JPS589923A - Production of high strength oil well pipe of high stress corrosion cracking resistance - Google Patents

Abstract

PURPOSE:To obtain a high strength oil well pipe of high stress corrosion cracking resistance by contg. specific ratios of C, Si, Mn, P, Ni, Cr, etc. and working the steel thermally and mechanically under prescribed conditions. CONSTITUTION:The alloy consisting of <=0.05% C, <=1% Si, <=2% Mn, <=0.03% P, <=0.005% S, <=0.5% sol.Al, 25-60% Ni, 22.5-30% Cr, <8% Mo, and/or <16% W, or further <=2% Cu, and/or <=2% Co, and the balance Fe in addition to these and satisfying Cr(%)+10Mo(%)+5W(%)>=70%, 4%<=Mo(%)+1/2W(%)< 8% is produced by melting. Such alloy is subjected to a solution heat treatment under the conditions of holding the alloy for <=2hr at temps. between 260logC (%)+1,300 lower limit temp. and 16Mo(%)+10W(%)+10Cr(%)+777 upper limit temp. The alloy is cold worked at 10-60% fractional reduction in area.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing high-strength oil country tubular goods having excellent stress corrosion cracking resistance.

In recent years, due to the deterioration of the energy situation, there has been a marked tendency for oil and natural gas wells to become deeper;
Deep wells with a depth of 10,000 m or more have appeared.

Furthermore, due to similar circumstances, it is becoming increasingly difficult to extract oil and natural gas in a harsh corrosive environment containing humid hydrogen sulfide, as well as corrosive components such as carbon dioxide gas and chloride ions.

As oil and natural gas are drilled in such harsh environments, the oil country tubular goods used therein are required to have high strength and excellent corrosion resistance, especially resistance to stress corrosion cracking. .

As a general anti-corrosion measure for oil country tubular goods, it is known to introduce a corrosion suppressant called an inhibitor, but this method is often not effective for use in, for example, offshore oil wells.

From this point of view, consideration has recently begun to be given to the use of high-grade corrosion-resistant high-alloy steels such as stainless steel and Incoloy and Hastelloy (all trade names) for the production of oil country tubular goods. H2S
The details of the corrosion behavior of ``-Co2-CL'' in the oil well environment have not yet been fully elucidated, and the current situation is that it does not have the high strength required for oil country tubular goods for deep wells. be.

Therefore, from the above-mentioned viewpoint, the present inventors have developed a material with high strength and excellent stress resistance that can sufficiently withstand oil drilling in deep wells and severe corrosive environments (especially in 2S-Co2-cf oil well environments). As a result of conducting research to manufacture oil country tubular goods with corrosion cracking resistance, we found that (a) Stress corrosion cracking is the main cause of corrosion in the H2S -CO2-C1- environment; The behavior is completely different from that of general austenitic stainless steels. In other words, general stress corrosion cracking is deeply related to the presence of Ct-, whereas the above-mentioned oil well environment In addition to ct''', the influence of H2S is even greater.

(b) Steel pipes used for practical use as oil country tubular goods are generally:
Cold working is performed to improve strength, but cold working significantly reduces the resistance to stress corrosion cracking.

10- (C) The elution rate (corrosion rate) of steel in a H2S-Co2-ct'' environment depends on the contents of Cr, Ni, Mo, and W, and the corrosion resistance is improved by the surface film made of these components. and these components also increase its resistance to stress corrosion cracking, especially Mo
, and Mo is twice as effective as W. Therefore, Mo and W are 10 times more effective than Or (
%) + 10 Mo (@+5 W (%) 570%
.

4%≦Mo(%) -1-'4 W (a) <8chi.

If the following conditional expressions are satisfied, and the Ni content is 25 to 60 and the Cr content is 22.5 to 30, H2S-Co□- is extremely corrosive even when cold-worked.
It is possible to obtain a surface coating that exhibits excellent resistance to stress corrosion cracking in a Ct'' oil well environment, particularly in a harsh environment of 200° C. or less.

