CN111809113A - A rare earth-containing TC-50 steel grade oil pipe blank - Google Patents

Abstract

The invention provides a TC-50 steel grade petroleum pipe blank containing rare earth, which comprises the following chemical components in percentage by mass: 0.28 to 0.32 percent of C; 0.15 to 0.30 percent of Si; 1.45 to 1.60 percent of Mn; p is less than or equal to 0.018 percent; s is less than or equal to 0.008 percent; 0.15 to 0.25 percent of Cr; 0.015-0.040% of Al; ce 0.0005-0.0020%; ni is less than 0.10 percent; cu is less than 0.10 percent; the balance being Fe and impurities. A method for producing a TC-50 steel grade petroleum pipe blank containing rare earth produces the TC-50 steel grade petroleum pipe blank containing the rare earth, and a TC-50 steel grade petroleum casing pipe containing the rare earth is made of the TC-50 steel grade petroleum pipe blank containing the rare earth. A production method of a TC-50 steel grade petroleum casing containing rare earth produces the TC-50 steel grade petroleum casing containing rare earth. The invention has the beneficial effects that: high tensile strength, high yield strength and high transverse impact resistance.

Description

A rare earth-containing TC-50 steel grade oil pipe blank

technical field

The invention relates to the production of oil casing, in particular to a rare earth-containing TC-50 steel grade oil pipe blank.

Background technique

TC-50 steel grade oil casing is a high value-added product, usually used for medium-depth oil and gas wells about 3000 meters, and can also be used for heavy oil thermal recovery wells about 2000 meters, mainly as technical casing and surface casing use. With the continuous increase of oil and gas drilling and production efforts in various countries in the world, the J55 steel grade oil casing cannot meet the drilling and production needs, and the N80 steel grade oil casing has the disadvantage of high cost and is not economical.

Such as a kind of 80ksi steel grade straight seam welded oil casing steel disclosed in Chinese patent CN101376943A, which adopts C, Si, Mn, Al, Fe and other components to obtain coils with a yield strength of 600-645 MPa through a straight seam welding process, N80 petroleum casing with tensile strength of 550-560MPa and transverse impact of 65J-90J. The cost of the casing is high, which is not conducive to popularization and application.

For example, Chinese patent CN101328559A discloses a low yield strength petroleum casing, which uses C, Si, Mn, P, S, Al, Fe and other components. In addition, it also refines the crystal grains by adding RE components.

For example, Chinese patent CN108374121A discloses a production method of rare earth-containing C110 steel grade petroleum casing, by keeping soft blowing argon at the bottom after refining in LF furnace, feeding an appropriate amount of rare earth wire according to the addition amount of 0.02%. However, in this scheme, the tensile strength is insufficient, the yield strength is low, and the lateral impact is not enough to support the use scenario of TC-50 steel grade oil casing.

Such as Chinese patent CN201910196594.0 discloses a kind of petroleum casing and its preparation method, it adopts C, Si, Mn, P, S, V, Ti, Al, RE, residual Fe and other components, by adding a small amount in the basic component The rare earth composition greatly improves the plasticity of the steel grade. However, in this scheme, its tensile strength is insufficient, the yield strength is low, and the lateral impact is not enough to support the use scenario of TC-50 steel grade oil casing, which only provides J55 The solution for steel grade oil tube blanks.

In the design of oil casing with high transverse impact value, Chinese patent CN103436787A discloses that adding Ca removes impurities in the pipe, thereby increasing the transverse impact value. Although the lateral impact value of 200J/cm ² at 0°C has been obtained, it is necessary to add Ca as a cost, and 200 J/cm ² has far exceeded the technical requirement. For general formation structures, it is not necessary to spend the cost of adding Ca to add Ca. The lateral impact value is raised to such a high level as 200J/cm2.

Therefore, the market is in urgent need of a TC-50 steel grade oil pipe blank and sleeve with high tensile strength, high yield strength and high lateral impact resistance, which does not contain Mo, Nb, Ca, and contains less Cu and Ni. Tube and its production process.

