CN117305684A - High-strength and high-toughness seamless steel tube for motor shaft with good processability and manufacturing method thereof - Google Patents

High-strength and high-toughness seamless steel tube for motor shaft with good processability and manufacturing method thereof Download PDF

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Publication number
CN117305684A
CN117305684A CN202210711762.7A CN202210711762A CN117305684A CN 117305684 A CN117305684 A CN 117305684A CN 202210711762 A CN202210711762 A CN 202210711762A CN 117305684 A CN117305684 A CN 117305684A
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China
Prior art keywords
strength
seamless steel
percent
less
motor shaft
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Inventor
骆素珍
翟国丽
高展
刘文灏
孙文
陈志宏
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Baoshan Iron and Steel Co Ltd
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Baoshan Iron and Steel Co Ltd
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Priority to CN202210711762.7A priority Critical patent/CN117305684A/en
Priority to PCT/CN2023/101467 priority patent/WO2023246799A1/en
Publication of CN117305684A publication Critical patent/CN117305684A/en
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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
    • 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
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/26—Methods of annealing
    • 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
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/26—Methods of annealing
    • C21D1/28—Normalising
    • 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
    • C21D11/00—Process control or regulation for heat treatments
    • 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
    • C21D6/00—Heat treatment of ferrous alloys
    • 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
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/005—Heat treatment of ferrous alloys containing Mn
    • 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
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/008—Heat treatment of ferrous alloys containing Si
    • 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
    • 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
    • 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
    • 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
    • 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
    • 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
    • C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
    • 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
    • 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
    • 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
    • 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
    • C22C38/14—Ferrous alloys, e.g. steel alloys containing titanium or zirconium
    • 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
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/58—Ferrous alloys, e.g. steel alloys containing chromium with nickel with more than 1.5% by weight of manganese
    • 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
    • C21D2211/001—Austenite
    • 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
    • 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
    • C21D2211/008—Martensite
    • 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

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Manufacturing & Machinery (AREA)
  • Heat Treatment Of Articles (AREA)

Abstract

The invention discloses a high-strength and high-toughness seamless steel tube for a motor shaft, which has good processability, contains Fe and unavoidable impurity elements, and also contains the following chemical elements in percentage by mass: c: 0.40-0.60%, si is more than 0 and less than or equal to 0.25%, mn:0.5 to 1.2 percent, ti is less than or equal to 0.045 percent, B is less than or equal to 0.0045 percent, N: 0.0040-0.009%, al:0.015 to 0.045 percent, ca+Mg:0.001 to 0.006 percent. Correspondingly, the invention also discloses a manufacturing method of the high-strength and high-toughness seamless steel tube for the motor shaft, which comprises the following steps: (1) preparing a tube blank; (2) heating, perforating, hot rolling and reducing; (3) intermediate heat treatment: annealing the hot rolled pipe material at the temperature of 650-800 ℃ for 20-80 min; (4) cold drawing; (5) heat treatment of finished products: normalizing at 750-820 deg.c for 20-60 min to obtain ferrite-pearlite structure.

Description

High-strength and high-toughness seamless steel tube for motor shaft with good processability and manufacturing method thereof
Technical Field
The present invention relates to a steel pipe and a method for manufacturing the same, and more particularly, to a seamless steel pipe and a method for manufacturing the same.
Background
In recent years, in a large background of carbon and pollution reduction, the sales volume of electric vehicles has come to be rapidly increased, and the market and the requirements for lightening the electric vehicles themselves have become more and more stringent. In order to achieve the maximum light weight, in addition to the main body adopting high-strength steel and light materials, parts which occupy smaller weight in the whole vehicle, such as a motor shaft and other vehicle structural parts, are gradually brought into a weight reduction row, and the industry has been in the trend of replacing solid bars and forging materials by hollow pipes.
In the prior art, components such as a motor shaft of an electric vehicle and the like have a function of transmitting motor torque to a driving wheel, and are very important safety components. Due to the high-speed operation of the motor shaft, the motor shaft is subjected to not only a great torsional moment but also traction force, braking force and the like from wheels in actual use, for example: longitudinal force, lateral force, vertical force, and shock impact force. Therefore, in the face of such severe use requirements, in the actual manufacture of motor shafts, materials with high strength and plasticity are generally required in the industry to ensure that sufficient torsion resistance and fatigue resistance are obtained.
