CN101413088B - Sulfurated hydrogen stress etching-resisting petroleum casing pipe and manufacturing method thereof - Google Patents

Abstract

The invention discloses a hydrogen sulfide stress-corrosion-resistant petroleum casing and a manufacturing method thereof, aiming at improving the purity of the steel, the yield strength ratio and the proportion of tempered martensite, refining grains, reducing residual stress, etc. Set out to provide an oil casing with high strength and toughness and hydrogen sulfide stress corrosion resistance and a manufacturing method thereof. The oil casing includes: C: 0.12-0.18%, Si: 0.10-0.60%, Mn: 0.05-1.0%, Cr: 0.20-1.0%, Mo: 0.10-0.80%, Al: 0.005-0.05%. , Ti: 0.005～0.02%, V: 0.05～0.15%, Nb: 0.002～0.02%, Ca: 0.0003～0.005%, Mg: 0.0003～0.005%, B: 0.0003～0.003%, P≤0.020%, N≤ 0.005%, the Fe of balance, wherein the weight percent of carbon, manganese, chromium, molybdenum is determined by comprehensive control formula A=C%+(Mn%/5)+(Cr%/5)+(Mo%/3), The range of A is 0.45-0.60%.

Description

Oil casing resistant to hydrogen sulfide stress corrosion and manufacturing method thereof

technical field

The invention belongs to the technical field of manufacturing seamless steel pipes in the metallurgical industry, and in particular relates to a hydrogen sulfide stress corrosion-resistant petroleum casing and a manufacturing method thereof.

Background technique

Hydrogen sulfide is contained in the oil and gas reservoirs of Sichuan, Changqing, North China and Xinjiang in my country, as well as the oil fields of Baroma in the United States and Pincher Bay in Canada. According to statistics, about 1/3 of the oil and gas fields in the world contain hydrogen sulfide gas. When ordinary oil casing is used in the exploitation of oil and gas resources containing hydrogen sulfide, under the joint action of stress and hydrogen sulfide gas, the oil casing will often suffer from brittle fracture suddenly when the stress is much lower than its yield strength. In the lighter case, the casing string or the entire well will be scrapped, and in the severe case, the hydrogen sulfide and oil gas will leak together, forming a blowout, which poses a great threat to the safe production of the oil and gas field.

In the future, with the increase of drilling depth in oil and gas fields, the use environment of oil casing will be more severe. Therefore, oil and gas field enterprises put forward higher requirements on the performance of oil casing. For this reason, the exploitation of oil and gas resources containing hydrogen sulfide gas must use high-quality oil casings with high strength and toughness that are resistant to hydrogen sulfide stress corrosion.

Oil casing pipes resistant to hydrogen sulfide corrosion require steel to have good strength, toughness and hydrogen sulfide corrosion resistance, but the toughness and hydrogen sulfide corrosion resistance of the material are affected by the form of carbides in the steel. In order to reduce the carbide on the metal lattice, it is necessary to reduce the carbon content of the alloy steel, but this will reduce the mechanical properties such as hardenability and yield strength of the material. For this reason, it is widely used to increase manganese (Mn), chromium (Cr) and molybdenum (Mo) content to improve the mechanical properties of the material such as hardenability and yield strength, and to improve the performance of hydrogen sulfide-resistant oil casing. However, due to the separate control of various alloying elements, it is easy to add excessive amounts of alloying elements, resulting in excessive equivalent carbon content, which reduces the plasticity and toughness of oil casings, and reduces the hydrogen sulfide stress corrosion resistance of steel.

In addition, in the high-strength oil casing, the density of lattice displacement increases, and hydrogen is easy to store at the lattice displacement, and further, hydrogen is easy to accumulate at the stress concentration site. Therefore, reasonable rolling and heat treatment process conditions are required to reduce residual stress and increase the yield ratio of the material.

Contents of the invention

The purpose of the present invention is to overcome the deficiencies in the prior art, starting from the aspects of improving the purity of the steel, the yield ratio and the proportion of tempered martensite, refining the grains, reducing the residual stress, etc., and providing a To meet the needs of deep oil and gas layer exploitation of hydrogen sulfide gas, an oil casing with high strength and toughness and hydrogen sulfide stress corrosion resistance and a manufacturing method thereof.