SUMMARY OF THE INVENTION

In order to solve the above-mentioned technical problems, the present invention discloses a kind of rare earth-containing material that does not contain Mo, Nb, and Ca, and contains less Cu and Ni and is low in cost, and can have high tensile strength, high yield strength and high lateral impact resistance. TC-50 steel grade petroleum tube blank, casing, and production process thereof. The technical scheme of the present invention is implemented as follows:

A rare earth-containing TC-50 steel grade petroleum tube blank is characterized in that: no calcium element is added, the size of the transverse impact value is modulated by adjusting the Mn/C mass ratio, and the chemical composition is composed of the following mass percentage: C (0.28 -0.32wt%); Si (0.15-0.30wt%); Mn (1.45-1.60wt%); P≤0.018wt%; S≤0.008wt%; Cr (0.15-0.25wt%); Al (0.015-0.040 wt%); Ce (0.0005-0.0020wt%); Ni<0.10wt%; Cu<0.10wt%; the balance is Fe and impurities; the Mn/C mass ratio satisfies 79/16≤Mn/C≤157/30 .

Preferably, the rare earth-containing TC-50 steel grade petroleum pipe blank as above is characterized in that: it is composed of the following chemical components by mass percentage: C 0.28wt%; Si 0.16wt%; Mn 1.46wt%: P 0.013wt %; S0.005wt%; Cr0.17wt%; Al 0.038wt%; Ce 0.0011wt%; Ni 0.005wt%;

Preferably, the rare earth-containing TC-50 steel grade petroleum pipe blank as described above is characterized in that it is composed of the following chemical components by mass percentage: C 0.30wt%; Si 0.23wt%; Mn 1.57wt%: P 0.012wt %; S0.006wt%; Cr0.21wt%; Al 0.025wt%; Ce 0.0015wt%; Ni 0.005wt%;

Preferably, the rare earth-containing TC-50 steel grade petroleum pipe blank as described above is characterized in that it is composed of the following chemical components by mass percentage: C 0.32wt%; Si 0.28wt%; Mn 1.58wt%: P 0.016wt %; S0.005wt%; Cr0.23wt%; Al 0.017wt%; Ce 0.0018wt%; Ni 0.005wt%;

A method for producing a rare earth-containing TC-50 steel grade petroleum pipe blank, producing the rare earth-containing TC-50 steel grade petroleum pipe blank, characterized in that: S1: blast furnace molten iron pretreatment: the blast furnace After the molten iron is pretreated, the sulfur content of the blast furnace molten iron is less than 0.01wt%; the pretreatment process uses magnesium powder for pretreatment; S2: top-bottom double blowing converter smelting produces molten steel: the blast furnace molten iron is mixed with Into the top-bottom double-blowing converter, the scrap steel is added according to the mass ratio of the blast furnace molten iron to the scrap steel of 9:1; the smelting process of the top-bottom double-blowing converter adopts a single-slag process, and the final slag basicity is controlled at 3.0; tapping; Silicon manganese, ferromanganese and ferrochromium are used for deoxidation and alloying, and aluminum deoxidation process is used for final deoxidation; slag must be blocked during the tapping process, and slag must be removed if the slag blocking fails; during the tapping process, according to the molten steel and lime block 1: The mass ratio of 2 is added to the white ash block; S3: LF furnace refining: the molten steel is loaded into the ladle and put into the LF furnace station for refining; during the refining process of the LF furnace, argon is normally blown as required, and the Heating and heating are carried out by gradually increasing the heating rate from several to high numbers; slagging and desulfurization, composition adjustment and heating operations are performed according to the composition and temperature of molten steel in the converter, and white slag-making operations are added during the refining process; S4: Add rare earth alloys: keep the bottom soft Blow Ar, add the rare earth alloy, the rare earth alloy is Ce-Fe alloy; S5: VD vacuum treatment: in the VD vacuum treatment process, the deep vacuum degree is less than or equal to 0.10KPa, and the deep vacuum time is greater than or equal to 13 minutes; S6: adding silicon Calcium wire: and soft blowing argon for 10-12 minutes after adding; S7: continuous casting of round billet to produce casting billet: hoist the ladle on the ladle turntable for 5-machine 5-strand round billet continuous casting; In the casting process, the constant speed control of low pulling speed, electromagnetic stirring and the whole process of protection pouring are adopted; in the continuous casting process, the superheat degree of molten steel ΔT=25°C; S8: cut to length: straighten the slab , and then use flame to cut to length into tube blanks; S9: Slowly cool the tube blanks by stacking.

Preferably, it also includes S10: sampling the tube blank for low-magnification inspection, if the result of the sulfur print test does not exceed level 1.0, the low-magnification inspection is qualified.

