CN113073259A - Cold heading steel wire rod for annealing-free 10.9-grade fastener and manufacturing method thereof - Google Patents
Cold heading steel wire rod for annealing-free 10.9-grade fastener and manufacturing method thereof Download PDFInfo
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- CN113073259A CN113073259A CN202110270159.5A CN202110270159A CN113073259A CN 113073259 A CN113073259 A CN 113073259A CN 202110270159 A CN202110270159 A CN 202110270159A CN 113073259 A CN113073259 A CN 113073259A
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- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 80
- 239000010959 steel Substances 0.000 title claims abstract description 80
- 239000000789 fastener Substances 0.000 title claims abstract description 36
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 22
- 238000000034 method Methods 0.000 claims abstract description 36
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 33
- 238000001816 cooling Methods 0.000 claims abstract description 27
- 238000007670 refining Methods 0.000 claims abstract description 21
- 238000005096 rolling process Methods 0.000 claims abstract description 18
- 238000009749 continuous casting Methods 0.000 claims abstract description 16
- 239000000126 substance Substances 0.000 claims abstract description 15
- 229910052782 aluminium Inorganic materials 0.000 claims abstract description 11
- 238000003723 Smelting Methods 0.000 claims abstract description 9
- 229910052804 chromium Inorganic materials 0.000 claims abstract description 8
- 229910052802 copper Inorganic materials 0.000 claims abstract description 5
- 229910052759 nickel Inorganic materials 0.000 claims abstract description 5
- OKTJSMMVPCPJKN-UHFFFAOYSA-N carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 22
- XKRFYHLGVUSROY-UHFFFAOYSA-N argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims description 14
- 238000003756 stirring Methods 0.000 claims description 10
- 238000010079 rubber tapping Methods 0.000 claims description 9
- 229910052786 argon Inorganic materials 0.000 claims description 7
- 230000001965 increased Effects 0.000 claims description 7
- 239000002893 slag Substances 0.000 claims description 7
- 229910045601 alloy Inorganic materials 0.000 claims description 6
- 239000000956 alloy Substances 0.000 claims description 6
- REDXJYDRNCIFBQ-UHFFFAOYSA-N aluminium(3+) Chemical class [Al+3] REDXJYDRNCIFBQ-UHFFFAOYSA-N 0.000 claims description 6
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminum Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 6
- 238000007664 blowing Methods 0.000 claims description 6
- 239000003795 chemical substances by application Substances 0.000 claims description 4
- OYPRJOBELJOOCE-UHFFFAOYSA-N calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 claims description 3
- 229910052791 calcium Inorganic materials 0.000 claims description 3
- 239000011575 calcium Substances 0.000 claims description 3
- 238000006477 desulfuration reaction Methods 0.000 claims description 3
- 230000003009 desulfurizing Effects 0.000 claims description 3
- 239000002245 particle Substances 0.000 claims description 3
- 230000001681 protective Effects 0.000 claims description 3
- 238000005728 strengthening Methods 0.000 claims description 3
- 238000000137 annealing Methods 0.000 abstract description 8
- 229910052748 manganese Inorganic materials 0.000 abstract description 7
- 238000009847 ladle furnace Methods 0.000 description 11
- 238000010791 quenching Methods 0.000 description 9
- 230000000171 quenching Effects 0.000 description 9
- 238000010273 cold forging Methods 0.000 description 7
- 230000000052 comparative effect Effects 0.000 description 7
- 239000002994 raw material Substances 0.000 description 6
- 238000005496 tempering Methods 0.000 description 6
- 238000010438 heat treatment Methods 0.000 description 5
- 238000009740 moulding (composite fabrication) Methods 0.000 description 5
- 238000009628 steelmaking Methods 0.000 description 5
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 4
- 229910001339 C alloy Inorganic materials 0.000 description 3
- 229910000746 Structural steel Inorganic materials 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 229910052758 niobium Inorganic materials 0.000 description 3
