CN116083806A - Cold heading steel hot rolled wire rod for delayed fracture resistant 14.9-grade quenched and tempered bolt and preparation method thereof - Google Patents
Cold heading steel hot rolled wire rod for delayed fracture resistant 14.9-grade quenched and tempered bolt and preparation method thereof Download PDFInfo
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- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 55
- 239000010959 steel Substances 0.000 title claims abstract description 55
- 230000003111 delayed effect Effects 0.000 title claims abstract description 26
- 238000002360 preparation method Methods 0.000 title claims abstract description 10
- 238000005096 rolling process Methods 0.000 claims abstract description 64
- 238000000034 method Methods 0.000 claims abstract description 61
- 238000009749 continuous casting Methods 0.000 claims abstract description 51
- 238000003723 Smelting Methods 0.000 claims abstract description 33
- 238000004519 manufacturing process Methods 0.000 claims abstract description 30
- 238000000227 grinding Methods 0.000 claims abstract description 28
- 238000007670 refining Methods 0.000 claims abstract description 21
- 238000001514 detection method Methods 0.000 claims abstract description 13
- 238000001816 cooling Methods 0.000 claims description 46
- 238000010583 slow cooling Methods 0.000 claims description 37
- 238000010438 heat treatment Methods 0.000 claims description 23
- 239000000126 substance Substances 0.000 claims description 23
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims description 20
- 238000010079 rubber tapping Methods 0.000 claims description 20
- 229910052799 carbon Inorganic materials 0.000 claims description 16
- 238000005098 hot rolling Methods 0.000 claims description 15
- 238000004321 preservation Methods 0.000 claims description 15
- 239000002893 slag Substances 0.000 claims description 13
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 10
- 229910045601 alloy Inorganic materials 0.000 claims description 10
- 239000000956 alloy Substances 0.000 claims description 10
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 10
- 229910052782 aluminium Inorganic materials 0.000 claims description 10
- 229910052786 argon Inorganic materials 0.000 claims description 10
- 238000007664 blowing Methods 0.000 claims description 10
- 229910000616 Ferromanganese Inorganic materials 0.000 claims description 9
- DALUDRGQOYMVLD-UHFFFAOYSA-N iron manganese Chemical compound [Mn].[Fe] DALUDRGQOYMVLD-UHFFFAOYSA-N 0.000 claims description 9
- 239000003795 chemical substances by application Substances 0.000 claims description 8
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 7
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 6
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 claims description 5
- MBMLMWLHJBBADN-UHFFFAOYSA-N Ferrous sulfide Chemical compound [Fe]=S MBMLMWLHJBBADN-UHFFFAOYSA-N 0.000 claims description 5
- 229910000677 High-carbon steel Inorganic materials 0.000 claims description 5
- ZDVYABSQRRRIOJ-UHFFFAOYSA-N boron;iron Chemical compound [Fe]#B ZDVYABSQRRRIOJ-UHFFFAOYSA-N 0.000 claims description 5
- 239000011575 calcium Substances 0.000 claims description 5
- 229910052791 calcium Inorganic materials 0.000 claims description 5
- 238000004868 gas analysis Methods 0.000 claims description 5
- 229910052742 iron Inorganic materials 0.000 claims description 5
- 239000006247 magnetic powder Substances 0.000 claims description 5
- 239000002245 particle Substances 0.000 claims description 5
- 238000005070 sampling Methods 0.000 claims description 5
- 238000004513 sizing Methods 0.000 claims description 5
- 238000003756 stirring Methods 0.000 claims description 5
- 230000001502 supplementing effect Effects 0.000 claims description 5
- 239000000463 material Substances 0.000 abstract description 4
- 238000010791 quenching Methods 0.000 description 10
- 230000000171 quenching effect Effects 0.000 description 10
- 238000005496 tempering Methods 0.000 description 10
- 230000000052 comparative effect Effects 0.000 description 9
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 7
- 229910052739 hydrogen Inorganic materials 0.000 description 7
- 239000001257 hydrogen Substances 0.000 description 7
- 239000000203 mixture Substances 0.000 description 7
- 239000002994 raw material Substances 0.000 description 7
- 238000000137 annealing Methods 0.000 description 5
- 238000007127 saponification reaction Methods 0.000 description 5
- 229910000914 Mn alloy Inorganic materials 0.000 description 4
- 229910052804 chromium Inorganic materials 0.000 description 4
- PYLLWONICXJARP-UHFFFAOYSA-N manganese silicon Chemical compound [Si].[Mn] PYLLWONICXJARP-UHFFFAOYSA-N 0.000 description 4
- 229910052698 phosphorus Inorganic materials 0.000 description 4
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 description 4
- 229910010271 silicon carbide Inorganic materials 0.000 description 4
- 229910052720 vanadium Inorganic materials 0.000 description 4
- 235000008733 Citrus aurantifolia Nutrition 0.000 description 3
- 235000011941 Tilia x europaea Nutrition 0.000 description 3
- 239000002253 acid Substances 0.000 description 3
- 229910052796 boron Inorganic materials 0.000 description 3
- 239000004571 lime Substances 0.000 description 3
- 238000002844 melting Methods 0.000 description 3
- 230000008018 melting Effects 0.000 description 3
- 238000009987 spinning Methods 0.000 description 3
- 229910052717 sulfur Inorganic materials 0.000 description 3
- 238000004381 surface treatment Methods 0.000 description 3
- 238000005406 washing Methods 0.000 description 3
- 238000005336 cracking Methods 0.000 description 2
- 238000006356 dehydrogenation reaction Methods 0.000 description 2
- 229910052750 molybdenum Inorganic materials 0.000 description 2
- 239000003921 oil Substances 0.000 description 2
- 238000005457 optimization Methods 0.000 description 2
- 238000005554 pickling Methods 0.000 description 2
- 229910000599 Cr alloy Inorganic materials 0.000 description 1
