CN117139378A - Controlled rolling and cooling process for large coil of high-carbon alloy tool steel without annealing - Google Patents
Controlled rolling and cooling process for large coil of high-carbon alloy tool steel without annealing Download PDFInfo
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- CN117139378A CN117139378A CN202310939742.XA CN202310939742A CN117139378A CN 117139378 A CN117139378 A CN 117139378A CN 202310939742 A CN202310939742 A CN 202310939742A CN 117139378 A CN117139378 A CN 117139378A
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- 238000005096 rolling process Methods 0.000 title claims abstract description 98
- 238000001816 cooling Methods 0.000 title claims abstract description 52
- 229910001315 Tool steel Inorganic materials 0.000 title claims abstract description 35
- 229910001339 C alloy Inorganic materials 0.000 title claims abstract description 32
- 238000000137 annealing Methods 0.000 title claims abstract description 22
- 238000000034 method Methods 0.000 title claims abstract description 22
- 238000004321 preservation Methods 0.000 claims abstract description 41
- 238000010438 heat treatment Methods 0.000 claims abstract description 35
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 34
- 239000010959 steel Substances 0.000 claims abstract description 34
- 238000009749 continuous casting Methods 0.000 claims abstract description 17
- 238000005452 bending Methods 0.000 claims abstract description 10
- 229910001562 pearlite Inorganic materials 0.000 claims abstract description 9
- 239000000126 substance Substances 0.000 claims description 11
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 8
- 239000000203 mixture Substances 0.000 claims description 8
- 238000002791 soaking Methods 0.000 claims description 6
- 229910052720 vanadium Inorganic materials 0.000 claims description 6
- 230000033764 rhythmic process Effects 0.000 claims description 5
- 239000012535 impurity Substances 0.000 claims description 4
- 229910052742 iron Inorganic materials 0.000 claims description 4
- 229910052759 nickel Inorganic materials 0.000 claims description 3
- 229910052802 copper Inorganic materials 0.000 claims description 2
- 238000004519 manufacturing process Methods 0.000 abstract description 6
- 239000002994 raw material Substances 0.000 abstract description 2
- 238000005261 decarburization Methods 0.000 description 11
- 230000000052 comparative effect Effects 0.000 description 8
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 6
- 229910052799 carbon Inorganic materials 0.000 description 6
- 230000000694 effects Effects 0.000 description 6
- 229910045601 alloy Inorganic materials 0.000 description 5
- 239000000956 alloy Substances 0.000 description 5
- 239000011651 chromium Substances 0.000 description 5
- 238000010586 diagram Methods 0.000 description 5
- 229910000734 martensite Inorganic materials 0.000 description 5
- 239000000463 material Substances 0.000 description 5
- 229910000677 High-carbon steel Inorganic materials 0.000 description 3
- 229910052804 chromium Inorganic materials 0.000 description 3
- 239000000498 cooling water Substances 0.000 description 3
- 229910052710 silicon Inorganic materials 0.000 description 3
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 2
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 2
- 238000002788 crimping Methods 0.000 description 2
- 238000009792 diffusion process Methods 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 238000009413 insulation Methods 0.000 description 2
- 238000001556 precipitation Methods 0.000 description 2
- 239000010703 silicon Substances 0.000 description 2
- 238000009987 spinning Methods 0.000 description 2
- 229910000975 Carbon steel Inorganic materials 0.000 description 1
- 229910000954 Medium-carbon steel Inorganic materials 0.000 description 1
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 1
- 238000003723 Smelting Methods 0.000 description 1
- 238000005275 alloying Methods 0.000 description 1
- 229910001563 bainite Inorganic materials 0.000 description 1
- 239000010962 carbon steel Substances 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 230000002939 deleterious effect Effects 0.000 description 1
- 238000005098 hot rolling Methods 0.000 description 1
- 239000003595 mist Substances 0.000 description 1
- 229910052750 molybdenum Inorganic materials 0.000 description 1
- 239000011733 molybdenum Substances 0.000 description 1
- 229910052758 niobium Inorganic materials 0.000 description 1
- 239000010955 niobium Substances 0.000 description 1
- GUCVJGMIXFAOAE-UHFFFAOYSA-N niobium atom Chemical compound [Nb] GUCVJGMIXFAOAE-UHFFFAOYSA-N 0.000 description 1
- 238000005554 pickling Methods 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 238000007670 refining Methods 0.000 description 1