The present invention realizes through following technical scheme:

A petroleum casing resistant to hydrogen sulfide stress corrosion, characterized in that it is composed of the following components by weight percentage: C: 0.12-0.18%, Si: 0.10-0.60%, Mn: 0.05-1.0%, Cr: 0.20- 1.0%, Mo: 0.10-0.80%, Al: 0.005-0.05%, Ti: 0.005-0.02%, V: 0.05-0.15%, Nb: 0.002-0.02%, Ca: 0.0003-0.005%, Mg: 0.0003-0.005% %, B: 0.0003～0.003%, P≤0.020%, S≤0.005%, N≤0.005%, the balance of Fe, wherein the weight percentage of carbon, manganese, chromium and molybdenum is determined by the comprehensive control formula A=C%+( Mn%/5)+(Cr%/5)+(Mo%/3) determined, where A is the comprehensive content of carbon, manganese, chromium and molybdenum, the range of A is 0.45-0.60%, carbon, manganese, chromium , The content of molybdenum is not only within the range of comprehensive content, but also within the range of respective content.

The role of the main alloying elements is:

C: Carbon is a carbide forming element that can increase the strength and hardness of steel. When the carbon content is less than 0.1%, in order to obtain the desired strength, tempering must be carried out at low temperature. This low-temperature tempering treatment results in low hydrogen sulfide stress corrosion resistance. And when the carbon content exceeds 0.2%, the yield ratio decreases, and the desired yield strength is obtained. As the carbon content increases, the hardness increases and the hydrogen sulfide stress corrosion resistance decreases. In order to obtain a balance between hardness and hydrogen sulfide stress corrosion resistance, the carbon content range is controlled between 0.12% and 0.18%.

Si: Silicon has a reducing effect and can also be used to improve the hardenability and strength of steel. When the silicon content is less than 0.05%, the effect is not obvious, but when the silicon content exceeds 1.0%, the hydrogen sulfide stress corrosion resistance will be reduced. Therefore, the content range of silicon is controlled between 0.1% and 0.6%.

Mn: Manganese is an austenite-forming element, which can improve the hardenability and strength of steel, increase the amount of retained austenite in steel, and affect the uniformity of hot-rolled structure. Generally, the content of 0.05% or more is required, but once the manganese content exceeds 1.0%, the ability to resist hydrogen sulfide stress corrosion will decrease. Therefore, the content of manganese is generally controlled within the range of 0.05-1.00%.

Cr: Chromium can improve the mechanical properties, corrosion resistance and hardenability of steel, so that the effective content is above 0.05%, but if the chromium content exceeds 1.5%, the hydrogen sulfide stress corrosion resistance of steel will be reduced. Therefore, the content of chromium is generally controlled in the range of 0.20-1.00%.

Mo: Molybdenum can improve the hardenability of steel and ensure the high strength of steel, and at the same time can improve the hydrogen sulfide stress corrosion resistance of steel. The content of molybdenum to exert its effect is more than 0.05%, but if the content of molybdenum exceeds 1.0%, coarse carbides will be formed at the austenite grain boundaries, which will reduce the ability to resist hydrogen sulfide stress corrosion. Therefore, the content of molybdenum is generally controlled within the range of 0.10-0.80%.

Al: Aluminum has a reducing effect and can improve the toughness and workability of steel. When the content of aluminum exceeds 0.10%, the probability of defects on the metal surface increases. Therefore, the content of aluminum is generally controlled within the range of 0.005-0.05%.

Ti: Titanium, as a nitride, combines with nitrogen in the steel, allowing boron to exist in a solid solution state during quenching, and has the effect of improving the quenching performance. In order to obtain this effect of titanium, the content of titanium needs to be 0.002% or more. However, when the content of titanium exceeds 0.05%, it exists as coarse nitrides, which reduces the resistance to sulfide stress corrosion. Therefore, the content of titanium is controlled within the range of 0.005-0.02%.

V: When vanadium is tempered, it can refine grains, form carbides, and improve the strength and toughness of steel. When the content of vanadium exceeds 0.03%, it can fully function; but when the content of vanadium exceeds 0.20%, the toughness decreases. Therefore, the content of vanadium is controlled within the range of 0.05-0.15%.

Nb: Niobium forms carbonitrides at high temperatures to prevent coarsening of crystals and improve hydrogen sulfide stress corrosion resistance. When the content of niobium exceeds 0.002%, it can play a role, but when the content of niobium exceeds 0.04%, the carbonitride is too coarse, which reduces the hydrogen sulfide stress corrosion resistance on the contrary. Therefore, the content of niobium is controlled within the range of 0.002-0.020%.

