CN117127002A - Online flexible heat treatment production line and production process for high-speed wire of high-grade special steel - Google Patents
Online flexible heat treatment production line and production process for high-speed wire of high-grade special steel Download PDFInfo
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- CN117127002A CN117127002A CN202311394342.1A CN202311394342A CN117127002A CN 117127002 A CN117127002 A CN 117127002A CN 202311394342 A CN202311394342 A CN 202311394342A CN 117127002 A CN117127002 A CN 117127002A
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- 238000004519 manufacturing process Methods 0.000 title claims abstract description 78
- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 60
- 239000010959 steel Substances 0.000 title claims abstract description 60
- 238000010438 heat treatment Methods 0.000 title claims abstract description 37
- 238000001816 cooling Methods 0.000 claims abstract description 99
- 150000003839 salts Chemical class 0.000 claims abstract description 87
- 238000005096 rolling process Methods 0.000 claims abstract description 72
- 238000004321 preservation Methods 0.000 claims abstract description 52
- 230000007704 transition Effects 0.000 claims abstract description 13
- 238000000137 annealing Methods 0.000 claims description 17
- 230000009466 transformation Effects 0.000 claims description 16
- 238000009987 spinning Methods 0.000 claims description 15
- 238000011010 flushing procedure Methods 0.000 claims description 12
- 238000004513 sizing Methods 0.000 claims description 10
- 238000009413 insulation Methods 0.000 claims description 8
- 238000012546 transfer Methods 0.000 claims description 8
- 238000010583 slow cooling Methods 0.000 claims description 7
- 229910000997 High-speed steel Inorganic materials 0.000 claims description 2
- 238000007669 thermal treatment Methods 0.000 claims description 2
- 239000002436 steel type Substances 0.000 abstract description 9
- 238000006243 chemical reaction Methods 0.000 abstract description 2
- 238000000034 method Methods 0.000 description 12
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- 229910000639 Spring steel Inorganic materials 0.000 description 4
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Classifications
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/52—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for wires; for strips ; for rods of unlimited length
- C21D9/525—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for wires; for strips ; for rods of unlimited length for wire, for rods
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/26—Methods of annealing
- C21D1/30—Stress-relieving
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/56—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering characterised by the quenching agents
- C21D1/607—Molten salts
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
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Abstract
The invention relates to an online flexible heat treatment production line and production process of high-speed wire rods of high-grade steel, wherein the online flexible heat treatment production line comprises a rolling line, a wire laying machine, an online salt bath line, a stelmor line and an online heat preservation line which are arranged along the production line, a first salt pool section of the online salt bath line is used for rapidly cooling wire rods to a phase transition temperature according to 40-60 ℃/s, a second salt pool section is used for isothermal conversion of the wire rods, the stelmor line is used for cooling the wire rods according to 0.5-20 ℃/s, the online heat preservation line comprises an air cooling roller way, a heat preservation line coil collecting device and at least one heat preservation tunnel which are arranged along the production line and used for slowly cooling according to 0.03-1 ℃/s, the adjustable range of the cooling speed is far greater than that of a conventional stelmor production line, and the online heat treatment of various types of high-grade steel can be achieved by adopting low-temperature heavy load and flexible control according to the determination of the requirements of steel types.
Description
Technical Field
The invention belongs to the technical field of high-speed wire production, and particularly relates to an online flexible heat treatment production line and production process for high-speed wire of high-grade special steel.
Background
As the fields of manufacturing industries such as machinery, automobiles, high-speed trains, aerospace and the like step into a high-quality development stage, the requirements on key parts and components are also higher and higher. The prior high-speed wire heat treatment production line generally adopts a rolling line, a wire laying machine and a Steyr production line which are arranged along the production line, wherein 2 air volumes of 16-20 ten thousand m are correspondingly arranged on each 1 section of conveying roller way on the Steyr production line 3 The fan is used for conveying the wire rods subjected to rolling and wire spinning along a Steyr production line conveying roller way and collecting and discharging the wire rods after being matched with air cooling of the fan, and the main defects are that the cooling speed of the wire rods on the Steyr production line is 0.5-20 ℃/s, the air volume capacity of the fan is limited, particularly the cooling speed of the fan on the unit length in the earlier stage is slower, and only the cooling of steel types such as common high-carbon steel, steel strands with the level below 1860MPa, bridge cable steel with the level below 1860MPa and the like can be carried out.
