High-strength high-toughness hydrogen-induced delayed fracture-resistant petroleum casing material and preparation method thereof

Abstract

The invention provides a high-strength high-toughness hydrogen-induced delayed fracture-resistant oil casing material, and belongs to the field of oil exploitation equipment. The contents of Mn, Mo and V are optimized, and other components are matched, so that the material has good hydrogen-induced delayed fracture resistance while having high strength and high toughness. Experimental results show that the mechanical properties of the casing material provided by the invention are as follows: the tensile strength is not less than 1260Mpa, the yield strength is not less than 1200Mpa, the longitudinal impact energy at 0 DEG C is not less than 100J, and the transverse impact energy is not less than 70J; a notch constant-load delayed fracture test is carried out, the notch constant-load critical fracture stress ratio n is not smaller than 0.8, and fracture does not occur after more than 100 h.

Description

Technical Field

[0001] The invention relates to the field of oil production equipment, and in particular to a high-strength and high-toughness oil casing material that resists hydrogen-induced delayed fracture and a preparation method thereof. Background Art

[0002] Oil casing is a steel pipe used to support the well wall of oil and gas wells to ensure the normal operation of the entire oil well during the drilling process and after completion. It is the lifeline for maintaining the operation of oil wells. As the depth of the oil well increases, the temperature and pressure in the well increase accordingly, and the geological environment in which the oil casing is in service has changed significantly. Ultra-deep wells reaching 6,000 meters or even more than 8,000 meters are often accompanied by complex well conditions such as stratum slip, rock salt layers, earthquakes, high temperatures, and high pressures, and the underground geological conditions are harsh. In deep wells, oil casing mainly considers anti-squeezing and high-temperature strength. At the wellhead, it is necessary to consider tensile strength, pipe string connection sealing performance, and the ability to resist internal pressure. Improving the steel grade is the most direct and effective way to improve the comprehensive performance of the casing.

[0003] In addition, in order to improve efficiency, reduce costs and reduce casing weight, the demand for high-grade 170ksi to 200ksi casing in oilfield exploitation has further increased. Therefore, the change in the service environment has put forward higher requirements on the comprehensive mechanical properties, performance and life of oil casing, especially on the matching of strength and toughness. Hydrogen-induced delayed cracking usually occurs suddenly when materials or parts are subjected to the combined action of stress and hydrogen, usually without precursors, causing great harm and seriously affecting the safety and efficiency of mining. The existing high-grade steel oil casing of the US API standard and the UK Department of Energy guidance standard is difficult to meet.