- 238000005204 segregation Methods 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- 238000010583 slow cooling Methods 0.000 description 1
- 239000002436 steel type Substances 0.000 description 1
- 238000004381 surface treatment Methods 0.000 description 1
- 238000005496 tempering Methods 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 description 1
- 229910052721 tungsten Inorganic materials 0.000 description 1
- 239000010937 tungsten Substances 0.000 description 1
- LEONUFNNVUYDNQ-UHFFFAOYSA-N vanadium atom Chemical compound [V] LEONUFNNVUYDNQ-UHFFFAOYSA-N 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B37/00—Control devices or methods specially adapted for metal-rolling mills or the work produced thereby
-
- 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
- B21B1/18—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 in a continuous process
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B15/00—Arrangements for performing additional metal-working operations specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B27/00—Rolls, roll alloys or roll fabrication; Lubricating, cooling or heating rolls while in use
- B21B27/02—Shape or construction of rolls
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B45/00—Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills
- B21B45/004—Heating the product
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B45/00—Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills
- B21B45/02—Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills for lubricating, cooling, or cleaning
- B21B45/0203—Cooling
- B21B45/0206—Coolants
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B15/00—Arrangements for performing additional metal-working operations specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills
- B21B2015/0057—Coiling the rolled product
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Physics & Mathematics (AREA)
- Geometry (AREA)
- Heat Treatment Of Strip Materials And Filament Materials (AREA)
Abstract
The invention belongs to the technical field of tool steel rolling, and particularly relates to a controlled rolling and cooling process for large coils of high-carbon alloy tool steel without annealing. The production of the large coil of the high-carbon alloy tool steel without annealing uses continuous casting billets as raw materials, adopts a heat accumulating type heating furnace to heat, finishes rough intermediate rolling and pre-finish rolling through a horizontal-vertical alternating type two-roller mill, finishes rolling to the finished product specification through a three-roller mill, then uses a hot coiling machine to curl and collect, and finally controls cooling through a heat preservation tunnel. The invention enables the hot rolled high-carbon alloy tool steel to obtain the pearlite structure in the large coil by the innovative application of the large coil rolling line controlled rolling and cooling process, greatly improves the plasticity, simultaneously ensures that the depth of a decarburized layer meets the requirement, meets the processing of no annealing drawing of hexagonal steel wires and cold bending forming of downstream users, and realizes the annealing-free use of the large coil of the high-carbon alloy tool steel.
Description
Technical Field
The invention belongs to the technical field of tool steel rolling, and relates to a controlled rolling and cooling process for large coils of high-carbon alloy tool steel without annealing.
Background
Tool steel is used for manufacturing tools such as wrenches, cutters, drills, taps, measuring tools, saw blades and the like, and special applications require higher hardness and wear resistance and maintain certain toughness. Tool steels are generally classified into three main categories, carbon tool steels, alloy tool steels and high-speed tool steels, according to different chemical compositions, wherein alloy tool steels are widely used. Alloy tool steel generally refers to a type of steel in which alloying elements such as chromium, molybdenum, tungsten, vanadium, niobium and the like are added on the basis of carbon steel so as to improve the hardness, wear resistance, heat resistance, toughness and hardenability. At present, most of domestic common alloy tool steels are medium carbon steel or high carbon steel, and the carbon content is mainly concentrated at 0.40% -0.80%, wherein the alloy tool steels with carbon content of more than 0.60% are commonly called high carbon alloy tool steels. Because the high-carbon alloy tool steel has higher hardness and wear resistance and better hardenability, the high-carbon alloy tool steel is currently the main material for manufacturing high-grade hexagonal wrenches, and the hot-rolled rod wire is the main product form of the tool steel.
