CN113416894B

CN113416894B - M65-grade resistance welding petroleum casing pipe and manufacturing method thereof

Info

Publication number: CN113416894B
Application number: CN202110568766.XA
Authority: CN
Inventors: 黄明浩; 黄国建; 孔祥磊; 王杨; 张英慧
Original assignee: Angang Steel Co Ltd
Current assignee: Angang Steel Co Ltd
Priority date: 2021-05-25
Filing date: 2021-05-25
Publication date: 2022-08-16
Anticipated expiration: 2041-05-25
Also published as: CN113416894A

Abstract

The invention relates to the technical field of petroleum casings, in particular to an M65-grade electric resistance welding petroleum casing and a manufacturing method thereof. The chemical components by weight percentage are as follows: c: 0.19 to 0.23 percent, Si: 0.15-0.30%, Mn: 1.30% -1.50%, P: less than or equal to 0.020%, S: less than or equal to 0.008 percent, Ti: 0.05% -0.08%, V: 0.03% -0.06%, Als: 0.02% -0.05%, N: less than or equal to 0.008 percent, and the balance of Fe and inevitable elements. 1) Smelting and continuous casting process: 2) the rolling process comprises the following steps: heating a continuous casting plate blank to 1150-1200 ℃ by a heating furnace, and then rolling by hot continuous rolling at the finishing temperature of 800-860 ℃; 3) cooling the rolled steel strip at the speed of 6-12 ℃/s, and coiling the steel strip at the temperature of 500-590 ℃; 4) welding the steel strip into a steel pipe; 5) carrying out heat treatment on the whole steel pipe: after ERW pipe manufacturing, heating the whole pipe to 870-900 ℃, preserving heat for 30-50 min, and cooling in air; and tempering the whole pipe, wherein the tempering temperature is 500-560 ℃, preserving the heat for 60-80 min, and then cooling with water. The heat treatment process is simplified, the steel pipe is ensured to have better weldability and impact toughness, brittle failure of the oil well pipe can be prevented, and the safety is higher.

Description

M65-grade resistance welding petroleum casing pipe and manufacturing method thereof

Technical Field

The invention relates to the technical field of petroleum casings, in particular to an M65-grade electric resistance welding petroleum casing and a manufacturing method thereof.

Background

The petroleum casing pipe is one of the most commonly used petroleum special pipes in oil fields, the annual demand is about 80-100 ten thousand tons, the petroleum casing pipe accounts for more than 40% of the total amount of the steel for the petroleum industry, and the petroleum casing pipe is an essential construction material in drilling and production operations of oil and gas fields. Compared with a seamless pipe, the HFW casing pipe has the remarkable advantages of uniform wall thickness, high size precision, good perforation performance, strong collapse resistance, low cost and the like. The replacement of conventional seamless steel pipes by ERW casings is a future development trend. The straight seam welded oil reservoir casing pipes with high added values and different levels are developed, the market competitiveness is improved, and the straight seam welded oil reservoir casing pipes have profound significance for saving oil production cost and improving the oil production level of China.

API Spec 5CT "casing and tubing Specifications": the yield strength of the M65 grade steel pipe is 448-586MPa, the tensile strength is more than or equal to 586MPa, and the elongation is more than or equal to 22 percent; the transverse Charpy impact power is more than or equal to 20J at 0 ℃, and the hardness HRC is less than or equal to 22. The heat treatment mode after the tube making can adopt normalizing, normalizing-tempering and quenching-tempering. In order to realize high-efficiency production, hot continuous rolling is adopted to roll a hot rolled steel strip with slightly low strength, then ERW welding pipe making is carried out, and heat treatment is carried out on the whole pipe, so that the final performance of the steel pipe meets the level of M65. And the welding seam and the pipe body are subjected to the same heat treatment process, the obtained final structure is the same, the structure and performance difference between the welding seam and the pipe body is effectively reduced, the residual stress is eliminated, and the integral quality of the steel pipe is improved.

