JPS589922A - 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, 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, 35-60% Ni, 22.5-35% Cr, <4% Mo, and/or <8% W, or further <=2% Cu, and/or <=2% Co, and the balance Fe in addition to these and satisfying Cr(%)+10Mo(%)+5W(%)>=50%, 1.5%<=Mo(%)+1/2W(%)<4% 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, with depths of 6000 m or more,
Some 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 Steer X steel 1riU, Incoloy, and Hastelloy (all trade names) for the production of oil country tubular goods, but so far, Regarding these alloys, the details of the corrosion behavior of H, s-co, and '-ct- in an oil well environment have not yet been fully elucidated, and it is difficult to understand whether they have the high strength required for oil country tubular goods for deep wells. The current situation is that it is not a thing.

Therefore, from the above-mentioned viewpoint, the present inventors have developed a material with high strength and excellent durability that can withstand oil drilling in deep wells and severe corrosive environments, especially in H2S-Co2-Ct- oil well environments. As a result of research to manufacture oil country tubular goods with stress corrosion cracking resistance, we found that (a) Stress corrosion cracking is the main cause of corrosion in the H2S-C02-CL environment, and the mode of stress corrosion cracking in this case is The behavior is completely different from that of typical austenitic stainless steels. That is, whereas general stress corrosion cracking is deeply related to the presence of ct-, in the oil well environment mentioned above, the influence of H2S is greater than that of Ct-.

(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.

(C) The elution rate (corrosion rate) of steel in an H2S-CO2-C1- environment depends on the content of Or, Ni, Mo, and W, and corrosion resistance is maintained by the surface film made of these components. In addition, these components also increase the resistance to stress corrosion cracking, and in particular, MO
MO is 10 times more effective than W, and MO is twice as effective as W. Therefore, this MO and W are 10 times more effective than Cr(+10 Mo(@+5 w(%)250%).

1.5%≦MO(%　10’r　W　(＠＜　4　%　.

If the following conditional expressions are satisfied, and the N1 content is 35 to 60% and the CR content is 22.5 to 35%, H2S-Co2-C, which is extremely corrosive, even if it is a cold-worked material.
It is possible to obtain a surface coating that exhibits excellent resistance to stress corrosion cracking under a t-oil well environment, particularly in a harsh environment of 150° C. or lower.

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

(e) When N is included as an alloy component in the range of 0.05 to 0.3%, the strength is further improved.

(f) S content as an unavoidable impurity is O, O'O
When O is reduced to 7 or less, the hot workability of the alloy is significantly improved.

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

(b) Corrosion resistance is further improved by containing 2% or less of Cu as an alloy component.

(i) Rare earth element as an alloy component: 0.10
% or less, Y: 0°20% or less, Mg: 0.10% or less, T1: 0.5% or less, and Ca: 0.10% or less. The machinability will be further improved.

(J) However, in order to ensure the desired high strength, the alloy with the above composition must be prepared using the empirical formula: 26010gC(%)-1-
1300 (lower limit temperature ℃) and the same empirical formula:
The carbide is completely dissolved in the alloy by heat treatment at a temperature of 2 hours or less at a temperature between 16% and 10%.
It is necessary to perform cold working with a wall thickness reduction rate of ~60 inches.

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, Si: 1.
0% or less, Mn: 2.0% or less, P: 0.03
0% or less.

Preferably, P:0 for the purpose of further improving hydrogen cracking resistance.
．． S: 0.003% or less, S: 0.005% or less, preferably S: O, OO for the purpose of further improving hot workability.
O'7 or less, sot, AA: 0.5% or less, N
i: 35-60%.

cr: 22.5 to 35%, contains one or two of Mo: less than 4% and W: less than 8%, and if necessary, N: 0.05 to 0.3. %,
Cu: 2% or less, Co': 2% or less, rare earth element: O,
10% or less, Y: 0.20% or less, Mg: 0.10
% or less, Ti: 0.5% or less, and Ca: 0.10%
Contains one or more of the following, and the remainder is Fe.
It has a composition consisting of and unavoidable impurities (the above weight and the following all mean weight -), Cr (%)
-) 10 Mo (%) -4-5W (@≧50%
.

