CN114836681A - High-strength seamless steel pipe with good fatigue resistance and manufacturing method thereof - Google Patents
High-strength seamless steel pipe with good fatigue resistance and manufacturing method thereof Download PDFInfo
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- 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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- 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
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/18—Hardening; Quenching with or without subsequent tempering
- C21D1/25—Hardening, combined with annealing between 300 degrees Celsius and 600 degrees Celsius, i.e. heat refining ("Vergüten")
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- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/26—Methods of annealing
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- 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
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/26—Methods of annealing
- C21D1/28—Normalising
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- 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
- C21D6/00—Heat treatment of ferrous alloys
- C21D6/002—Heat treatment of ferrous alloys containing Cr
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- 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
- C21D6/00—Heat treatment of ferrous alloys
- C21D6/005—Heat treatment of ferrous alloys containing Mn
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- 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
- C21D6/00—Heat treatment of ferrous alloys
- C21D6/008—Heat treatment of ferrous alloys containing Si
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- 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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- 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
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/08—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for tubular bodies or pipes
- C21D9/085—Cooling or quenching
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- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/001—Ferrous alloys, e.g. steel alloys containing N
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- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
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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
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
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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
- 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
- C21D2211/005—Ferrite
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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
- C21D2211/009—Pearlite
Abstract
The invention discloses a high-strength seamless steel pipe with good fatigue resistance, which comprises the following chemical elements in percentage by mass besides Fe and inevitable impurities: c: 0.28-0.38%, Si is less than or equal to 0.35%, Mn: 0.5-1.0%, Cr: 0.6 to 1.6%, Mo: 0.1-0.35%, N: 0.0035-0.0085%, Al: 0.020-0.055%, Ca: 0.0005 to 0.005%. In addition, the invention also discloses a manufacturing method of the high-strength seamless steel pipe, which comprises the following steps: (1) preparing a tube blank; (2) heating, perforating, hot rolling and sizing to obtain a hot-rolled pipe; (3) intermediate heat treatment; (4) cold drawing or cold rolling; (5) normalizing or annealing heat treatment.
Description
Technical Field
The invention relates to a seamless steel tube and a manufacturing method thereof, in particular to a high-strength seamless steel tube and a manufacturing method thereof.
Background
In recent years, with the tightening of environmental regulations and policies in China, the requirements of markets and users on energy conservation and emission reduction of automobiles are higher and higher, in order to achieve the maximum light weight, in addition to the main body of the automobile made of high-strength steel and light materials, automobile parts with smaller occupation in the weight of the whole automobile, such as driving shaft products, are also brought into weight reduction lines, and hollow pipes replace solid bars and forged materials.
Parts such as a drive shaft for an automobile are important safety parts because they have a function of transmitting engine torque to drive wheels. Since the drive shaft is required to receive an extremely large torsional moment, as well as a traction force, a braking force, etc. from the wheels, and the received forces include a longitudinal force, a lateral force, a vertical force, a shock impact force, etc., the material is required to have strong strength and plasticity to ensure sufficient fatigue resistance. In addition, with the improvement of living standard of people, higher and higher demands are also put forward on the comfort level of the automobile in the driving process, so that the material design needs to consider the material rigidity and the like while considering the light weight so as to improve the anti-seismic property of the automobile and achieve the effect of noise reduction.
Therefore, the traditional mode of producing the automobile driving shaft by friction stir welding is gradually replaced by new processes such as cold die forging and the like, the whole body is processed into a special shape which is more favorable for noise reduction and has expanded diameter and thinned middle and reduced diameter and thickened two ends, and the processing of the end part spline is favorable, so that the hollow steel pipe material also needs to have good cold processing performance.
Chinese patent publication No. CN104962838A, published as 10/2015 and 7/2015, entitled "a high-strength steel, high-strength plastic seamless steel tube for automobile transmission half-shaft and manufacturing method thereof", discloses a high-strength plastic seamless steel tube, which comprises the following chemical components: c: 0.07 to 0.15%, Si: 0.1 to 1.0%, Mn: 2.0-2.6%, Ni: 0.05-0.6%, Cr: 0.2 to 1.0%, Mo: 0.1-0.6%, B: 0.001-0.006 percent of Cu, 0.05-0.50 percent of Cu; 0.015-0.060% of Al; 0.02 to 0.1 percent of Nb; 0.02-0.15% of V, the steel pipe is in low C design, has low strength, is beneficial to welding and is more suitable for the automobile half shaft produced by friction stir welding.
