JPS61119641A - Highly corrosion-resistant ni-base alloy and its production - Google Patents

Abstract

PURPOSE:To provide superior stress corrosion cracking resistance and hydrogen cracking resistance, by limiting the additive amounts of Al, Ti, and Nb within a specific range and by controlling the Si and Mn content, when manufacturing the precipitation strengthening type Ni-base alloy of combined addition system. CONSTITUTION:The highly corrosion-resistant Ni-base alloy consists of, by weight, <0.05% C, <0.15% Si, 0.3-2% Mn, 45-60% Ni, 18-27% Cr, 0.4-3.5% Ti, 2.5-5.5% Mo and/or <11% W(2.5%<=Mo+1/2W<=5.5%), <1.5% Al, <6.2% Nb and/or <2% Ta(Nb+1/2Ta<=6.2%), <0.25% P, <0.005% S, <0.05% N, and the balance Fe with inevitable impurities and satisfies (2Al+Ti+1/2 Nb<=3.5%).

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention provides excellent stress corrosion cracking resistance in a corrosive environment, particularly in an environment containing one or more of hydrogen sulfide, carbon dioxide, and chlorine ions. and a high-strength, high-toughness nickel foundation exhibiting hydrogen cracking resistance and a method for producing the same.

(Conventional technology) Conventionally, metal parts that require high strength and high corrosion resistance, such as structural materials for equipment in oil wells, chemical industries, geothermal power generation, etc., have been produced by (solid solution strengthening) + (cold working strengthening). ), it is difficult to increase the strength of metal parts with complex or special shapes that cannot be subjected to cold working etc. using the conventional methods described above. Ta.

On the other hand, a conventionally known means for increasing the strength that can be applied to members with special shapes is to add Ti and Al or Nb to the alloy composition.
This is to precipitate an intermetallic compound mainly composed of Al) (rl phase) or an intermetallic compound mainly composed of Ni3Nb (T" phase). Inconel -718, Inconel χ
There are Ni-based alloys such as -750 (trade name), but these conventional alloys have low Cr and high Ti, so Ni 3 T
i precipitates and deterioration of corrosion resistance is inevitable. For example, Inconel-718 is a γ° and γ" precipitation-strengthened Ni-based alloy with the addition of Nb, Ti, and Al, and is mainly precipitation strengthened by the T" phase, but it contains a considerable amount of Ti and has a large amount of N.
Corrosion resistance was not necessarily good due to precipitation of i 3 TL.

(Problems to be Solved by the Invention) By the way, for materials used in environments containing one or more of hydrogen sulfide, carbon dioxide, and chlorine ions, such as oil wells, chemical industries, geothermal power generation environments, etc. In addition to high strength and toughness, it requires excellent corrosion resistance, that is, resistance to stress corrosion cracking and resistance to hydrogen cracking. For materials used as structural materials in such applications, it is desirable to increase the strength of materials that are relatively easy to form, such as plates or pipes, by cold working, but for materials such as valves, joints,
For items such as piping that have a special shape that cannot be cold worked, the strength must be increased by precipitation strengthening.

However, the conventional alloys mentioned above, which are mostly T precipitation-strengthened Ni-based alloys by adding Ti and Al,
In precipitation strengthened alloys, according to the results of our research,
It was found that corrosion resistance is inherently susceptible to deterioration.

(Means for Solving the Problems) The applicant of this patent has developed a method for improving the corrosion resistance of the precipitation-strengthened Ni-based alloy, in place of the conventional Ti addition system.
Nb single addition system (Japanese Patent Application No. 58-109422) and Nb-M combined addition system (Japanese Patent Application No. 58-217774)
They each disclosed that they would adopt the following.

