CN109112427B - High-strength high-toughness non-quenched and tempered steel pipe for geological drilling and manufacturing method thereof - Google Patents
High-strength high-toughness non-quenched and tempered steel pipe for geological drilling and manufacturing method thereof Download PDFInfo
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/38—Ferrous alloys, e.g. steel alloys containing chromium with more than 1.5% by weight of manganese
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21C—MANUFACTURE OF METAL SHEETS, WIRE, RODS, TUBES OR PROFILES, OTHERWISE THAN BY ROLLING; AUXILIARY OPERATIONS USED IN CONNECTION WITH METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL
- B21C37/00—Manufacture of metal sheets, bars, wire, tubes or like semi-manufactured products, not otherwise provided for; Manufacture of tubes of special shape
- B21C37/06—Manufacture of metal sheets, bars, wire, tubes or like semi-manufactured products, not otherwise provided for; Manufacture of tubes of special shape of tubes or metal hoses; Combined procedures for making tubes, e.g. for making multi-wall tubes
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/10—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of tubular bodies
- C21D8/105—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of tubular bodies of ferrous alloys
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/22—Ferrous alloys, e.g. steel alloys containing chromium with molybdenum or tungsten
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/26—Ferrous alloys, e.g. steel alloys containing chromium with niobium or tantalum
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/32—Ferrous alloys, e.g. steel alloys containing chromium with boron
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/002—Bainite
Abstract
The invention discloses a high-strength high-toughness non-quenched and tempered steel pipe for geological drilling, which comprises the following chemical elements in percentage by mass: c: 0.05-0.15%, Si: 0.5-1%, Mn: 1.6-2.5%, Cr: 0.2-1%, Mo: 0.2-0.8%, B: 0.001 to 0.005%, Al: 0.01 to 0.08%, Nb: 0.01-0.06%, less than or equal to 0.008% of N, and the balance of Fe and other inevitable impurities. In addition, the invention also discloses a manufacturing method of the high-strength high-toughness non-quenched and tempered steel pipe for geological drilling, which comprises the following steps: (1) preparing a tube blank; (2) manufacturing the tube blank into a pierced billet; (3) rolling the steel pipe; (4) and air cooling after rolling. The high-strength high-toughness non-quenched and tempered steel pipe for geological drilling has the tensile strength of more than or equal to 1000MPa, and the full-size impact power KV2 of more than or equal to 80J at 0 ℃, and is suitable for deeper geological drilling.
Description
Technical Field
The present invention relates to a steel pipe and a method for manufacturing the same, and more particularly to a steel pipe for geological drilling and a method for manufacturing the same.
Background
With the continuous exploitation and consumption of mineral resources, shallow mineral resources are gradually reduced, and geological exploration work develops towards deeper strata. At present, the geological exploration depth is gradually increased from tens of meters to hundreds of meters to more than 1500 meters and even 2000 meters, the deeper depth and more complex formation conditions provide more severe performance requirements for the applied geological drilling pipe, and the pipe column of the drilling pipe bears complex loads such as tension, compression, torsion, bending, vibration and the like, and simultaneously faces the combined action of various complex factors such as friction, corrosive media and the like of the formation. Generally speaking, the strength of the pipe is increased, the load capacity such as tensile, pressure and torsion resistance can be effectively improved, and the wear resistance can be improved by improving the hardness. However, the high-strength material needs to have enough toughness matching to effectively resist the expansion of surface micro-defects and the fatigue problem caused by alternating load.
At present, the grades of the commonly used drilling pipes in China are DZ40, DZ50 and DZ60 in YB/T standard, R780 in JIS G3465 and the like, the highest grade is the grade of tensile strength 830MPa, the requirement of deep hole drilling can not be met obviously at present, and higher-grade drilling pipe products need to be developed.