For large-size wire rods, high carbon content and other wire rods, such as a steel wire rod for bridge cable steel above 2000MPa, a high-strength drawing wire rod for cord steel wire rod above 90 grade and the like, as the finish rolling temperature is generally above 800 ℃, the wire spinning temperature is higher, even if a fan of a Steyr production line is fully opened, isothermal phase transition at a desired temperature is difficult, easy net carbon precipitation occurs, wire rod carbon distribution and tissue uniformity are poor, the sorbite proportion is reduced, the sheet layer spacing is increased, comprehensive mechanical properties are reduced, a pen point is easy to break in the wire rod drawing process, and although the defects can be improved by the cooling speed of the fan in the prior art, the off-line lead bath heat treatment, the on-line water bath and other modes, the off-line salt bath needs to enable coiled and unpacked monofilaments to pass through the salt bath, the efficiency is very low, the problems of difficult stable mass production, large deviation of the same volume, easy abnormal structure and the like exist, the quality stability of the lead bath is easy to generate refractory toxic substances, and the quality stability of the on-line water bath is poor, and the requirement of the on-line production cannot be met.
For steel types such as alloy cold heading steel, alloy welding wire steel, bearing steel, spring steel, tool and die steel and the like, because the finish rolling temperature is higher, the cooling speed of a stelmor production line where the wire rod is positioned in a specific temperature interval is higher, the wire rod cannot be successfully processed in a downstream process, and structural defects and internal stress are easily left in the wire rod, which are unfavorable for the formation of degenerated pearlite, so that the comprehensive mechanical properties have obvious fluctuation, the strength of the wire rod lap joint point is lower, the tensile strength of the wire rod non-lap joint point is higher, or the hardness of the wire rod is increased, if the hardness of the wire rod is too high, brittle fracture occurs in the transportation process, the downstream process cannot be successfully processed, and meanwhile, the downstream production also needs annealing treatment and machining inconvenience, and cannot meet the application requirements.
Disclosure of Invention
The invention aims to solve at least one of the technical problems to a certain extent, and provides an online flexible heat treatment production line and production process for high-speed wire rods of high-grade special steel, which can be suitable for online heat treatment of various types of high-grade special steel based on flexible control, and can obtain wire rod performance remarkably superior to that of conventional air cooling line production.
The technical scheme adopted for solving the technical problems is as follows:
the utility model provides an online flexible thermal treatment production line of high-speed wire rod of high-speed steel of excellent, includes along the pass line, the laying head of production line arrangement, parallelly connected online salt bath line, stelmor line and online heat preservation line, online salt bath line includes along production line interval arrangement's first salt pond section and second salt pond section, first salt pond section is used for the wire rod to drop down to phase transition temperature rapidly, second salt pond section is used for wire rod isothermal transformation, stelmor line is used for wire rod cooling to change, online heat preservation line includes along the forced air cooling roll table, heat preservation line collection rolling device and the at least heat preservation tunnel that is used for the slow cooling of production line arrangement.
Further, the rolling line comprises a heavy-duty finishing mill group and a heavy-duty reducing sizing mill group which are arranged along the production line, wherein the roller diameters of the heavy-duty finishing mill group and the heavy-duty reducing sizing mill group are more than or equal to 250mm and are used for low-temperature heavy-duty rolling at the temperature of less than or equal to 850 ℃.
Further, the online salt bath line, the Steyr line and the online heat preservation line all comprise conveying roller ways arranged along the production line, a turnout is arranged between the online salt bath line and the first conveying roller way of the Steyr line, and a transfer device is arranged between the Steyr line and the first conveying roller way of the online heat preservation line, and between the online salt bath line, the Steyr line and the tail conveying roller way of the online heat preservation line.
Further, a high-pressure flushing device and a salt bath line coil collecting device are arranged at the rear of the second salt pond section at intervals.
Further, the Steyr line is provided with a plurality of first fans and heat preservation covers which are arranged along the conveying roller way, the fans of the first 5 sections of conveying roller ways are densely arranged, and the air quantity of the first fans is more than or equal to 28 ten thousand meters 3 /h。
Further, the heat preservation tunnel is connected with a second fan and an auxiliary heating device.
An online flexible heat treatment production process for a high-speed wire rod of a high-grade special steel, which is based on any one of the online flexible heat treatment production lines, comprises the following steps:
determining the requirements of rapid cooling, air cooling or annealing of the wire rod according to the steel grade, and rolling the blank at low temperature through a rolling line and a wire-laying machine to obtain the wire rod;
for the wire rods needing quick cooling, entering an online salt bath line, quickly cooling to a phase-change temperature in a first salt pond section at a cooling speed of 40-60 ℃/s, and carrying out isothermal transformation in a second salt pond section;
for the wire rods needing air cooling, entering a Steyr wire, and performing cooling transition according to a cooling speed of 0.5-20 ℃/s;
and (3) feeding the wire rods to be annealed into an online heat preservation line, carrying out air cooling through an air cooling roller way, and carrying out stress relief annealing or annealing-free treatment on the wire rods subjected to annealing in a heat preservation tunnel at a cooling speed of 0.03-1 ℃/s after the wire rods are coiled through a heat preservation line coiling device.