Ca: Calcium reacts with sulfur in steel to form sulfide, improves the form of sulfur element, and improves the hydrogen sulfide stress corrosion resistance of steel. When the calcium content exceeds 0.0003%, it can play a role, but when the calcium content exceeds 0.005%, the content of intervening substances in the steel increases, the purity of the steel decreases, and instead reduces the hydrogen sulfide stress corrosion resistance. Therefore, the calcium content is controlled within the range of 0.0003-0.005%.

Mg: Magnesium reacts with sulfur in steel to form sulfide, which improves the form of sulfur element and improves the hydrogen sulfide stress corrosion resistance of steel. When the magnesium content exceeds 0.0003%, it can play a role, but when the magnesium content exceeds 0.005%, the content of intervening substances in the steel increases, the purity of the steel decreases, and instead reduces the hydrogen sulfide stress corrosion resistance. Therefore, the content of magnesium is controlled within the range of 0.0003-0.005%.

B: Boron can improve the hardenability of steel with the content of impurities. In order to obtain a significant effect, the content of boron needs to exceed 0.0003%, but when the content of boron exceeds 0.005%, the toughness of the steel will decrease. For this reason, the boron content is controlled within the range of 0.0003-0.003%.

P: Phosphorus is an impurity in steel, which will cause grain segregation and reduce toughness, especially if the content exceeds 0.025%, the hydrogen sulfide stress corrosion resistance will drop sharply. Therefore, the content of phosphorus is controlled below 0.020%.

S: Sulfur is an impurity in steel, and if its content exceeds 0.010%, the hydrogen sulfide stress corrosion resistance will be significantly reduced. Therefore, the content of sulfur is controlled below 0.005%.

N: Nitrogen combines with aluminum, titanium, niobium and other elements to form nitrides. If the nitrogen content is too high, it will not only lead to coarse grains of aluminum nitride and titanium nitride, but also form nitrides with boron, which will significantly reduce the hardenability. Therefore, the nitrogen content is controlled below 0.005%.

In order to have high strength and toughness and hydrogen sulfide stress corrosion resistance, the manufacturing method of the petroleum casing pipe of the present invention, the rolling process is that the tube blank is heated and pierced at 1100-1050 °C, the final rolling temperature of continuous rolling is not lower than 950 °C, and the rolling process is constant. The final rolling temperature of the diameter rolling is not lower than 900°C, and the characteristic is that: the blank pipe that has completed the fixed reduction rolling is cooled to below the Ar3 critical temperature on the cooling bed, and then the heat treatment process of quenching and tempering is adopted, and the quenching medium is water-based quenching liquid, the quenching temperature is 950°C±10°C, the tempering temperature is 670-710°C, and air cooling is used. After heat treatment, the oil casing pipe undergoes secondary thermal sizing and thermal straightening treatment. The secondary thermal sizing temperature is between 550 and 600 °C, and the thermal straightening temperature is between 500 °C and 540 °C.

Specific steps are as follows:

(1) Ingredients smelting

Sponge iron and scrap steel are used as raw materials for steelmaking, melted into molten steel by electric arc eccentric furnace (EFA), and then subjected to external refining (LF) and vacuum (VD) degassing methods to control the content of impurities in the steel and improve the purity of the steel. The weight components of the obtained oil casing are: C: 0.12-0.18%, Si: 0.10-0.60%, Mn: 0.05-1.0%, Cr: 0.20-1.0%, Mo: 0.10-0.80%, Al: 0.005-0.05% , Ti: 0.005～0.02%, V: 0.05～0.15%, Nb: 0.002～0.02%, Ca: 0.0003～0.005%, Mg: 0.0003～0.005%, B: 0.0003～0.003%, P≤0.020%, S≤ 0.005%, N≤0.005%, and the balance is iron.

(2) Continuous casting and rolling

The above-mentioned high-purity molten steel is continuously cast into a round billet, and the cooled continuous casting billet is put into an annular heating furnace for heating. ℃, the final rolling temperature of continuous rolling is not lower than 950 ℃, the final rolling temperature of fixed diameter reduction is not lower than 900 ℃, cooling and sawing.

The following describes the role of each manufacturing process:

Ring furnace:

Heating temperature of tube billet: 1160～1210℃, allowable temperature difference: ±5℃, and the furnace temperature reaches 1160℃.

