Pressure-resistant seamless steel pipe

Abstract

The invention relates to the technical field of steel pipes, and provides a pressure-resistant seamless steel pipe which comprises a matrix and a reinforcing phase, the matrix is composed of the following elements in percentage by weight: 0.02%-0.08% of copper, 2.5%-4.6% of manganese, 1.6%-4.5% of vanadium, 0.1%-0.6% of aluminum, 0.08%-0.15% of carbon, 0.25%-0.39% of silicon, 0.0023%-0.009% of phosphorus, 0.001%-0.011% of sulfur and the balance of iron and inevitable impurities; the reinforcing phase comprises titanium dioxide, and the mass ratio of the reinforcing phase to the matrix is (1.8-4.0): 100. By means of the technical scheme, the problem that in the prior art, the yield strength of a pressure-resistant seamless steel pipe is poor is solved.

Description

Technical Field

[0001] The invention relates to the technical field of pressure-resistant materials, and in particular to a pressure-resistant seamless steel pipe. Background Art

[0002] In the industrial field, with the continuous emergence of various high-pressure working conditions, pressure-resistant seamless steel pipes have emerged and gradually occupied a key position. When subjected to high pressure, traditional steel pipes are prone to weld cracking and leakage, which seriously affect the safety and stability of the system. In the petrochemical industry, the extraction and transportation of crude oil involves a high-pressure environment. Ordinary steel pipes cannot meet the requirements of long-term stable operation, which has given rise to the research and development needs of seamless structures and high-pressure steel pipes. In the energy field, whether it is the long-distance transportation of natural gas, its pipelines need to withstand huge pressure to ensure efficient transportation, or in thermal power generation, the high-temperature and high-pressure transmission of steam, there is an urgent need for steel pipe materials that can withstand extreme pressure conditions. In the manufacturing industry, the manufacture of hydraulic systems, high-pressure vessels and other equipment also puts forward strict standards for the pressure resistance of steel pipes, which promotes the continuous technological innovation of pressure-resistant seamless steel pipes in material selection, manufacturing processes, etc., to adapt to the growing high-pressure application scenarios of modern industry and ensure the safety, efficiency and sustainable development of industrial production.

[0003] However, the yield strength of existing seamless steel pipes is not high, resulting in poor pressure resistance of seamless steel pipes. Therefore, it is very important to develop a pressure-resistant seamless steel pipe with high yield strength. Summary of the invention

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

[0005] The technical solution of the present invention is as follows: The present invention provides a pressure-resistant seamless steel pipe, comprising a matrix and a reinforcement phase, wherein the matrix is ​​composed of the following elements in percentage by weight: 0.02% to 0.08% copper, 2.5% to 4.6% manganese, 1.8% to 4.5% vanadium, 0.1% to 0.6% aluminum, 0.08% to 0.15% carbon, 0.25% to 0.39% silicon, 0.0023% to 0.009% phosphorus, 0.001% to 0.011% sulfur, and the remainder is iron and unavoidable impurities; The reinforcing phase includes titanium dioxide, and the mass ratio of the reinforcing phase to the matrix is ​​1.8-4.0:100.

[0006] As a further technical solution, the mass ratio of the manganese to the vanadium is 1-2:1.

[0007] The invention further improves the yield strength of the seamless steel pipe by adjusting the mass ratio of manganese to vanadium in the matrix element composition to 1-2:1.

[0008] As a further technical solution, the mass ratio of the manganese to the vanadium is 1.5:1.

[0009] The present invention further improves the yield strength of the seamless steel pipe by adjusting the mass ratio of manganese to vanadium in the matrix element composition to 1.5:1.

[0010] As a further technical solution, the titanium dioxide is niobium-modified titanium dioxide, and the preparation process of the niobium-modified titanium dioxide includes the following steps: ball-milling nano-niobium powder and titanium dioxide powder, and calcining to obtain niobium-modified titanium dioxide.

[0011] The invention uses nano niobium powder to modify titanium dioxide powder, and calcines to obtain niobium-modified titanium dioxide, thereby further improving the yield strength of the seamless steel pipe.

[0012] As a further technical solution, the particle size of the nano niobium powder is 50-80 nm, and the particle size of the titanium dioxide powder is 10-50 μm.