In recent years, some high-strength drill pipe products adopting quenching and tempering heat treatment are developed by some domestic manufacturers, the tensile strength can reach the level of 900 plus 1000MPa, but after the quenching and tempering heat treatment, on one hand, the ovality of the pipe becomes worse, which brings adverse effects to subsequent thread processing, on the other hand, part of drilling tool manufacturers generally adopt a mode of processing threads after the pipe end is thickened to increase the connection strength, and the pipe end needs to be heated to high temperature during thickening, and the material cannot maintain the high strength of the quenching and tempering state after being austenitized again, so that the quenched and tempered pipe is not suitable for subsequent thickening. Therefore, it is necessary to develop a drill pipe product with high strength and high toughness without hardening and tempering to meet the demand of deep geological drilling.
Chinese patent publication No. CN102994895A, published as 3.2013 and 27.2013 entitled "steel for micro-alloying geological drilling with high strength and high toughness" and its production process discloses a steel for micro-alloying geological drilling with high strength and high toughness and its production process. In the technical scheme disclosed in the patent document, the main principle is that microalloy elements are added on the basis of carbon-manganese steel for strengthening, the tensile strength grade of the steel is only 750MPa at most, and the requirement of deep drilling cannot be met.
Chinese patent publication No. CN104532168A, published as 2015, 4, and 22, entitled "high-quality non-quenched and tempered seamless steel pipe for drilling and method for manufacturing the same", discloses a high-quality non-quenched and tempered seamless steel pipe for drilling and method for manufacturing the same, having a strength of 1100MPa or more, using a bainite structure design, however, in the technical solution disclosed in the patent document, the design principle is medium-high carbon Mn — Mo bainite steel.
Disclosure of Invention
One of the purposes of the invention is to provide a high-strength high-toughness non-quenched and tempered steel pipe for geological drilling, which is added based on Mn-Mo-B-Nb alloy, can obtain a bainite structure with uniform high strength under an austenite air cooling condition, and simultaneously adopts a reasonable component low-carbon system to be matched with an air cooling speed, so that a high-strength fine-grained bainite structure can be obtained under the austenite air cooling condition, thereby ensuring that the high-strength high-toughness non-quenched and tempered steel pipe for geological drilling has high strength and high toughness.
In order to achieve the purpose, the invention provides a high-strength high-toughness non-quenched and tempered steel pipe for geological drilling, which comprises the following chemical elements in percentage by mass:
c: 0.05-0.15%, Si: 0.5-1%, Mn: 1.6-2.5%, Cr: 0.2-1%, Mo: 0.2-0.8%, B: 0.001 to 0.005%, Al: 0.01 to 0.08%, Nb: 0.01-0.06%, less than or equal to 0.008% of N, and the balance of Fe and other inevitable impurities.
Through the relation research on the material components, the structure and the performance, the inventor discovers that: by adopting a mode of low C and high Mn and adding proper amount of alloy elements such as Cr, Mo, B and the like, on one hand, the stability of austenite can be increased, pearlite transformation is delayed, namely, hardenability is increased, on the other hand, the Ms point can be reduced, the tendency of transformation from undercooled austenite to martensite is reduced, and the obtained steel pipe can be subjected to air cooling to obtain a microstructure mainly comprising bainite and high toughness.
Based on the above findings, the inventors of the present invention designed the chemical elements of the high-strength high-toughness non-quenched and tempered steel pipe according to the present invention, and the design principle is as follows:
c: in the high-strength high-toughness non-quenched and tempered steel pipe for geological drilling, C is beneficial to improving the strength of steel, but can also reduce the ductility and toughness of the steel, in addition, the C can also improve the Ms point and increase the tendency of the steel to form martensite, and in order to ensure the toughness and toughness matching of the steel and maintain the bainite structure, the mass percent of C in the high-strength high-toughness non-quenched and tempered steel pipe for geological drilling is limited to 0.05-0.15%.
