JPS589924A - Manufacturing method for high-strength oil country tubular goods with excellent 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, Mo, W, 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, 30-60% Ni, 15-30% Cr, <=12% Mo, and/or <=24% W, or further <=2% Cu, and/or <=2% Co, and the balance Fe in addition to these satisfying Cr(%)+10Mo(%)+5W(%)>=110%, 8%<=Mo(%)+1/2W(%)<=12% 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 is 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, recently stainless steel, as well as Incoloy and Nosteroy (both trade names) have been used to manufacture oil country tubular goods.
Consideration has begun to be given to the use of high-grade corrosion-resistant high-alloy steels such as H,
The details of corrosion behavior at the oil well source 9- boundary of S-co, -"C1- have not yet been fully elucidated, and furthermore, it does not have the high strength required for oil country tubing for deep wells. is the current situation.

Therefore, from the above-mentioned viewpoint, the present inventors have developed a material with high strength and excellent stress corrosion resistance that can withstand oil drilling in deep wells and harsh corrosive environments, especially in H2S-Co2-01- oil well environments. As a result of research to manufacture oil country tubular goods with crackability, it was found that (a) The main cause of corrosion in the H2S-Co2-0L environment is stress corrosion cracking, and the mode of stress corrosion cracking in this case is as follows: The behavior is completely different from that of general austenitic stainless steel. That is, while general stress corrosion cracking is deeply related to the presence of at-, in the oil well environment mentioned above, the influence of H2S is greater than that of at-.

(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.

110- (c) The elution rate (corrosion rate) of steel in an H2S -002-at- environment depends on the content of Or, Ni + Mo + and W, and corrosion resistance is maintained by the surface film made of these components. , and these components also increase its resistance to stress corrosion cracking, and in particular, Mo has a 1% resistance to Or.
0 times the effect, and Mo has twice the effect of W. Therefore, this Mo and W are Or (@ +1
0 Mo (%) +5 W (%) 2110%.

8%≦MO(a)10-W(@≦12%.

Satisfy the conditional expression and reduce the N1 content to 30 to 60%.
, when the Or content is 15 to 30%, H2S-C02-at- is extremely corrosive even when cold-worked.
It is possible to obtain a surface coating that exhibits excellent resistance to stress corrosion cracking under an oil well environment, particularly in a harsh environment of 200°C or higher.

(d) Ni 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 a latitude range of 0.05 to 3 qb, the strength of the pipe material is further improved.

(f) S content as an unavoidable impurity is set to 0.000
If it is reduced to less than 'i', the hot workability of the tube material will be significantly improved.

←) When the P content as an unavoidable impurity is reduced to 0.003 h or less, the hydrogen cracking susceptibility is significantly reduced.

(h) Cu: 2% or less and Co: as alloy components
Corrosion resistance can be further improved by containing one or two of the following.

(1) Rare earth elements as alloy components: o, lo% or less,
Y: 0.20% or less, Mg: 0.10% or less, T
When one or more of Ca: 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 prepared using the empirical formula: 2601ogC(A)+130
0) and the same empirical formula -16
M0(%;)+l o'w(4+10 Or($) +
2 for the temperature between the upper limit temperature (℃) calculated in '7'77
It is necessary to completely dissolve the carbide by heat treatment under conditions of holding for less than 1 hour, and then cold work the alloy after solid solution at a wall thickness reduction rate of 10 to 60%.

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

Therefore, this invention was made based on the above knowledge, and C: 0.05% or less, S1: 1.0%.
Less than or equal to 1, Mn: 2.0% or less, P: 0.030%
Hereinafter, for the purpose of further improving hydrogen cracking resistance, P: 0.003% or less, S: 0.005% or less.

Preferably, S20 is added for the purpose of further improving hot workability.
Contains 0O07% or less, sot, Ag,: 0.5% or less, N1: 30-60%, Or: 15-30%,
Contains one or two of MO: 1z% or less and W: 24% or less, and if necessary, N: 0.05
~0.3%, Cu: 2% or less, Co: 2% or less.

Rare earth elements: O, 10% or less, Y: 0.20% or less.

A composition containing one or more of Mg: 0.10% or less, Ti: 0.5% or less, and Ca: 0.10% or less, with the remainder consisting of Fe and inevitable impurities (hereinafter referred to as % by weight, all indications below - mean % by weight) 1
3- and Or(%+10Mo@+5W(II)2110%.

8chi≦Mo (%) + -W (d≦12chi.

