr deficient layer due to formation of Cr carbonitride at grain boundaries. O, S: Increase in rusting point due to increase in inclusions.

That is, it is already known that the reduction of these impurity elements is effective in improving the corrosion resistance of an Fe—Cr alloy, and it is known that the reduction of C, N, O, S and Ti, N
Attempts have been made to remove the Cr-deficient layer by adding a carbonitride element such as b. The following describes conventional techniques for improving the corrosion resistance of Fe-Cr alloys.

Japanese Patent Application Laid-Open No. 61-186451 discloses that C
It proposes an alloy having an r content of 25 to 50% by weight, which is excellent in sour resistance, in which C and N are reduced to specific amounts and Si, Mn and Mo are contained in specific amounts. .

[0005] In Japanese Patent Publication No. 2-1902, Fe-C having a Cr content of more than 20.0% by weight and not more than 25.0% by weight is disclosed.
r alloys, in particular to reduce C and N and at the same time to reduce Mo and M
A corrosion-resistant ferritic stainless steel excellent in hot crack resistance and weld toughness during welding containing specific amounts of n and Nb has been proposed.

JP-A-3-2355 discloses an Fe—Cr alloy having a Cr content of 16.0 to 25.0% by weight,
Particularly, a ferritic stainless steel having excellent cold workability, toughness, and corrosion resistance in which Nb is contained in a specific amount in a ratio of the total amount of C and N is proposed.

[0007]

However, the effect of improving the corrosion resistance of Fe-Cr alloys proposed in these prior arts may still be insufficient. For example, building materials used in harsh corrosive environments such as near the coast, chemical plants, and exhaust gas materials for automobiles that require corrosion resistance at high temperatures require further improvement in corrosion resistance.

Attempts to add P to improve corrosion resistance have been made on ordinary steel, which has been put to practical use as weathering steel, and there are examples of application to Cr-containing steel. Is not enough.

That is, an object of the present invention is to provide a conventional Fe—C
Fe-Cr with more improved corrosion resistance than r alloy
To provide an alloy. It is an object of the present invention to provide highly corrosion-resistant steel suitable for stainless steel for building materials used in severe corrosive environments such as near the coast, stainless steel for chemical plants, and stainless steel for exhaust gas materials for automobiles.

[0010]

The inventor of the present invention has made intensive studies to achieve the above object, and as a result, the total amount of C, N, S and O existing as impurities in the conventional Fe-Cr alloy has been significantly reduced. At the same time, the Fe-Cr alloy containing a specific amount of P was found to be remarkably excellent in weather resistance.

The above-mentioned P-added Fe-Cr alloy has T
The addition of a specific amount of at least one selected from i, Nb, V, Zr, Ta, W and B further improves intergranular corrosion resistance, and the addition of a specific amount of Mo significantly improves pitting corrosion resistance. Found to improve. Also, N
It is found that the acid resistance is significantly improved by adding a specific amount of at least one selected from i, Co and Cu, and the oxidation resistance is improved by adding a specific amount of at least one selected from Al, Si and Mn. And found that the present invention was completed.

That is, according to the first aspect of the present invention,
Cr content is 5 to 60% by weight, the total amount of C, N, O and S is 100 ppm or less, and P content is 0.01 to 1.0.
The present invention provides an Fe—Cr alloy having excellent corrosion resistance, characterized in that the content is by weight and the balance is Fe and unavoidable impurities.

According to a second aspect of the present invention, in addition to the components of the first aspect, Al: 1.0% by weight or less;
An Fe—Cr alloy excellent in corrosion resistance containing i: 1.0% by weight or less and Mn: 1.0% by weight or less is provided.

According to a third aspect of the present invention, there is provided the method according to the first or second aspect, further comprising Ti, N
b, V, Zr, Ta, W and B, containing at least one selected from the group that satisfies the following formula (1):
An e-Cr alloy is provided. 0.01% by weight ≦ Ti + Nb + Zr + V + Ta + W + 20B ≦ 1.0% by weight (1)

Further, according to a fourth aspect of the present invention, in the first or second aspect, Mo: 0.
Fe-Cr with excellent corrosion resistance containing 0.5 to 20% by weight
An alloy is provided.