- 239000010955 niobium Substances 0.000 description 3
- 238000009987 spinning Methods 0.000 description 3
- 229910052720 vanadium Inorganic materials 0.000 description 3
- 229910000975 Carbon steel Inorganic materials 0.000 description 2
- 229910000805 Pig iron Inorganic materials 0.000 description 2
- 239000010962 carbon steel Substances 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 238000005098 hot rolling Methods 0.000 description 2
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- 238000011068 load Methods 0.000 description 2
- 229910000499 pig iron Inorganic materials 0.000 description 2
- 238000004321 preservation Methods 0.000 description 2
- 229910000712 Boron steel Inorganic materials 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 238000007792 addition Methods 0.000 description 1
- 238000005275 alloying Methods 0.000 description 1
- 229910052796 boron Inorganic materials 0.000 description 1
- -1 carbon boron Chemical compound 0.000 description 1
- 238000010622 cold drawing Methods 0.000 description 1
- 238000000641 cold extrusion Methods 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 239000000498 cooling water Substances 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 230000002708 enhancing Effects 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 229910052750 molybdenum Inorganic materials 0.000 description 1
- GUCVJGMIXFAOAE-UHFFFAOYSA-N niobium Chemical compound [Nb] GUCVJGMIXFAOAE-UHFFFAOYSA-N 0.000 description 1
- 238000005482 strain hardening Methods 0.000 description 1
- LEONUFNNVUYDNQ-UHFFFAOYSA-N vanadium(0) Chemical compound [V] LEONUFNNVUYDNQ-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- 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
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21C—MANUFACTURE OF METAL SHEETS, WIRE, RODS, TUBES OR PROFILES, OTHERWISE THAN BY ROLLING; AUXILIARY OPERATIONS USED IN CONNECTION WITH METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL
- B21C37/00—Manufacture of metal sheets, bars, wire, tubes or like semi-manufactured products, not otherwise provided for; Manufacture of tubes of special shape
- B21C37/04—Manufacture of metal sheets, bars, wire, tubes or like semi-manufactured products, not otherwise provided for; Manufacture of tubes of special shape of bars or wire
- B21C37/047—Manufacture of metal sheets, bars, wire, tubes or like semi-manufactured products, not otherwise provided for; Manufacture of tubes of special shape of bars or wire of fine wires
-
- 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
- C22C33/06—Making ferrous alloys by melting using master alloys
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/42—Ferrous alloys, e.g. steel alloys containing chromium with nickel with copper
Abstract
The invention belongs to the technical field of cold heading steel, and particularly relates to a cold heading steel wire rod for an annealing-free 10.9-grade fastener and a manufacturing method thereof. The main chemical component range of the cold heading steel wire rod for the annealing-free 10.9-grade fastener is C: 0.25 to 0.29%, Si: less than or equal to 0.10 percent, Mn: 0.95-1.15%, Cr: 0.40-0.50%, Al: 0.020-0.050%, P, S is less than or equal to 0.025%, and Ni and Cu are less than or equal to 0.20%. The manufacturing method comprises a converter smelting process, an LF refining process, an RH vacuum refining process, a square billet continuous casting process and a wire rod rolling process. By optimizing the design of the element components such as C, Mn, Cr and the like and combining the rolling and cooling control scheme, the hot rolled wire rod obtains higher cold heading performance, the C content is more than or equal to 0.25 percent, and B is not added, so that the requirement of foreign users on producing special 10.9-grade high-strength fasteners without annealing is met.
Description
Technical Field
The invention belongs to the technical field of cold heading steel, and relates to a cold heading steel wire rod for an annealing-free 10.9-grade fastener, and a manufacturing method of the cold heading steel wire rod for the annealing-free 10.9-grade fastener.