An alloy that satisfies the conditions of 2601ogc (%) +
The lower limit temperature (℃) calculated at 1300 and 16Mo (4
)+l0W(a)+10Or(a)+777 After solution treatment at a temperature between the upper limit temperature (℃) calculated by 777 for 2 hours or less, cold treatment at a wall thickness reduction rate of lO~60cm. This method is characterized by a method of manufacturing high-strength oil country tubular goods with excellent stress corrosion cracking resistance through 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 to the above-mentioned values will be explained below.

A. Component composition (a) The lower the O 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 improve the strength after cold working. 14- It works more effectively by rising. Therefore, C
It is desirable that the content be as low as possible, but if the C content is
If the content exceeds 5%, intergranular stress corrosion cracking tends 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%. It's a rule.

(c) Mn The Mn component has a deoxidizing effect similar to Sl, and since this component has almost no effect on stress corrosion cracking resistance, the upper limit value was set at a higher value of 2. It was set as Q%.

(d) 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 and cracking will appear, so the upper limit value is set at 0.030・chi, and the stress corrosion cracking susceptibility will suddenly increase after 0.003%, which is a low state. It has been found that hydrogen cracking resistance is improved, and from this point of view, when particularly excellent hydrogen cracking resistance is required, it is recommended to set the P content to 0.0030% or less. desirable.

(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 when its content is lowered to 0.0007%, hot workability improves even further. Therefore, when hot working under severe conditions is required, it is desirable that the S content be 7% or less.

(f) he.

AA is effective as a deoxidizing component like Sl and Mn, and it does not impair the properties of the pipe material even if it is contained up to 0.5% in terms of reed, soL, and Al contents. Shima et al. , the Al content was set at 0.591 or less.

(C) Nl The N1 component has the effect of improving the stress corrosion cracking resistance of the tube sheet, but if its content is less than 30 g, it is impossible to secure the desired excellent stress corrosion cracking resistance; 60
Even if the content exceeds 10%, no further improvement in stress corrosion cracking resistance will be obtained, and the content was set at 30% to 60% in consideration of economic efficiency.

(h) It is a component that significantly improves stress corrosion cracking resistance in coexistence with the 0r Or acid component, Ni + Mo + and W components,
Even if the content is less than 15%, hot workability will not be improved; on the contrary, in order to secure the desired stress corrosion cracking resistance, the content of Mo and W must be increased to that extent. Since this would be economically disadvantageous, the lower limit was set at 15%. On the other hand, if the S content exceeds 30%, no matter how much the S content is reduced, deterioration in hot workability cannot be avoided, so the upper limit was set at 30%.

(i) Mo and W As mentioned above, these components have an equal effect of improving stress corrosion cracking resistance when coexisting with N1 and Or, but Mo: 12% and W: 24%, respectively. H2S at an environmental temperature of 200°C or higher even if the content exceeds
-co2- ct'- (7) In a corrosive environment, no further improvement effect appeared, and in consideration of economic efficiency, the respective contents were determined to be Mo: 12'1 or less and W: 24% or less. . In addition, regarding the content of MO and W, the conditional expression: MO Therefore, if this value is less than 8%, the desired stress corrosion cracking resistance cannot be obtained, especially in the above-mentioned adverse environment of 200 ° C. or higher, but on the other hand, even if this value is increased to more than 12%, As mentioned above, it contains substantially unnecessary amounts of Mo and W, which is not economical, and from this point of view, the value of Mo (a) + - W (a) is set to 8 to 12%.
It was determined that

18- Since it would be difficult, the content was set at 0.05 to 0.3 chi.

(k) Cu and C.

These components tend to have a uniform effect on improving the corrosion resistance of the pipe material, and CO also has a solid solution strengthening effect.
In particular, it is included as needed when even better corrosion resistance is required, but if CU exceeds 2%, hot workability will deteriorate, while c'o exceeds 2%. Even if they were included, no further improvement effect would appear, so the upper limits were set at 2 for Cu and 2 for Co, respectively.

(1) Rare earth elements, Y, Mg, Ti, and Ca These components have a uniform effect of improving hot workability to a large extent, so they are necessary when hot working is performed under severe conditions. Rare earth elements: 0.10%, Y: 0.20%, respectively.

Even if the content exceeds Mg: 0.10%, Ti: 0.5%, O and Ca: 0.10%, no improvement effect is seen on hot workability, and rather a deterioration phenomenon appears. Therefore, the content of each rare earth element:
0.10% or less, Y: 0.20 or less, Mg: 0.
10% or less, Ti: 0.5% or less, and (:a:
O, 10% or less.