[0004] In order to solve the above problems, many scholars have made useful explorations in the comprehensive performance control of this type of steel. CN111607744A discloses a thick-walled, high-strength, high-toughness oil casing and its manufacturing method. By controlling the appropriate amount of Mn and Mo content (0.5-1.2%, 0.6-1.2%), it has good impact toughness (0°C transverse Charpy impact energy ≥ 110J), but it also causes the tensile strength and yield strength of this type of steel to be insufficient, and it does not reach the 170ksi level, which is not conducive to structural safety. CN105441801A discloses an ultra-high strength and ultra-high toughness oil casing and its TMCP manufacturing method. By controlling the lower carbon content (0.1-0.22%) and the appropriate amount of Mo, Cr, V content (0.2-0.6%, not added, 0.05-0.15%), it has good impact toughness (0°C transverse Charpy impact energy ≥ 120J), but it also causes the tensile strength and yield strength of this type of steel to be insufficient, and it does not meet the high strength requirements. CN101629476A discloses a high-strength and high-toughness petroleum casing resistant to low temperatures of -40 to -80°C. The appropriate Mo and V contents (0.15 to 1.25%, 0.01 to 0.2%) are controlled by component optimization design to cause delta ferrite to appear in the structure, so that the lateral impact and longitudinal impact of the material at 0°C are lower; adding 0.01 to 0.2% V can refine the austenite grains and greatly improve the tensile strength, but the material's resistance to hydrogen-induced delayed fracture is not discussed, which is not conducive to use in complex underground working conditions. CN107916366A discloses a low alloy steel for producing 170ksi steel grade steel pipes. By optimizing the composition design and controlling the appropriate amount of Mo and V content (0.75-0.86%, 0.08-0.15%), the austenite grains can be refined and the tensile strength can reach ≥1250MPa; adding 0.02-2.2% Ni reduces the yield strength. Although the tensile strength reaches the 170ksi level, the impact absorption energy at 0°C is only ≥80J. CN102747289A discloses an ultra-high strength steel for oil casing, oil casing and its manufacture. By controlling the use of appropriate C (0.25-0.36%) and relatively high Cr (0.80-1.40%), the yield strength of the casing reaches above 1180MPa, and an appropriate heat treatment process is adopted so that the upper and lower pipe columns of the casing can be directly connected to the Φ177.8 specification casing, which is convenient for on-site operations; in addition, adding 0-0.05% Ti is beneficial to improving the anti-collapse performance, but the material strength surplus is low and the impact performance (≤100J) is lacking.CN116657045A discloses a 160ksi-grade high-strength and tough non-standard oil casing and a production method thereof. By combining high-temperature rolling with direct online quenching, the 0°C transverse and longitudinal Charpy impact Akv of the steel pipe are not less than 110J and 120J respectively; however, as the impact toughness increases, the material strength is severely lost, the tensile strength is ≥1200MPa, and the yield strength reaches more than 1100MPa, which only reaches the 160ksi level, and the strength performance is lacking.

[0005] It can be seen that the existing high-strength and high-toughness oil casing materials still have shortcomings in matching high strength and high toughness. Summary of the invention

[0006] The purpose of the present invention is to provide a high-strength, high-toughness, hydrogen-induced delayed fracture resistant oil casing material and a preparation method thereof. The oil casing material provided by the present invention has high strength and high toughness while also having good hydrogen-induced delayed fracture resistance, and can be used for oil production in harsh environments such as ultra-deep wells.

[0007] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0008] The invention provides a high-strength and high-toughness hydrogen-induced delayed fracture resistant petroleum casing material. The chemical composition of the high-strength and high-toughness hydrogen-induced delayed fracture resistant petroleum casing material comprises, by mass percentage, C: 0.22-0.30%, Si: 0.10-0.40%, Mn: 0.10-0.40%, P: ≤0.012%, S: ≤0.002%, Cr: 0.76-1.0%, Mo: 1.25-1.7%, Nb: 0.01-0.04%, V: 0.30-0.36%, Al: 0.005-0.04%, B: 0.0015-0.005%, and the balance of Fe.

[0009] Preferably, the chemical composition of the high-strength and high-toughness hydrogen-induced delayed fracture resistant petroleum casing material includes, by mass percentage: C: 0.22-0.29%, Si: 0.12-0.35%, Mn: 0.15-0.36%, P: ≤0.012%, S: ≤0.002%, Cr: 0.76-0.95%, Mo: 1.30-1.67%, Nb: 0.012-0.035%, V: 0.26-0.34%, Al: 0.008-0.035%, B: 0.0016-0.0045%, and the balance Fe.

[0010] Preferably, the chemical composition of the high-strength and high-toughness hydrogen-induced delayed fracture resistant petroleum casing material includes, by mass percentage: C: 0.22-0.27%, Si: 0.13-0.34%, Mn: 0.17-0.34%, P: ≤0.012%, S: ≤0.002%, Cr: 0.78-0.94%, Mo: 1.31-1.65%, Nb: 0.016-0.033%, V: 0.28-0.34%, Al: 0.012-0.032%, B: 0.0018-0.0042%, and the balance Fe.

