590mpa grade h2s stress corrosion resistant electric resistance welded oil casing and method of manufacturing the same

Abstract

The present application relates to the technical field of resistance welded oil casing production, and particularly relates to a 590MPa grade H2S stress corrosion resistant resistance welded oil casing and a manufacturing method thereof.C: 0.11%-0.14%, Si: 0.15%-0.30%, Mn: 0.80%-1.20%, P: <=0.015%, S: <=0.004%, Ti: 0.01%-0.03%, Cr: 0.10%-0.30%, V: 0.03%-0.06%, Mg: 0.004%-0.006%, Zr: 0.0006%-0.003%, Als: 0.02%-0.05%, N: <=0.008%, and the rest is Fe and inevitable elements.A low-carbon Cr-V composite design containing magnesium is adopted, the material has high strength after heat treatment, better low-temperature toughness, and excellent SSC resistance; Mg can refine inclusions, effectively change the morphology and size of inclusions, and is beneficial to SSC performance and impact; Cr and V can effectively improve the strength and SSC resistance; Pcm is lower than 0.23%, and the weldability is good; the whole pipe is subjected to quenching and tempering heat treatment, and the final organization is tempering sorbite, thereby ensuring the consistency of the pipe body and the weld performance. The brittle fracture of the oil well pipe can be prevented, the safety is higher, and the alloy cost is moderate.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of resistance welded oil casing production, and particularly relates to a 590MPa grade H2S stress corrosion resistant resistance welded oil casing and a manufacturing method thereof. BACKGROUND

[0002] Oil casing is one of the most commonly used oil special pipes in oil fields, and has the highest cost proportion. The HFW (high frequency welded) casing has the advantages of uniform wall thickness, high dimensional accuracy, good perforation performance, strong anti-collapse capacity and low cost compared with seamless pipes, and is gradually replacing traditional seamless steel pipes.

[0003] With the increasing demand for world energy and the increasing production of oil and gas, the corrosion and protection of oil casing have gradually become the focus of attention. H2S corrosion of oil casing has become the main corrosion type faced by oil and gas fields, which has caused huge economic losses to oil fields. Therefore, it is of great social and economic significance to develop oil casing with good corrosion resistance.

[0004] The tensile strength of the 590MPa grade is M65 steel grade specified in API Spec 5CT. API Spec 5CT specifies that the yield strength of M65 grade is between 448-586MPa, the tensile strength is greater than or equal to 586MPa, the elongation is greater than or equal to 22%, the transverse Charpy impact energy at 0℃ is greater than or equal to 20J, and the H2S stress corrosion resistance SSC is loaded with 72% nominal yield strength according to NACE TM0177 method A solution for 720 hours without cracking. In order to ensure the resistance welded M65 straight welded oil casing, good welding performance is required, and the cold crack sensitivity coefficient Pcm is as low as possible; in order to ensure the impact resistance and extrusion, a certain impact toughness is required; in order to ensure the HIC resistance, the inclusions and the fine and uniform structure need to be controlled; in order to ensure the strength, a certain amount of alloy is added to refine the grain and provide quenching property.

[0005] Chinese patent document CN104357756A discloses "a kind of anti hydrogen sulfide stress corrosion straight weld oil casing and its manufacturing method". The composition contains C: 0.08%-0.15%, Si: 0.15%-0.30%, Mn: 0.50%-1.00%, P≤0.010%, S≤0.0050%, Cr: 0.40%-0.65%, Ni≤0.25%, Mo: 0.30%-0.50%, Nb≤0.02%, V: 0.05%-0.10%, Zr: 0.0005%-0.01%, Al: 0.005%-0.01%, Ca: 0.001%-0.003%, B: 0.0005%-0.001%, RE: 0.001%-0.005%. The steel grade is 90 ksi, i.e. C90 of API standard, using production of secondary refining, RH furnace vacuum treatment and continuous casting, and being hot mechanically rolled into plate coil by continuous rolling mill production line, and being HFW pipe, and being high temperature tempered and stress relieved to obtain qualified steel pipe. However, due to low C and Mn content, high strength requirement, a large amount of valuable alloy elements Mo, Ni, V, Nb, etc. must be added, and the alloy cost is high; and the smelting process is complex due to the addition of Zr, Ca, B and RE.