In order to improve the temperature control accuracy, the annular heating furnace is divided into 7 control areas along the circumferential direction, the preheating section occupies one control area, the heating section occupies four control areas, the soaking section occupies one control area, and the discharge section occupies one control area Among them, the temperature of the preheating section is 540±20°C, the temperature of the heating section is 1210±5°C, the temperature of the soaking section is 1210±5°C, and the heating curve of the steel pipe is a parabola with a progressive 1160°C.

Centering and perforation process:

Using thermal centering and Mannesmann perforation to reduce the perforation shear strain of alloy steel, prevent cracks, folds, delamination and other defects on the surface of the capillary, ensure the geometric size and shape accuracy of the capillary, and heat centering temperature 1110～1150℃, the piercing temperature is 1050～1110℃.

Continuous rolling process:

The purpose of the continuous rolling process is to reduce the diameter, extend and reduce the wall of the capillary tube transferred from the piercing process, and at the same time improve the roughness of the inner and outer surfaces of the blank tube and improve the uniformity of the wall thickness. Continuous rolling adopts limit-moving mandrel rolling to control the reduction of each roll of the continuous rolling mill to ensure the accuracy of the tube billet.

When the temperature of continuous rolling is lower than 800°C, the deformation resistance of the capillary is too large, causing the problem of tool wear. On the other hand, when the continuous rolling temperature is higher than 1100°C, the metal grains are too coarse, and the hydrogen sulfide stress corrosion resistance is reduced. Therefore, the rolling temperature is controlled between 950 and 1100°C.

Fixed diameter reduction process:

The sizing and reducing process is a process of continuous rolling of hollow bodies. In addition to the role of sizing, a large diameter reduction rate is generally required. Generally, the total diameter reduction rate is controlled within the range of 10-25%. The number of stands of the three-high sizing and reducing mill is 24, and the final rolling temperature is controlled at not lower than 900°C.

Cooling bed cooling:

A cooling bed is set behind the sizing and reducing rolling unit, so that the blank tube after sizing and reducing rolling enters the cooling bed, and is cooled to 10 ℃ ~ 40 ℃ below the critical temperature of Ar3 to refine the grain, and then directly sent to the heat treatment Reheating furnaces to save energy through in-line heat treatment.

(3) Tube processing

The heat treatment process of tempering after quenching is adopted, the quenching temperature is 950°C±10°C, the quenching medium is water-based quenching liquid, the tempering temperature is 670-710°C, and air cooling is adopted. After the heat treatment of the blank pipe, it needs to undergo secondary sizing and straightening treatment. The temperature of the sizing machine is between 550-600°C, the temperature of heat straightening is between 500°C-540°C, and the final flaw detection.

Quenching process:

The blank pipe after sizing and reducing rolling directly enters the cooling bed set behind the sizing and reducing rolling mill, and is air-cooled on the cooling bed to 10°C to 40°C below the critical temperature of Ar3. After sawing, it is loaded into the cooling bed set behind the cooling bed The heating furnace is heated to the temperature range from the critical point of Ac 3 to 1000°C. When the heating temperature is lower than the Ac 3 critical point temperature, iron oxide will be formed, and a uniform quenched structure cannot be obtained; and when the heating temperature exceeds 1000°C, the grain growth will be promoted, and the coarse grains will lead to hydrogen sulfide resistance. Reduced stress corrosion performance. The purpose of this heating is to eliminate the temperature difference in the length direction of the steel pipe and homogenize the structure. Determine the heating temperature of the blank tube at 950°C±10°C, keep it warm for 10 minutes to fully form austenite, and use water-based quenching liquid as the quenching medium to ensure a cooling rate of 20°C/s to obtain sufficient martensite structure.

Tempering process:

Tempering is carried out below the critical temperature of Ac 1 to fully obtain the tempered martensite structure, so that the steel pipe has a high yield ratio and improves the high hydrogen sulfide stress corrosion resistance of the seamless steel pipe.

The tempering temperature is controlled between 670°C and 710°C, and the tempering time is related to the wall thickness of the steel pipe, and it takes about 20 to 60 minutes.

Secondary sizing process:

Choose reasonable sizing parameters, and the diameter deformation rate of secondary sizing reaches 3% to 5%, so that a certain residual compressive stress will be generated on the surface of the oil casing, the mechanical properties of the oil casing will be improved, and the size and quality of the oil casing will be improved. Roundness accuracy.