A rare earth-containing TC-50 steel grade petroleum casing is characterized in that it is made by using the rare earth-containing TC-50 steel grade petroleum pipe blank.

A method for producing rare earth-containing TC-50 steel grade petroleum casing, producing the rare earth-containing TC-50 steel grade petroleum casing, characterized in that: S11: heating a tube blank: heating the pipe The billet is put into the annular heating furnace for heating; during the heating process, the temperature of the preheating stage I is controlled at 1000-1100 °C, the temperature of the preheating stage II is controlled at 1120-1230 °C, and the temperature of the heating stage I is controlled at 1000-1100 °C. 1220～1290℃, heating stage II is controlled at 1260～1300℃, soaking stage I is controlled at 1260～1300℃, soaking stage II is controlled at 1250～1290℃; S12: bacterial perforation; S13: continuous rolling described above The tube blank produces a seamless steel pipe; S14: Straightening operation: cooling the seamless steel pipe, and straightening when the temperature of the seamless steel pipe drops to 517°C; S15: Threading: aligning both ends of the seamless steel pipe Do threading.

Preferably, before S11, it also includes S11-0: hot tool quality control; the hot tool must be measured before use, and the roller table must be inspected and processed before rolling.

Preferably, between S15 and S14, S14-0 and S14-1 are further included; S14-0: measure the residual stress of the seamless steel pipe by the ring cutting method; S14-1: perform non-destructive testing on the seamless steel pipe Flaw detection and hydrostatic testing.

The rare earth-containing TC-50 steel grade petroleum pipe blank according to the present invention, the rare earth-containing TC-50 steel grade petroleum pipe blank according to the present invention, does not consider the addition of calcium, but directly considers the Mn/C mass ratio to modulate The size of the lateral impact value can meet the requirements of oil extraction and further reduce the cost of calcium addition. Since the mass ratio of Mn/C satisfies 79/16≤Mn/C≤157/30, it is possible to avoid the influence of excessive Mn/C on the transverse impact characteristics on the basis of ensuring the hardenability.

The rare earth-containing TC-50 steel grade petroleum tube blank according to the present invention contains no _MO , Nb, Ca, and less Cu and Ni, so the production cost is low.

To sum up, according to the present invention, the technical solutions of the present invention can solve the technical problems of insufficient tensile strength, low yield strength and low lateral impact in the prior art at a lower cost; implementing the technical solutions of the present invention can achieve Technical effect of high tensile strength, high yield strength and high transverse impact.

Description of drawings

In order to explain the embodiments of the present invention or the technical solutions in the prior art more clearly, the following briefly introduces the accompanying drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only It is an embodiment of the present invention. For those of ordinary skill in the art, other drawings can also be obtained according to these drawings without creative efforts.

FIG. 1 is an overall flow chart of a production method of a rare earth-containing TC-50 steel grade petroleum pipe blank and a rare earth-containing TC-50 steel grade petroleum casing.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

Those skilled in the art understand that in steel products of various steel grades, some chemical components are usually added to improve various properties of the steel.

For example, carbon (C), as the carbon content in the steel increases, its yield point and tensile strength increase, and its cold brittleness increases, while its ductility and impact properties decrease, and its weldability deteriorates.

Such as silicon (Si), which is added as a reducing and deoxidizing agent in the steelmaking process. Silicon increases the yield point and tensile strength, while increasing the amount of silicon reduces the weldability of the steel.

Such as manganese (Mn), as a deoxidizer and desulfurizer in the steelmaking process, manganese steel has sufficient toughness, high strength and high hardness, which improves the hardenability of the steel, improves the hot workability of the steel, and increases the yield point.

Such as phosphorus (P), which is destructive to steel, the content of P should be kept as low as possible.

Such as sulfur (S), which is destructive to steel, the content of S should be minimized.

Such as chromium (Cr), can significantly improve the strength, hardness and wear resistance of steel, improve the oxidation resistance and corrosion resistance of steel, but reduce ductility and toughness at the same time.

Such as nickel (Ni), can increase the strength of the steel, while maintaining good plasticity and toughness.

Such as copper (Cu), can increase the strength and toughness of the steel, but reduce the plasticity.

Such as aluminum (Al), as a deoxidizer in steelmaking, adding a small amount of aluminum to steel can refine grains and improve impact toughness, but at the same time, it will affect hot workability and weldability.

The addition of small amounts of lanthanum-cerium alloys such as cerium (Ce) to austenitic and austenitic-ferritic stainless steels can significantly improve forging properties.