In addition, because of the different types of vehicles, different motor shafts can obtain the required torsion resistance and fatigue resistance under the high-speed rotation condition through the processing procedures of integral cold extrusion, cutting processing and the like. Therefore, when designing such a steel for motor shafts, it is necessary to combine good cold workability while taking into consideration high strength and toughness and high fatigue properties.
For example: chinese patent document with publication number CN104962838A and publication date 2015, 10 month 07, entitled "high-strength steel, high-strength plastic seamless steel pipe for automotive transmission half shaft and manufacturing method thereof" discloses a high-strength steel, high-strength plastic seamless steel pipe for automotive transmission half shaft and manufacturing method thereof, the chemical components of which are: c:0.07 to 0.15 percent, si:0.1 to 1.0 percent, mn:2.0 to 2.6 percent, ni:0.05 to 0.6 percent, cr:0.2 to 1.0 percent, mo:0.1 to 0.6 percent, B:0.001-0.006%, cu:0.05 to 0.50 percent; 0.015 to 0.060 percent of Al; nb 0.02-0.1%; v is 0.02-0.15%. In the technical scheme, the steel pipe adopts a low-C design, and the prepared finished product has low strength, is favorable for welding and is more suitable for the automobile half shaft produced by friction stir welding.
Also for example: chinese patent document publication No. CN1388834a, publication No. 1 month and 1 day 2003, entitled "a high carbon steel pipe excellent in cold workability and high frequency hardening properties and a method for producing the same", discloses a high carbon steel pipe excellent in cold workability and high frequency hardening properties and a method for producing the same, comprising the following chemical components by mass percent: c0.30-0.80%, si less than or equal to 2%, mn less than or equal to 3%. In the technical scheme, a special rolling technology is utilized to obtain a structure with cementite less than 1um, so that the cold processing performance and the high-frequency hardening performance of the steel are improved.
Unlike the above prior art, in order to solve the problems existing in the prior art, the present invention is expected to develop and obtain a new high-strength seamless steel pipe and a manufacturing method thereof for manufacturing a motor shaft.
Disclosure of Invention
The invention aims to provide a high-strength and high-toughness seamless steel pipe for a motor shaft, which has good processing performance, can obtain excellent mechanical properties through reasonable component matching and process design, has excellent mechanical properties before and after tempering heat treatment, has hardness of more than 58HRC after the tempering heat treatment, has a strength-plastic product (the product of tensile strength and elongation) of more than 15000MPa, can resist torque of more than 300KN, is particularly suitable for preparing motor shaft parts bearing high torsional load, and has good popularization prospect and application value.
In order to achieve the above object, the present invention provides a high-strength and high-toughness seamless steel pipe for motor shafts, which has good workability, contains Fe and unavoidable impurity elements, and further contains the following chemical elements in mass percent:
C：0.40～0.60％，0＜Si≤0.25％，Mn：0.5～1.2％，Ti≤0.045％，B≤0.0045％，N：0.0040～0.009％，Al：0.015～0.045％,Ca+Mg：0.001～0.006％。
further, in the high-strength and high-toughness seamless steel tube for the motor shaft, the mass percentages of the chemical elements are as follows:
c: 0.40-0.60%, si is more than 0 and less than or equal to 0.25%, mn:0.5 to 1.2 percent, ti is less than or equal to 0.045 percent, B is less than or equal to 0.0045 percent, N: 0.0040-0.009%, al:0.015 to 0.045 percent, ca+Mg:0.001 to 0.006 percent; the balance being Fe and unavoidable impurities.
In the high-strength and high-toughness seamless steel tube for the motor shaft, the design principle of each chemical element is as follows:
c: in the high-strength and high-toughness seamless steel tube for the motor shaft, the improvement of the content of the element C is beneficial to improving the strength and fatigue resistance of the material, but the content of the element C in the steel tube is not too high, and when the content of the element C is too high, the toughness and plasticity of the material are reduced, cold working is not facilitated, and the quality problems of processing cracks, serious decarburization and the like are easy to occur. Therefore, in the high-strength and high-toughness seamless steel tube for the motor shaft, the mass percent of the C element is controlled to be between 0.40 and 0.60 percent in order to ensure the quenching hardness and the hardenability of the material, so that the hardenability of the material is ensured, the quenching crack sensitivity is reduced, and the cold processing performance of the steel can be ensured.
