CN115125440A - Preparation method of high-performance steel strip for long-fatigue-life transmission shaft pipe - Google Patents

Preparation method of high-performance steel strip for long-fatigue-life transmission shaft pipe Download PDF

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Publication number
CN115125440A
CN115125440A CN202210679434.3A CN202210679434A CN115125440A CN 115125440 A CN115125440 A CN 115125440A CN 202210679434 A CN202210679434 A CN 202210679434A CN 115125440 A CN115125440 A CN 115125440A
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controlled
transmission shaft
cooling
rolling
fatigue
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CN202210679434.3A
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CN115125440B (en
Inventor
张继永
李守华
张义春
李红俊
周建川
姚政
李爱民
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Handan Iron and Steel Group Co Ltd
HBIS Co Ltd Handan Branch
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Handan Iron and Steel Group Co Ltd
HBIS Co Ltd Handan Branch
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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C33/00—Making ferrous alloys
    • C22C33/04—Making ferrous alloys by melting
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B1/00—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations
    • B21B1/46—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling metal immediately subsequent to continuous casting
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B15/00—Arrangements for performing additional metal-working operations specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B37/00—Control devices or methods specially adapted for metal-rolling mills or the work produced thereby
    • B21B37/48—Tension control; Compression control
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B37/00—Control devices or methods specially adapted for metal-rolling mills or the work produced thereby
    • B21B37/74—Temperature control, e.g. by cooling or heating the rolls or the product
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/001—Continuous casting of metals, i.e. casting in indefinite lengths of specific alloys
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C7/0006—Adding metallic additives
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C7/0056—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00 using cored wires
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C7/04—Removing impurities by adding a treating agent
    • C21C7/064—Dephosphorising; Desulfurising
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C7/10—Handling in a vacuum
    • 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
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0205—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips 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
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
    • C21D8/0226—Hot rolling
    • 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
    • C22C38/06—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
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/24—Ferrous alloys, e.g. steel alloys containing chromium with vanadium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/26—Ferrous alloys, e.g. steel alloys containing chromium with niobium or tantalum
    • 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
    • C22C38/28—Ferrous alloys, e.g. steel alloys containing chromium with 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
    • C22C38/38—Ferrous alloys, e.g. steel alloys containing chromium with more than 1.5% by weight of manganese
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B15/00—Arrangements for performing additional metal-working operations specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills
    • B21B2015/0057—Coiling the rolled product
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/002—Bainite

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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)
  • Treatment Of Steel In Its Molten State (AREA)

Abstract

The invention discloses a preparation method of a high-performance steel belt for a long-fatigue-life transmission shaft pipe, and belongs to the technical field of metallurgical rolling. The preparation method comprises the following steps: the method comprises the working procedures of molten iron pretreatment, converter smelting, refining, slab continuous casting, slab heating, controlled rolling, controlled cooling and coiling, wherein the ultimate vacuum degree in the RH working procedure is less than or equal to 1.0mbar, the vacuum circulation time is 15-50min, the net blowing time is 6-20min, the soft blowing time is prolonged to 10-15min after the molten iron is taken out of a station, and the molten iron is kept still for 10-50 min. In the controlled cooling and coiling processes, ultra-fast cooling and front-section intensive cooling are adopted in post-rolling cooling, the water temperature is controlled to be 20-30 ℃, and the cooling speed is controlled to be 40-150 ℃/s. The steel strip produced by the invention has the characteristics of high strength, light weight, good toughness, excellent welding performance, excellent cold-bending pipe making performance and the like, and meets the requirements of the field of automobile transmission shaft pipes on high-performance, long service life and light steel.

Description

Preparation method of high-performance steel strip for long-fatigue-life transmission shaft pipe
Technical Field
The invention belongs to the technical field of metallurgical rolling, and particularly relates to a preparation method of a high-performance steel belt for a long-fatigue-life transmission shaft pipe.
Background
The automobile transmission shaft is an important force transmission part for vehicle running, and the power output by the engine is transmitted to wheels through a speed reducer, a gearbox, a transmission shaft, a differential and a drive axle to drive the vehicle to run. In order to reduce the weight of a vehicle body, save the manufacturing cost and reduce the oil consumption, a modern automobile transmission shaft is generally manufactured by adopting a straight seam resistance welded pipe (ERW) process, and a steel belt for manufacturing the pipe is required to have high strength and light weight, and also needs to have good welding performance, cold bending performance and lower welding crack sensitivity. Meanwhile, the transmission shaft of the automobile bears complex stress such as torsion, bending, impact and the like when the automobile runs on roads with different environmental temperatures and different working conditions, and the material is required to have high strength and good low-temperature impact resistance, bending performance and long torsion cycle life.
The automobile transmission shaft which is widely used in the market and is made of 650MPa transmission shaft steel has the problems of heavy structure, limited strength and low-temperature impact toughness, short torsional cycle life and the like. Under the current background of the development of the era with energy conservation, emission reduction, environmental protection and high efficiency, the automobile transmission shaft tube is bound to develop towards the direction of higher strength, better performance and longer service life in the future.
The patent with the publication number of CN109504898A discloses 'a hot-rolled steel strip for an automobile transmission shaft pipe with the yield strength of 3-8mm and the level of 700MPa and a production method thereof', which comprises the following chemical components in percentage: c: 0.06-0.08%, Si: 0.05-0.15%, Mn: 1.50-1.70%, P is less than or equal to 0.015%, S is less than or equal to 0.010%, Alt: 0.020 to 0.060%, Nb: 0.025-0.035%, Ti: 0.070-0.090%, Ca: 0.0010-0.0030%, Ce: 0.0005-0.0020%, the balance being iron and unavoidable impurities. The patent adopts Nb and Ti composite additive component design, and adds a proper amount of rare earth elements to improve the purity of molten steel and improve the comprehensive performance of steel. The production process selects a conventional long-flow manufacturing process comprising molten iron pretreatment, converter smelting, LF and RH double refining, continuous casting, slab heating, rolling, cooling and coiling, the low-carbon environmental protection technology is generally applied, the control method is common, the metallographic microstructure of the transmission shaft tube produced according to the process is ferrite plus pearlite, the actual yield strength of the produced steel strip is 695 plus 712MPa, the tensile strength is 749 plus 764MPa, the elongation is 17.3-20.5%, the strength of the material is not high, and the plastic elongation is limited.