The present inventors continued their research and found that Ti
It has been found that even in the additive system (Nb, A (same as when combined with 2), Si, and Mn can be slightly adjusted, corrosion resistance can be dramatically improved, as well as toughness can be improved. In other words, the addition of Ti systems and Ti, Nb (
Alternatively, in A(2), a precipitation-strengthened Ni-based alloy with a composite addition system, Al, Ti, and Nb are 2A (2+Ti+1/
2Nb≦3.5% (7) Within the range By limiting the content of Si and Mn to SiS2.15% and 0.3%≦Mn≦2.0%, grain boundary strength can be improved. The present invention was completed based on the discovery that not only the corrosion resistance but also the toughness can be improved as a result of this.

Here, the gist of the present invention is as follows: c: 0.050% or less, Si: 0.15% or less, Mn: 0.30-2.0%, Ni: 45% by weight.
~60%, MO: 2.5-5.5% and W: 1
At least one type less than 1%, but 2.5%≦-〇1〃
At least one of W≦5.5%, A2: 1.5% or less, Nb: 6.2% or less, and Ta: 2.0% or less, however, Nb+V2Ta≦6.2%,
2A<2+Ti+! /GNb≦3.5%, P: 0.025% or less, S: 0.0050%
Hereinafter, N: 0.050% or less, and if necessary, Cu: 2.0% or less and Co
:15% or less of at least one species and/or 1? E
M: Q, 10% or less, Mg: 0.10% or less, Ca
It is a highly corrosion-resistant Ni-based alloy with excellent stress corrosion cracking resistance and hydrogen cracking resistance, having a composition of at least lpi of: 0.10% or less and Y: 0.20% or less, the remainder being Fe and incidental impurities.

Furthermore, the present invention has the following properties in weight%: C: 0.050% or less, Si: 0.15% or less, Mn: 0.30-2.0%, Ni: 45-45%.
60%, Cr: 18-27%, Ti: 0.
More than 40%, 3.5% or less, Mo: 2.5 to 5.5%
and W: at least one type of 11% or less, but 2.5
%≦)lo+1/2W≦5.5%, A(!: 1.5% or less, Nb: 6.2% or less and Ta: 2.0% or less, but Nb+V2Ta≦6.2%,
2Al+Ti+V2Nb≦3.5%, P 70.025% or less, S: 0.0050% or less, N 70.050% or less, and if necessary, Cu: 2.0% or less and Co
: 15% or less of at least one species and/or REM
: 0.10%↓lower, Mg: 0.10% or less,
An alloy having a composition consisting of at least one of Ca: 0.10% or less and Y: 0.20% or less, the remainder Fe and incidental impurities was subjected to hot working at 1200 to 800°C to a cross-section reduction rate of 50% or more. After, 900-12
After holding at 00°C for 3 minutes to 5 hours, cooling at a cooling rate higher than air cooling, and then aging treatment at 600 to 750°C for 1 to 200 hours once or twice.
This is a method for producing a highly corrosion resistant Ni-based alloy with excellent stress corrosion cracking resistance and hydrogen cracking resistance.

(Function) The reason why the alloy composition and processing conditions are limited as described above in the present invention will be explained in more detail below.

■) Chemical component C: hinders precipitation strengthening, and if it exceeds 0.050%, the amount of inclusions such as NbC and TiC increases, resulting in poor ductility and toughness.
Corrosion resistance deteriorates. Preferably C50,020%, but C50,010% further improves ductility, toughness and corrosion resistance.

Si: Si is usually added because it is effective as a deoxidizing agent, but when added in large amounts, it forms intermetallic compounds such as σ, μ, P, and Laves phases, which are unfavorable for ductility, toughness, and corrosion resistance (hereinafter referred to as TCP phase). It was thought that it would be easier to generate. However, the present inventors have discovered that Si further has the effect of promoting grain boundary precipitation of carbides, nitrides, carbonitrides, and the like. In some cases, this effect of Si is effective, but as a result of further research, in this alloy system, Mn
It has been found that by limiting SiS to 2.15% in combination with Ti, it is possible to suppress the above-mentioned grain boundary precipitation involving Ti, and it is possible to improve not only corrosion resistance but also toughness. Preferably it is 0.010 to 0.10%.