Further, the coil rod steel types needing quick cooling comprise GCr15 bearing steel, 40Cr alloy cold heading steel, SCM435 alloy cold heading steel, 55SiCr spring steel, steel for bridge cable steel with the grade of more than 2000MPa and steel for cord wires with the grade of more than 90.
Further, for the wire rod needing quick cooling, the finish rolling temperature and the reducing sizing temperature of the rolling line are 750-800 ℃.
Further, for the wire rods needing quick cooling, the temperature of the wire rods in the first salt pond section is reduced to 730-760 ℃ from 850-950 ℃ after spinning.
Further, for the wire rods needing quick cooling, the wire rods are subjected to isothermal transformation at 500-550 ℃ in the second salt pond section, and after phase transformation is finished, the wire rods are subjected to high-pressure flushing and collected to form coils.
Further, the wire rod steel types needing air cooling comprise conventional cold heading steel, carbon tool steel, PC steel bars, common high-carbon steel, steel strands with the level below 1860MPa and bridge cable steel with the level below 1860 MPa.
Further, for the wire rods requiring air cooling, the finish rolling temperature of the rolling line is 800-850 ℃.
Further, for the wire rods needing air cooling, the wire rods are cooled and converted in a Steyr wire according to a C curve path.
Further, the stress-relief annealed wire rod steel comprises alloy tool steel, spring steel and bearing steel, and the annealing-free wire rod steel comprises alloy cold heading steel and alloy welding wire steel.
Further, for the wire rod to be annealed, the finish rolling temperature of the rolling line is 720-770 ℃.
Further, for the wire rod to be annealed, the wire rod coil collecting temperature is 700-750 ℃.
Further, for the wire rods to be annealed, the wire rods are conveyed in the heat-preserving tunnel at a speed of 0-0.5 m/s.
Compared with the prior art, the invention has the beneficial effects that:
(1) The production line adopts the parallel online salt bath line, the stelmor line and the online heat preservation line, the cooling speed range from 0.03 ℃/s to 60 ℃/s is adjustable and is far greater than the temperature range of the conventional stelmor production line, so that the production process can adopt a corresponding flexible control means, and the method is suitable for online heat treatment of various types of high-quality steel:
the on-line salt bath line can be cooled to the phase transition temperature at extremely high cooling speed through the first salt pond section and the second salt pond section and is subjected to isothermal transformation, the network carbon precipitation interval can be effectively improved, the network carbon distribution is improved, the tissue performance and uniformity are improved, the problems that the existing wire rod is difficult to stably produce in a large scale, the same-circle deviation is large, and abnormal tissue is easy to appear are solved, the nib breakage in the wire rod drawing process is greatly improved, and the on-line salt bath line is suitable for bearing steel, bridge cable steel above 2000MPa level, cord steel above 90 level and the like, for example, the obtained bridge cable steel 87MnSi sorbite rate is more than or equal to 95%, and the same-circle strength deviation is less than or equal to 25MPa;
the stelmor line improves the air quantity of the fans and the front sections are densely arranged, so that the stelmor line is suitable for the production and the manufacture of most conventional steel grades, can obviously refine grains, and can obtain excellent strength and plasticity by conventional cooling control.
The online heat preservation line adopts an air cooling roller way quick-down process, the wire rod is quickly collected after spinning, the heat preservation tunnel can change phase at extremely slow cooling speed, so that the tissue defect and internal stress left in the wire rod are eliminated and improved, the formation of degenerated pearlite during subsequent heat preservation is promoted, the fluctuation of comprehensive mechanical properties is obviously reduced, the strength and hardness of the wire rod are reduced, the stress relief annealing of tool steel, spring steel, bearing steel and other steel types is realized, the relief annealing of alloy cold heading steel, alloy welding wire steel and other steel types is avoided, the downstream annealing process is saved, for example, the strength of the obtained alloy cold heading steel SCM435 with the same coil wire rod is less than or equal to 800MPa, and is superior to 750-1100 MPa of stelmor controlled cooling, and the preparation on tissue and performance is made for the subsequent process.
(2) According to the invention, a low-temperature heavy-load rolling system is formulated according to the requirements of quick cooling, air cooling or annealing, so that the wire rod performance obviously superior to that of the conventional air cooling line can be further obtained by obviously reducing the wire-laying temperature and matching with the flexible control of an online salt bath line, a Steyr line and an online heat preservation line.