[0006] Chinese patent document CN102296233A discloses "steel for high frequency resistance welded oil casing and its manufacturing method". The composition contains C: 0.15%-0.35%, Si: 0.10%-0.60%, Mn: 0.30%-1.00%, P≤0.015%, S≤0.003%, Mo: 0.1%-0.5%, V: 0.03%-0.20%, Nb: 0.01%-0.05%, Ti: 0.01%-0.05%, Al: 0.01%-0.08%, Ca: 0.001%-0.005%, B: 0.001%-0.003%. The steel grade is 80 ksi, i.e. N80 of API standard, the product uses production of secondary refining, RH furnace vacuum treatment and continuous casting, and is hot mechanically rolled into plate coil by continuous rolling mill production line, and is HFW pipe and on-line weld normalizing treatment to obtain qualified steel pipe. However, the C content is high, the HFW weldability is poor, and the SSC performance is not good; the valuable element content of Mo, V, Nb and Ti is high, and the alloy cost is high.

[0007] In summary, the 590 MPa grade resistance welded oil casing at present stage has the following defects: insufficient SSC performance, low strength after material heat treatment, insufficient low temperature toughness, brittle fracture of oil well pipe, poor safety, and high alloy cost. SUMMARY

[0008] In order to overcome the prior art, the present application provides a 590MPa grade H2S stress corrosion resistance resistance welding oil casing and a manufacturing method thereof. The material has high strength after heat treatment, better low temperature toughness, excellent SSC resistance, can prevent brittle fracture of oil well pipe, has higher safety, and the alloy cost is moderate.

[0009] In order to achieve the above purpose, the present application adopts the following technical scheme:

[0010] A 590MPa grade H2S stress corrosion resistance resistance welding oil casing, the chemical composition is as follows in terms of weight percentage:

[0011] C: 0.11%-0.14%, Si: 0.15%-0.30%, Mn: 0.80%-1.20%, P: ≤0.015%, S: ≤0.004%, Ti: 0.01%-0.03%, Cr: 0.10%-0.30%, V: 0.03%-0.06%, Mg: 0.004%-0.006%, Zr: 0.0006%-0.003%, Als: 0.02%-0.05%, N: ≤0.008%, and the rest is Fe and inevitable elements.

[0012] The steel grade in API SPEC 5CT of the present application is M65, suitable for quenching and tempering state, and the impact energy at-20℃ is greater than 150J, the Pcm is lower than 0.23, and the high toughness resistance welding (HFW / ERW) oil casing has good weldability.

[0013] A manufacturing method of a 590MPa grade H2S stress corrosion resistance resistance welding oil casing, specifically comprising the following steps:

[0014] 1) Smelting continuous casting:

[0015] Hot metal pretreatment, converter smelting - through top blowing or top and bottom combined blowing, external refining, LF furnace light desulfurization treatment and calcium treatment to control inclusion morphology and improve the ductility, toughness and cold bending performance of the steel, and continuous casting slab is made into continuous casting slab - electromagnetic stirring or dynamic soft reduction is used in continuous casting to improve the quality of the continuous casting slab.

[0016] 2) Rolling:

[0017] The continuous casting slab is heated to 1100-1180℃ by a heating furnace, and then hot continuous rolling is adopted, and the finish rolling temperature is 750-820℃.

[0018] 3) Cooling:

[0019] The steel strip is cooled at a cooling speed of 16-21℃ / s after rolling.

[0020] 4) Coiling:

[0021] After cooling, coiling is carried out, and the coiling temperature is 540-590 DEG C. After hot rolling, the bainite structure of the plate coil is obtained, the yield strength is above 500 MPa, the tensile strength is above 590 MPa, and the impact energy at-20 DEG C is above 200 J.