The secondary sizing temperature is controlled within the range of 550-600°C.

Thermal straightening process:

Choose the best straightening reduction coefficient, reduce the residual stress produced by the straightening process, improve the roundness and straightness of the oil casing, and improve the performance of the oil casing. The straightening reduction coefficient is generally 0.64 to 0.77 times the elastic limit deformation of the seamless steel pipe.

The heat straightening temperature is between 500°C and 540°C.

The oil casing with high strength and toughness produced by the method of the invention has a yield strength above 862MPa, an ultimate strength ≥ 894MPa, and a yield ratio ≥ 90%.

The indicators achieved by the mechanical properties of the oil casing are as follows:

Yield strength: 862～931MPa

Ultimate strength: 894.2～1012.0Mpa

Yield ratio: 92～96.4%

Threshold value of hydrogen sulfide stress corrosion resistance measured by NACE TM 0177-96A method: 90-95% SMYS

Residual stress: ≤150MPa

Geometric Dimensions of Oil Casing

Error range of diameter: 0.995% Dmm ~ 1.01% Dmm

Out of roundness: ≤1.1mm

Wall thickness: ≤-8.0%t～8.0%t

Straightness: pipe end ≤ 1.5mm/m, pipe body ≤ 1.5‰

The present invention has following technical effect:

In the steel grade design of the oil casing pipe of the present invention, the weight percentage of carbon, manganese, chromium, molybdenum is controlled by the comprehensive control formula A=C%+(Mn%/5)+(Cr%/5)+(Mo%/3 ) determined that by comprehensively controlling the content of carbon, manganese, chromium and molybdenum, the strength, hardenability, hardness, plasticity and toughness of oil casing can be improved. At the same time, titanium, vanadium and niobium alloy elements are added to improve the quenching performance and refine the grain structure. By optimizing the composition content of the alloy steel, the ability of the oil casing to resist hydrogen sulfide corrosion is improved.

The production method of the oil casing pipe of the present invention, through the ultra-pure steel smelting technology, reduces the sulfur, phosphorus and other impurities and gas content in the steel; adopts the method of combining rolling and heat treatment to refine the austenite grain; adopts strict Heat treatment process to obtain uniform microstructure and tempered martensite microstructure and yield strength ratio, so as to obtain alloy steel with excellent hydrogen sulfide stress corrosion resistance.

Detailed ways

The present invention will be described in detail below in conjunction with specific examples.

Example 1

The specific process of manufacturing oil casing with a size of 244.5×11.99mm is as follows:

Sponge iron and scrap steel are used as raw materials for steelmaking, and melted into molten steel in an electric arc furnace. After refining outside the furnace and vacuum degassing, the chemical composition of the molten steel obtained is: C: 0.15%, S: 0.15%, Mn: 0.76 %, Cr: 0.35%, Mo: 0.40%, Al: 0.025%, Ti: 0.016%, V: 0.070%, Nb: 0.005%, Ca: 0.0018%, Mg: 0.0015%, B: 0.0013%, P: 0.010 %, S: 0.002%, N: 0.0034%, and the balance is iron. The A value is 0.5053%.

The above-mentioned high-purity molten steel is continuously cast into a round billet. The cooled continuous casting slab is heated in the annular heating furnace, the heating temperature of the tube blank is 1190 ℃, the heat centering temperature is 1120 ℃, and the Mannesmann method is used for hot piercing, limited mandrel rolling and reducing rolling , the final rolling temperature of continuous rolling is not lower than 950°C, and the final sizing and reducing rolling temperature is controlled at 920°C, which is above the critical temperature of Ar3. The blank pipes after sizing and reducing rolling directly enter the cooling bed behind the sizing and reducing rolling unit, and are air-cooled to below the Ar3 critical temperature of 800-820°C to refine the grains. After sawing, the cooled raw pipe is directly sent to the reheating furnace for heat treatment, heated to 950°C for 10 minutes, and then quenched and heat treated. The quenching medium is water-based quenching liquid, and the cooling rate is 20°C/s. Uniform heating at 680°C for 30 minutes for tempering. Secondary thermal sizing at 560°C,

The diameter deformation rate of secondary sizing is controlled at about 3.8%. Heat straightening at 520°C, and finally flaw detection to get the finished oil casing.