- 229910000954 Medium-carbon steel Inorganic materials 0.000 description 1
- 229910001182 Mo alloy Inorganic materials 0.000 description 1
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 239000003344 environmental pollutant Substances 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 230000002427 irreversible effect Effects 0.000 description 1
- 239000011572 manganese Substances 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 239000011574 phosphorus Substances 0.000 description 1
- 231100000719 pollutant Toxicity 0.000 description 1
- 239000013585 weight reducing agent Substances 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
-
- 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
-
- 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
-
- 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
-
- 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
- C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
-
- 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
- C22C38/54—Ferrous alloys, e.g. steel alloys containing chromium with nickel with boron
-
- 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
- Y02P10/20—Recycling
Abstract
The invention belongs to the technical field of cold heading steel, and particularly relates to a cold heading steel hot rolled wire rod for a delayed fracture resistant 14.9-grade quenched and tempered bolt and a preparation method thereof. The cold heading steel hot rolled wire rod comprises the following components in percentage by weight: c:0.58 to 0.64 percent, si:0.35 to 0.45 percent, mn:1.70 to 1.90 percent, P: less than or equal to 0.010 percent, S:0.025 to 0.035 percent, al:0.020 to 0.040 percent, B: 0.0025-0.0035%, cr, ni, cu, mo% or less than 0.10%. The method is prepared by adopting the working procedures of converter smelting, LF refining, RH vacuum refining, billet continuous casting, cogging rolling, flaw detection of rolled billets, grinding of rolled billets and wire rod rolling. The plasticity, strength and hardenability of the material are effectively improved, the problem of delayed fracture of the bolt is solved, and the production requirement of the delayed fracture resistant 14.9-grade quenched and tempered bolt in downstream industry production is met.
Description
Technical Field
The invention belongs to the technical field of cold heading steel, relates to a cold heading steel hot-rolled wire rod for a delay fracture-resistant 14.9-grade quenched and tempered bolt, and further relates to a preparation method of the cold heading steel hot-rolled wire rod for the delay fracture-resistant 14.9-grade quenched and tempered bolt.
Background
With rapid development of industries such as aviation, automobiles, high-speed rails, ships, wind power, military industry, steel structures, bridges and the like, the requirements of driving high-strength fasteners are increased, and further increase of the strength level of the fasteners is promoted. Taking the automotive industry as an example, as a first large consumer field of fastener products, the number and variety of fasteners required by the automotive industry are numerous. Along with the increase of industry energy saving and emission reduction pressure, automobile light weight becomes an important direction of industry development, and the adoption of a high-strength fastener can reduce weight and increase installation space by reducing self size under the same clamping force, so that functions and volume optimization can be performed on connected parts, and the aim of overall weight reduction and performance optimization of equipment is achieved, so that the fastener is required to have higher strength.
The high-strength fasteners which are industrially produced in mass production in the domestic industry at present comprise four grades of 8.8 grade, 9.8 grade, 10.9 grade and 12.9 grade, and the fasteners with higher strength which are developed comprise 13.9 grade, 14.9 grade and the like, but most of the fasteners have not yet been industrially produced in mass production. With the increasing level of strength of the fasteners, the concept of ultra-high strength fasteners is being proposed, and the 14.9 grade and above fasteners can be primarily called ultra-high strength fasteners, while from the practical application perspective, the 14.9 grade is a grade with wider and urgent requirements in the current ultra-high strength fasteners, and the prospect of industrialized mass production is relatively large.
At present, the hot rolled wire rod raw material for manufacturing the 14.9-grade fastener is continuously developed by part of domestic steel factories, in the aspect of the hot rolled wire rod raw material, medium carbon steel with the carbon content of about 0.40 percent is generally used, higher Cr and Mo alloy elements are added, and a certain amount of V, nb micro alloy elements are added, so that the strength and hardenability of the wire rod are improved, and the mechanical property of the fastener after quenching and tempering heat treatment is ensured. Since C is a main element affecting cold plastic deformation of steel, the higher the carbon content is, the lower the plasticity of steel is; the two alloy elements of Cr and Mo can obviously improve the hardenability of steel, but also can reduce the plasticity of the steel, and obviously influence the metallographic structure and cold heading forming property of the hot rolled steel; v, ni can improve the strength and plasticity of steel, but is relatively expensive, and thus causes a significant increase in the manufacturing cost of the fastener, and is not suitable as a raw material for industrial mass production of fasteners. On the other hand, the existing 14.9-grade fastener has a remarkable delayed fracture problem, and most of the problems are caused by hydrogen-induced delayed fracture, and are also bottleneck problems of manufacturing and application of the 14.9-grade fastener.
