CN114134410A - Cord steel wire rod suitable for deep drawing and manufacturing method thereof - Google Patents
Cord steel wire rod suitable for deep drawing and manufacturing method thereof Download PDFInfo
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- CN114134410A CN114134410A CN202111171327.1A CN202111171327A CN114134410A CN 114134410 A CN114134410 A CN 114134410A CN 202111171327 A CN202111171327 A CN 202111171327A CN 114134410 A CN114134410 A CN 114134410A
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- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 57
- 239000010959 steel Substances 0.000 title claims abstract description 57
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 10
- 229910001562 pearlite Inorganic materials 0.000 claims abstract description 31
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 24
- 238000000034 method Methods 0.000 claims abstract description 24
- FBPFZTCFMRRESA-JGWLITMVSA-N D-glucitol Chemical compound OC[C@H](O)[C@@H](O)[C@H](O)[C@H](O)CO FBPFZTCFMRRESA-JGWLITMVSA-N 0.000 claims abstract description 23
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 21
- 230000008859 change Effects 0.000 claims abstract description 19
- 238000005204 segregation Methods 0.000 claims abstract description 17
- 230000008569 process Effects 0.000 claims abstract description 12
- 229910000859 α-Fe Inorganic materials 0.000 claims abstract description 10
- 229910001567 cementite Inorganic materials 0.000 claims abstract description 5
- KSOKAHYVTMZFBJ-UHFFFAOYSA-N iron;methane Chemical compound C.[Fe].[Fe].[Fe] KSOKAHYVTMZFBJ-UHFFFAOYSA-N 0.000 claims abstract description 5
- 238000011156 evaluation Methods 0.000 claims abstract description 4
- 238000001816 cooling Methods 0.000 claims description 26
- 230000009467 reduction Effects 0.000 claims description 15
- 238000009749 continuous casting Methods 0.000 claims description 11
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 11
- 238000004321 preservation Methods 0.000 claims description 10
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N iron oxide Inorganic materials [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 claims description 9
- 230000003647 oxidation Effects 0.000 claims description 9
- 238000007254 oxidation reaction Methods 0.000 claims description 9
- 238000005096 rolling process Methods 0.000 claims description 9
- 238000003723 Smelting Methods 0.000 claims description 8
- SZVJSHCCFOBDDC-UHFFFAOYSA-N ferrosoferric oxide Chemical compound O=[Fe]O[Fe]O[Fe]=O SZVJSHCCFOBDDC-UHFFFAOYSA-N 0.000 claims description 8
- 238000010438 heat treatment Methods 0.000 claims description 8
- 238000009987 spinning Methods 0.000 claims description 8
- 238000005266 casting Methods 0.000 claims description 7
- 238000007711 solidification Methods 0.000 claims description 6
- 230000008023 solidification Effects 0.000 claims description 6
- 229910001566 austenite Inorganic materials 0.000 claims description 5
- 238000006073 displacement reaction Methods 0.000 claims description 4
- 238000007670 refining Methods 0.000 claims description 4
- 229910000677 High-carbon steel Inorganic materials 0.000 claims description 3
- 230000000694 effects Effects 0.000 claims description 3
- 229910052742 iron Inorganic materials 0.000 claims description 3
- 239000000126 substance Substances 0.000 claims description 3
- 239000012535 impurity Substances 0.000 claims description 2
- 230000006911 nucleation Effects 0.000 claims description 2
- 238000010899 nucleation Methods 0.000 claims description 2
- 238000003756 stirring Methods 0.000 claims description 2
- 230000008719 thickening Effects 0.000 claims description 2
- 238000003825 pressing Methods 0.000 claims 3
- 238000009849 vacuum degassing Methods 0.000 claims 1
- 238000010583 slow cooling Methods 0.000 abstract description 6
- 229910000975 Carbon steel Inorganic materials 0.000 abstract 1
- 239000010962 carbon steel Substances 0.000 abstract 1
- 230000009466 transformation Effects 0.000 description 5
- 241000446313 Lamella Species 0.000 description 4
- 238000001556 precipitation Methods 0.000 description 4
- 238000005728 strengthening Methods 0.000 description 4
- 230000000052 comparative effect Effects 0.000 description 3
- 230000006872 improvement Effects 0.000 description 3
- 238000005491 wire drawing Methods 0.000 description 3
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000009792 diffusion process Methods 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 230000007613 environmental effect Effects 0.000 description 2
- 230000002401 inhibitory effect Effects 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 238000012545 processing Methods 0.000 description 2
- 230000002035 prolonged effect Effects 0.000 description 2
- 230000001737 promoting effect Effects 0.000 description 2
- 230000007704 transition Effects 0.000 description 2
- 238000005299 abrasion Methods 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 1
- 230000003466 anti-cipated effect Effects 0.000 description 1
- 229910001563 bainite Inorganic materials 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 229910052729 chemical element Inorganic materials 0.000 description 1