Si: in the high-strength high-toughness non-quenched and tempered steel pipe for geological drilling according to the present invention, Si is an element introduced by a deoxidizer in the steel, and is advantageous for transformation of austenite to bainite in the steel, so that it is necessary to maintain the mass percentage of Si at 0.5% or more, but when the mass percentage of Si exceeds 1%, the cold brittleness tendency of the steel is significantly increased. In the high-strength high-toughness non-quenched and tempered steel pipe for geological drilling, the mass percent of Si is limited to 0.5-1.0%.
Mn: in the high-strength high-toughness non-quenched and tempered steel pipe for geological drilling, Mn has the beneficial effects of expanding an austenite phase region, increasing hardenability, refining grains and the like, when the mass percent of C is limited to a lower level (for example, the mass percent of C is 0.05-0.15%), enough Mn needs to be added to improve the solid solution strengthening effect, and meanwhile, after the mass percent of Mn exceeds 2.5%, the hot workability of the steel can be obviously influenced. Therefore, in the technical scheme of the invention, the mass percent of Mn is limited to 1.6-2.5%.
Cr: cr is a strong carbide forming element, dispersion precipitation strengthening of carbide in the phase change process is an important material strengthening mechanism, and usually more than 0.2 percent of Cr needs to be added to have an obvious effect. However, if the amount of the additive is too large, coarse carbides are formed, and the toughness of the material is lowered. Therefore, in the technical scheme of the invention, the mass percent of Cr is limited to 0.2-1%.
Mo: in the high-strength high-toughness non-quenched and tempered steel pipe for geological drilling, Mo strongly delays the transformation from supercooled austenite to pearlite, so that the transformation is very favorable for forming a structure mainly comprising bainite, and meanwhile Mo has a good solid solution strengthening effect and is favorable for improving the performance of the steel. Therefore, based on the requirements of structure and performance control, more than 0.2 mass% of Mo needs to be added. In addition, too high a mass percentage of Mo tends to form coarse carbide precipitates, which are detrimental to the toughness of the steel, and therefore the Mo content needs to be limited to 0.8% or less. Therefore, the mass percentage of Mo in the high-strength high-toughness non-quenched and tempered steel pipe for geological drilling is limited to 0.2-0.8.
B: in the technical scheme of the invention, B can strongly increase the stability of the super-cooled austenite of the steel, thereby increasing the transformation tendency of bainite, the effect can be obviously achieved by adding B with the mass percent of more than 0.001%, and when the mass percent of B exceeds 0.005%, nitrides which are not beneficial to the toughness of the steel are easily precipitated at the position of a crystal boundary, so that in the high-strength high-toughness non-quenched and tempered steel pipe for geological drilling, the mass percent of B is controlled to be 0.001-0.005%.
Al: in the technical scheme, Al is an element necessary for steel deoxidation, so that the introduction cannot be completely avoided, but the mass percent of Al exceeds 0.1%, so that the casting process and the like are adversely affected, and therefore, the mass percent of Al of the high-strength high-toughness non-quenched and tempered steel pipe for geological drilling is controlled to be 0.01-0.08%, preferably 0.01-0.05%.
Nb: according to the research of the inventor, the precipitation temperature (such as 1000 ℃) of Nb in microalloy elements is most favorable for refining the bainite structure in the invention, more than 0.01 percent of Nb is required to obtain obvious effect, and in addition, after the mass percent of Nb exceeds 0.06 percent, coarse carbide is easily formed, thereby being not favorable for the plastic toughness of the steel. Therefore, the mass percent of Nb in the high-strength high-toughness non-quenched and tempered steel pipe for geological drilling needs to be controlled to be 0.01-0.06%.
N: in the high-strength high-toughness non-quenched and tempered steel pipe for geological drilling, N is added into the steel to effectively improve the strength and the hardness of the steel, but the N is easily combined with B to form boron nitride, so that the characteristic that B increases bainite transformation tendency in the steel is eliminated, and therefore, the mass percent of N in the high-strength high-toughness non-quenched and tempered steel pipe for geological drilling is controlled to be less than or equal to 0.008 percent.