Background
Cold heading steel is also called cold heading forming steel, and cold heading is formed by adopting one-time or multiple-time impact loading at room temperature, is used for producing fasteners such as screws, pins, nuts and the like, and is widely used in the industries such as automobiles, shipbuilding, equipment manufacturing, electronics, household appliances, bicycles, tools, light steel structures, buildings and the like. The cold heading process can save raw materials and reduce cost, and the tensile strength of a workpiece is improved and the performance is improved through cold work hardening, the steel for cold heading must have good cold heading performance, the surface quality requirement of steel is strict, high-quality carbon steel is often adopted, if the carbon steel content of the steel is more than 0.25%, spheroidizing annealing heat treatment is carried out to improve the cold heading performance of the steel. At present, steel grades of cold heading steel wire rods widely applied in China can be classified into four types, namely low-carbon high-quality carbon structural steel, medium-carbon high-quality carbon structural steel, low-carbon alloy structural steel and medium-carbon alloy steel according to strength grades. In the cold heading steel industry, cold heading steel with the C content of less than 0.25% is generally changed into low-carbon cold heading steel, and cold heading steel with the C content of 0.25-0.48% is changed into medium-carbon cold heading steel.
High-strength cold heading steel is generally used for producing bolt products above grade 8.8 or nut products above grade 8, and high-strength fasteners gradually become mainstream in the industry along with the development of the fastener industry and industries such as downstream automobiles, high-speed rails, aviation, wind power, engineering machinery and the like. Fasteners with different strength levels need to adopt different cold heading steel grades and adopt different processing technologies. Generally, fasteners below 6.8 grade are mostly made of non-heat treatment type medium carbon and low carbon cold heading steel, and finished fasteners do not need quenching and tempering treatment; the steel for 10.9-grade high-strength fasteners usually adopts medium carbon alloy steel or medium carbon boron steel, and the mechanical properties of the steel can meet the requirements through quenching and tempering heat treatment.
Currently, most domestic steel mills provide four series of medium carbon Cr-Mo cold heading steels (representative brands comprise ML35CrMo, SCM435, SCM440, 35CrMo, 42CrMo and the like), medium carbon Cr cold heading steels (representative brands comprise ML40Cr, 40Cr and the like), medium carbon B cold heading steels (representative brands comprise 10B33, 10B30 and the like) and low carbon B cold heading steels so as to meet the production requirements of downstream users for 10.9 fasteners.
In the field of cold heading steel, C is the most important element influencing the cold heading forming capability of a hot rolled wire rod, and the higher the carbon content is, the higher the strength of the steel is, and the lower the plasticity is. Practice proves that the yield strength sigma s is improved by 27.4MPa when the carbon content is improved by 0.1 percent; the tensile strength sigma b is improved by 58.8-78.4 MPa. It can be seen that the carbon content in the steel has a great influence on the cold heading formability of the hot rolled wire rod. In practical production, for cold heading steel with cold heading and cold extrusion deformation degrees as high as 65% -80%, when the carbon content is more than 0.25%, the wire rod is required to be subjected to spheroidizing annealing before cold heading forming.
In the prior art, although cold forging steel with low carbon content can be used for producing various fasteners of 10.9 grade, the requirement of export cold forging steel with special requirement on carbon content is difficult to meet due to low carbon content. The cold forging steel adopting niobium and vanadium composite micro-alloying can reach the requirement of 10.9 grade, but in the steel components, alloy with expensive Nb and V is also needed to be added, and users cannot accept the alloy due to overhigh price. The medium carbon cold heading steel with the carbon content of more than 0.25% has a scheme of spheroidizing-free annealing, but the hot rolling plasticity is insufficient, so that the medium carbon cold heading steel can only be used for producing fasteners such as 10.9-grade outer hexagon bolts, hexagon nuts and the like at present, the production of flange fasteners cannot be met, and the cold heading cracking rate in the production process of downstream users can be increased. And it is often necessary to add B element, such as CN110453150A, a Cr-B series low carbon high strength cold heading steel wire rod and a method for manufacturing the same, since B can significantly improve hardenability of steel. In addition, the outlet cold heading steel with special requirements on components requires that element B cannot be added, and once the element B is not allowed to be added, the product difficulty is increased, so that the requirements for producing 10.9-grade fasteners cannot be met by many existing technologies. And in order to meet the climate requirements of other countries, such as the lower temperature in the winter in north america, the fastener is also required to satisfy the excellent low temperature impact resistance.
