High-strength seamless steel tube

Abstract

The invention relates to the technical field of steel pipes, and provides a high-strength seamless steel pipe which comprises a base body and a reinforcing phase, and the base body is composed of, by weight, 0.16%-0.18% of carbon, 0.30%-0.36% of silicon, 1.2%-1.6% of manganese, 0.2%-0.4% of aluminum, 0.4%-2.5% of chromium, 0.04%-0.09% of copper, 1.0%-2.6% of molybdenum, 0.0035%-0.015% of phosphorus, 0.009%-0.013% of sulfur and the balance iron and inevitable impurities; the reinforcing phase comprises vanadium carbide, and the mass ratio of the reinforcing phase to the matrix is (1.5-3.5): 100. Through the technical scheme, the problem of poor tensile strength of the seamless steel pipe in the prior art is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of steel pipes, and in particular to a high-strength seamless steel pipe. Background Art

[0002] With the rapid development of modern industry, various industries have increasingly higher requirements for pipe performance. Oil and gas extraction operations often face extreme environments of high temperature, high pressure and strong corrosion. Ordinary steel pipes are easily damaged under such conditions and are difficult to meet actual needs. This severe challenge has led to the birth of high-strength seamless steel pipes, which ensure the safe and efficient transportation of oil and gas resources with excellent performance. Especially in the frontier field of deep-sea oil and gas extraction, high-strength seamless steel pipes play a vital role with their high-pressure resistance and have become an indispensable basic material. The automobile manufacturing industry is also constantly moving forward on the road of pursuing lightweight structure and enhanced strength. High-strength seamless steel pipes are widely used in the manufacture of key components. In the field of energy and power, supercritical and ultra-supercritical units of thermal power plants have extremely stringent requirements on the high-temperature creep resistance and steam oxidation corrosion resistance of pipes. With its excellent performance, high-strength seamless steel pipes stably carry the task of transporting high-temperature and high-pressure steam, laying a solid foundation for the reliable operation of power generation equipment.

[0003] Driven by the continuous breakthrough and innovation of R&D and manufacturing technologies, the increasingly stringent material standards in the industrial field have put forward higher requirements on the performance of high-strength seamless steel pipes. However, the existing seamless steel pipes have poor tensile strength and cannot meet the existing needs. Therefore, it is very important to develop a high-strength seamless steel pipe. Summary of the invention

[0004] The invention provides a high-strength seamless steel pipe, which solves the problem of poor tensile strength of the seamless steel pipe in the related art.

[0005] The technical solution of the present invention is as follows: The present invention provides a high-strength seamless steel pipe, comprising a matrix and a reinforcement phase, wherein the matrix is ​​composed of the following elements in percentage by weight: 0.16% to 0.18% carbon, 0.30% to 0.36% silicon, 1.2% to 1.6% manganese, 0.2% to 0.4% aluminum, 0.4% to 2.5% chromium, 0.04% to 0.09% copper, 1.0% to 2.6% molybdenum, 0.0035% to 0.015% phosphorus, 0.009% to 0.013% sulfur, and the remainder is iron and unavoidable impurities; The reinforcement phase includes vanadium carbide, and the mass ratio of the reinforcement phase to the matrix is ​​1.5-3.5:100.

[0006] As a further technical solution, the mass ratio of the chromium to the molybdenum is 0.5~1.5:1.

[0007] The present invention further improves the tensile strength of the seamless steel pipe by adjusting the mass ratio of chromium to molybdenum to 0.5-1.5:1.

[0008] As a further technical solution, the mass ratio of the chromium to the molybdenum is 1:1.

[0009] The present invention further improves the tensile strength of the seamless steel pipe by adjusting the mass ratio of chromium to molybdenum to 1:1.

[0010] As a further technical solution, the vanadium carbide is nickel-modified vanadium carbide, and its preparation process includes the following steps: ball-milling nano nickel powder and vanadium carbide powder, and calcining to obtain nickel-modified vanadium carbide.