[0022] 5) The steel strip is welded into a steel pipe through a HFW unit. The temperature range is beneficial to the uniformity and refinement of ferrite structure, and can avoid the generation of non-uniform structure to adversely affect the SSC performance.

[0023] 6) The pipe is subjected to a quenching and tempering heat treatment:

[0024] The pipe is heated to 850-890 DEG C, and held for 25-35 min, and then water quenched; and then the pipe is heated to 480-540 DEG C, held for 35-58 min, and then water cooled and tempered, and rapid cooling after tempering can effectively inhibit high-temperature tempering brittleness.

[0025] The final structure of the steel pipe is tempered sorbite; the Pcm is below 0.23%, the A / B / C / D inclusion level is below 1.0 grade, the value level of each type is below 1.5 grade, and the banded structure is below 0.5 grade.

[0026] Compared with the prior art, the present application has at least the following technical effects or advantages:

[0027] 1) In the present application, C: 0.11%-0.14% can ensure the strength and hardness of the material, and can ensure the strength, toughness, plasticity and weldability after heat treatment. Mg: 0.004%-0.006% can reduce the oxygen and sulfur content and the number of inclusions in the steel, purify the liquid steel, obviously change the inclusions in the steel, and improve the performance of the steel. Cr: 0.10%-0.30% can be uniformly distributed in the steel volume, and can play a role in refining the grains; chromium also has the effect of reducing the corrosion rate of the steel in a high-temperature carbon dioxide environment, slowing down the corrosion rate of the oil casing in the oil well, and improving the service life. V: 0.03%-0.06% can significantly improve the yield strength and tensile strength of the material, and can improve the low-temperature impact toughness; when melted into austenite at high temperature, the quenching property of the steel can be increased; and when dissolved in ferrite, the solid solution strengthening effect is extremely strong. In the quenching and tempering heat treatment process, the grain growth can be hindered, and the strength and toughness of the steel can be greatly improved whether quenching or tempering.

[0028] In the present application, low-carbon Cr-V composite design containing magnesium is adopted, the strength of the material after heat treatment is high, the low-temperature toughness is better, and the SSC performance is excellent.

[0029] 2, the application adds Mg to refine inclusions, can effectively change the morphology and size of inclusions, and the magnesium oxide is dispersed in the steel, forming inclusions, significantly improving corrosion resistance, improving SSC performance and impact resistance.

[0030] 3, the application Cr element is dissolved in austenite, which increases the stability of supercooled austenite, moves the C curve to the right, improves the hardenability of the steel, promotes the transformation of bainite, and makes the steel have high strength, hardness and wear resistance; improve the anti-SSC performance.

[0031] 4, the application Pcm is less than 0.23%, and the weldability is good. The existing M65 generally uses C content of 0.20% or more, Mn content of 1.0% or more, and Pcm close to 0.25%. When the Pcm value is greater than 0.25, the cold cracking tendency increases obviously, and the weldability decreases. The lower the Pcm is, the better the weldability is, and the weldability is excellent when it is less than 0.23%.

[0032] 5, the application V, Ti, the content of valuable elements is less, and the alloy cost is low.

[0033] 6, the application is rolled at a temperature of 540-590 DEG C, which is beneficial to the uniformity and refinement of ferrite structure, and avoids the adverse effects of uneven structure on SSC performance.

[0034] 7, the application is quenched and tempered, and the tempering is water cooled, which can effectively inhibit the high temperature tempering brittleness; the final structure is tempered sorbite, which ensures the consistency of the performance of the pipe body and the weld. DETAILED DESCRIPTION

[0035] The application discloses a 590MPa grade H2S stress corrosion resistant electric resistance welded oil casing pipe and a manufacturing method thereof. Those skilled in the art can refer to the content of the present application and appropriately improve the process parameters. It should be particularly pointed out that all similar replacements and changes are obvious to those skilled in the art, and they are regarded as included in the present application. The method and application of the present application have been described by the preferred embodiments, and the related personnel can obviously modify or appropriately change and combine the method and application described in the present application without departing from the content, spirit and scope of the present application, to realize and apply the present application technology.