1.5%≦MO (Hook + W (%) <’%.

An alloy that satisfies the conditions of 26010gC(9))+1
Lower limit temperature (6) calculated at 300 and 16Mo1%)
-1-10W book) + 10Cr (A) + 777 After solution treatment under the condition of holding for 2 hours or less at a temperature between the upper limit temperature (6) calculated by This method is characterized by a method for manufacturing high-strength oil country tubular goods with excellent stress corrosion cracking resistance by performing preliminary processing.

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

A, Component composition (,), (: 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 means that after cold working, It works effectively to increase strength. Therefore, it is desirable that the C content be as low as possible, but if the C content exceeds 0.05%,
Since intergranular stress corrosion cracking is likely to occur, the upper limit was set at 0.05 inches.

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

(c) Mn The Mn component tends to have a deoxidizing effect like Sl, and since this component has little effect on stress corrosion cracking resistance, the upper limit value was set at a relatively high value of 2.0. Ta.

(a) p The P component as an unavoidable impurity has a content of 0.0
If it exceeds 30%, the effect of increasing stress corrosion cracking susceptibility appears, so it is necessary to set the upper limit to 0.030% to keep stress corrosion cracking susceptibility to a low level. Also, P
It has been found that as the content is reduced, the hydrogen cracking resistance rapidly improves after reaching 0.003 mm.From this point, 1. In particular, when excellent hydrogen cracking resistance is required, the P content is desirably 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 as 5% O, OO to prevent deterioration of hot workability. In this way, the S component has the effect of deteriorating hot workability when its content increases, but when its content is lowered to 0.000'7%, the hot workability deteriorates. If hot working under severe conditions is required, it is desirable to set the S content to 0.0007% or less.

(f) AA A2 is effective as a deoxidizing component like Si and Mn, and even if it is included up to 0.5% in AA content, it will not impair the characteristics of the pipe material. The content was determined to be sot, and the M content was set to be 0.5 inches or less.

Ni) The N1 component has the effect of improving the stress corrosion cracking resistance of pipe materials, but if its content is less than 35%, the desired excellent stress corrosion cracking resistance cannot be secured; Even if the content exceeds 10%, no further improvement in stress corrosion cracking resistance will be obtained, and the content was determined to be 35 to 60%, taking economic efficiency into account.

(h) Cr The Cr component is a component that significantly improves stress corrosion cracking resistance when coexisting with Ni, Mo 1 and W components, but even if its content is less than 22.5%, hot workability is poor. On the contrary, in order to ensure the desired stress corrosion cracking resistance, the content of M'o and W must be increased accordingly, which is economically disadvantageous. Therefore, the lower limit was set at 22.5%.

On the other hand, if the S content exceeds 35%, deterioration in hot workability cannot be avoided no matter how much the S content is reduced, so the upper limit was set at 35%.

(i), Mo and W As mentioned above, these components have an equal effect of improving stress corrosion cracking resistance when coexisting with N1 and Cr, but MO: 4% or more and W: H2S-C whose environmental temperature is 150℃ or less even if it contains 8% or more
In the corrosive environment of O2-CL-, no further improvement effect was observed, and in consideration of economic efficiency, the respective contents were changed to
o: less than 4%, W: less than 8%. Also, Mo and W
The reason for specifying the content of Mo(@++W(%)) is because W has an atomic weight of about twice that of MO, and in terms of effects, they are equal at about +, so this value is 1.5%
If the value is less than 150°C, the desired stress corrosion cracking resistance cannot be obtained, especially under the adverse environment mentioned above. It is not economical to include Mo(Ll
;) +4 W blunt) value was determined to be 1.5 to less than 4%.

