Steel for 110Ksi quenched and tempered coiled tubing, steel pipe and production method of steel pipe

Abstract

The steel comprises the following chemical components in percentage by weight: 0.10%-0.20% of C, 0.16%-0.30% of Si, 0.75%-1.05% of Mn, less than or equal to 0.012% of P, less than or equal to 0.001% of S, 0.20%-0.30% of Cu, 0.10%-0.15% of Ni, 0.52%-0.71% of Cr, 0.03%-0.08% of Mo, 0.010%-0.020% of Nb, 0.010%-0.020% of Ti, 0.0020%-0.0030% of Ca, 0.020%-0.030% of Al, less than or equal to 0.0040% of N, less than or equal to 0.0005% of B and the balance of Fe and inevitable impurities. According to the 110Ksi quenched and tempered steel for the coiled tubing, relative economic components are adopted for designing, on the basis of carbon, silicon and manganese, the design that multiple microalloy chemical components are added is adopted, and a quenched and tempered finished pipe has excellent strength and plasticity (the yield strength is larger than or equal to 770 MPa, the tensile strength is larger than or equal to 830 MPa, and the ductility is larger than or equal to 20%); and meanwhile, the alloy also has high low-temperature toughness, appropriate microhardness and excellent acid resistance (the impact energy at-40 DEG C is greater than or equal to 100J, the micro Vickers hardness HV10 is less than or equal to 300, and the KISSC is greater than or equal to 26.5), meets the requirements of various working conditions of the 110Ksi coiled tubing on the basis of effectively controlling the alloy cost, and is suitable for various well mine requirements.

Description

Technical Field

[0001] The present invention relates to a metal material and a manufacturing method thereof, in particular to a 110Ksi quenched and tempered coiled oil pipe steel, a steel pipe and a production method thereof. Background Art

[0002] Compared to conventional threaded tubing, coiled tubing (CT110) is a seamless, seamless tubing system made from several steel strips joined together at an angle, then rolled, formed, and welded. CT110 is widely used in oil and gas field workover, drilling, completion, and logging operations. With the development of oil and gas operations and advancements in drilling and completion technologies, the number of deep, high-pressure, and horizontal wells has increased, creating increasingly complex service environments. Conventional CT110 tubing is no longer suitable for these applications.

[0003] Current coiled tubing applications still primarily rely on conventional low-carbon alloy steel pipes, often containing high levels of manganese and precious alloys. This increases welding difficulty and hinders hardness control (the material has good hardenability, and uneven cooling can produce localized hard spots, affecting the material's forming and application performance). Furthermore, the microstructure of the weld seam of conventional coiled tubing after fabrication differs significantly from that of the pipe body, resulting in high residual stresses and increased susceptibility to corrosion at the weld, which is a common cause of field failures. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a 110Ksi quenched and tempered coiled tubing steel in response to the deficiencies in the above-mentioned prior art, which has excellent strength and plasticity as well as good low-temperature toughness and acid resistance.

[0005] The technical solution adopted by the present invention to solve the above-mentioned problems is:

[0006] A 110Ksi quenched and tempered coiled tubing steel has the following chemical compositions by weight: C 0.10%-0.20%, Si 0.16%-0.30%, Mn 0.75%-1.05%, P≤0.012%, S≤0.001%, Cu 0.20%-0.30%, Ni 0.10%-0.15%, Cr 0.52%-0.71%, Mo 0.03%-0.08%, Nb 0.010%-0.020%, Ti 0.010%-0.020%, Ca 0.0020%-0.0030%, Al 0.020%-0.030%, N≤0.0040%, B≤0.0005%, and the remainder being Fe and unavoidable impurities.

[0007] Furthermore, the weight percentage of C and Mn satisfies (C+Mn)×10 4Between 110 and 125; the weight percentage of Cr and Mo satisfies (Cr+Mo)×10 4 Between 55 and 85.