[0011] Preferably, the chemical composition of the high-strength and high-toughness hydrogen-induced delayed fracture resistant petroleum casing material includes, by mass percentage: C: 0.23-0.27%, Si: 0.14-0.32%, Mn: 0.18-0.32%, P: ≤0.012%, S: ≤0.002%, Cr: 0.79-0.92%, Mo: 1.35-1.60%, Nb: 0.017-0.032%, V: 0.28-0.33%, Al: 0.015-0.031%, B: 0.0019-0.0041%, and the balance Fe.

[0012] Preferably, the chemical composition of the high-strength and high-toughness hydrogen-induced delayed fracture resistant petroleum casing material includes, by mass percentage: C: 0.24-0.27%, Si: 0.16-0.31%, Mn: 0.19-0.31%, P: ≤0.012%, S: ≤0.002%, Cr: 0.81-0.91%, Mo: 1.40-1.60%, Nb: 0.018-0.031%, V: 0.28-0.32%, Al: 0.018-0.031%, B: 0.0021-0.0038%, and the balance Fe.

[0013] The present invention also provides a method for preparing the high-strength, high-toughness, hydrogen-induced delayed fracture resistant petroleum casing material described in the above technical solution, comprising: smelting, hot rolling and tempering heat treatment of the alloy raw materials in sequence to obtain tempered finished steel.

[0014] Preferably, the hot rolling is preceded by heat preservation, the heat preservation temperature is 1200-1280°C, and the heat preservation time is greater than 3h; the starting temperature of the hot rolling is 1100-1190°C, and the final rolling temperature is 1020-1080°C.

[0015] Preferably, the hot rolling further includes cooling, wherein the cooling is water cooling to 750° C. and then air cooling to room temperature.

[0016] Preferably, the tempering heat treatment includes quenching heat treatment and tempering heat treatment performed sequentially.

[0017] Preferably, the quenching temperature of the quenching heat treatment is 880-920° C., and the holding time is 30-60 min; the tempering temperature of the tempering heat treatment is 640-680° C., and the holding time is 75-120 min.

[0018] The invention provides a high-strength and high-toughness hydrogen-induced delayed fracture resistant petroleum casing material. The chemical composition of the high-strength and high-toughness hydrogen-induced delayed fracture resistant petroleum casing material includes, by mass percentage: C: 0.22-0.30%, Si: 0.10-0.40%, Mn: 0.10-0.40%, P: ≤0.012%, S: ≤0.002%, Cr: 0.76-1.0%, Mo: 1.25-1.7%, Nb: 0.01-0.04%, V: 0.30-0.36%, Al: 0.005-0.04%, B: 0.0015-0.005%, and the balance Fe. The invention optimizes the content of Mn, Mo and V, and coordinates other components to make the material have good hydrogen-induced delayed fracture resistance while having high strength and high toughness. Experimental results show that the mechanical properties of the casing material provided by the present invention are as follows: tensile strength is not less than 1260 MPa, longitudinal impact energy is not less than 100 J, and transverse impact energy is not less than 70 J; in a constant load notch delayed fracture test, the notch constant load critical fracture stress ratio n is not less than 0.8, and it does not break for more than 100 h. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 The microstructure of the material prepared in Example 1;

[0020] Figure 2 The microstructure of the material prepared in Example 2;

[0021] Figure 3 The microstructure diagram of the material prepared in Comparative Example 1;

[0022] Figure 4 The microstructure diagram of the material prepared in Comparative Example 2;

[0023] Figure 5 This is a constant load notch tensile test sample. DETAILED DESCRIPTION

[0024] The invention provides a high-strength and high-toughness hydrogen-induced delayed fracture resistant petroleum casing material. The chemical composition of the high-strength and high-toughness hydrogen-induced delayed fracture resistant petroleum casing material comprises, by mass percentage, C: 0.22-0.30%, Si: 0.10-0.40%, Mn: 0.10-0.40%, P: ≤0.012%, S: ≤0.002%, Cr: 0.76-1.0%, Mo: 1.25-1.7%, Nb: 0.01-0.04%, V: 0.25-0.36%, Al: 0.005-0.04%, B: 0.0015-0.005%, and the balance of Fe.