Further, according to a fifth aspect of the present invention, in the first aspect or the second aspect, Mo: 0.
The present invention provides an Fe-Cr alloy excellent in corrosion resistance, containing 0.5 to 20% by weight and containing at least one selected from Ti, Nb, V, Zr, Ta, W, and B satisfying the following formula (1). 0.01% by weight ≦ Ti + Nb + Zr + V + Ta + W + 20B ≦ 1.0% by weight (1)

According to a sixth aspect of the present invention, in the first, second, third, fourth or fifth aspects, one or more selected from Ni, Co and Cu are represented by the following formula: 2) Fe-Cr with excellent corrosion resistance contained in an amount satisfying
An alloy is provided. 0.01% by weight ≦ Ni + Co + 2Cu ≦ 6% by weight (2)

According to a seventh aspect of the present invention, in the above-mentioned first, third, fourth or fifth aspect, A
An Fe—Cr alloy excellent in corrosion resistance, containing one or more selected from 1, Si, and Mn in an amount satisfying the following formula (3) is provided. 1.0% by weight ≦ 3Al + 2Si + Mn ≦ 50% by weight (3)

Further, according to an eighth aspect of the present invention, in the first, third, fourth or fifth aspect, N is further added.
Fe, which contains at least one selected from i, Co and Cu in an amount satisfying the following formula (2), and contains at least one selected from Al, Si and Mn in an amount satisfying the following formula (3), has excellent corrosion resistance. -A Cr alloy is provided. 0.01% by weight ≦ Ni + Co + 2Cu ≦ 6% by weight (2) 1.0% by weight ≦ 3Al + 2Si + Mn ≦ 50% by weight (3)

[0020]

The present invention will be described below in more detail with reference to the drawings. FIG. 1 shows the relationship between the weather resistance and the total amount of C, N, O and S. This figure shows that the distance from the shore for the Fe-20% Cr-0.05% P alloy was 5 km from the coast in the coastal industrial area.
Atmospheric exposure for 6 months within 36m (exposed at an angle of 36 degrees southward)
After that, the results of visually evaluating the degree of rust on the following three scales are shown. 1: No rust 2: Stain-like corrosion occurred 3: Spot-like red rust occurred

The total amount of C, N, O and S is 100 pp
At m or less, no rusting is observed, and it is clear that the weather resistance is remarkably excellent.

FIG. 2 shows that the total amount of C, N, O and S is 1
Fe-18% Cr of not more than 00 ppm and not less than 100 ppm
FIG. 7 also shows the relationship between the rust degree and the P content after one year of exposure to the atmosphere for alloys. The degree of rust was visually evaluated on the following four scales. 1: light spot corrosion 2: whole spot corrosion 3: spot red rust with whole spot corrosion 4: whole red rust

FIG. 2 shows that the total amount of C, N, O and S is 1
It is clear that the Fe-Cr alloy of not more than 00 ppm has remarkably excellent weather resistance when the P content is 0.01% or more.

FIG. 3 shows the relationship between the total amount of C, N, O and S and the pitting potential (V ' _{C, 10} (mV vs SCE)) for the Fe-18% Cr-0.02% P alloy. It is. It is clear that when the total amount of C, N, O and S is 100 ppm or less, the pitting corrosion resistance is excellent.

As described above, as shown in FIGS.
When the total amount of O and S is extremely low and the content of P is higher than a certain value, the corrosion resistance of the Fe—Cr alloy is dramatically improved.

FIG. 4 shows that the total amount of C, N, O and S is 10
For the Fe-18% Cr-0.1% P alloy which is 0 ppm or less, the Mo content and the pitting corrosion potential (V ' _{C, 10} (mVvs
SCE)). It is clear that when the Mo content is 0.05% by weight or more, the pitting corrosion resistance is further excellent.

FIG. 5 shows that the total amount of C, N, O and S is 1
This shows the relationship between the degree of corrosion and the value of Ni + Co + 2Cu (% by weight) when immersed in boiling 1% HCl for 18 hours for Fe-20% Cr0.03% P alloy of not more than 00 ppm. It is clear that when the above value is 0.01% by weight or more, the corrosion degree is reduced and the acid resistance is improved.

FIG. 6 shows the total amount of C, N, O and S of 10
For a Fe-20% Cr-0.06% P alloy of 0 ppm or less, a repetitive oxidation test was performed in which one cycle of heating at 1075 ° C. for 30 minutes and cooling for 12 minutes was performed in the air, and the weight change was determined every 25 cycles. It is a graph showing the relationship between the number of cycles until measurement and oxidation above (the number of cycles when the weight gain of oxidation exceeds 5.0 mg / m ² ) and the value of 3Al + 2Si + Mn (% by weight). 3Al + 2S
When the value of i + Mn is 0.1% by weight or more, it is apparent that the oxidation resistance is remarkably excellent.