[0011] The invention further improves the tensile strength of the seamless steel pipe by modifying the vanadium carbide powder with nano nickel powder.

[0012] As a further technical solution, the particle size of the nano nickel powder is 50-100 nm, and the particle size of the vanadium carbide powder is 20-40 μm.

[0013] As a further technical solution, the mass ratio of the nano nickel powder to the vanadium carbide powder is 1-3:100.

[0014] The present invention further improves the tensile strength of the seamless steel pipe by adjusting the mass ratio of nano nickel powder to vanadium carbide powder to 1-3:100.

[0015] As a further technical solution, the mass ratio of the nano nickel powder to the vanadium carbide powder is 1:50.

[0016] The present invention further improves the tensile strength of the seamless steel pipe by adjusting the mass ratio of nano nickel powder to vanadium carbide powder to 1:50.

[0017] As a further technical solution, the calcination temperature is 560-650° C. and the calcination time is 1-2 hours.

[0018] The present invention also proposes a method for preparing a high-strength seamless steel pipe, comprising the following steps: S1, preparing materials according to the element composition of the matrix, adding the reinforcing phase after smelting, stirring and mixing, and casting to obtain a round steel billet; S2, performing piercing and rolling on the round steel billet to obtain a hollow tube billet; S3, cooling the hollow tube blank to 500°C-600°C and keeping the temperature for 1-3 hours to obtain a heat-treated hollow tube blank; S4, quenching and cooling the heat-treated hollow tube to room temperature to obtain a room-temperature hollow tube; S5, heating the room temperature hollow tube to 500-650°C and keeping the temperature for 0.5-1.5h to obtain a high strength seamless steel tube. As a further technical solution, the rolling temperature is 950-1050°C.

[0019] The working principle and beneficial effects of the present invention are: In the present invention, the seamless steel pipe includes a matrix and a reinforcement phase. In the element composition of the matrix, the proportion of chromium and molybdenum is increased, thereby improving the tensile strength of the seamless steel pipe; adding vanadium carbide as a reinforcement phase significantly improves the tensile strength of the seamless steel pipe, thereby solving the problem of poor tensile strength of existing seamless steel pipes. DETAILED DESCRIPTION

[0020] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. 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.

[0021] In the following embodiments and comparative examples, the carbon in the matrix elements of the seamless steel pipe comes from an iron-carbon alloy containing 4wt% carbon, silicon comes from a ferrosilicon alloy containing 20wt% silicon, manganese comes from a ferromanganese alloy containing 65wt% manganese, aluminum comes from an aluminum-iron alloy containing 15wt% aluminum, chromium comes from a ferrochrome alloy containing 55wt% chromium, copper comes from a copper-iron alloy containing 70wt% copper, molybdenum comes from a ferromolybdenum alloy containing 55wt% molybdenum, the purity of the vanadium carbide powder is 99.9wt% and the particle size is 20μm, and the purity of the nano-nickel powder is 99wt% and the particle size is 80nm.

[0022] Example 1 A high-strength seamless steel pipe comprises a matrix and a reinforcement phase, wherein the matrix is ​​composed of the following elements in percentage by weight: 0.18% carbon, 0.36% silicon, 1.6% manganese, 0.4% aluminum, 0.4% chromium, 0.09% copper, 2.6% molybdenum, 0.015% phosphorus, 0.013% sulfur, and the balance is iron and unavoidable impurities; The reinforcement phase includes vanadium carbide, and the mass ratio of the reinforcement phase to the matrix is ​​3.5:100; The preparation method thereof comprises the following steps: S1. The ingredients are prepared according to the element composition of the matrix, the reinforcing phase is added after smelting, the mixture is stirred and mixed, and the round steel billet is cast; S2, piercing and rolling the round steel billet at a rolling temperature of 1050° C. to obtain a hollow tube billet; S3, cooling the hollow tube blank to 600°C and keeping the temperature for 1 hour to obtain a heat-treated hollow tube blank; S4, the heat-treated hollow tube is quenched and cooled to room temperature to obtain a room temperature hollow tube; S5. Heat the room temperature hollow tube to 650°C and keep it warm for 0.5h to obtain a high-strength seamless steel tube.