[0025] In terms of mass percentage, the high-strength, high-toughness, hydrogen-induced delayed fracture resistant petroleum casing material provided by the present invention includes C0.22% to 0.30%, preferably 0.22% to 0.29%, more preferably 0.22% to 0.27%, further preferably 0.23% to 0.27%, and further preferably 0.24% to 0.27%. In the present invention, the C has a significant effect on improving the strength of steel through solid solution strengthening and precipitation strengthening. The present invention limits the C content within the above range to improve the strength, plasticity, toughness and other properties of the material, and avoids the negative impact of excessive C content on the plasticity and toughness of the steel.

[0026] In terms of mass percentage, the high-strength and high-toughness hydrogen-induced delayed fracture resistant petroleum casing material provided by the present invention includes Si 0.10% to 0.40%, preferably 0.12% to 0.35%, more preferably 0.13% to 0.34%, further preferably 0.14% to 0.32%, and further preferably 0.16% to 0.31%. In the present invention, the Si, as an important reducing agent and deoxidizer in the steelmaking process, can be dissolved in ferrite and austenite to improve the hardness and strength of the steel. By limiting the content of Si within the above range, the present invention can reduce the precipitation tendency of Fe3C and avoid excessive Si content, which reduces the plasticity and toughness of the steel.

[0027] In terms of mass percentage, the high-strength, high-toughness, hydrogen-induced delayed fracture resistant petroleum casing material provided by the present invention includes 0.10% to 0.40% Mn, preferably 0.16% to 0.35%, more preferably 0.17% to 0.34%, further preferably 0.18% to 0.32%, and further preferably 0.19% to 0.31%. In the present invention, the Mn can improve the hardenability of the steel, enhance the strength, toughness, and hardness, form MnS inclusions with the S element, reduce the influence of S, and improve the hot working performance of the steel. By limiting the content of Mn to the above range, the present invention avoids the problem that too high Mn content exacerbates the segregation of the continuous casting billet, increases the banded structure grade of the steel pipe, deteriorates the uniformity of the structure, is unfavorable to the low-temperature toughness, and reduces the corrosion resistance of the material; the material has high strength and high toughness while also having good hydrogen-induced delayed fracture resistance.

[0028] The high-strength, high-toughness, hydrogen-induced delayed fracture resistant petroleum casing material provided by the present invention includes P≤0.012% by mass percentage. In the present invention, the P is an impurity element, which causes a significant decrease in plasticity and impact toughness, especially at low temperatures, making the steel material significantly brittle. The present invention limits the P content range to no more than 0.012%, reducing the influence of P on material properties while also reducing costs.

[0029] The high-strength, high-toughness, hydrogen-induced delayed fracture resistant petroleum casing material provided by the present invention includes S≤0.002% by mass percentage. In the present invention, the S is an impurity element, which is detrimental to the ductility, toughness, weldability and corrosion resistance of steel; if S exists in the form of FeS in steel, it can also produce "hot brittleness" during hot working. The present invention limits the S content range to no more than 0.002%, reducing the influence of S on material properties.

[0030] In terms of mass percentage, the high-strength, high-toughness, hydrogen-induced delayed fracture resistant petroleum casing material provided by the present invention includes Cr0.76% to 1.0%, preferably 0.76% to 0.95%, more preferably 0.78% to 0.94%, further preferably 0.79% to 0.92%, and further preferably 0.81% to 0.91%. In the present invention, the Cr can increase the hardenability of the steel and has a secondary hardening effect, which can improve the strength, hardness and wear resistance of the steel without making the steel brittle, but will reduce the elongation and cross-sectional shrinkage; the main role of Cr in the quenched and tempered structure is to improve the hardenability, so that the steel has better comprehensive mechanical properties after quenching and tempering. The present invention avoids the problem of excessive Cr addition leading to the precipitation and aggregation growth of Cr-containing carbides at the original austenite grain boundaries during tempering, which seriously damages the low-temperature toughness of the steel, and cooperates with other components to make the material have high strength and high toughness.