Therefore, the development of the cold heading steel wire rod which has relatively high C content, does not add B element, does not contain noble elements such as Nb and V, has excellent hot rolling cold heading performance, meets the requirements of foreign users on producing 10.9-grade high-strength fasteners without annealing (the C content is more than or equal to 0.25 percent and B is not added), and meets the policy requirements of tax refunds of steel enterprises in China is a problem to be solved urgently at present.
Disclosure of Invention
In order to solve the problems, the invention optimizes the design of the element components such as C, Mn, Cr and the like, combines the rolling and cooling control scheme, ensures that the hot rolled wire rod obtains higher cold heading performance, meets the requirements of special 10.9-grade high-strength fasteners for the annealing-free production of the cold heading steel wire rod (the content of C is more than or equal to 0.25 percent, B is not added), meets the policy requirements of tax refund of domestic steel enterprises and exports, and enhances the competitiveness of domestic steel enterprises and exports.
A manufacturing method of an outlet type annealing-free cold heading steel wire rod for a 10.9-grade fastener is characterized by comprising the steps of chemical composition design, converter smelting, LF refining, RH vacuum refining, square billet continuous casting and wire rod rolling. The method for manufacturing the wire rod of the present invention will be described in detail below.
Designing chemical components:
the wire rod comprises the following chemical components in percentage by weight: 0.25 to 0.29%, Si: less than or equal to 0.10 percent, Mn: 0.95-1.15%, Cr: 0.40-0.50%, Al: 0.020-0.050%, P, S is less than or equal to 0.025%, and Ni and Cu are less than or equal to 0.20%.
Compared with medium-carbon Cr-Mo cold forging steel, the chemical components of the wire rod of the invention do not use Mo element, thereby reducing Cr content and C content and improving Mn content; compared with medium-carbon Cr cold forging steel, the Cr content and the C content are reduced, and the Mn content is increased; compared with medium carbon B cold forging steel, the use of B element is cancelled, the C content is reduced, and the Cr content is increased; compared with low-carbon B cold forging steel, the use of B element is cancelled, the C content is increased, and the Cr content is reduced;
in conclusion, the wire rod provided by the invention cancels two traditional alloy elements of Mo and B for improving the quenching performance, maintains a certain amount of Cr element, and simultaneously matches reasonable contents of C and Mn, so that the hardenability and hardenability of steel are ensured by the components, and the mechanical performance of the fastener after quenching and tempering meets the basic condition of 10.9 grade. Meanwhile, the component design meets the requirements of special requirements of producing 10.9-grade high-strength fasteners by using outlet cold heading steel wire rods (the chemical component requirements of the fasteners are that the content of C is more than or equal to 0.25 percent, B is not added), and meets the policy requirements of export tax refunds of steel enterprises in China (Cr is more than or equal to 0.30 percent). In addition, the chemical components of the invention are more beneficial to obtaining uniform and stable microstructure of the hot rolled wire rod, so as to obtain excellent cold heading forming performance, and provide an important basis for realizing the production of 10.9-grade high-strength fasteners without annealing.
A converter smelting process:
manufacturing high-alkalinity slag (alkalinity R: 6-9) in a converter smelting process, ensuring sufficient slag amount and full submerged arc, and carrying out bottom argon blowing and stirring in the whole process, wherein the steel tapping temperature is more than or equal to 1580 ℃, the steel tapping carbon is controlled within the range of 0.08-0.12%, and the steel tapping P, S is less than or equal to 0.010%; adding a deoxidizer, an alloy, a carburant and slag charge into the steel discharge 1/4 in sequence; the amounts and types of addition are conventionally adjusted according to the steel composition.