(j) N Since the N component has the effect of improving strength through solid solution strengthening, it is included as necessary when particularly high strength is required, but if the content is less than 0.05%, the desired strength cannot be achieved. No improvement effect can be obtained, and on the other hand, if the content exceeds 0.3%, melting and ingot making become difficult, so the content was set at 0.05 to 0.3%.

(k) 'Cu and C.

These components have a uniform effect of improving the corrosion resistance of the pipe material, and CO also has a solid solution strengthening effect.
In particular, it is added as necessary when even better corrosion resistance is required, but if it exceeds 2%, hot workability tends to deteriorate. Since no further improvement effect could be obtained even with the addition of 2% Cu and 2% Co, respectively, the upper limits were set as 2% for Cu and 2% for Co.

(t) Rare earth elements, Y, Mg, Ti, and Ca These components have a uniform effect that further improves hot workability, so they are necessary when hot working is performed under severe conditions. Contained depending on rare earth elements:
0.10%, Y: 0.20%.

Mg: 0.10%, Tioo, 5%, and Ca:
Even if the content exceeds 0.10%, no improvement effect on hot workability is observed, and even a deterioration phenomenon appears, so the content of each rare earth element: 0.10%
Y: 0.20 or less'+ Mg: 0.10%
Below, Ti: 0.5% or less, and Ca: 0.10
% or less.

(ffl) Cr (%) +10 Mo (@+5
W (%;) Figure 1 shows the stress corrosion cracking resistance under severe corrosive environments.
It shows the relationship between W (%) and N1 (90).

That is, Cr, N1. Mo.

and Cr-Ni-Mo systems with various W contents.

Cr-Ni-W system, and Cr-Ni-Mo-W
The steel is melted, cast, forged, and hot rolled to produce plate thickness:
'7mm plate material, then this plate material, temperature: 100
After being held at 0°C for 30 minutes and subjected to Mizusaki solution treatment, cold working was applied at a processing rate of 22% for the purpose of improving strength. :2mmX
A test piece of width: 10 mm x length: 15 mm was cut out, and a tensile stress equivalent to the yield strength of the test piece SK0.2 mm was applied to this test piece using a 3-point support beam jig shown in Fig. 2. 10 atm H2S and 10 atm C0
20% NaC saturated with H2S and CO2
4 solution (temperature: 150° C.) for 1000 hours and a stress corrosion cracking test was conducted, 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(@ + 10 M
o(%) + 5 W ,
The ○ mark indicates no cracking, and the X mark indicates cracking. From the results shown in Figure 1, Cr(%)+1
It is clear that when the value of 0M0(→'-F5 W (%)) is less than 50% and the Ni content is less than 35%, the desired excellent stress corrosion cracking resistance cannot be obtained.

In addition, in the alloy of the present invention, B, F3n, pb; and Zn are each 0 as unavoidable impurities.
．． Even if the content is in the range of 1- or less, the properties of the alloy of the present invention will not be impaired in any way.

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 content of 10 alloy claws, but also by cold working after complete solution treatment of carbides. 21- In this case, complete solid solution of carbide is 2601■C6g
)+1300゛ lower limit temperature (@ and 16ix
o(chi)-1-1'OW book)+10Cr(%9+777
The upper limit temperature calculated in 11c) is measured by holding the temperature between the table for 2 hours or less, but the above lower limit temperature calculation formula: 2601■C (%) and upper limit temperature calculation formula: 16Mo (@ +10 W (%) +10 Cr (%)
+777 was determined empirically based on numerous test results, and below the above lower limit temperature, carbide cannot be completely dissolved in solid solution, and undissolved carbide remains. Stress corrosion cracking susceptibility increases, and on the other hand, if the solution treatment temperature exceeds the above-mentioned upper temperature,
If the holding time is longer than 2 hours, the crystal grains will become coarse and the desired high strength cannot be obtained in the subsequent cold working, so the solution treatment temperature and holding time should be adjusted accordingly. Established as 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 with the wall thickness reduction rate is less than 10 degrees, 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 become significant. It was established that

By applying the above component composition and manufacturing conditions, we can produce oil country tubular goods that have a 0.2% proof stress of 8 o kgf/, a high strength of 4 or more, and have excellent stress corrosion cracking resistance as well as ductility and toughness. can be manufactured.