Drawings
The foregoing and/or additional aspects and advantages of the invention will become apparent and may be better understood from the following description of embodiments taken in conjunction with the accompanying drawings in which:
FIG. 1 is a schematic structural view of embodiment 1 of the present invention;
FIG. 2 is a schematic diagram of an on-line salt bath line structure according to example 1 of the present invention;
FIG. 3 is a photograph of an organization according to example 2 of the present invention;
FIG. 4 is a photograph of a comparative example 1 tissue;
FIG. 5 is a photograph of an organization of example 3 of the present invention;
FIG. 6 is a photograph of a comparative example 2 tissue.
The marks in the figure: the device comprises a laying head 1, an online salt bath line 2, a first conveying roller way 201, a first salt pond section 202, a second conveying roller way 203, a second salt pond section 204, a third conveying roller way 205, a high-pressure flushing device 206 and a salt bath line coil collecting device 207;
an online heat preservation line 3, an air cooling roller way 301, a heat preservation line coil collecting device 302 and a heat preservation tunnel 303;
the stelmor line 4, the turnout 5 and the transfer device 6.
Detailed Description
Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to like or similar elements or elements having like or similar functions throughout. The embodiments described below by referring to the drawings are illustrative and intended to explain the present invention and should not be construed as limiting the invention.
Example 1:
as shown in fig. 1, a preferred embodiment of the online flexible heat treatment production line for a high-speed wire rod of special steel according to the present invention comprises a rolling line, a laying head 1, an online salt bath line 2, a stelmor line 4 and an online heat preservation line 3 which are connected in parallel along the production line, wherein the online salt bath line 2 comprises a first salt pond section 202 and a second salt pond section 204 which are arranged at intervals along the production line, the first salt pond section 202 is used for rapidly cooling a wire rod to a phase transition temperature, the second salt pond section 204 is used for isothermal conversion of the wire rod, the stelmor line 4 is used for cooling and converting the wire rod, and the online heat preservation line 3 comprises an air cooling roller way 301, a heat preservation line coil collecting device 302 and at least one heat preservation tunnel 303 which are used for slow cooling.
Furthermore, as the deformation resistance of the steel at the temperature below 800 ℃ is obviously increased, the rolling line comprises a heavy-duty finishing mill group and a heavy-duty reducing sizing mill group which are arranged along the production line, the roller diameters of the heavy-duty finishing mill group and the heavy-duty reducing sizing mill group are more than or equal to 250mm and are used for low-temperature heavy-duty rolling at the temperature of less than or equal to 850 ℃, and excellent cold control preparation tissues can be obtained through low-temperature large compression ratio deformation, so that the performance of the wire rod is optimized.
Further, the online salt bath line 2, the stelmor line 4 and the online thermal insulation line 3 all comprise conveying tables arranged along the production line, a turnout 5 is arranged between the online salt bath line 2 and the first conveying table of the stelmor line 4, a transfer device 6 is arranged between the stelmor line 4 and the first conveying table of the online thermal insulation line 3 and between the online salt bath line 2, the stelmor line 4 and the tail conveying table of the online thermal insulation line 3, parallel connection of the online salt bath line 2, the stelmor line 4 and the online thermal insulation line 3 is achieved, wire rods which are threaded by the wire laying machine 1 can enter the conveying tables of the online edge bath line along the turnout 5 or directly enter the first conveying table of the stelmor line 4 and then are transferred to the online thermal insulation line 3 through the first transfer device 6 after entering the first conveying table of the stelmor line 4, and finally coiling the online salt bath line 2, gradually coiling the stelmor line 4, and gradually coiling the online thermal insulation line 3 after final coiling can be packaged by the tail transfer device 6 after gradually coiling.
Further, the transfer device 6 can adopt a roller way structure which is positioned at the intersection of the conveying roller ways and can rotate in the horizontal plane, and different conveying roller ways are abutted after the roller way structure rotates, so that the transfer of the wire rods is realized, and the conveying efficiency of the production line can be further improved.
Further, the high-pressure flushing device 206 and the salt bath line coil collecting device 207 are arranged at intervals behind the second salt pond section 204, as shown in fig. 2, the first conveying roller way 201, the first salt pond section 202, the second conveying roller way 203, the second salt pond section 204, the third conveying roller way 205, the high-pressure flushing device 206 and the salt bath line coil collecting device 207 are sequentially arranged to form the online salt bath line 2, molten salt is arranged in the salt ponds of the first salt pond section 202 and the second salt pond section 204, compared with the existing offline salt bath heat treatment, the online salt bath is directly realized through the molten salt after wire laying, the high-pressure flushing device 206 is used for flushing the salt on the surface of the wire rod after the salt bath through high-pressure water, so that corrosion is avoided, the salt bath line coil collecting device 207 is used for coil collecting and discharging on the online salt bath line 2, further stable mass production is realized, the problems of large same annual and production line yield, abnormal tissue is easy to be produced out, and the yield of the existing yield is increased by 2-3 ten thousand tons to 40-50 ten thousand tons.