[0013] As a further technical solution, the mass ratio of the nano niobium powder to the titanium dioxide powder is 3-5:100.

[0014] The invention further improves the yield strength of the seamless steel pipe by adjusting the mass ratio of nano niobium powder to titanium dioxide micropowder in the niobium modified titanium dioxide raw material to 3-5:100.

[0015] As a further technical solution, the mass ratio of the nano niobium powder to the titanium dioxide powder is 1:25.

[0016] The invention further improves the yield strength of the seamless steel pipe by adjusting the mass ratio of nano niobium powder to titanium dioxide powder in the niobium modified titanium dioxide raw material to 1:25.

[0017] As a further technical solution, the calcination temperature is 600-680° C. and the calcination time is 1-3 hours.

[0018] The present invention also proposes a method for preparing a pressure-resistant 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 to 400° C. to 520° C., and keeping the temperature for 0.5 to 2.5 hours to obtain a heat-treated hollow tube; 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 550-630° C. and keep it warm for 1-2 hours to obtain a pressure-resistant seamless steel tube.

[0019] As a further technical solution, the rolling temperature is 1000~1200℃.

[0020] The working principle and beneficial effects of the present invention are: In the present invention, the pressure-resistant steel pipe includes a matrix and a reinforcement phase. In the element composition of the matrix, the proportion of manganese and vanadium is increased, and the yield strength of the seamless steel pipe is improved; titanium dioxide is added as a reinforcement phase, which significantly improves the yield strength of the seamless steel pipe. DETAILED DESCRIPTION

[0021] 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.

[0022] In the following embodiments and comparative examples, the copper in the matrix elements of the seamless steel pipe is derived from the copper-iron alloy, containing 70wt% copper, the manganese is derived from the manganese-iron alloy, containing 65wt% manganese, the vanadium is derived from the vanadium-iron alloy, containing 40wt% vanadium, the aluminum is derived from the aluminum-iron alloy, containing 15wt% aluminum, the silicon is derived from the silicon-iron alloy, containing 20wt% silicon, the iron content in the scrap steel is 98wt%, the purity of the titanium dioxide micropowder is 99wt%, the particle size is 20μm, and the purity of the nano niobium powder is 99.9wt%, and the particle size is 50nm.

[0023] Example 1 A pressure-resistant seamless steel pipe comprises a matrix and a reinforcement phase, wherein the matrix is ​​composed of the following elements in percentage by weight: 0.08% copper, 4.6% manganese, 1.6% vanadium, 0.6% aluminum, 0.15% carbon, 0.39% silicon, 0.009% phosphorus, 0.011% sulfur, and the balance is iron and unavoidable impurities; The reinforcement phase includes titanium dioxide, and the mass ratio of the reinforcement phase to the matrix is ​​1:25.

[0024] The preparation method thereof comprises the following steps: S1. According to the element composition of the matrix, copper-iron alloy, manganese-iron alloy, vanadium-iron alloy, aluminum-iron alloy, silicon-iron alloy and scrap steel are weighed and mixed, and a reinforcing phase is added after smelting, stirred and mixed, and cast to obtain a round steel billet; S2, piercing and rolling the round steel billet at a rolling temperature of 1200° C. to obtain a hollow tube billet; S3, cooling the hollow tube to 520°C and keeping the temperature for 0.5h to obtain a heat-treated hollow tube; S4, the heat-treated hollow tube blank is quenched and cooled to room temperature to obtain a room temperature hollow tube blank; S5. Heat the room temperature hollow tube to 630°C and keep it warm for 1 hour to obtain a pressure-resistant seamless steel tube.

[0025] Example 2 A pressure-resistant seamless steel pipe comprises a matrix and a reinforcement phase, wherein the matrix is ​​composed of the following elements in percentage by weight: 0.02% copper, 2.5% manganese, 4.5% vanadium, 0.1% aluminum, 0.08% carbon, 0.25% silicon, 0.0023% phosphorus, 0.001% sulfur, and the balance is iron and unavoidable impurities; The reinforcement phase includes titanium dioxide, and the mass ratio of the reinforcement phase to the matrix is ​​1.8:100.