(m) cr(@+10Mo(@+5w)(@Figure 1 shows stress corrosion cracking resistance under severe corrosive environment.
Cr (9gl+ 10Mo (proboscis + 5 W (@ and N
i (indicates the relationship with emotion, i.e. Cr
, Ni, Mo.

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

Cr-Ni-W and Cr-Ni-Mo-W steels are melted, cast, forged, and hot-rolled into a sheet material with a near thickness, and then this sheet material is heated at a temperature of: After holding the temperature at 100℃ for 30 minutes and applying water-cooling solution treatment, cold working was applied at a working rate of 22% for the purpose of improving strength. : 2 spaces x width: 1
A test piece with a length of 0 m11 x near 5 m11 L was cut out, and a tensile stress equivalent to 0.2 inch proof stress was applied to the test piece S using the three-point support beam jig shown in Fig. 2. 20% NaC saturated with H2S and CO2 with 10 atm H2S and 10 atm CO2
1 solution (temperature: 150° 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(@+10Mo(%
) + 5 w indicates no cracking and X indicates cracking.From the results shown in Figure 1, Cr(%)+10Mo(
919'+5 W (%) value is less than 50%,
It is clear that if the Ni content is less than 35%, the desired excellent stress corrosion cracking resistance cannot be obtained.

In addition, in the alloy of this invention, 1 is an unavoidable impurity.
3, 0.1% each of Sn, Pb, and Zn
Even if it is contained within the following range, 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 ensured not only by the inclusion of alloy components but also by cold working after completely solid solutionizing the carbides. It is 21-years old. In this case, the complete solid solution of carbides is 2 e olog
c S) + 1300 calculated lower limit temperature (@ and 16
Mo (%) + 1 OW (%) + 10 Cr (% + 7'C) By keeping the temperature between the calculated upper limit temperature ('C) for 2 hours or less, the name is calculated as the lower limit temperature above. Formula: 2 a Calculation formula for OlogC (%) and upper limit temperature: l 6Mo (rust + OW (%) 10: c
o cr (%) +7 '7 'i' was determined empirically based on the results of numerous tests, and below the above lower limit temperature, carbides cannot be completely dissolved and remain unsolidified. The susceptibility to stress corrosion cracking increases as carbides in the solution remain, and on the other hand, if the solution treatment temperature exceeds the above upper limit temperature or the holding time exceeds 2 hours, Since the crystal grains become coarse and the desired high strength cannot be obtained in the subsequent cold working, 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, when the wall thickness decreases22-, the crystal grains become coarser and the desired high strength cannot be obtained in subsequent cold working.
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 reduces the wall thickness by less than 10%, the desired strength cannot be secured. On the other hand, cold working with a wall thickness reduction rate of more than 60% causes significant deterioration of ductility and toughness, so cold working was set at a wall thickness reduction rate of 10 to 60%.

By applying the above component composition and manufacturing conditions, it has a high strength of 0.2 inch yield strength of 85 to 91'/- or more,
Moreover, oil country tubular goods having 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 using examples and comparing with comparative examples.

In each of the examples, a molten Ar-oxygen decarburization furnace (AOD furnace) having the composition shown in Table 1 was used, and if necessary, an electroslag melting furnace (ESR furnace) was used for the purpose of dephosphorization. After melting, it is cast into an ingot with a diameter of 500 mm, and then this ingot is hot forged at a temperature of 1200 °C to form a billet with a diameter of 150 m + 1 mm, and in this case, hot workability is evaluated. The billet was then inspected for cracks, and then subjected to multi-hot extrusion to a diameter of 60mm. mφ x wall thickness: 4 pieces of raw pipe are molded, and then solidified with the solid solution conductivity (cooling chip Jl of processing flt f& is also water-cooled) and wall thickness reduction rate shown in Table 1. By performing solution treatment and cold working, the alloy tube materials 1 to 29° of the present invention and the comparison alloy tube materials 1 to 8. and conventional alloy tube materials 1 to 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 in accordance with JIS-8US 316, and the same 2 is in accordance with JIS-8US 316.
'S-SUS 310S, the same 3 is Incoloy 800
In addition, No. 4 has a composition corresponding to JIS and -8US 329 Jl, respectively.