Chinese patent publication No. CN1950532A, published as 4/18/2007, entitled "seamless steel pipe and method for manufacturing same", discloses a seam steel pipe and method for manufacturing same, which comprises the following chemical components in percentage by mass: c: 0.30-0.50%, Si is less than or equal to 0.50%, Mn: 0.3-2.0%, P is less than or equal to 0.025%, S is less than or equal to 0.005%, Cr: 0.15 to 1.0 percent of Al, 0.001 to 0.050 percent of Al; ti: 0.005-0.05%, N is less than or equal to 0.02%, B is 0.0005-0.01%, O is less than or equal to 0.0050%; and Beff is more than or equal to 0.0001: wherein a) when Neff is N-14 xTi/47.9 ≧ 0, Beff is B-10.8(N-14 xTi/47.9)/14; b) when Neff is N-14 × Ti/47.9<0, Beff is b. The invention uses high C, Mn and Cr and controls the proportion of Ti/B/N to achieve high strength and hardenability, but the problems of quenching cracks, grinding cracks and the like easily occur in the quenching and tempering process due to the excessively high C.
Based on the above, aiming at the defects and shortcomings in the prior art, the invention expects to obtain the high-strength seamless steel tube with good fatigue resistance, and the high-strength seamless steel tube not only has good room-temperature mechanical property, cold processing property and good anti-torsion fatigue life, but also has excellent toughness, and can be effectively suitable for parts such as automobile driving shafts and the like which bear high-strength torsion loads.
Disclosure of Invention
One of the purposes of the invention is to provide a high-strength seamless steel tube with good fatigue resistance, which not only has good room-temperature mechanical property, cold processing property and good anti-torsion fatigue life, but also has excellent toughness, no crack occurs in the cold processing process, no crack occurs in the quenching and tempering process, and the high-strength seamless steel tube is especially suitable for parts such as automobile driving shafts and the like which bear high-strength torsion loads, and has very wide application prospect.
In order to achieve the above object, the present invention proposes a high-strength seamless steel pipe excellent in fatigue resistance, which contains, in addition to Fe and inevitable impurities, the following chemical elements in mass percent:
C：0.28～0.38％，Si≤0.35％，Mn：0.5～1.0％，Cr：0.6～1.6％，Mo：0.1～0.35％，N：0.0035～0.0085％,Al：0.020～0.055％,Ca：0.0005～0.005％。
further, in the high-strength seamless steel pipe with good fatigue resistance of the invention, the mass percentages of the chemical elements are as follows:
c: 0.28-0.38%, Si more than 0 and less than or equal to 0.35%, Mn: 0.5-1.0%, Cr: 0.6-1.6%, Mo: 0.1-0.35%, N: 0.0035-0.0085%, Al: 0.020-0.055%, Ca: 0.0005 to 0.005%; the balance being Fe and unavoidable impurities.
In the high-strength seamless steel pipe with good fatigue resistance of the present invention, the design principle of each chemical element is specifically as follows:
c: in the high-strength seamless steel pipe with good fatigue resistance, the improvement of the content of the C element is beneficial to the improvement of the material strength and the fatigue resistance, but the content of the C element in the steel is not too high, so that the toughness and the plasticity of the steel are reduced when the content of the C element in the steel is too high, cold working is not facilitated, processing cracks are easy to occur, and decarburization control is difficult. Therefore, in order to ensure the quenching hardness and the hardenability of the material, the quenching crack sensitivity and the cold working performance, the mass percentage content of C in the high-strength seamless steel pipe with good fatigue resistance is controlled to be 0.28-0.38%.
Of course, in certain preferred embodiments, in order to obtain better implementation effect, the mass percentage content of C may be preferably controlled to be between 0.31 and 0.36%.
Si: in the high-strength seamless steel pipe with good fatigue resistance, Si is a residual element of steel after smelting and deoxidation. In the present invention, the content of Si element in steel should be reduced as much as possible, and the lower the content of Si element in steel, the better the cold workability of the material. Therefore, in the high-strength seamless steel pipe with good fatigue resistance, the mass percentage of Si is controlled to be less than or equal to 0.35 percent.