[0031] In terms of mass percentage, the high-strength, high-toughness, hydrogen-induced delayed fracture resistant petroleum casing material provided by the present invention includes Mo1.25% to 1.7%, preferably 1.30% to 1.67%, more preferably 1.31% to 1.65%, further preferably 1.35% to 1.60%, and further preferably 1.40% to 1.60%. In the present invention, the Mo element as an alloying element can effectively improve the strength of the steel, especially the high-temperature strength and toughness, improve the corrosion resistance of the steel in acidic solution; improve the wear resistance of the steel, improve the hardenability and weldability; the Mo element can greatly improve the creep resistance of the ferrite, effectively inhibit the aggregation of cementite at 450 to 600°C, promote the precipitation of special carbides, produce secondary hardening, and improve the hardness and strength of the material; and the Mo element itself is a good carbide-forming element. Compared with the Cr element, the Mo element tends to form M2C carbides, and the size of the carbides is smaller, which plays a dispersion strengthening role and improves the tempering resistance of the material. The present invention limits the content of Mo to the above range and combines it with other components to make the material have high strength and high toughness.

[0032] The high-strength, high-toughness, hydrogen-induced delayed fracture resistant petroleum casing material provided by the present invention comprises Nb 0.01% to 0.04%, preferably 0.012% to 0.035%, more preferably 0.016% to 0.033%, further preferably 0.017% to 0.032%, and further preferably 0.018% to 0.031%, in terms of mass percentage. In the present invention, the Nb is one of the most important microalloying elements, partially dissolved in solid solution, and plays a solid solution strengthening role; when present in the form of carbides, nitrides and oxide particles, it can increase the tempering stability of steel and have a secondary hardening effect; trace Nb can improve the strength of steel without affecting the plasticity or toughness of steel; due to the effect of refining grains, it can improve the impact toughness of steel and reduce its brittle transition temperature; during the rolling process, the solid solution Nb significantly increases the recrystallization temperature of the steel, so that the rolling process of the steel can be completed within a higher temperature range, thereby reducing the internal stress of the steel. The present invention limits the Nb content within the above range and combines it with other components to make the material have high strength and high toughness.

[0033] In terms of mass percentage, the high-strength, high-toughness, hydrogen-induced delayed fracture resistant petroleum casing material provided by the present invention includes V0.25% to 0.36%, preferably 0.26% to 0.34%, more preferably 0.28% to 0.34%, further preferably 0.28% to 0.33%, and further preferably 0.28% to 0.32%. In the present invention, the V has the functions of refining the structure and grains, improving the strength and toughness, and reducing the sensitivity to overheating; V is dissolved in austenite at high temperature, hindering the growth of austenite grains and improving the hardenability of the material; increasing the V content in quenched and tempered steel can increase the tempering stability of the steel, so that the steel maintains the shape of martensitic laths during tempering, or precipitates vanadium carbide during tempering to produce a secondary hardening effect, thereby improving the strength of the steel. The present invention limits the V content within the above range and can improve the strength of the material in combination with other components.

[0034] In terms of mass percentage, the high-strength and high-toughness hydrogen-induced delayed fracture resistant petroleum casing material provided by the present invention includes Al 0.005% to 0.04%, preferably 0.008% to 0.035%, more preferably 0.012% to 0.032%, further preferably 0.015% to 0.031%, and further preferably 0.018% to 0.031%. In the present invention, the Al, as a deoxidizer or alloying element, mainly functions in steel to refine grains and fix nitrogen in steel, thereby significantly improving the impact toughness of steel and reducing cold brittleness and aging tendency; aluminum can also improve the corrosion resistance of steel, especially when used in combination with platinum, copper, silicon, chromium and other elements, the effect is better. The present invention limits the content of Al to the above range, and can improve the strength and toughness of the material in combination with other components.