(d) Ni has the effect of increasing stress corrosion cracking resistance not only on the surface film but also on the structure.

(e) 0.05 to 0.3 of N as an alloying component
If the content is within this range, the strength of the pipe material will be further improved.

(f) S content as an unavoidable impurity is O, OOO
When the diameter is reduced to 7 inches or less, the hot workability of the tube material is significantly improved.

(g) P content as an unavoidable impurity is 0.003
% or less, hydrogen cracking susceptibility significantly decreases.

(h) Cu: 2% or less and Co as alloy components
; When containing one or two of the following:
Further improvement in corrosion resistance.

(1) Rare earth elements: 0.10% or less as alloy components;
Y: 0.20% or less, Mg: 0.10% or less,
When one or more of Ti: 0.5% or less and Ca: 0.10% or less are contained, hot workability is further improved.

(J) However, in order to ensure the desired high strength, an alloy with the above composition must be used with the empirical formula: 2601C@C (%) 4430
The lower limit temperature (6) calculated at 0 and the same empirical formula: 16
Mo(%9-1-10 W (%) + 10 C
r('l) +'i' Upper limit temperature calculated in 77 (6
) The carbide is completely dissolved in the solid solution by heat treatment at a temperature between
It is necessary to perform cold working at a wall thickness reduction rate of .

The findings shown in (a) to (J) above were obtained.

Therefore, this invention was made based on the above findings, and includes C: 0.05% or less, sl: 1.0% or less, Mn: 2.0% or less, and P: 0.030% or less.

Preferably, P:0 for the purpose of further improving hydrogen cracking resistance.
, 003% or less, S: 0.005% or less, preferably s: o, ooo' for the purpose of further improving hot workability.
I SOl, M: 0.5% or less, Ni:
25-60%.

Contains 22.5 to 30% of Cr, one or two of Mo: less than 8% and W: less than 16%,
Further, if necessary, N'20.05 to 0.3%.

Co: 2% or less, Co: 2% or less, rare earth element: 0.
10 or less, Y: 0.20% or less, Mg: 0.1
0% or less.

Ri・i:o, 5% or less, and Ca: 0. Contains one or more of the following, and has a composition in which the remainder consists of Fe and unavoidable impurities (above 21% by weight. All indications below 21 mean weight%), 13-cr(%)+l OMo(%)+5W(%)≧MaO%.

4chi≦Mo(a)±+Wshi)〈8%.

The alloy that satisfies the conditions is 2601ogC ('%) + 1
300"'C calculated lower limit temperature (6) and 16Mo
side) +l OW (After solution treatment at a temperature between the upper limit temperature (6) calculated from 10 to 10 Cr (%) + 7 pine for 2 hours or less, the wall thickness reduction rate of 10 to 60 inches This method is characterized by a method for manufacturing high-strength oil country tubular goods with excellent stress corrosion cracking resistance by cold working.

Next, in the method for manufacturing oil country tubular goods of this invention.

The reason why the component composition, solution treatment conditions, and wall thickness reduction rate during cold working are limited as described above will be explained below.

A. Component composition (a) C The lower the C content, the more the precipitation of carbides will be suppressed, so solution treatment can be carried out at a lower temperature, and this will increase the strength after cold working. It works more effectively. Therefore, it is desirable that the C content be as low as possible, but if the 14-C content exceeds 0.05%, intergranular stress corrosion cracking is likely to occur, so the upper limit was set at 0.05%. .

(b) 5i Sl is a necessary component as a deoxidizing component, but if its content exceeds 1.0%, hot workability will deteriorate, so its upper limit is set at 1.0%. Established.

(c) Mn The Mn component has a deoxidizing effect similar to Sl, and since the original component has little effect on stress corrosion cracking resistance, the upper limit value was set at a higher value of 2.0. It was determined that

(d) P The P component as an unavoidable impurity has a content of 0.0
If it exceeds 30%, the effect of increasing the stress corrosion cracking susceptibility appears, so it is necessary to set the upper limit to 0.030% to keep the stress corrosion cracking susceptibility in a low state. In addition, it has been found that as the P content is reduced, the hydrogen cracking resistance rapidly improves after reaching 0.00. When hydrogen cracking resistance is required, the P content is preferably 0.0030% or less.