Patent publication No. CN109763063A discloses "an alloy structural steel suitable for use as a high-strength drive shaft", which comprises the following components by weight percent: c: 0.22-0.28%, Si: 0.10-0.30%, Mn: 0.50-0.80%, P is less than or equal to 0.005%, S is less than or equal to 0.002%, Cr: 0.80-1.60%, Ni: 1.50-2.50%, Mo: 0.15-0.35%, V: 0.10-0.25%, Nb is less than or equal to 0.10%, O is less than or equal to 0.0020%, H is less than or equal to 0.0002%, N is less than or equal to 0.0050%, RE: 0.0010-0.0035% and the balance of Fe and inevitable impurities. The invention mainly applies a component design, adds a large amount of expensive alloys such as Cr, Ni, Mo, rare earth elements and the like into the steel in order to improve the hardenability and low-temperature toughness of the steel, increases the production and manufacturing cost, and has the metallographic microscope mainly based on martensite, the tensile strength of more than 1500MPa, the elongation of only 12-14 percent, difficult processing and forming and is not beneficial to large-scale production and popularization.
The patent with the publication number of CN111187991A discloses 'a special steel for an automobile transmission shaft tube and a preparation method thereof', which comprises the following components by weight percent: c: 0.05 to 0.12 percent; si: 0.05 to 0.25%, Mn: 1.40-1.70%, Nb: 0.005-0.05%, P is less than or equal to 0.015%, O is less than or equal to 0.0020%, N is less than or equal to 0.0040%, S is less than or equal to 0.005%, Ti: 0.05-0.15%, V: 0.02-0.10%, and the balance of iron and inevitable impurities. The invention mainly relates to a smelting method of a transmission shaft tube, which carries out quantitative specification on the ratio of magnesium powder and lime powder in a pretreatment process, the slag amount in converter tapping and the addition of a deoxidizer in a refining process, and plays a certain role in reducing harmful elements such as P, S in molten steel and improving the purity of the molten steel. But the rolling procedure and the subsequent tube making process are not involved, the performance of the final finished product expressed by the method is 690-760 MPa in yield strength, 780-825 MPa in tensile strength, fatigue life is increased to more than 10 ten thousand times, the total performance is sufficient at present, and the development requirement of the light-weight transmission shaft tube steel with long cycle life of more than 100 ten thousand times at the 800MPa level in the future cannot be met.
Disclosure of Invention
The invention aims to solve the technical problem of providing a preparation method of a high-performance steel strip for a long-fatigue-life transmission shaft tube, and meeting the requirements of the field of automobile transmission shaft tubes on high-performance, long-life and light-weight steel.
In order to solve the technical problems, the invention adopts the technical scheme that: long fatigue lifeThe preparation method of the high-performance steel strip for the transmission shaft pipe comprises the working procedures of molten iron pretreatment, converter smelting, refining, plate blank continuous casting, plate blank heating, controlled rolling, controlled cooling and reeling; in the refining process, the ultimate vacuum degree in the RH process is less than or equal to 1.0mbar, the vacuum circulation time is 15-50min, the net blowing time is 6-20min, the soft blowing time is prolonged to 10-15min after the refining process is out of the station, and the refining process is kept still for 10-50 min; the cooling and coiling processes are controlled, ultra-fast cooling and front-section intensive cooling are adopted in the cooling after rolling, the water temperature is controlled to be 20-30 ℃, the cooling speed is controlled to be 40-150 ℃/s, the strip steel is cooled to 350-550 ℃ for coiling, and the tension in the coiling process is controlled to be 80N/mm 2 The above.
The invention controls the rolling procedure, the rough rolling procedure, the rolling starting temperature is 1080-; the finish rolling procedure comprises the inlet temperature of the finish rolling is 900-1050 ℃, the accumulated reduction rate of the finish rolling is controlled to be 50-85%, the reduction rate of the frame at the end of the finish rolling is 8-15%, and the finishing temperature is 820-910 ℃.
In the slab continuous casting process, argon protection pouring is carried out in the whole process, the superheat degree of a tundish is controlled at 10-24 ℃, the casting is kept at a stable casting speed, the casting speed is controlled at 0.9-2.4m/min, and the fluctuation of the liquid level is controlled within +/-3 mm. The secondary cooling water amount of the continuous casting is manually increased by 10-25 percent on the original basis, the quantity and the size of TiN precipitated are controlled, and the solidification tail end of a casting blank is dynamically and lightly pressed, wherein the reduction is more than or equal to 4 mm.
The molten iron pretreatment process adopts a magnesium powder and limestone composite blowing process, and the weight ratio of the magnesium powder to the limestone is as follows: 1: 2.5-5.2.
The refining process adopts an LF + RH double refining mode, wherein the LF process adopts a deep desulfurization mode for treatment, the S content of the outbound molten steel is less than or equal to 0.008 percent, and calcium wires are fed 5min before the smelting is finished to perform modification treatment on the inclusions.
The converter smelting process adopts a top-bottom combined blowing smelting process, slag is formed by lime and dolomite, the slag amount of tapping is controlled by a sliding plate slag blocking and infrared slag tapping detection technology during tapping, and the end point P is controlled to be below 0.015%.
In the slab heating process, the heating furnace is kept at micro-positive pressure of 3-15Pa, the air-fuel ratio is 0.95-1.45, the slab discharging temperature is 1300 ℃ according to 1220-.