Mn: Mn is usually added as a sulfurizing agent, but TCP
It is not desirable to add a large amount because it may promote phase formation. However, it has been found that Mn has an effect completely opposite to that of Si, and in the range of Mn<0.30%, it may even promote grain boundary precipitation. Considering the suppression of grain boundary precipitation and TCP phase formation, the content is set to 0.30%≦Mn≦2°0%. Preferably 0.60%≦Mn≦1. It is Oo%.

Ni: The alloy in the present invention is basically strengthened by precipitating either T' phase or T' phase or both on an austenite base by aging, and contains Cr and Mo,
By balancing the amount of Fes Co added, it is necessary to have a sufficient amount of Ni to stabilize the austenite base so as not to generate a TCP phase, and for this purpose, the amount of Ni must be 45%. Furthermore, if Ni exceeds 60%, the hydrogen cracking resistance will deteriorate significantly, so 560% Ni is desirable.
%≦Ni≦55%.

Cr: Improves corrosion resistance together with Mo. For this purpose, a content of 18% or more is required, but if it exceeds 27%, hot workability deteriorates and TCP phases are more likely to be generated.

Preferably, Cr is 22-27%.

Ti: Ti is Ni3M (M
forms a γ phase or γ phase of Ti, Al, Nb) and contributes to an increase in strength. The precipitation ratio and amount of the 7' and T' phases vary depending on Ti, %, and the addition ratio and amount of Nb. Conventionally, when Ti is added in excess of 0.40%, Ni
It has been found that Ti forms 3 Ti and significantly deteriorates corrosion resistance, especially hydrogen cracking resistance, but in the present invention, as mentioned above, by slightly adjusting the amount of SisMn,
As long as Al+T<+1/2Nb<3.5%, adding more than 40% TiO can contribute to an increase in strength without deteriorating corrosion resistance. However, if more than 3.5% of Ti is added, the toughness may decrease significantly, so 0.4%<T
iS is set to 2.5%.

Mo, W: These elements particularly improve pitting corrosion resistance when coexisting with Cr. This effect is, for example, Mo 2.5%
This becomes noticeable with the above additions, but as with Cr, adding a large amount tends to generate a TCP phase (because Mo5.5%
The following additions are desirable. Although W exhibits the same effect as Mo, it is necessary to add twice the amount of Mo to obtain the same effect.

Therefore, at least part of the required Mo amount is W
You can also replace it with When W is added in excess of 11%, Mo
Similarly, since intermetallic compounds as described above are likely to be generated, the content is limited to 11% or less. Therefore, in the present invention, Mo: 2.5 to 5.5% and W 711%
At least 1ai below (however, 2.5%≦?lo+
1/2W≦5.5%).

Outside these ranges, corrosion resistance will not be improved sufficiently and ductility and toughness will deteriorate.

Shark, Nb, Ta: Al is an effective deoxidizing agent and is usually contained in an amount of 0.3% or less. However, by adding it as an alloying element as in the case of the present invention, Ni3M (M is Ti, Al, Nb) as in the case of Ti and Wb.
This also contributes to increased strength. For that, 0.3
Requires addition of more than %. However, since addition of a large amount of Al promotes TCP phase formation, M≦1.5% was set. In the present invention, Al of 0.3% or less is mixed in as a deoxidizing agent, and is not an alloying element to be actively added, but is a type of incidental impurity.

Nb is Ni3M (M is Ti
, A (2°Nb), which contributes to an increase in strength. Ti
The precipitation strengthening behavior or amount of precipitation of the T'' and T'' phases can be changed depending on the relative proportion to the amount of added Al, but if the Nb content exceeds 6.2%, the toughness decreases due to the formation of the TCP phase. Ta has a similar effect to Nb, so Nb
Although a part of Nb may be replaced with Ta, the effect of the addition is
It is almost A. Therefore, in the present invention, NbS2.2
% and TaS2.0%, Nb+1/2Ta≦6.2%
Add within the range.