[0036] A 590MPa grade straight seam electric resistance welded (HFW) oil casing pipe, the chemical composition is as follows in percentage by weight:

[0037] C: 0.11%-0.14%, Si: 0.15%-0.30%, Mn: 0.80%-1.20%, P: ≤0.015%, S: ≤0.004%, Ti: 0.01%-0.03%, Cr: 0.10%-0.30%, V: 0.03%-0.06%, Mg: 0.004%-0.006%, Zr: 0.0006%-0.003%, Al: 0.02%-0.05%, N: ≤0.008%, the rest is Fe and inevitable elements.

[0038] Compared with the prior art, the scheme adopts low-carbon Cr-V composite design containing magnesium, the material has high strength after heat treatment, better low-temperature toughness and excellent SSC resistance; Mg refines inclusions, which can effectively change the shape and size of inclusions, and is beneficial to SSC performance and impact; Cr effectively improves the strength and SSC resistance; Pcm is lower than 0.23%, and the weldability is good.

[0039] The mechanism of each alloy component of the application is described in detail below, wherein the percentage symbol % represents the weight percentage:

[0040] C: is a carbide forming element, is the most effective element to ensure strength, can improve hardenability, and ensure material strength and hardness. The carbon content has an important influence on the carbon content and volume fraction of the final austenite and martensite. Only sufficient carbon can form sufficient carbon-rich residual austenite and can be stabilized to room temperature. If the carbon content is low, a large amount of alloy elements need to be added to improve the hardenability, which increases the cost of the alloy; at the same time, the thread performance is poor. If the content is too high, the weldability, plasticity and impact toughness of the product will be affected, and the best range is 0.11%-0.14%.

[0041] Si: can dissolve into ferrite and austenite, has a certain solid solution strengthening effect, can significantly improve the hardness and strength of the steel, and can improve the fatigue strength and fatigue ratio, but too high content will significantly reduce the plasticity and toughness of the steel, and the best range is 0.15%-0.30%.

[0042] Mn: manganese has a solid solution strengthening effect, can also increase the stability of austenite, is beneficial to improving the hardenability, and effectively ensures the strength of the steel. Manganese can reduce the martensite transformation temperature Ms and increase the content of residual austenite. Manganese has a significant effect on improving the strength of low-carbon and medium-carbon pearlitic steel. At the same time, manganese can also improve the hardness and wear resistance of the steel. However, too much manganese can increase the center segregation tendency of continuous casting billet, increase the banded structure in the steel plate, increase the brittleness of the steel plate, reduce the plasticity, and reduce the corrosion resistance. At the same time, it is easy to form MnS, which has a bad effect on the HIC resistance, and the best range is 0.80%-1.20%.

[0043] P, S, N: are inevitable impurity elements in steel, the lower the better, but too low will increase the production cost, the P≤0.015%, S≤0.004%, N≤0.006% of the application.

[0044] Ti: titanium is a strong nitrogen-fixing element, when adding about 0.015% Ti, high-temperature stable fine TiN precipitates can be formed during slab continuous casting, which can effectively prevent the growth of austenite grains during the heating process, and at the same time, it has obvious effect on improving the toughness of heat-affected zone during steel welding. More Ti content can obtain more TiC particles, which can improve the strength of the steel through strain-induced precipitation and phase transformation. At the same time, the precipitated TiC produces strong precipitation strengthening effect, which can ensure that the grains do not grow significantly during subsequent normalizing heat treatment of the steel pipe, thereby ensuring that the strength of the whole pipe after heat treatment meets the J55 performance requirements. However, too high content will increase the alloy cost. The best range is 0.01%-0.03%