[0008] Further preferably, the chemical composition of the 110Ksi quenched and tempered coiled tubing steel is as follows, by weight percentage: C 0.11%-0.17%, Si 0.18%-0.25%, Mn 0.95%-1.05%, P≤0.012%, S≤0.001%, Cu 0.25%-0.30%, Ni 0.12%-0.15%, Cr 0.57%-0.69%, Mo 0.03%-0.08%, Nb 0.015%-0.018%, Ti 0.012%-0.015%, Ca 0.0023%-0.0028%, Al 0.021%-0.027%, N≤0.0040%, B≤0.0005%, and the remainder is Fe and unavoidable impurities.

[0009] More preferably, the weight percentage of C and Mn satisfies (C+Mn)×10 4 Between 110 and 120; the weight percentage of Cr and Mo satisfies (Cr+Mo)×10 4 Between 60 and 80.

[0010] The design concept of the present invention on chemical composition is as follows:

[0011] Carbon (C): The most economical interstitial solid solution strengthening element, it directly affects the basic strength properties of the material after quenching. Therefore, compared with the low-carbon composition design of existing conventional coiled tubing, the carbon content of the present invention is designed to be higher. However, excessive carbon content can lead to increased segregation and the occurrence of weld groove cracking defects. To balance strength and weld performance, the optimal carbon content of the present invention is 0.10% to 0.20%.

[0012] Silicon (Si): It is beneficial for assisting desulfurization and improving the material's corrosion resistance. However, excessive silicon content can cause severe tiger stripes on the surface and affect welding performance. The appropriate Si content in this invention is 0.16% to 0.30%.

[0013] Manganese (Mn): It can improve the hardenability of steel and significantly increase its yield and tensile strength. However, Mn is a segregating element, which is not conducive to improving the material's acidic service performance. Therefore, the appropriate addition amount of Mn in the present invention is 0.75% to 1.05%.

[0014] Chromium and molybdenum (Cr, Mo): can improve the hardenability of the material and increase the proportion of martensite during the quenching process. At the same time, because Cr and Mo can improve the tempering stability of the material, the corresponding expansion of the tempering process range can enable the material to meet the 110 grade requirements when tempered at higher temperatures. However, since Mo is a precious metal, excessive addition is not economical. The combined addition of Cr+Mo can further reduce the overall alloy cost while improving the tempering stability of the material. Therefore, the appropriate addition amount of Cr in the present invention is 0.52% to 0.71%, and the appropriate addition amount of Mo is 0.03% to 0.08%.

[0015] Copper and nickel (Cu, Ni): Cu promotes uniform corrosion in hydrochloric acid environments, while Ni is added to reduce the risk of copper embrittlement and provide corrosion resistance during service. Suitable additions for Cu are 0.20% to 0.30% and Ni is 0.10% to 0.15%.

[0016] Phosphorus and sulfur (P, S): P can promote the formation of hydrochloric acid corrosion passivation film, but too high a content can easily lead to central segregation and increased brittleness of the material. The appropriate P content is ≤0.012%. S can easily lead to the formation of Mn / S inclusions, which greatly increases the risk of hook cracks during high-frequency welding. At the same time, Mn / S inclusions in the matrix can act as a crack source and increase the risk of SSC cracking. Its content should be strictly limited, and the appropriate content should be ≤0.001%.

[0017] Niobium and titanium (Nb, Ti): Nb and Ti act as precipitation strengthening and grain refining elements, refining austenite grains and strengthening the material. Excessive additions can lead to excessive precipitates, affecting the material's acid resistance and impact toughness. Suitable additions for the present invention are 0.010% to 0.020% Nb and 0.010% to 0.020% Ti.

[0018] Calcium (Ca): Ca is added primarily to modify inclusions, initially forming small, discrete Ca oxides that serve as nucleation sites for inclusions, thereby refining the inclusions in the steel. Excessive Ca additions can lead to excessive oxide inclusions, affecting the material's acid resistance. The optimal addition level for this method is 0.0020% to 0.0030%.

[0019] Aluminum (Al): Al is added as a deoxidizer. Excessive addition will lead to excessive oxide inclusions in the steel, affecting the purity of the steel and detrimental to the material's acid resistance. The content of Al in the present invention is preferably controlled at 0.020% to 0.030%.

