CN110616365A

CN110616365A - High-strength expansion casing pipe and manufacturing method thereof

Info

Publication number: CN110616365A
Application number: CN201810638363.6A
Authority: CN
Inventors: 董晓明; 张忠铧; 高展
Original assignee: Baoshan Iron and Steel Co Ltd
Current assignee: Baoshan Iron and Steel Co Ltd; Yantai Lubao Steel Pipe Co Ltd
Priority date: 2018-06-20
Filing date: 2018-06-20
Publication date: 2019-12-27
Anticipated expiration: 2038-06-20
Also published as: CN110616365B

Abstract

The invention discloses a high-strength expansion sleeve, which comprises the following chemical elements in percentage by mass: c: 0.1-0.2%, Si: 0.1-0.4%, Mn: 3-6%, V: 0.05 to 0.2%, Ca 0.0005 to 0.005%, Ti: 0.01-0.04%, Al: 0.01 to 0.05 percent, at least one of Cr less than or equal to 0.5 percent, Mo less than or equal to 0.5 percent and Nb less than or equal to 0.04 percent, and the balance of Fe and other inevitable impurities. The invention also discloses a manufacturing method of the high-strength expansion casing, which comprises the following steps: (1) smelting and continuously casting to obtain a tube blank; (2) perforating and continuously rolling the tube blank; (3) and (3) heat treatment: heating the steel pipe to an austenitizing temperature Ac1+30 ℃ to Ac3-30 ℃, preserving heat for 30-60min, and then performing water quenching; then tempering at the temperature of 650 plus 720 ℃ for 50-80 min; and then hot sizing.

Description

High-strength expansion casing pipe and manufacturing method thereof

Technical Field

The present invention relates to a casing and a method for manufacturing the same, and more particularly, to an expandable casing and a method for manufacturing the same.

Background

The expansion casing pipe is a special petroleum special pipe, and has good expansion performance, and the mechanical performance of the expanded casing pipe reaches the corresponding steel grade casing pipe of American Petroleum Institute (API) standard so as to meet engineering application requirements. However, the expansion ratio is limited by the mechanical properties of the expansion casing in the prior art, and when the expansion ratio exceeds 20%, the expansion casing is prone to have a problem of uneven wall thickness, so that the local wall thickness of the expansion casing is reduced, and the mechanical properties of the whole expansion casing are reduced, so that obtaining the expansion casing with high elongation is a major technical difficulty in the prior art. In addition, the wall thickness of the expanded casing is reduced after the expansion and the crushing effect reduces the collapse resistance of the expanded casing, so that the yield strength of the expanded casing after deformation needs to be improved so as to improve the collapse resistance of the expanded casing.

In the prior art, chinese patent publication No. CN101755068B, published as 7/4/2012 entitled "steel pipe excellent in deformation properties and method for manufacturing the same" discloses a steel pipe excellent in deformation properties, which has a two-phase structure, but does not provide an elongation index and cannot satisfy the requirement of the expansion sleeve for a large deformation amount.

Chinese patent publication No. CN101144376A, published as 2008/3/19, entitled "continuous expansion pipe", discloses a continuous expansion pipe, but its elongation is only 25% to 30%, and cannot meet the requirement of expansion casing for high elongation.

In view of the above, it is desirable to obtain a high-strength expanded casing, which has high strength and elongation, so as to solve the problems of low strength and poor plasticity of the expanded casing in the prior art, improve the pressure resistance of the expanded casing used in the well, and meet the requirements of the field of oil field exploitation for the high-strength expanded casing.

Disclosure of Invention

One of the purposes of the invention is to provide a high-strength expansion casing which has higher strength and elongation, so that the problems of low strength and poor plasticity of the expansion casing after expansion in the prior art can be solved, the pressure resistance of the expansion casing used in a well is improved, and the requirement of the oil field exploitation field on the high-strength expansion casing is met.

In order to achieve the purpose, the invention provides a high-strength expansion casing which comprises the following chemical elements in percentage by mass:

c: 0.1-0.2%, Si: 0.1-0.4%, Mn: 3-6%, V: 0.05 to 0.2%, Ca 0.0005 to 0.005%, Ti: 0.01-0.04%, Al: 0.01 to 0.05 percent, at least one of Cr less than or equal to 0.5 percent, Mo less than or equal to 0.5 percent and Nb less than or equal to 0.04 percent, and the balance of Fe and other inevitable impurities.