Of course, in some preferred embodiments, in order to obtain a better implementation effect, the mass percentage of the element C may be further preferably controlled between 0.45 and 0.55%.
Si: in the high-strength and high-toughness seamless steel tube for the motor shaft, the influence of Si element on cold workability is large, and the lower the Si element content in the steel tube is, the better the cold workability of the steel tube is. In general, si is a residual element of steel after smelting and deoxidizing, and if a lower content of Si is required in the steel, a deoiling mode in the molten steel smelting process needs to be changed, so that the deoxidizing level needs to be ensured by comprehensively controlling the content of Al and Ca, and no adverse effect of corresponding nonmetallic inclusion on the fatigue resistance of the steel is ensured. Based on the above, in the high-strength and high-toughness seamless steel tube for the motor shaft, the mass percentage of Si element is controlled to be more than 0 and less than or equal to 0.25 percent.
Of course, in some preferred embodiments, in order to obtain a more preferable implementation effect, the mass percentage of Si element may be further preferably controlled to be 0 < Si.ltoreq.0.20%.
Mn: in the high-strength and high-toughness seamless steel tube for the motor shaft, the content of Mn element is improved, the strength of the material can be improved, mn can stabilize P, S element, the formation of low-melting-point sulfide is avoided, and the hot processing performance of the material is improved. In order to achieve the above effects, the Mn element content in the steel is not too low, and when the Mn element content in the steel is too low, the P, S element cannot be well stabilized, and the desired effect cannot be achieved; meanwhile, the content of Mn element in the steel is not too high, and when the content of Mn element in the steel is too high, cold working deformation hardening is serious, and die abrasion is aggravated. Therefore, considering the influence of Mn element content on the performance of steel, in the high-strength and high-toughness seamless steel tube for the motor shaft, the mass percent of Mn element is controlled to be between 0.5 and 1.2 percent.
Of course, in some preferred embodiments, in order to obtain a more preferable implementation effect, the mass percentage of Mn element may be further preferably controlled to be between 0.6 and 1.0%.
Ti: in the high-strength and high-toughness seamless steel tube for the motor shaft, the hardenability of the steel can be improved by a proper amount of Ti element, and the Ti element can play a role of refining grains together with C and N elements, but the content of the Ti element in the steel is not too high, and the smelting continuous casting is difficult due to the too high content of Ti. Therefore, in the high-strength and high-toughness seamless steel tube for the motor shaft, the mass percentage of Ti element is controlled to be less than or equal to 0.045 percent.
Of course, in some preferred embodiments, in order to obtain a more preferable implementation effect, the content of Ti element may be further preferably controlled to be between 0.02 and 0.04% by mass.
B: in the high-strength and high-toughness seamless steel tube for the motor shaft, the appropriate amount of B content can improve the hardenability and plasticity of the steel, but the B element with too high content can cause high-temperature brittleness of the steel. Therefore, in the high-strength and high-toughness seamless steel tube for the motor shaft, the mass percentage of the B element is controlled to be less than or equal to 0.0045 percent.
Of course, in some preferred embodiments, in order to obtain a more preferable implementation effect, the mass percentage of the B element may be further preferably controlled to be between 0.002 and 0.004%.
N: in the high-strength and high-toughness seamless steel tube for the motor shaft, N is controlled in a proper range, so that the N can refine grains together with Ti and B elements, and the performance of a material is improved. Therefore, in the high-strength and high-toughness seamless steel tube for the motor shaft, the mass percentage of N element is controlled to be between 0.0040 and 0.009 percent.
Of course, in some preferred embodiments, in order to obtain a more preferable implementation effect, the mass percentage of the N element may be further preferably controlled to be between 0.0045 and 0.0085%.
Al: in the high-strength and high-toughness seamless steel tube for the motor shaft, al is a deoxidizer in the smelting process, and can ensure the deoxidizing effect of steel types together with elements such as Si and the like, and ensure the purity of the steel, thereby ensuring the fatigue resistance of the material. However, it should be noted that the content of Al element in the steel is not too high, and when the content of Al element in the steel is too high, abnormal alumina inclusion may be caused. Therefore, in order to exert the beneficial effects of the Al element, the high-strength and high-toughness seamless steel tube for the motor shaft controls the mass percentage of the Al element to be between 0.015 and 0.045 percent.