(e) S The S component as an unavoidable impurity has a content of 0.0
If it exceeds 0.05%, it has the effect of deteriorating hot workability, so it is necessary to set the upper limit at 0.005% to prevent deterioration of hot workability. In this way, the S component has the effect of deteriorating hot workability when its content increases, but as the content is lowered, 0. On the contrary, reducing the S content to 7% will further improve hot workability, so if hot working under severe conditions is required, the S content should be 0.0007% or less. It is desirable to do so.

(f) At is effective as a deoxidizing component like Si and Mn, and even if it is contained up to 0.5% in sot, At content, it does not impair the characteristics of the pipe material in any way.
Its content was determined to be 0.5% or less in terms of soL and M content.

(ω N1 The N1 component has the effect of improving the stress corrosion cracking resistance of the pipe material, but if its content is less than 25%, the desired excellent stress corrosion cracking resistance cannot be secured. Even if the content exceeds 25%, no further improvement in stress corrosion cracking resistance will be obtained, and the content was set at 25 to 60%, taking economic efficiency into consideration.

(h) Cr The Cr component is a component that significantly improves stress corrosion cracking resistance when coexisting with Ni, Mo, and W components, but even if its content is less than 22.5%, hot workability is However, in order to ensure the desired stress corrosion cracking resistance, the content of Mo and W must be increased accordingly, which is economically disadvantageous. , its lower limit was set at 22.5%. −・
On the other hand, if the 4i'M content exceeds 30%, deterioration in hot workability cannot be avoided no matter how much the S content is reduced, so the upper limit was set at 30%.

(i) Mo and W 17- As mentioned above, these components have an equal effect of improving stress corrosion cracking resistance when coexisting with Ni and Cr, but Mo: 8% or more and W :H2S-C whose environmental temperature is below 200℃ even if it contains 16% or more
In the corrosive environment of O27ct-, no further improvement effect appeared, and considering economic efficiency, the respective contents were
o: E less than 1%, W: less than 16%. Also, M
Regarding the content of o and W, conditional expression: Mo (→++W%)
The reason why W is specified as 4% is because the atomic weight of W is about twice that of MO, and in terms of effectiveness, they are equal at about 10%.
If the value is less than 8%, the desired temporary stress corrosion cracking resistance cannot be obtained especially under the above-mentioned adverse environment of 200°C or less. ,
(7) Containment and Jl\fQ'l' PI ','
, Ill ', l'l+ 71 , +, 'l^・1°
The value of 1MLJ (%) + +Wφ) was set to be less than 4% to 8%.

(j) N Since the N component has a strength improving effect through solid solution strengthening, it is included as necessary when particularly high strength is required, but if the content is less than 0.05%, 18- desired It was not possible to obtain the strength improvement effect of 0.3%.
If the content exceeds 0.05%, it becomes difficult to melt and make ingots, so the content was set at 0.05 to 0.3%.

(k) Cu and CO These components have a uniform effect of improving the corrosion resistance of the pipe material, and CO also has a solid solution strengthening effect.
It is included as necessary, especially when even better corrosion resistance is required, but if CU exceeds 2 inches, hot workability will deteriorate.On the other hand, CO should not be included in excess of 2%. Since no further improvement effect could be seen even with the addition of 2% Cu and 2% Co, respectively.

(t) Rare earth elements, Y, Mg, Ti, and Ca
These components have a uniform effect of further improving hot workability, so they are included as necessary when hot working is carried out under severe conditions.Rare earth elements: 0.10% , Y:, 0.20%.

Even if the content exceeds Mg: 0110% + Tl: 0.5% + and Ca: 0.10%, no improvement effect on hot workability will be seen, and in fact, a deterioration phenomenon will appear.
From this, the content of each rare earth element:
0.10% or less, y: 0.20% or less, Ag: 0
．． 10% or less, Ti: 0.5% or less, and Ca: 0.
It was set at 10% or less.