- 229910052681 coesite Inorganic materials 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 229910052593 corundum Inorganic materials 0.000 description 1
- 229910052906 cristobalite Inorganic materials 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000000227 grinding Methods 0.000 description 1
- 229910000734 martensite Inorganic materials 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000005272 metallurgy Methods 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 235000012239 silicon dioxide Nutrition 0.000 description 1
- 238000002791 soaking Methods 0.000 description 1
- 239000006104 solid solution Substances 0.000 description 1
- 229910052682 stishovite Inorganic materials 0.000 description 1
- 238000004781 supercooling Methods 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 229910052905 tridymite Inorganic materials 0.000 description 1
- 229910001845 yogo sapphire Inorganic materials 0.000 description 1
Images
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
-
- 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
-
- 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
- B21B1/02—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 heavy work, e.g. ingots, slabs, blooms, or billets, in which the cross-sectional form is unimportant ; Rolling combined with forging or pressing
- B21B1/04—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 heavy work, e.g. ingots, slabs, blooms, or billets, in which the cross-sectional form is unimportant ; Rolling combined with forging or pressing in a continuous process
-
- 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
- B21B1/16—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 wire rods, bars, merchant bars, rounds wire or material of like small cross-section
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D22/00—Shaping without cutting, by stamping, spinning, or deep-drawing
- B21D22/20—Deep-drawing
-
- 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
- B22D11/005—Continuous casting of metals, i.e. casting in indefinite lengths of wire
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
- B60C9/00—Reinforcements or ply arrangement of pneumatic tyres
- B60C9/0007—Reinforcements made of metallic elements, e.g. cords, yarns, filaments or fibres made from metal
-
- 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
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0247—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment
-
- 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
- C21D8/06—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of rods or wires
- C21D8/065—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of rods or wires of ferrous alloys
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C33/00—Making ferrous alloys
- C22C33/04—Making ferrous alloys by melting
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
-
- 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
- B21B1/02—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 heavy work, e.g. ingots, slabs, blooms, or billets, in which the cross-sectional form is unimportant ; Rolling combined with forging or pressing
- B21B2001/022—Blooms or billets
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/005—Ferrite
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/009—Pearlite
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- Materials Engineering (AREA)
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- Metallurgy (AREA)
- Crystallography & Structural Chemistry (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Manufacturing & Machinery (AREA)
- Heat Treatment Of Steel (AREA)
- Metal Rolling (AREA)
- Continuous Casting (AREA)
- Treatment Of Steel In Its Molten State (AREA)
- Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)
- Carbon Steel Or Casting Steel Manufacturing (AREA)
- Heat Treatment Of Strip Materials And Filament Materials (AREA)
Abstract
The invention relates to a cord steel wire rod suitable for deep drawing and a manufacturing method thereof, wherein the metallographic structure of the wire rod is sorbite + pearlite + ferrite, the sorbite proportion is controlled to be 60-70%, the pearlite proportion is 30-40%, the ferrite is a small-amount structure, and the proportion is less than or equal to 10%. The thickness of the pearlite layer is 0.10-0.35 mm, the size of the pearlite colony is 10-20 um, and the pearlite characteristics correspond to smaller dislocation density. The central carbon segregation grade is evaluated according to YB/T4413 & lthigh carbon steel wire rod central carbon segregation metallographic evaluation method & gt, is less than or equal to 1 grade, and the grade of the network cementite in the structure is less than or equal to 1 grade. The cold control method, particularly the slow cooling in the cold control process, performs phase change and then is slowly cooled by covering, so that the sorbite tissue content and the pearlite sheet layer distance can be obviously changed, the tensile strength sigma of the wire rod is controlled to be (103762 Ceq-114606 Ceq) MPa, the surface shrinkage is more than 38%, and the wire rod is more suitable for deep drawing.