Of course, in some preferred embodiments, in order to obtain a better implementation effect, the mass percentage of the N element may be further preferably controlled to be between 0.015 and 0.035%.
Ca. Mg: in the high-strength and high-toughness seamless steel tube for the motor shaft, the shape and the performance of nonmetallic inclusion can be improved by proper amounts of Ca and Mg, so that the fatigue performance and the like of materials are improved. Therefore, in the seamless steel tube for a high-strength and high-toughness free-cutting motor shaft according to the present invention, in order to exert the beneficial effects of the Ca and Mg elements, the inventors can consider that the addition of Ca and/or Mg elements to the steel requires that the sum of the mass percentages of Ca and Mg elements "ca+mg" be controlled to be 0.001 to 0.006%.
Of course, in some preferred embodiments, in order to obtain a better implementation effect, the sum of the mass percentages of the Ca and Mg elements, "ca+mg", may be further preferably controlled to be between 0.001 and 0.004%.
Further, in the high-strength and high-toughness seamless steel tube for the motor shaft, among unavoidable impurities, P is less than or equal to 0.020%, S is less than or equal to 0.008%, and O is less than or equal to 0.0030%.
Further, in the high-strength and high-toughness seamless steel tube for the motor shaft, among unavoidable impurities, P is less than or equal to 0.015%, S is less than or equal to 0.005%, and O is less than or equal to 0.0025%.
In the high-strength and high-toughness seamless steel pipe for the motor shaft, the P element and the S element are all impurity elements in the steel pipe, and the content of the impurity elements in the high-strength and high-toughness seamless steel pipe for the motor shaft is reduced as far as possible in order to obtain the pipe with better performance and better quality under the condition of technical conditions.
In the invention, P, S is iron and steel raw materials or impurity elements introduced in the production process, and P element can embrittle grain boundaries and deteriorate the toughness and the processing performance of the material; the S element can be matched to form sulfide with low melting point, so that the processing performance and the mechanical property of the steel are reduced.
Therefore, in the present invention, it is necessary to strictly control the content of P, S, O element in steel to P.ltoreq.0.020%, S.ltoreq.0.008%, O.ltoreq.0.0030%. Of course, in some preferred embodiments, in order to obtain a better implementation effect, the content of the P, S, O element may be further controlled to satisfy: p is less than or equal to 0.015 percent, S is less than or equal to 0.005 percent, and O is less than or equal to 0.0025 percent.
Further, in the high-strength and high-toughness seamless steel tube for the motor shaft, the mass percentage of each chemical element further satisfies at least one of the following:
C：0.45～0.55％，
0＜Si≤0.20％，
Mn：0.6～1.0％，
Ti：0.02～0.04％，
B：0.002～0.004％，
N：0.0045～0.0085％,
Al：0.015～0.035％,
Ca+Mg：0.001～0.004％。
further, in the high-strength and high-toughness seamless steel tube for the motor shaft, the microstructure is ferrite and pearlite.
Further, in the high-strength and high-toughness seamless steel tube for the motor shaft, the microstructure subjected to tempering heat treatment is martensite and retained austenite with the volume phase ratio of 1-25%.
Further, in the high-strength and high-toughness seamless steel tube for the motor shaft, the yield strength Rp of the seamless steel tube 0.2 Not less than 400MPa, tensile strength R m 550MPa or more, elongation A 50 ≥22％。
Further, in the high-strength and high-toughness seamless steel tube for the motor shaft, the performance of the high-strength and high-toughness seamless steel tube for the motor shaft after quenching and tempering heat treatment meets the following conditions: yield strength R p0.2 Not less than 1000MPa, tensile strength R m Not less than 1400MPa, elongation A 50 More than or equal to 5 percent, the hardness is more than or equal to 58HRC, and the product of strength and plastic is strongMore than 15000MPa, and the torsion resistance is more than or equal to 300KN.