(m) Cr (%) +10Mo (%) + 5
w (%) Figure 1 shows stress corrosion cracking resistance under severe corrosive environments.
5 shows the relationship between W (%) and Ni content. That is, Cr, Ni, Mo.

and Cr-N1-) with various W contents, i
o series.

Cr-Ni-W system, and Cr-Ni-h4o-
' W-based steel is melted, cast, forged, and hot-rolled to form a plate with a thickness of I*yx. This plate is then heated with a water-cooled solution after being held at a temperature of 1000°C for 30 minutes. After the oxidation treatment, cold working with a processing rate of 22% is applied for the purpose of improving strength, and the resulting steel plate is rolled perpendicularly to the rolling direction to a thickness of:
Cut out a test piece of 2 mm x width: 10 mm x length near 5 mm,
Regarding this test piece, using the three-point support beam jig shown in FIG. H2S and CO2 saturated with CO2 of 2
A stress corrosion cracking test was conducted by immersing the test piece in a 0% NaCt solution (temperature: 200°C) for 1000 hours, and after the test, the presence or absence of cracking in the test piece was observed. Based on these results, the inventors independently set a conditional expression: Cr(rostrum+1
It has become clear that there is a relationship shown in FIG. 1 between 0Mo (rostral +5W°C) and N1 content with respect to stress corrosion cracking resistance. In FIG. 1, ○ marks indicate no occurrence of mackerel, and X marks indicate occurrence of cracks. From the results shown in Figure 1, Cr(%)-1-1
0MO (fishing +5W (4) value is less than 70%, N1
It is clear that if the content is less than 25%, the desired excellent stress corrosion cracking resistance cannot be obtained.

In addition, in the alloy of this invention, B is included as an unavoidable impurity.
, Sn, Pb, and Zn each in an amount of 0.1 or less does not impair the properties of the alloy of the present invention. B. Solution treatment conditions and cold working conditions The high strength of the oil country tubular goods of this invention is achieved not only by the inclusion of alloying component 21-, but also by performing cold working after completely solid solutionizing the carbides. This is ensured by In this case, complete solid solution of carbide is 260■■C(9))±13
The lower limit temperature ('C) calculated in 00 and 16Mo (chi)
10 w (%) + 10 Cr (%) +'i”M
The upper limit temperature calculated in (It is measured by holding the temperature between 'Q for 2 hours or less, the formula for calculating the lower limit temperature above: 2601og C) and the formula for calculating the upper limit temperature: 16Mo (to) +10W((6)+10Cr(%
9 +77 'i' is determined empirically based on the results of numerous tests, and below the above lower limit temperature, carbide cannot be completely dissolved in solid solution, and undissolved carbide remains. As a result, susceptibility to stress corrosion cracking increases.
On the other hand, if the solution treatment temperature exceeds the above upper limit temperature or the holding time exceeds 2 hours, the crystal grains will become coarser and will not be as desired in subsequent cold working. Since it is not possible to obtain high strength, the solution treatment temperature and holding time were determined as described above.

In addition, in this invention, as described above, cold working is performed after the solution treatment to improve the strength, but if the cold working is less than 10% in wall thickness reduction rate, the desired strength cannot be secured. On the other hand, if cold working is performed at a wall thickness reduction rate exceeding 60 inches, the deterioration of ductility and toughness will be significant.
It was established that

By applying the above component composition and manufacturing conditions, we can produce oil country tubular goods that have high strength with a 0.2% proof stress of 80 kgf/m- or more, and have excellent stress corrosion cracking resistance as well as ductility and toughness. It can be manufactured.

Next, the method for producing oil country tubular goods according to the present invention will be specifically explained using examples and comparing with comparative examples.