[0026] The preparation method thereof comprises the following steps: S1. According to the element composition of the matrix, copper-iron alloy, manganese-iron alloy, vanadium-iron alloy, aluminum-iron alloy, silicon-iron alloy and scrap steel are weighed and mixed, and a reinforcing phase is added after smelting, stirred and mixed, and cast to obtain a round steel billet; 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 400°C and keeping it at that temperature for 2.5 hours to obtain a heat-treated hollow tube; S4, the heat-treated hollow tube blank is quenched and cooled to room temperature to obtain a room temperature hollow tube blank; S5. Heat the room temperature hollow tube to 550°C and keep it warm for 2 hours to obtain a pressure-resistant seamless steel tube.

[0027] Example 3 A pressure-resistant seamless steel pipe comprises a matrix and a reinforcement phase, wherein the matrix is ​​composed of the following elements in weight percentage: 0.06% copper, 4.2% manganese, 1.8% vanadium, 0.5% aluminum, 0.12% carbon, 0.31% silicon, 0.0056% phosphorus, 0.008% sulfur, and the balance is iron and unavoidable impurities; The reinforcement phase includes titanium dioxide, and the mass ratio of the reinforcement phase to the matrix is ​​3:100.

[0028] The preparation method thereof comprises the following steps: S1. According to the element composition of the matrix, copper-iron alloy, manganese-iron alloy, vanadium-iron alloy, aluminum-iron alloy, silicon-iron alloy and scrap steel are weighed and mixed, and a reinforcing phase is added after smelting, stirred and mixed, and cast to obtain a round steel billet; S2, piercing and rolling the round steel billet at a rolling temperature of 1100° C. to obtain a hollow tube billet; S3, cooling the hollow tube to 450°C and keeping the temperature for 1.5 hours to obtain a heat-treated hollow tube; S4, the heat-treated hollow tube blank is quenched and cooled to room temperature to obtain a room temperature hollow tube blank; S5. Heat the room temperature hollow tube to 600°C and keep it warm for 1.5 hours to obtain a pressure-resistant seamless steel tube.

[0029] 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: 0.06% copper, 2.7% manganese, 3.3% vanadium, 0.5% aluminum, 0.12% carbon, 0.31% silicon, 0.0056% phosphorus, 0.008% sulfur, and the remainder is iron and unavoidable impurities.

[0030] 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: 0.06% copper, 3.0% manganese, 3.0% vanadium, 0.5% aluminum, 0.12% carbon, 0.31% silicon, 0.0056% phosphorus, 0.008% sulfur, and the remainder is iron and unavoidable impurities.

[0031] 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: 0.06% copper, 3.6% manganese, 2.4% vanadium, 0.5% aluminum, 0.12% carbon, 0.31% silicon, 0.0056% phosphorus, 0.008% sulfur, and the remainder is iron and unavoidable impurities.

[0032] Example 7 The only difference between this embodiment and embodiment 3 is that this embodiment is composed of the following elements in weight percentage: 0.06% copper, 4.0% manganese, 2.0% vanadium, 0.5% aluminum, 0.12% carbon, 0.31% silicon, 0.0056% phosphorus, 0.008% sulfur, and the balance is iron and unavoidable impurities.

[0033] Example 8 The only difference between this embodiment and embodiment 6 is that the titanium dioxide in this embodiment is niobium-modified titanium dioxide, and the preparation process of niobium-modified titanium dioxide includes the following steps: ball milling nano-niobium powder and titanium dioxide micropowder, the mass ratio of nano-niobium powder to titanium dioxide micropowder is 3:100, and calcining at 650° C. for 2 h to obtain niobium-modified titanium dioxide.

[0034] Example 9 The only difference between this embodiment and embodiment 8 is that the mass ratio of nano niobium powder to titanium dioxide powder in this embodiment is 1:25.

[0035] Example 10 The only difference between this embodiment and embodiment 8 is that the mass ratio of nano niobium powder to titanium dioxide powder in this embodiment is 1:20.

[0036] Comparative Example 1 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: 0.02% copper, 7.0% manganese, 0.1% aluminum, 0.08% carbon, 0.25% silicon, 0.0023% phosphorus, 0.001% sulfur, and the balance is iron and unavoidable impurities.

[0037] 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: 0.02% copper, 7.0% vanadium, 0.1% aluminum, 0.08% carbon, 0.25% silicon, 0.0023% phosphorus, 0.001% sulfur, and the balance is iron and unavoidable impurities.