[0020] Nitrogen (N): Nitrogen reacts with Ti in steel to form TiN particles, which refines austenite grains. However, excessive N content can cause TiN particles to grow rapidly, affecting the toughness and acid resistance of the material. The content in the present invention is preferably controlled at ≤ 0.004%.

[0021] Boron (N): In the present invention, there is no need to add additional B to improve hardenability, and the residual B content in the steel due to the iron alloy is controlled to be ≤0.0005%.

[0022] In the quenched and tempered coiled tubing steel of the present invention, a certain amount of C+Mn is added, and (C+Mn)×10 4 The value of satisfies 110-125, ensuring the basic quenching strength of the material; by adding a certain amount of alloying elements such as Cr+Mo, on the one hand, the proportion of martensite after quenching is increased to obtain a higher basic quenching strength, and on the other hand, the tempering stability is improved, so that the material still meets the 110-level strength requirements after high-temperature tempering, while also having high toughness and plasticity; by adding a certain amount of Nb and Ti, the structure is refined to improve the acid resistance of the material. Moreover, the molten steel is treated with calcium to deform the inclusions and improve the acid resistance of the material. In addition, the present invention adds a certain amount of Cu and Ni to improve the overall corrosion resistance of the material, and adopts a low P and S design to reduce internal defects in the material and improve the overall service performance of the material. It should be noted that: in (C+Mn)×10 4 The value must meet the requirement of 110~125, and (Cr+Mo)×10 4 The value should be between 55 and 85, mainly considering the proportion of quenched martensite, high temperature tempering stability and manufacturing cost.

[0023] The present invention also provides a method for producing the above-mentioned 110Ksi quenched and tempered coiled tubing steel, comprising the following steps:

[0024] 1) Smelting and Casting: According to the composition of the 110Ksi quenched and tempered coiled tubing steel, converter smelting, off-furnace refining, and mold slag protection casting are performed to obtain slabs that meet the composition requirements;

[0025] 2) Slab heating: The slab is heated at 1260±30℃ for 150-180min to fully dissolve the alloy and homogenize the slab composition;

[0026] 3) Rolling: The heated slab is subjected to rough rolling and finish rolling to form 2.5-6 mm steel strips. During the rolling process, the rough rolling temperature is controlled at 1060±30°C and the finish rolling temperature is controlled at 850±30°C.

[0027] 4) Controlled cooling: After finishing rolling, the steel strip is cooled to 580-630°C at a cooling rate of >30°C / s and then coiled to obtain a steel coil;

[0028] 5) Pickling: After the steel coil cools to room temperature, it is sent down for pickling to remove the surface iron oxide scale;

[0029] 6) Tube making: The steel coil is made into coiled tubing of a certain size and length through a series of tube making processes according to the requirements, and the tubing is then rolled up on a disc;

[0030] 7) Whole pipe heat treatment: The whole coil of steel pipe is uncoiled and heat treated in the heat treatment production line. The specific process includes three steps: induction heating austenitization of the steel pipe, quenching and induction tempering. The austenitization temperature is controlled at 920-970℃, and the austenitization holding time is 60-90 seconds. After austenitization, it is quenched to room temperature at a quenching rate of ≥100℃ / s; the tempering temperature is controlled at 580-690℃, and the tempering time is 80-120 seconds. After tempering, it is air-cooled to within 180℃ and water-cooled to room temperature, and then coiled to obtain the final product.

[0031] According to the above scheme, in step 1), smelting is carried out in a converter, and the P content is precisely controlled within 0.012%; LF+RH double refining is adopted for refining outside the furnace, and the sulfur content of the steel is controlled within 0.001% by LF deep desulfurization, and the harmful gas oxygen content and inclusions in the molten steel are controlled by RH degassing and calcium treatment (calcium treatment is carried out by feeding silicon-calcium wire into the molten steel, and the input amount of silicon-calcium wire is 2-3 kg / t), wherein the O content is ≤0.0025%, inclusion A is level 0, and B and C inclusions are ≤level 1; a straight arc casting machine is used for protective slag casting, and the superheat is controlled within 25°C to avoid segregation of the slab during the casting process and improve the acid resistance of the material.