[0045] Cr: chromium can improve the strength through solid solution strengthening and fine grain strengthening. Cr can be dissolved in the solid solution as Mn, which can improve the strength. After Cr element is dissolved in austenite, the stability of undercooled austenite is increased, the C curve is moved to the right, and the hardenability of the steel is improved. The steel has high strength and hardness, and improves the wear resistance of the steel. At the same time, Cr is a medium carbide forming element, among all kinds of carbides, chromium carbide is the smallest, which can uniformly distribute in the steel volume and hinder the movement of austenite grain boundary and the growth of austenite grain, thereby improving the temper brittleness of the steel; chromium also has the effect of reducing the corrosion rate of the steel in high-temperature carbon dioxide environment, slowing down the corrosion rate of the casing in the oil well, and improving the service life; but too high chromium content will significantly increase the brittle transition temperature of the steel, reduce the elongation, and easily form coarse carbides, which will lead to the deterioration of toughness. The appropriate range is 0.10%-0.30%.

[0046] V: vanadium carbonitride is uniformly precipitated in the form of fine dispersion in ferrite, which has fine grain strengthening effect, can significantly improve the yield strength and tensile strength of the material, and improve the low temperature impact toughness; when melted into austenite at high temperature, it can increase the hardenability of the steel; solid solution in ferrite has strong solid solution strengthening effect. During the quenching and tempering heat treatment process, it can hinder the grain growth, and can greatly improve the strength and toughness of the steel whether it is quenched or tempered. However, too high will increase the alloy cost, and the appropriate range is 0.03%-0.06%.

[0047] Mg: Magnesium has strong chemical activity, and has strong affinity with oxygen and sulfur. It is an effective refining agent, which can reduce the oxygen and sulfur content and the number of inclusions in steel, purify the liquid steel, and also has a significant modification effect on inclusions in steel, improving the performance of the steel. Trace amounts of magnesium can change the number, type, size, and distribution of sulfides, carbides, and carbonitrides. The inclusions treated by magnesium are mixed phases, with magnesium-containing oxides as the core. This structure is fine and dispersed in the steel, forming inclusions that improve the performance and corrosion resistance of the steel. The appropriate range is 0.004%-0.006%.

[0048] Zr: Trace amounts of zirconium have the effects of deoxidation, purification, grain refinement, and significant modification of inclusions, improving the low-temperature toughness of the steel. When mixed with Cr, it can significantly inhibit the recrystallization of the alloy and improve the alloy's resistance to SSC corrosion. The optimal range is 0.0006%-0.003%.

[0049] Als: Aluminum is a commonly used deoxidizer. Adding a small amount of aluminum to steel can refine the grains and improve the impact toughness. The Als content in the present invention is 0.02%-0.05%.

[0050] A manufacturing method of 590MPa grade straight seam electric resistance welding (HFW) oil casing, comprising molten iron pretreatment, molten steel smelting, secondary refining outside the furnace, slab continuous casting, reheating of continuous casting slab, rolling, cooling, coiling, HFW pipe making, and pipe heat treatment, specifically comprising the following steps:

[0051] 1) Smelting and continuous casting process:

[0052] Molten iron pretreatment, converter smelting - top blowing or top and bottom combined blowing, secondary refining outside the furnace, LF furnace light desulfurization treatment, and calcium treatment to control inclusion morphology and improve the ductility, toughness, and cold bending performance of the steel.

[0053] Continuous casting slab is made by continuous casting - electromagnetic stirring or dynamic soft reduction is used to improve the quality of the continuous casting slab.

[0054] 2) Rolling process:

[0055] The continuous casting slab is heated to 1100-1180℃ by a heating furnace, and then hot continuous rolling is used, with a finish rolling temperature of 750-820℃. The steel strip is cooled at a cooling rate of 16-21℃ / s after rolling.