Description
Technical Field
The invention belongs to the technical field of metallurgy, and particularly relates to a cord steel wire rod and a manufacturing method thereof.
Background
The rapid development of automobile lightweight and the rapid rise of new energy automobiles enable the strength requirement of the steel cord for the automobile tire skeleton to be gradually improved. The strength grades of the steel cords are also gradually developed from the initial common strength (NT) grade common strength to the present ultra high Strength (ST) grade ultra high strength and ultra high strength (UT) grade ultra high strength grades.
The higher the strength of the steel wire, the smaller the diameter after drawing and the more complicated the structure, so for the wire rod for cord steel, inclusions mainly MnS and deformable 40% SiO in steel are reasonably controlled2+15％Al2O3The + 20% CaO composite inclusion and other deformable inclusions contribute to the improvement of the drawing performance of the wire rod. In addition, the ratio of the sorbite structure in the wire rod structure also affects the drawing performance of the wire rod, generally, the wire rod is subjected to isothermal transformation in the temperature range of being cooled to 600-650 ℃, the transformation structure is sorbite, for high-carbon steel wire rods, the sorbite ratio is generally more than 85%, the sorbite is too high, the pearlite lamella is fine, the tensile strength of the wire rod is too high, the dislocation density is large, the drawing hardening is increased, and the deep drawing is not facilitated; the sorbite proportion is too low, the wire rod has low strength, poor plasticity and poor drawing deformation capability, and is not suitable for deep drawing. Therefore, the requirement of low wire breakage rate in deep drawing of the wire rod can be met only by controlling the proportion of sorbite and the tensile strength in the wire rod in a proper range, and the steel cord is further pushed to high strengthThe development of transformation and refinement is proceeding.
By solving the technical problems, the popularization of the production of UT-grade steel cords and wire rods for cutting steel wires with the pressure of more than 4000MPa can be realized.
Disclosure of Invention
The object of the present invention is to provide a wire rod of cord steel suitable for deep drawing intended to reduce the proportion of sorbite in the wire rod structure. The metallographic structure of the wire rod is composed of sorbite, pearlite and ferrite, wherein the sorbite proportion is controlled to be 60-70%, the pearlite proportion is 30-40%, and the ferrite is a small-amount structure and is less than or equal to 10%. The ratio of the structures in the wire rod refers to the area ratio of the structures in a metallographic structure diagram (e.g., an SEM magnified view) of the wire rod.
Further, this application is anticipated to obtain the pearlite structure that the lamella is thicker, and pearlite lamella thickness is at 0.10 ~ 0.35mm, and pearlite group size 10 ~ 20um reduces the dislocation density of metallographic structure to avoid tensile strength too big, restrain the drawing hardening.
Further, the method is intended to control the central carbon segregation level of the wire rod in advance, and according to the evaluation of YB/T4413 metallographic evaluation method of central carbon segregation of high-carbon steel wire rods, the central carbon segregation level of the wire rod is less than or equal to 1 level, so that the precipitation of reticular cementite in the cooling process of the wire rod can be effectively inhibited, and the level of the reticular cementite in the structure is less than or equal to 1 level, which is 0 level.