An LF refining procedure:
in the early stage of the LF refining process, aluminum particles are adopted for strengthening deoxidation and desulfurization, and an aluminum wire is used for adjusting the Al content in place at one time; adjusting all elements to target components 10 minutes before LF (ladle furnace) is taken out of the station, wherein the LF refining is performed in the whole process by adopting weak stirring operation, the flow of stirring gas for weak stirring is 50-100L/min, and the stirring gas is argon.
RH vacuum refining process:
the RH vacuum refining adopts high vacuum degree and ensures sufficient time, wherein the high vacuum degree is required to be less than 65Pa, and the time is required to be more than or equal to 25 min. Feeding pure calcium wires with the weight of 50-80 m/furnace (120 tons per furnace) through a wire feeder after the RH is broken empty, wherein the soft blowing time is more than or equal to 20 min.
A square billet continuous casting process:
controlling the continuous casting superheat degree of the square billet continuous casting procedure at 20-30 ℃, executing slow-speed constant-drawing-speed control, and adopting a weak-cooling scheme with the specific water amount of 0.30-0.40L/kg for secondary cooling, wherein the drawing speed is 2.1-2.5 m/min; in the continuous casting process, an alkaline covering agent is adopted, argon protection is performed between a ladle nozzle and a long nozzle, and micro-positive pressure of 0.8-0.9 Pa is kept.
A wire rod rolling procedure:
the finishing mill set controls rolling at 800-840 ℃, the finishing rolling temperature of the wire rod is 860-880 ℃, and spinning is carried out at 820-840 ℃ after rolling. After rolling, cooling to be less than or equal to 550 ℃ through a stelmor cooling control line at a cooling speed of 0.6-0.8 ℃/s, then leaving the cooling control line, entering a PF line for normal circulation, increasing protective outer packages when cooling to be less than or equal to 100 ℃, and bundling by using a bundling machine.
The cold heading steel hot-rolled wire rod meets the requirements of special requirements of export cold heading steel wire rods for producing 10.9-grade high-strength fasteners (the content of C is more than or equal to 0.25 percent, B is not added), and meets the policy requirements of export tax refunds of domestic steel enterprises (the content of Cr is more than or equal to 0.30 percent), and the export tax refunds can be obtained by the wire rod exported from domestic steel enterprises. The hot-rolled cold-heading steel wire rod rolled by the invention is subjected to cold drawing, cold-heading forming, quenching and tempering heat treatment to produce various fasteners of 10.9 grades such as flange bolts, flange nuts, inner hexagon bolts and the like, and annealing treatment is not required before cold heading, so that the processing cost of downstream users is reduced.
Detailed Description
The invention comprises the following steps: the specific components of the cold heading steel wire rod HS-10 (phi 20.0mm) for the outlet type annealing-free 10.9-grade fastener are as follows:
Wt，％
| C | Si | Mn | P | S | Cr | Ni、Cu | Al |
| 0.25-0.29 | ≤0.10 | 0.95-1.15 | ≤0.025 | ≤0.025 | 0.40-0.50 | ≤0.20 | 0.020-0.050 |
the manufacturing process of the wire rod comprises the following steps: converter smelting process, LF refining process, RH vacuum refining process, square billet continuous casting process and wire rod rolling.
Example 1
1. Composition design
The chemical components are designed as follows by weight percent: 0.25%, Si: 0.05%, Mn: 0.99%, Cr: 0.44%, Al: 0.037%, P: 0.012%, S: 0.011%, Ni: 0.02%, Cu: 0.09 percent.
2. Smelting in a converter
Adding steel-making raw materials (the steel-making raw materials comprise molten iron, pig iron and scrap steel, wherein the pig iron accounts for 93% of the total weight of the steel-making raw materials, the scrap steel accounts for 7% of the total weight of the steel-making raw materials, and the total loading amount of the steel-making raw materials is 125 t/furnace) into a converter, carrying out bottom argon blowing stirring in the whole smelting process of the converter, controlling the tapping temperature to be 1590 ℃, controlling the tapping C to be 0.09-0.11%, and controlling the tapping P, S to be less than or; and (3) adding a deoxidizer, an alloy, a carburant and slag charge into the steel discharge 1/4 in sequence.