Hereinafter, the configuration of the present invention will be described in detail. More preferred embodiments of the invention and the advantages based thereon will become apparent.

(First Embodiment) Cr: 5 to 60% by weight, preferably 10 to 45% by weight. The Cr content within the above range is an essential condition for the alloy of the present invention to have excellent corrosion resistance. Excessive Cr content is undesirable because it causes a reduction in workability.

C, N, O and S: These elements are contained in the conventional Fe--Cr alloy as unavoidable impurities in total of several hundred ppm, but are not more than 100 ppm, preferably 85 ppm in the alloy of the present invention. The following is assumed. Such a reduction in the total amount of these elements is essential for the purpose of improving the corrosion resistance of the present invention. If the content exceeds 100 ppm, the object of the present invention is not achieved.

P: The alloy of the present invention has a P content of 0.01 to 1.0.
%, Preferably 0.015 to 0.3% by weight. By including P in the above range, the alloy of the present invention is provided with excellent corrosion resistance. However, 1.0
If the content exceeds% by weight, not only corrosion resistance is lowered but also toughness is lowered, which is not preferable because it causes a problem in production.

The Fe-content of the first embodiment of the present invention which satisfies the above-mentioned Cr content, the total amount of C, N, O and S, and the P content.
Since the Cr alloy is excellent in corrosion resistance, it is preferably used for applications such as building exterior materials and vehicle exterior materials.

(Second Embodiment) In addition to the components of the first embodiment, Al, Si and Mn added as deoxidizers
The composition of is added. That is, the steel ingot of the above component sufficiently satisfies the object of the present invention even when the amounts of Al, Si and Mn excessively administered are as follows. Al: 1.0% by weight or less. Preferably, not more than 0.5% by weight. Si: 1.0% by weight or less. Preferably, not more than 0.8% by weight. Mn: 1.0% by weight or less. Preferably, not more than 0.7% by weight.

The content of Al, Si and Mn exceeding the above range is not preferable because the deoxidizing effect is saturated. The Fe—Cr alloy of the second aspect of the present invention that satisfies the above is excellent in corrosion resistance, and is therefore preferably used for the same applications as in the first aspect.

(Third Aspect) In addition to the conditions of the first or second aspect, one or more selected from Ti, Nb, V, Zr, Ta, W and B are represented by the following formula (1), preferably An amount satisfying the following formula (1a) is contained. 0.01% by weight ≦ Ti + Nb + Zr + V + Ta + W + 20B ≦ 1.0% by weight (1) 0.03% by weight ≦ Ti + Nb + Zr + V + Ta + W + 20B ≦ 0.5% by weight (1a)

An alloy having excellent corrosion resistance can be obtained even if these elements are not added. By satisfying the above range, an alloy having further excellent intergranular corrosion resistance can be obtained, and at the same time, the corrosion resistance of the welded portion can be improved. I do. However, excessive addition of these elements is not preferable because workability is reduced due to solid solution strengthening of the added elements themselves. The content of each element is preferably within the following range for the same reason. Ti: 0.01 to 0.5% by weight Nb: 0.01 to 0.5% by weight Zr: 0.01 to 0.5% by weight V: 0.01 to 0.5% by weight Ta: 0.01 to 0.5% by weight 0.5% by weight W: 0.01 to 0.5% by weight B: 0.0003 to 0.01% by weight

The Fe of the third embodiment of the present invention, which satisfies the above,
Since the -Cr alloy is excellent in corrosion resistance, it is not only preferably used for the same applications as in the first aspect, but also excellent in corrosion resistance of the welded portion, and is particularly advantageous as a member to be welded.

(Fourth Aspect) In addition to the conditions of the first and second aspects, Mo is contained in an amount of 0.05 to 20% by weight, preferably 0.1 to 6.0% by weight. Even if Mo is not added, an alloy having excellent corrosion resistance can be obtained, but by satisfying the above range, an alloy having further improved pitting corrosion resistance and weather resistance can be obtained. Excessive addition of more than 20% by weight is not preferred because the material becomes hard and the toughness of the base material decreases. The Fe of the fourth aspect of the present invention that satisfies the above.
Since the -Cr alloy is excellent in corrosion resistance, it is preferably used for the same applications as in the first embodiment. Further, since it has excellent pitting corrosion resistance, it is preferably used for a water heater tube or the like.