[0038] 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: 0.02% copper, 0.1% aluminum, 0.08% carbon, 0.25% silicon, 0.0023% phosphorus, 0.001% sulfur, and the balance is iron and unavoidable impurities.

[0039] Comparative Example 4 The only difference between this comparative example and Example 2 is that this comparative example has no reinforcing phase.

[0040] The yield strength of the seamless steel pipes prepared in Examples 1 to 10 and Comparative Examples 1 to 4 was tested in accordance with GB / T 228.1-2021 “Tensile Test of Metallic Materials Part 1: Room Temperature Test Method”, and the measured data are shown in Table 1.

[0041] Table 1 Yield strength test results of various examples and comparative examples

[0042] Comparing Example 2 with Comparative Examples 1 to 3, it is shown that the addition of manganese and vanadium in the present invention improves the yield strength of the seamless steel pipe. Comparing Example 2 with Comparative Example 4, it is shown that the addition of titanium dioxide as a reinforcing phase in the present invention improves the yield strength of the seamless steel pipe. Comparing Examples 5 to 7 with Examples 3 to 4, it is shown that the yield strength of the seamless steel pipe is further improved by adjusting the mass ratio of manganese to vanadium to 1 to 2:1. Comparing Example 6 with Example 5 and Example 7, it is shown that when the mass ratio of manganese to vanadium is adjusted to 1.5:1, the yield strength of the seamless steel pipe is improved best. Comparing Examples 8 to 10 with Example 6, it is shown that the use of niobium-modified titanium dioxide in the present invention further improves the yield strength of the seamless steel pipe. Comparing Example 9 with Example 8 and Example 10, it is shown that when the mass ratio of nano-niobium powder to titanium dioxide micropowder in the niobium-modified titanium dioxide raw material is 1:25, the yield strength of the seamless steel pipe is improved best, solving the problem of poor yield strength of the pressure-resistant steel pipe.

[0043] 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 pressure-resistant 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: 0.02% to 0.08% copper, 2.5% to 4.6% manganese, 1.6% to 4.5% vanadium, 0.1% to 0.6% aluminum, 0.08% to 0.15% carbon, 0.25% to 0.39% silicon, 0.0023% to 0.009% phosphorus, 0.001% to 0.011% sulfur, and the balance is iron and unavoidable impurities; The reinforcing phase includes titanium dioxide, and the mass ratio of the reinforcing phase to the matrix is ​​1.8-4.0:

100.

2. A pressure-resistant seamless steel pipe according to claim 1, characterized in that: The mass ratio of the manganese to the vanadium is 1-2:

1.

3. A pressure-resistant seamless steel pipe according to claim 2, characterized in that: The mass ratio of the manganese to the vanadium is 1.5:

1.

4. A pressure-resistant seamless steel pipe according to claim 1, characterized in that: The titanium dioxide is niobium-modified titanium dioxide, and the preparation process of the niobium-modified titanium dioxide comprises the following steps: ball-milling nano-niobium powder and titanium dioxide micropowder, and calcining to obtain niobium-modified titanium dioxide.

5. A pressure-resistant seamless steel pipe according to claim 4, characterized in that: The particle size of the nano niobium powder is 50-80 nm, and the particle size of the titanium dioxide powder is 10-50 μm.

6. A pressure-resistant seamless steel pipe according to claim 4, characterized in that: The mass ratio of the nano niobium powder to the titanium dioxide powder is 3-5:

100.

7. A pressure-resistant seamless steel pipe according to claim 6, characterized in that: The mass ratio of the nano niobium powder to the titanium dioxide powder is 1:

25.

8. A pressure-resistant seamless steel pipe according to claim 4, characterized in that: The calcination temperature is 600-680° C. and the calcination time is 1-3 hours.

9. The method for preparing a pressure-resistant 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 to 400° C. to 520° C., and keeping the temperature for 0.5 to 2.5 hours to obtain a heat-treated hollow tube; S4, the heat-treated hollow tube blank is quenched and cooled to room temperature to obtain a room temperature hollow tube blank; S5. Heat the room temperature hollow tube to 550-630° C. and keep it warm for 1-2 hours to obtain a pressure-resistant seamless steel tube.

10. The method for preparing a pressure-resistant seamless steel pipe according to claim 9, characterized in that: The rolling temperature is 1000-1200°C.

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