The high-performance steel strip for the transmission shaft pipe comprises the following chemical components in percentage by weight: c: 0.03% -0.10%, Si: 0.03% -0.30%, Mn: 1.60-2.40%, P is less than or equal to 0.020%, S is less than or equal to 0.006%, Als: 0.015% -0.050%, Nb: 0.040% -0.078%, V: 0.040% -0.090%, Ti: 0.030% -0.080%, Cr: 0.15 to 0.55 percent of the total weight of the alloy, less than or equal to 0.0060 percent of N, and the balance of Fe and inevitable residual elements.
The high-performance steel strip for the transmission shaft tube has the yield strength of more than or equal to 800MPa, the tensile strength of 900-1100MPa, the elongation of more than or equal to 21 percent, the yield ratio of less than or equal to 0.90 and the total content of non-metallic inclusions of less than or equal to 3.0, and the torsional fatigue cycle life of more than or equal to 150 ten thousand times after the transmission shaft tube is manufactured.
The invention adopts unconventional technical means in the processes of controlling cooling and coiling and refining to obtain the steel strip for the transmission shaft with pure steel quality, low content of non-metallic inclusions and excellent structure performance, and the main basis of the formulation process is as follows:
1. controlled cooling process
The process of ultra-fast cooling and front-section intensive cooling is adopted in the controlled cooling procedure, and the main purpose is to obtain larger cooling through front-section ultra-fast cooling, inhibit austenite grains from growing large, and obtain fine finished product tissues to improve the comprehensive mechanical property of the steel. The water temperature is a main factor for determining the laminar cooling efficiency, the cooling efficiency is low when the water temperature is too high, the number of the laminar cooling collecting pipe groups is limited, and the designed cooling speed cannot be reached even if the collecting pipe water is fully opened; the setting and self-learning of the secondary layer cooling model are influenced by the too low water temperature, the hit rate of the coiling temperature is influenced, and therefore, the water temperature is preferably controlled to be 20-30 ℃.
The cooling speed and the coiling temperature determine the cooling process path and the metallographic structure type of a finished product, if the cooling speed is too low, the finished product enters a ferrite-pearlite transformation interval, if the cooling speed is too high, an overhigh requirement is put on a layer cooling device, the device investment cost is increased, otherwise, if the cooling speed is too high, the structure enters a martensite transformation interval, and the coiling temperature is the final cooling temperature and influences the microstructure type of the finished product. The metallographic structure required to be obtained by the method is lath-shaped or needle-shaped bainite structure. Therefore, the cooling rate is preferably controlled to be 40-150 ℃/s and the coiling temperature is controlled to be 350-550 ℃ according to the design of components and performance requirements.
2. Coiling step
The steel designed by the invention has high strength and large thermal deformation resistance, and is required to have enough coiling tension in the coiling process, otherwise, the defects of poor coiling shape such as dislocation of coiling layers, flat coiling, uncoiling and the like are easily caused. Therefore, in the coiling process, the tension in the coiling process is required to be controlled to 80N/mm according to the steel grade characteristics and the capacity of the coiling equipment 2 As described above.
3. Refining procedure
An LF + RH double refining mode is adopted in the refining process, wherein a deep desulfurization mode is adopted in the LF process for treatment, the condition that S is less than or equal to 0.008% after leaving the station is ensured, and if a calcium wire is fed early in smelting, the calcium wire is volatile in smelting, and the effect of denaturation of impurities cannot be achieved; and the calcium wire is fed too late in smelting, so that the calcium wire is not uniformly melted, and new inclusions are formed in molten steel. Therefore, it is preferable to feed the calcium wire 5min before the end of the smelting. The RH smelting process ensures the vacuum degree to prevent external air from entering, simultaneously takes the vacuumizing capacity of the existing equipment into consideration, preferably the limit vacuum degree is less than or equal to 1.0mbar, and the RH vacuum smelting aims to realize the purpose of pure degassing circulation for a long time through an RH furnace, and soft blowing and standing are carried out after the RH furnace is out of service so that oxide impurities in the molten steel can be fully floated and purified. Considering the rhythm control of smelting production, preferably the RH vacuum cycle time is controlled to be 15-50min, the net blowing time is 6-20min, the soft blowing time is prolonged to 10-15min after the molten steel is out of the station, and the molten steel is kept still for 10-50 min.
Adopt the produced beneficial effect of above-mentioned technical scheme to lie in:
1. the invention adopts proper component design, avoids adding precious alloys such as Mo, Ni, rare earth and the like, combines the ultra-fast cooling and front-section intensive cooling process, obtains fine and uniform lath-shaped or needle-shaped bainite tissues on line in a hot rolling procedure, does not need off-line heat treatment, reduces the energy consumption of the procedure and improves the production efficiency.
2. In the smelting process, the adding time of the calcium wire is accurately controlled, the technological parameters such as RH vacuum cycle time, net blowing time, standing time and the like are quantized, harmful elements such as P, S in steel are effectively controlled, the non-metallic inclusions in molten steel are fully floated and removed, the steel quality is pure, and the total content of the non-metallic inclusions in the final finished product is controlled within 3.0 level.
3. The steel for the transmission shaft pipe has the characteristics of high strength, light weight, good toughness, excellent welding performance and cold-bending pipe manufacturing performance and the like, and has the yield strength of more than or equal to 800MPa, the tensile strength of 900-1100MPa, the elongation of more than or equal to 21 percent and the yield ratio of less than or equal to 0.90. The service life of the torsional fatigue cycle after the automobile transmission shaft tube is manufactured reaches more than 150 ten thousand times, the automobile transmission shaft tube can be in service safely under complex working conditions of bending, twisting, impacting and the like, and the requirements of the field of automobile transmission shaft tubes on high-performance, long-service life and light steel are met.
Detailed Description
The present invention will be described in further detail with reference to specific examples.