Further, the stelmor line 4 is provided with a plurality of first fans and heat insulation covers which are arranged along the conveying roller way, the tail end of the stelmor line 4 is provided with a coil collecting device for coil collecting and coil discharging on the stelmor line 4, the fans of the first 5 sections of conveying roller ways are densely arranged, the length of 1 section of roller way is 9.25 meters, each 1 section of roller way corresponds to 3 first fans and is uniformly arranged, the blowing range of each first fan is about 3.1 meters, the blowing amount is increased, and the blowing amount of the first fans is more than or equal to 28 ten thousand meters 3 And (3) the stronger the air quantity per unit length is, the easier the quick cooling is, the air cooling effect can be obviously improved, and the wire rod is subjected to phase change at a desired temperature, so that the good tissue performance is obtained.
Further, the heat-preserving tunnels 303 are connected with a second fan and an auxiliary heating device, 1-4 heat-preserving tunnels 303 can be arranged, the length of each heat-preserving tunnel 303 is 80m, and a higher temperature environment is formed in each heat-preserving tunnel 303 by using the waste heat of the wire rods and the auxiliary heating device, so that the wire rods are fully and slowly cooled, the release of the residual stress of the wire rods is accelerated, and the purposes of eliminating the stress, improving the tissues and reducing the brittle failure quality are achieved.
Based on any one of the above-mentioned online flexible heat treatment production lines, the online flexible heat treatment production process comprises:
determining the requirements of rapid cooling, air cooling or annealing of the wire rod according to the steel grade, and rolling the blank at low temperature by a rolling line and preparing the blank into the wire rod by a wire laying machine 1;
for the wire rods needing quick cooling, entering an online salt bath line 2, quickly cooling to a phase transition temperature in a first salt pond section 202 at a cooling speed of 40-60 ℃/s, and performing isothermal transformation in a second salt pond section 204 without cooling operation, so that the wire rods are cooled to the phase transition temperature at an extremely quick cooling speed and are subjected to isothermal transformation, thereby effectively improving the network carbon distribution and improving the tissue performance and uniformity;
for the wire rods needing air cooling, entering a Steyr wire 4, and enabling the wire rods to be cooled and converted according to the cooling speed of 0.5-20 ℃/s by adjusting the speed of a conveying roller way, opening a heat preservation cover and a fan, so that the wire rods are suitable for the production and the manufacture of most conventional steel types;
for the wire rods needing annealing, the wire rods enter an online heat preservation line 3, are subjected to air cooling through an air cooling roller way 301 and are collected into coils through a heat preservation line collecting device 302, namely, a quick-down process is adopted, a fan below the air cooling roller way 301 is started, the wire rods are rapidly collected after spinning, the initial temperature of the coils entering a heat preservation tunnel 303 can be controlled, the phase change temperature, the cooling rate and the end temperature are determined according to specific steel type tissues, performance requirements and CCT curves, and then the number of the heat preservation tunnels 303, the conveying roller way speed, auxiliary heating and the fan start are controlled, the heat preservation tunnel 303 is slowly cooled at a cooling rate of 0.03-1 ℃/s, the phase change is carried out at an extremely slow cooling rate, and stress relief annealing or annealing-free treatment is carried out, so that the tissue defects and internal stress left in the wire rods are eliminated and improved, and preparation on tissues and performance is carried out for subsequent procedures.
Further, for the wire rod needing quick cooling, the finish rolling temperature and the reducing sizing temperature of the rolling line are 750-800 ℃, the wire-spinning temperature can be obviously reduced under low-temperature rolling, the time from the wire-spinning temperature to the phase-change temperature is shortened, the phase-change temperature is quickly reached, the net carbide is reduced, and good tissue and final mechanical properties are further obtained.
Further, for the wire rods needing quick cooling, the temperature of the wire rods in the first salt pond section 202 is reduced to 730-760 ℃ from 850-950 ℃ after spinning, the wire rods are rapidly cooled, a net carbon precipitation interval of 800-900 ℃ is avoided, and then the problem of nib breakage in the wire rod drawing process is greatly improved.
Further, for the wire rods needing quick cooling, the wire rods are subjected to isothermal transformation in the second salt pond section 204 at 500-550 ℃, so that the sorbite rate is more than or equal to 95%, the same-circle strength deviation is less than or equal to 25MPa, and the wire rods are subjected to high-pressure flushing and coil collecting to form coils after phase transformation.