(Fifth Aspect) The condition of the third aspect, which is particularly excellent in the corrosion resistance of the weld portion, is added to the condition of the fourth aspect, which is particularly excellent in the pitting corrosion resistance. That is, in addition to the conditions of the first or second embodiment, Mo: 0.05 to 20% by weight, preferably 0.1 to 6.0% by weight, and at the same time Ti, Nb, V, Zr, Ta, One or more selected from W and B are represented by the following formula (1), preferably the following formula (1)
a) It is contained in an amount satisfying (a). 0.01% by weight ≦ Ti + Nb + Zr + V + Ta + W + 20B ≦ 1.0% by weight (1) 0.03% by weight ≦ Ti + Nb + Zr + V + Ta + W + 20B ≦ 0.5% by weight (1a)

Ti, Nb, V, Zr, Ta, W and B
The preferred range of each individual element is as described in the third embodiment, and will not be described. The reasons for limiting the component ranges are the same as those described in the third and fourth embodiments, and a description thereof will be omitted. The Fe—Cr according to the fifth aspect of the present invention, which satisfies the above.
Since the alloy is excellent in corrosion resistance, it is preferably used as in the first embodiment or as a member requiring welding.

(Sixth Embodiment) In addition to the first, second, third, fourth or fifth embodiments, at least one selected from Ni, Co and Cu is represented by the following formula (2), preferably the following formula: (2a) It is contained in an amount satisfying. 0.01% by weight ≦ Ni + Co + 2Cu ≦ 6% by weight (2) 0.05% by weight ≦ Ni + Co + 2Cu ≦ 5% by weight (2a)

An alloy having excellent corrosion resistance can be obtained even if these elements are not added. However, by adding one or more of these elements in a specific amount, an alloy having further improved acid resistance and weather resistance can be obtained. . If the amount of Ni, Co and Cu is less than the above range, the acid resistance is poor, and if it is too large, the productivity of the alloy is poor. Preferred contents of Ni, Co and Cu are as follows, for the same reason as described 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 of the sixth embodiment of the present invention, which satisfies the above,
Since the -Cr alloy is excellent in corrosion resistance, it is preferably used not only in the same applications as in the first embodiment, but also in the acid resistance, and thus is preferably used as a material for chemical plants.

(Seventh Aspect) In addition to the first, third, fourth and fifth aspects, one or more selected from Al, Si and Mn may be represented by the following formula (3), preferably the following formula (3)
a) It is contained in an amount satisfying (a). 1.0% by weight ≦ 3Al + 2Si + Mn ≦ 50% by weight (3) 3.0% by weight ≦ 3Al + 2Si + Mn ≦ 20% by weight (3a)

In the seventh embodiment, Al, Si, and Mn are positively added, particularly for the purpose of improving oxidation resistance. Therefore, the purpose is essentially different from that of the second embodiment. Even if these elements are not added, an alloy having excellent corrosion resistance can be obtained, but by adding one or more of these elements in a specific amount, an alloy having further improved oxidation resistance can be obtained.
Excess content of more than 50% by weight should be avoided because oxide-based inclusions are scattered in the alloy, which lowers manufacturability and workability and makes it difficult to manufacture the alloy. The preferred contents of each individual element and the reasons are as follows. Al: 0.1 to 10.0% by weight When the content is less than 0.1% by weight, the effect is obtained, but not significant. 1
If the content exceeds 0.0% by weight, the decrease in productivity becomes noticeable. Si: 0.1 to 10.0% by weight Less than 0.1% by weight is effective, but not significant. 1
If the content exceeds 0.0% by weight, the decrease in productivity becomes noticeable. Mn: 0.1 to 20.0% by weight Less than 0.1% by weight is effective, but not significant. 2
If the content exceeds 0.0% by weight, the decrease in productivity becomes noticeable. The Fe—Cr alloy of the seventh aspect of the present invention, which satisfies the above, is excellent in corrosion resistance, so that it is not only preferably used for the same applications as in the first aspect, but also excellent in oxidation resistance at high temperatures, It is advantageous for exhaust gas materials.