In each of the examples, a molten metal having the composition shown in Table 1 was heated in a conventional electric furnace, an Ar-oxygen decarburization furnace (AOD furnace) for the purpose of desulfurization and N addition, and further dephosphorization as necessary. After melting using an electroslag melting furnace (ESR furnace) for the purpose of smelting, it was cast into an ingot with a diameter of 500 mm, and then hot forged at a temperature of 1200 ° C to this ingot to a diameter of 150 mm. A billet of φ is formed, and in this case, for the purpose of evaluating hot workability, it is observed whether or not cracks occur in the billet, and then the billet is subjected to hot extrusion processing. A raw pipe with a thickness of 4JII was formed, and then subjected to solution treatment and cold working under the same solution treatment conditions (cooling after treatment was water cooling in both cases) and wall thickness reduction rate as shown in Table 1. By subjecting the alloy tube materials 1 to 29 degrees of the present invention and the comparison alloy tube materials 1 to 8. and conventional alloy tube materials 1-4 were manufactured, respectively.

Comparative alloy tube materials 1 to 8 have a content of any one of the constituent components or one of the manufacturing conditions (indicated with an asterisk in Table 1) of the present invention. It was manufactured under conditions outside the range, and all conventional alloy tube materials had known compositions.
The same pipe material 1 is JI S-8US316, and the same pipe material 2 is JI S-8US316.
S-8US310S, 3I/i Incoloy SOO, and 4 have compositions corresponding to JIS/SUS 329Jl.

Next, the resulting alloy tube materials 1 to 29 of the present invention were prepared. Comparative alloy tube materials 1 to 8. And length of conventional alloy pipe material:
A 20 mm test piece was cut out, a portion corresponding to 60° was cut off along the length direction of the test piece, and a bolt was passed through the test piece in this state as shown in the front view in Fig. 3. A tensile stress equivalent to 0.2% proof stress was applied to the outer surface of the tube by tightening it with a nut, and the H2S partial pressure was set to 0.1 atm, 1 atm, and 20 atm, respectively, for the test piece S in this state. H2S - 10 atm CO2' - 20%N
A stress corrosion cracking test was conducted by immersing the sample in an aCt solution (liquid temperature: 200°C) for 1000 hours, and the presence or absence of stress corrosion cracking after the test was investigated. The results are shown in Table 2 together with the presence or absence of cracking during hot forging, the tensile test results, and the impact test results.

In Table 2, all marks ○ indicate those with no cracks, while marks X indicate those with cracks.

From the results shown in Table 2, comparative alloy tube materials 1 to 8 were inferior in at least one of the following properties: hot workability, stress corrosion cracking resistance, and strength. All of the alloy tube materials 1 to 29 of the present invention have excellent hot workability and stress corrosion cracking resistance, and also have high strength and good hot workability, but have relatively low strength. It is clear that the pipe materials have even better characteristics than the conventional alloy tube materials 1 to 4, which have a low stress corrosion cracking resistance and are inferior in stress corrosion cracking resistance.

As mentioned above, oil country tubular goods manufactured by the method of the present invention have particularly high strength and excellent stress corrosion cracking resistance, and are therefore suitable for oil and natural gas extraction in harsh environments where these properties are required. Of course, it also exhibits extremely excellent performance when used as geothermal well pipes.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the relationship between Ni content and Cr (@+10 Mo (%) + 5W (9)) regarding stress corrosion cracking resistance of alloys, and Figures 2 and 3 are for plate-like alloys. and 3 showing aspects of stress corrosion cracking tests on tubular specimens.
0- Diagram Applicant Sumitomo Metal Industries Co., Ltd. Agent Tomi 1) Kazuo Figure 1 Cr (% + IOMo (%) + 5W (%)) 31- Dormitory 2 Figure 3 Continuation of page 1 0 shots Akio Ikeda, Sumitomo Metal Industries, Ltd., Central Technical Research Laboratory, 1-3 Nishinagasu Hondori, Amagasaki City, Akio Ikeda, 1-3 Nishinagasu Hondori, Amagasaki City, 0 Name: Daiji Moroishi, Sumitomo Metal Industries, Ltd., Central Technology Research Laboratory, 1-3 Nishinagasu Hondori, Amagasaki City

Claims (1)