Further, the thickness of the oxide skin on the surface of the wire rod is 13-18um, which is 5um greater than the thickness of the existing average oxide layer, and FeO/Fe in the oxide skin3O4＝2～2.5：1，FeO/Fe3O4Lower, more easily achieve ideal (mechanical) descaling effect and contribute to obviously reducing the wire breakage rate of wire rod drawing.
The tensile strength sigma of the wire rod is (103762-114606-Ceq) MPa, the carbon equivalent Ceq is C + Mn/6+ Cr/5, the element symbol in the formula represents the weight percentage content of the element in the steel, the strength is moderate, the wire rod is more suitable for deep drawing, and the wire breakage rate is obviously reduced. The tensile strength of the wire rod produced in the prior art ranges from σ (120387 × Ceq to 131231 × Ceq) MPa, and is mainly determined by two factors: one is the chemical composition, i.e., carbon equivalent; the cooling intensity and the phase transition temperature of the wire rod during cooling are small, the phase transition temperature is high, and the wire rod intensity is low; the cooling intensity is large, the phase change temperature is low, and the wire rod intensity is high. The application mainly prevents the tensile strength from being too high by controlling the cooling strength.
The wire rod comprises the following chemical components in percentage by mass: c: 0.70-0.99%, Si: 0.15-0.30%, Mn: 0.15-0.60%, Cr: 0.01-0.50%, and the balance of Fe and inevitable impurity elements. Strength relates to 72, 82, 86, 92 cord steel.
The action principle of chemical elements in the wire rod of the application is as follows:
c is a main strengthening element in the high-carbon hard wire steel, the strength of the steel is improved through solid solution strengthening and precipitation strengthening, the strength of the wire rod is improved along with the increase of the carbon content, and the strength of the drawn steel wire is also improved along with the improvement of the strength. However, the probability of the precipitation of the net cementite at the core of the wire rod is increased along with the increase of the carbon content in the hypereutectoid steel. Therefore, the C content of the present invention is set in the range of 0.78 to 0.99%.
Si is a main deoxidizing element in the cord steel, and SiO2 inclusions which are harmless are generated through Si deoxidization. However, Si is also an element for strengthening ferrite, and too high Si content in the cord steel causes the ferrite phase plasticity in pearlite to be reduced and the wire drawing ductility to be deteriorated, so that the Si content in the present invention is controlled to 0.15 to 0.30%.
Mn can be deoxidized in the cord steel to form deformable MnS inclusions, and is an element which is mainly used for improving the strength in the steel. However, Mn is also an easily segregating element, too high Mn causes segregation of the steel material to be increased, hardenability of the steel is increased, supercooling degree during austenite cooling is increased, pearlite lamellae are thinned, strength is improved, and plasticity is deteriorated. Therefore, the Mn content of the invention is controlled to be 0.15-0.60%.
Cr can promote the C curve to move right and down in the cord steel, postpone the sorbite phase-change time, reduce the phase-change temperature, can refine the pearlite lamellar spacing, can obviously improve the plasticity index of steel, obviously improve the drawing processing performance, realize large drawing deformation, reduce intermediate heat treatment and improve the final strength of the drawn steel wire. However, when the content of Cr in the cord steel is too high, bainite and martensite in a supercooled structure are easily formed in the cooling process, the plastic deformation is poor, and the drawing processing performance of the steel is influenced, and Cr is preferably controlled to be less than 0.35 percent in the invention.
The application also provides a manufacturing method of the cord steel wire rod, which comprises the following specific production process flows: the method comprises the steps of KR molten iron pretreatment, converter smelting, LF refining, square billet continuous casting, square billet heating and rolling and wire rod cooling which are sequentially carried out.
