CN117463770A - 20CrMnTi steel and rolling method thereof - Google Patents
20CrMnTi steel and rolling method thereof Download PDFInfo
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- CN117463770A CN117463770A CN202311583518.8A CN202311583518A CN117463770A CN 117463770 A CN117463770 A CN 117463770A CN 202311583518 A CN202311583518 A CN 202311583518A CN 117463770 A CN117463770 A CN 117463770A
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- 238000005096 rolling process Methods 0.000 title claims abstract description 178
- 238000000034 method Methods 0.000 title claims abstract description 86
- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 82
- 239000010959 steel Substances 0.000 title claims abstract description 82
- 238000001816 cooling Methods 0.000 claims abstract description 171
- 238000010438 heat treatment Methods 0.000 claims abstract description 92
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 65
- 230000008569 process Effects 0.000 claims abstract description 29
- 238000002791 soaking Methods 0.000 claims abstract description 22
- 238000004513 sizing Methods 0.000 claims abstract description 20
- 238000009749 continuous casting Methods 0.000 claims description 13
- 239000002994 raw material Substances 0.000 claims description 9
- 239000012535 impurity Substances 0.000 claims description 5
- 229910052802 copper Inorganic materials 0.000 claims description 4
- 239000011159 matrix material Substances 0.000 claims description 4
- 229910052759 nickel Inorganic materials 0.000 claims description 4
- 238000007730 finishing process Methods 0.000 claims description 3
- 238000004321 preservation Methods 0.000 abstract description 23
- 238000012545 processing Methods 0.000 abstract description 7
- 239000007769 metal material Substances 0.000 abstract description 2
- 230000000052 comparative effect Effects 0.000 description 9
- 239000000463 material Substances 0.000 description 7
- 238000010586 diagram Methods 0.000 description 6
- 238000010008 shearing Methods 0.000 description 6
- 239000000243 solution Substances 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 3
- 238000012360 testing method Methods 0.000 description 3
- 229910000859 α-Fe Inorganic materials 0.000 description 3
- 229910001566 austenite Inorganic materials 0.000 description 2
- 229910001563 bainite Inorganic materials 0.000 description 2
- 239000013078 crystal Substances 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- 238000001556 precipitation Methods 0.000 description 2
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 210000001787 dendrite Anatomy 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000004744 fabric Substances 0.000 description 1
- 238000005098 hot rolling Methods 0.000 description 1
- 230000002401 inhibitory effect Effects 0.000 description 1
- 229910000734 martensite Inorganic materials 0.000 description 1
- 230000009347 mechanical transmission Effects 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 238000005272 metallurgy Methods 0.000 description 1
- 238000013508 migration Methods 0.000 description 1
- 230000005012 migration Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 229910001562 pearlite Inorganic materials 0.000 description 1
- 238000011056 performance test Methods 0.000 description 1
- 238000010791 quenching Methods 0.000 description 1
- 230000000171 quenching effect Effects 0.000 description 1
- 238000005204 segregation Methods 0.000 description 1
- 239000006104 solid solution Substances 0.000 description 1
- 238000007711 solidification Methods 0.000 description 1
- 230000008023 solidification Effects 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 238000007725 thermal activation Methods 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
- B21B1/00—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations
- B21B1/16—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling wire rods, bars, merchant bars, rounds wire or material of like small cross-section
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B3/00—Rolling materials of special alloys so far as the composition of the alloy requires or permits special rolling methods or sequences ; Rolling of aluminium, copper, zinc or other non-ferrous metals
- B21B3/02—Rolling special iron alloys, e.g. stainless steel
-
- 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
- B21B37/74—Temperature control, e.g. by cooling or heating the rolls or 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
- B21B45/0209—Cooling devices, e.g. using gaseous coolants
- B21B45/0215—Cooling devices, e.g. using gaseous coolants using liquid coolants, e.g. for sections, for tubes
- B21B45/0224—Cooling devices, e.g. using gaseous coolants using liquid coolants, e.g. for sections, for tubes for wire, rods, rounds, bars
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Metal Rolling (AREA)
Abstract
The invention relates to the technical field of metal material deformation heat treatment, in particular to 20CrMnTi steel and a rolling method thereof, wherein the rolling method sequentially comprises the following steps: heating, rough rolling, middle rolling, reducing sizing mill finishing, water cooling, and cooling by a cooling bed; wherein, in the heating procedure, the heat preservation temperature of the soaking section is 1200-1240 ℃; in the rough rolling process, the initial rolling temperature is 1130-1170 ℃; in the finish rolling process of the reducing sizing mill, the finishing temperature is 880-920 ℃; in the cooling process of the cooling bed, the cooling rate is controlled to be 90-150 ℃/min. According to the invention, the 20CrMnTi steel with excellent performance, the strip structure of which is less than or equal to 1.5 level and the intrinsic grain size of which is more than or equal to 7.5 level, is obtained by controlling the final rolling temperature and the cooling rate after rolling, so that the subsequent processing is facilitated.
Description
Technical Field
The invention relates to the technical field of metal material deformation heat treatment, in particular to 20CrMnTi steel and a rolling method thereof.
Background
The gear is one of important parts of mechanical transmission, has wide application in the fields of automobiles, ships, metallurgy, aviation and the like, and particularly in recent years, along with the vigorous development of the automobile industry, the scale of the gear industry in China is continuously expanded, and the continuous requirement of gear steel is driven.