[Claims] (1) C: 0.05% or less, Si: 1.0% or less, Mn: 2.0% or less, P: 0.030% or less,
S: 0.005% or less, sol, AQ: 0.5
% or less, Ni: 25-60%, cr: 22.5-
30%, contains one or two of Mo: less than 8% and W: less than 16%, with the remainder consisting of Fe and unavoidable impurities (more than % by weight), and Cr (@ + 10Mo (@ + 5 W (Si)
≧'i'o%. 4chi≦Mo(@+4W(4)〈8%,
The lower limit temperature C) calculated at 0 and 16Mo (%) +1
0 W (%) + 10 Cr (at a temperature between the upper limit temperature (6) calculated by @ + Guf 7) 1 After solution treatment under the condition of holding for 2 hours or less at a time, 10
A method for producing high-strength oil country tubular goods having excellent stress corrosion cracking resistance, characterized by cold working at a wall thickness reduction rate of ~60%. (2) C: 0.05% or less, Si: 1.0%
Hereinafter, Mn: 2.0 or less, P: 0.030% or less,
S: 0.005% or less, sot, Ai: 0.5
% or less, Ni: 25 to 60%, Cr: 22.5 to 30%, Mo: less than 8% and W: less than 16%, and further contains Cu: 2%. Contains one or two of the following and CO: 2% or less, with the remainder consisting of Fe and unavoidable impurities (wt%), and Cr (@ + 10 Mo (@ + 5 W)
(%)≧70chi. 4%≦M○(%)++W part)〈8th section. An alloy that satisfies the conditions of 2601ogC (effectiveness +130
Lower limit temperature calculated at 0 (Rito, 16M0 (@-1-1
After solution treatment at a temperature between 0W←)+10Cr (at the upper limit temperature calculated by @+77'I) and holding for 2 hours or less, cold working at a wall thickness reduction rate of 10 to 60 inches. A method for producing high-strength oil country tubular goods with excellent stress corrosion cracking resistance (3) c: 0.05% JJ, lower, Si:
10% or less, Mn: 2.0 or less, P: 0.03
Q% or less, S: 0.005% or less, sol,
AQ: 0.5% or less, Ni: 25-60%,
Contains Cr: 22.5 to 30%, Mo: less than 8% and W: less than 16%, and further contains rare earth elements: 0.10% or less, Y: 0.20%. Ti or less, amount, fg: 0.10% or less, Ti: 0.5
% or less, Oh! Cr (%) + l OMo (f;) + 5 W S
)≧S○chi. 4%≦Mo(%i)++W(%)<8%. An alloy that satisfies the conditions of 2601■C(4)+130
The lower limit temperature C) calculated at 0 and U6Mo(A)+1o
After solid solution treatment at a temperature of 2 hours or less at a temperature between w (a) + 10 Cr (%) + upper limit temperature elongation calculated by 777), cold working is performed at a wall thickness reduction rate of 10 to 60%. A method for manufacturing high-strength oil country tubular goods with excellent stress corrosion cracking resistance. (4) C: 0.05% or less, 3i: 1.0%
Below, Mn: 2.0% or less, p Ho, 030% or less,
S: 0.005% or less %ot, AQ: 0.
5% or less, Ni: 25-60%, cr: 22.5-3
0%, contains one or two of Mo: less than 8% and W: less than 16%, and further contains one or two of Cu: 2% or less and CO: 2% or less. , rare earth elements: 0.10% or less. Y: 0.20% or less, Mg: 0.10% or less, '
l'i: 0.5- or less, and Ca: 0.10%
Contains one or more of the following, with the remainder consisting of Fe and unavoidable impurities (with a weight percent of Cr(@+10 MO(%)+5 W
(@≧70%. 4%≦MO (%) + + W (%) < 8%
. An alloy that satisfies the conditions of 260°C (%) +130
The lower limit temperature C) calculated at 0 and 16Mo(＼+1ow
After solution treatment at a temperature of 2 hours or less at a temperature between (@+10Cr (upper limit temperature calculated by @+'i"i") A method for producing high-strength oil country tubular goods with excellent stress corrosion cracking resistance, characterized by processing. (5) c: 0.05% or less, Si: 1.0