[0032] According to the above scheme, in step 2), the slab should be heated throughout the heating process in a reducing, negative oxygen atmosphere, with the oxygen content controlled within 0.2%. Heating should be performed at 1260±30°C for 140-180 minutes. This process not only achieves solid solution and composition homogenization of the alloy, but also controls the heating of the slab to avoid selective oxidation of the slab surface, which could lead to Cu precipitation at grain boundaries and affect the subsequent service life of the material.

[0033] According to the above scheme, in step 3), the rough rolling temperature is controlled at 1060±30°C and the finishing rolling temperature is controlled at 850±30°C. The purpose is to obtain a fine original structure, which is beneficial to improve the toughness of the material and resist the strength reduction caused by the Bauschinger effect during the subsequent rewinding process.

[0034] According to the above scheme, in step 4), after finish rolling, the steel is cooled to 580-630°C at a cooling rate of >30°C / s and then coiled to obtain a fine and uniform original structure, which is beneficial to the subsequent pipe making performance.

[0035] According to the above scheme, in step 7), the austenitizing temperature is controlled at 920-970°C, and the austenitizing holding time is 60-90 seconds to ensure that the structure is fully austenitized and avoid insufficient austenitization affecting the strength after quenching; the material is quenched to room temperature at a quenching cooling rate of ≥100°C / s, so that the proportion of martensite in the structure after quenching is ≥90% to ensure the basic strength after quenching; the tempering temperature is controlled at 580-690°C, and the tempering time is 80-120 seconds to ensure that the martensite structure after quenching is fully tempered, thereby improving the toughness and plasticity of the material while reducing the internal stress of the material structure and improving its acid resistance.

[0036] The 110Ksi quenched and tempered coiled tubing steel produced by the above method has a microstructure of tempered bainite + a small amount of bainite, wherein the proportion of bainite is less than 10%, the yield strength is ≥770MPa, the tensile strength is ≥830MPa, the elongation is ≥20%, the impact energy at ~40℃ is ≥100J, the micro Vickers hardness HV10 is ≤300, and the K ISSC ≥26.5.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] First, the present invention is designed by adding multiple microalloy chemical components based on carbon, silicon and manganese, especially in (C+Mn)×10 4 The range is 110~125 and at the same time (Cr+Mo)×10 4 The range of 55 to 85 is primarily based on considerations such as the quenched martensite ratio, high-temperature tempering stability, and cost. This ensures that the finished steel, after sufficient tempering, still meets the required 110 ksi strength while also maintaining high toughness and ductility. Furthermore, unlike conventional quenched and tempered steel, the chemical composition design of this invention eliminates the need for the addition of element B to enhance hardenability.

[0039] Secondly, the present invention adopts a relatively economical composition design to obtain 110Ksi quenched and tempered coiled tubing steel. The finished pipe not only has excellent strength and plasticity (yield strength ≥770MPa, tensile strength ≥830MPa, elongation ≥20%), but also has high low-temperature toughness (-40℃ impact energy ≥100J), appropriate microhardness (micro Vickers hardness HV10 ≤300) and excellent acid resistance (K ISSC ≥26.5), which can meet various operation requirements such as high pressure operation and acid environment operation.

[0040] Third, the present invention adopts an induction heating austenitizing + quenching + induction tempering process in the heat treatment and tempering process. Since the induction heating speed is faster than the traditional radiation heat transfer and heat conduction heat transfer, the material can be austenitized in a shorter time and the austenite grains can be refined to a certain extent. During the induction tempering process, due to the fast heating speed, the tempering treatment can be performed at a relatively higher tempering temperature. Uniform and fine carbides are precipitated in the structure, and substructures such as dislocations can be restored to a large extent, which is beneficial to improving the toughness and acid resistance of the material. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 and Figure 2 They are the organizational morphology diagrams of the base material and weld part of the present invention respectively. DETAILED DESCRIPTION

[0042] In order to better understand the present invention, the content of the present invention is further illustrated below in conjunction with examples, but the present invention is not limited to the following examples.