The typical manufacturing process flow of the 14.9-grade bolt with the existing hot rolled wire rod as the raw material is as follows: hot rolling wire rod, spheroidizing annealing, acid washing, phosphating, saponification, drawing, cold heading forming, tempering heat treatment, surface treatment and dehydrogenation treatment, wherein the preparation of the hot rolling wire rod requires two spheroidizing annealing, two acid washing, two phosphating and saponification and two drawing, and then the cold heading forming and tempering heat treatment of the material are carried out; because the plasticity of the hot rolled wire rod is poor, direct drawing and cold heading forming cannot be performed, the production process flow of the bolt is longer, the processing cost is higher, and the cost of the hot rolled wire rod is higher, so that the cost of the 14.9-grade bolt is high, and the yield is limited.
In view of the above, in order to meet the requirements of manufacturing and application of ultra-high strength fasteners, it is highly desirable to develop a cold heading steel hot rolled wire rod with higher strength and hardenability, good plasticity and delayed fracture resistance, which shortens the manufacturing process flow of the 14.9-grade bolt, reduces the manufacturing cost, and solves the problem of delayed fracture of the bolt.
Disclosure of Invention
In order to solve the problems, the invention eliminates the use of Cr, mo, V, ni and other alloy elements by optimizing the design of chemical components, improves the strength and hardenability of steel by the combined use of C-Si-Mn-B elements, particularly controls rolling by combining a large coil production line with a hot rolling function, and enters a heat preservation tunnel for controlling cooling after rolling, thereby obviously improving the plasticity of the hot rolled wire rod; the Mn-S combination and the manufacturing process flow are combined in the chemical components, so that the hydrogen content is effectively controlled, a hydrogen trap is constructed, and the delayed fracture resistance of the material is improved. The cold heading steel hot rolled wire rod is used as a raw material, annealing is not needed, a 14.9-grade quenched and tempered bolt is produced through quenching and tempering, and the bolt has no delayed fracture problem.
The invention relates to a chemical composition design of a cold heading steel hot rolled wire rod for a delayed fracture resistant 14.9-grade quenched and tempered bolt, which comprises the following components in percentage by weight: 0.58 to 0.64 percent, si:0.35 to 0.45 percent, mn:1.70 to 1.90 percent, P: less than or equal to 0.010 percent, S:0.025 to 0.035 percent, al:0.020 to 0.040 percent, B: 0.0025-0.0035%, cr, ni, cu, mo% or less than 0.10%.
Compared with the existing hot rolled wire rod for manufacturing the 14.9-grade bolt, the wire rod component of the invention omits the use of Cr, mo, V, ni and other alloy elements; the strength and hardenability of the steel are improved through the combined use of the C-Si-Mn-B elements, and a foundation is provided for controlling rolling of a large coil production line with a hot rolling function, controlling cooling of the rolled coil after entering a heat preservation tunnel and improving the plasticity of the coil rod; through Mn-S combination, more irreversible hydrogen traps are constructed, hydrogen embrittlement is prevented, and the delayed fracture resistance of the wire rod is improved.
The preparation method of the cold heading steel hot rolled wire rod for the delayed fracture resistant 14.9-grade quenched and tempered bolt comprises a converter smelting process, an LF refining process, an RH vacuum refining process, a billet continuous casting process, a cogging rolling process, a rolled billet flaw detection process, a rolled billet grinding process and a wire rod rolling process.
Converter smelting process:
converter charging amount of the converter smelting process is 130 tons/furnace, wherein 90 percent of the converter charging amount is molten iron, and 10 percent of the converter charging amount is scrap steel; bottom argon blowing stirring is carried out in the whole smelting process of the converter, the tapping temperature is more than or equal to 1600 ℃, the tapping carbon is controlled within the range of 0.08-0.12%, and the tapping P is less than or equal to 0.008%; and (3) adding deoxidizer (silicon carbide), alloy (silicon-manganese alloy and high-carbon ferromanganese), carburant and slag in turn at 1/4 of tapping.
LF refining procedure:
adding a small amount of aluminum particles for deoxidization in the early stage of the LF refining process, and then feeding proper aluminum wires; and adding a boron iron wire and a sulfur iron wire in the later stage of LF smelting, and supplementing high-carbon ferromanganese and a carburant to adjust chemical components to a required range.
RH vacuum refining procedure:
the vacuum degree of RH vacuum smelting process is less than 67Pa, the circulation time is more than or equal to 30 minutes, and the RH total smelting time is 45-60 minutes; sampling and detecting chemical components 5 minutes before RH is finished, and performing gas analysis; after RH is broken, a proper amount of pure calcium wire is fed, and soft blowing is carried out for more than or equal to 15 minutes.
Billet continuous casting process:
the cross section of a continuous casting billet in the billet continuous casting process adopts a 300 mm-325 mm billet, the continuous casting superheat degree is controlled at 20-25 ℃, the constant pulling rate is controlled at 1.8+/-0.2 m/min, and the secondary cooling adopts strong cooling strength; an alkaline covering agent is adopted in the continuous casting process, argon protection between a ladle nozzle and a long nozzle is enhanced, and micro positive pressure of 1.5-2.0 Pa is maintained; using special covering slag for high-carbon steel; and after the continuous casting blank is taken off line, the continuous casting blank enters a slow cooling pit for slow cooling, the pit entering temperature is 800-900 ℃, and the slow cooling time is 48 hours.