(Eighth Aspect) The condition of the sixth aspect which is particularly excellent in acid resistance is added to the condition of the seventh aspect which is particularly excellent in oxidation resistance. That is, in addition to the first, third, fourth, or fifth aspects, at least one selected from Ni, Co and Cu is contained in an amount satisfying the following formula (2), preferably the following formula (2a). , Al, Si and Mn are contained in an amount satisfying the following formula (3), preferably the following formula (3a). 0.01% by weight ≦ Ni + Co + 2Cu ≦ 6% by weight (2) 0.05% by weight ≦ Ni + Co + 2Cu ≦ 5% by weight (2a) 1.0% by weight ≦ 3Al + 2Si + Mn ≦ 50% by weight (3) 3.0% by weight ≦ 3Al + 2Si + Mn ≦ 20% by weight (3a)

The preferred ranges of the individual elements and the reasons for limiting the component ranges are the same as those described in the sixth and seventh embodiments, and will not be described.

The alloys of the present invention shown in the first to eighth aspects can be obtained by melting and casting under a high vacuum using a predetermined amount of a high-purity raw material by an electrolytic method or the like. At this time, Al, Si and Mn may be used as the deoxidizing material. After smelting, the usual manufacturing process, namely smelting-hot rolling-annealing-pickling-
It can be manufactured by cold rolling-annealing- (pickling)-(temper rolling).

The alloy of the present invention is preferably made of Fe other than the above-mentioned components. However, Ca, Mg, R
Even if one or more of elements such as EM (rare earth element), Pb, Bi, Se, and Te are contained in a total amount of less than 1%, the effect can be sufficiently obtained.

Further, the effect of the alloy of the present invention can be sufficiently obtained regardless of whether the alloy is used as a hot-rolled annealed sheet or a cold-rolled annealed sheet, and the final surface finish is 2D, 2
The effect can be sufficiently obtained by any of B, BA, HL and polishing finish.

[0052]

The present invention will be specifically described below with reference to examples. (Example) 30 kg small steel ingots of various Fe-Cr alloys having the chemical compositions shown in Table 1 were melted in an ultra-high vacuum 50 kg high-frequency furnace. In smelting, the total amount of S, C, N, and O is 10
Maximum ultimate vacuum at room temperature is 1 to keep it below 0 ppm
An ultra-high vacuum furnace exceeding 0 ^-7 torr was used, and high-purity raw materials were used. In addition, in order to minimize the contamination of the crucible with impurity elements, the crucible was preliminarily dissolved and washed with ultra-high-purity iron by several charges, and then dissolved using strong stirring.

After cutting and removing 1 cm of the surface of each ingot,
After soaking for 1 hour at an optimum temperature selected in a temperature range of 0 to 1250 ° C., a hot-rolled sheet of 4 mm was formed and annealed for recrystallization. After cutting and removing the carbonitrided layer on the surface,
Cold rolling and recrystallization annealing were repeated once or twice and finally subjected to a test as a 0.7 mm cold-rolled annealed plate. If necessary, the surface layer was polished and removed before the test. The test pieces prepared in the above manner were subjected to various corrosion resistance tests by the methods described below.

(Weather resistance test) After conducting an atmospheric exposure test in the seaside industrial area for one year, (1) the appearance of the test piece was observed, and the degree of rust was evaluated as follows.
The evaluation was performed by categorizing into stages. 1: No rusting 2: Very slight spot corrosion 3: Slight spot corrosion 4: Spot rust formation together with spot corrosion 5: Large tendency to red rust

(2) The gloss retention was measured using a gloss meter (HG-246) manufactured by Suga Test Instruments, and the gloss ratio before and after exposure to the atmosphere was determined as the gloss retention. Gloss retention (%) = ΔGs (20) (after exposure) / Gs
(20) (Before exposure) x 100

(Intergranular Corrosion Resistance Test) JIS G 0575
The stainless steel was subjected to the sulfuric acid / copper sulfate test specified in the above, and the intergranular corrosion resistance was evaluated based on the presence or absence of cracks.

(Pit Corrosion Resistance Test) The pitting corrosion potential was measured in accordance with JIS G 0577. The pitting potential was represented by the potential at which the current density reached 10 μA / cm ² .