However, if the content of these chemical components is high, it will affect other properties of the steel, and if the content is low, it will not have the desired effect. In the traditional pipe making process, it is generally believed that carbon (C) is the most effective element to improve the strength and hardenability, but in order to improve the impact performance of the casing, generally speaking, it is necessary to increase Mn/C as much as possible. In order to find the best balance, the research and development team of the present invention worked hard on public relations, and found that the traditional understanding was wrong. While increasing the content of Mn and C at the same time, as long as the mass ratio of them is kept at about 5:1 (specifically, the mass ratio of Mn/C satisfies 79/16≤Mn/C≤157/30), not only will the hardenability of the steel be improved It can be effectively improved, and the impact performance of the casing can also be improved, rather than the trade-off in the traditional understanding. Therefore, in the present application, the content of carbon can be increased to 0.32wt%, and the content of Mn can also be increased. Correspondingly, the impact performance of the casing is improved, and its transverse impact value at 0°C is ≥63J/cm ² . Therefore, the present invention not only overcomes the traditional technical prejudice, but also improves the technical effect of the product. On the other hand, in the present invention, since it does not contain _MO , Nb, Ca and contains less Cu and Ni, and at the same time does not use expensive rare earth elements such as La, it can still obtain at least the effect of using elements such as La and Re, and the cost is higher. low.

In a specific embodiment 1 of the present invention, the rare earth-containing TC-50 steel grade petroleum pipe blank is composed of chemical components in the following mass percentages: C (0.28-0.32 wt %); Si (0.15-0.30 wt %); Mn (1.45-1.60wt%); P≤0.018wt%; S≤0.008wt%; Cr (0.15-0.25wt%); Al (0.015-0.040wt%); Ce (0.0005-0.0020wt%); Ni<0.10 wt%; Cu<0.10wt%; the balance is Fe and impurities, wherein the Mn/C mass ratio satisfies 79/16≤Mn/C≤157/30.

In this specific embodiment, Si has the effect of deoxidation and can improve the strength at the same time, but in order to consider the impact performance requirements of the casing, its content is controlled between 0.15-0.30wt%; Mn has the effect of solid solution strengthening, It can expand the austenite region, reduce the transformation temperature of austenite to ferrite, and then refine the ferrite grains and improve the strength and toughness of the steel. However, if the content of Mn is too high, segregation will occur, so it is controlled at 1.45. -1.60wt%; Cr can improve the strength and hardenability of steel, and can form a passivation film on the steel surface, which has the ability to resist hydrogen sulfide corrosion and oxidation, so its content is set at Cr (0.15- 0.25wt%); P will cause microsegregation and easily lead to the formation of fiber cracks in quenched martensite, so it is controlled below 0.018wt%; the increase of S content will lead to hot brittleness of steel, in order to ensure that the casing has good the toughness, the content of S should be less than 0.008wt%, Al has good deoxidation ability and can refine austenite grains, so its content is controlled at (0.015-0.040wt%);

In a preferred embodiment 2, it is composed of the following chemical components by mass percentage: C 0.28wt%; Si0.16wt%; Mn 1.46wt%: P 0.013wt%; S 0.005wt%; Cr 0.17wt%; Al 0.038wt% %; Ce 0.0011wt%; Ni0.005wt%; Cu 0.005wt%; the balance is Fe and impurities.

In a preferred embodiment 3, it is composed of chemical components with the following mass percentages: C 0.30wt%; Si0.23wt%; Mn 1.57wt%: P 0.012wt%; S 0.006wt%; Cr 0.21wt%; Al 0.025wt% %; Ce 0.0015wt%; Ni0.005wt%; Cu 0.005wt%; the balance is Fe and impurities.

In a preferred embodiment 4, it is composed of the following chemical components by mass percentage: C 0.32wt%; Si0.28wt%; Mn 1.58wt%: P 0.016wt%; S 0.005wt%; Cr 0.23wt%; Al 0.017wt% %; Ce 0.0018wt%; Ni0.005wt%; Cu 0.005wt%; the balance is Fe and impurities.

In a specific embodiment, as shown in FIG. 1 , a method for producing a rare earth-containing TC-50 steel grade petroleum pipe blank, producing the rare earth-containing TC-50 steel grade petroleum pipe blank, includes: S1: blast furnace molten iron pretreatment: after the blast furnace molten iron has undergone the pretreatment, the blast furnace molten iron has a sulfur content of less than 0.01wt%; the pretreatment process uses magnesium powder for pretreatment, which can effectively reduce blast furnace Sulfur content of molten iron.