CN101921952A discloses 'steel for petroleum casing pipe, electric resistance welding petroleum casing pipe and manufacturing method thereof'. The components comprise C: 0.19% -0.29%, Mn: 1.0% -1.4%; quenching and tempering heat treatment is carried out on the whole tube, and the tempering is carried out at 650-690 ℃. However, the tempering temperature is high, the energy consumption is large, and the high-temperature tempering brittleness cannot be controlled. The paper "characteristics of production process of K55 and development of M65" contains C: 0.35% -0.36%, Si: 0.23% -0.30%, Mn: 1.40% -1.43%, V: 0.05% -0.06%, S: 0.012% -0.014%, P: 0.013% -0.015%. The paper discloses a seamless pipe M65, which adopts a high carbon design, has carbon equivalent of more than 0.6, poor weldability and impact toughness of steel strips, can not be butt-welded end to end, can only be produced in a single coil, and has low production efficiency.

At present, the production of straight-seam resistance welding petroleum casing pipes M65 exists: high carbon content, poor weldability and impact toughness of steel strips, complex quenching and tempering heat treatment process and the like.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention provides the M65-grade electric resistance welding petroleum casing pipe and the manufacturing method thereof, the implementation mode is simpler, the operation is easy, the heat treatment process is simplified, the steel pipe is ensured to have better weldability and impact toughness, the brittle failure of the oil well pipe can be prevented, and the safety is higher.

In order to achieve the purpose, the invention adopts the following technical scheme:

an M65-grade resistance welding petroleum casing pipe is characterized by comprising the following chemical components in percentage by weight:

c: 0.19 to 0.23 percent, Si: 0.15-0.30%, Mn: 1.30% -1.50%, P: less than or equal to 0.020%, S: less than or equal to 0.008 percent, Ti: 0.05% -0.08%, V: 0.03% -0.06%, Als: 0.02% -0.05%, N: less than or equal to 0.008 percent, and the balance of Fe and inevitable elements.

A manufacturing method of an M65-grade electric resistance welding petroleum casing comprises the process flows of molten iron pretreatment → molten steel smelting → external refining → slab casting → continuous casting billet reheating → rolling → cooling → coiling → ERW pipe manufacturing → whole pipe heat treatment, and specifically comprises the following steps:

1) smelting and continuous casting process: the method comprises the steps of molten iron pretreatment, converter smelting, external refining, light desulphurization treatment in an LF furnace, calcium treatment and slab continuous casting; the converter smelting is top blowing or top-bottom combined blowing; the continuous casting of the slab is carried out to prepare a continuous casting slab, and the continuous casting adopts electromagnetic stirring or dynamic light pressing; the steel strip is subjected to high-frequency/medium-frequency resistance welding through an ERW unit to be made into a steel pipe;

2) the rolling process comprises the following steps: heating a continuous casting plate blank to 1150-1200 ℃ by a heating furnace, and then rolling by hot continuous rolling at the finishing temperature of 800-860 ℃;

3) cooling the rolled steel strip at the speed of 6-12 ℃/s, and coiling the steel strip at the temperature of 500-590 ℃;

4) welding the steel strip into a steel pipe;

5) carrying out heat treatment on the whole steel pipe: after ERW pipe manufacturing, heating the whole pipe to 870-900 ℃, preserving heat for 30-50 min, and cooling in air; and tempering the whole pipe, wherein the tempering temperature is 500-560 ℃, preserving the heat for 60-80 min, and then cooling with water.

Compared with the prior art, the invention has the beneficial effects that:

1) the steel has the advantages that the content of C is low, the content of Mn is moderate, C is a carbide forming element and is the most effective element for ensuring the strength, the welding performance and the impact toughness of the product can be reduced due to overhigh content of C, and the strength of steel can be effectively ensured due to Mn.