Of course, in certain preferred embodiments, the Si element may be preferably controlled to have a mass percentage of Si less than or equal to 0.25% in order to achieve better performance.
Mn: in the high-strength seamless steel pipe with good fatigue resistance, the Mn element content is increased, which is beneficial to improving the material strength, and the Mn element can effectively stabilize the impurity element P, S, avoid the formation of low-melting-point sulfide, and improve the hot-working performance of the material. The content of Mn element in steel should not be too low, and when the content of Mn element in steel is low, P, S element cannot be stabilized well, and the required effect cannot be achieved. In addition, it should be noted that the content of Mn element in steel should not be too high, and too high content of Mn element in steel can cause severe cold working deformation hardening, which aggravates die wear. Based on the above, in the high-strength seamless steel pipe with good fatigue resistance, the mass percentage of Mn is controlled to be 0.5-1.0%.
Of course, in some preferred embodiments, in order to obtain better implementation effect, the mass percentage content of Mn may be preferably controlled between 0.55 and 0.95%.
Cr: in the high-strength seamless steel pipe with good fatigue resistance, the Cr element content is increased, so that the hardenability of the material is improved, the strength and the fatigue resistance of the material are improved, and the strength and the toughness of the material are ensured by matching with the C and Mo contents. Therefore, in the high-strength seamless steel pipe with good fatigue resistance, the mass percentage of Cr is controlled to be 0.6-1.6%.
Of course, in some preferred embodiments, the content of Cr may be preferably controlled to be between 0.80 and 1.20% by mass in order to obtain better practical effects.
Mo: in the high-strength seamless steel pipe with good fatigue resistance, Mo has a solidification strengthening effect, the strength and the tempering stability of the steel can be improved, and the Mo and the C can ensure the strength and the toughness of the material by matching, so that the anti-torsional fatigue capability of the material is improved. Therefore, in the high-strength seamless steel pipe with good fatigue resistance, the content of Mo is controlled to be 0.1-0.35% by mass. Of course, in some preferred embodiments, the content of Mo may be preferably controlled to be between 0.15 and 0.30% by mass in order to obtain better performance.
N: in the high-strength seamless steel pipe with good fatigue resistance, the N element can effectively improve the strength and the low-temperature toughness of the steel, but the content of the N element in the steel is not high, and when the content of the N element in the steel is too high, the appearance of N compounds is easy to be included. Therefore, in the high-strength seamless steel pipe with good fatigue resistance, the content of N in percentage by mass is controlled to be 0.0035-0.0085%.
Of course, in certain preferred embodiments, in order to achieve better implementation effect, the mass percentage of N may be preferably controlled to be between 0.0045 and 0.0065%.
Al, Ca: in the high-strength seamless steel pipe excellent in fatigue resistance according to the present invention, both the Al element and the Ca element are elements added to the steel for deoxidation. In the invention, Si is a residual element of steel after smelting deoxidation, and in order to ensure that the steel only contains lower Si content, the O removal mode in the molten steel smelting process needs to be changed, so that the deoxidation level needs to be ensured by comprehensively controlling the Al and Ca contents, and the corresponding nonmetallic inclusion does not have adverse effect on the anti-fatigue performance. Based on the above, in the high-strength seamless steel pipe with good fatigue resistance, the content of the Al element is controlled to be 0.020-0.055% by mass, and the content of the Ca element is controlled to be 0.0005-0.005% by mass.
Of course, in some preferred embodiments, in order to obtain better implementation effect, it may be preferable to control the mass percentage of Al to be between 0.025 and 0.045%, and the mass percentage of Ca to be between 0.001 and 0.004%.
Further, in the high-strength seamless steel pipe with good fatigue resistance of the present invention, the mass percentage of each chemical element satisfies at least one of the following:
C：0.31～0.36％，
Si≤0.25％，
Mn：0.55～0.95％，
Cr：0.80～1.20％，
Mo：0.15～0.30％，
N：0.0045～0.0065％,
Al：0.025～0.045％,
Ca：0.001～0.004％。
furthermore, in the high-strength seamless steel pipe with good fatigue resistance, P is less than or equal to 0.015 percent, S is less than or equal to 0.008 percent, and O is less than or equal to 0.0035 percent in inevitable impurities.