Furthermore, as the wire laying temperature is the same as or 10-20 ℃ higher than the finish rolling temperature, for the wire rod needing air cooling, the finish rolling temperature of a rolling line is 800-850 ℃, the wire laying temperature can be obviously reduced under low-temperature rolling, the air cooling difficulty is reduced, the phase change temperature can be reached more quickly under air cooling, further the crystal grains can be obviously thinned, and the excellent plastic-strengthening performance can be obtained through conventional controlled cooling.
Further, for the wire rod needing air cooling, the wire rod is cooled and converted in the Steyr wire 4 according to the C curve path.
Furthermore, for the wire rod needing annealing, the finish rolling temperature of a rolling line is 720-770 ℃, and the low-temperature rolling can promote the formation of degraded pearlite during subsequent heat preservation, reduce the strength and hardness of the wire rod and save the downstream annealing process.
Further, in order to facilitate coil collection, the coil collection temperature of the coil to be annealed is 700-750 ℃.
Further, in order to facilitate slow cooling, the wire rods to be annealed are conveyed in the heat-preserving tunnel 303 at a speed of 0-0.5 m/s.
Example 2:
taking 87MnSi wire rods with the diameter of phi 14mm as an example, based on the online flexible heat treatment production line described in the embodiment 1, a preferred implementation manner of the online flexible heat treatment production process for the high-speed wire rod of the high-grade steel provided by the invention comprises the following steps:
(1) Rolling control: rolling the blank at low temperature through a rolling line: the finishing rolling temperature and the reducing sizing temperature are 770 ℃, and the wire rod is manufactured into a wire rod by a wire laying machine according to the wire laying temperature of 850 ℃ after rolling;
(2) And (3) controlling cooling: and after spinning, the wire rod enters an online salt bath line, the temperature of the wire rod is rapidly reduced to 750 ℃ at the phase transition temperature according to the cooling speed of 40-60 ℃/s in a first salt pond section, the wire rod is subjected to isothermal transformation at 550 ℃ for 10s in a second salt pond section, and the wire rod is subjected to high-pressure flushing through a high-pressure flushing device and is collected and coiled through a salt bath line collecting and coiling device, so that a tissue photograph of the wire rod is shown in figure 3.
Comparative example 1:
an 87MnSi wire rod having a diameter of 14mm was produced in the same manner as in example 1, except that the production process included:
(1) Rolling control: rolling the blank through a rolling line: the finish rolling temperature is 880 ℃, and the rolled wire rod is manufactured into a wire rod by a wire laying machine according to the wire laying temperature of 900 ℃;
(2) And (3) controlling cooling: after spinning, the wire rod enters a Steyr wire, a heat-insulating cover of the Steyr wire is fully opened, a first fan 1-13 is fully opened for 100%, then the coil is collected into a coil, the average cooling speed of the wire rod is 10 ℃/s through field measurement, and a tissue photograph of the obtained wire rod is shown in figure 4.
The 87MnSi wire rods obtained in example 2 and comparative example 1 were tested for mechanical properties according to GB/T2975 standard and for sorbite content according to YB/T169 standard, and the results are shown in Table 1 below:
TABLE 1 comparison of the Properties of two 87MnSi wire rods
As can be seen from the comparison between FIG. 3 and FIG. 4 and the comparison result of Table 1, example 2 adopts a low-temperature rolling and on-line salt bath line, cools to the phase transition temperature at extremely fast cooling speed and carries out isothermal transformation, compared with comparative example 1, the obtained wire rod adopts a Siteur line, the sorbite proportion is higher, the sorbite rate is more than or equal to 95%, the lamellar spacing is finer, the same-circle strength deviation is less than or equal to 25MPa, the net carbon distribution can be effectively improved, and the tissue performance and uniformity are improved, so that the comprehensive mechanical property is better, and the wire rod is suitable for mass production.
Example 3:
taking SCM435 wire rod with diameter of phi 10mm as an example, based on the online flexible heat treatment production line described in example 1, a preferred embodiment of the online flexible heat treatment production process for high-speed wire of high-speed super steel according to the present invention comprises:
(1) Rolling control: rolling the blank at low temperature through a rolling line: the finish rolling temperature is 750 ℃, and the wire rod is manufactured by a wire laying machine according to the wire laying temperature of 830 ℃ after rolling;
(2) And (3) controlling cooling: after spinning, the wire rods enter an online heat preservation line, a 3-section air cooling roller way is used, wherein a number 1 fan to a number 3 fan is respectively started for 40%, the wire rods are collected into coils through a heat preservation line collecting device, the temperature of the wire rods is 700 ℃ to 750 ℃ during collecting, then the wire rods enter a heat preservation tunnel, the conveying roller way speed of the heat preservation tunnel is 0.05m/s, the wire rods are slowly cooled at a cooling speed of 0.03 ℃ to 1 ℃/s, the total furnace time is 1600s, and a tissue photograph of the obtained wire rods is shown in fig. 4.