[0056] The steel strip is coiled at a temperature of 540-590℃, which is beneficial to the uniformity and refinement of ferrite structure, and avoids the formation of non-uniform structure which adversely affects the SSC performance. The hot-rolled plate coil has a bainite structure, with a yield strength of 500MPa or more, a tensile strength of 590MPa or more, and an impact energy at -20℃ of 200J or more.

[0057] 3) Steel strip is welded into steel pipe by HFW unit.

[0058] 4) The pipe is heated to 850-890℃, and held for 25-35 min, and then water quenched.

[0059] After HFW pipe-making, the pipe is heated to 850-890℃, and held for 25-35 min, and then water quenched.

[0060] Then the pipe is heated to 480-540℃, and held for 35-58 min, and then water tempered. Rapid cooling after tempering can effectively inhibit high-temperature temper brittleness.

[0061] The final microstructure of the pipe is tempered sorbite; Pcm is lower than 0.23%, A / B / C / D inclusion level is lower than 1.0, each type of inclusion value is lower than 1.5, and banded structure is lower than 0.5.

[0062] The Cr-V composite design with low carbon and magnesium can provide high strength after heat treatment, better low-temperature toughness, and excellent SSC resistance. Mg can refine inclusions, effectively change the shape and size of inclusions, and is beneficial to SSC resistance and impact. Cr and V can effectively improve the strength and SSC resistance. Pcm is lower than 0.23%, and the pipe has good weldability. The pipe is subjected to quenching and tempering heat treatment, and the final microstructure is tempered sorbite, which ensures the consistency of the pipe body and weld performance.

[0063]

EMBODIMENT

[0064] A 590MPa grade straight seam resistance welded (HFW) oil casing and a manufacturing method thereof are provided, and the specific implementation is as follows:

[0065] Table 1 is the chemical composition of the straight seam resistance welded (HFW) oil casing of the embodiment; Table 2 is the heating, rolling, and cooling process parameters of the embodiment; Table 4 is the heat treatment process of the embodiment; and Table 4 is the quenching and tempering mechanical property test results of the embodiment.

[0066] Table 1 Chemical composition of the embodiment (wt%)

[0067] Examples C Si Mn P S Ti Cr V Mg Zr N Pcm 1 0.11 0.16 0.86 0.013 0.002 0.02 0.30 0.04 0.004 0.002 0.005 0.19 2 0.12 0.18 1.16 0.012 0.003 0.03 0.22 0.05 0.005 0.0008 0.006 0.23 3 0.13 0.20 1.10 0.008 0.001 0.02 0.10 0.03 0.004 0.003 0.006 0.22 4 0.12 0.25 1.20 0.011 0.002 0.01 0.15 0.06 0.004 0.002 0.004 0.23 5 0.11 0.29 0.99 0.010 0.003 0.02 0.25 0.04 0.006 0.001 0.007 0.21 6 0.12 0.22 1.00 0.012 0.004 0.02 0.18 0.05 0.005 0.002 0.008 0.21 7 0.11 0.23 1.06 0.012 0.003 0.03 0.27 0.05 0.004 0.002 0.004 0.22 8 0.12 0.24 1.15 0.010 0.003 0.01 0.13 0.04 0.005 0.003 0.005 0.21

[0068] Table 2 Heating, rolling, and cooling process parameters

[0069]

[0070]

[0071] Table 3 Quenching and tempering process

[0072]

[0073] Table 4 Quenching and tempering mechanical and corrosion resistance properties

[0074]

[0075] From Tables 1-4, it can be seen that the 590MPa grade H2S corrosion resistant resistance welded oil casing produced by adopting the component design and rolling and coiling process of the application meets the requirements of the M65 grade mechanical properties and corrosion resistance performance of API SPEC 5CT standard.

[0076] The application adopts low-carbon Cr-V composite design containing magnesium, the material has high strength after heat treatment, better low-temperature toughness and excellent SSC resistance performance; Mg refines inclusions, effectively changes the shape and size of inclusions, and is beneficial to SSC performance and impact; Cr and V effectively improve the strength and SSC resistance performance; Pcm is lower than 0.23%, and the weldability is good; the whole pipe is subjected to quenching and tempering heat treatment, and the final organization is tempered sorbite, which ensures the consistency of the pipe body and the weld performance.