Cogging and rolling steps:
the cogging rolling process adopts a step-by-step heating furnace to heat the continuous casting billet at 900-1200 ℃ for 3-4 hours; adopting 7 secondary parallel interchange rolling mills to roll continuous casting billets with the cross section of 300mm or 325mm into rolling billets with the cross section of 160mm or 160mm, and cogging rolling temperature of 1050-1100 ℃; and after the rolled blank is taken off line, the rolled blank enters a slow cooling pit for slow cooling, the pit entering temperature is 700-800 ℃, and the slow cooling time is 36 hours.
Flaw detection procedure of rolled blank:
and the flaw detection process of the rolled blank adopts a magnetic powder flaw detector and an ultrasonic flaw detector to detect the surface quality and the internal quality of the rolled blank, so that the internal quality and the external quality of the rolled blank are ensured to be normal.
Grinding the rolled blank:
the grinding process of the rolled blank adopts a grinding wheel type peeling machine to grind the steel blank, wherein the grinding depth of the face of the steel blank is 1.8-2.0 mm, and the grinding width of the corner of the steel blank is 15.0-20.0 mm.
And (3) a wire rod rolling procedure:
the coil rolling process adopts a large coil production line with a hot rolling function to roll, a rolled blank is heated for 1.5 to 2.5 hours at 750 to 1050 ℃ by a three-stage step heating furnace, a rough intermediate rolling and pre-finishing mill group adopts 900 to 950 ℃ to roll at a controlled temperature, a reducing sizing mill group adopts 750 to 800 ℃ to roll at a controlled temperature, and the rolled blank is cooled to 700 to 730 ℃ by a water tank to collect hot rolling after finishing rolling; immediately cooling the rolled coil in a heat preservation tunnel, cooling to below 120 ℃ at a cooling speed of 2.5-3.0 ℃/min, and naturally cooling to normal temperature in air after the coil is taken out of the heat preservation tunnel.
According to the invention, the rolled cold heading steel wire rod is subjected to quenching and tempering heat treatment (the quenching temperature is 860+/-10 ℃, the quenching medium is quenching oil, and the tempering temperature is 450+/-10 ℃) without annealing treatment, so that the produced bolt can meet the 14.9-level requirement, and the bolt has no delayed fracture problem.
Advantageous effects
The invention improves the strength and hardenability of steel by the combined use of C-Si-Mn-B elements, particularly controls rolling by combining a large coil production line with a hot rolling function, enters a heat preservation tunnel after rolling to control cooling, and obviously improves the plasticity of the hot rolled wire rod; the Mn-S combination and the manufacturing process flow are combined in the chemical components, so that the hydrogen content is effectively controlled, a hydrogen trap is constructed, and the delayed fracture resistance of the material is improved. The coil rod does not need to be added with Cr, mo, V, ni and other alloy elements, so that the production cost is obviously reduced;
the wire rod is used as a raw material to produce the 14.9-grade bolt, only one acid washing, one phosphorus saponification and one drawing are needed, and spheroidizing annealing and dehydrogenation treatment are not needed; compared with the prior art, the comprehensive production cost is obviously reduced, the production efficiency is obviously improved, the energy consumption is greatly reduced, the pollutant emission is greatly reduced, and the industrial bottleneck that the manufacturing cost of the 14.9-grade bolt is high and the yield is limited is solved.
Detailed Description
The invention comprises the following steps: the cold heading steel hot rolled wire rod for the delayed fracture resistant 14.9-grade quenched and tempered bolt comprises the following specific components:
Wt，％
| C | Si | Mn | P | S | Al | B | Cr、Ni、Cu、Mo |
| 0.58-0.64 | 0.35-0.45 | 1.70-1.90 | ≤0.010 | 0.025-0.035 | 0.020-0.040 | 0.0025-0.0035 | 0.032-0.065 |
the wire rod preparation process flow is as follows: converter smelting, LF refining, RH vacuum refining, billet continuous casting, cogging rolling, billet flaw detection, billet grinding and wire rod rolling.
The bolt preparation process flow comprises the following steps: hot rolling wire rod, pickling, phosphating, saponification, drawing, cold heading forming, tempering heat treatment and surface treatment.
Example 1
1. Chemical composition
The chemical composition design comprises the following components in percentage by weight: 0.59%, si:0.44%, mn:1.75%, P:0.006%, S:0.027%, al:0.029%, B:0.0028%, cr:0.04%, ni:0.01%, cu:0.02%, mo:0.02%.
2. Converter smelting
The converter charging amount of the converter smelting process is 130 tons/furnace, wherein 90 percent of molten iron and 10 percent of scrap steel are contained; bottom argon blowing stirring is carried out in the whole smelting process of the converter, the tapping temperature is 1605 ℃, the tapping carbon is 0.09%, and the tapping P content is 0.003%; 1/4 of tapping starts to sequentially add deoxidizer (120 kg/furnace of silicon carbide), alloy (1500 kg/furnace of silicon-manganese alloy and 1100 kg/furnace of high-carbon ferromanganese), carburant (650 kg/furnace), slag (500 kg of lime and 300kg of slag melting agent).