Al. Nb and Ta are each added at least t +i within the above range, in which case, as already mentioned, 2 Kl + Ti + V2Nb≦3.5%.

P, S: P and S are impurities that are inevitably mixed in, and if they exist in large quantities in the alloy, they reduce hot workability due to grain boundary segregation and also deteriorate corrosion resistance, so they are not compatible with the present invention. P≦0.025%, S≦0.0050%, preferably S≦0.00 to further improve hot workability.
10%.

Since NUN increases the amount of inclusions and causes anisotropy in material properties, it is set to N≦0.050%, but in order to further dramatically improve ductility and toughness, it is preferably N≦0.0.
10%.

Fe: An appropriate amount is required to promote precipitation strengthening by balancing with the addition of Ni, and the remainder of the alloy composition is Fe, excluding incidental impurities. Preferably 3.0%≦Fe≦25
%.

Cu: Effective in improving corrosion resistance, but the effect is 2.0
If Cu exceeds 2.0%, saturation occurs, so Cu≦2.0%.

Co: Co also has the effect of improving corrosion resistance like Cu, but 1. Furthermore, in the case of Co, it particularly improves hydrogen cracking resistance. Furthermore, due to the balance with Ni%Fe, γ゛,
Go
It should be added within the range of ≦15%, but if it is added more than this, TC
P phase becomes easier to generate.

REM, Mg, Ca, Y2 These elements improve hot workability by adding at least one kind of trace amount, but each upper limit of 0.10%, 0.10%, 0.10% and 0.20%, respectively. On the contrary, if it exceeds this value, low melting point compounds tend to be produced and processability deteriorates.

Others: B, Sn, Zns, Pb, etc. do not affect the properties of the alloy obtained by the present invention in trace amounts, so up to 0.10% of each is allowed as impurities, but if this upper limit is exceeded, workability or corrosion resistance deteriorates. do.

Note that, as described above, Al as a deoxidizing agent may be contained up to 0.3%, but that amount of Al is also allowed as an impurity.

2) Hot processing When Nb is added as in the present invention, low melting point compounds tend to be generated at grain boundaries during solidification, and it is necessary to limit the heating temperature and processing temperature range during hot processing. be. When the starting temperature of hot working exceeds 1200°C, weakening of grain boundaries is observed. On the other hand, if the finishing temperature is less than 800°C, processing becomes difficult. In the present invention, therefore, 1
Temperature range from 200 to 800°C, preferably from 1150 to
Hot working is carried out at 850°C.

Furthermore, Nb, Mo, etc. tend to cause macro segregation during solidification, and if such segregation remains in products, it becomes a factor in deterioration of toughness and corrosion resistance in thick-walled materials.

For this reason, the degree of hot working from the ingot to the product is set to 50% or more in area reduction rate to prevent macro segregation of Nbs Mo and the like.

3) Appropriate solution treatment is necessary to effectively precipitate the γ° phase or T'' phase due to heat treatment aging. Therefore, in the present invention, prior to aging, the heating temperature is 900 to 12 ooC, preferably 950 °C. After holding at -1150℃ for 3 minutes to 5.0 hours, cool at a cooling rate faster than air cooling.Especially during cooling, the brittle phase tends to precipitate between 900 and 500℃, so the temperature range in between is 10℃/min. It is desirable to suppress the precipitation of such brittle phases by cooling at a cooling rate above.