2) According to the invention, a proper amount of Ti refined grains are added, so that the hot rolling state strength is improved, and the tempering brittleness is reduced; adding a proper amount of V element to ensure that crystal grains do not grow obviously after normalizing; the Ti is adopted to reduce the tempering brittleness, so that the steel pipe is ensured to have better impact toughness, the brittle failure of the oil well pipe can be prevented, and the safety is higher.

3) By adopting normalizing-tempering, the implementation mode is simpler and the operation is easy;

4) normalizing-tempering heat treatment is adopted for the whole pipe, and after the normalizing treatment, a structure close to a balanced state is obtained, a banded structure and residual stress are eliminated, and the impact toughness is improved; after tempering, the residual stress caused by cooling is further eliminated, and the overall quality of the steel pipe is improved.

5) The whole pipe adopts normalizing-tempering heat treatment, thereby ensuring the consistency of the performance of the pipe body and the welding line, effectively reducing the difference of the structure and the performance of the welding line and the pipe body, having good weldability between coils, realizing multi-coil production and having high efficiency.

Detailed Description

The invention discloses an M65-grade electric resistance welding petroleum casing pipe and a manufacturing method thereof. Those skilled in the art can modify the process parameters appropriately to achieve the desired results with reference to the disclosure herein. It is expressly intended that all such similar substitutes and modifications which would be obvious to one skilled in the art are deemed to be included in the invention. While the methods and applications of this invention have been described in terms of preferred embodiments, it will be apparent to those of ordinary skill in the art that variations and modifications in the methods and applications described herein, as well as other suitable variations and combinations, may be made to implement and use the techniques of this invention without departing from the spirit and scope of the invention.

An M65-grade electric resistance welding petroleum casing comprises the following chemical components in percentage by weight:

C: the element is a carbide forming element and is the most effective element for ensuring the strength, the hardenability and the performance stability after heat treatment can be improved, and the performance of the steel pipe after normalizing-tempering heat treatment can meet the requirement of M65. Therefore, the carbon content should not be too low; however, too high carbon content will reduce the weldability and impact toughness of the product, and the optimal range is 0.19-0.23%.

Si: can play a role of solid solution strengthening, but the plasticity and the toughness of the steel are reduced due to the over high content of the carbon steel, and the optimal range is 0.15 to 0.30 percent.

Mn: manganese has a solid solution strengthening effect, can also increase the stability of austenite, is also favorable for improving the hardenability, and effectively ensures the strength of steel. Manganese can reduce the martensite transformation temperature Ms and increase the content of residual austenite, and meanwhile, the influence of manganese on the toughness of the steel plate is not large. However, if the manganese content is too high, the center segregation tendency of the continuous casting slab is increased, the band structure of the steel sheet is increased, and the steel sheet is preserved after heat treatment, and finally the steel sheet contains a certain amount of band structure, and hard phases such as bainite and martensite are accumulated in the band structure, so that the brittleness of the steel sheet is increased, the plasticity is reduced, and the mechanical properties are reduced. The optimal range is 1.30-1.50%.

P: phosphorus is a harmful element in steel, increases the cold brittleness of the steel, deteriorates the welding performance, reduces the plasticity, deteriorates the cold bending performance, and the content of the phosphorus is controlled to be less than or equal to 0.020%.

S: sulfur is a harmful element in steel, so that the steel generates hot brittleness, the ductility and the toughness of the steel are reduced, the welding performance is deteriorated, and the content of the sulfur is controlled to be less than or equal to 0.008 percent in order to ensure the high purity of molten steel.

Ti: titanium is a strong carbide forming element, and when about 0.015 percent of Ti is added, a high-temperature stable fine TiN precipitated phase can be formed during slab continuous casting, the fine TiN precipitated phase can effectively prevent austenite grains of a continuous casting billet from growing in the heating process, and meanwhile, the fine TiN precipitated phase has an obvious effect of improving the toughness of a heat affected zone during steel welding. More Ti content can obtain more TiC particles, and the strength of the steel is improved through strain-induced precipitation and phase-change precipitation. Meanwhile, the precipitated TiC has a strong precipitation strengthening effect, so that grains of the steel pipe subjected to subsequent normalizing heat treatment are not obviously grown, and the strength of the whole pipe subjected to heat treatment meets the performance requirement of M65. Meanwhile, when the normalizing temperature is lower than 900 ℃, the appropriate amount of Ti can improve the yield strength without reducing the impact toughness. However, when the Ti content is too high, the strength is not increased any more, the impact energy is sharply reduced, and the alloy cost is high. The optimal range is 0.06% -0.12%.