Next, the resulting alloy tube materials 1 to 29 of the present invention and comparative alloy tube materials 1 to 8. Then, a test piece with a length of 20 mm was cut out from each of the conventional alloy tube materials 1 to 4, and a portion corresponding to 60° was cut off along the length direction of this test piece. As shown in the front view in the figure, a bolt is passed through and tightened with a nut to apply a tensile stress equivalent to 0.2% yield strength to the outer surface of the tube, and the H2S partial pressure is applied to the test piece S in this state. H2S - 10 atm (302 - 20% N
A stress corrosion cracking test was conducted by immersing the sample in an a1l solution (liquid temperature: 300° 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 25-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.
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 strength and good hot workability, but have relatively low strength. It is clear that this material has even better properties than conventional alloy tube materials 1 to 4, which have low stress corrosion cracking resistance and are inferior in stress corrosion cracking resistance.

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, and therefore can be used in oil and natural gas under 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 drawing]

Figure 1 shows the stress corrosion cracking resistance of the alloy, with Ni content and Or 1%) + l OMo (@ + 5 W@
FIGS. 2 and 3 are diagrams showing the stress corrosion cracking test for plate-shaped and tubular specimens, respectively. Applicant Sumitomo Metal Industries Co., Ltd. Agent Tomi 1) Kazuo Figure 1 Cr(%-f 10Mo(%)-5W(%n Continued from page 1) 0 Inventor Takeo Kudo 1 Nishinagasu Hondori, Amagasaki City Chome 3, Central Technology Research Laboratory, Sumitomo Metal Industries, Ltd. 0 Author: Akio Ikeda, Amagasaki City, Nishinagasu Hondori, 1-3, Sumitomo Metal Industries, Ltd. Central Technology Research Laboratory, Chome

Claims (8)