Example 1
A preparation method of a high-performance steel strip for a long-fatigue-life transmission shaft tube comprises the working procedures of molten iron pretreatment, converter smelting, refining, slab continuous casting, slab heating, controlled rolling, controlled cooling and reeling. The specific procedures are as follows:
1) the molten iron pretreatment process adopts a magnesium powder and limestone composite blowing process, and the weight ratio of the magnesium powder to the limestone is as follows: 1:3.8.
2) A converter smelting process: the top-bottom combined blowing smelting process is adopted, slag is formed by lime and dolomite, the slag amount of tapping is controlled by a sliding plate slag blocking and infrared slag discharging detection technology during tapping, and the end point P is controlled to be 0.012%.
3) A refining procedure: adopting an LF + RH double refining mode, wherein a deep desulfurization mode is adopted in an LF process for treatment, the S content of the product discharged from the station is 0.004%, and calcium wires are fed 5min before the smelting is finished to perform denaturation treatment on the impurities; and in the RH process, the ultimate vacuum degree is less than or equal to 1.0mbar, the vacuum cycle time is 26min, the net blowing time is 8min, the soft blowing time is prolonged to 12min after the product is taken out of the station, and the product is kept stand for 32 min.
4) And a slab continuous casting process: in the process of pouring molten steel, argon is used for protecting pouring, the degree of superheat of a tundish is 18 ℃, the casting is kept at a stable drawing speed, the drawing speed is controlled at 0.12m/min, and the fluctuation of the liquid level is controlled within +/-3 mm. The secondary cooling water amount of the continuous casting is manually increased by 20 percent on the original basis, the quantity and the size of TiN precipitated are controlled, and the dynamic soft reduction is carried out on the solidification tail end of a casting blank, wherein the reduction amount is 6 mm.
5) And a slab heating process, wherein a heating furnace maintains 4.5Pa micro positive pressure, the air-fuel ratio is 0.98, the tapping temperature of the slab is 1255 ℃, the heating time is 200min, and the tail temperature of the slab is increased by 23 ℃ for improving the subsequent rolling stability.
6) And (3) controlling a rolling process: wherein the initial rolling temperature of the rough rolling procedure is 1188 ℃, the accumulated reduction rate is controlled at 92 percent, and the final two-pass reduction rate is 23 percent and 25 percent respectively; in the finish rolling process, the inlet temperature of finish rolling is 1028 ℃, the cumulative reduction rate of finish rolling is 82%, the reduction rate of a finish rolling final stand is 11%, and the finish rolling temperature is 886 ℃.
7) Controlling the cooling and coiling processes: the ultra-fast cooling and the front-section intensive cooling are adopted in the cooling after rolling, the water temperature is required to be controlled at 24 ℃, the cooling speed is controlled at 55 ℃/s, the strip steel is cooled to 364 ℃ for coiling, the tension in the coiling process is controlled at 89N/mm 2 。
The specific chemical component content and the performance of the high-performance steel strip for the long-fatigue-life transmission shaft pipe obtained in the embodiment are shown in table 1 and table 2.
Example 2
A preparation method of a high-performance steel strip for a long-fatigue-life transmission shaft tube comprises the working procedures of molten iron pretreatment, converter smelting, refining, slab continuous casting, slab heating, controlled rolling, controlled cooling and reeling. The specific procedures are as follows:
1) the molten iron pretreatment process adopts a magnesium powder and limestone composite blowing process, and the weight ratio of the magnesium powder to the limestone is as follows: 1:2.5.
2) A converter smelting process: the top-bottom combined blowing smelting process is adopted, lime and dolomite are used for slagging, a sliding plate slag blocking and infrared slag tapping detection technology is used during steel tapping, the slag tapping amount is controlled, and the terminal point P is controlled to be 0.010%.
3) A refining procedure: adopting an LF + RH double refining mode, wherein a deep desulfurization mode is adopted in an LF process for treatment, the S content of an outlet station is 0.008%, and calcium wires are fed 5min before smelting to perform modification treatment on the inclusions; in the RH process, the ultimate vacuum degree is less than or equal to 1.0mbar, the vacuum cycle time is 18min, the net blowing time is 14min, the soft blowing time is prolonged to 10min after the operation is finished, and the operation is kept stand for 15 min.
4) And a slab continuous casting process: in the process of pouring molten steel, argon is used for protecting pouring, the superheat degree of a tundish is 12 ℃, the pulling speed is kept stable in pouring, the pulling speed is controlled to be 2.0m/min, and the liquid level fluctuation is controlled to be within +/-3 mm. The secondary cooling water amount of the continuous casting is manually increased by 18 percent on the original basis, the quantity and the size of TiN precipitated are controlled, and the solidification tail end of a casting blank is dynamically and lightly pressed down by 5 mm.
5) And a slab heating process, wherein the heating furnace keeps 3.0Pa micro-positive pressure control, the air-fuel ratio is 1.25, the slab discharging temperature is 1247 ℃, the heating time is 168min, and the temperature of the tail of the slab is increased by 18 ℃ for improving the subsequent rolling stability.
6) And (3) controlling a rolling process: wherein the initial rolling temperature of the rough rolling procedure is 1171 ℃, the accumulated reduction rate is controlled to be 70 percent, and the final two-pass reduction rate is respectively 20 percent and 23 percent; in the finish rolling process, the inlet temperature of finish rolling is 984 ℃, the cumulative reduction rate of finish rolling is controlled according to 78%, the reduction rate of a finish rolling final rack is 10%, and the final rolling temperature is 844 ℃.
7) Controlling the cooling and coiling processes: the ultra-fast cooling and the front-section intensive cooling are adopted in the cooling after rolling, the water temperature is required to be controlled at 20 ℃, the cooling speed is controlled at 78 ℃/s, the strip steel is cooled to 358 ℃ for coiling, the tension in the coiling process is controlled at 95N/mm 2 。
The specific chemical component content and the performance of the high-performance steel strip for the long-fatigue-life transmission shaft pipe obtained in the embodiment are shown in table 1 and table 2.