The mechanical properties of the casing obtained are as follows:

Yield strength: 923Mpa

Ultimate strength: 997Mpa

Yield ratio: 92.6%

Threshold value of hydrogen sulfide stress corrosion resistance measured by NACE TM 0177-96A method: 91% SMYS

Residual stress: 112.37MPa

Geometric Dimensions of Oil Casing

Diameter range: 245.64(D+0.46%D)mm～246.19(D+0.69%D)mm

Out of roundness: ≤0.6mm

Wall thickness: ≤-4.5%t～7.0%t

Straightness: pipe end ≤ 1.2mm/m, pipe body ≤ 1.1‰.

Example 2

The specific process of manufacturing oil casing with a size of 244.5×11.99mm is as follows:

Sponge iron and scrap steel are used as raw materials for steelmaking, melted into molten steel in an electric arc furnace, and after refining outside the furnace and vacuum degassing, the chemical composition of the molten steel obtained is: C: 0.14%, Si: 0.32%, Mn: 0.66 %, Cr: 0.41%, Mo: 0.71%, Al: 0.025%, Ti: 0.013%, V: 0.12%, N: 0.0041%, Nb: 0.005%, Ca: 0.0013%, Mg: 0.00185%, B: 0.0012 %, P: 0.008%, S: 0.001%, N: 0.0027%, and the balance is iron. The A value is 0.5907%.

The above-mentioned high-purity molten steel is continuously cast into a round billet. The cooled continuous casting slab is heated in the annular heating furnace, the heating temperature of the tube blank is 1190°C, the heat centering temperature is 1140°C, and the Mannesmann method is used for hot piercing, limited mandrel rolling and reducing rolling , the final rolling temperature of continuous rolling is not lower than 950°C, and the final sizing and reducing rolling temperature is controlled at 920°C, which is above the critical temperature of Ar3. The blank tubes after sizing and reducing rolling directly enter the cooling bed behind the sizing and reducing rolling unit, and are air-cooled to below the Ar3 critical temperature of 810-830°C to refine the grains. After sawing, the cooled raw pipe is directly sent to the reheating furnace for heat treatment, heated to 950°C for 10 minutes, and then quenched and heat treated. The quenching medium is water-based quenching liquid, and the cooling rate is 20°C/s. Uniform heating at 690°C for 30 minutes for tempering. At 560°C for secondary thermal sizing, the diameter deformation rate of the secondary sizing is controlled at 3.6%. Heat straightening at 520°C, and finally flaw detection to get the finished oil casing.

The mechanical properties of the casing obtained are as follows:

Yield strength: 891MPa

Ultimate strength: 926Mpa

Yield ratio: 96.2%

Threshold value of hydrogen sulfide stress corrosion resistance measured by NACE TM 0177-96A method: 95% SMYS

Residual stress: 107.59Mpa

Geometric Dimensions of Oil Casing

Diameter range: 244.77mm(D+0.11%D)～246.23mm(D+0.77%D)

Out of roundness: ≤0.6mm

Wall thickness: ≤-4.5%t～7.0%t

Straightness: pipe end ≤ 1.2mm/m, pipe body ≤ 1.1‰

Example 3

The specific process of manufacturing oil casing with a size of 244.5×11.99mm is as follows:

Sponge iron and scrap steel are used as raw materials for steelmaking, melted into molten steel in an electric arc furnace, and after refining outside the furnace and vacuum degassing, the chemical composition of the molten steel obtained is: C: 0.13%, Si: 0.37%, Mn: 0.71 %, Cr: 0.38%, Mo: 0.49%, Al: 0.021%, Ti: 0.018%, V: 0.10%, Nb: 0.0045%, Ca: 0.0027%, Mg: 0.0025%, B: 0.0019%, P: 0.007 %, S: 0.001%, N: 0.0012%, and the balance is iron. The A value is 0.5113%.

The above-mentioned high-purity molten steel is continuously cast into a round billet. The cooled continuous casting slab is heated in the annular heating furnace, the heating temperature of the tube blank is 1190°C, the heat centering temperature is 1140°C, and the Mannesmann method is used for hot piercing, limited mandrel rolling and reducing rolling , the final rolling temperature of continuous rolling is not lower than 950°C, and the final sizing and reducing rolling temperature is controlled at 920°C, which is above the critical temperature of Ar3. The blank tubes after sizing and reducing rolling directly enter the cooling bed behind the sizing and reducing rolling unit, and are air-cooled to below the Ar3 critical temperature of 810-830°C to refine the grains. After sawing, the cooled raw pipe is directly sent to the reheating furnace for heat treatment, heated to 950°C for 10 minutes, and then quenched and heat treated. The quenching medium is water-based quenching liquid, and the cooling rate is 20°C/s. Uniform heating at 700°C for 30 minutes for tempering. At 560°C for secondary heat sizing, the diameter deformation rate of the secondary sizing is controlled at 4.1%. Heat straightening at 520°C, and finally flaw detection to get the finished oil casing.