Next, the method for producing oil country tubular goods according to the present invention will be specifically explained in comparison with Examples and Comparative Examples.

In each of the examples, a molten metal having the composition shown in Table 1 was heated in a conventional electric furnace and an Ar-oxygen decarburization furnace (AOD furnace) for the purpose of desulfurization and N addition, and further as necessary. After melting using an electroslag melting furnace (ESR furnace) for the purpose of dephosphorization, it was cast into an ingot with a diameter of 2,500 yen, and then hot forged at a temperature of 1,200°C to make the diameter = A billet of 150 mm diameter was formed, and in this case, for the purpose of evaluating hot workability, the billet was extruded to prevent cracks from occurring.A raw tube of diameter: 60 mm diameter x wall thickness: 4 mm was formed. Subsequently, the alloy tube material of the present invention was produced by solution treatment and cold working under the solution treatment conditions (cooling after treatment was water cooling in both cases) and wall thickness reduction rate shown in Table 1. 1-29° Comparative alloy tube material 1-8. and conventional alloy tube materials 1 to 4 were manufactured, respectively.

In addition, Comparative Alloy Tube Materials 1 to 8 have one of the content of any of the constituent components or the manufacturing conditions (indicated with an asterisk in Table 1). The pipe material 1 was manufactured under conditions outside the scope of the present invention, and all of the conventional alloy pipe materials have known compositions, and the pipe material 1 is specified in JIS-8 US 316 and JIS-8 US 316. is JIS-3US 310S, and the same 3 is Incoloy 8
00 and 4 have compositions corresponding to JIS and SUS 329Jl, respectively.

Next, the resulting alloy tube materials 1 to 29 of the present invention and comparative alloy tube materials 1 to 8. A test piece of length: 20 g was cut out from each of the conventional alloy tubes 1 to 4, and a portion corresponding to 60° was cut off along the length direction of the test piece. As shown in the front view, the bolt is passed through and tightened with a nut to apply a tensile stress equivalent to 0.2 inch proof stress to the outer surface of the tube, and the H2S partial pressure is set to 0 for the test piece S in this state. .H2S at 1 atm, 1 atm, and 20 atm - 10 atm Cog - 20% Na
A stress corrosion cracking test was conducted by immersing the test piece in a C4 solution (liquid temperature: 150°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 addition, in Table 2, ○
Each mark indicates that no cracking occurred, while the X mark indicates that cracking occurred.

From the results shown in Table 2, comparative alloy tube materials 1 to 8 have hot workability and stress corrosion cracking resistance of 2. In contrast, the alloy tube materials 1 to 29 of the present invention all have excellent hot workability and stress corrosion cracking resistance, and also have high Conventional alloy tube materials 1 to 4 have strength and good hot workability, but have relatively low strength and poor stress corrosion cracking resistance.
It is clear that it has even better characteristics when compared to - As mentioned above, the oil country tubular goods manufactured by the method of the present invention have particularly high strength and excellent stress corrosion cracking resistance, so that they can be used in oil and natural gas applications in harsh environments where these properties are required. It exhibits extremely excellent performance not only in mining, but also when used as geothermal well pipes.