The high-carbon alloy tool steel has higher carbon content, so that the hardness and wear resistance are improved, the silicon content and the chromium content are also higher, the chemical components determine that the metallographic structure in the hot rolling state is easy to have low-temperature structures such as martensite, bainite and the like, and the plasticity of the material is reduced; on the other hand, the decarburization sensitivity of the steel is obviously increased due to high carbon and high silicon, decarburization is very easy to occur in the heating and cooling after rolling in the process of rolling the rod and wire, and the requirements of tool steel on the decarburization are strict; therefore, the control of metallographic structure and decarburization is always a difficulty of a rolling tool steel bar and wire rod in a steelworks, the problem also limits the processing technology of downstream users, and the direct drawing, cold bending and other processes can cause material cracking or breaking due to poor plasticity of the hot rolled bar and wire rod, so that the downstream users have to carry out annealing treatment for 1-2 times before processing, and decarburization is easy to occur in the annealing process. CN202010267215.5 is a controlled rolling and cooling process for reducing the depth of decarburized layer of steel wire rod of high-carbon alloy tool, through scientific controlled rolling and controlled cooling combination, decarburization in two-phase region is effectively inhibited, the whole course low-temperature heating scheme is adopted, martensite structure is easy to exist in metallographic structure to lead to material drawing and cold bending fracture, the application effects of drawing hexagonal steel wire without annealing and cold bending forming cannot be achieved, especially for the scheme with higher Cr and Si content and more serious element segregation problem, the scheme is more difficult to be applied. The finish rolling equipment is a two-roll mill, applicable specifications produced by adopting the two-roll mill and a wire laying machine can not exceed phi 26.0mm in the current industry, wire laying and Sitaier molar controlled cooling lines are adopted for controlled cooling after rolling, and the controlled cooling scheme is a combined cooling scheme of firstly using a water mist blower to rapidly cool and then covering a heat preservation cover to slowly cool, so that the problems of decarburization are mainly solved, and meanwhile, precipitation of martensite can be reduced, but the effect of obtaining pearlite can not be achieved. CN201911311641.8 is a production method of hot-rolled high-carbon steel, the product is hot-rolled steel plate, the steel grade is high-carbon steel, and under the conditions of product form and steel grade, pearlite can be obtained by adopting conventional rolling process, and is different from the production process of hot-rolled large coil, and the steel grade is high-carbon alloy steel. The difference in product morphology and steel type results in quite different difficulties in obtaining pearlitic texture. The product is hot rolled large coil, and the steel grade is martensite structure which is necessarily existed in the metallographic structure of the conventional process under the production process condition of high-carbon alloy steel, so that the drawing and cold bending forming without annealing cannot be performed. In the field of high carbon alloy tool steel rolling, how to obtain pearlite structures belongs to the technical problem in the field.
In summary, a suitable controlled rolling and cooling process is developed, the metallographic structure and decarburization of the hot rolled rod and wire of the high-carbon alloy tool steel are improved, the plasticity of the material is improved, the annealing process is avoided, the decarburization risk is reduced, and the processing requirements of downstream users on drawing the hexagonal steel wire without annealing and cold bending are met, so that the method is a problem to be solved in the current steel mill.
Disclosure of Invention
In order to solve the problems, the invention enables the hot rolled high carbon alloy tool steel to obtain the pearlite structure in the large coil by innovative application of the rolling line controlled rolling and cooling process in the large coil, greatly improves the plasticity, simultaneously ensures that the depth of a decarburized layer meets the requirements, satisfies the processing of drawing the hexagonal steel wire without annealing and cold bending by downstream users, and realizes the annealing-free use of the large coil of the high carbon alloy tool steel.
The invention relates to a controlled rolling and cooling process for a large coil of high-carbon alloy tool steel without annealing, which comprises a controlled rolling and cooling process and chemical components, and is described in detail below.
And (3) a rolling and cooling control process:
the rolling process flow comprises continuous casting billet heating, rough intermediate rolling, pre-finish rolling, hot coiling, heat preservation tunnel controlled cooling and bundling.
Heating a continuous casting blank:
heating the continuous casting blank by adopting a heat accumulating type heating furnace, wherein the section of the continuous casting blank is 160mm in 160mm, and the heating furnace is divided into a preheating section, a heating section and a soaking section; the heating temperature is 900-1200 ℃, wherein the preheating first-stage temperature is 900-950 ℃, the preheating second-stage temperature is 1000-1050 ℃, the heating-stage temperature is 1150-1200 ℃, and the soaking-stage temperature is 1000-1050 ℃. Wherein the heating section uses high temperature heating of 1150-1200 ℃ to facilitate the subsequent acquisition of pearlite metallographic structure. The heating scheme can ensure the diffusion effect, reduce decarburization, realize lower temperature of the steel after high-temperature diffusion and provide conditions for subsequent rolling temperature.