Accordingly, another object of the present invention is to provide a method for manufacturing the high-strength and high-toughness seamless steel tube for a motor shaft, which is optimized in process, simple and convenient in manufacturing process and easy to implement, and can effectively prepare the high-strength and high-toughness seamless steel tube for a motor shaft, and has a very good application prospect.
In order to achieve the above object, the present invention provides a method for manufacturing the high strength and toughness seamless steel pipe for a motor shaft, comprising the steps of:
(1) Preparing a tube blank;
(2) Heating, perforating, hot rolling and reducing;
(3) Intermediate heat treatment: annealing the hot rolled pipe material at the temperature of 650-800 ℃ for 20-80 min;
(4) Cold drawing;
(5) And (3) heat treatment of a finished product: normalizing at 750-820 deg.c for 20-60 min to obtain ferrite-pearlite structure.
In the technical scheme of the invention, in the tube blank manufacturing process of the step (1), operators can smelt and refine the tube blank by using an electric furnace or a converter to pour the tube blank, and cut the tube blank to obtain the tube blank with the required size by using continuous casting. In order to meet the requirements of an automobile motor shaft on the dimensional precision of a steel pipe and the surface state in the cold working process, the hot rolled pipe material obtained in the step (1) is subjected to further intermediate heat treatment, cold drawn to the required specification and dimensional precision, and then further finished product heat treatment is performed, so that the finished product raw material with good cold-cold working performance is finally obtained.
In the step (3), during the intermediate heat treatment process, the hot rolled tube stock is controlled to be annealed at a temperature of 650-800 ℃ and kept for 20-80 min, so that the cold drawing process in the subsequent step (4) can be ensured to be smoothly carried out.
In addition, in the heat treatment of the finished product in the step (5), the cold drawn pipe material prepared in the step (4) is required to be normalized at the temperature of 750-820 ℃, the heat preservation is carried out for 20-60 min, the atmosphere in the furnace is controlled, no full decarburization (namely no full ferrite tissue area is arranged on the surface of the steel pipe) is ensured, and the half decarburization depth is less than or equal to 150 mu m. In the technical scheme, the normalizing temperature and the cooling mode are controlled to be matched, so that the steel pipe can be ensured to obtain a ferrite and pearlite structure, and the normalized pipe with strength and toughness meeting the cold working requirements is obtained.
Further, in the production method of the present invention, in the step (2), the tube blank is heated and held at 1210 to 1280 ℃ for 30 to 150 minutes.
Further, in the manufacturing method according to the present invention, in the step (2), the perforation temperature is controlled to 1150 to 1250 ℃.
Further, in the manufacturing method of the present invention, in the step (2), the hot continuous rolling temperature is controlled to be 1000 to 1200 ℃.
Further, in the production method of the present invention, in the step (2), the temperature of the sheet is controlled to 950 to 1000 ℃.
Compared with the prior art, the high-strength and high-toughness seamless steel tube for the motor shaft and the manufacturing method thereof have the following advantages and beneficial effects:
in the invention, the inventor can obtain a brand new high-strength and high-toughness seamless steel tube for the motor shaft through reasonable component matching and process design, wherein the microstructure of the high-strength and high-toughness seamless steel tube for the motor shaft is ferrite and pearlite after finished product heat treatment, and the microstructure of the high-strength and high-toughness seamless steel tube for the motor shaft is martensite and residual austenite with the volume phase ratio of 1-25% after further heat treatment.
Rp of the high-strength and high-toughness seamless steel tube for motor shafts, prepared by the invention, in finished product state 0.2 Not less than 400MPa, tensile strength R m 550MPa or more, elongation A 50 More than or equal to 22 percent; however, after the high-strength and high-toughness seamless steel tube for the motor shaft is subjected to further quenching and tempering heat treatment, the strength of the high-strength and high-toughness seamless steel tube for the motor shaft can be obviously improved, and the yield strength Rp of the high-strength and high-toughness seamless steel tube for the motor shaft is obviously improved 0.2 Not less than 1000MPa, tensile strength R m Not less than 1400MPa, elongation A 50 More than or equal to 5 percent, the hardness after the heat treatment is modulated to be more than 58HRC, the product of the strength and the plastic product (the product of the tensile strength and the elongation) is more than 15000MPa, the torque of more than 300KN can be resisted, and the heat treatment device is particularly suitable forThe method has good popularization prospect and application value in preparing motor shaft parts bearing high torsional load.