3. LF refining
Adding a small amount of aluminum particles (50 kg/furnace) for deoxidization in the early stage of the LF refining process, and then feeding proper (100 kg/furnace) aluminum wires; and adding a boron iron wire and a sulfur iron wire in the later stage of LF smelting, and supplementing high-carbon ferromanganese and a carburant to adjust chemical components to a required range.
4. RH vacuum refining
The vacuum degree of the RH vacuum smelting process is 65Pa, the circulation time is 38 minutes, and the RH total smelting time is 52 minutes; sampling and detecting chemical components 5 minutes before RH is finished, and performing gas analysis; after RH is broken, a proper amount of pure calcium wire is fed, and soft blowing is carried out for 23 minutes.
5. Billet continuous casting
The cross section of a continuous casting billet in the billet continuous casting process adopts a 300 mm-325mm billet, the continuous casting superheat degree is controlled at 25 ℃, the constant pull rate control of 1.8m/min is executed, and the secondary cooling adopts strong cooling strength; an alkaline covering agent is adopted in the continuous casting process, argon protection between a ladle nozzle and a long nozzle is enhanced, and micro positive pressure of 1.8Pa is maintained; using special covering slag for high-carbon steel; and (3) after the continuous casting blank is taken off line, entering a slow cooling pit for slow cooling, wherein the pit entering temperature is 858 ℃, and the slow cooling time is 48 hours.
6. Cogging and rolling
The cogging rolling process adopts a step-type heating furnace to heat the continuous casting billet, the heating temperature is 915-1170 ℃, and the heating time is 3.5 hours; the heated billet is rolled into a rolled billet with the cross section of 300mm or 325mm by adopting 7 secondary parallel interchange rolling mills, and the cogging rolling temperature is 1058-1077 ℃; and (5) after the rolled blank is off line, feeding the rolled blank into a slow cooling pit for slow cooling, wherein the pit feeding temperature is 726 ℃, and the slow cooling time is 36 hours.
7. Flaw detection of rolled blank
And the flaw detection process of the rolled blank adopts a magnetic powder flaw detector and an ultrasonic flaw detector to detect the surface quality and the internal quality of the rolled blank, so that the internal quality and the external quality of the rolled blank are ensured to be normal.
8. Grinding of rolled billets
The grinding process of the rolled blank adopts a grinding wheel type peeling machine to grind the steel blank, wherein the grinding depth of the face of the steel blank is 1.8mm, and the grinding width of the corner of the steel blank is 20.0mm.
9. Wire rod rolling
The coil rod rolling process adopts a large coil production line with a hot rolling function to roll, a rolled blank is heated for 1.8 hours at 758-1040 ℃ by a three-stage step heating furnace, a rough rolling mill and a pre-finishing mill group adopt 935 ℃ temperature control rolling, a reducing sizing mill group adopts 762 ℃ temperature control rolling, and the rolled blank is cooled to 710 ℃ through a water tank to be hot rolled and collected after finishing rolling; immediately cooling the rolled coil in a heat preservation tunnel, cooling to 102 ℃ at a cooling speed of 2.6 ℃/min, and naturally cooling to normal temperature in air after the coil is taken out of the heat preservation tunnel.
Example 2
1. Chemical composition
The chemical composition design comprises the following components in percentage by weight: 0.62%, si:0.36%, mn:1.73%, P:0.005%, S:0.033%, al:0.037%, B:0.0032%, cr:0.02%, ni:0.01%, cu:0.03%, mo:0.01%.
2. Converter smelting
Converter charging amount of the converter smelting process is 130 tons/furnace, wherein 90 percent of the converter charging amount is molten iron, and 10 percent of the converter charging amount is scrap steel; bottom argon blowing stirring is carried out in the whole smelting process of the converter, the tapping temperature is 1608 ℃, the tapping carbon is 0.10%, and the tapping P content is 0.006%; 1/4 of tapping starts to sequentially add deoxidizer (120 kg/furnace of silicon carbide), alloy (1500 kg/furnace of silicon-manganese alloy and 1050 kg/furnace of high-carbon ferromanganese), carburant (700 kg/furnace), slag (500 kg of lime and 300kg of slag melting agent).
3. LF refining
Adding a small amount of aluminum particles (60 kg/furnace) for deoxidization in the early stage of the LF refining process, and then feeding proper (110 kg/furnace) aluminum wires; and adding a boron iron wire and a sulfur iron wire in the later stage of LF smelting, and supplementing high-carbon ferromanganese and a carburant to adjust chemical components to a required range.
4. RH vacuum refining
The vacuum degree of the RH vacuum smelting process is 61Pa, the circulation time is 40 minutes, and the RH total smelting time is 55 minutes; sampling and detecting chemical components 5 minutes before RH is finished, and performing gas analysis; after RH is broken, a proper amount of pure calcium wire is fed, and soft blowing is carried out for 18 minutes.