[Brief explanation of the drawings] Figure 1 shows the stress corrosion cracking resistance of the alloy, N1 content and Cr (%) -) -10Mo (@+ 5 W (%)
FIGS. 2 and 3 are diagrams showing the stress corrosion cracking test for plate-shaped and tubular specimens, respectively. Cr (%) + IOMo (%) + 5W (%)) 1 Figure 2 $ 3 Continuation of Figure 1 Page 0 Author: Takeo Kudo 1-3 Nishinagasu Hondori, Amagasaki City 1-3 Nishinagasu Hondori, Amagasaki City Address: Sumitomo Metal Industries, Ltd. Central Technology Research Laboratory 0 Inventor: Daiji Moroishi 1-3 Nishinagasu Hondori, Amagasaki City Sumitomo Metal Industries, Ltd. Central Technology Research Laboratory

Claims (1)

[Claims] (1) C: 0.05% or less, Si: 1.0% or less, Mn: 20% or less, P: 0.030% or less, S:
Contains 0.005% or less, sot, AQ: 0.5% or less, Ni: 35-60%, Cr: 22.5-35%, Mo: less than 4% and W: less than 8%. It has a composition (more than % by weight) containing one or two species and the rest is Fe and unavoidable impurities, and cr(%9 + l oMo(@+5 W (%)≧
50 chi. 1.5%≦MO (%) + +W (%) <'%. An alloy that satisfies the conditions of 2601 (HlC (@-1-
The lower limit temperature (6) calculated at 1300 and 16M0 (%
) + l OW (%) + 10 cr (upper limit temperature calculated in (A) 10'777) after solution treatment under conditions of holding for 2 hours or less, with a wall thickness reduction rate of 10 to 60 qA. A method for manufacturing high-strength oil country tubular goods with excellent stress corrosion cracking resistance, which is characterized by cold working. (2) C: 0.05% or less, Si: 1.0% or less, klu: 2.0% or less, P: 0.030% or less, S: 0.005% or less, SOI, AL: O1
5 inches or less, Ni: 35-60%, cr: 22.
Contains 5 to 35%, contains one or two of Mo: less than 4% and W: less than 8%, further Cu: 2%
Contains one or two of the following and Co: 2% or less, with the remainder consisting of Fe and unavoidable impurities (weight %), and Cr (%) -) -10λ4o
(%) +5 W (%) 250%. An alloy that satisfies the condition of 1.5%≦Mo(@+ +w (%)<2%.
The lower limit temperature (g) calculated in 00 and 16Mo (@±I
OW←)+10Cr(%)-1-'i'7 After solution treatment at a temperature between A method for manufacturing high-strength oil country tubular goods with excellent stress corrosion cracking resistance, which is characterized by cold working at a decreasing rate. (3) C: 0.05% or less, Si: 1.0% or less, Mn: 2.0% or less, P: 0.030% or less, S lower + sot, AQ: 0.5% or less, Ni: 35-6
0%, cr: Contains 22.5 to 35 chi, M'o:'
lfi of less than 4% and W: less than 8%! or 2
Contains seeds and further contains rare earth elements: 0.10% or less, Y
: 0.20% or less, Mg: 0.10% or less, Ti:
Contains one or more of the following: 0.5% or less, Oyobi Ca: O, jO% or less, with the remainder consisting of Fe and unavoidable impurities (in weight percent), Ga, Cr (Q, + 10 Mo (%) + 5 W'
611) 250%. 1.5%≦MO(%)++W(%)<4%. An alloy that satisfies the conditions of 2604C(5)+1300
) and 1-6M0(%)+10
W (%) + 10Or (%l + 7 !7, After solution treatment at a temperature between the upper limit temperature (6) calculated in '7 and held for 2 hours or less, the 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, characterized by end-to-end processing. 2.0% or less, P: 0.030% or less, S: 0.
O05chi or less, sot, Ai: 0.5% or less,
Contains Ni: 35-60%, Cr: 22.5-35%, Mo: less than 4% and W: less than 8%.
Contains one or two species, rare earth element: 0.10% or less. Y2 0.20- or less, Mg: 0.10% or less, '
I'i: 0.5% or less, and Ca: 0.10% or less, and the remainder is Fe and unavoidable impurities (weight %), And, an alloy that satisfies the conditions of 1.5%≦Mo (Working + W (a) + 4%) is 26014C (%) + 130