Detailed Description
The high-strength and high-toughness seamless steel tube for motor shafts and the manufacturing method thereof according to the present invention will be further explained and illustrated with reference to specific examples, but the explanation and illustration do not unduly limit the technical scheme of the present invention.
Examples 1 to 10 and comparative examples 1 to 2
The high-strength and high-toughness seamless steel pipes for motor shafts of the examples 1-10 and the comparative steel pipes of the comparative examples 1-2 are prepared by the following steps:
(1) Smelting and refining by an electric furnace or a converter according to the mass percentages of chemical elements shown in the table 1 to obtain a tube blank, and continuously casting and cutting the tube blank to obtain the tube blank with the required size.
(2) Heating, perforating, hot rolling and reducing: heating and preserving the heat of the tube blank at 1210-1280 ℃ for 30-150 min, carrying out high temperature Wen Chuankong at 1150-1250 ℃, then carrying out high temperature hot continuous rolling at 1000-1200 ℃, further carrying out stretch reduction after finishing hot rolling, and controlling the stretch reduction temperature to 950-1000 ℃ so as to manufacture the hot rolled tube material.
(3) Intermediate heat treatment: annealing the hot rolled pipe material at 650-800 deg.c for 20-80 min.
(4) And (5) cold drawing.
(5) And (3) heat treatment of a finished product: normalizing the cold drawn pipe material at the temperature of 750-820 ℃ for 20-60 min to obtain ferrite and pearlite structure.
It should be noted that the chemical element components and the related process design of the high-strength and high-toughness seamless steel tube for motor shafts in the embodiments 1-10 of the present invention all meet the requirements of the design specification of the present invention. The comparative steel pipes of comparative examples 1-2 were also prepared by the above-described process steps, but the chemical element compositions and/or the related process parameters thereof had parameters which did not meet the design of the present invention.
Table 1 shows the mass percentages of each chemical element in the high-strength seamless steel pipe for motor shafts of examples 1 to 10 and the comparative steel pipe of comparative examples 1 to 2.
Table 1 (balance Fe and unavoidable impurities other than P, S, O)
Table 2 shows the specific process parameters employed in the above manufacturing process steps for the high strength and toughness seamless steel pipes for motor shafts of examples 1-10 and the comparative steel pipes of comparative examples 1-2.
Table 2.
The prepared motor shafts of the finished products of examples 1 to 10 were sampled with high-strength seamless steel pipes and comparative steel pipes of comparative examples 1 to 2, respectively, and the microstructure of each of the steel pipes of examples and comparative examples before heat treatment without tempering was observed, and each of the properties of each of examples and comparative examples was tested to obtain normal temperature mechanical properties before tempering, and the test results of the relevant mechanical properties are shown in table 3.
The correlation performance detection means are as follows:
tensile test: according to section 1 according to the tensile test according to the metal material of GB/T228.1-2010: room temperature tensile test method to test yield strength, tensile strength and elongation values at room temperature of the steel pipes of each example and comparative example obtained before the tempering heat treatment.
Table 3 shows the results of performance tests of the high-strength seamless steel pipes for motor shafts of examples 1 to 10 and the comparative steel pipes of comparative examples 1 to 2, which were not subjected to the tempering heat treatment.
Table 3.
As can be seen from the above Table 3, the high strength and toughness seamless steel pipes for motor shafts of examples 1 to 10 already have excellent mechanical properties and yield strength R p0.2 Between 417 and 506MPa, its tensile strength R m Between 564 and 672MPa, the elongation A 50 Between 23-30%. In addition, it was found that the microstructure of the high strength and toughness seamless steel pipes for motor shafts of examples 1 to 10 was ferrite+pearlite before the quenching and tempering heat treatment.
Accordingly, in order to further illustrate that the high-strength and high-toughness seamless steel pipe for a motor shaft according to the present invention still has very excellent properties after being subjected to tempering heat treatment, the inventors further sample the prepared high-strength and high-toughness seamless steel pipes for motor shafts of finished product examples 1 to 10 and comparative steel pipes of comparative examples 1 to 2, respectively, and perform tempering heat treatment on the steel pipes of each example and comparative example, and control the tempering heat treatment process to be: wherein the quenching temperature is 820-880 ℃, the heat preservation time is 15-30 min, and the water cooling is carried out; tempering temperature is 150-300 ℃, heat preservation time is 20-40 min, and air cooling is performed.