5. Billet continuous casting
The cross section of a continuous casting billet in the continuous casting process of the billet adopts a billet 300mm x 325mm, the continuous casting superheat degree is controlled at 21 ℃, the constant pulling speed control of 1.9m/min is executed, and the secondary cooling adopts strong cooling strength; an alkaline covering agent is adopted in the continuous casting process, argon protection between a ladle nozzle and a long nozzle is enhanced, and micro positive pressure of 2.0Pa is maintained; using special covering slag for high-carbon steel; and (3) after the continuous casting blank is off line, feeding the continuous casting blank into a slow cooling pit for slow cooling, wherein the pit feeding temperature is 886 ℃, and the slow cooling time is 48 hours.
6. Cogging and rolling
The cogging rolling process adopts a step-by-step heating furnace to heat the continuous casting billet, the heating temperature is 931-1195 ℃, and the heating time is 3.6 hours; adopting 7 secondary parallel interchange rolling mills to roll continuous casting billets with the cross section of 300mm or 325mm into rolling billets with the cross section of 160mm or 160mm, and cogging rolling temperature of 1066-1082 ℃; and (5) after the rolled blank is off line, feeding the rolled blank into a slow cooling pit for slow cooling, wherein the pit feeding temperature is 751 ℃, and the slow cooling time is 36 hours.
7. Flaw detection of rolled blank
And the flaw detection process of the rolled blank adopts a magnetic powder flaw detector and an ultrasonic flaw detector to detect the surface quality and the internal quality of the rolled blank, so that the internal quality and the external quality of the rolled blank are ensured to be normal.
8. Grinding of rolled billets
The grinding process of the rolled blank adopts a grinding wheel type peeling machine to grind the steel blank, wherein the grinding depth of the face of the steel blank is 2.0mm, and the grinding width of the corner of the steel blank is 15.0mm.
9. Wire rod rolling
The coil rolling process adopts a large coil production line with a hot rolling function to roll, a rolled blank is heated for 2.3 hours at the temperature of 766-1049 ℃ by a three-section step heating furnace, a rough rolling mill, a middle rolling mill and a pre-finishing mill group adopt 945 ℃ to roll at a controlled temperature, a reducing sizing mill group adopts 763 ℃ to roll at a controlled temperature, and the rolled blank is cooled to 716 ℃ by a water tank to collect hot rolling after finishing rolling; immediately cooling the rolled coil in a heat preservation tunnel, cooling to 99 ℃ at a cooling speed of 2.8 ℃/min, and naturally cooling to normal temperature in air after the coil is taken out of the heat preservation tunnel.
Example 3
1. Chemical composition
The chemical composition design comprises the following components in percentage by weight: 0.63%, si:0.35%, mn:1.89%, P:0.006%, S:0.032%, al:0.036%, B:0.0033%, cr:0.02%, ni:0.01%, cu:0.03%, mo:0.02%.
2. Converter smelting
Converter charging amount of the converter smelting process is 130 tons/furnace, wherein 90 percent of the converter charging amount is molten iron, and 10 percent of the converter charging amount is scrap steel; bottom argon blowing stirring is carried out in the whole smelting process of the converter, the tapping temperature is 1608 ℃, the tapping carbon is 0.10%, and the tapping P content is 0.006%; 1/4 of tapping starts to sequentially add deoxidizer (120 kg/furnace of silicon carbide), alloy (1500 kg/furnace of silicon-manganese alloy and 1100 kg/furnace of high-carbon ferromanganese), carburant (700 kg/furnace), slag (500 kg of lime and 300kg of slag melting agent).
3. LF refining
Adding a small amount of aluminum particles (60 kg/furnace) for deoxidization in the early stage of the LF refining process, and then feeding proper (110 kg/furnace) aluminum wires; and adding a boron iron wire and a sulfur iron wire in the later stage of LF smelting, and supplementing high-carbon ferromanganese and a carburant to adjust chemical components to a required range.
4. RH vacuum refining
The vacuum degree of the RH vacuum smelting process is 61Pa, the circulation time is 40 minutes, and the RH total smelting time is 55 minutes; sampling and detecting chemical components 5 minutes before RH is finished, and performing gas analysis; after RH is broken, a proper amount of pure calcium wire is fed, and soft blowing is carried out for 18 minutes.
5. Billet continuous casting
The cross section of a continuous casting billet in the continuous casting process of the billet adopts a billet 300mm x 325mm, the continuous casting superheat degree is controlled at 21 ℃, the constant pulling speed control of 1.9m/min is executed, and the secondary cooling adopts strong cooling strength; an alkaline covering agent is adopted in the continuous casting process, argon protection between a ladle nozzle and a long nozzle is enhanced, and micro positive pressure of 2.0Pa is maintained; using special covering slag for high-carbon steel; and (3) after the continuous casting blank is off line, feeding the continuous casting blank into a slow cooling pit for slow cooling, wherein the pit feeding temperature is 885 ℃, and the slow cooling time is 48 hours.
6. Cogging and rolling
The cogging rolling process adopts a step-by-step heating furnace to heat the continuous casting billet, the heating temperature is 933-1196 ℃, and the heating time is 3.6 hours; adopting 7 secondary parallel interchange rolling mills to roll continuous casting billets with the cross section of 300mm or 325mm into rolling billets with the cross section of 160mm or 160mm, and cogging rolling temperature of 1068-1087 ℃; and after the rolled blank is taken off line, the rolled blank enters a slow cooling pit for slow cooling, the pit entering temperature is 753 ℃, and the slow cooling time is 36 hours.