Rough intermediate rolling and pre-finish rolling:
the rough intermediate rolling and pre-finishing mill group adopts a horizontal interchange type two-roll mill to roll, and heated billet is rolled into an intermediate rolled piece; wherein the number of the rough and medium rolling frames is 14, the number of the pre-finish rolling frames is 4, and the rolling temperature of the rough and medium rolling and pre-finish rolling groups is 900-980 ℃. The rough rolling, the medium rolling and the pre-finish rolling are taken as basic deformation stages, and the whole rolling temperature is ensured to meet the requirement.
Finish rolling:
the finishing mill group adopts 5 three-roller mill to roll the intermediate rolled piece to the finished product specification, and the rolling temperature of the finishing mill group is 800-840 ℃. And 5, cooling water among three-high rolling mills is started, so that temperature rise of rolled pieces is restrained, temperature difference of the rolled pieces is reduced, and rolling control effect is ensured. The applicable specification of the large coil is phi 25.0-42.0 mm.
And (3) hot coiling:
and (3) coiling and collecting the large coil after rolling by using a hot coiling machine, wherein the coiling temperature is 700-730 ℃, and then immediately transferring the coil to a heat preservation tunnel for controlling and cooling. The operation time from hot coiling to a heat preservation tunnel is reduced, and the temperature drop of a large coil is controlled to be less than or equal to 50 ℃. The crimping temperature directly affects the subsequent transformation of the metallurgical structure of the steel.
Heat preservation tunnel accuse cooling:
the temperature of the large coil entering the heat preservation tunnel is controlled to be 650-680 ℃, the large coil enters the heat preservation tunnel in a mode of off-line at intervals, namely, a hollow step is arranged between every two large coils, the heat preservation cover of the heat preservation tunnel is fully opened, the stepping rhythm of the heat preservation tunnel is adjusted, the time of the large coil in the heat preservation tunnel is ensured to be 30-40 min, the cooling rate is 0.20-0.22 ℃/s, and the temperature of the large coil out of the heat preservation cover is controlled to be less than 200 ℃. The invention adopts a hot curl and heat preservation tunnel after rolling, the cold control scheme is slow cooling in the whole process, the heat preservation cooling time is improved, the phase change problem of steel is mainly solved, the steel obtains a pearlite structure, the precipitation of martensite is avoided, and the decarburization is effectively inhibited while the aim of controlling the structure is fulfilled.
Bundling:
and transferring the large coil after the controlled cooling to a bundling machine for bundling, wherein the bundling temperature is less than 100 ℃, and the bundling pressure is 10-15 tons by adopting a steel belt bundling machine.
The chemical components are as follows:
the main chemical composition range of the large coil of the annealing-free high-carbon alloy tool steel is as follows in percentage by weight: 0.69 to 0.75 percent, si:1.40 to 1.60 percent, mn:0.50 to 0.70 percent, cr:1.00 to 1.20 percent of Ni, 0.10 to 0.20 percent of V, 0.15 to 0.20 percent of V, 0.015 to 0.030 percent of Al, less than or equal to 0.025 percent of P, less than or equal to 0.025 percent of S, less than or equal to 0.20 percent of Cu, and the balance of iron and unavoidable impurities.
The high-carbon alloy tool steel has the carbon content reaching the level of 0.7%, the Si content exceeding 1.40%, and the Cr content exceeding 1.0%, and is additionally added with two microalloy elements of Ni and V, and simultaneously added with a small amount of Al. Other elements are controlled as residual or deleterious elements.
The invention enables the hot rolled high-carbon alloy tool steel to obtain the pearlite structure in the large coil by the innovative application of the large coil rolling line controlled rolling and cooling process, greatly improves the plasticity, simultaneously ensures that the depth of a decarburized layer meets the requirement, meets the processing of no annealing drawing of hexagonal steel wires and cold bending forming of downstream users, and realizes the annealing-free use of the large coil of the high-carbon alloy tool steel.
Drawings
FIG. 1 is a metallographic structure diagram of the wire rod produced in example 1.
Fig. 2 is a metallographic structure diagram of the wire rod produced in example 2.