In the above technical solutions, P, S and O are inevitable impurity elements in steel, and the content of the impurity elements in the steel should be reduced as much as possible in order to obtain a steel with better performance and better quality when the technical conditions allow. In the invention, P, S element in steel is steel raw and auxiliary materials or impurity element introduced in the production process, P element can embrittle the grain boundary and deteriorate the toughness and the processing performance of the material, and S element can form sulfide with low melting point and reduce the processing performance and the mechanical performance of the material.
Further, in the high-strength seamless steel pipe excellent in fatigue resistance according to the present invention, the microstructure thereof is ferrite + sorbite.
Further, in the high-strength seamless steel pipe excellent in fatigue resistance according to the present invention, the semi-decarburized depth from the outer wall surface inward in the wall thickness direction is not more than 120 μm.
Further, the high-strength seamless steel pipe having excellent fatigue resistance of the present invention has a diameter of 30 to 55mm and/or a wall thickness of 3.0 to 5.5 mm.
Further, in the high-strength seamless steel pipe excellent in fatigue resistance of the present invention, the properties before the heat treatment for quenching and tempering satisfy: yield strength rp 0.2: 300-450MPa, tensile strength Rm not less than 450MPa, elongation A 50 ≥22％。
Further, in the high-strength seamless steel pipe excellent in fatigue resistance according to the present invention, the performance after the quenching and tempering heat treatment satisfies at least one of the following: the yield strength Rp0.2 is more than or equal to 1200MPa, the tensile strength Rm is more than or equal to 1700MPa, and the elongation percentage A 50 Not less than 8%, the fatigue life under high input torque is not less than 3000 times, the fatigue life under medium input torque is not less than 30000 times, and the fatigue life under low input torque is not less than 1000000 times.
Correspondingly, the invention also aims to provide a manufacturing method of the high-strength seamless steel tube with good fatigue resistance, the manufacturing method is simple to produce, and the obtained high-strength seamless steel tube not only has good room-temperature mechanical property, cold processing property and good torsional fatigue resistance life, but also has excellent toughness, no crack in the cold processing process, and no crack in the quenching and tempering process, is particularly suitable for parts such as automobile driving shafts and the like which bear high-strength torsional loads, and has good popularization prospect and application value.
In order to achieve the above object, the present invention provides a method for manufacturing a high-strength seamless steel pipe having excellent fatigue resistance, comprising the steps of:
(1) preparing a tube blank;
(2) heating, perforating, hot rolling and sizing to obtain a hot-rolled pipe;
(3) intermediate heat treatment;
(4) cold drawing or cold rolling;
(5) normalizing or annealing heat treatment.
In the above technical solution of the present invention, in order to ensure that the high-strength seamless steel pipe manufactured by the above manufacturing method has excellent properties and meets the requirements of the pipe size precision of the automobile driving shaft and the surface state in the cold die forging process, after the hot-rolled pipe obtained in the above step (2), the obtained hot-rolled pipe may be further subjected to intermediate heat treatment, acid pickling lubrication, cold drawing or cold rolling to a desired specification and size precision, and then further subjected to normalizing or annealing heat treatment.
Further, in the manufacturing method, in the step (2), the heating temperature is 1180-1300 ℃, and then the temperature is kept for 2-6 hours.
Further, in the manufacturing method of the present invention, in the step (2), the piercing temperature is 950 to 1250 ℃.
In the technical scheme, the tube blank is controlled to be heated and insulated at 1180-1300 ℃ for 2-6 hours in the step (2) of the manufacturing method, so that the tube blank can be effectively ensured to have good thermoplasticity. Correspondingly, high-temperature deformation such as high-temperature perforation, hot rolling and sizing and the like is controlled between 950 ℃ and 1250 ℃, so that the deformation defect can be controlled.
Further, in the manufacturing method of the invention, in the step (3), annealing is carried out at a temperature of 680-900 ℃, and heat preservation is carried out for 0.25-3 h.
In the technical scheme, the hot rolled pipe needs to be subjected to intermediate heat treatment in the step (3), annealing is carried out at the temperature of 680-900 ℃, and heat preservation is carried out for 0.25-3 hours. This operation is performed to ensure that the cold drawing or cold rolling process of the subsequent step (4) is smoothly performed.
Further, in the manufacturing method, in the step (5), the normalizing or annealing temperature is 700-880 ℃, the heat preservation time is 0.5-3 h, and then air cooling or air cooling is carried out.