S2: molten steel produced by top-bottom double blowing converter smelting: the blast furnace molten iron is mixed into the top and bottom double-blowing converter, and the scrap is added according to the mass ratio of the blast furnace molten iron to the scrap steel of 9:1. It should be pointed out that in this In the invention, since the scrap steel with relatively few impurities is used as the raw material, the impurity elements in the molten steel can be effectively reduced compared with the complete use of the molten steel, and the cost can be saved. It only contains a small amount or even does not contain Cu and Ni, the production difficulty is small, and the production cost is low;

It should be emphasized that, in the present invention, the single-slag process is adopted in the smelting process of the top-bottom double blowing converter, and the final slag basicity is controlled at 3.0 (relatively, the traditional process is 3.2), which further reduces the content of Si and Al in the molten steel. content.

During tapping, silicon-manganese, ferromanganese and ferrochromium are used for deoxidation and alloying, and aluminum deoxidation is used for final deoxidation; slag must be blocked during the tapping process, and slag must be removed if the slag blocking fails; The white ash block is added in a mass ratio of 1:2;

S3: LF furnace refining: put the molten steel into the ladle and put it into the LF furnace station for refining; during the refining process of the LF furnace, argon is normally blown as required, and the method of gradually increasing the heating rate from the low level to the high level is adopted Carry out heating and heating; according to the composition and temperature of molten steel in the converter, carry out slagging desulfurization, composition adjustment and heating operation, and additional white slag making operation during the refining process;

S4: Add rare earth alloy: keep the bottom soft blowing Ar, add the rare earth alloy, the rare earth alloy is Ce-Fe alloy, the Ce element can improve the morphology of non-metallic inclusions, strengthen grain boundaries and refine grains, etc. effect, so as to achieve the effect of grain refinement strengthening and improving impact toughness;

S5: VD vacuum treatment: in the VD vacuum treatment process, the deep vacuum degree is less than or equal to 0.10KPa, and the deep vacuum time is greater than or equal to 13 minutes;

S6: Add silicon calcium wire: and blow argon softly for 10-12 minutes after adding;

S7: Round billet continuous casting to generate casting billets: the ladle is hoisted onto the ladle turntable for 5-machine 5-stream round billet continuous casting; in the continuous casting process, the constant speed control of low pulling speed, electromagnetic stirring and The whole casting process is protected; in the continuous casting process, the superheat degree of molten steel ΔT=25°C; it should be emphasized that in the present invention, by reducing the superheat degree, the equiaxed crystals and columnar crystals of the slab are improved, and the casting rate is improved. quality of blanks.

S8: Cut to length: straighten the casting billet, and then cut it into a tube billet by using flame to cut to length;

S9: Slowly cooling the tube blank by stacking, by increasing the tempering temperature and prolonging the heat preservation time, it is beneficial to the homogenization of the steel structure, and the stress is eliminated, thereby improving the mechanical properties of the steel.

In a preferred embodiment, it also includes S10: sampling the tube blank for low-magnification inspection, if the sulfur mark test result does not exceed level 1.0, the low-magnification inspection is qualified, indicating that the quality of the pipeline is qualified and can be used for pipe making.

In a specific embodiment, a rare earth-containing TC-50 steel grade petroleum casing is made by using the rare earth-containing TC-50 steel grade petroleum pipe blank.

In a specific embodiment, as shown in FIG. 1 , a method for producing a rare earth-containing TC-50 steel grade petroleum casing, which produces the rare earth-containing TC-50 steel grade petroleum casing, is characterized by: It includes: S11: heating the tube blank: putting the tube blank into the annular heating furnace for heating; in the heating process, the temperature of the preheating stage I is controlled at 1000-1100°C, and the temperature of the preheating stage II is controlled at 1000-1100 °C Controlled at 1120～1230℃, the temperature of the heating stage I is controlled at 1220～1290℃, the heating stage II is controlled at 1260～1300℃, the soaking stage I is controlled at 1260～1300℃, and the soaking stage II is controlled at 1250～1290℃ , it should be pointed out that in the heating process, with the different components of the tube blank, the overheating temperature is different. In the present invention, in order to ensure thorough heating, the temperature of each heating stage is set slightly higher, so that the billet has good rolling performance.