The design principle of each chemical element in the high-strength expansion casing pipe is as follows:

c: c is a precipitate forming element and can improve the strength of the steel. When the C content is less than 0.10%, hardenability of the steel is lowered, and it is difficult to simultaneously secure high strength and high plasticity. When the content of C is more than 0.20%, formation of ferrite structure is suppressed to lower plasticity, and C forms a large amount of coarse precipitates with Cr and Mo to significantly increase segregation of steel, resulting in significant reduction of plasticity. Therefore, the present invention limits the mass percentage of C in the high-strength expansion casing to 0.1 to 0.2%.

Si: the yield strength of steel can be improved by solid solution of Si in ferrite, but too high Si content deteriorates workability and toughness. If the Si content is less than 0.1%, the steel is easily oxidized. Therefore, the present invention limits the mass percentage of Si in the high-strength expansion sleeve to 0.1 to 0.4%.

Mn: mn is an austenite forming element, and can stabilize austenite in steel and suppress decomposition of MA when the steel pipe is cooled. In order to obtain a certain amount of granular bainite structure, the Mn content needs to be controlled to 3% or more. However, when the Mn content is more than 6%, the structure segregation in the steel is significantly increased, affecting the uniformity and impact properties of the hot rolled structure. Therefore, the present invention limits the mass percentage of Mn in the high-strength expansion sleeve to 3 to 6%.

V: v is a typical precipitation strengthening element and can compensate for the decrease in strength due to the decrease in carbon content. When the content of V is less than 0.05%, it is difficult to achieve a strengthening effect of the material of 110ksi (i.e., a yield strength of 758 MPa). When the content of V is more than 0.2%, coarse V (cn) is easily formed, and the toughness is lowered. Therefore, the present invention limits the mass percentage of V in the high-strength expansion casing to 0.05 to 0.2%.

Ca: ca can purify molten steel, promote MnS spheroidization and improve impact toughness, but coarse non-metallic inclusions are easily formed when the content of Ca is too high. Therefore, the present invention limits the mass percentage of Ca in the high-strength expansion sleeve to 0.0005 to 0.005%.

Ti: ti is a strong carbonitride forming element, austenite grains can be obviously refined, the strength reduction caused by the reduction of the carbon content is compensated, and when the Ti content is higher than 0.04%, coarse TiN is easily formed, and the toughness of the material is reduced. Therefore, the present invention limits the mass percentage of Ti in the high-strength expansion sleeve to 0.01 to 0.04%.

Al: al is a traditional deoxidizing nitrogen-fixing element, can refine grains, and is not suitable to be too high in content considering that the yield ratio of the material is reduced. Therefore, the mass percentage of Al in the high-strength expansion sleeve is limited to 0.01-0.05%.

Cr: cr is an element that strongly improves hardenability and is a strong precipitate-forming element, precipitates can be precipitated during tempering to improve the strength of steel, but if the Cr content is more than 0.5%, coarse M is easily precipitated in grain boundaries₂₃C₆Precipitates, lowering the toughness. Therefore, the invention limits the mass percent of Cr in the high-strength expansion sleeve to be less than or equal to 0.5 percent.

Mo: mo is mainly formed by precipitates and solid solution strengthening to improve the strength and the tempering stability of steel. In the high-strength expansion sleeve pipe, the carbon content is low, so that the Mo content is higher than 0.5%, the steel strength is hardly obviously improved, and alloy waste is easily caused. Therefore, the mass percent of Mo in the high-strength expansion sleeve is limited to be less than or equal to 0.5 percent.

Nb: nb is a refined crystal grain and a precipitation strengthening element, and can compensate for a decrease in strength due to a decrease in carbon content. When the Nb content is more than 0.04%, coarse Nb (cn) is easily formed, and the toughness is lowered. Therefore, the mass percent of Nb in the high-strength expansion casing is limited to be less than or equal to 0.04 percent.

Further, in the high-strength expansion sleeve of the present invention, among the other inevitable impurities, P is not more than 0.015%, S is not more than 0.005%, and N is not more than 0.008%.

Furthermore, the microstructure of the high-strength expansion sleeve is ferrite, tempered sorbite and granular bainite.

Further, in the high strength expansion sleeve according to the present invention, the area ratio of the granular bainite is 5 to 10%.

Further, in the high strength expansion sleeve according to the present invention, the ferrite area ratio is 20 to 50%.

Further, in the high-strength expansion casing pipe, the yield strength before expansion of the high-strength expansion casing pipe is 400-600MPa, the tensile strength is 700-950MPa, the yield ratio is less than or equal to 0.7, and the elongation is more than or equal to 35%.