In the technical scheme, the cold-drawn or cold-rolled pipe material is normalized or annealed at the temperature of 700-880 ℃, the heat is preserved for 0.5-3 h, the atmosphere of an annealing furnace is controlled, so that the prepared high-strength seamless steel pipe is ensured not to be subjected to full decarburization, the semi-decarburization depth is less than or equal to 120 mu m, the ferrite and sorbite structure is ensured to be obtained through the matching of the normalizing temperature and the cooling mode, and the high-strength seamless steel pipe with the strength and the toughness meeting the cold die forging processing requirements is ensured to be obtained.
Further, the manufacturing method also comprises the steps of (6) quenching and tempering and quenching heat treatment, wherein the quenching temperature is 880-920 ℃, the heat preservation time is 0.5-2 min, and then water cooling is carried out; tempering temperature is 150-300 ℃, heat preservation time is 20-40 min, and then air cooling is carried out.
Compared with the prior art, the high-strength seamless steel pipe with good fatigue resistance and the manufacturing method thereof have the advantages and beneficial effects as follows:
in the invention, the high-strength seamless steel pipe with good fatigue resistance can be obtained by reasonably optimizing and designing chemical components and matching with a manufacturing process, and the high-strength seamless steel pipe not only has good room-temperature mechanical property and cold processing property, but also has good torsional fatigue resistance life.
The performance of the high-strength seamless steel pipe with good fatigue resistance produced by the invention before quenching and tempering heat treatment meets the following requirements: yield strength rp 0.2: 300-450MPa, tensile strength Rm not less than 450MPa, elongation A 50 Not less than 22 percent; the performance after quenching and tempering heat treatment meets the following requirements: the yield strength Rp0.2 is more than or equal to 1200MPa, the tensile strength Rm is more than or equal to 1700MPa, and the elongation percentage A 50 More than or equal to 8 percent, the fatigue life under high input torque (input torque 2000N.m) is more than or equal to 3000 times, the fatigue life under medium input torque (input torque 1200N.m) is more than or equal to 30000 times, and the fatigue life under low input torque (input torque 800N.m) is more than or equal to 1000000 times. The high-strength seamless steel pipe has no cracks in the cold machining process and no cracks in the quenching and tempering process, is particularly suitable for parts such as automobile driving shafts and the like which bear high-strength torsional loads, and has very wide application prospect.
Drawings
FIG. 1 schematically shows hardenability test curves measured by holding high-strength seamless steel pipes of examples 7 and 8 at 900 ℃ for 40 min.
FIG. 2 is a microstructure morphology photograph of the high strength seamless steel tube of example 9 at one viewing angle.
FIG. 3 is a microstructure morphology photograph of the high strength seamless steel tube of example 9 at another viewing angle.
Detailed Description
The high strength seamless steel pipe with excellent fatigue resistance and the manufacturing method thereof according to the present invention will be further explained and explained with reference to the specific examples and drawings of the specification, however, the explanation and explanation should not be construed as an undue limitation on the technical solution of the present invention.
Examples 1 to 15 and comparative examples 1 to 5
The high-strength seamless steel pipes with good fatigue resistance of examples 1 to 15 and the comparative seamless steel pipes of comparative examples 1 to 5 were each produced by the following procedure:
(1) according to the chemical compositions shown in the following table 1, a pipe blank is produced by smelting and refining casting in an electric furnace or a converter, and then is cut by continuous casting to obtain a pipe blank of a desired size.
(2) Heating, piercing, hot rolling and sizing to obtain a hot rolled pipe: heating the tube blank at 1180-1300 ℃ for 2-6 hours, then performing high-temperature perforation, hot rolling, sizing and other high-temperature deformation at 950-1250 ℃, and processing the tube blank into a hot rolled tube with phi 52-76 mm multiplied by 4.5-8.5 mm.
(3) Intermediate heat treatment: controlling the hot rolled pipe to anneal in the temperature range of 680-900 ℃, and preserving the heat for 0.25-3 h.
(4) Cold drawing or cold rolling.
(5) Normalizing or annealing heat treatment: controlling the normalizing or annealing temperature to be 700-880 ℃, keeping the temperature for 0.5-3 h, and then air-cooling or air-cooling. The diameter phi of the finally manufactured finished seamless steel tube is between 30 and 55mm, and the wall thickness is 3.0 to 5.5 mm.