[0043] Each embodiment of the present invention is produced according to the following steps:

[0044] 1) Smelting and Casting: According to the composition of the 110Ksi quenched and tempered coiled tubing steel, converter smelting, external refining, and mold slag casting were performed to obtain slabs meeting the composition requirements, as shown in Table 1. The smelting raw materials were prepared by adding silicon-manganese alloy, ferromanganese alloy, ferroniobium alloy, ferrochromium alloy, etc. to molten iron to produce molten steel with the target composition.

[0045] Converter smelting precisely controls the P content within 0.012%. LF+RH double refining is used for off-furnace refining. LF deep desulfurization controls the sulfur content of the steel to within 0.001%. RH degassing and calcium treatment are used to control inclusions and harmful oxygen content in the steel. The vacuum degassing time is more than 5 minutes. During calcium treatment, calcium-silicon wire (calcium content of more than 95.0%) is fed into the molten steel at a rate of 2.5 kg / t. The O content in the molten steel is ≤0.0025%. Superheat is controlled within 25°C during the pouring process.

[0046] 2) Slab heating: The slab is heated at 1260±30℃ for 150-180min to fully dissolve the alloy and homogenize the slab composition. The slab should be heated in a reducing negative oxygen atmosphere with hydrogen as the main component, and the oxygen volume percentage should be controlled within 0.2%.

[0047] 3) Rolling: The heated slab is subjected to rough rolling and finish rolling to form a 2.5-6 mm steel strip, wherein the rough rolling temperature is controlled at 1060±30°C and the finish rolling temperature is controlled at 850±30°C;

[0048] 4) Controlled cooling: After finishing rolling, the steel strip is cooled to 580-630°C at a cooling rate of >30°C / s and then coiled to obtain a steel coil;

[0049] 5) Pickling: After the steel coil cools to room temperature, it is sent down for pickling to remove the surface iron oxide scale;

[0050] 6) Tubing: Steel coils are processed through a series of tubing steps to produce coiled tubing, which is then wound on a disc. The diameter of the coiled tubing is 48-61 mm and the length is 5,000-7,000 meters.

[0051] 7) Whole pipe heat treatment: The whole coil of steel pipe is uncoiled and heat treated in the heat treatment production line. The specific process includes three steps: induction heating austenitization of the steel pipe, quenching and induction tempering. The austenitization temperature is controlled at 920-970℃, and the austenitization holding time is 60-90 seconds. After austenitization, it is quenched to room temperature at a quenching rate of ≥100℃ / s. After quenching, the martensite proportion of the microstructure is ≥90%; the tempering temperature is controlled at 580-690℃, and the tempering time is 80-120 seconds. After tempering, it is air-cooled to within 180℃ and water-cooled to room temperature. It is then coiled to obtain the final product (oil pipe).

[0052] The production steps of Comparative Example 1 were carried out with reference to Chinese patent application CN113637925 A; the production steps of Comparative Example 2 were carried out with reference to Chinese patent application CN108018488 A.

[0053] Table 1 is a list of chemical compositions of various embodiments and comparative examples of the present invention.

[0054] Table 2 and Table 3 are the main process parameters and corresponding performance lists of the embodiments of the present invention and the comparative examples respectively. The test standards of mechanical properties (yield strength, tensile strength and elongation, as well as impact energy and steel grade) in Table 3 adopt ASTMA370, the test standard of hardness adopts ASTM E18, the acid resistance (critical stress field intensity factor K of steel) ISSC ) is tested in accordance with NACE TM 0177.

[0055] Table 1 Chemical composition list of various embodiments and comparative examples of the present invention (unit: wt%)

[0056]

[0057] Note: X in Table 1 represents (C+Mn)×10 4 ;Y represents (Cr+Mo)×10 4 .