Furthermore, in the high-strength expansion sleeve, the yield strength of the high-strength expansion sleeve after being strengthened by 10-20% of expansion deformation is 800-.

Accordingly, another object of the present invention is to provide a method for manufacturing the high strength expanded casing, which includes optimizing a process design to obtain an expanded casing with high strength and elongation, so as to solve the problems of low strength and poor plasticity of the expanded casing after expansion in the prior art, improve the pressure resistance of the expanded casing used in a well, and meet the requirements of the field of oil field exploitation for the high strength expanded casing.

In order to achieve the above object, the present invention provides a method for manufacturing the high strength expansion casing, which comprises the steps of:

(1) smelting and continuously casting to obtain a tube blank;

(2) perforating and continuously rolling the tube blank;

(3) and (3) heat treatment: heating the steel pipe to an austenitizing temperature Ac1+30 ℃ to Ac3-30 ℃, preserving heat for 30-60min, and then performing water quenching; then tempering at the temperature of 650 plus 720 ℃ for 50-80 min; and then hot sizing.

In the above manufacturing method, in the step (1), in some embodiments, the molten steel is smelted by an electric furnace, subjected to refining outside the furnace, vacuum degassing and argon stirring, subjected to inclusion modification by Ca treatment to reduce the O, H content, and then the alloy is cast into a round billet. In the step (3), the austenitizing temperature is limited to the range of Ac1+30 ℃ to Ac3-30 ℃ in order to obtain a ferrite-austenite two-phase structure, thereby ensuring the ferrite proportion in the steel and improving the plasticity of the steel. In step (3), Ac1 ═ 723 to 10.7[ Mn%]－16.9[Ni％]+29.1[Si％]+16.9[Cr％]+290[As％]+6.38[W％]In the formula, Mn, Ni, Si, Cr, As, and W each represent a mass percentage thereof, and values when the above-defined formula is substituted should be substituted before the percentile, for example, when Mn is 4 mass%, Ni is 0 mass%, Si is 0.1 mass%, Cr is 0.2 mass%, As is 0 mass%, and W is 0 mass%, values when the formula is substituted are 4, 0, 0.1, 0.2, 0, and 0, respectively, whereby Ac 1-723.7 [ Mn%]－16.9[Ni％]+29.1[Si％]+16.9[Cr％]+290[As％]+6.38[W％]723-10.7 × 4-16.9 × 0+29.1 × 0.1+16.9 × 0.2+290 × 0+6.38 × 0 ═ 686.5. In addition, Ac3 ═ 910-]^1/2－15.2[Ni％]+44.7[Si％]+104[V％]+31.5[Mo％]+13.1[W％]Wherein C, Ni, Si, V, Mo and W each represents a mass percent thereof, and the values obtained by substituting the above-mentioned restriction formulas are values before the percentile, for example, when the mass percent of C is 0.12%, the mass percent of Ni is 0%, the mass percent of Si is 0.1%, the mass percent of V is 0.07%, the mass percent of Mo is 0.2%, and the mass percent of W is 0%, the values obtained by substituting the formulas are values, respectively, whereby Ac3 ═ 910-]^1/2－15.2[Ni％]+44.7[Si％]+104[V％]+31.5[Mo％]+13.1[W％]＝910－203×0.12^1/2－15.2×0+44.7×0.1+104×0.07+31.5×0.2+13.1×0＝857.7。

Further, in the manufacturing method of the present invention, in the step (3), the hot sizing temperature is 500-550 ℃.

Further, in the manufacturing method of the invention, in the step (1), the superheat degree of the molten steel is controlled to be less than or equal to 30 ℃ in the casting process.

Further, in the manufacturing method of the invention, in the step (2), the tube blank is soaked in the annular furnace with the temperature of 1180-1220 ℃, the perforation temperature is controlled to be 1140-1200 ℃, and the tension reducing temperature is controlled to be 880-930 ℃.

In the manufacturing method according to the present invention, in the step (2), in some embodiments, the raw pipe obtained in the step (1) may be cooled and then heated in an annular heating furnace.

Compared with the prior art, the high-strength expansion casing pipe and the manufacturing method thereof have the following beneficial effects:

(1) through reasonable component design, the high-strength expansion casing pipe disclosed by the invention is low in cost and has higher strength and elongation, so that the problems of low strength and poor plasticity after expansion of the expansion casing pipe in the prior art can be solved, the pressure resistance of the expansion casing pipe in underground use is improved, and the requirement of the oil field exploitation field on the high-strength expansion casing pipe is met.