Example 3
A preparation method of a high-performance steel strip for a long-fatigue-life transmission shaft pipe comprises the working procedures of molten iron pretreatment, converter smelting, refining, slab continuous casting, slab heating, controlled rolling, controlled cooling and coiling. The specific procedures are as follows:
1) the molten iron pretreatment process adopts a magnesium powder and limestone composite blowing process, and the weight ratio of the magnesium powder to the limestone is as follows: 1:4.4.
2) A converter smelting process: the top-bottom combined blowing smelting process is adopted, slag is formed by lime and dolomite, the slag amount of tapping is controlled by a sliding plate slag blocking and infrared slag discharging detection technology during tapping, and the end point P is controlled to be 0.015%.
3) A refining procedure: adopting an LF and RH double refining mode, wherein a deep desulfurization mode is adopted in an LF process for treatment, the S content of an outlet station is 0.002%, and calcium wires are fed 5min before smelting is finished to perform modification treatment on the inclusions; and in the RH process, the ultimate vacuum degree is less than or equal to 1.0mbar, the vacuum cycle time is 24min, the net blowing time is 6min, the soft blowing time is prolonged to 13min after the product is taken out of the station, and the product is kept stand for 21 min.
4) And a slab continuous casting process: in the process of pouring molten steel, argon is used for protecting pouring, the superheat degree of a tundish is 15 ℃, the stable drawing speed is kept in pouring, the drawing speed is controlled to be 0.9m/min, and the liquid level fluctuation is controlled to be within +/-3 mm. The secondary cooling water amount of the continuous casting is manually increased by 10 percent on the original basis, the quantity and the size of TiN precipitated are controlled, and the solidification tail end of a casting blank is dynamically and lightly pressed down by 5 mm.
5) And a slab heating process, wherein the heating furnace maintains micro-positive pressure of 8.3Pa, the air-fuel ratio is 0.95, the tapping temperature of the slab is 1220 ℃, the heating time is 242min, and the tail temperature of the slab is increased by 12 ℃ for improving the subsequent rolling stability.
6) And (3) controlling a rolling process: wherein the initial rolling temperature of the rough rolling procedure is 1080 ℃, the cumulative reduction rate is controlled to be 95 percent, and the final two-pass reduction rate is respectively 26 percent and 38 percent; in the finish rolling process, the inlet temperature of finish rolling is 900 ℃, the cumulative reduction rate of finish rolling is 50%, the reduction rate of a last stand of the finish rolling is 12%, and the finish rolling temperature is 859 ℃.
7) Controlling the cooling and coiling processes: the ultra-fast cooling and the front section intensive cooling are adopted in the cooling after rolling, the water temperature is required to be controlled at 28 ℃, the cooling speed is controlled at 123 ℃/s, the strip steel is cooled to 516 ℃ for coiling, and the tension in the coiling process is controlled at 80N/mm 2 。
The specific chemical component contents of the high-performance steel strip for the long-fatigue-life transmission shaft pipe obtained in the embodiment are shown in table 1, and the performances are shown in table 2.
Example 4
A preparation method of a high-performance steel strip for a long-fatigue-life transmission shaft pipe comprises the working procedures of molten iron pretreatment, converter smelting, refining, slab continuous casting, slab heating, controlled rolling, controlled cooling and coiling. The specific procedures are as follows:
1) the molten iron pretreatment process adopts a magnesium powder and limestone composite blowing process, and the weight ratio of the magnesium powder to the limestone is as follows: 1:4.5.
2) A converter smelting process: the top-bottom combined blowing smelting process is adopted, slag is formed by lime and dolomite, the slag amount of tapping is controlled by a sliding plate slag blocking and infrared slag falling detection technology during tapping, and the end point P is controlled to be 0.011 percent.
3) A refining procedure: adopting an LF + RH double refining mode, wherein a deep desulfurization mode is adopted in an LF process for treatment, the S content of an outlet is 0.006%, and calcium wires are fed 5min before smelting is finished to perform denaturation treatment on the inclusions; and in the RH process, the ultimate vacuum degree is less than or equal to 1.0mbar, the vacuum cycle time is 15min, the net blowing time is 10min, the soft blowing time is prolonged to 15min after the product is taken out of the station, and the product is kept stand for 42 min.
4) And a slab continuous casting process: in the process of pouring molten steel, argon is used for protecting pouring, the degree of superheat of a tundish is 10 ℃, the pulling speed is kept stable in pouring, the pulling speed is controlled to be 1.5m/min, and the fluctuation of the liquid level is controlled to be within +/-3 mm. The secondary cooling water amount of the continuous casting is manually increased by 13 percent on the original basis, the quantity and the size of TiN precipitated are controlled, and the solidification tail end of a casting blank is dynamically and lightly pressed down by 4 mm.
5) And a slab heating process, wherein the heating furnace keeps 6.8Pa micro positive pressure, the air-fuel ratio is 1.45, the tapping temperature of the slab is 1245 ℃, the heating time is 350min, and the tail temperature of the slab is increased by 10 ℃ in order to improve the subsequent rolling stability.
6) And (3) controlling a rolling process: wherein the initial rolling temperature of the rough rolling procedure is 1200 ℃, the accumulated reduction rate is controlled to be 84%, and the final two-pass reduction rate is respectively 21% and 24%; in the finish rolling process, the inlet temperature of finish rolling is 985 ℃, the cumulative reduction rate of finish rolling is controlled according to 67 percent, the reduction rate of a finish rolling end stand is 11 percent, and the finish rolling temperature is 905 ℃.
7) Controlling the cooling and coiling processes: the ultra-fast cooling and the front-section intensive cooling are adopted in the cooling after rolling, the water temperature is required to be controlled at 28 ℃, the cooling speed is controlled at 40 ℃/s, the strip steel is cooled to 350 ℃ for coiling, the tension in the coiling process is controlled at 108N/mm 2 。
The specific chemical component content and the performance of the high-performance steel strip for the long-fatigue-life transmission shaft pipe obtained in the embodiment are shown in table 1 and table 2.