[0035] In terms of mass percentage, the high-strength and high-toughness hydrogen-induced delayed fracture resistant petroleum casing material provided by the present invention includes B 0.0015% to 0.005%, preferably 0.0016% to 0.0045%, more preferably 0.0018% to 0.0042%, further preferably 0.0019% to 0.0041%, and further preferably 0.0021% to 0.0038%. In the present invention, the B is a surface active element, and the atomic radius is very small. It is very easy to diffuse to the austenite grain boundary at high temperature. Boron gathers at the austenite grain boundary, the grain boundary energy is reduced, the austenite stability is increased, the austenite grain growth is inhibited, and the toughness is improved. The present invention limits the content of B within the above range and cooperates with other components to improve the toughness of the material.

[0036] Measured by mass percentage, the high-strength, high-toughness, hydrogen-induced delayed fracture resistant petroleum casing material provided by the present invention also includes a balance of Fe. In the present invention, the Fe is a matrix element.

[0037] The present invention optimizes the contents of Mn, Mo and V and combines other components to ensure that the material has high strength and high toughness as well as good resistance to hydrogen-induced delayed fracture.

[0038] The present invention also provides a method for preparing the high-strength, high-toughness, hydrogen-induced delayed fracture resistant petroleum casing material described in the above technical solution, comprising: smelting, hot rolling and tempering heat treatment of the alloy raw materials in sequence to obtain tempered finished steel.

[0039] The present invention has no particular limitation on the sources of the raw materials, and the raw materials may be prepared using commercially available products or well-known preparation methods known to those skilled in the art.

[0040] In the present invention, the smelting includes vacuum melting, high temperature high vacuum refining and alloying performed in sequence. The vacuum degree of the vacuum melting is 0.5 to 1.5 Pa. The present invention has no particular limitation on the temperature of the vacuum melting, as long as the steel billet is melted. The high temperature high vacuum refining time is 5 to 15 minutes. The present invention has no particular limitation on the temperature of the high temperature high vacuum refining, as long as the molten steel is kept in a molten state. In the present invention, the smelting is preferably carried out in a vacuum furnace.

[0041] In the present invention, the alloying is preferably performed under argon protection.

[0042] After smelting is completed, the present invention preferably casts the alloy liquid obtained by the smelting to obtain a steel ingot, and then hot-rolls it. The present invention has no particular limitation on the casting, and a casting method commonly used in the art can be used. The present invention has no particular limitation on the type of the steel ingot, and a type of steel ingot commonly used in the art can be used. The present invention preferably uses a cannonball-shaped steel ingot.

[0043] The present invention preferably heat-insulates the steel ingot before hot rolling; the heat-insulating temperature is preferably 1200-1280°C; the heating rate is preferably 9-11°C / s; and the heat-insulating time is preferably greater than 3 hours. The present invention heat-insulates the steel ingot to transform it into complete austenite.

[0044] In the present invention, the starting rolling temperature of the hot rolling is preferably 1100-1190° C., and the finishing rolling temperature is preferably 1020-1080° C. In the present invention, the hot rolling is preferably completely longitudinally rolled. In the present invention, the thickness of the rolled steel is preferably 17-19 mm.

[0045] After hot rolling the steel ingot, the present invention preferably further comprises cooling, and the cooling is preferably water cooling to 750° C., and then air cooling to room temperature. In the present invention, the rolled steel is obtained after the cooling.

[0046] The present invention performs quenching and tempering heat treatment on the obtained rolled steel to obtain quenched and tempered finished steel.

[0047] In the present invention, the quenching and tempering heat treatment preferably includes quenching and tempering treatment performed in sequence. In the present invention, the temperature of the quenching treatment is preferably 880-920°C, and the holding time is preferably 30-60°C. In the present invention, the tempering temperature of the tempering treatment is preferably 640-680°C, and the holding time is preferably 75-120 minutes.

[0048] The preparation method provided by the present invention optimizes the parameters of the quenching and tempering heat treatment, so that the structure of the steel is transformed into troostite and a small amount of martensite, the grains are fine, and the tensile strength, yield strength and toughness of the material are improved.