(2) The manufacturing method of the high-strength expansion casing pipe ensures that the yield strength of the manufactured high-strength expansion casing pipe before expansion is 400-600MPa, the tensile strength is 700-950MPa, the yield ratio is less than or equal to 0.7, the elongation is more than or equal to 35 percent, the yield strength after 10-20 percent of expansion deformation reinforcement is 800-1000MPa, the tensile strength is 900-1100MPa, and the elongation is more than or equal to 15 percent through optimized process design.

(3) The manufacturing method of the high-strength expansion casing pipe is simple in process and easy to implement in mass production.

Detailed Description

The high strength expanded casing and the method of manufacturing the same according to the present invention will be further explained and illustrated in the following specific examples, which, however, should not be construed as unduly limiting the technical solution of the present invention.

Examples 1 to 5 and comparative examples 1 to 4

Tables 1 to 1 and tables 1 to 2 list the mass percentages of the respective chemical elements in the high strength expansion sleeves of examples 1 to 5 and comparative examples 1 to 4.

TABLE 1-1. (wt%, balance Fe and unavoidable impurities other than P, S, N)

Serial number	C	Mn	Si	P	S	Cr	Mo	V	Ac1	Ac1+30	Ac3	Ac3-30
													Example 1	0.1	3	0.2	0.009	0.002	/	/	0.05	697	727	860	830
Example 2	0.12	4	0.1	0.010	0.001	0.2	0.2	0.07	686	716	858	828
													Example 3	0.14	5	0.3	0.010	0.003	0.5	0.5	0.1	687	717	874	844
Example 4	0.18	6	0.4	0.012	0.005	/	/	0.15	670	700	857	827
													Example 5	0.20	4	0.25	0.013	0.002	/	/	0.2	687	717	851	821
Comparative example 1	0.1	1.5	0.2	0.009	0.002	/	/	0.05	713	743	860	830
													Comparative example 2	0.3	4	0.1	0.010	0.001	0.2	0.2	0.07	686	716	817	787
Comparative example 3	0.05	5	0.3	0.010	0.003	/	0.5	/	678	708	894	864
													Comparative example 4	0.18	6	0.4	0.012	0.005	/	/	0.15	670	700	857	827

Note: in the above table, Ac1 ═ 723-10.7 [ Mn% ]]－16.9[Ni％]+29.1[Si％]+16.9[Cr％]+290[As％]+6.38[W％]In the formula, Mn, Ni, Si, Cr, As, and W each represent their respective mass percentages, and the values when substituted into the above-defined formula should be substituted into the values before the percentile. Ac3 ═ 910-]^1/2－15.2[Ni％]+44.7[Si％]+104[V％]+31.5[Mo％]+13.1[W％]Wherein C, Ni, Si, V, Mo and W each represent a mass percentage of each thereof and are substituted for the above-mentioned limitsThe values in the formula should be substituted into the values before the percentile.

Tables 1-2 (wt%, balance Fe and inevitable impurities other than P, S, N)

The high strength expansion casings of examples 1-5 and comparative examples 1-4 were prepared using the following procedure (see tables 2-1 and 2-2 for specific process parameters):

(1) the method comprises the following steps of smelting in an electric furnace according to the mass percent of chemical elements in the table 1, performing impurity modification through Ca treatment after external refining, vacuum degassing and argon stirring to reduce the content of O, H, and continuously casting the alloy into a tube blank, wherein the superheat degree of molten steel is controlled to be less than or equal to 30 ℃ in the continuous casting process.

(2) Perforating and continuously rolling the tube blank: the tube blank is cooled and then soaked in an annular furnace at the temperature of 1180-.

(3) And (3) heat treatment: heating the steel pipe to an austenitizing temperature Ac1+30 ℃ to Ac3-30 ℃, preserving heat for 30-60min, and then performing water quenching; then tempering at the temperature of 650 plus 720 ℃ for 50-80 min; and then carrying out hot sizing at the temperature of 500-550 ℃. Wherein Ac1 is 723-10.7 [ Mn%]－16.9[Ni％]+29.1[Si％]+16.9[Cr％]+290[As％]+6.38[W％]Wherein Mn, Ni, Si, Cr, As and W each represent a mass percentage of each of them, and the values obtained by substituting the above-mentioned restriction formula are substituted into the values before the percentage, and Ac3 is 910-]^1/2－15.2[Ni％]+44.7[Si％]+104[V％]+31.5[Mo％]+13.1[W％]In the formula, C, Ni, Si, V, Mo, and W each represent their respective mass percentages, and the values when substituted into the above-defined formula should be substituted into the values before the percentile.