The mechanical properties of the casing obtained are as follows:

Yield strength: 875MPa

Ultimate strength: 928Mpa

Yield ratio: 94.3%

Threshold value of hydrogen sulfide stress corrosion resistance measured by NACE TM 0177-96A method: 95% SMYS

Residual stress: 107.59Mpa

Geometric Dimensions of Oil Casing

Diameter range: 245.71(D+0.49%D)mm～246.76(D+0.92%D)mm

Out of roundness: ≤0.6mm

Wall thickness: ≤-4.5%t～7.0%t

Straightness: pipe end ≤ 1.2mm/m, pipe body ≤ 1.1‰

Claims (3)

1. the manufacture method of the petroleum casing pipe of a sulfurated hydrogen stress etching-resisting is characterized in that, comprises the steps:

(1) batching is smelted

Adopt sponge iron and steel scrap to do steelmaking feed, be fused into molten steel with the eccentric stove of electric arc, through external refining and vacuum outgas method, the content of impurity in the control steel, improve the purity of steel, the molten steel composition that obtains the manufacturing petroleum casing pipe is by weight percentage: C:0.12～0.18%, Si:0.10～0.60%, Mn:0.05～1.0%, Cr:0.20～1.0%, Mo:0.10～0.80%, Al:0.005～0.05%, Ti:0.005～0.02%, V:0.05～0.15%, Nb:0.002～0.02%, Ca:0.0003～0.005%, Mg:0.0003～0.005%, B:0.0003～0.003%, P≤0.020%, S≤0.005%, N≤0.005%, surplus are iron; Wherein the weight percent of carbon, manganese, chromium, molybdenum determines that by Comprehensive Control formula A=C%+ (Mn%/5)+(Cr%/5)+(Mo%/3) A is the comprehensive content of carbon, manganese, chromium, molybdenum in the formula, and the weight percent of A is 0.45-0.60%;

(2) continuous casting and rolling

Above-mentioned high purity steel water continuous casting is become the circle base, and with the cooled continuously cast bloom rotary heating furnace internal heating of packing into, the heating of pipe blank temperature is 1160～1210 ℃, afterwards, hot centering, hot piercing, tandem rolling, decides tube reducing; Wherein, heat centering temperature is 1110～1150 ℃, and hot piercing temperature is 1050～1110 ℃, and the finishing temperature of tandem rolling is not less than 950 ℃, and the finishing temperature of deciding tube reducing is not less than 900 ℃.

(3) pipe processing

In the back of deciding the reducing and rolling unit cold bed is set, the hollow forging of deciding behind the reducing and rolling directly enters cold bed, and is air-cooled to below the Ar3 critical temperature 10 ℃～40 ℃, crystal grain thinning; Directly send into heat treated reheating furnace after the cooled hollow forging sawing, be heated to 950 ℃ ± 10 ℃, carry out quenching heat treatment, be incubated 10 minutes, quenchant is the water-based hardening liquid, and speed of cooling is 20 ℃/second; Carry out tempering heat treatment after the quenching, tempering temperature is 670～710 ℃, adopts air cooling; After the hollow forging thermal treatment, handle through secondary sizing and hot straightening, flaw detection obtains the finished product petroleum casing pipe at last, and wherein, secondary sizing temperature is between 550～600 ℃, and the hot straightening temperature is between 500 ℃～540 ℃.

2. the manufacture method of the petroleum casing pipe of sulfurated hydrogen stress etching-resisting according to claim 1 is characterized in that, the diameter distortion rate of secondary sizing is 3%～5%.

3. the manufacture method of the petroleum casing pipe of sulfurated hydrogen stress etching-resisting according to claim 1 is characterized in that, the telescopic geometric accuracy satisfies following requirement: the limit of error of diameter: 0.995%～1.01%D, and wherein, D is a diameter; Out of roundness :≤1.1mm, wall thickness :≤-8.0%t～8.0%t, straight degree: pipe end≤1.5mm/m, body≤1.5 ‰.