Wherein:
smelting molten steel conforming to component design, continuously casting the molten steel into small square billets by adopting a continuous casting process, controlling the superheat degree of a tundish at 15-30 ℃, and arranging an electromagnetic stirring device, wherein a dynamic soft reduction device is adopted at a solidification tail end, and a displacement reduction mode is adopted for pressure rollers in each area of a withdrawal and straightening machine, wherein the displacement reduction amounts of rollers 1# -6# are respectively 2mm,2mm,3mm,4mm,4mm and 4 mm. Compared with the conventional continuous casting billet carbon segregation control method mainly adopting a soft reduction technology, the dynamic reduction method adopts a 'soft reduction + hard reduction' combined reduction technology, soft reduction is adopted at the initial solidification stage of the casting billet, and hard reduction is adopted at the later solidification stage. And the continuous casting billet carbon segregation index is less than or equal to 1.05, wherein the continuous casting billet carbon segregation index is equal to the continuous casting billet core C%/smelting C%.
The blank rolling selects proper heating temperature, specifically, the temperature of a high-temperature section in a heating furnace before rolling is more than 1180 ℃, the total heating time is more than 120min, and the high-temperature time is more than 60min, so that the enough temperature and time diffusion of the casting blank are ensured. The core carbon segregation is further suppressed by high temperature diffusion.
The final rolling temperature of the wire rod is controlled to be 800-.
And (3) controlling the cooling of the coil of the wire rod after spinning on an air cooling roller way, wherein the speed range of the roller way is 0.95-1.05m/s, and the coil of the wire rod is gradually increased from 0.95 m/s. Starting a No. 1-3 fan to accelerate the initial cooling rate of the wire rod, promoting the wire rod to be rapidly cooled to below 700 ℃ from the spinning temperature, promoting the refinement of the size of a pearlite colony, and inhibiting the precipitation of net carbon, wherein a small amount of ferrite is precipitated at the stage; the cooling speed in the fast cooling stage is controlled at 15-20 ℃/s, the air volume opening degree of the fan is adjusted according to the environment temperature, specifically, the environment temperature is more than 20 ℃, and the opening degree of the 1-3# fan is divided intoRespectively 90%, 90% and 70%. The specific environmental temperature is below 20 ℃, and the 1-3# fan opening degrees are respectively 90%, 90% and 50%. And all the subsequent fans (the rest fans behind the No. 3 fan) are closed, the closing is mainly fully and slowly cooled, the wire rod enters a phase change region, the transformation from austenite to sorbite and pearlite is realized, the sorbite phase change temperature is improved, the sorbite phase change at about 650 ℃ is realized, the phase change time is prolonged, and the isothermal transformation is realized. The release of phase change latent heat in the phase change process can enable the temperature of the wire rod to rise again along with the completion of the phase change and then fall again, the phase change is basically finished after the temperature of the wire rod falls below 570 ℃, then a heat preservation cover is arranged on the wire rod coil for slow cooling, the thickening of an oxidation layer on the surface of the wire rod is promoted, and FeO in the oxidation layer is further converted into Fe3O4Reduction of FeO/Fe3O4。
The heat preservation cover on the air cooling roller way is arranged: the 1-11# heat preservation cover corresponds to the fast cooling and phase change interval, the heat preservation cover is not arranged on the air cooling roller way corresponding to the two cooling intervals, the heat preservation covers after 12# are all closed, the wire rod is guaranteed to be fully heat preserved at about 570 ℃, the wire rod is fully slowly cooled, the thickness of an oxide layer is increased, the components of the oxide layer are adjusted, the descaling of the wire rod is facilitated, and the wire drawing breakage rate is reduced.
Compared with the prior art, the invention has the advantages that:
(1) the wire rod produced by the invention has coarse pearlite lamella and small pearlite colony size, can adapt to deep drawing of the wire rod, reduces the crack generation tendency of a steel wire under the condition of large area reduction rate drawing, and effectively reduces the wire breakage rate by 30 percent compared with the normal process.
(2) C in the wire rod: 0.70-0.99 percent of high-carbon coil rod steel, and the sorbite proportion of the high-carbon coil rod steel is more than 85 percent generally, the sorbite proportion of the coil rod in the coil rod manufacturing method, particularly the controlled cooling process in the method, is controlled to be 60-70 percent, and the proportion of coarse lamellar pearlite is 30-40 percent. The tensile strength of the wire rod is effectively reduced through the coarsening sheet layer, on one hand, the abrasion of a grinding tool and the surface heating of the steel wire can be reduced in the rough drawing stage, and the risk of surface defects is reduced, so that the drawing wire breakage rate is reduced. On the other hand, in the case of deep drawing, pearlite lamellae are too fine, so that the true strain of the steel wire when the surface shrinkage is reduced in the drawing process is reduced, that is, the drawing reduction amount that the steel wire can maintain stable plasticity to bear is reduced, that is, the deep drawability of the steel wire is reduced.