The lower temperature calculated at 0 and 16Mo'(@+10
After solution treatment under conditions of holding for 2 hours or less at a temperature between the upper limit temperature (6) calculated in 10'77'I. A method for producing high-strength oil country tubular goods having excellent stress corrosion cracking resistance, characterized by cold working at a medium thickness reduction rate of 10 to 60 inches. (5) 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, Al: 0.5
% or less, N: 0.05-0.3%. Ni: 35-60%, Cr: 22.5-35%
It contains one or two of Mo: less than 4% and W: less than 8%, with the remainder consisting of Fe and unavoidable impurities (wt%), %)
+ 10 Mo (%) + 5 W (%) 250%. 1.5%≦MO('IF)+'z W (%)<
'%. An alloy that satisfies the conditions is 26010gC(a)+13
Lower limit temperature (6) calculated with 00 and 16Mo dull)
After solution treatment at a temperature between the upper limit temperature (6) calculated by +10 W (%) + 100 r (%) + 7'/7 and held for 2 hours or less, the wall thickness of lO ~ 60 cm A method for manufacturing oil country tubular goods with excellent strength and stress corrosion cracking resistance, which is characterized by cold working at a decreasing rate. (6) C: 0.05% or less, S 1.0% or less,
Mn:Nl: 35-60%, Cr222.5-3
5%, MO: less than 4% and W': 84
Cu:2
% or less and C0:2% or less. (%)2
50%. 1.5%≦MO (%) + + W (%) <'%
. The alloy that satisfies the conditions is 26010gC (%) + 13
00 T) and 16Mo (%)
+10 W (%) 10Cr (%) 10'7'7'/
Stress corrosion cracking resistance characterized by solution treatment at a temperature between the upper limit temperature C) calculated by C) for 2 hours or less, and then cold working at a wall thickness reduction rate of 10 to 60%. A manufacturing method for high-strength oil country tubular goods with excellent properties. (Mc: o, o51 or less, Si: 10% or less, M
n: 2.0 cm or less, P: 0.0309 J or less, S
: 0.005% or less, sot, Al 20, 5 or less, N: 0.05 to 0.3%. Contains Nl: 35-60%, Cr: 22.5-35%, Mo: less than 4% and w: less than 8%.
Contains one or more rare earth elements: 0.10
% or less, Y: 0.20% or less, Mg: 0.10%
Below, lf of Ti: 0.5% or less and Ca: 0.10% or less! or contains two or more types, and the remainder is R'
having a composition (more than % by weight) consisting of e and unavoidable impurities,
Gah, cr (fishing + l oMo (1 + 5 w (1≧50
blood. 1.5%≦MO(%)10-)W(%)<4%. An alloy that satisfies the conditions of 2604C (a) + 1300
Tcalculated lower limit temperature (6) and 16Mo(5)+l0
After solution treatment at a temperature between the upper limit temperature (g) calculated by W (%) + 10 Cr (capital) + 777 for 2 hours or less, 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. (8) C: 0.05% or less, Si: 1.0
% or less, Mn: 2.0% or less, P: 0.030% or less, S 20.005% or less r sot, M: 0.
5 tl! Hereinafter, N: 0.05-0.3%. Ni: 35-60%, Cr: 22.5-35%
Contains one or two of M, o: less than 4 and w: less than 8, and further Cu: 2% or less and C. : 2% or less of one or two types and rare earth elements: 0
．． 10 or less; y: o, mo or less, Mg: 0.1
0 Ti or less, Ti: 0.5% or less, and Ca: 0.1
0% or less, and the remainder is Fe and unavoidable impurities (weight%), and cr(@+10 Mo(@+5 W(%)) ≧50%
. An alloy that satisfies the condition of 1.5%≦Mo(@++W(working<4C) is 2601.0(→+1300
The lower limit temperature (C) calculated by 1 sMo(4+l
After solution treatment at a temperature between the upper limit temperature (6) calculated by OW (el) + 10Cr (qQ + "l'l'l") and held for 2 hours or less, the wall thickness decreased by 10 to 60 inches. 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.