It should be noted that, in the present invention, the chemical composition design and related processes of the high strength seamless steel pipes with good fatigue resistance of examples 1-15 satisfy the design specification requirements of the present invention. The comparative seamless steel pipes of comparative examples 1 to 5, however, had parameters in the chemical composition design that did not meet the design specification requirements of the present invention.
Table 1 shows the mass percentages of the chemical elements of the high-strength seamless steel pipes with good fatigue resistance of examples 1 to 15 and the comparative seamless steel pipes of comparative examples 1 to 5.
Table 1 (wt.%, balance Fe and unavoidable impurities other than P, S and O)
Table 2 lists the specific process parameters in the above process steps for the high strength seamless steel pipes with good fatigue resistance of examples 1-15 and the comparative seamless steel pipes of comparative examples 1-5.
Table 2.
The obtained high-strength seamless steel pipes with good fatigue resistance of examples 1 to 15 and the comparative seamless steel pipes of comparative examples 1 to 5 were sampled respectively, and the normal temperature mechanical property test and the cold working property test were performed on the finished plates of each example and comparative example, respectively. The results of the mechanical property test and the cold workability test of each example and comparative example are shown in table 3, respectively.
The relevant performance test means are as follows:
and (3) testing mechanical properties: part 1 of the tensile test of metallic materials according to GB/T228.1-2010: the room temperature tensile test method is used for detecting the mechanical properties of the seamless steel pipes of the examples and the comparative examples.
And (3) cold processing performance detection: the seamless steel pipes of the examples and the comparative examples were subjected to a swaging process, and a cold rotary swaging process apparatus for a practical driveshaft tube was used. After the completion of the swaging process, it was necessary to examine whether or not cracks were generated in the seamless steel pipes of each example and comparative example during the swaging process.
Table 3 shows the results of the room temperature mechanical property test of the high strength seamless steel pipes excellent in fatigue resistance of examples 1 to 15 and the comparative seamless steel pipes of comparative examples 1 to 5.
Table 3.
In table 3, "o" indicates: the seamless steel pipes of the examples or comparative examples did not develop cracks in the swaging process; "×" indicates that cracks were generated in the die forging process in this example or comparative example.
After the mechanical property detection and the cold processing property detection of the seamless steel pipes in each embodiment and the comparative example are finished, quenching and tempering heat treatment needs to be carried out on the high-strength seamless steel pipes with good fatigue resistance of the finished products in the embodiments 1-15 and the comparative seamless steel pipes in the comparative examples 1-5, wherein the quenching temperature is 880-920 ℃, the heat preservation time is 0.5-2 min, and then water cooling is carried out; tempering temperature is 150-300 ℃, the heat preservation time is 20-40 min, and then air cooling is carried out. The specific quenching and tempering heat treatment process parameters used for the seamless steel pipes of each example and comparative example are shown in table 4. Table 4 shows the specific process parameters of quenching and temper rolling heat treatment of the high strength seamless steel pipes with good fatigue resistance of examples 1 to 15 and the comparative seamless steel pipes of comparative examples 1 to 5.
Table 4.
After the quenching and tempering heat treatment, the high-strength seamless steel pipes of examples 1 to 15 and the comparative seamless steel pipes of comparative examples 1 to 5 after the quenching and tempering heat treatment were sampled again, the normal temperature mechanical properties and the torsional fatigue properties after quenching and tempering were examined, and the test results of the quenching and tempering heat treatment of each example and comparative example are listed in table 5.
The method for detecting the normal-temperature mechanical properties of the seamless steel pipes of the examples and the comparative examples after quenching and tempering heat treatment is the same as the mechanical property detection means adopted before quenching and tempering heat treatment.
The relevant torsion fatigue performance test means is as follows:
and (3) torsion fatigue performance testing: the fatigue life of parts of the seamless steel pipes of each example and each comparative example was tested under a high load condition with an input torque of 2000n.m, a medium load condition with an input torque of 1200n.m, and a low load condition with an input torque of 800n.m, using a torsional fatigue testing machine dedicated for a propeller shaft, and the torsional fatigue properties were measured respectively.
Table 5 shows the test results of the high strength seamless steel pipes excellent in fatigue resistance of examples 1 to 15 and the comparative seamless steel pipes of comparative examples 1 to 5 after the quenching and tempering heat treatment.
Table 5.