[0058] Table 2 List of main process parameters of various embodiments of the present invention and comparative examples

[0059]

[0060]

[0061] Table 2 continues the list of main process parameters of various embodiments and comparative examples of the present invention

[0062]

[0063] Table 3 Performance data of various embodiments of the present invention and comparative examples

[0064]

[0065] The 110Ksi quenched and tempered coiled tubing steel prepared in Examples 1 to 5 was tested according to GB T 10561 2005 standard, and the inclusions A were level 0, and the inclusions B and C were ≤ level 1.

[0066] like Figure 1 As shown in the microstructure of the 110Ksi quenched and tempered coiled tubing steel (i.e., parent material) prepared by the present invention, the microstructure is tempered bainite + a small amount of bainite, wherein the volume proportion of the bainite structure is less than 10%. Figure 2 As shown, the microstructure of the weld of the 110Ksi quenched and tempered coiled tubing steel prepared by the present invention is shown in FIG. Figure 2 As shown, the tissue type is basically the same as that of the parent material.

[0067] As shown in Table 3, the present invention, based on a relatively economical alloy design, can produce quenched and tempered coiled tubing products that meet the 110 Ksi performance requirement over a wide tempering temperature range. These products exhibit both excellent strength, ductility, and toughness, as well as excellent acid resistance. Comparative Example 1, which utilizes a higher Mn content, is susceptible to segregation, affecting its acid resistance, and lacks low-temperature toughness and acid resistance data. Comparative Example 2, produced in a TMCP state, exhibits lower microstructure uniformity than the present invention, resulting in lower plasticity and toughness.

[0068] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this field, several improvements and changes can be made without departing from the creative concept of the present invention, which all fall within the scope of protection of the present invention.

Claims

1. A 110Ksi quenched and tempered coiled tubing steel, characterized in that: The chemical composition by weight percentage includes: C 0.10%~0.20%, Si 0.16%~0.30%, Mn 0.75%~1.05%, P≤0.012%, S≤0.001%, Cu 0.20%~0.30%, Ni 0.10%~0.15%, Cr 0.52%~0.71%, Mo 0.03%~0.08%, Nb 0.010%~0.020%, Ti 0.010%~0.020%, Ca 0.0020%~0.0030%, Al 0.020%~0.030%, N≤0.0040%, B≤0.0005%, and the rest is Fe and unavoidable impurities.

2. The 110Ksi quenched and tempered coiled tubing steel according to claim 1, characterized in that: The weight percentage of C and Mn satisfies (C+Mn)×10 4 Between 110 and 125; the weight percentage of Cr and Mo satisfies (Cr+Mo)×10 4 Between 55 and 85.

3. The 110Ksi quenched and tempered coiled tubing steel according to claim 1, characterized in that: The chemical composition is calculated by weight as follows: C 0.11% to 0.17%, Si 0.18% to 0.25%, Mn 0.95% to 1.05%, P ≤ 0.012%, S ≤ 0.001%, Cu 0.25% to 0.30%, Ni 0.12% to 0.15%, Cr 0.57% to 0.69%, Mo 0.03% to 0.08%, Nb 0.015% to 0.018%, Ti 0.012% to 0.015%, Ca 0.0023% to 0.0028%, Al 0.021% to 0.027%, N ≤ 0.0040%, B ≤ 0.0005%, and the rest are Fe and unavoidable impurities; and the weight percentages of C and Mn satisfy (C + Mn) × 10 4 Between 110 and 120; the weight percentage of Cr and Mo satisfies (Cr+Mo)×10 4 Between 60 and 80.

4. The 110Ksi quenched and tempered coiled tubing steel according to claim 1, characterized in that: The microstructure is tempered bainite and a small amount of bainite, of which the proportion of bainite is less than 10%; yield strength ≥770MPa, tensile strength ≥830MPa, elongation ≥20%, -40℃ impact energy ≥100J, micro Vickers hardness HV10 ≤300, K ISSC ≥26.

5.