3. LF refining
In the early stage of the LF refining process, aluminum particles are adopted for strengthening deoxidation and desulfurization, and an aluminum wire is used for adjusting the Al content in place at one time; adjusting all elements to target components 10 minutes before LF is outbound, and then immediately outbound, wherein the LF refining is operated by weak stirring in the whole process.
4. RH vacuum refining
RH vacuum refining adopts high vacuum degree, and ensures sufficient time, wherein the high vacuum degree is required to be less than 65Pa, and the time is 30 min. Feeding a proper amount of pure calcium wires through a wire feeding machine after the RH is broken, and carrying out soft blowing for 25 min.
5. Continuous casting of square billets
The continuous casting process of the billet comprises covering with a covering agent, the continuous casting comprises an integral stopper, the using time of the tundish is 8 hours, the diameter of a water gap is 35mm, the using time of the water gap is 6.5 hours, and the superheat degree of the continuous casting is controlled at 27 ℃. Executing constant pulling speed control of pulling speed of 1.70 m/min; the crystallizer adopts electromagnetic stirring, wherein the current is 240 +/-10A, and the frequency is 3 +/-0.2 Hz; the secondary cooling adopts a weak cooling water distribution mode, and the specific water amount is 0.45L/kg; and an alkaline covering agent is adopted in the continuous casting process, so that the argon protection between a ladle nozzle and a long nozzle is enhanced, and the actual positive pressure is 0.8-0.9 Pa.
6. Wire rod rolling
The wire rod is rolled by adopting a high-speed wire rod production line, and is spun into a ring by a spinning machine after being rolled, and enters a stelmor controlled cooling line for controlled cooling. The actual low-temperature controlled rolling temperature of the wire rod finishing mill set is 805-832 ℃, the actual spinning temperature is 821-835 ℃, and the cooling scheme is controlled after rolling to be cooled to 496-520 ℃ at the cooling speed of 0.65-0.76 ℃/s and leave the controlled cooling line. And (4) after the wire rod is collected and coiled, the wire rod enters a PF line to normally flow, is cooled to 70-98 ℃, is additionally provided with a protective outer package, and is bundled by using a bundling machine.
Example 2
The chemical components in step 1 of example 1 are replaced by the chemical components in percentage by weight, and the design is C: 0.29%, Si: 0.09%, Mn: 1.14%, Cr: 0.49%, Al: 0.030%, P: 0.010%, S: 0.013%, Ni: 0.06%, Cu: 0.10%, and the other conditions were the same as in example 1.
Comparative example 1
The chemical components in the step 1 of the embodiment 1 are replaced by C in percentage by weight: 0.33%, and the other conditions were the same as in example 1.
Comparative example 2
The chemical components in the step 1 of the embodiment 1 are replaced by Mn in percentage by weight: 0.60%, and the other conditions were the same as in example 1.
Comparative example 3
The chemical components in the step 1 of the embodiment 1 are replaced by Mn in percentage by weight: 1.50%, and the other conditions were the same as in example 1.
Comparative example 4
The chemical components in the step 1 of the embodiment 1 are replaced by Cr: 0.80%, and the other conditions were the same as in example 1.
Comparative example 5
The cooling scheme controlled in the step 6 of the embodiment 1 is replaced by the way that the heat-preserving cover is completely opened, the temperature is cooled to be less than or equal to 550 ℃ at the cooling speed of 2.0 ℃/s, and other conditions are the same as the embodiment 1.
Comparative example 6
The cooling scheme controlled in the step 6 of the embodiment 1 is replaced by starting a fan for air cooling, the temperature is cooled to be less than or equal to 550 ℃ at the cooling speed of 10 ℃/s, and other conditions are the same as the embodiment 1.