S: s is a harmful element in steel, and its presence adversely affects corrosion resistance, hot workability, toughness, etc. of steel, so that it is necessary to limit the mass percentage of S to 0.01% or less, preferably 0.005% or less.
P: p is a harmful element in steel, the presence of which adversely affects the corrosion resistance, toughness, etc. of steel, and therefore it is necessary to limit the mass percentage of P to 0.03% or less, and preferably to control the mass percentage of P to 0.02% or less.
O: o exists in steel as various oxide inclusions, the existence of the inclusions has adverse effects on the hot workability and the ductility and toughness of the steel, and in order to ensure the final performance, the mass percent of O needs to be controlled to be lower than 0.008 percent.
Further, in the high-strength high-toughness non-quenched and tempered steel pipe for geological drilling, related chemical elements also meet the following requirements: mn +6Mo is more than or equal to 3.2, wherein Mn and Mo respectively represent the mass percent. This is because: the inventor finds that Mn +6Mo is more than or equal to 3.2 on the basis of the control of the elements, and the structure proportion of granular bainite can be effectively ensured, so that the toughness of the steel is improved.
The values of Mn and Mo when substituted are the numbers before the percentage, that is, when the mass percentage of Mn is 2.1% and the mass percentage of Mo is 0.28%, for example, the arithmetic expression is 2.1+6 × 0.28 — 3.78 ≧ 3.2.
Further, in the high-strength high-toughness non-quenched and tempered steel pipe for geological drilling, related chemical elements also meet the following requirements: Al/N is more than or equal to 2, wherein Al and N respectively represent the mass percent of the alloy. The Al/N is controlled to be more than or equal to 2, which is beneficial to solidifying the N element as much as possible.
The values of Al and N when substituted are the values before the percentile, that is, for example, when the mass percentage of Al is 0.02% and the mass percentage of N is 0.004%, the arithmetic expression is 0.02/0.004, that is, 5 ≧ 2.
Further, in the high-strength high-toughness non-quenched and tempered steel pipe for geological drilling according to the present invention, the microstructure thereof is mainly composed of bainite, the phase ratio of the bainite is 90% or more, and the ratio of granular bainite in the bainite structure is 60% or more.
Further, in the high-strength high-toughness non-quenched and tempered steel pipe for geological drilling, the grain size is above grade 8.
Furthermore, the tensile strength of the high-strength high-toughness non-quenched and tempered steel pipe for geological drilling is more than or equal to 1000MPa, and the 0 ℃ full-size impact energy KV2 is more than or equal to 80J.
Another object of the present invention is to provide a method for manufacturing the above-mentioned high-strength high-toughness non-quenched and tempered steel pipe for geological drilling, by which the obtained steel pipe can have high toughness only by simple controlled cooling without quenching and tempering heat treatment. In addition, the manufacturing method has simple production flow, and does not have the problems of ovality increase, poor straightness and the like caused by quenching and tempering heat treatment. Meanwhile, the product is also suitable for a subsequent pipe end upsetting and thickening type geological drill rod production method, and high strength and toughness can be obtained through air cooling after the pipe end is thickened.
In order to achieve the purpose, the invention provides a manufacturing method of the high-strength high-toughness non-quenched and tempered steel pipe for geological drilling, which comprises the following steps of:
(1) preparing a tube blank;
(2) manufacturing the tube blank into a pierced billet;
(3) rolling the steel pipe: the rolling temperature is not lower than 800 ℃, so that the structure after finish rolling is a fully austenitic structure;
(4) and air cooling after rolling.
In the above scheme, the low rolling temperature causes precipitation of proeutectoid ferrite, thereby lowering the toughness of the obtained steel pipe.
Further, in the manufacturing method of the present invention, in the step (2), the raw pipe is heated to 1150 to 1300 ℃ and kept for 1 to 4 hours, and then pierced, continuously rolled, reduced in tension or sized in tension to obtain a pierced pipe.