4) Aging treatment This alloy has high strength, good ductility, toughness, and corrosion resistance because the γ° phase and/or γ“ phase are uniformly dispersed and precipitated in the austenite base matrix by aging. Precipitation strengthening behavior due to aging are solution treatment conditions and Ti, Al,
Precipitation becomes noticeable at an aging temperature of 600° C. or higher, although it varies depending on the amount of Nb added, as well as the amounts of Ni, Co, Pe, etc. added. High-temperature aging exceeding 750°C results in overaging, resulting in a decrease in strength and toughness due to agglomeration and coarsening of the RL phase or T'' phase, or the formation of the TCP phase.The selection of aging time varies depending on the aging temperature, but effective precipitation strengthening is Obtained in 1 to 200 hours. However, 5 to 200 hours.
Sufficient strength can be obtained even after 20 hours. It is also possible to perform the aging treatment two or more times, in which case the second and subsequent aging treatments may be performed by cooling to around room temperature after the previous aging treatment and then reheating, or The aging treatment may be performed by heating or cooling (at a faster rate than furnace cooling) from the treatment temperature to the next aging treatment temperature. No significant difference in strength, toughness or corrosion resistance was observed in either case.

Thus, according to the method of the present invention, the mechanical properties are 0.
．． 2% proof stress ≧63 kgf/crystal (preferably ≧77 k
gf/m e), elongation≧20%, aperture≧30% and impact value≧5kgf-a+/cd (preferably ≧10 kg
f-m/ai) and excellent corrosion resistance, that is, stress corrosion cracking resistance and hydrogen cracking resistance.

The alloy obtained by the present invention can obtain high strength by precipitation strengthening of the T° phase or T'' phase, so it is possible to obtain high strength by precipitation strengthening of the T° phase or T'' phase.
Even special-shaped products such as D-shaped products can be manufactured with good strength, toughness, and corrosion resistance.

Next, the present invention will be further explained by examples.

Last five weeks, alloys having the chemical compositions shown in Table 1 were prepared, and precipitation-strengthened nickel-based alloys were manufactured under the hot working conditions, heat treatment conditions, and aging treatment conditions shown in Table 2.

The mechanical properties and corrosion resistance test results of the obtained alloy are also summarized in Table 2.

In addition, each test condition was as follows.

・Tensile test: Test temperature: room temperature Test piece shape: diameter 3.5mm+, gauge distance 20n+
Charpy test: Test temperature: 20℃ Test piece shape: 5 x 10 x 55a++i, 2vo
'V with patch/stress corrosion cracking test: Corrosion solution: 25%Na C1-0,5%CH3C00
II-15ati H2S-10atm Co2
Solution pH 1 Temperature: 250℃ Immersion time 830 days Hydrogen cracking resistance test: NACE conditions; (5%Na C1-0,5%CH3
(C0OHlatm H2S, 25℃) Test piece shape: carbon steel coupling, RO, 25U notched As a comparative example, the alloy standard used in the method of the present invention has one or more of strength, ductility, toughness, or corrosion resistance. Two or more were not good.

Dimensions 37 to 43 are shown for comparison with Ti-added conventional alloys produced by the method of the present invention. Although many of these conventional alloys have good strength, they have poor corrosion resistance, and if such corrosion resistance is to be improved, strength must be sacrificed, and it is not possible to obtain good both.

In this way, by selecting the composition range of the alloy and the conditions of hot working, heat treatment, and aging treatment as in the present invention, it is possible to achieve high corrosion resistance, that is, excellent stress corrosion cracking resistance and hydrogen cracking resistance. A material with high strength and high toughness can be obtained.

Claims (8)