Tables 2-1 and 2-2 list specific process parameters of the manufacturing methods of the high strength expansion casings of examples 1-5 and comparative examples 1-4.

Table 2-1.

Table 2-2.

Table 3 shows the results of the performance test before expansion of the high strength expansion casings of examples 1 to 5 and comparative examples 1 to 4. Table 4 shows the results of the performance test of the high strength expansion sleeves of examples 1 to 5 and comparative examples 1 to 4 after the expansion deformation reinforcement of 10 to 20%.

Table 3.

Table 4.

As can be seen from tables 3 and 4, the yield strength of the high-strength expansion casing of examples 1-5 before expansion is 400-600MPa, the tensile strength is 700-950MPa, the yield ratio is less than or equal to 0.7, the elongation is more than or equal to 35%, and the transverse impact energy at 0 ℃ is more than 120J. The high strength expansion casing pipes of examples 1-5 have yield strength of 800-1000MPa, tensile strength of 900-1100MPa, elongation of 15% or more and transverse impact energy of 100J or more at 0 ℃ after 10-20% expansion deformation strengthening.

The high-strength expansion sleeve of comparative example 1 has an excessively low Mn content, and fails to obtain a granular bainite structure, and has a low strength after being strengthened by 10 to 20% expansion deformation.

The high-strength expansion sleeve of comparative example 2 had too high a C content, resulting in a decrease in plasticity.

The high strength expanded casing of comparative example 3 has no V added, has too low C content, and has strength less than 110 ksi.

The high-strength expansion sleeve of comparative example 4 has an austenitizing temperature that is not in the range of Ac1+30 c to Ac3-30 c during the manufacturing process, resulting in a reduction in plasticity.

It should be noted that the prior art in the protection scope of the present invention is not limited to the examples given in the present application, and all the prior art which is not inconsistent with the technical scheme of the present invention, including but not limited to the prior patent documents, the prior publications and the like, can be included in the protection scope of the present invention.

In addition, the combination of the features in the present application is not limited to the combination described in the claims of the present application or the combination described in the embodiments, and all the features described in the present application may be freely combined or combined in any manner unless contradictory to each other.

It should also be noted that the above-mentioned embodiments are only specific embodiments of the present invention. It is apparent that the present invention is not limited to the above embodiments and similar changes or modifications can be easily made by those skilled in the art from the disclosure of the present invention and shall fall within the scope of the present invention.

Claims

1. A high-strength expansion casing is characterized in that the high-strength expansion casing comprises the following chemical elements in percentage by mass:

2. The high strength expansion sleeve according to claim 1, wherein P is 0.015% or less, S is 0.005% or less, and N is 0.008% or less among the other inevitable impurities.

3. The high strength expanded casing according to claim 1, wherein the microstructure is ferrite + tempered sorbite + granular bainite.

4. The high strength expansion sleeve according to claim 3, wherein the area ratio of the granular bainite is 5 to 10%.

5. The high strength expansion sleeve according to claim 3, wherein the ferrite area ratio is 20-50%.

6. The high-strength expansion sleeve as claimed in claim 1, wherein the yield strength before expansion of the high-strength expansion sleeve is 400-600MPa, the tensile strength is 700-950MPa, the yield ratio is less than or equal to 0.7, and the elongation is greater than or equal to 35%.

7. The high-strength expansion sleeve as claimed in claim 1, wherein the yield strength of the high-strength expansion sleeve after 10-20% expansion deformation strengthening is 800-1000MPa, the tensile strength is 900-1100MPa, and the elongation is equal to or greater than 15%.

8. The method of manufacturing a high strength expanded casing according to any one of claims 1 to 7, comprising the steps of:

(1) smelting and continuously casting to obtain a tube blank;

(2) perforating and continuously rolling the tube blank;

9. The manufacturing method according to claim 8, wherein in the step (3), the hot sizing temperature is 500-550 ℃.

10. The manufacturing method according to claim 8, wherein in the step (1), the degree of superheat of the molten steel is controlled to be 30 ℃ or less during the casting.

11. The manufacturing method according to claim 8, wherein in the step (2), the tube blank is soaked in a 1180-1220 ℃ annular furnace, the perforation temperature is controlled to be 1140-1200 ℃, and the tension reducing temperature is controlled to be 880-930 ℃.