It can be seen from a combination of tables 3 and 5 that the high strength seamless steel pipes of examples 1 to 15 are significantly superior in all of the comprehensive mechanical properties to the comparative seamless steel pipes of comparative examples 1 to 3 before the quenching and tempering heat treatment. After quenching and tempering heat treatment, the comprehensive mechanical properties of the high-strength seamless steel pipes in the examples 1 to 15 are obviously superior to those of the comparative seamless steel pipes in the comparative examples 4 to 5, and the torsional fatigue properties of the high-strength seamless steel pipes are superior to those of the comparative examples 2 and 5.
As can be seen from Table 3, the high-strength seamless steel pipes with good fatigue resistance of examples 1 to 15 of the present invention have very excellent room temperature mechanical properties and cold workability before the quenching and tempering heat treatment, and the yield strength Rp0.2 thereof is between 312MPa and 448MPa, the tensile strength Rm thereof is between 484 MPa and 648MPa, and the elongation A thereof is 50 Between 22% and 31%.
Accordingly, it can be seen from Table 5 that the high strength seamless steel pipes of examples 1 to 15 according to the present invention, which have good fatigue resistance, still have very excellent room temperature mechanical properties after the quenching and tempering heat treatment, and in addition, have good torsional fatigue life. The performance of the high-strength seamless steel pipes produced in the embodiments 1 to 15 by the invention after quenching and tempering heat treatment meets the following requirements: the yield strength Rp0.2 is 1213MPa to 1493MPa, the tensile strength Rm is 1703MPa to 1892MPa, and the elongation A 50 Between 8% and 15%, the fatigue life under high input torque (input torque 2000N.m) is 3289-5148 times, and the fatigue under medium input torque (input torque 1200N.m)The fatigue life is 32908-59891 times, and the fatigue life under low input torque (input torque 800N.m) is 1062203-1574338 times.
In conclusion, the high-strength seamless steel pipe with good fatigue resistance has excellent performance, does not crack in the cold machining process, does not crack in the quenching and tempering process, is particularly suitable for parts such as automobile driving shafts and the like which bear high-strength torsional loads, and has wide application prospect.
FIG. 1 schematically shows hardenability test curves measured by holding high-strength seamless steel pipes of examples 7 and 8 at 900 ℃ for 40 min.
As shown in FIG. 1, FIG. 1 schematically shows the change curves of hardness with distance of the high-strength seamless steel pipes of examples 7 and 8, and it can be seen from the change curves that the hardness after hardening and tempering can reach 55HRC or more within the range of the specification and the wall thickness of the product of the present invention.
FIG. 2 is a microstructure morphology photograph of the high strength seamless steel tube of example 9 at one viewing angle.
FIG. 3 is a microstructure morphology photograph of the high strength seamless steel tube of example 9 at another viewing angle.
As can be seen from FIGS. 2 and 3, in this embodiment, the microstructure of the high-strength seamless steel pipe of example 9 was ferrite + sorbite, and the depth of the semi-decarburization conducted inward from the outer wall surface in the wall thickness direction was 120 μm or less.
It should be noted that 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 contradicted by 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 (15)
1. A high-strength seamless steel pipe having excellent fatigue resistance, characterized by comprising, in addition to Fe and unavoidable impurities, the following chemical elements in mass percent:
C：0.28～0.38％，Si≤0.35％，Mn：0.5～1.0％，Cr：0.6～1.6％，Mo：0.1～0.35％，N：0.0035～0.0085％,Al：0.020～0.055％,Ca：0.0005～0.005％。
2. the high-strength seamless steel pipe with good fatigue resistance as claimed in claim 1, wherein the high-strength seamless steel pipe comprises the following chemical elements in percentage by mass:
c: 0.28-0.38%, Si more than 0 and less than or equal to 0.35%, Mn: 0.5-1.0%, Cr: 0.6-1.6%, Mo: 0.1-0.35%, N: 0.0035-0.0085%, Al: 0.020-0.055%, Ca: 0.0005 to 0.005%; the balance being Fe and unavoidable impurities.
3. The high-strength seamless steel pipe excellent in fatigue resistance as recited in claim 1 or 2, wherein the chemical elements satisfy at least one of the following in percentage by mass:
C：0.31～0.36％，
Si≤0.25％，
Mn：0.55～0.95％，
Cr：0.80～1.20％，
Mo：0.15～0.30％，
N：0.0045～0.0065％,
Al：0.025～0.045％,
Ca：0.001～0.004％。
4. the high-strength seamless steel pipe excellent in fatigue resistance as claimed in claim 1 or 2, wherein P is 0.015% or less, S is 0.008% or less, and O is 0.0035% or less among the inevitable impurities.