% or less, Mn: 2.0% or less, p: 0.030%
Below, S: 0.005% or less, soL, AQ:
0.5% or less, N: 0.05-0.3%. ) Contains Jl: 25-60%, Cr: 22.5-30%, Mo: less than 8% and W: less than 16%.
It has a composition (weight %) containing one or two species, and the rest consisting of Fe and unavoidable impurities, and Cr (%9+).
10M0 (n+5 W (%) 270%. 4chi≦Mo dull) 10+W (chi) <8%. An alloy that satisfies the conditions of 26010gC (to) + 13
00) and 16Mo (rigidity +10
．． After solution treatment at a temperature of 2 hours or less at a temperature between +100r (upper limit temperature calculated by @+77'7), cold working at a wall thickness reduction rate of 10 to 60 inches. A method for manufacturing high-strength oil country tubular goods with excellent stress corrosion cracking resistance. (6) c: o, o s4 or less, Si: l
, 04 or less, Mn: lower, sot, AM: 0.5
% or less, N: 0.05-0.3%. Contains Nl: 25-60%, Cr: 22.5-30%, 5-Mo: less than 8% and W: less than 16%, and further contains c... 2% or less and Co
:Contains one or two of the following: 2 or less, and the remainder is F.
having a composition (more than % by weight) consisting of e and unavoidable impurities,
And, 2601ogC (tlA+1
The lower limit temperature (C) calculated by 300 and 16Mo (Ki+
10W (9)) + 10Cr (5) to the upper limit temperature calculated by A method for manufacturing high-strength oil country tubular goods with excellent stress corrosion cracking resistance. ('i') C: 0.05% or less, Si: 1.0%
Below, Mn: 2.0% or less, P: 0.030% or less,
S: 0.005% or less, sol, AQ: 0.5% or less, N: 0.05-0.3%. Ni: 25-60%, Cr: 22.5-30%
Contains one or two of Mo: less than 8% and W: less than 16%, and rare earth element: 0.1
06- or less, Y: 0.20- or less, Mg: 0.10% or less. Contains one or more of Ti: 0.5% or less and Ca: 0.10% or less, and has a composition (weight % above) with the remainder consisting of Fe and unavoidable impurities. , Cr(@ + 10Mo (@ + 5 W (@≧7
o%. An alloy that satisfies the condition of 4%≦Mo(plow++W(4)<8%.2604C(%)+1300
The lower limit temperature (g) calculated by 16Mo (rust + 1o
After solution treatment at a temperature between the upper limit temperature (g) calculated by W(4)+10 Cr(@-)-77'7 and held for 2 hours or less, the wall thickness decreases by 10-60%. A method for producing high-strength oil country tubular goods with excellent stress corrosion cracking resistance, which is characterized by cold working at a low temperature. (8) C: O, 015% or less, Si: 1.0
96 or less, Mn: 2°0 or less, P: 0.03
0% or less, S: 0.005% or less, sot, AI
: 0.5 inch or less, N: 0.05 to 0.3%. Ni: 25-60%, Cr: 22.5-30%
, contains one or two of Mo: less than 84 and W: less than 16%, and further contains one or two of Cu: ``2''% or less and Co: 2% or less, Rare earth elements: 0.10% or less, Y: 0.20% or less, Muba: 0.10% or less, Ti: 0.5% or less, and Ca
: Contains one or more of C1. (@≧70chi.4chi≦Mo(@++W(%)〈8chi.2601ogCC%)-1-
The lower limit temperature (c) calculated at 1300 and 16Mo (%
)+10 W (%)+10cr (@10″/77) After solution treatment at a temperature between the upper limit temperature (g) calculated by 77 for 2 hours or less, the wall thickness decreases by 1.10 to 60%. A method for producing high-strength oil country tubular goods with excellent stress corrosion cracking resistance, which is characterized by cold working at a low temperature.