[0077] The above only describes the preferred specific embodiments of the application, but the protection scope of the application is not limited to this, any person skilled in the art can make equivalent replacement or change according to the technical scheme and the inventive concept of the application within the technical range disclosed by the application, which should be covered in the protection scope of the application.

Claims

1. A 590 MPa grade H2S stress corrosion resistant electric resistance welded oil casing characterized in that, Its chemical composition by weight percentage is as follows: C: 0.11%~0.14%, Si: 0.15%~0.30%, Mn: 0.80%~1.20%, P: ≤0.015%, S: ≤0.004%, Ti: 0.01%~0.03%, Cr: 0.10%~0.25%, V: 0.03%~0.04%, Mg: 0.004%~0.006%, Zr: 0.0006%~0.003%, Als: 0.02%~0.05%, N: ≤0.008%, Pcm less than 0.23%, the remainder being Fe and unavoidable elements; Its manufacturing method specifically includes the following steps: 1) Continuous casting in smelting: Ladle refining, LF furnace desulfurization treatment, and calcium treatment; Slabs are continuously cast into continuously cast billets, and the continuous casting process employs electromagnetic stirring or dynamic light reduction. 2) Rolling: The continuously cast slab is heated to 1100~1180℃ in a heating furnace, and then hot continuous rolling is carried out, with a final rolling temperature of 750~820℃; 3) Cooling: The rolled steel strip is cooled at a rate of 16~21℃ / s; 4) Winding: After cooling, the coil is wound at a temperature of 540~590℃. The hot-rolled coil has a bainitic structure with a yield strength of 500MPa or more, a tensile strength of 590MPa or more, and an impact energy of 200J or more at -20℃. 5) The steel strip is processed into steel pipes by high-frequency / medium-frequency resistance welding using the HFW unit; 6) Heat treatment of the entire tube: Heat the entire tube to 850~890℃, hold for 25~35 minutes, and then quench in water; then heat the entire tube to 480~540℃ and hold for 35~58 minutes.

2. A method of manufacturing a 590 MPa grade H2S resistant stress corrosion resistant electric resistance welded oil casing according to claim 1, characterized in that, Specifically, the steps include the following: 1) Continuous casting in smelting: Ladle refining, LF furnace desulfurization treatment, and calcium treatment; Slabs are continuously cast into continuously cast billets, and the continuous casting process employs electromagnetic stirring or dynamic light reduction. 2) Rolling: The continuously cast slab is heated to 1100~1180℃ in a heating furnace, and then hot continuous rolling is carried out, with a final rolling temperature of 750~820℃; 3) Cooling: The rolled steel strip is cooled at a rate of 16~21℃ / s; 4) Winding: After cooling, the coil is wound at a temperature of 540~590℃. The hot-rolled coil has a bainitic structure with a yield strength of 500MPa or more, a tensile strength of 590MPa or more, and an impact energy of 200J or more at -20℃. 5) The steel strip is processed into steel pipes by high-frequency / medium-frequency resistance welding using the HFW unit; 6) Heat treatment of the entire tube: Heat the entire tube to 850~890℃, hold for 25~35 minutes, and then quench in water; then heat the entire tube to 480~540℃ and hold for 35~58 minutes.

3. The manufacturing method of a 590MPa-grade H2S stress corrosion resistant resistance welding oil sleeve according to claim 2, characterized in that, In step 1), the smelting is carried out by top blowing or a combination of top and bottom blowing.

4. The manufacturing method of a 590MPa-grade H2S stress corrosion resistant resistance welding oil sleeve according to claim 2, characterized in that, In step 6), the final microstructure of the steel pipe is tempered sorbite; the inclusion level of A / B / C / D types is below 1.0, the sum of each type is below 1.5, and the banded structure is below 0.5.

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