In the above scheme, the heating temperature is not lower than 1150 ℃ to ensure sufficient deformability, and the heating temperature is controlled to be lower than 1300 ℃ to prevent overburning.
Further, in the manufacturing method of the present invention, in the step (4), the average cooling rate is 10 ℃/min to 120 ℃/min, and when the cooling rate is lower than 10 ℃/min, the transformation tends to equilibrium transformation due to low supercooling degree, and more pro-eutectoid ferrite soft phases are generated, thereby affecting the toughness of the steel, whereas when the cooling rate is higher than 120 ℃/min, brittle martensite phases are generated, thereby affecting the toughness of the steel.
According to the research on Mn-Mo-B bainite steel, the steel pipe for high-strength high-toughness non-quenched and tempered geological drilling can obtain a high-strength fine-grained bainite structure under an austenite air cooling condition based on Mn-Mo-B-Nb alloy addition and by adopting a reasonable component system and matching with an air cooling rate, the grain size reaches more than 8 grades, wherein the main body of a microstructure is bainite, the phase proportion of the bainite is more than 90%, and the proportion of granular bainite in the bainite structure is more than 60%. Therefore, the high-strength high-toughness non-quenched and tempered steel pipe for geological drilling can obtain enough strength and toughness matching. The tensile strength of the obtained high-strength high-toughness non-quenched and tempered steel pipe for geological drilling is more than or equal to 1000MPa, and the full-size impact power KV2 at 0 ℃ is more than or equal to 80J, so that the high-strength high-toughness non-quenched and tempered steel pipe for geological drilling is suitable for deeper geological drilling.
In addition, the high-strength high-toughness non-quenched and tempered steel pipe for geological drilling can obtain a bainite structure with a high proportion in a wide cooling speed range, has stable performance and can be used for manufacturing pipe materials with large wall thickness.
In addition, the manufacturing method does not need quenching and tempering heat treatment after rolling, can obtain the steel pipe with high strength and toughness only through simple air cooling, has simpler production flow, and does not have the problems of ovality increase, poor straightness and the like caused by quenching and tempering heat treatment. Meanwhile, the product is also suitable for a subsequent pipe end upsetting and thickening type geological drill rod production method, and high strength and toughness can be obtained through air cooling after the pipe end is thickened.
Drawings
Fig. 1 is a metallographic structure diagram of a high-strength high-toughness non-quenched and tempered steel pipe for geological drilling according to example 1.
Detailed Description
The high strength and high toughness non-quenched and tempered geological drilling steel pipe and the manufacturing method thereof according to the present invention will be further explained and illustrated with reference to the drawings and specific examples, which, however, should not be construed to unduly limit the technical solution of the present invention.
Examples 1 to 6 and comparative examples 1 to 4
Table 1 lists the mass percentages of the respective chemical elements in the high strength and high toughness non-quenched and tempered steel pipes for examples 1 to 6 and the conventional steel pipes for comparative examples 1 to 4.
Table 1 (wt%, balance Fe and inevitable impurity elements other than P, S, O)
The manufacturing methods of the high strength and high toughness non-quenched and tempered steel pipes for examples 1 to 6 and the conventional steel pipes for comparative examples 1 to 4 include the steps of:
(1) casting into ingots according to the chemical element components listed in Table 1 to prepare tube blanks;
(2) manufacturing the tube blank into a pierced billet: heating the tube blank to 1150-1300 ℃, keeping for 1-4 hours, and then performing perforation, continuous rolling, tension reducing or tension sizing to obtain a pierced billet;
(3) rolling the steel pipe: the rolling temperature is not lower than 800 ℃, so that the structure after finish rolling is a fully austenitic structure;
(4) air cooling after rolling: the average cooling speed is 10-120 ℃/min.