Fig. 3 is a metallographic structure diagram of the wire rod produced in comparative example 1.
FIG. 4 is a metallographic structure diagram of the wire rod produced in comparative example 2.
FIG. 5 is a metallographic structure diagram of the wire rod produced in comparative example 3.
Detailed Description
The invention comprises the following steps: the specific chemical composition of the 70SiCrV coil of the high carbon alloy tool steel without annealing is as follows:
Wt，％
| C | Si | Mn | Cr | Ni | V | Al | P、S | Cu |
| 0.69-0.75 | 1.40-1.60 | 0.50-0.70 | 1.00-1.20 | 0.10-0.20 | 0.15-0.20 | 0.015-0.030 | ≤0.025 | ≤0.20 |
the preparation process flow of the wire rod comprises the following steps: primary smelting of a converter, RH vacuum refining, billet continuous casting, cogging rolling, wire rod rolling and wire rod controlled cooling.
The applicable specification of the large coil is phi 25.0-42.0 mm, and the embodiment takes phi 26.0mm as an example.
Example 1
1. Chemical composition
The chemical composition design comprises the following components in percentage by weight: 0.70%, si:1.45%, mn:0.68%, cr:1.09%, ni 0.14%, V0.16%, al 0.016%, P0.010%, S0.006%, cu 0.05%, and the balance iron and unavoidable impurities.
2. And (3) a rolling and cooling control process:
the rolling process flow comprises continuous casting billet heating, rough intermediate rolling, pre-finish rolling, hot coiling, heat preservation tunnel controlled cooling and bundling.
Heating a continuous casting blank:
heating the continuous casting blank by adopting a heat accumulating type heating furnace, wherein the section of the continuous casting blank is 160mm in 160mm, and the heating furnace is divided into a preheating section, a heating section and a soaking section; the heating temperature is 905-1190 ℃, wherein the preheating temperature of the first section is 905-940 ℃, the preheating temperature of the second section is 1010-1038 ℃, the heating temperature of the heating section is 1160-1190 ℃, and the soaking temperature of the soaking section is 1015-1031 ℃.
Rough intermediate rolling and pre-finish rolling:
the rough intermediate rolling and pre-finishing mill group adopts a horizontal interchange type two-roll mill to roll, and heated billet is rolled into an intermediate rolled piece; wherein the number of the rough and medium rolling frames is 14, the number of the pre-finish rolling frames is 4, and the rolling temperature of the rough and medium rolling and pre-finish rolling groups is 907-969 ℃.
Finish rolling:
the finishing mill group adopts 5 three-roller mill to roll the intermediate rolled piece to the finished product specification, and the rolling temperature of the finishing mill group is 802-832 ℃. And 5, cooling water among three-high rolling mills is started, so that temperature rise of rolled pieces is restrained, temperature difference of the rolled pieces is reduced, and rolling control effect is ensured.
And (3) hot coiling:
and (3) coiling and collecting the large coil after rolling by using a hot coiling machine, wherein the coiling temperature is between 705 and 728 ℃, and then immediately transferring the coil to a heat preservation tunnel for controlled cooling. The operation time from hot coiling to a heat preservation tunnel is reduced, and the temperature drop of a large coil is controlled to be less than or equal to 50 ℃.
Heat preservation tunnel accuse cooling:
the temperature of the large coil entering the heat-preserving tunnel is controlled to 661-670 ℃, the large coil enters the heat-preserving tunnel in a mode of off-line at intervals, namely, a space is arranged between every two large coils, the heat-preserving covers of the heat-preserving tunnel are all opened, the stepping rhythm of the heat-preserving tunnel is adjusted, the time of the large coil in the heat-preserving tunnel is ensured to be 35min, the cooling rate is 0.20 ℃/s, and the temperature of the large coil exiting the heat-preserving cover is controlled to be 180 ℃.
Bundling:
and transferring the large coil after the controlled cooling to a bundling machine for bundling, wherein the bundling temperature is less than 100 ℃, and the bundling pressure is 12 tons by adopting a steel belt bundling machine.
Example 2
1. Chemical composition
The chemical composition design comprises the following components in percentage by weight: 0.75%, si:1.58%, mn:0.55%, cr:1.15%, ni 0.18%, V0.19%, al 0.022%, P0.012%, S0.010%, cu 0.09%, and the balance of iron and unavoidable impurities.