Comparative example 2:
an SCM435 rod having a diameter of 10mm was produced as in example 3, differing from example 3 in that the production process includes:
(1) Rolling control: rolling the blank through a rolling line: the finish rolling temperature is 880 ℃, and the rolled wire rod is manufactured into a wire rod by a wire laying machine according to the wire laying temperature of 920 ℃;
(2) And (3) controlling cooling: after spinning, the wire rod enters a Steyr wire, the heat-insulating cover of the Steyr wire is completely closed, all fans are completely closed, then the coil is collected into a coil, the average cooling speed of the wire rod is 0.7 ℃/s through field measurement, and the tissue photograph of the obtained wire rod is shown in figure 5.
The SCM435 wire rods obtained in example 3 and comparative example 2 were tested for mechanical properties according to GB/T2975 standard and for metallographic structure according to GB/T15749 standard, and the results are shown in Table 2 below:
TABLE 2 comparison of the Performance of two SCM435 rods
As can be seen from the comparison between FIG. 4 and FIG. 5 and the comparison result of Table 2, the low-temperature rolling and the on-line heat preservation line are adopted in the embodiment 3, the phase transition is carried out at a very slow cooling speed, compared with the comparison example 2, the stelmor line is adopted, the coil rod with low strength, low hardness and high surface shrinkage rate can be stably obtained, the strength of the alloy cold heading steel SCM435 with coil rod is less than or equal to 800MPa, the difference of the same-coil structure is smaller, the problem that the strength of the lap joint point is low and the tensile strength of the non-lap joint point position is more than 850MPa due to the stelmor cooling is avoided, the structure defect and the internal stress left in the coil rod can be eliminated and improved, the brittle failure problem is avoided, and the downstream annealing procedure is saved.
Example 4:
taking an example of producing SWRCH45K wire rods with a diameter of phi 12mm as a specification, based on the online flexible heat treatment production line described in example 1, a preferred implementation manner of the online flexible heat treatment production process for high-speed wire rods of high-grade steel in the invention comprises the following steps:
(1) Rolling control: rolling the blank at low temperature through a rolling line: the finish rolling temperature is 830 ℃, and the rolled wire rod is manufactured into a wire rod by a wire laying machine according to the wire laying temperature of 820 ℃;
(2) And (3) controlling cooling: the wire rod enters a Steyr wire after spinning and passes through the Steyr wire at a roller way speed of 0.3m/s, and the average cooling speed of the wire rod is 2.4 ℃/s until the coil is coiled.
Comparative example 3:
SWRCH45K wire rods having a diameter of 12mm were produced in the same manner as in example 4, except that the production process included:
(1) Rolling control: rolling the blank through a rolling line: the finish rolling temperature is 950 ℃, and the rolled wire rod is manufactured into a wire rod by a wire laying machine according to the wire laying temperature of 920 ℃;
(2) And (3) controlling cooling: the wire rod enters a Steyr wire after spinning and passes through the Steyr wire at a roller speed of 0.3m/s, and the average cooling speed of the wire rod is 2.7 ℃/s until the coil is coiled.
The SWRCH45K wire rods obtained in example 4 and comparative example 3 were tested for mechanical properties according to GB/T2975 standard, metallographic structure according to GB/T15749 standard, and average grain size according to GB6394 standard, and the results are shown in Table 3 below:
TABLE 3 comparison of the Performance of two SWRCH45K wire rods
As can be seen from the comparison results of Table 3, example 4 was able to significantly refine the grains by low temperature rolling and stelmor cooling, and excellent strength and plasticity was obtained by conventional controlled cooling.
In the description of the present invention, it should be understood that the terms "center," "longitudinal," "transverse," "length," "width," "thickness," "upper," "lower," "axial," "radial," "vertical," "horizontal," "inner," "outer," and the like indicate orientations or positional relationships based on the orientation or positional relationships shown in the drawings, merely to facilitate describing the present invention and simplify the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be configured and operated in a specific orientation, and therefore should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more such feature. In the description of the present invention, the meaning of "a plurality" or "a number" means two or more, unless specifically defined otherwise.
In the present invention, unless explicitly specified and limited otherwise, the terms "mounted," "connected," "secured," and the like are to be construed broadly and may be, for example, fixedly connected, detachably connected, or integrally connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art according to the specific circumstances. The above list of detailed descriptions is only specific to practical embodiments of the present invention, and they are not intended to limit the scope of the present invention, and all equivalent embodiments or modifications that do not depart from the spirit of the present invention should be included in the scope of the present invention.