Table 2 lists specific process parameters in the manufacturing methods of the high strength and high toughness non-quenched and tempered steel pipe for example 1 to 6 and the conventional steel pipe for comparative example 1 to 4.
The data in table 2 are specifically determined:
the yield strength data is obtained by processing the manufactured steel pipe into an API arc-shaped sample, and averaging after testing according to the API standard;
the data of the full-size Charpy V-shaped impact absorption energy is obtained by taking a semi-size V-shaped impact sample with the sectional area of 5 x 10 x 55 on a manufactured steel pipe, and averaging the V-shaped impact sample after the V-shaped impact sample is tested according to GB/T229 standard;
the metallographic structure proportion is obtained by taking a full-wall-thickness sample from a sample tube, grinding and polishing the sample tube, corroding the sample tube by using 4% nitric acid and ethanol, photographing the sample tube under a metallographic microscope, and counting the sample tube by using optical software.
The time taken for complete cooling to room temperature was carried out using a thermocouple burying test.
Table 2.
The high strength and high toughness non-quenched and tempered steel pipes of examples 1 to 6 and the conventional steel pipes of comparative examples 1 to 4 were subjected to performance measurement, and the results thereof are shown in table 3.
TABLE 3
| Numbering | Tensile Strength Rm (MPa) | 0 ℃ full size impact work (J) |
| Example 1 | 1020 | 97 |
| Example 2 | 1080 | 134 |
| Example 3 | 1145 | 123 |
| Example 4 | 1116 | 168 |
| Example 5 | 1139 | 176 |
| Example 6 | 1082 | 128 |
| Comparative example 1 | 915 | 76 |
| Comparative example 2 | 726 | 42 |
| Comparative example 3 | 770 | 34 |
| Comparative example 4 | 1196 | 21 |
As can be seen from Table 3, the tensile strength of the high-strength high-toughness non-quenched and tempered steel pipe for geological drilling in each example is not less than 1000MPa, and the 0 ℃ full-scale impact energy KV2 is not less than 80J.
As can be seen from tables 1 to 3, the conventional steel pipes of comparative examples 1 to 3 cannot obtain sufficient toughness because the chemical element component ratios of the present case are not adopted in comparative examples 1, 2 and 3; in addition, the finishing temperature of the comparative example 3 is too low, so that proeutectoid ferrite is precipitated, and the toughness is reduced; in contrast, in comparative example 4, the chemical element component ratio is adopted, but too much lath bainite or even martensite structure is generated due to too high cooling rate in the manufacturing process, and the toughness of the conventional steel pipe in comparative example 4 is reduced.
Fig. 1 is a metallographic structure diagram of a high-strength high-toughness non-quenched and tempered steel pipe for geological drilling according to example 1.
As can be seen from fig. 1, the steel pipe for high-strength high-toughness non-quenched and tempered geological drilling of example 1 has a microstructure mainly composed of bainite, a phase ratio of the bainite is 90% or more, a grain size of the bainite in the bainite structure is 60% or more, and a grain size is 8 or more.
It should be noted that the above-mentioned embodiments are only specific examples of the present invention, and obviously, the present invention is not limited to the above-mentioned embodiments, and many similar variations exist. All modifications which would occur to one skilled in the art and which are, therefore, directly derived or suggested from the disclosure herein are deemed to be within the scope of the present invention.
Claims (5)
1. A high-strength high-toughness non-quenched and tempered steel pipe for geological drilling is characterized by comprising the following chemical elements in percentage by mass:
c: 0.05-0.15%, Si: 0.5-1%, Mn: 1.6-2.5%, Cr: 0.2-1%, Mo: 0.2-0.8%, B: 0.001 to 0.005%, Al: 0.01 to 0.08%, Nb: 0.01-0.06%, less than or equal to 0.008% of N, and the balance of Fe and other inevitable impurities;
the high-strength high-toughness non-quenched and tempered steel pipe for geological drilling is characterized in that the microstructure of the steel pipe is mainly bainite, the phase proportion of the bainite is more than 90%, and the proportion of granular bainite in the bainite structure is more than 60%;
wherein the relevant chemical elements also satisfy: mn +6Mo is more than or equal to 3.2, wherein Mn and Mo respectively represent the mass percent of the alloy; Al/N is more than or equal to 2, wherein Al and N respectively represent the mass percent of the alloy.