V: vanadium carbonitride is uniformly precipitated in ferrite in a fine dispersion mode, has a fine-grain strengthening effect, can obviously improve the yield strength and the tensile strength of the material, and simultaneously improves the low-temperature impact toughness; when the steel is melted into austenite at high temperature, the hardenability of the steel can be increased; the solid solution has strong solid solution strengthening effect when dissolved in ferrite. During the tempering heat treatment, the strength and toughness of the steel can be improved. However, too high increases the cost of the alloy, and a suitable range is 0.03% to 0.06%.

And Als: aluminum is a commonly used deoxidizer, and a small amount of aluminum is added into steel, so that grains can be refined, the impact toughness is improved, and the proper range is 0.02-0.05%.

N: the solid-solution nitrogen has strong pinning dislocation effect and adverse effect on toughness, and the content of the solid-solution nitrogen is controlled to be less than or equal to 0.008 percent.

1) smelting and continuous casting process: the method comprises the steps of molten iron pretreatment, converter smelting, top blowing or top-bottom combined blowing, external refining, LF furnace light desulfurization treatment and calcium treatment to control the shape of impurities and improve the ductility, toughness and cold bending performance of steel, continuous casting of a slab to form a continuous casting slab, and electromagnetic stirring or dynamic light pressing for continuous casting to improve the quality of the continuous casting slab.

2) The rolling process comprises the following steps: heating the continuous casting plate blank to 1150-1200 ℃ by a heating furnace, then rolling by hot continuous rolling at the finishing temperature of 800-860 ℃, cooling the rolled steel strip at the speed of 6-12 ℃/s, and coiling the steel strip at the temperature of 500-590 ℃. At the cooling speed, the method is beneficial to refining pearlite spacing, can obviously improve yield strength and tensile strength, and simultaneously improves toughness. Coiling at 590 ℃ of 500-.

3) The yield strength of the hot rolled steel strip is more than 550MPa, the tensile strength is more than 650MPa, the elongation is 33% -37%, and the microstructure is ferrite-pearlite.

4) And (3) carrying out high-frequency/medium-frequency resistance welding on the steel strip by an ERW unit to prepare a steel pipe. The whole tube heat treatment process comprises the following steps: after ERW pipe making, heating the whole pipe to 870 ℃ and 900 ℃, preserving heat for 30-50 min, and cooling in air; and tempering the whole pipe, wherein the tempering temperature is 500-560 ℃, preserving the heat for 60-80 min, and then cooling with water to effectively inhibit the high-temperature tempering brittleness.

5) The structure of the whole pipe after heat treatment is ferrite-bainite and a small amount of pearlite, the yield strength is 480-550 MPa, the tensile strength is more than 600MPa, the elongation is 30-36%, and the transverse Charpy impact energy Akv at-10 ℃ is more than or equal to 100J.

[ examples ] A method for producing a compound

The chemical components of the M65-grade resistance welding petroleum casing pipe comprise the following components in percentage by weight, and are shown in Table 1:

TABLE 1M 65-grade electric resistance welding petroleum casing chemical composition wt%

Examples	C	Si	Mn	P	S	Ti	V	Als	N
										1	0.22	0.22	1.33	0.012	0.004	0.05	0.04	0.03	0.0046
2	0.20	0.3	1.42	0.013	0.003	0.07	0.06	0.03	0.0042
										3	0.19	0.17	1.40	0.012	0.002	0.06	0.03	0.04	0.0040
4	0.23	0.12	1.35	0.011	0.005	0.08	0.04	0.03	0.0043
										5	0.19	0.15	1.45	0.012	0.003	0.05	0.05	0.04	0.0045
6	0.22	0.25	1.38	0.009	0.002	0.05	0.03	0.03	0.0048