[0023] Example 2 A high-strength seamless steel pipe comprises a matrix and a reinforcement phase, wherein the matrix is ​​composed of the following elements in weight percentage: 0.16% carbon, 0.30% silicon, 1.2% manganese, 0.2% aluminum, 2.5% chromium, 0.04% copper, 1.0% molybdenum, 0.0035% phosphorus, 0.009% sulfur, and the balance is iron and unavoidable impurities; The reinforcement phase includes vanadium carbide, and the mass ratio of the reinforcement phase to the matrix is ​​1.5:100; The preparation method thereof comprises the following steps: S1. The ingredients are prepared according to the element composition of the matrix, the reinforcing phase is added after smelting, the mixture is stirred and mixed, and the round steel billet is cast; S2, piercing and rolling the round steel billet at a rolling temperature of 950° C. to obtain a hollow tube billet; S3, cooling the hollow tube to 500°C and keeping it at this temperature for 3 hours to obtain a heat-treated hollow tube; S4, the heat-treated hollow tube is quenched and cooled to room temperature to obtain a room temperature hollow tube; S5. Heat the room temperature hollow tube to 500°C and keep it warm for 1.5 hours to obtain a high-strength seamless steel tube.

[0024] Example 3 A high-strength seamless steel pipe, characterized in that it comprises a matrix and a reinforcement phase, wherein the matrix is ​​composed of the following elements in weight percentage: 0.17% carbon, 0.33% silicon, 1.4% manganese, 0.3% aluminum, 1.9% chromium, 0.06% copper, 1.1% molybdenum, 0.0085% phosphorus, 0.01% sulfur, and the balance is iron and unavoidable impurities; The reinforcement phase includes vanadium carbide, and the mass ratio of the reinforcement phase to the matrix is ​​2.5:100.

[0025] The preparation method thereof comprises the following steps: S1. The ingredients are prepared according to the element composition of the matrix, the reinforcing phase is added after smelting, the mixture is stirred and mixed, and the round steel billet is cast; S2, piercing and rolling the round steel billet at a rolling temperature of 1000° C. to obtain a hollow tube billet; S3, cooling the hollow tube to 550°C and keeping the temperature for 2 hours to obtain a heat-treated hollow tube; S4, the heat-treated hollow tube is quenched and cooled to room temperature to obtain a room temperature hollow tube; S5. Heat the room temperature hollow tube to 580°C and keep it warm for 1 hour to obtain a high-strength seamless steel tube.

[0026] Example 4 The only difference between this embodiment and embodiment 3 is that the matrix of this embodiment is composed of the following elements in weight percentage: 0.17% carbon, 0.33% silicon, 1.4% manganese, 0.3% aluminum, 0.6% chromium, 0.06% copper, 2.4% molybdenum, 0.0085% phosphorus, 0.01% sulfur, and the remainder is iron and unavoidable impurities.

[0027] Example 5 The only difference between this embodiment and embodiment 3 is that the matrix of this embodiment is composed of the following elements in weight percentage: 0.17% carbon, 0.33% silicon, 1.4% manganese, 0.3% aluminum, 1.0% chromium, 0.06% copper, 2.0% molybdenum, 0.0085% phosphorus, 0.01% sulfur, and the remainder is iron and unavoidable impurities.

[0028] Example 6 The only difference between this embodiment and embodiment 3 is that the matrix of this embodiment is composed of the following elements in weight percentage: 0.17% carbon, 0.33% silicon, 1.4% manganese, 0.3% aluminum, 1.5% chromium, 0.06% copper, 1.5% molybdenum, 0.0085% phosphorus, 0.01% sulfur, and the remainder is iron and unavoidable impurities.