(Acid Resistance Test) After immersing the test piece in a boiling 0.5% HCl aqueous solution for 18 hours, the corrosion loss was measured, and the acid resistance was evaluated according to the following four grades. ◎: less corrosion rate 0.1g / m ² · hr ○: corrosion rate 0.1~1g / m ² · hr △: Corrosion of 1~3g / m ² · hr ×: corrosion rate 3g / m ² · hr or more

(Oxidation resistance test)
A repetitive oxidation test was performed with a cycle of heating for 0 minutes and cooling for 12 minutes as one cycle, the weight change was measured every 25 cycles, and the number of cycles until abnormal oxidation was caused (the oxidation weight gain exceeded 5.0 mg / m ² ). The number of cycles).

[0060]

[Table 1]

[0061]

[Table 2]

[0062]

[Table 3]

[0063]

[Table 4]

[0064]

[Table 5]

[0065]

[Table 6]

[0066]

[Table 7]

[0067]

[Table 8]

Hereinafter, the experimental results will be described. (Example 1) Fe-2 is shown in Tables 2, 3 and 4 respectively.
0% Cr alloy, Fe-11% Cr alloy, Fe-40% C
4 shows the results of a weather resistance test of an r alloy.

[0069]

[0070]

[0071]

From Tables 2, 3 and 4, it is clear that the alloys of the present invention are remarkably excellent in weather resistance. Those in which the total amount of C, N, O and S exceeds 100 ppm, and those in which P is out of the range of the present invention do not show excellent weather resistance.

Table 5 shows that Fe- (4-20)% Cr-
3 shows the results of a weather resistance test of a 0.1% P alloy.

[0074]

The alloy of the present invention having a Cr content of 5% by weight or more shows excellent weather resistance. Comparative alloy 6 having a Cr content of 4.8% by weight has a large degree of red rusting, and cannot be said to have a remarkably high gloss retention and excellent weather resistance.

(Example 2) Table 6 shows that Fe-20% Cr-
The results of a weather resistance test performed on a 0.02% P alloy are shown.

[0077]

[Table 9]

For example, Al, Si, Mn used as a deoxidizing material
, Even if the content is 1.0% or less, sufficient weather resistance can be obtained in combination with the conditions of the Cr content, the total amount of C, N, O and S, and the P content. It is clear that.

Example 3 Table 7 shows that Fe-11% Cr-
The results of a weather resistance test and an intergranular corrosion test performed on a 0.1% P alloy (C + N + O + S ≦ 100 ppm) are shown.

[0080]

Β = Ti + Nb + Zr + V + Ta + W + 2
If the value of OB is 0.01% by weight or more, the Cr content,
In combination with the conditions of the total amount of C, N, O and S and the P content, it is clear that not only weather resistance but also intergranular corrosion resistance is excellent.

Example 4 Table 8 shows that Fe-20% Cr-
(0.01-0.4)% P- (0.001-6)% Mo
4 shows the results of a weather resistance test and a pitting resistance test of the alloy.

[0083]

[Table 10]

It is apparent that the steel of the present invention, in which the Mo content is 0.05% by weight or more in addition to the conditions of the Cr content, the total amount of C, N, O and S, and the P content, is excellent in pitting corrosion resistance. It is. Comparative alloy 7 in which the total amount of C, N, O and S exceeds 100 ppm is inferior not only in weather resistance but also in pitting corrosion resistance.

(Example 5) Table 9 shows the results of the weather resistance test, the intergranular corrosion resistance test and the pitting corrosion resistance test of the inventive alloy 26 and the inventive alloy 27.

[0086]

In addition to the conditions of the Cr content, the total amount of C, N, O and S, and the P content, the Mo content, Ti + Nb
The alloy of the present invention that satisfies the range of + Zr + V + Ta + W + 20B is excellent in intergranular corrosion resistance and pitting corrosion resistance in addition to weather resistance.

(Example 6) Table 10 shows that Fe-20% Cr-
The results of a weather resistance test and an acid resistance test of a 0.02% P alloy (C + N + O + S <100 ppm) are shown.

[0089]

From the results shown in Table 10, it is clear that the acid resistance is improved when the Ni + Co + 2Cu value exceeds 0.01% by weight.

Example 7 Table 11 shows that Fe-20% Cr-
0.015% P alloy (C + N + O + S <100ppm)
4 shows the results of a weather resistance test and an oxidation resistance test for the present invention.

[0092]

From the results shown in Table 11, it is clear that when the value of 3Al + 2Si + Mn exceeds 1.0% by weight, the oxidation resistance is improved.