The manufacturing method of the M65-grade electric resistance welding petroleum casing pipe comprises the process flows of molten iron pretreatment → molten steel smelting → external refining → slab continuous casting → continuous casting billet reheating → rolling → cooling → coiling → ERW pipe manufacturing → whole pipe heat treatment. The mechanical properties of the heating, rolling and hot rolling conditions are shown in Table 2, and the heat treatment process is shown in Table 3.

TABLE 2 heating, Rolling Process and Hot rolled State mechanical Properties

TABLE 3 Heat treatment Process

The yield strength of the hot rolled steel strip is more than 550MPa, the tensile strength is more than 650MPa, the elongation is 33% -37%, and the microstructure is ferrite-pearlite. The structure of the whole pipe after heat treatment is ferrite-bainite and a small amount of pearlite, the yield strength is 480-550 MPa, the tensile strength is more than 600MPa, the elongation is 30-36%, the transverse Charpy impact energy Akv at minus 10 ℃ is more than or equal to 100J, and the mechanical properties in a heat treatment state are shown in Table 4.

TABLE 4 mechanical properties in the heat-treated state

As can be seen from Table 4, the normalized-tempered straight seam electric resistance welded petroleum casing produced by the component design, rolling and pipe-shaping heat treatment process meets the requirements of API SPEC 5CT standard on M65-grade steel pipes.

The method has the advantages of simpler implementation mode, easy operation and simplified heat treatment process, meets the requirement of API SPEC 5CT standard on M65-grade steel pipes, ensures that the steel pipes have better weldability and impact toughness, can prevent brittle failure of oil well pipes, and has higher safety.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered to be within the technical scope of the present invention, and the technical solutions and the inventive concepts thereof according to the present invention should be equivalent or changed within the scope of the present invention.

Claims

1. The manufacturing method of the M65-grade resistance welding petroleum casing pipe is characterized in that the M65-grade resistance welding petroleum casing pipe comprises the following chemical components in percentage by weight:

c: 0.19 to 0.23 percent, Si: 0.15-0.30%, Mn: 1.35% -1.50%, P: less than or equal to 0.020%, S: less than or equal to 0.008 percent, Ti: 0.05% -0.08%, V: 0.03% -0.05%, Als: 0.02% -0.05%, N: less than or equal to 0.008 percent, and the balance of Fe and inevitable elements;

the process flow comprises the steps of molten iron pretreatment → molten steel smelting → external refining → slab continuous casting → continuous casting billet reheating → rolling → cooling → coiling → ERW pipe manufacturing → whole pipe heat treatment, and specifically comprises the following steps:

1) smelting and continuous casting process: the method comprises the steps of molten iron pretreatment, converter smelting, external refining, light desulphurization treatment in an LF furnace, calcium treatment and slab continuous casting;

4) welding the steel strip into a steel pipe;

5) carrying out heat treatment on the whole steel pipe: after ERW pipe manufacturing, heating the whole pipe to 870-900 ℃, preserving heat for 30-45 min, and air cooling; and tempering the whole pipe, wherein the tempering temperature is 530-560 ℃, preserving the heat for 60-80 min, and then cooling with water.

2. The method for manufacturing the M65-grade electric resistance welding oil casing according to claim 1, wherein the converter smelting in the step 1) is top-blown or top-bottom combined blowing.

3. The method for manufacturing the M65-grade electric resistance welded petroleum casing pipe according to claim 1, wherein the continuous casting of the plate blank in the step 1) is performed by electromagnetic stirring or dynamic soft pressing.

4. The method for manufacturing the M65-grade electric resistance welded oil casing according to claim 1, wherein the steel strip in the step 1) is subjected to high-frequency/medium-frequency electric resistance welding by an ERW unit to manufacture a steel pipe.