S12: bacterial perforation; S13: continuous rolling of the tube blank to produce a seamless steel pipe; S14: straightening operation: cooling the seamless steel pipe, and straightening when the temperature of the seamless steel pipe drops to 517°C; S15: Threading: Threading is performed on both ends of the seamless steel pipe, and after the processing is completed, it becomes a usable product.

In a preferred embodiment, S11-0 is further included before S11: hot tool quality control; the hot tool must be measured before use, and the roller table must be inspected and treated before rolling to avoid scratching the pipe wall.

In a preferred embodiment, between S15 and S14, S14-0 and S14-1 are further included; S14-0: the residual stress of the seamless steel pipe is measured by the circumcision method; S14-1: for all the The above-mentioned seamless steel pipe is subjected to non-destructive testing and hydraulic test. If the two test results are qualified, the quality of the pipe is qualified and can be used.

的管坯，然后将规格为

的管坯进行堆垛缓冷。将规格为

的管坯放入环形加热炉进行加热，连续检查并控制好环形加热炉的预热段、加热段、均热段等各段的温度，保证加热透彻均匀而不过热用微机对环形加热炉各段温度进行自动控制并自动记录。热工具在使用前必须测量，轧前必须检查、处理辊道，避免划伤管壁。将加热好的规格为

的管坯进行菌式穿孔、然后在

PQF轧管机组上进行连续轧制、然后在定径及其上制成规格为

的无缝钢管，每批进行一次热取样，检查几何尺寸。当无缝钢管的温度降到517℃时进行矫直，采用环切法测量无缝钢管的残余应力。对上述工艺生产的规格为

的无缝钢管先后进行无损探伤和水压试验，合格的无缝钢管在两端进行螺纹加工、即成为最终产品。Taking 90-ton blast furnace molten iron smelting as an example, the 90-ton blast furnace molten iron was pretreated with magnesium powder for desulfurization and deoxidation, so that the content of S element in the molten iron was reduced to below 0.010%; 90 tons of pretreated molten iron was mixed into 100-ton grade molten iron In the top-bottom double blowing converter, 10 tons of high-quality scrap steel is added, and then the single-slag process is used for smelting. The final slag basicity is controlled at 3.0, and silicon-manganese, ferromanganese and ferrochromium are used for deoxidation and alloying during tapping. The final deoxidation adopts an aluminum deoxidation process. The slag must be blocked during the tapping process. If the slag blocking fails, the slag must be removed. After the alloy is added during the tapping process, 200kg of lime blocks are added. Put the smelted molten steel into the ladle and enter the LF furnace station for refining: normally blow argon according to the requirements during refining, and use the method of gradually increasing the heating rate from low to high levels to heat up; according to the composition and temperature of the converter molten steel Slag making and desulfurization, composition adjustment and heating operation; white slag making operation is adopted, and additional alloys are added in the middle and late stages. After the refining in the LF furnace, the bottom should be kept softly blowing Ar, and a predetermined amount of rare earth alloy should be added. The rare earth alloy is a Ce-Fe alloy. Then, the refined molten steel is subjected to VD vacuum treatment: deep vacuum, air degree ≤ 0.10KPa, deep vacuum time ≥ 13 minutes; then feed a certain length of silicon calcium wire, and keep 10 to 12 minutes after feeding the wire to blow Ar softly. The molten steel ladle after VD vacuum treatment is hung on the ladle turntable for 5-machine 5-strand round billet continuous casting. During continuous casting, constant speed control of low pulling speed, electromagnetic stirring and whole-process protection pouring process are adopted; molten steel superheat ΔT= 25°C; straightening the billet after exiting the secondary cooling area, and then cutting it to a size of

the tube blank, then the specification is

The tube blanks are stacked and cooled slowly. set the specification to

The preheating section, heating section, soaking section and other sections of the annular heating furnace are continuously inspected and controlled to ensure that the heating is thorough and even without overheating. Section temperature is automatically controlled and recorded. The hot tool must be measured before use, and the roller table must be inspected and treated before rolling to avoid scratching the pipe wall. The heated specification is

The tube blank is subjected to bacterial perforation, and then

Continuous rolling is carried out on the PQF pipe rolling mill, and then the sizing and the specifications are made into

For seamless steel pipes, one thermal sampling per batch is carried out to check the geometric dimensions. When the temperature of the seamless steel pipe drops to 517℃, it is straightened, and the residual stress of the seamless steel pipe is measured by the ring cutting method. The specifications produced by the above process are

The seamless steel pipe has been subjected to non-destructive testing and hydraulic test successively, and the qualified seamless steel pipe is thread-processed at both ends, which becomes the final product.