After finishing the tempering heat treatment for the sample steel pipes of examples and comparative examples, the inventors further conducted mechanical property tests on the steel pipes after the tempering heat treatment to measure the properties of the steel pipes after the tempering heat treatment, and the results of the related mechanical property tests are shown in table 4 below.
When the mechanical properties of the steel pipes of examples 1 to 10 and comparative examples 1 to 2 after the heat treatment were tested, the tensile test procedure was carried out in the same manner as the test procedure of Table 3, and the yield strength, tensile strength and elongation of the steel pipes of examples 1 to 10 and comparative examples 1 to 2 after the heat treatment were measured.
In addition to the above properties, further tests were carried out on the other properties of the steel pipes of each example and comparative example after the conditioning heat treatment, and the relevant test means were as follows:
hardness test: rockwell hardness tester was used to measure Hardness (HRC) of the steel pipes of examples 1 to 10 and comparative examples 1 to 2 after the tempering heat treatment.
Anti-torsion performance test: a static torsion test apparatus was used to measure the torsion resistance of the steel pipes of examples 1 to 10 and comparative examples 1 to 2 after the heat treatment.
Table 4 shows the results of performance tests of the high-strength seamless steel pipes for motor shafts of examples 1 to 10 and the comparative steel pipes of comparative examples 1 to 2 after heat-treatment by tempering.
Table 4.
Note that: in table 4 above, rm×a50 is the hard product, which is the product of tensile strength and elongation.
As can be seen from Table 4, the high strength and toughness seamless steel pipes for motor shafts according to examples 1 to 10 of the present invention are significantly superior in combination properties to the comparative steel pipes according to comparative examples 1 to 2 after the heat treatment. Meanwhile, compared with the high strength and toughness seamless steel tube for motor shafts in examples 1-10 before the tempering heat treatment, the yield strength and the tensile strength of the high strength and toughness seamless steel tube after the tempering heat treatment are obviously improved, and the elongation A 50 Accordingly, it descends.
As can be seen from Table 4, the high strength and toughness seamless steel pipes for motor shafts of examples 1 to 10 obtained by the present invention all have excellent mechanical properties, and the yield strength R thereof p0.2 Between 1059 and 1169MPa, and has tensile strength R m The elongation is between 9 and 15 percent between 1400 and 1766MPa, and the strong plasticity R thereof m ×A 50 Between 15499-24724MPa%, hardness between 59-64HRC, and torsion resistance between 346-597 KN.
In comparison with examples 1 to 10, in comparative examples 1 to 2, chemical components and/or processes which do not meet the design requirements of the present invention are present, and the design is such that at least one mechanical property of the comparative steel pipe manufactured in comparative examples 1 to 2 does not meet the requirements of the present invention. As shown in table 4, the torsional properties of comparative example 1 and comparative example 2 were lower than those of examples 1 to 10.
Furthermore, after completion of the above-mentioned detection of mechanical properties, the inventors also sampled the steel pipes of examples 1 to 10 and comparative examples 1 to 2 after heat treatment, and observed and analyzed the microstructure thereof, and the results of the relevant observation and analysis are shown in Table 5 below.
Table 5 shows the microstructure observation and analysis results of the high strength and toughness seamless steel pipes for motor shafts of examples 1 to 10 and the comparative steel pipes of comparative examples 1 to 2 after the heat treatment by tempering.
Table 5.
As can be seen from the above Table 5, after the tempering heat treatment, the high strength and toughness seamless steel pipes for motor shafts of examples 1 to 10 all obtained microstructures of martensite+retained austenite, and the volume phase ratio of the retained austenite was specifically 3 to 24%.
It should be noted that the combination of the technical features in the present invention is not limited to the combination described in the claims or the combination described in the specific embodiments, and all the technical features described in the present invention may be freely combined or combined in any manner unless contradiction occurs between them.
It should also be noted that the above-recited embodiments are merely specific examples of the present invention. It is apparent that the present invention is not limited to the above embodiments, and similar changes or modifications will be apparent to those skilled in the art from the present disclosure, and it is intended to be within the scope of the present invention.