2. And (3) a rolling and cooling control process:
the rolling process flow comprises continuous casting billet heating, rough intermediate rolling, pre-finish rolling, hot coiling, heat preservation tunnel controlled cooling and bundling.
Heating a continuous casting blank:
heating the continuous casting blank by adopting a heat accumulating type heating furnace, wherein the section of the continuous casting blank is 160mm in 160mm, and the heating furnace is divided into a preheating section, a heating section and a soaking section; the heating temperature is 911-1198 ℃, wherein the preheating first-stage temperature is 911-949 ℃, the preheating second-stage temperature is 1022-1046 ℃, the heating-stage temperature is 1158-1193 ℃, and the soaking-stage temperature is 1012-1044 ℃.
Rough intermediate rolling and pre-finish rolling:
the rough intermediate rolling and pre-finishing mill group adopts a horizontal interchange type two-roll mill to roll, and heated billet is rolled into an intermediate rolled piece; wherein the number of the rough and medium rolling frames is 14, the number of the pre-finish rolling frames is 4, and the rolling temperature of the rough and medium rolling and pre-finish rolling groups is between 911 and 972 ℃.
Finish rolling:
the finishing mill group adopts 5 three-roller mill to roll the intermediate rolled piece to the finished product specification, and the rolling temperature of the finishing mill group is 808-833 ℃. And 5, cooling water among three-high rolling mills is started, so that temperature rise of rolled pieces is restrained, temperature difference of the rolled pieces is reduced, and rolling control effect is ensured.
And (3) hot coiling:
and (3) coiling and collecting the large coil after rolling by using a hot coiling machine, wherein the coiling temperature is 703-725 ℃, and then immediately transferring the coil to a heat preservation tunnel for controlled cooling. The operation time from hot coiling to a heat preservation tunnel is reduced, and the temperature drop of a large coil is controlled to be less than or equal to 50 ℃.
Heat preservation tunnel accuse cooling:
the temperature of the large coil entering the heat-preserving tunnel is controlled to 659-668 ℃, the large coil enters the heat-preserving tunnel in a mode of off-line at intervals, namely, a space is arranged between every two large coils, the heat-preserving covers of the heat-preserving tunnel are all opened, the stepping rhythm of the heat-preserving tunnel is adjusted, the time of the large coil in the heat-preserving tunnel is ensured to be 36min, the cooling rate is 0.21 ℃/s, and the temperature of the large coil exiting the heat-preserving cover is controlled to be 158 ℃.
Bundling:
and transferring the large coil after the controlled cooling to a bundling machine for bundling, wherein the bundling temperature is less than 100 ℃, and the bundling pressure is 13 tons by adopting a steel belt bundling machine.
Comparative example 1
The temperature of the hot coil in the step 2 of the example 1 is replaced by 900-930 ℃, the temperature of the large coil entering the heat insulation tunnel is 832-870 ℃ and the temperature of the large coil exiting the heat insulation cover is 405 ℃ under the influence of the adjustment of the temperature of the coil, and other conditions are the same as the example 1.
Comparative example 2
The heat preservation tunnel cooling control scheme in the step 2 of the embodiment 1 is replaced by' the temperature of the large coil entering the heat preservation tunnel is controlled to 661-670 ℃, the large coil enters the heat preservation tunnel in a continuous off-line mode, namely, blank spaces cannot exist between every two large coils, the heat preservation tunnel heat preservation covers are all closed, the stepping rhythm of the heat preservation tunnels is adjusted, the time of the large coil in the heat preservation tunnel is ensured to be 35min, the cooling rate is 0.10 ℃/s, the temperature of the large coil exiting the heat preservation covers is controlled to 455 ℃, and other conditions are the same as those in the embodiment 1.
Comparative example 3
The heat crimping and heat preservation tunnel cooling scheme in the step 2 of the embodiment 1 is replaced by 'rolling is performed by adopting spinning and stelmor cooling control line cooling', the spinning temperature is 705-728 ℃, the cooling rate is 0.2 ℃/s, the cooling control time is 19min, the cooling control end off-line temperature is 492 ℃, and other conditions are the same as the embodiment 1.