7. Flaw detection of rolled blank
And the flaw detection process of the rolled blank adopts a magnetic powder flaw detector and an ultrasonic flaw detector to detect the surface quality and the internal quality of the rolled blank, so that the internal quality and the external quality of the rolled blank are ensured to be normal.
8. Grinding of rolled billets
The grinding process of the rolled blank adopts a grinding wheel type peeling machine to grind the steel blank, wherein the grinding depth of the face of the steel blank is 2.0mm, and the grinding width of the corner of the steel blank is 15.0mm.
9. Wire rod rolling
The coil rolling process adopts a large coil production line with a hot rolling function to roll, a rolled blank is heated for 2.3 hours at the temperature of 767-1044 ℃ by a three-section step heating furnace, a rough rolling mill, a medium rolling mill and a pre-finishing mill group adopt 946 ℃ to roll at the temperature control, a reducing sizing mill group adopts 765 ℃ to roll at the temperature control, and the rolled blank is cooled to 717 ℃ through a water tank to collect hot rolling after finishing rolling; immediately cooling the rolled coil in a heat preservation tunnel, cooling to 98 ℃ at a cooling speed of 2.8 ℃/min, and naturally cooling to normal temperature in air after the coil is taken out of the heat preservation tunnel.
Comparative example 1
The procedure of example 1 was repeated except that the content of B in the chemical component of step 1 of example 1 was replaced with 0.0010% by weight.
Comparative example 2
The procedure of example 1 was followed except that the content of S in the chemical component in step 1 of example 1 was replaced with 0.005% by weight.
Comparative example 3
The method comprises the steps of (1) putting the continuous casting billet into a slow cooling pit for slow cooling after the continuous casting billet is put off line in step 5 of example 1, putting the pit temperature 858 ℃ for 48 hours, replacing the continuous casting billet with the slow cooling pit for slow cooling after the continuous casting billet is put off line, naturally cooling to normal temperature in air, putting the rolled billet into the slow cooling pit for slow cooling after the continuous casting billet is put off line in step 6 of example 1, putting the pit temperature 726 ℃ for 36 hours, replacing the rolled billet with the slow cooling pit for pile cooling after the rolled billet is put off line, naturally cooling to normal temperature in air, and the other conditions are the same as in example 1.
Comparative example 4
Cooling the rolled steel sheet in the step 5 of the example 1 to 710 ℃ through a water tank, and collecting the heat curl; immediately cooling the rolled coil in a heat preservation tunnel under control, cooling to 102 ℃ at a cooling speed of 2.6 ℃/min, naturally cooling the coil in air to normal temperature after the coil is discharged out of the heat preservation tunnel, and ' replacing the coil with ' spinning by a spinning machine after finishing rolling, wherein the spinning temperature is 720 ℃, cooling the coil under control of a Steyr controlled cooling line after rolling, cooling to 450 ℃ at a cooling speed of 6 ℃/min, and naturally cooling the coil in air to normal temperature ', wherein other conditions are the same as those in example 1.
The hot rolled wire rod produced by the embodiment and the comparative example is used as a raw material, and the bolt manufacturing process flow comprises the following steps: hot rolled wire rod (Φ26.0mm), pickling, phosphating, saponification, drawing (Φ25.2mm), cold heading forming, tempering heat treatment (quenching, tempering heat treatment, quenching temperature 860+ -10 ℃, quenching medium is quenching oil, tempering temperature 450+ -10 ℃), surface treatment, mechanical properties of the produced bolts, cold heading cracking rate, delayed fracture comparison table 1 below:
TABLE 1
| Category(s) | Yield strength, MPa | Tensile strength, MPa | Yield ratio | Cold heading forming cracking rate of% | Delayed brittle fracture ratio% |
| Requirements for | ≥1260 | ≥1400 | ≥0.9 | ≤5 | ≤0.01 |
| Example 1 | 1360 | 1462 | 0.93 | 1.35 | 0 |
| Example 2 | 1392 | 1481 | 0.94 | 1.60 | 0 |
| Example 3 | 1409 | 1499 | 0.94 | 1.55 | 0 |
| Comparative example 1 | 1045 | 1215 | 0.86 | 2.50 | 0 |
| Comparative example 2 | 1275 | 1466 | 0.87 | 4.50 | 25 |
| Comparative example 3 | 1235 | 1403 | 0.88 | 3.20 | 18 |
| Comparative example 4 | 1305 | 1450 | 0.90 | 68.66 | 10 |
Claims (8)
1. A delay fracture resistant 14.9 grade quenched and tempered cold heading steel hot rolled wire rod for a bolt is characterized in that: the cold heading steel hot rolled wire rod comprises the following chemical components in percentage by weight: 0.58 to 0.64 percent, si:0.35 to 0.45 percent, mn:1.70 to 1.90 percent, P: less than or equal to 0.010 percent, S:0.025 to 0.035 percent, al:0.020 to 0.040 percent, B: 0.0025-0.0035%, cr, ni, cu, mo% or less than 0.10%.
2. A preparation method of a cold heading steel hot-rolled wire rod for a delayed fracture resistant 14.9-grade quenched and tempered bolt is characterized by comprising the following steps: the preparation method comprises the following steps: converter smelting, LF refining, RH vacuum refining, billet continuous casting, cogging and rolling, flaw detection of rolled billets, grinding of rolled billets and wire rod rolling.