(3) The thickness of the oxidation layer of the wire rod produced by the invention is 13-18um which is 5um thicker than that of the oxidation layer produced by the normal process, and the oxidation layer is FeO/Fe3O4The wire rod descaling device is (2-2.5)/1, and is more beneficial to mechanical descaling of a wire rod, and the drawing loss of the wire rod on the surface due to incomplete descaling of the wire rod is reduced, so that the wire drawing breakage rate of the steel wire is influenced.
Drawings
FIG. 1 is a microstructure of a wire rod according to example 1 of the present invention;
fig. 2 is a schematic diagram of an oxide layer of a wire rod according to embodiment 2 of the present invention.
Detailed Description
The present invention will be described in further detail with reference to specific examples.
Taking the example of smelting 100 tons of molten steel to manufacture the cord steel wire rod, the casting blank of each embodiment with the following components is produced by adopting the flow of molten iron pretreatment, converter smelting, LF refining and continuous casting to form a square blank, and the carbon segregation index of the continuous casting blank meets less than or equal to 1.05.
And (3) putting the continuous casting square billet into a furnace for heating, ensuring that the soaking temperature is higher than 1180 ℃, keeping the high temperature time of higher than 1180 ℃ for more than 4 hours, ensuring that the casting billet is fully heated and diffused, and further reducing the carbon segregation. Continuously rolling the continuous casting square billet into a wire rod in an austenite phase region, controlling the final rolling temperature of the wire rod at 900 ℃ plus 800 ℃, setting the rolling speed at 95-120 m/s, controlling the spinning temperature at 950 ℃ plus 900 ℃, improving the spinning temperature and increasing the austenite stability, and cooling a wire rod coil after spinning by adopting fast cooling, slow cooling and heat preservation. The speed of the roller way where the coil of the wire rod is located is set to be 0.95m/s, and the speed of the roller way is gradually increased to 1.05m/s so as to pull the coil distance apart. Starting a No. 1-3 fan to realize quick cooling, accelerating pearlite nucleation and inhibiting pearlite growth, wherein the opening degree of the fan is 90%, 90% and 30%; the fan after 3# is closed to carry out slow cooling, the wire rod enters a phase change interval, the wire rod is subjected to phase change under the conditions of environmental temperature and self latent heat release, the phase change temperature is increased to about 650 ℃, the Soxhlet phase change time is prolonged, and the wire rod is identified after the temperature of the wire rod is reduced and is reduced to below 570 DEG CFor finishing the phase change, the heat preservation cover correspondingly closes the 12# post heat preservation cover at the moment to preserve heat of the wire rod after the phase change, and promotes the FeO layer on the surface part of the wire rod to be converted into Fe3O4The setting can be generally the thickness of FeO/Fe on the surface of the wire rod3O4The thickness is adjusted to (2-2.5)/1, the wire rod descaling effect is better, and the surface defects and the wire breakage rate during drawing are reduced.
Examples 1 to 5 refer to table 1 for the elemental composition of the wire rod and the ingot segregation index.
TABLE 1
See table 2 for specific process parameters for examples 1-5 and two comparative examples.
TABLE 2
The test properties of the final wire rods of examples 1-5 and the two comparative examples are shown in table 3.
TABLE 3
By comparison of the above examples and comparative examples, it can be demonstrated that: by adopting the cooling control method, particularly the slow cooling in the cooling control process for phase change and the subsequent covering and slow cooling, the sorbite tissue content and the pearlite sheet layer distance can be obviously changed, so that the tensile strength of the wire rod is controlled, the requirement that the tensile strength sigma is (103762 Ceq-114606 Ceq) MPa is met, and the drawing performance is improved.