[0029] Example 7 The only difference between this embodiment and embodiment 3 is that the matrix of this embodiment is composed of the following elements in weight percentage: 0.17% carbon, 0.33% silicon, 1.4% manganese, 0.3% aluminum, 1.8% chromium, 0.06% copper, 1.2% molybdenum, 0.0085% phosphorus, 0.01% sulfur, and the remainder is iron and unavoidable impurities.

[0030] Example 8 The difference between this embodiment and embodiment 6 is that the reinforcing phase of this embodiment includes modified vanadium carbide, and the preparation process of modified vanadium carbide includes the following steps: ball milling nano nickel powder and vanadium carbide micro powder, calcining to obtain nickel modified vanadium carbide. The mass ratio of nano nickel powder to vanadium carbide micro powder is 1:100, the calcination temperature is 600°C, and the time is 1.5h.

[0031] Example 9 The difference between this embodiment and embodiment 6 is that the reinforcing phase of this embodiment includes modified vanadium carbide, and the preparation process of modified vanadium carbide includes the following steps: ball milling nano nickel powder and vanadium carbide micro powder, calcining to obtain nickel modified vanadium carbide. The mass ratio of nano nickel powder to vanadium carbide micro powder is 1:50, the calcination temperature is 600° C., and the time is 1.5 hours.

[0032] Example 10 The difference between this embodiment and embodiment 6 is that the reinforcing phase of this embodiment includes modified vanadium carbide, and the preparation process of modified vanadium carbide includes the following steps: ball milling nano nickel powder and vanadium carbide micro powder, calcining to obtain nickel modified vanadium carbide. The mass ratio of nano nickel powder to vanadium carbide micro powder is 3:100, the calcination temperature is 600°C, and the time is 1.5h.

[0033] Comparative Example 1 The difference between this comparative example and Example 2 is that the matrix of this comparative example is composed of the following elements in weight percentage: 0.16% carbon, 0.30% silicon, 1.2% manganese, 0.2% aluminum, 3.5% chromium, 0.04% copper, 0.0035% phosphorus, 0.009% sulfur, and the balance is iron and unavoidable impurities; The reinforcement phase includes vanadium carbide, and the mass ratio of the reinforcement phase to the matrix is ​​3.5:100.

[0034] Comparative Example 2 The only difference between this comparative example and Example 2 is that the matrix of this comparative example is composed of the following elements in weight percentage: 0.16% carbon, 0.30% silicon, 1.2% manganese, 0.2% aluminum, 0.04% copper, 3.5% molybdenum, 0.0035% phosphorus, 0.009% sulfur, and the balance is iron and unavoidable impurities.

[0035] Comparative Example 3 The only difference between this comparative example and Example 2 is that the matrix of this comparative example is composed of the following elements in weight percentage: 0.16% carbon, 0.30% silicon, 1.2% manganese, 0.2% aluminum, 0.04% copper, 0.0035% phosphorus, 0.009% sulfur, and the balance is iron and unavoidable impurities.

[0036] Comparative Example 4 The only difference between this comparative example and Example 2 is that the matrix of this comparative example is composed of the following elements in weight percentage: 0.16% carbon, 0.30% silicon, 1.2% manganese, 0.2% aluminum, 0.04% copper, 0.0035% phosphorus, 0.009% sulfur, and the balance is iron and unavoidable impurities; there is no reinforcing phase.

[0037] The high-strength seamless steel pipes prepared in Examples 1 to 10 and Comparative Examples 1 to 4 were subjected to tensile tests according to GB / T 228.1-2021 "Tensile Tests for Metallic Materials Part 1: Room Temperature Test Methods" to test the room temperature tensile strength of the steel pipes. The measured data are shown in Table 1.