Claims (14)

1. A high-strength and high-toughness seamless steel tube for a motor shaft with good processability contains Fe and unavoidable impurity elements and is characterized by also containing the following chemical elements in percentage by mass:
C：0.40～0.60％，0＜Si≤0.25％，Mn：0.5～1.2％，Ti≤0.045％，B≤0.0045％，N：0.0040～0.009％，Al：0.015～0.045％,Ca+Mg：0.001～0.006％。
2. the high-strength and high-toughness seamless steel pipe for a motor shaft according to claim 1, wherein the mass percentages of the chemical elements are as follows:
c: 0.40-0.60%, si is more than 0 and less than or equal to 0.25%, mn:0.5 to 1.2 percent, ti is less than or equal to 0.045 percent, B is less than or equal to 0.0045 percent, N: 0.0040-0.009%, al:0.015 to 0.045 percent, ca+Mg:0.001 to 0.006 percent; the balance being Fe and unavoidable impurities.
3. The high-strength and high-toughness seamless steel pipe for motor shafts according to claim 1 or 2, wherein among unavoidable impurities, P is 0.020% or less, S is 0.008% or less, and O is 0.0030% or less.
4. The high-strength and high-toughness seamless steel pipe for motor shafts according to claim 3, wherein among the unavoidable impurities, P is not more than 0.015%, S is not more than 0.005%, and O is not more than 0.0025%.
5. The high-strength and high-toughness seamless steel pipe for motor shafts according to claim 1 or 2, wherein the mass percentage of each chemical element further satisfies at least one of the following:
C：0.45～0.55％，
0＜Si≤0.20％，
Mn：0.6～1.0％，
Ti：0.02～0.04％，
B：0.002～0.004％，
N：0.0045～0.0085％,
Al：0.015～0.035％,
Ca+Mg：0.001～0.004％。
6. the high-strength and high-toughness seamless steel pipe for motor shafts according to claim 1 or 2, wherein the microstructure thereof is ferrite+pearlite.
7. The high-strength and high-toughness seamless steel pipe for motor shafts according to claim 1 or 2, wherein the microstructure thereof subjected to the tempering heat treatment is martensite and retained austenite having a volume phase ratio of 1 to 25%.
8. The high-strength and high-toughness seamless steel pipe for motor shafts according to claim 1 or 2, characterized in that the yield strength Rp thereof 0.2 Not less than 400MPa, tensile strength R m 550MPa or more, elongation A 50 ≥22％。
9. The high-strength and high-toughness seamless steel pipe for motor shafts according to claim 1 or 2, characterized in that the properties after heat treatment by tempering satisfy: yield strength Rp 0.2 Not less than 1000MPa, tensile strength R m Not less than 1400MPa, elongation A 50 More than or equal to 5 percent, the hardness is more than or equal to 58HRC, the product of strength and elongation is more than 15000MPa, and the torsion resistance is more than or equal to 300KN.
10. A method for manufacturing a high-strength seamless steel pipe for a motor shaft according to any one of claims 1 to 9, comprising the steps of:
(1) Preparing a tube blank;
(2) Heating, perforating, hot rolling and reducing;
(3) Intermediate heat treatment: annealing the hot rolled pipe material at the temperature of 650-800 ℃ for 20-80 min;
(4) Cold drawing;
(5) And (3) heat treatment of a finished product: normalizing at 750-820 deg.c for 20-60 min to obtain ferrite-pearlite structure.
11. The method according to claim 10, wherein in the step (2), the tube blank is heated at 1210 to 1280 ℃ and kept for 30 to 150 minutes.
12. The method according to claim 10, wherein in the step (2), the perforation temperature is controlled to 1150 to 1250 ℃.
13. The method according to claim 10, wherein in the step (2), the hot continuous rolling temperature is controlled to 1000 to 1200 ℃.
14. The method according to claim 10, wherein in the step (2), the temperature of the sheet is controlled to be 950 to 1000 ℃.
CN202210711762.7A 2022-06-22 2022-06-22 High-strength and high-toughness seamless steel tube for motor shaft with good processability and manufacturing method thereof Pending CN117305684A (en)

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