Example 8 Table 12 shows that Fe-20% Cr-
The results of a weather resistance test and an oxidation resistance test on a 0.02P alloy (C + N + O + S <100 ppm) are shown.

[0095]

From the results shown in Table 12, it is clear that, in the range of the eighth embodiment of the present invention, the oxidation resistance and the acid resistance are excellent.

[0097]

The Fe-Cr alloy of the present invention has excellent corrosion resistance and is therefore preferably used in general applications of Fe-Cr alloys.

[Brief description of the drawings]

FIG. 1 is a graph showing the relationship between weather resistance and the total amount of C, N, O and S.

FIG. 2 is a graph showing the relationship between weather resistance and P content.

FIG. 3 is a graph showing the relationship between pitting resistance and the total amount of C, N, O and S.

FIG. 4 is a graph showing the relationship between pitting corrosion resistance and Mo content.

FIG. 5 is a graph showing the relationship between acid resistance and Ni + Co + 2Cu value.

FIG. 6 is a graph showing a relationship between oxidation resistance and 3Al + 2Si + Mn number.

──────────────────────────────────────────────────続 き Continued on the front page (31) Priority claim number Japanese Patent Application No. 4-136778 (32) Priority date Hei 4 (1992) May 28 (33) Priority claim country Japan (JP) (72) Inventor Fusao Togashi 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Prefecture, Kawasaki Steel Engineering Co., Ltd. ) Inventor Tetsu Owada 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Kawasaki Steel Engineering Co., Ltd. Technical Research Division (56) References "Steel and Alloy Elements (2)" edited by the 19th Committee of Steelmaking, Japan Society for the Promotion of Science (Showa 41-3-25) Seibundo Shinkosha 49-53 (58) Fields investigated (Int.Cl. ⁶ , DB name) C22C 38/00-38/60 C22C 27/06 C22C 30/00

Claims (8)

(57) [Claims] 1. The method according to claim 1, wherein the Cr content is 5 to 60% by weight, C, N, O
And the total amount of S is 100 ppm or less, and the P content is 0.1 ppm.
Fe-C excellent in corrosion resistance characterized in that the content is from 0.01 to 1.0% by weight and the balance is Fe and unavoidable impurities.
r alloy. 2. The composition according to claim 1, further comprising Al: 1.0% by weight or less, Si:
The Fe-Cr alloy excellent in corrosion resistance according to claim 1, which contains 1.0% by weight or less and Mn: 1.0% by weight or less. 3. The corrosion-resistant F according to claim 1, further comprising at least one selected from Ti, Nb, V, Zr, Ta, W and B in an amount satisfying the following formula (1).
e-Cr alloy. 0.01% by weight ≦ Ti + Nb + Zr + V + Ta + W + 20B ≦ 1.0% by weight (1) 4. The Fe--Cr alloy according to claim 1, which contains 0.05 to 20% by weight of Mo. 5. Mo: 0.05 to 20% by weight and T
The Fe-Cr alloy excellent in corrosion resistance according to claim 1 or 2, comprising at least one selected from i, Nb, V, Zr, Ta, W and B in an amount satisfying the following formula (1). 0.01% by weight ≦ Ti + Nb + Zr + V + Ta + W + 20B ≦ 1.0% by weight (1) 6. The method according to claim 1, wherein at least one selected from Ni, Co and Cu is contained in an amount satisfying the following formula (2).
Fe-Cr excellent in corrosion resistance according to 2, 3, 4 or 5
alloy. 0.01% by weight ≦ Ni + Co + 2Cu ≦ 6% by weight (2) 7. The method according to claim 1, wherein at least one selected from Al, Si and Mn is contained in an amount satisfying the following formula (3).
3. The Fe—Cr alloy according to 3, 4, or 5, which is excellent in corrosion resistance. 1.0% by weight ≦ 3Al + 2Si + Mn ≦ 50% by weight (3) 8. At least one selected from Ni, Co and Cu is contained in an amount satisfying the following formula (2), and at least one selected from Al, Si and Mn is contained in an amount satisfying the following formula (3). The Fe-Cr alloy excellent in corrosion resistance according to claim 1, 3, 4, or 5. 0.01% by weight ≦ Ni + Co + 2Cu ≦ 6% by weight (2) 1.0% by weight ≦ 3Al + 2Si + Mn ≦ 50% by weight (3)