2. A high strength high toughness non-quenched and tempered steel pipe for geological drilling as claimed in claim 1, wherein the grain size is at least 8 grade.
3. The steel pipe for high-strength high-toughness non-quenched and tempered geological drilling as claimed in claim 1, wherein the tensile strength is not less than 1000MPa, and the 0 ℃ full-scale impact energy KV2 is not less than 80J.
4. A method of manufacturing a high strength high toughness non heat treated steel pipe for geological drilling as claimed in any of claims 1-3, comprising the steps of:
(1) preparing a tube blank;
(2) manufacturing the tube blank into a pierced billet;
(3) rolling the steel pipe: the rolling temperature is not lower than 800 ℃, so that the structure after finish rolling is a fully austenitic structure;
(4) air cooling after rolling: the average cooling speed is 10-120 ℃/min.
5. The manufacturing method according to claim 4, wherein in the step (2), the pierced blank is obtained by piercing, continuous rolling, tension reducing or tension sizing after heating the pierced blank to 1150 to 1300 ℃ for 1 to 4 hours.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201710495540.5A CN109112427B (en) | 2017-06-26 | 2017-06-26 | High-strength high-toughness non-quenched and tempered steel pipe for geological drilling and manufacturing method thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201710495540.5A CN109112427B (en) | 2017-06-26 | 2017-06-26 | High-strength high-toughness non-quenched and tempered steel pipe for geological drilling and manufacturing method thereof |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN109112427A CN109112427A (en) | 2019-01-01 |
| CN109112427B true CN109112427B (en) | 2021-05-14 |
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| CN101967604A (en) * | 2010-11-05 | 2011-02-09 | 钢铁研究总院 | Boron-nitrogen composite microalloyecd steel allowing for high heat input welding and manufacturing method |
| CN103614629A (en) * | 2013-12-12 | 2014-03-05 | 钢铁研究总院 | 900MPa grade hot rolling non-tempering thin steel sheet and preparation method thereof |
| CN105986200A (en) * | 2015-01-31 | 2016-10-05 | 重庆麦卡瑞机械制造有限公司 | Novel non-quenched and tempered steel |
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| JP3969328B2 (en) * | 2003-03-26 | 2007-09-05 | 住友金属工業株式会社 | Non-tempered seamless steel pipe |
| CN1210430C (en) * | 2003-08-01 | 2005-07-13 | 清华大学 | Medium-low carbon manganese system self-hardening bainite steel |
| JP6361278B2 (en) * | 2014-05-16 | 2018-07-25 | 新日鐵住金株式会社 | Manufacturing method of rolled steel |
| CN105907937A (en) * | 2016-04-26 | 2016-08-31 | 宝山钢铁股份有限公司 | Manufacturing method for bainite high-strength seamless steel tube and bainite high-strength seamless steel tube |
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| CN101967604A (en) * | 2010-11-05 | 2011-02-09 | 钢铁研究总院 | Boron-nitrogen composite microalloyecd steel allowing for high heat input welding and manufacturing method |
| CN103614629A (en) * | 2013-12-12 | 2014-03-05 | 钢铁研究总院 | 900MPa grade hot rolling non-tempering thin steel sheet and preparation method thereof |
| CN105986200A (en) * | 2015-01-31 | 2016-10-05 | 重庆麦卡瑞机械制造有限公司 | Novel non-quenched and tempered steel |
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| 1000MPa低碳贝氏体钢的连续冷却转变组织及力学性能;易敏等;《钢铁》;20130215;全文 * |
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