[Claims] (1) In weight%, C: 0.050% or less, Si: 0.15% or less, Mn:
0.30-2.0%, Ni: 45-60%, Cr: 18
~27%, Ti: more than 0.40%, 3.5% or less, Mo:
2.5-5.5% and W: at least 11% or less
Seeds: 2.5%≦Mo+1/2W≦5.5%, Al
: 1.5% or less, Nb: 6.2% or less, and Ta: 2.
At least one type of 0% or less However, Nb+1/2Ta≦
6.2%, 2Al+Ti+1/2Nb≦3.5%, P:
0.025% or less, S: 0.0050% or less, N: 0.
A highly corrosion-resistant Ni-based alloy with excellent stress corrosion cracking resistance and hydrogen cracking resistance, having a composition of 0.050% or less and the balance consisting of Fe and incidental impurities. (2) In weight%, C: 0.050% or less, Si: 0.15% or less, Mn:
0.30-2.0%, Ni: 45-60%, Cr: 18
~27%, Ti: more than 0.40%, 3.5% or less, Mo:
2.5-5.5% and W: at least 11% or less
Seeds: 2.5%≦Mo+1/2W≦5.5%, Al
: 1.5% or less, Nb: 6.2% or less, and Ta: 2.
At least one type of 0% or less However, Nb+1/2Ta≦
6.2%, 2Al+Ti+1/2Nb≦3.5%, Cu
: 2.0% or less and Co: 15% or less
Seed, P: 0.025% or less, S: 0.0050% or less, N:
A highly corrosion-resistant Ni-based alloy with excellent stress corrosion cracking resistance and hydrogen cracking resistance, having a composition of 0.050% or less and the balance consisting of Fe and incidental impurities. (3) In weight%, C: 0.050% or less, Si: 0.15% or less, Mn:
0.30-2.0%, Ni: 45-60%, Cr: 18
~27%, Ti: more than 0.40%, 3.5% or less, Mo:
2.5-5.5% and W: at least 11% or less
Seeds: 2.5%≦Mo+1/2W≦5.5%, Al
: 1.5% or less, Nb: 6.2% or less, and Ta: 2.
At least one type of 0% or less However, Nb+1/2Ta≦
6.2%, 2Al+Ti+1/2Nb≦3.5%, P:
0.025% or less, S: 0.0050% or less, N: 0.
050% or less, REM: 0.10% or less, Mg: 0.10% or less, Ca
A highly corrosion-resistant Ni-based alloy with excellent stress corrosion cracking resistance and hydrogen cracking resistance, having a composition consisting of at least one of Y: 0.10% or less and Y: 0.20% or less, the balance being Fe and incidental impurities. (4) In weight%, C: 0.050% or less, Si: 0.15% or less, Mn:
0.30-2.0%, Ni: 45-60%, Cr: 18
~27%, Ti: more than 0.40%, 3.5% or less, Mo:
2.5-5.5% and W: at least 11% or less
Seeds: 2.5%≦Mo+1/2W≦5.5%, Al
: 1.5% or less, Nb: 6.2% or less, and Ta: 2.
At least one type of 0% or less However, Nb+1/2Ta≦
6.2%, 2Al+Ti+1/2Nb≦3.5%, Cu
: 2.0% or less and Co: 15% or less
Seed, P: 0.025% or less, S: 0.0050% or less, N:
0.050% or less, REM: 0.10% or less, Mg: 0.10% or less, Ca
A highly corrosion-resistant Ni-based alloy with excellent stress corrosion cracking resistance and hydrogen cracking resistance, having a composition consisting of at least one of Y: 0.10% or less and Y: 0.20% or less, the balance being Fe and incidental impurities. (5) In weight%, C: 0.050% or less, Si: 0.15% or less, Mn:
0.30-2.0%, Ni: 45-60%, Cr: 18
~27%, Ti: more than 0.40%, 3.5% or less, Mo:
2.5-5.5% and W: at least 11% or less
Seeds: 2.5%≦Mo+1/2W≦5.5%, Al
: 1.5% or less, Nb: 6.2% or less, and Ta: 2.
At least one type of 0% or less However, Nb+1/2Ta≦
6.2%, 2Al+Ti+1/2Nb≦3.5%, P:
0.025% or less, S: 0.0050% or less, N: 0.
After hot working at 1200 to 800°C with a cross-section reduction rate of 50% or more to an alloy having a composition of 0.050% or less, the balance consisting of Fe and incidental impurities,
After holding at 00℃ for 3 minutes to 5 hours, cooling at a cooling rate higher than air cooling, then at 600 to 750℃ for 1 hour to 20 hours.