3. The method for preparing the cold heading steel hot-rolled wire rod for the delayed fracture resistant 14.9-grade quenched and tempered bolt, which is characterized by comprising the following steps of: the converter charging amount is 130 tons/furnace in the converter smelting process, wherein 90 percent of molten iron and 10 percent of scrap steel are used; bottom argon blowing stirring is carried out in the whole smelting process of the converter, the tapping temperature is more than or equal to 1600 ℃, the tapping carbon is controlled within the range of 0.08-0.12%, and the tapping P is less than or equal to 0.008%; and (4) adding deoxidizer, alloy, carburant and slag in turn from 1/4 of tapping.
4. The method for preparing the cold heading steel hot-rolled wire rod for the delayed fracture resistant 14.9-grade quenched and tempered bolt, which is characterized by comprising the following steps of: adding aluminum particles for deoxidization in the early stage of LF refining, and then feeding an aluminum wire; adding a boron iron wire and a sulfur iron wire in the later stage of LF smelting, and supplementing high-carbon ferromanganese and a carburant, and adjusting chemical components to a required range; the vacuum degree of RH vacuum smelting process is less than 67Pa, the circulation time is more than or equal to 30 minutes, and the RH total smelting time is 45-60 minutes; sampling and detecting chemical components 5 minutes before RH is finished, and performing gas analysis; and feeding pure calcium wires after RH is broken, and soft blowing is performed for more than or equal to 15 minutes.
5. The method for preparing the cold heading steel hot-rolled wire rod for the delayed fracture resistant 14.9-grade quenched and tempered bolt, which is characterized by comprising the following steps of: the cross section of a continuous casting billet adopts a 300mm x 325mm billet in the continuous casting process of the billet, the superheat degree of continuous casting is controlled at 20-25 ℃, the constant pulling rate of 1.8+/-0.2 m/min is controlled, and the second cooling adopts strong cooling strength; an alkaline covering agent is adopted in the continuous casting process, argon protection between a ladle nozzle and a long nozzle is enhanced, and micro positive pressure of 1.5-2.0 Pa is maintained; using special covering slag for high-carbon steel; and after the continuous casting blank is taken off line, the continuous casting blank enters a slow cooling pit for slow cooling, the pit entering temperature is 800-900 ℃, and the slow cooling time is 48 hours.
6. The method for preparing the cold heading steel hot-rolled wire rod for the delayed fracture resistant 14.9-grade quenched and tempered bolt, which is characterized by comprising the following steps of: the continuous casting billet is heated by a step heating furnace for 3-4 hours at 900-1200 ℃; adopting 7 secondary parallel interchange rolling mills to roll continuous casting billets with the cross section of 300mm or 325mm into rolling billets with the cross section of 160mm or 160mm, and cogging rolling temperature of 1050-1100 ℃; and after the rolled blank is taken off line, the rolled blank enters a slow cooling pit for slow cooling, the pit entering temperature is 700-800 ℃, and the slow cooling time is 36 hours.
7. The method for preparing the cold heading steel hot-rolled wire rod for the delayed fracture resistant 14.9-grade quenched and tempered bolt, which is characterized by comprising the following steps of: the flaw detection of the rolled blank is carried out by respectively adopting a magnetic powder flaw detector and an ultrasonic flaw detector to detect the surface quality and the internal quality of the rolled blank, so that the internal quality and the external quality of the rolled blank are ensured to be normal; the grinding process of the rolled blank adopts a grinding wheel type peeling machine to grind the steel blank, wherein the grinding depth of the face of the steel blank is 1.8-2.0 mm, and the grinding width of the corner of the steel blank is 15.0-20.0 mm.
8. The method for preparing the cold heading steel hot-rolled wire rod for the delayed fracture resistant 14.9-grade quenched and tempered bolt, which is characterized by comprising the following steps of: the coil rod rolling adopts a large coil production line with a hot rolling function for rolling, a rolled blank is heated for 1.5 to 2.5 hours at 750 to 1050 ℃ by a three-stage step heating furnace, a rough rolling mill, a medium rolling mill and a pre-finishing mill group adopt 900 to 950 ℃ for temperature control rolling, a reducing sizing mill group adopts 750 to 800 ℃ for temperature control rolling, and the rolled blank is cooled to 700 to 730 ℃ for hot rolling collection by a water tank after finishing rolling; immediately cooling the rolled coil in a heat preservation tunnel, cooling to below 120 ℃ at a cooling speed of 2.5-3.0 ℃/min, and naturally cooling to normal temperature in air after the coil is taken out of the heat preservation tunnel.
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| CN116497261A (en) * | 2023-06-19 | 2023-07-28 | 张家港荣盛特钢有限公司 | Vulcanizing cold heading steel wire rod and preparation method and application thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN116497261A (en) * | 2023-06-19 | 2023-07-28 | 张家港荣盛特钢有限公司 | Vulcanizing cold heading steel wire rod and preparation method and application thereof |
| CN116497261B (en) * | 2023-06-19 | 2023-09-12 | 张家港荣盛特钢有限公司 | Vulcanizing cold heading steel wire rod and preparation method and application thereof |
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