Through the aforementioned process, the test results of the chemical composition of the tube blanks formed by the preferred embodiments 2, 3, and 4 are shown in Table 1, and the mechanical properties of the seamless steel pipes prepared by using the embodiments 2, 3, and 4 are shown in Table 2. The mechanical properties of the seamless steel pipes prepared in Examples 2, 3 and 4 are shown in Table 3.

Table 1 Test results of chemical composition of tube blank (mass %)

C Si Mn P S Cr Al RE Ni Cu Example 2 0.28 0.16 1.46 0.013 0.005 0.17 0.038 0.0011 0.005 0.005 Example 3 0.30 0.23 1.57 0.012 0.006 0.21 0.025 0.0015 0.005 0.005 Example 4 0.32 0.28 1.58 0.016 0.005 0.23 0.017 0.0018 0.005 0.005

Table 2 Testing results of mechanical properties of seamless steel pipes

R_t0.5(MPa) R_m(MPa) R_t0.5/R_m A(%) a_KV(0℃,transverse,J/cm²) Residual Stress Example 2 462 663 0.70 25.0 95 21MPa Example 3 471 681 0.69 24.0 75 23MPa Example 4 495 712 0.70 22.0 63 25MPa

Table 3 Test results of metallographic properties of seamless steel pipes (grade)

It can be seen from the above test results that, in the present invention, since the mass ratio of Mn/C is set to satisfy 79/16≤Mn/C≤157/30, it is more efficient than the traditional J55 steel grade or N80 steel grade petroleum tube blank. In other words, the carbon content of up to 0.032 wt % can be achieved, and at the same time, the manganese content can be made to reach 1.58 wt %, and the hardenability and impact resistance of the steel can achieve ideal effects. Therefore, Examples 2, 3, and 4 all have good lateral impact with high carbon content and low Mn/C, which is contrary to the traditional perception that Mn/C must be improved as much as possible. The original technical bias has been eliminated, and considerable technical effects have been achieved. And we found that it is not that the smaller the Mn/C, the better the lateral impact value, but the need to satisfy 79/16≤Mn/C≤157/30, within this range, we found the best point of 73/14 in Example 2 , and obtained a transverse impact value close to 100J/cm ² , which fully meets the requirements of oil production. At the same time, on the premise that the present invention does not contain elements such as La and Re, the technical effect can be achieved not less than even in the case of adding La or Re elements.

It should be pointed out that the above are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be Included in the protection scope of the present invention.

Claims (10)