Although preferred embodiments of the present invention have been described in detail hereinabove, it should be clearly understood that modifications and variations of the present invention are possible to those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (13)
1. A cord steel wire rod adapted for deep drawing characterized by: the metallographic structure of the wire rod is composed of sorbite, pearlite and ferrite, wherein the sorbite proportion is controlled to be 60-70%, the pearlite proportion is 30-40%, and the ferrite is a small-amount structure and is less than or equal to 10%.
2. A cord steel wire rod adapted for deep drawing according to claim 1, characterized in that: the thickness of the pearlite layer is 0.10-0.35 mm, the size of the pearlite colony is 10-20 um, and the pearlite characteristics correspond to smaller dislocation density.
3. A cord steel wire rod adapted for deep drawing according to claim 1, characterized in that: the central carbon segregation grade of the wire rod is evaluated according to YB/T4413 < high carbon steel wire rod central carbon segregation metallographic evaluation method > and is less than or equal to grade 1, and the grade of the network cementite in the structure is less than or equal to grade 1.
4. A cord steel wire rod adapted for deep drawing according to claim 1, characterized in that: the tensile strength sigma of the wire rod is (103762 Ceq-114606 Ceq) MPa, wherein the carbon equivalent Ceq is C + Mn/6+ Cr/5, and the symbol of the element in the formula represents the weight percentage of the element in the wire rod.
5. A cord steel wire rod adapted for deep drawing according to claim 1, characterized in that: the thickness of the oxidation layer on the surface of the wire rod is 13-18um, and FeO/Fe in the oxidation layer3O42-2.5: 1, has better descaling effect.
6. A cord steel wire rod adapted for deep drawing according to claim 1, characterized in that: the surface shrinkage of the wire rod is more than or equal to 38 percent.
7. A cord steel wire rod adapted for deep drawing according to claim 1, characterized in that: the wire rod comprises the following chemical components in percentage by mass: c: 0.70-0.99%, Si: 0.15-0.30%, Mn: 0.15-0.60%, Cr: 0.01-0.50%, and the balance of Fe and inevitable impurity elements.
8. A cord steel wire rod adapted for deep drawing according to claim 7, wherein: the wire rod strength relates to 72-grade, 82-grade, 86-grade, 92-grade cord steel.
9. A method of manufacturing a cord steel wire rod suitable for deep drawing, characterized by: casting the smelted molten steel into a square billet, wherein the carbon segregation index of the square billet is less than or equal to 1.05, and the carbon segregation index is equal to the core C% of the square billet per smelting C%;
heating the square billet, wherein the temperature of a high-temperature section is higher than 1180 ℃, the holding time of the high-temperature section is longer than 60min, then rolling the square billet into continuous wire rods, wherein the finish rolling temperature is 800-900 ℃, and the spinning temperature is 850-950 ℃;
and (3) carrying out controlled cooling on the wire rod coil subjected to spinning on an air cooling roller way: starting a fan to rapidly cool the wire rod from the spinning temperature to below 700 ℃ at a cooling speed of 15-20 ℃/s, wherein a small amount of ferrite is generated in the stage, and the pearlite nucleation quantity is promoted; then the wire rod enters a phase change region, the fan is closed, and the wire rod is transformed from austenite to sorbite and pearlite at room temperature; when the temperature of the wire rod is reduced to below 570 ℃, a heat preservation cover is arranged for the wire rod coil, the wire rod which is converted by the sorbite is fully and slowly cooled in the heat preservation cover, the thickening of an oxidation layer is promoted, and FeO in the oxidation layer is further converted into Fe3O4。
10. The method of claim 9, wherein: the smelting of the molten steel relates to KR molten iron pretreatment, converter smelting and LF refining, and the molten steel is directly cast into a square billet without vacuum degassing after the LF refining.