Example 5
A preparation method of a high-performance steel strip for a long-fatigue-life transmission shaft pipe comprises the working procedures of molten iron pretreatment, converter smelting, refining, slab continuous casting, slab heating, controlled rolling, controlled cooling and coiling. The specific procedures are as follows:
1) the molten iron pretreatment process adopts a magnesium powder and limestone composite blowing process, and the weight ratio of the magnesium powder to the limestone is as follows: 1:5.2.
2) A converter smelting process: the top-bottom combined blowing smelting process is adopted, lime and dolomite are used for slagging, a sliding plate is used for blocking slag and an infrared deslagging detection technology is used during tapping, the deslagging amount during tapping is controlled, and the terminal point P is controlled to be 0.009%.
3) A refining procedure: an LF and RH double refining mode is adopted, wherein a deep desulfurization mode is adopted in an LF process for treatment, the S content of the product discharged from a station is 0.005%, and calcium wires are fed 5min before smelting is finished to perform denaturation treatment on the impurities; in the RH process, the ultimate vacuum degree is less than or equal to 1.0mbar, the vacuum circulation time is 50min, the net blowing time is 18min, the soft blowing time is prolonged to 12min after the operation is finished, and the operation is kept still for 10 min.
4) And a slab continuous casting process: in the process of pouring molten steel, argon is used for protecting pouring in the whole process, the superheat degree of the tundish is 24 ℃, the pulling speed is kept stable in pouring, the pulling speed is controlled at 2.4m/min, and the liquid level fluctuation is controlled within +/-3 mm. The secondary cooling water amount of the continuous casting is manually increased by 12 percent on the original basis, the quantity and the size of TiN precipitated are controlled, and the dynamic soft reduction is carried out on the solidification tail end of a casting blank, wherein the reduction amount is 8 mm.
5) And a slab heating process, wherein a heating furnace maintains micro positive pressure of 9.8Pa, the air-fuel ratio is 1.12, the slab tapping temperature is 1268 ℃, the heating time is 284min, and the temperature of the tail of the slab is increased by 40 ℃ in order to improve the subsequent rolling stability.
6) And (3) controlling a rolling process: wherein the initial rolling temperature of the rough rolling procedure is 1175 ℃, the accumulated reduction rate is controlled to be 92 percent, and the final reduction rates of the two passes are respectively 24 percent and 28 percent; in the finish rolling process, the inlet temperature of finish rolling is 998 ℃, the cumulative reduction rate of finish rolling is 85%, the reduction rate of a finish rolling last stand is 15%, and the finish rolling temperature is 820 ℃.
7) Controlling the cooling and coiling processes: the ultra-fast cooling and the front-section intensive cooling are adopted in the cooling after rolling, the water temperature is required to be controlled at 30 ℃, the cooling speed is controlled at 95 ℃/s, the strip steel is cooled to 524 ℃ for coiling, and the tension in the coiling process is controlled at 95N/mm 2 。
The specific chemical component content and the performance of the high-performance steel strip for the long-fatigue-life transmission shaft pipe obtained in the embodiment are shown in table 1 and table 2.
Example 6
A preparation method of a high-performance steel strip for a long-fatigue-life transmission shaft tube comprises the working procedures of molten iron pretreatment, converter smelting, refining, slab continuous casting, slab heating, controlled rolling, controlled cooling and reeling. The specific procedures are as follows:
1) the molten iron pretreatment process adopts a magnesium powder and limestone composite blowing process, and the weight ratio of the magnesium powder to the limestone is as follows: 1:3.8.
2) A converter smelting process: the top-bottom combined blowing smelting process is adopted, slag is formed by lime and dolomite, the slag amount of tapping is controlled by a sliding plate slag blocking and infrared slag discharging detection technology during tapping, and the end point P is controlled to be 0.015%.
3) A refining procedure: adopting an LF + RH double refining mode, wherein a deep desulfurization mode is adopted in an LF process for treatment, the S content of an outlet is 0.001%, and calcium wires are fed 5min before smelting to perform denaturation treatment on the impurities; and in the RH process, the ultimate vacuum degree is less than or equal to 1.0mbar, the vacuum cycle time is 38min, the net blowing time is 17min, the soft blowing time is prolonged to 10min after the terminal is out of the station, and the terminal is kept still for 50 min.
4) A slab continuous casting process: in the process of pouring molten steel, argon is used for protecting pouring, the degree of superheat of a tundish is 14 ℃, the stable drawing speed is kept in pouring, the drawing speed is controlled to be 1.8m/min, and the fluctuation of the liquid level is controlled to be within +/-3 mm. The secondary cooling water amount of the continuous casting is manually increased by 24 percent on the original basis, the quantity and the size of TiN precipitated are controlled, and the dynamic soft reduction is carried out on the solidification tail end of the casting blank, wherein the reduction amount is 8 mm.
5) And a slab heating process, wherein the heating furnace keeps 15.0Pa micro-positive pressure control, the air-fuel ratio is 1.06, the slab discharging temperature is 1270 ℃, the heating time is 160min, and the temperature of the tail of the slab is increased by 38 ℃ in order to improve the subsequent rolling stability.
6) And (3) controlling a rolling process: wherein the initial rolling temperature of the rough rolling procedure is 1164 ℃, the accumulated reduction rate is controlled between 91 percent, and the final reduction rates of the two passes are respectively 20 percent and 26 percent; in the finish rolling process, the inlet temperature of finish rolling is 1027 ℃, the cumulative reduction rate of finish rolling is controlled according to 73%, the reduction rate of a final stand of the finish rolling is 12%, and the final rolling temperature is 887 ℃.