[0049] The technical solutions in the present invention will be described clearly and completely below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0050] Example 1

[0051] A 75kg vacuum furnace was used to refine the test steel according to the composition of Example 1 in Table 1 and to perform rolling and tempering heat treatment. The specific steps are as follows:

[0052] 1) Prepare raw materials: prepare steel billets and alloy materials according to the components shown in Table 1;

[0053] 2) Smelting: The steel billet is loaded into the furnace, vacuumed to 1Pa, heated until the steel billet is melted, the molten steel is refined at high temperature and high vacuum for 10 minutes, the protective gas argon is filled, the alloy material is added, the alloy material is completely melted, and the profile is cast. The profile is a shell-shaped steel ingot.

[0054] 3) Hot rolling: First, the steel ingot is heated to the complete austenitization temperature of 1250℃ at a speed of 10℃ / s, kept at this temperature for 4 hours, and then fully longitudinally rolled, with the starting rolling temperature of 1150℃ and the final rolling temperature of 1050℃; the finished product thickness is 18mm. Then it enters the rapid cooling device for cooling, sprays water to below 750℃, and then air cools to room temperature to obtain rolled steel.

[0055] 4) Quenching and tempering heat treatment: the rolled steel is subjected to quenching at 880° C. for 45 min and tempering at 660° C. for 100 min to obtain a quenched and tempered finished steel plate.

[0056] Table 1 Steel composition of examples and comparative examples / wt%

[0057]

[0058]

[0059] Examples 2 to 4 and Comparative Examples 1 to 7

[0060] The ingredients of Examples 2 to 4 and Comparative Examples 1 to 7 are detailed in Table 1, the parameters of the quenching and tempering heat treatment are detailed in Table 2, and the other parameters are consistent with those of Example 1.

[0061] The microstructures of the materials prepared in Examples 1 and 2 and Comparative Examples 1 and 2 were observed using an optical microscope. Figures 1 to 4 As shown in the figure, it can be seen that compared with comparative examples 1 and 2, the structures of embodiments 1 and 2 are refined, and no obvious segregation bands appear, and the martensite laths are clearly visible, indicating that the structure can be optimized by properly matching the content of Mn, Mo and V.

[0062] According to GB / T 228.1-2010 "Metallic Material Tensile Test Part 1: Room Temperature Test Method", GB / T 229-2007 "Metallic Material Charpy Pendulum Impact Test Method" and other standards, the mechanical properties of the steel plates obtained in Examples 1 to 4 and Comparative Examples 1 to 7 were tested, and the results are shown in Table 3. The yield strength of the materials provided by the present invention is greater than 1200MPa, the tensile strength is greater than 1260MPa, the longitudinal impact energy at 0°C is greater than 100J, and the transverse impact energy is greater than 70J. In the notch load test, the notch tensile specimen is subjected to constant load stretching in Walpole corrosion inhibition solution, and its notch load critical fracture stress ratio n is not less than 0.8, and it does not break for more than 100h. The constant load notch tensile test adopts Figure 5 The pattern is tested.

[0063] Table 2 Quenching and tempering heat treatment parameters

[0064]

[0065]

[0066] Table 3 Performance test results

[0067]

[0068] By comparing Example 4 with Comparative Examples 5 to 7, it can be seen that by increasing the Mn content, decreasing the Mo content or decreasing the V content, the performance of the material decreases to varying degrees, indicating that the present invention optimizes the contents of Mn, Mo and V and combines other ingredients to make the material have high strength and high toughness while also having good resistance to hydrogen-induced delayed fracture.

[0069] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A high-strength, high-toughness, hydrogen-induced delayed fracture resistant petroleum casing material, characterized in that: The chemical composition of the high-strength and high-toughness hydrogen-induced delayed fracture resistant petroleum casing material includes, by mass percentage, C: 0.22-0.30%, Si: 0.10-0.40%, Mn: 0.10-0.40%, P: ≤0.012%, S: ≤0.002%, Cr: 0.76-1.0%, Mo: 1.25-1.7%, Nb: 0.01-0.04%, V: 0.25-0.36%, Al: 0.005-0.04%, B: 0.0015-0.005%, and the balance of Fe.