5. The method for producing 110Ksi quenched and tempered coiled tubing steel according to any one of claims 1 to 4, characterized in that: The steps include: (1) Smelting and casting: After converter smelting, refining outside the furnace and pouring, slabs that meet the composition requirements are obtained; (2) Slab heating and rolling: The slab is heated to fully dissolve the alloy and homogenize the slab composition, and then rolled into steel strip; (3) Controlled cooling: After finishing rolling, the steel strip is cooled to 580-630°C at a cooling rate of >30°C / s and then coiled to obtain a steel coil; (4) Pickling and pipe making: The steel coil is pickled to remove the surface iron oxide scale, and then made into a continuous oil pipe, and the pipe is collected on a disc to obtain a whole coil of steel pipe; (5) Heat treatment of the whole pipe: After the whole coil of steel pipe is uncoiled, it is heat treated. The heat treatment process specifically includes three steps: induction heating austenitization of the steel pipe, quenching and tempering. Among them, the austenitization temperature is controlled at 920-970°C, and the austenitization holding time is 60-90 seconds; after austenitization, it is quenched to room temperature at a quenching cooling rate of ≥100°C / s; the tempering temperature is controlled at 580-690°C, and the tempering time is 80-120 seconds; after tempering, it is cooled to room temperature to obtain the 110Ksi quenched and tempered continuous oil pipe steel product.

6. The method for producing 110Ksi quenched and tempered coiled tubing steel according to any one of claims 1 to 4, characterized in that: The steps include: 1) Smelting and Casting: After converter smelting, refining outside the furnace and pouring, slabs that meet the composition requirements are obtained; 2) Slab heating: The slab is heated at 1230-1290°C for 150-180 minutes to fully dissolve the alloy and homogenize the slab composition; 3) Rolling: The heated slab is subjected to rough rolling and finish rolling to form 2.5-6 mm steel strips. During the rolling process, the rough rolling temperature is controlled at 1030-1090°C, and the finish rolling temperature is controlled at 820-880°C. 4) Controlled cooling: After finishing rolling, the steel strip is cooled to 580-630°C at a cooling rate of >30°C / s and then coiled to obtain a steel coil; 5) Pickling and pipe making: After the steel coil is cooled to room temperature, it is pickled to remove the surface oxide scale, and then made into a continuous tubing, and the tube is wound on a disc to obtain a whole coil of steel pipe; 6) Whole pipe heat treatment: After the coiled steel pipe is uncoiled, it is heat treated. The heat treatment process specifically includes three steps: induction heating austenitization of the steel pipe, quenching, and tempering. The austenitization temperature is controlled at 920-970°C, and the austenitization holding time is 60-90 seconds. After austenitization, the steel pipe is quenched to room temperature at a quenching rate of ≥100°C / s. The tempering temperature is controlled at 580-690°C, and the tempering time is 80-120 seconds. After tempering, the steel pipe is air-cooled to less than 180°C and then water-cooled to room temperature. The steel pipe is then coiled to obtain the 110Ksi quenched and tempered coiled tubing steel.

7. The method for producing 110Ksi quenched and tempered coiled tubing steel according to claim 6, characterized in that: In step 1), smelting is carried out in a converter, and the P content is controlled within 0.012%; LF+RH double refining is adopted for refining outside the furnace, and the sulfur content of the steel is controlled within 0.001% by LF deep desulfurization, and the harmful gas oxygen content in the molten steel and the inclusions in the steel are controlled by RH degassing and calcium treatment, and the O content is ≤0.0025%, the inclusion A is level 0, and the inclusions of type B and C are ≤level 1.

8. The method for producing 110Ksi quenched and tempered coiled tubing steel according to claim 6, characterized in that: In step 2), a reducing negative oxygen atmosphere is used during the entire heating process of the slab, wherein the oxygen content is controlled within 0.2%.

9. The method for producing 110Ksi quenched and tempered coiled tubing steel according to claim 6, characterized in that: In step 7), the steel is quenched to room temperature at a quenching rate of ≥100° C. / s, so that the proportion of martensite in the structure after quenching is ≥90%.

10. A steel pipe using the 110Ksi quenched and tempered steel for coiled tubing according to any one of claims 1 to 4.

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