The inventive example and comparative example produced a high carbon alloy tool steel large coil/wire rod (comparative example 3 produced a wire rod) and the example was exemplified by a phi 26.0mm specification. The hexagonal wrench is manufactured by using a large coil/wire rod as a raw material through the processing technology of pickling, phosphating, drawing an outer hexagonal steel wire, cold bending by 90 degrees, forming, turning, tempering heat treatment and surface treatment. The results of the use of the high carbon alloy tool steel large coil/wire rod test and the processing of the hexagonal wrench produced by adopting different schemes are compared with the following table 1:
TABLE 1
The metallographic structures of the large coil/wire rod of the high-carbon alloy tool steel produced by adopting different schemes are shown in the following figures 1-5.
Claims (3)
1. A rolling and cooling control method for a large coil of high-carbon alloy tool steel without annealing is characterized by comprising the following steps of: the rolling process flow comprises continuous casting billet heating, rough intermediate rolling, pre-finish rolling, hot coiling, heat preservation tunnel controlled cooling and bundling;
the continuous casting billet is heated by a heat accumulating type heating furnace, the section of the continuous casting billet is 160mm x 160mm, and the heating furnace is divided into a preheating section, a heating section and a soaking section; the heating temperature is 900-1200 ℃, wherein the preheating first-stage temperature is 900-950 ℃, the preheating second-stage temperature is 1000-1050 ℃, the heating-stage temperature is 1150-1200 ℃, and the soaking-stage temperature is 1000-1050 ℃;
the rough intermediate rolling and pre-finishing mill group adopts a horizontal interchange type two-roll mill to roll, and heated billet is rolled into an intermediate rolled piece; wherein the rolling temperature of the rough rolling mill, the medium rolling mill and the pre-finishing mill group is 900-980 ℃;
the finishing mill group adopts 5 three-roller mill to roll the intermediate rolled piece to the specification of the finished product, and the rolling temperature of the finishing mill group is 800-840 ℃;
after rolling, coiling and collecting the large coil by using a hot coiling machine, wherein the coiling temperature is 700-730 ℃, and then immediately transferring the coil to a heat preservation tunnel for controlling and cooling;
the temperature of the large coil entering the heat preservation tunnel is controlled to be 650-680 ℃, the large coil enters the heat preservation tunnel in a mode of off-line at intervals, namely, a space is arranged between every two large coils, the heat preservation cover of the heat preservation tunnel is fully opened, the stepping rhythm of the heat preservation tunnel is adjusted, the time of the large coil in the heat preservation tunnel is ensured to be 30-40 min, the cooling rate is 0.20-0.22 ℃/s, and the temperature of the large coil out of the heat preservation cover is controlled to be less than 200 ℃;
and transferring the large coil after the controlled cooling to a bundling machine for bundling, wherein the bundling temperature is less than 100 ℃, and the bundling pressure is 10-15 tons by adopting a steel belt bundling machine.
2. The controlled rolling and cooling method for large coils of high carbon alloy tool steel without annealing according to claim 1, wherein: the main chemical composition range of the large coil of the high-carbon alloy tool steel without annealing is C:0.69 to 0.75 percent, si:1.40 to 1.60 percent, mn:0.50 to 0.70 percent, cr:1.00 to 1.20 percent of Ni, 0.10 to 0.20 percent of V, 0.15 to 0.20 percent of V, 0.015 to 0.030 percent of Al, less than or equal to 0.025 percent of P, less than or equal to 0.025 percent of S, less than or equal to 0.20 percent of Cu, and the balance of iron and unavoidable impurities.
3. The use of the large coil of high-carbon alloy tool steel without annealing according to any one of claims 1 to 2, wherein the metallographic structure of the large coil of high-carbon alloy tool steel without annealing is pearlite, the depth of decarburized layer is less than or equal to 0.10mm, and the processing application of drawing hexagonal steel wires without annealing and cold bending forming is realized.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310939742.XA CN117139378A (en) | 2023-07-28 | 2023-07-28 | Controlled rolling and cooling process for large coil of high-carbon alloy tool steel without annealing |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202310939742.XA CN117139378A (en) | 2023-07-28 | 2023-07-28 | Controlled rolling and cooling process for large coil of high-carbon alloy tool steel without annealing |
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| CN117139378A true CN117139378A (en) | 2023-12-01 |
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