[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* 5oLA1:
0.5% or less, Ni: 30-60%. Contains 15 to 30% of Cr, one or two of Mo: 12% or less and W: 24% or less, with the remainder consisting of Fe and unavoidable impurities (wt%). , and Cr (%) + l OMo ($) −) −5W(
4≧llo%. 8%≦Mo @;) + −W ($)≦12chi. The alloy that satisfies the 0 condition is 2601ogC dull) + 1
The lower limit temperature (℃) calculated at 300 and 16-Mo Camphor +
After solidifying at a temperature between 1'eW ($) + 10 Or (%) + 777 upper limit temperature (°C)'-]- for 2 hours or less, 10 to 60% of the meat A method for producing high-strength oil country tubular goods with excellent stress corrosion cracking resistance, which is characterized by cold working at a rate of thickness reduction. (2) C: 0.05% or less, Si: 1.0
% or less, Mn: 2.0% or less, P: 0.030% or less I
S: 0.005% or less + sot, AQ: 0
．． 5% or less, N1: 30-60%. Contains Cr: 15 to 30%, contains one or two of Mo: 12% or less and W: 24% or less, and further contains one of Cu: 2% or less and Oo: 2% or less. containing one or two species, the remainder having a composition (weight %) consisting of Fe and unavoidable impurities, and Or (91il
+ 10 Mo (%) + 5 W ([5110%. 8% ≦ Mo (hook + - W (4) 512%. An alloy that satisfies the - condition of 2601ogC (@-) -
The lower limit temperature (C) calculated at '1300 and 16M0 (
4) After solution treatment at a temperature between the upper limit temperature (°C) calculated by +l0W(1)+10 Or(a)+777 and held for 2 hours or less, the wall thickness was reduced 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, which is characterized by cold working. (3) C: 0.051% or less, Si: 1.0% or less, Mn: 2.0% or less, P: 0.030% or less,
S: 0.005% or less + sot, A1: 0
．． 5% or less, Ni: 30~'60%, cr: 15~
30%, contains one or two of Mo: 12% or less and W: 24% or less, and further contains rare earth elements: O, 10% or less, Y: 0.20% or less + Mg:O
A composition containing one or more of -10'16 or less, Ti: 0.5% or less, and Ca: 0.10% or less, with the remainder consisting of Fe and unavoidable impurities (wt%) and Or(%)+10Mo(tl+5w(@≧1
10%. 8%≦MO(@+W(%)612%. 2601ogo(%)+
The lower limit temperature (C) calculated at 1300 and 16Mo@-
)-10W(1)+l OCr(4)+777 After solution treatment at a temperature between the upper limit temperature (C) calculated by 777 and held for 2 hours or less, the wall thickness was reduced by 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. (4) C: 0.05% or less, Si: 1.0 or less, MID: 2.0 or less, P: 0.030% or less, S
: 0.005% or less + sot, Ai: 0.5
Chi and below, Ni: 30-60 悌. Contains Cr: 15 to 30%, contains one or two of Mo: 12% or less and W: 24% or less, and further contains one of O: 2% or less and CO: 2% or less. Or 2 types, rare earth element: 0.10% or less, Y: 0.2
Contains one or more of the following: 0 coefficient or less, Mg: 0.10% or less, T: 0.5% or less, and Ca: 0.10% or less, and the remainder consists of Fe and inevitable impurities. has the composition (more than % by weight), and Or(%)+
10Mo(%9 +5W(%D≧110%. 81%≦MO(a)+TW(4)≦12chi.) An alloy that satisfies the conditions of 2601ogC(a)+13
The lower limit temperature (℃) calculated from 00 and 16Mo(4)+
After solution treatment at a temperature between the upper limit temperature (C) calculated by 10W (long + 1Ocr (4) + 777) for 2 hours or less, cold working at a wall thickness reduction rate of 10 to 66%.
□A method for producing high-strength oil country tubular goods with excellent stress corrosion cracking resistance. (5) 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 + sot, Al: 0.5
% or less, N: 0.05-0.3%. Contains Ni: 30-60%, Or: l 5-30%, Mo: 12% or less and W: 24% or less.
The lower limit temperature (°C) calculated by 2601ogO (a) + 1300 is an alloy that has a composition (by weight %) containing one or two species and the remainder consisting of Fe and unavoidable impurities, and that satisfies the following conditions: and 16M0(1)+1OW(@-1
Upper limit temperature (℃) calculated by -1ocr(a)+777
High-strength oil country tubular goods with excellent stress corrosion cracking resistance, characterized by being subjected to solid solution treatment at a temperature between manufacturing method. (6) C: 0.05% or less, Si: 1.0%
Below, Mn: 2.0% or less, P: 0.030% or less, S: 0. <) 05% or less + 5oLA1:
0.5% or less, N: 0.05-0.3%, N: 30
Contains ~60% + Cr:'15-30%, Mo:
Contains one or two of the following: 125% or less and W: 24% or less, and further contains Cu: 2% or less and Co: 2% or less.
Contains one or two of the following, with the remainder consisting of Fe and unavoidable impurities (weight%), and Or (Work + l OMo% + 5 W (n≧110%)
. 8%≦Mo(d+−W(4)612%.) An alloy satisfying the condition of 2601ogC(a)+13
The lower limit temperature (℃) calculated at 00 and 16M0 (a) +
After solution treatment at a temperature between the upper limit temperature (℃) calculated by 10W (4) + 10Cjr (a) + 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. (7) c: o, o5q6 or less, Si: 1.0% or less, Mn: 2.0% or less, P: 0.030% or less, S:
0.005% or less + soL/u: 0.5 inches or less, N: 0.05 to 0-13 inches. Contains Ni: 30-60%, Or: 15-30%,
Contains one or two of Mo: 12% or less and W: 24% or less, and further contains a rare earth element: O,'10=
6-chi or less, Y: 0.20% or less, Mg: O, l 0%
below. T]: 0.5% or less, and Ca: 0.10'16
Contains one or more of the following, with the remainder being Fe
and unavoidable impurities (weight %), 1 force, Or (%) + l OMo (%) + 5W (%) ≧ 110'
%. 8%≦MO(a)+, w(a)≦12chi. An alloy that satisfies the conditions of 2601ogC(a)+13
The lower limit temperature (C) calculated at 00 and 16M0 (a) +
After solution treatment at a temperature between the upper limit temperature (°C) calculated by 10W (a) + 1OCr (a) + 777 for 2 hours or less, cold working at a wall thickness reduction rate of 10 to 60es. 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: z, oelb or less, P: 0.030 chi or less, S: 0. O05chi or less, sot, A1: 0
．． 5% or less, N: 0.05-0.3% + Ni: 30
~60%, Or: 15. -30%, Mo
: 12% or less and W: 24% or less, further Cu: 2% or less and CO: 2%
One or two of the following and rare earth elements: O, lO
Chi or less, Y: 0.20 or less. A composition containing one or more of Mg: 0.10% or less, Ti: 0.5% or less, and Ca: 0.10% or less, with the remainder consisting of Fe and inevitable impurities (
or more weight%), and Cr (%) + 10 Mo (%) + 5W (%) ≧ 11
0%. The alloy that satisfies the condition of 8chi≦Mo (慟十CHOW(4)≦12chi.) is 2601ogc (%) +
The lower limit temperature (℃) calculated at 1300 and 16Mo (4
)+10W (upper limit temperature CC calculated by +10 cr@-1-77'/) After solution treatment at a temperature of 2 hours or less, cooling with a wall thickness reduction rate of 10 to 60%. A method for producing high-strength oil country tubular goods with excellent stress corrosion cracking resistance, which involves special processing.