A method for producing a highly corrosion-resistant Ni-based alloy having excellent stress corrosion cracking resistance and hydrogen cracking resistance, which comprises performing a 0-hour aging treatment once or twice or more. (6) In weight%, C: 0.050% or less, Si: 0.15% or less, Mn:
0.30-2.0%, Ni: 45-60%, Cr: 18
~27%, Ti: more than 0.40%, 3.5% or less, Mo:
2.5-5.5% and W: at least 11% or less
Seeds: 2.5%≦Mo+1/2W≦5.5%, Al
: 1.5% or less, Nb: 6.2% or less, and Ta: 2.
At least one type of 0% or less However, Nb+1/2Ta≦
6.2%, 2Al+Ti+1/2Nb≦3.5%, Cu
: 2.0% or less and Co: 15% or less
Seed, P: 0.025% or less, S: 0.0050% or less, N:
After hot working at 1200 to 800°C with a cross-section reduction rate of 50% or more to an alloy having a composition of 0.050% or less, the balance consisting of Fe and incidental impurities, 900 to 12%
After holding at 00℃ for 3 minutes to 5 hours, cooling at a cooling rate higher than air cooling, then at 600 to 750℃ for 1 hour to 20 hours.
A method for producing a highly corrosion-resistant Ni-based alloy having excellent stress corrosion cracking resistance and hydrogen cracking resistance, which comprises performing a 0-hour aging treatment once or twice or more. (7) In weight%, C: 0.050% or less, Si: 0.15% or less, Mn:
0.30-2.0%, Ni: 45-60%, Cr: 18
~27%, Ti: more than 0.40%, 3.5% or less, Mo:
2.5-5.5% and W: at least 11% or less
Seeds: 2.5%≦Mo+1/2W≦5.5%, Al
: 1.5% or less, Nb: 6.2% or less, and Ta: 2.
At least one type of 0% or less However, Nb+1/2Ta≦
6.2%, 2Al+Ti+1/2Nb≦3.5%, P:
0.025% or less, S: 0.005% or less, N: 0.0
50% or less, REM: 0.10% or less, Mg: 0.10% or less, Ca
After hot working at 1200 to 800°C with a reduction in area of 50% or more to an alloy having a composition consisting of at least one of: 0.10% or less and Y: 0.20% or less, the balance being Fe and incidental impurities. , 900-12
After holding at 00℃ for 3 minutes to 5 hours, cooling at a cooling rate higher than air cooling, then at 600 to 750℃ for 1 hour to 20 hours.
A method for producing a highly corrosion-resistant Ni-based alloy having excellent stress corrosion cracking resistance and hydrogen cracking resistance, which comprises performing a 0-hour aging treatment once or twice or more. (8) In weight%, C: 0.050% or less, Si: 0.15% or less, Mn:
0.30-2.0%, Ni: 45-60%, Cr: 18
~27%, Ti: more than 0.40%, 3.5% or less, Mo:
2.5-5.5% and W: at least 11% or less
Seeds: 2.5%≦Mo+1/2W≦5.5%, Al
: 1.5% or less, Nb: 6.2% or less, and Ta: 2.
At least one type of 0% or less However, Nb+1/2Ta≦
6.2%, 2Al+Ti+1/2Nb≦3.5%, Cu
: 2.0% or less and Co: 15% or less
Seed, P: 0.025% or less, S: 0.0050% or less, N:
0.050% or less, REM: 0.10% or less, Mg: 0.10% or less, Ca
After hot working at 1200 to 800°C with a reduction in area of 50% or more to an alloy having a composition consisting of at least one of: 0.10% or less and Y: 0.20% or less, the balance being Fe and incidental impurities. , 900-12
After holding at 00℃ for 3 minutes to 5 hours, cooling at a cooling rate higher than air cooling, then at 600 to 750℃ for 1 hour to 20 hours.
A method for producing a highly corrosion-resistant Ni-based alloy having excellent stress corrosion cracking resistance and hydrogen cracking resistance, which comprises performing a 0-hour aging treatment once or twice or more.