1. a rare earth-containing TC-50 steel grade petroleum tube blank, is characterized in that: do not add calcium element, modulate the size of transverse impact value by adjusting Mn/C mass ratio, be made up of the chemical composition of lower mass percentage: C 0.28-0.32wt%; Si0.15-0.30wt%; Mn 1.45-1.60wt%; P≤0.018wt%; S≤0.008wt%; Cr 0.15-0.25wt%; Al0.015-0.040wt%; Ce 0.0005 -0.0020wt%; Ni<0.10wt%; Cu<0.10wt%; the balance is Fe and impurities; the Mn/C mass ratio satisfies 79/16≤Mn/C≤157/30. 2. The rare earth-containing TC-50 steel grade petroleum tube blank according to claim 1, characterized in that: it is composed of chemical components of the following mass percentages: C 0.28wt%; Si 0.16wt%; Mn 1.46wt%: P 0.013wt%; S 0.005wt%; Cr 0.17wt%; Al 0.038wt%; Ce 0.0011wt%; Ni 0.005wt%; 3. A kind of rare earth-containing TC-50 steel grade petroleum tube blank according to claim 1, characterized in that: it is composed of the following chemical components by mass percentage: C 0.30wt%; Si 0.23wt%; Mn 1.57wt%: P 0.012wt%; S 0.006wt%; Cr 0.21wt%; Al 0.025wt%; Ce 0.0015wt%; Ni 0.005wt%; 4. The rare earth-containing TC-50 steel grade petroleum tube blank according to claim 1, characterized in that: it is composed of chemical components of the following mass percentages: C 0.32wt%; Si 0.28wt%; Mn 1.58wt%: P 0.016wt%; S 0.005wt%; Cr 0.23wt%; Al 0.017wt%; Ce 0.0018wt%; Ni 0.005wt%; 5. a production method of a rare earth-containing TC-50 steel grade oil pipe blank, producing a rare earth-containing TC-50 steel grade oil pipe blank described in any of claims 1-4, characterized in that: comprising: S1: blast furnace molten iron pretreatment: after the blast furnace molten iron is subjected to the pretreatment, the sulfur content of the blast furnace molten iron is less than 0.01%; the pretreatment process uses magnesium powder for pretreatment; S2: molten steel produced by smelting in the top-bottom double-blowing converter: mixing the blast furnace molten iron into the top-bottom double-blowing converter, and adding the scrap according to the mass ratio of the blast furnace molten iron to the scrap steel of 9:1; the top-bottom double-blowing converter The smelting process adopts the single-slag process, and the final slag basicity is controlled at 3.0; During tapping, silicon-manganese, ferromanganese and ferrochromium are used for deoxidation and alloying, and aluminum deoxidation is used for final deoxidation; slag must be blocked during the tapping process, and slag must be removed if the slag blocking fails; The white ash block is added in a mass ratio of 1:2; S3: LF furnace refining: put the molten steel into the ladle and put it into the LF furnace station for refining; during the refining process of the LF furnace, argon is normally blown as required, and the method of gradually increasing the heating rate from the low level to the high level is adopted Heating and heating up; additional white slag making operation in the refining process; S4: Add rare earth alloy: keep soft blowing of Ar at the bottom, add the rare earth alloy, and the rare earth alloy is Ce-Fe alloy; S5: VD vacuum treatment: in the VD vacuum treatment process, the deep vacuum degree is less than or equal to 0.10KPa, and the deep vacuum time is greater than or equal to 13 minutes; S6: Add silicon calcium wire, and blow argon softly for 10-12 minutes after adding; S7: Round billet continuous casting to generate cast billets: the ladle is hoisted onto the ladle turntable for 5-machine 5-stream round billet continuous casting; in the continuous casting process, the constant speed control of low pulling speed, electromagnetic stirring and The whole casting process is protected; in the continuous casting process, the superheat degree of molten steel ΔT=25°C; S8: Cut to length: straighten the casting billet, and then cut it into a tube billet by using flame to cut to length; S9: The tube blanks are slowly cooled by stacking. 6. the production method of a kind of rare earth-containing TC-50 steel grade petroleum tube blank according to claim 5, is characterized in that: It also includes S10: the tube blank is sampled for low magnification inspection, and if the result of the sulfur print test does not exceed level 1.0, the low magnification inspection is qualified. 7. A rare earth-containing TC-50 steel grade petroleum casing, characterized in that it is made by using a rare earth-containing TC-50 steel grade petroleum pipe blank described in any one of claims 1-4. 8. a production method of a rare earth-containing TC-50 steel grade petroleum casing, producing a rare earth-containing TC-50 steel grade petroleum casing according to claim 7, characterized in that: comprising: S11: Tube blank heating: Put the tube blank into an annular heating furnace for heating; during the heating process, the temperature of the preheating stage I is controlled at 1000-1100 °C, and the temperature of the preheating stage II is controlled at 1120-1120 °C. 1230°C, the temperature of the heating stage I is controlled at 1220-1290°C, the heating stage II is controlled at 1260-1300°C, the soaking stage I is controlled at 1260-1300°C, and the soaking stage II is controlled at 1250-1290°C. S12: bacterial perforation; S13: Continuously rolling the tube blank to produce a seamless steel tube; S14: Straightening operation: cooling the seamless steel pipe, and straightening when the temperature of the seamless steel pipe drops to 517°C; S15: Threading: Threading is performed on both ends of the seamless steel pipe. 9 . The method for producing a rare earth-containing TC-50 steel grade petroleum casing according to claim 8 , wherein: before S11, it also includes S11-0: quality control of thermal tools; before the thermal tools are used It must be measured, and the roller table must be inspected and treated before rolling. 10. The method for producing a rare earth-containing TC-50 steel grade petroleum casing according to claim 8, characterized in that: between S15 and S14, it also includes S14-0 and S14-1; S14-0: The residual stress of the seamless steel pipe is measured by the ring cutting method; S14-1: Perform non-destructive testing and hydrostatic test on the seamless steel pipe.

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