2. The high-strength and high-toughness hydrogen-induced delayed fracture resistant petroleum casing material according to claim 1 is characterized in that: The chemical composition of the high-strength and high-toughness hydrogen-induced delayed fracture resistant petroleum casing material includes, by mass percentage, C: 0.22-0.29%, Si: 0.12-0.35%, Mn: 0.15-0.36%, P: ≤0.012%, S: ≤0.002%, Cr: 0.76-0.95%, Mo: 1.30-1.67%, Nb: 0.012-0.035%, V: 0.26-0.34%, Al: 0.008-0.035%, B: 0.0016-0.0045%, and the balance Fe.

3. The high-strength, high-toughness, hydrogen-induced delayed fracture resistant petroleum casing material according to claim 2 is characterized in that: The chemical composition of the high-strength and high-toughness hydrogen-induced delayed fracture resistant petroleum casing material includes, by mass percentage, C: 0.22-0.27%, Si: 0.13-0.34%, Mn: 0.17-0.34%, P: ≤0.012%, S: ≤0.002%, Cr: 0.78-0.94%, Mo: 1.31-1.65%, Nb: 0.016-0.033%, V: 0.28-0.34%, Al: 0.012-0.032%, B: 0.0018-0.0042%, and the balance of Fe.

4. The high-strength, high-toughness, hydrogen-induced delayed fracture resistant petroleum casing material according to claim 3 is characterized in that: The chemical composition of the high-strength and high-toughness hydrogen-induced delayed fracture resistant petroleum casing material includes, by mass percentage, C: 0.23-0.27%, Si: 0.14-0.32%, Mn: 0.18-0.32%, P: ≤0.012%, S: ≤0.002%, Cr: 0.79-0.92%, Mo: 1.35-1.60%, Nb: 0.017-0.032%, V: 0.28-0.33%, Al: 0.015-0.031%, B: 0.0019-0.0041%, and the balance Fe.

5. The high-strength, high-toughness, hydrogen-induced delayed fracture resistant petroleum casing material according to claim 4 is characterized in that: The chemical composition of the high-strength and high-toughness hydrogen-induced delayed fracture resistant petroleum casing material includes, by mass percentage, C: 0.24-0.27%, Si: 0.16-0.31%, Mn: 0.19-0.31%, P: ≤0.012%, S: ≤0.002%, Cr: 0.81-0.91%, Mo: 1.40-1.60%, Nb: 0.018-0.031%, V: 0.28-0.32%, Al: 0.018-0.031%, B: 0.0021-0.0038%, and the balance Fe.

6. The method for preparing the high-strength, high-toughness, hydrogen-induced delayed fracture resistant petroleum casing material according to any one of claims 1 to 5, comprising: The alloy raw materials are sequentially smelted, hot rolled and subjected to quenching and tempering heat treatment to obtain quenched and tempered finished steel.

7. The preparation method according to claim 6, characterized in that: The hot rolling is preceded by heat preservation, the heat preservation temperature is 1200-1280°C, and the heat preservation time is greater than 3h; the starting rolling temperature of the hot rolling is 1100-1190°C, and the final rolling temperature is 1020-1080°C.

8. The preparation method according to claim 6 or 7, characterized in that: The hot rolling process also includes cooling, wherein the cooling is performed by water cooling to 750° C. and then air cooling to room temperature.

9. The preparation method according to claim 6, characterized in that: The quenching and tempering heat treatment includes quenching heat treatment and tempering heat treatment performed in sequence.

10. The preparation method according to claim 9, characterized in that: The quenching temperature of the quenching heat treatment is 880-920° C., and the holding time is 30-60 min; the tempering temperature of the tempering heat treatment is 640-680° C., and the holding time is 75-120 min.

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