7) Controlling the cooling and coiling processes: the cooling after rolling adopts ultra-fast cooling and front section intensive cooling, the water temperature is required to be controlled at 20 ℃, the cooling speed is controlled at 150 ℃/s, the strip steel is cooled to 550 ℃ for coiling, and the tension in the coiling process is controlled at 114N/mm 2 。
The specific chemical component content and the performance of the high-performance steel strip for the long-fatigue-life transmission shaft pipe obtained in the embodiment are shown in table 1 and table 2.
Example 7
A preparation method of a high-performance steel strip for a long-fatigue-life transmission shaft tube comprises the working procedures of molten iron pretreatment, converter smelting, refining, slab continuous casting, slab heating, controlled rolling, controlled cooling and reeling. The specific procedures are as follows:
1) the molten iron pretreatment process adopts a magnesium powder and limestone composite blowing process, and the weight ratio of the magnesium powder to the limestone is as follows: 1:4.8.
2) A converter smelting process: the top-bottom combined blowing smelting process is adopted, slag is formed by lime and dolomite, the slag amount of tapping is controlled by a sliding plate slag blocking and infrared slag discharging detection technology during tapping, and the end point P is controlled to be 0.010%.
3) A refining procedure: adopting an LF + RH double refining mode, wherein a deep desulfurization mode is adopted in an LF process for treatment, the S content of an outlet is less than or equal to 0.003 percent, and calcium wires are fed 5min before smelting is finished to perform denaturation treatment on the inclusions; in the RH process, the ultimate vacuum degree is less than or equal to 1.0mbar, the vacuum circulation time is 26min, the net blowing time is 16min, the soft blowing time is prolonged to 10min after the operation is finished, and the operation is kept still for 26 min.
4) And a slab continuous casting process: in the process of pouring molten steel, argon is used for protecting pouring, the degree of superheat of a tundish is 22 ℃, the stable drawing speed is kept in pouring, the drawing speed is controlled to be 1.8m/min, and the fluctuation of the liquid level is controlled to be within +/-3 mm. The secondary cooling water amount of the continuous casting is manually increased by 21 percent on the original basis, the quantity and the size of TiN precipitated are controlled, and the solidification tail end of a casting blank is dynamically and lightly pressed down by 10 mm.
5) And a slab heating process, wherein the heating furnace keeps 12.4Pa micro positive pressure, the air-fuel ratio is 1.18, the tapping temperature of the slab is 1300 ℃, the heating time is 175min, and the tail temperature of the slab is increased by 14 ℃ for improving the subsequent rolling stability.
6) And (3) controlling a rolling process: wherein the initial rolling temperature of the rough rolling procedure is 1178 ℃, the accumulated reduction rate is controlled to be 88 percent, and the final reduction rates of the two passes are respectively 22 percent and 23 percent; in the finish rolling process, the inlet temperature of finish rolling is 1034 ℃, the cumulative reduction rate of finish rolling is controlled according to 68 percent, the reduction rate of a finish rolling final stand is 13 percent, and the finish rolling temperature is 910 ℃.
7) Controlling the cooling and coiling processes: the ultra-fast cooling and front-section intensive cooling are adopted in the cooling after rolling, the water temperature is required to be controlled at 25 ℃, the cooling speed is controlled at 126 ℃/s, the strip steel is cooled to 455 ℃ for coiling, the tension in the coiling process is controlled at 89N/mm 2 。
The specific chemical component content and the performance of the high-performance steel strip for the long-fatigue-life transmission shaft pipe obtained in the embodiment are shown in table 1 and table 2.
Example 8
A preparation method of a high-performance steel strip for a long-fatigue-life transmission shaft tube comprises the working procedures of molten iron pretreatment, converter smelting, refining, slab continuous casting, slab heating, controlled rolling, controlled cooling and reeling. The specific procedures are as follows:
1) the molten iron pretreatment process adopts a magnesium powder and limestone composite blowing process, and the weight ratio of the magnesium powder to the limestone is as follows: 1:5.1.
2) A converter smelting process: the top-bottom combined blowing smelting process is adopted, slag is formed by lime and dolomite, the slag amount of tapping is controlled by a sliding plate slag blocking and infrared slag discharging detection technology during tapping, and the end point P is controlled to be 0.014%.
3) A refining procedure: adopting an LF + RH double refining mode, wherein a deep desulfurization mode is adopted in an LF process for treatment, the S content of the product discharged from the station is 0.004%, and calcium wires are fed 5min before the smelting is finished to perform denaturation treatment on the impurities; in the RH process, the ultimate vacuum degree is less than or equal to 1.0mbar, the vacuum cycle time is 48min, the net blowing time is 20min, the soft blowing time is prolonged to 14min after the product is taken out of the station, and the product is kept stand for 32 min.
4) And a slab continuous casting process: in the process of pouring molten steel, argon is used for protecting pouring, the superheat degree of a tundish is 24 ℃, the pulling speed is kept stable in pouring, the pulling speed is controlled at 2.3/min, and the liquid level fluctuation is controlled within +/-3 mm. The secondary cooling water amount of the continuous casting is manually increased by 20 percent on the original basis, the quantity and the size of TiN precipitated are controlled, and the dynamic soft reduction is carried out on the solidification tail end of a casting blank, wherein the reduction amount is 6 mm.
5) And a slab heating process, wherein the heating furnace maintains 7.9Pa micro positive pressure, the air-fuel ratio is 1.34, the tapping temperature of the slab is 1255 ℃, the heating time is 205min, and the tail temperature of the slab is increased by 32 ℃ for improving the subsequent rolling stability.
6) And (3) controlling a rolling process: wherein the initial rolling temperature of the rough rolling procedure is 1148 ℃, the cumulative reduction rate is controlled between 84 percent, and the final reduction rates of the two passes are respectively 21 percent and 24 percent; in the finish rolling process, the inlet temperature of finish rolling is 1050 ℃, the cumulative reduction rate of finish rolling is controlled according to 71%, the reduction rate of a finish rolling end stand is 9%, and the finishing temperature is 905 ℃.