11. The method of claim 9, wherein: the method is characterized in that the molten steel is cast into a square billet by adopting a continuous casting process, the superheat degree of a tundish is controlled at 15-30 ℃, an electromagnetic stirring device is arranged, a dynamic soft reduction device is adopted at the solidification tail end, soft reduction is adopted at the early solidification stage of a casting billet, and heavy reduction is adopted at the later solidification stage.
12. The method of claim 11, wherein: the dynamic soft pressing equipment refers to that the pressure rollers in all areas of the withdrawal and straightening machine adopt a displacement pressing mode, wherein the displacement pressing amounts of the 1# to 6# pressure rollers are respectively 2mm,2mm,3mm,4mm,4mm and 4 mm.
13. The method of claim 9, wherein: the speed of the air-cooled roller way is 0.95-1.05m/s, and the speed is gradually increased from 0.95m/s, so that the distance between the wire rod coils is gradually increased.
Priority Applications (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111171327.1A CN114134410A (en) | 2021-10-08 | 2021-10-08 | Cord steel wire rod suitable for deep drawing and manufacturing method thereof |
| PCT/CN2021/123778 WO2023056658A1 (en) | 2021-10-08 | 2021-10-14 | Cord steel wire rod suitable for deep drawing and manufacturing method therefor |
| KR1020237009103A KR20230051564A (en) | 2021-10-08 | 2021-10-14 | Cord threaded steel wire rod suitable for deep drawing and manufacturing method thereof |
| JP2023537249A JP2023554466A (en) | 2021-10-08 | 2021-10-14 | Cord steel wire suitable for deep drawing and its manufacturing method |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202111171327.1A CN114134410A (en) | 2021-10-08 | 2021-10-08 | Cord steel wire rod suitable for deep drawing and manufacturing method thereof |
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| CN114134410A true CN114134410A (en) | 2022-03-04 |
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| CN202111171327.1A Pending CN114134410A (en) | 2021-10-08 | 2021-10-08 | Cord steel wire rod suitable for deep drawing and manufacturing method thereof |
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| Country | Link |
|---|---|
| JP (1) | JP2023554466A (en) |
| KR (1) | KR20230051564A (en) |
| CN (1) | CN114134410A (en) |
| WO (1) | WO2023056658A1 (en) |
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| CN118497633A (en) * | 2024-07-19 | 2024-08-16 | 江苏永钢集团有限公司 | 12.9-Grade non-quenched and tempered hot-rolled high-carbon cold heading steel wire rod and manufacturing method thereof |
| CN118621230A (en) * | 2024-08-14 | 2024-09-10 | 江苏永钢集团有限公司 | 14.9-Grade annealing-free hot-rolled high-carbon cold heading steel wire rod and manufacturing method thereof |
| CN118621220A (en) * | 2024-08-14 | 2024-09-10 | 江苏永钢集团有限公司 | Cold heading steel high-carbon wire rod for 14.9-grade bolt and manufacturing method thereof |
| CN118639124A (en) * | 2024-08-19 | 2024-09-13 | 江苏永钢集团有限公司 | Cold heading steel high-carbon hot-rolled wire rod for 15.9-grade bolt and manufacturing method thereof |
| CN118639122A (en) * | 2024-08-16 | 2024-09-13 | 江苏永钢集团有限公司 | 15.9-Grade annealing-free hot-rolled high-carbon cold heading steel wire rod and manufacturing method thereof |
| CN118639124B (en) * | 2024-08-19 | 2024-11-19 | 江苏永钢集团有限公司 | Cold heading steel high-carbon hot-rolled wire rod for 15.9-grade bolt and manufacturing method thereof |
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| CN118497633A (en) * | 2024-07-19 | 2024-08-16 | 江苏永钢集团有限公司 | 12.9-Grade non-quenched and tempered hot-rolled high-carbon cold heading steel wire rod and manufacturing method thereof |
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Also Published As
| Publication number | Publication date |
|---|---|
| KR20230051564A (en) | 2023-04-18 |
| WO2023056658A1 (en) | 2023-04-13 |
| JP2023554466A (en) | 2023-12-27 |
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