5. The high-strength seamless steel pipe excellent in fatigue resistance as recited in claim 1 or 2, wherein the microstructure thereof is ferrite + sorbite.
6. The high-strength seamless steel pipe excellent in fatigue resistance as recited in claim 1 or 2, wherein the depth of the semi-decarburization inward from the outer wall surface in the wall thickness direction is 120 μm or less.
7. The high-strength seamless steel pipe excellent in fatigue resistance as claimed in claim 1 or 2, wherein the diameter thereof is 30 to 55mm and/or the wall thickness thereof is 3.0 to 5.5 mm.
8. The high-strength seamless steel pipe excellent in fatigue resistance as claimed in claim 1 or 2, which satisfies the following properties before the heat treatment for quenching and tempering: the yield strength Rp0.2 is 300-450MPa, and the tensile strength is
Rm is more than or equal to 450MPa, and elongation rate A 50 ≥22％。
9. The high-strength seamless steel pipe excellent in fatigue resistance as recited in claim 1 or 2, wherein the properties after the quenching and tempering heat treatment satisfy at least one of: the yield strength Rp0.2 is more than or equal to 1200MPa, the tensile strength Rm is more than or equal to 1700MPa, and the elongation percentage A 50 Not less than 8%, the fatigue life under high input torque is not less than 3000 times, the fatigue life under medium input torque is not less than 30000 times, and the fatigue life under low input torque is not less than 1000000 times.
10. The method of producing a high-strength seamless steel pipe excellent in fatigue resistance as recited in any one of claims 1 to 9, comprising the steps of:
(1) preparing a tube blank;
(2) heating, perforating, hot rolling and sizing to obtain a hot-rolled pipe;
(3) intermediate heat treatment;
(4) cold drawing or cold rolling;
(5) normalizing or annealing heat treatment.
11. The method of claim 10, wherein the heating temperature in step (2) is 1180 to 1300 ℃ and then the temperature is maintained for 2 to 6 hours.
12. The method of claim 10, wherein in the step (2), the piercing temperature is 950 to 1250 ℃.
13. The method of claim 10, wherein in step (3), the annealing is performed at a temperature of 680 to 900 ℃ and the temperature is maintained for 0.25 to 3 hours.
14. The method according to claim 10, wherein in the step (5), the normalizing or annealing temperature is 700 to 880 ℃ and the holding time is 0.5 to 3 hours.
15. The manufacturing method according to any one of claims 10 to 14, further comprising the steps of (6) quenching and tempering heat treatment, wherein the quenching temperature is 880 to 920 ℃, the holding time is 0.5 to 2min, and then water cooling; tempering at 150-300 ℃, keeping the temperature for 20-40 min, and then air cooling.
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| CN116815048A (en) * | 2023-03-31 | 2023-09-29 | 本钢板材股份有限公司 | Alloy structural steel for railway axle and preparation method thereof |
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| JPH11302785A (en) * | 1998-04-20 | 1999-11-02 | Sumitomo Metal Ind Ltd | Steel for seamless steel pipe |
| CN105154765A (en) * | 2015-09-24 | 2015-12-16 | 宝山钢铁股份有限公司 | Seamless steel tube with high strength and toughness and manufacturing method thereof |
| CN106133176A (en) * | 2014-04-03 | 2016-11-16 | 杰富意钢铁株式会社 | Pipe as fuel injection seamless steel pipe |
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| JPH11302785A (en) * | 1998-04-20 | 1999-11-02 | Sumitomo Metal Ind Ltd | Steel for seamless steel pipe |
| CN106133176A (en) * | 2014-04-03 | 2016-11-16 | 杰富意钢铁株式会社 | Pipe as fuel injection seamless steel pipe |
| CN105154765A (en) * | 2015-09-24 | 2015-12-16 | 宝山钢铁股份有限公司 | Seamless steel tube with high strength and toughness and manufacturing method thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN116815048A (en) * | 2023-03-31 | 2023-09-29 | 本钢板材股份有限公司 | Alloy structural steel for railway axle and preparation method thereof |
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