7) Controlling the cooling and coiling processes: the cooling after rolling adopts ultra-fast cooling and front section intensive cooling, the water temperature is required to be controlled at 29 ℃, the cooling speed is controlled at 86 ℃/s, the strip steel is cooled to 358 ℃ for coiling, and the tension in the coiling process is controlled at 125N/mm 2 。
The specific chemical component content and the performance of the high-performance steel strip for the long-fatigue-life transmission shaft pipe obtained in the embodiment are shown in table 1 and table 2.
The high-performance steel strips for the long-fatigue-life transmission shaft pipes of examples 1 to 8 produced according to the method of the present invention have mechanical properties: the yield strength is 859-951MPa, the tensile strength is 982-1095MPa, the elongation is 23.2-31.0 percent, and the yield ratio is 0.789-0.879. The total content of non-metal impurities is 1.0-2.5 grade, the fatigue cycle life under the working condition of torsion after the transmission tube is manufactured is 169-246 ten thousand times, and the details are shown in Table 2.
Table 1 examples 1-8 control of the chemical composition of the steel strip (unit: wt%)
Figure DEST_PATH_IMAGE002
Table 2 examples 1-8 mechanical properties of steel strips
Figure DEST_PATH_IMAGE004
Although the present invention has been described in detail with reference to the above embodiments, it should be understood by those skilled in the art that: modifications and equivalents may be made thereto without departing from the spirit and scope of the invention and it is intended to cover in the claims the invention as defined in the appended claims.

Claims (9)

1. The preparation method of the high-performance steel strip for the long-fatigue-life transmission shaft pipe is characterized by comprising the working procedures of molten iron pretreatment, converter smelting, refining, slab continuous casting, slab heating, controlled rolling, controlled cooling and reeling; in the refining process, the ultimate vacuum degree in the RH process is less than or equal to 1.0mbar, the vacuum circulation time is 15-50min, the net blowing time is 6-20min, the soft blowing time is prolonged to 10-15min after the refining process is finished, and the refining process is kept still for 10-50 min; the cooling and coiling procedures are controlled, wherein ultrafast cooling and front-section intensive cooling are adopted in the cooling after rolling, the water temperature is controlled to be 20-30 ℃, the cooling speed is controlled to be 40-150 ℃/s, the strip steel is cooled to 350-550 ℃ for coiling, and the tension in the coiling process is controlled to be 80N/mm 2 The above.
2. The preparation method of the high-performance steel strip for the long-fatigue-life transmission shaft tube as claimed in claim 1, wherein the rolling process, the rough rolling process, the initial rolling temperature of 1080-; and a finish rolling procedure, wherein the inlet temperature of finish rolling is 900-.
3. The method for preparing a high-performance steel strip for a long-fatigue-life transmission shaft pipe as claimed in claim 1, wherein the slab continuous casting process is performed in the argon protection casting process, the superheat degree of a tundish is controlled at 10-24 ℃, the casting is kept at a stable casting speed, the casting speed is controlled at 0.9-2.4m/min, and the liquid level fluctuation is controlled within +/-3 mm;
the secondary cooling water amount of the continuous casting is manually increased by 10-25 percent on the original basis, the quantity and the size of TiN precipitated are controlled, and the solidification tail end of a casting blank is dynamically and lightly pressed, wherein the reduction is more than or equal to 4 mm.
4. The method for preparing the high-performance steel strip for the long-fatigue-life transmission shaft pipe according to claim 1, wherein the molten iron pretreatment process adopts a magnesium powder and limestone composite blowing process, and the weight ratio of the magnesium powder to the limestone is as follows: 1: 2.5-5.2.
5. The method for preparing the high-performance steel strip for the long-fatigue-life transmission shaft pipe according to claim 1, wherein the refining process adopts an LF + RH double refining mode, a deep desulfurization mode is adopted in the LF process, S of the outbound molten steel is less than or equal to 0.008 percent, and a calcium wire is fed 5min before smelting to perform modification treatment on the inclusions.
6. The method for preparing a high-performance steel strip for a long-fatigue-life transmission shaft pipe according to any one of claims 1 to 5, wherein the converter smelting process adopts a top-bottom combined blowing smelting process, slag is formed by lime and dolomite, the slag amount of tapping is controlled by a sliding plate slag stopping and infrared slag tapping detection technology during tapping, and the end point P is controlled to be below 0.015%.
7. The method for preparing a high-performance steel strip for a long-fatigue-life transmission shaft tube as claimed in any one of claims 1 to 5, wherein the slab heating process, the heating furnace is kept at a micro-positive pressure of 3-15Pa, the air-fuel ratio is 0.95-1.45, the slab tapping temperature is 1220-.
8. The method for preparing the high-performance steel strip for the long-fatigue-life transmission shaft pipe according to any one of claims 1 to 5, wherein the high-performance steel strip for the transmission shaft pipe comprises the following chemical components in percentage by weight: c: 0.03% -0.10%, Si: 0.03% -0.30%, Mn: 1.60-2.40%, P is less than or equal to 0.020%, S is less than or equal to 0.006%, Als: 0.015% -0.050%, Nb: 0.040% -0.078%, V: 0.040% -0.090%, Ti: 0.030% -0.080%, Cr: 0.15 to 0.55 percent of the total weight of the alloy, less than or equal to 0.0060 percent of N, and the balance of Fe and inevitable residual elements.
9. The method for preparing a high-performance steel strip for a long-fatigue-life transmission shaft tube as claimed in any one of claims 1 to 5, wherein the yield strength of the high-performance steel strip for the transmission shaft tube is not less than 800MPa, the tensile strength is 900-1100MPa, the elongation is not less than 21%, the yield ratio is not more than 0.90, the total content of non-metallic inclusions is not more than 3.0 grade, and the torsional fatigue cycle life of the high-performance steel strip after being made into the transmission shaft tube of the automobile is not less than 150 ten thousand times.
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