The hot-rolled cold upsetting performance and the performance after heat treatment (quenching temperature 870 +/-10 ℃, quenching heat preservation time 40min, quenching medium quenching oil, tempering temperature 450 +/-10 ℃ and tempering heat preservation time 30min) of the wire rods in the embodiment of the invention are compared with those in the comparative example in the following table 1:
TABLE 1
Remarking: 1. the cold upsetting performance of the hot rolled 1/4 coil rod is qualified, and the 10.9-grade high-strength fastener can be produced without annealing.
The 2.10.9-level high-strength fastener requires that the tensile strength is more than or equal to 1000MPa, the yield strength is more than or equal to 900MPa, and the yield ratio is more than or equal to 0.8.
3. -30 ℃ impact absorption energy KU based on user feedback2 cWhen the/J value is larger than or equal to 78, the low-temperature impact resistance of the bolt meets the requirement.
Claims (4)
1. The utility model provides an exempt from to anneal 10.9 level cold-heading steel wire rod for fastener which characterized in that: the cold heading steel wire rod comprises the following chemical components: according to weight percentage, C: 0.25 to 0.29%, Si: less than or equal to 0.10 percent, Mn: 0.95-1.15%, Cr: 0.40-0.50%, Al: 0.020-0.050%, P, S is less than or equal to 0.025%, and Ni and Cu are less than or equal to 0.20%.
2. A manufacturing method of a cold heading steel wire rod for an annealing-free 10.9-grade fastener is characterized by comprising the following steps of: comprises a converter smelting process, an LF refining process, an RH vacuum refining process, a square billet continuous casting process and a wire rod rolling process;
manufacturing high-alkalinity slag in a converter smelting process, ensuring sufficient slag amount, carrying out bottom argon blowing stirring in the whole process, controlling the tapping temperature to be more than or equal to 1580 ℃, controlling the tapping carbon to be within the range of 0.08-0.12%, and simultaneously controlling the tapping P, S to be less than or equal to 0.010%; adding a deoxidizer, an alloy, a carburant and slag charge into the steel discharge 1/4 in sequence;
in the early stage of the LF refining process, aluminum particles are adopted for strengthening deoxidation and desulfurization, and an aluminum wire is used for adjusting the Al content in place at one time; adjusting all elements to target components 10 minutes before LF is out of the station, and carrying out LF refining by adopting weak stirring operation in the whole process;
RH vacuum refining process, adopting high vacuum degree and ensuring sufficient time, wherein the high vacuum degree is required to be less than 65Pa, the time is required to be more than or equal to 25min, feeding a proper amount of pure calcium wires through a wire feeder after RH vacuum breaking, and the soft blowing time is more than or equal to 20 min;
controlling the continuous casting superheat degree of a square billet continuous casting procedure at 20-30 ℃, executing slow-speed constant-pulling speed control, and adopting a weak cooling scheme for secondary cooling; in the continuous casting process, an alkaline covering agent is adopted, argon protection is performed between a ladle nozzle and a long nozzle, and micro-positive pressure of 0.8-0.9 Pa is kept;
the wire rod finishing mill set controls rolling at 800-840 ℃, the final rolling temperature of the wire rod is less than or equal to 880 ℃, and wire is spun at 820-840 ℃ after rolling.
3. The method for manufacturing the cold heading steel wire rod for the annealing-free 10.9-grade fastener according to claim 2, wherein the method comprises the following steps: after rolling, cooling to be less than or equal to 550 ℃ through a stelmor cooling control line at a cooling speed of 0.6-0.8 ℃/s, then leaving the cooling control line, entering a PF line for normal circulation, increasing protective outer packages when cooling to be less than or equal to 100 ℃, and bundling by using a bundling machine.
4. Use of a cold-headed steel wire rod for an anneal-free 10.9 grade fastener according to any of claims 1-3 in the production of a 10.9 grade bolt.
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| CN114990437A (en) * | 2022-05-25 | 2022-09-02 | 张家港荣盛特钢有限公司 | Cold heading steel wire rod and production method thereof |
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