Claims (10)
1. The utility model provides an online flexible thermal treatment production line of high-speed wire rod of high-speed steel, its characterized in that includes along rolling line, the laying head (1) of production line arrangement, parallelly connected online salt bath line (2), stelmor line (4) and online heat preservation line (3), online salt bath line (2) include along production line interval arrangement's first salt pond section (202) and second salt pond section (204), first salt pond section (202) are used for the wire rod to drop down rapidly to the phase transition temperature, second salt pond section (204) are used for the wire rod isothermal transformation, stelmor line (4) are used for the wire rod cooling transformation, online heat preservation line (3) include along air-cooled roll table (301), heat preservation line collection package (302) and at least one heat preservation tunnel (303) that are used for the slow cooling of production line arrangement.
2. The online flexible heat treatment production line for high-speed wires of high-grade steel according to claim 1, wherein the rolling line comprises a heavy-duty finishing mill group and a heavy-duty reducing sizing mill group which are arranged along the production line, and the roller diameters of the heavy-duty finishing mill group and the heavy-duty reducing sizing mill group are more than or equal to 250mm and are used for low-temperature heavy-duty rolling at the temperature of less than or equal to 850 ℃.
3. The online flexible heat treatment production line for high-speed high-grade steel wires according to claim 1, wherein the online salt bath line (2), the stelmor line (4) and the online heat preservation line (3) all comprise conveying tables arranged along the production line, a turnout (5) is arranged between the online salt bath line (2) and a head-end conveying table of the stelmor line (4), and a transfer device (6) is arranged between the stelmor line (4) and the head-end conveying table of the online heat preservation line (3) and between the online salt bath line (2), the stelmor line (4) and a tail-end conveying table of the online heat preservation line (3).
4. The high-speed wire on-line flexible heat treatment production line for high-grade steel according to claim 1, wherein a high-pressure flushing device (206) and a salt bath wire coil collecting device (207) are arranged at intervals behind the second salt pond section (204).
5. The online flexible heat treatment production line for high-speed wire rods of high-grade steel according to claim 1, wherein the Steyr wire rods (4) are provided with a plurality of first fans and heat preservation covers which are arranged along a conveying roller way of the Steyr wire rods, the fans of the first 5-stage conveying roller way are densely arranged, and the air quantity of the first fans is more than or equal to 28 ten thousand meters 3 /h。
6. The high-speed wire on-line flexible heat treatment production line for high-grade special steel according to claim 1, wherein the heat preservation tunnel (303) is connected with a second fan and an auxiliary heating device.
7. An online flexible heat treatment production process for a high-speed wire rod of a high-grade special steel is characterized by comprising the following steps of:
determining the requirements of rapid cooling, air cooling or annealing of the wire rod according to the steel grade, and rolling the blank at low temperature through a rolling line and preparing the blank into the wire rod by a wire laying machine (1);
for the wire rods needing quick cooling, entering an online salt bath line (2), quickly cooling to a phase-change temperature in a first salt pond section (202) at a cooling speed of 40-60 ℃/s, and carrying out isothermal transformation in a second salt pond section (204);
for the wire rods needing air cooling, entering a Steyr wire (4), and performing cooling transition according to a cooling speed of 0.5-20 ℃/s;
and (3) feeding the wire rods to be annealed into an online heat preservation line (3), carrying out air cooling through an air cooling roller way (301), collecting the wire rods by a heat preservation line coil collecting device (302), and carrying out stress relief annealing or annealing-free treatment on the wire rods in a heat preservation tunnel (303) at a cooling speed of 0.03-1 ℃/s.
8. The online flexible heat treatment production process of high-speed wire rods of high-grade special steel according to claim 7, wherein for wire rods needing quick cooling, the finish rolling temperature and the reducing sizing temperature of a rolling line are 750-800 ℃, the temperature of the wire rods in a first salt pond section (202) is reduced to 730-760 ℃ from 850-950 ℃ after wire spinning, the wire rods in a second salt pond section (204) are subjected to isothermal transformation at 500-550 ℃, and after the phase transformation is completed, the wire rods are subjected to high-pressure flushing and coil collecting to form coils.
9. The online flexible heat treatment production process of high-speed wire rods of high-grade steel according to claim 7, wherein the finish rolling temperature of a rolling line is 800-850 ℃ for wire rods needing air cooling, and the wire rods are cooled and converted in a Steyr wire rod (4) according to a C curve path.
10. The online flexible heat treatment production process of high-speed wire rods of high-grade special steel according to claim 7, wherein for wire rods needing annealing, the finish rolling temperature of a rolling line is 720-770 ℃, the wire rod coil collecting temperature is 700-750 ℃, and the wire rods are conveyed in a heat insulation tunnel (303) at a speed of 0-0.5 m/s.
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