[0038] Table 1 Test results of tensile strength of seamless steel pipe

[0039] Comparing Example 2 with Comparative Examples 1 to 3, it is explained that in the present invention, chromium and molybdenum are added to the matrix at the same time, and the two act synergistically to improve the tensile strength of the seamless steel pipe. Comparing Example 2 with Comparative Example 4, it is explained that the addition of vanadium carbide as a reinforcing phase in the present invention improves the tensile strength of the seamless steel pipe. Comparing Examples 3 to 4 with Examples 5 to 7, it is explained that the mass ratio of chromium to molybdenum in the matrix is ​​adjusted to 0.5 to 1.5:1 in the present invention, which further improves the tensile strength of the seamless steel pipe. Comparing Example 6 with Examples 5 and 7, it is explained that when the mass ratio of chromium to molybdenum in the matrix is ​​adjusted to 1:1 in the present invention, the tensile strength of the seamless steel pipe is best. Comparing Examples 8 to 10 with Example 6, it is explained that the present invention uses nano-nickel powder to modify vanadium carbide, which further improves the tensile strength of the seamless steel pipe. Comparing Example 9 with Example 8 and Example 10, it is explained that when the mass ratio of nano-nickel powder to vanadium carbide in the modified vanadium carbide raw material prepared by the present invention is 1:50, the tensile strength of the seamless steel pipe is best.

[0040] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A high-strength seamless steel pipe, characterized in that: The invention comprises a matrix and a reinforcement phase, wherein the matrix is ​​composed of the following elements in weight percentage: 0.16% to 0.18% carbon, 0.30% to 0.36% silicon, 1.2% to 1.6% manganese, 0.2% to 0.4% aluminum, 0.4% to 2.5% chromium, 0.04% to 0.09% copper, 1.0% to 2.6% molybdenum, 0.0035% to 0.015% phosphorus, 0.009% to 0.013% sulfur, and the balance is iron and unavoidable impurities; The reinforcement phase includes vanadium carbide, and the mass ratio of the reinforcement phase to the matrix is ​​1.5-3.5:

100.

2. A high-strength seamless steel pipe according to claim 1, characterized in that: The mass ratio of the chromium to the molybdenum is 0.5-1.5:

1.

3. A high-strength seamless steel pipe according to claim 2, characterized in that: The mass ratio of the chromium to the molybdenum is 1:

1.

4. A high-strength seamless steel pipe according to claim 1, characterized in that: The vanadium carbide is nickel-modified vanadium carbide. The preparation process of the nickel-modified vanadium carbide comprises the following steps: ball-milling nano nickel powder and vanadium carbide micro powder, and calcining to obtain nickel-modified vanadium carbide.

5. A high-strength seamless steel pipe according to claim 4, characterized in that: The particle size of the nano nickel powder is 50-100 nm, and the particle size of the vanadium carbide powder is 20-40 μm.

6. A high-strength seamless steel pipe according to claim 4, characterized in that: The mass ratio of the nano nickel powder to the vanadium carbide powder is 1-3:

100.

7. A high-strength seamless steel pipe according to claim 6, characterized in that: The mass ratio of the nano nickel powder to the vanadium carbide powder is 1:

50.

8. The high-strength seamless steel pipe according to claim 4, characterized in that: The calcination temperature is 560-650° C. and the calcination time is 1-2 hours.

9. The method for preparing a high-strength seamless steel pipe according to any one of claims 1 to 8, characterized in that: The following steps are involved: S1, preparing materials according to the element composition of the matrix, adding the reinforcing phase after smelting, stirring and mixing, and casting to obtain a round steel billet; S2, performing piercing and rolling on the round steel billet to obtain a hollow tube billet; S3, cooling the hollow tube blank to 500°C-600°C and keeping the temperature for 1-3 hours to obtain a heat-treated hollow tube blank; S4, quenching and cooling the heat-treated hollow tube to room temperature to obtain a room-temperature hollow tube; S5. Heat the room temperature hollow tube to 500-650° C. and keep the temperature for 0.5-1.5 hours to obtain a high-strength seamless steel tube.

10. The method for preparing a high-strength seamless steel pipe according to claim 9, characterized in that: The rolling temperature is 950-1050°C.

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