20CrMnTi is one of the most commonly used gear steels, and comprises the following main chemical components in percentage by mass: c:0.17 to 0.23 percent of Si:0.17 to 0.37 percent of Mn:0.8 to 1.1 percent of P: less than or equal to 0.025 percent, S: less than or equal to 0.02 percent, cr:1 to 1.3 percent of Ni: less than or equal to 0.30 percent, less than or equal to 0.30 percent of Cu, 0.04 to 0.10 percent of Ti, and the balance of matrix Fe and unavoidable impurities. The method has the advantages of fine grains, mature and stable heat treatment process, low price and the like, and is widely applied to the automobile industry. However, ti is easy to form large-particle and angular TiN in steel, and a fatigue crack source is formed in use to influence the service life of the gear, and meanwhile, the mixed crystal structure also can influence the heat treatment distortion degree of the gear, so that the intrinsic grain size of the common gear steel is more than or equal to 6 grades; the strip structure of the gear steel can damage the uniformity of a carburized layer, the deformation after quenching is increased, and the gear precision and the meshing degree are reduced, so that the strip structure is strictly controlled, and the control requirement on the strip structure of the high-precision automobile gear steel is less than or equal to 2 levels.
The 20CrMnTi round steel which is commonly produced in the current industry is rolled at high temperature and air-cooled, the band-shaped structure is generally between 2-3 levels (shown in figure 1 a), a small amount of mixed crystal structure is easy to generate on the near surface (shown in figure 1 b), and the service life of the gear is influenced. Therefore, a novel rolling method for controlling the strip grade and the intrinsic grain size of the 20CrMnTi rolled round steel is researched, and has important significance for realizing the green sustainable development of the gear steel industry.
Disclosure of Invention
Aiming at the defects in the prior art, the invention aims to provide 20CrMnTi steel and a rolling method thereof, and the 20CrMnTi steel with excellent performance, the strip structure of which is less than or equal to 1.5 grade and the intrinsic grain size of which is more than or equal to 7.5 grade is obtained by controlling the final rolling temperature and the cooling rate after rolling, so that the subsequent processing is convenient.
In order to achieve the above purpose, the present invention adopts the following technical scheme:
in a first aspect, the invention provides a rolling method of 20CrMnTi steel, which takes a 20CrMnTi continuous casting blank as a raw material, and sequentially comprises the following steps: heating, rough rolling, middle rolling, reducing sizing mill finishing, water cooling, cooling by cooling bed air cooling to obtain the bar;
wherein in the heating procedure, the heating is divided into four sections of heating, namely a preheating section, a first heating section, a second heating section and a soaking section, and the soaking temperature of the soaking section is 1200-1240 ℃;
in the rough rolling process, the initial rolling temperature is 1130-1170 ℃;
in the finish rolling process of the reducing sizing mill, the finishing temperature is 880-920 ℃;
in the cooling process of the cooling bed, the cooling rate is controlled to be 90-150 ℃/min.
According to the invention, the 20CrMnTi steel with excellent performance, the strip structure of which is less than or equal to 1.5 level and the intrinsic grain size of which is more than or equal to 7.5 level, is obtained by controlling the final rolling temperature and the cooling rate after rolling, so that the subsequent processing is facilitated.
Further, in the heating step, the heat preservation time of the soaking section is 60-90 min.
Further, in the heating process, the temperature of the preheating section is 700-800 ℃, the temperature of the first heating section is 1140-1200 ℃, and the temperature of the second heating section is 1200-1240 ℃.
Further, in the heating process, the total heating time in the heating process is 240-360min.
Further, in the intermediate rolling process, the inlet temperature is 950-1000 ℃.
Further, in the reducing mill finishing process, the inlet temperature is 885-925 ℃.
Further, in the cooling bed air cooling step, the upper cooling bed temperature is 760 to 800 ℃.
In the water passing cooling process, water is passed through a water tank, the bar obtained after finish rolling is cooled to 760-800 ℃, the water quantity of the water tank is 100-320L/min, and the water pressure is 5-8 Mpa.
Further, in the cooling bed air cooling process, 1-2 movable teeth are arranged between two adjacent bars at intervals so as to control the cooling rate to be 90-150 ℃/min.
Further, in the cooling process, the temperature of the cooling bed is not more than 600 ℃.
Further, the continuous casting blank comprises the following elements in percentage by mass: c:0.17 to 0.23 percent of Si:0.17 to 0.37 percent of Mn:0.8 to 1.1 percent of P: less than or equal to 0.025 percent, S: less than or equal to 0.02 percent, cr:1 to 1.3 percent of Ni: less than or equal to 0.30 percent, less than or equal to 0.30 percent of Cu, 0.04 to 0.10 percent of Ti, and the balance of matrix Fe and unavoidable impurities.
Further, the specification of the finished bar is 20-60 mm.
In a second aspect, the present invention provides a 20CrMnTi steel made by the rolling method of the 20CrMnTi steel of the first aspect.
Furthermore, the ribbon structure of the 20CrMnTi steel is less than or equal to 1.5 level, and the intrinsic grain size is more than or equal to 7.5 level.
Compared with the prior art, the invention has the beneficial effects that at least:
according to the invention, the 20CrMnTi steel with excellent performance, the strip structure of which is less than or equal to 1.5 level and the intrinsic grain size of which is more than or equal to 7.5 level, is obtained by controlling the final rolling temperature and the cooling rate after rolling, so that the subsequent processing is facilitated.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are needed in the description of the embodiments or the prior art will be briefly described, and it is obvious that the drawings in the description below are some embodiments of the present invention, and other drawings can be obtained according to the drawings without inventive effort for a person skilled in the art.
FIG. 1 is a ribbon structure and an essential grain size diagram of 20CrMnTi steel obtained by adopting a conventional rolling process, wherein FIG. 1a is a ribbon structure diagram of 20CrMnTi steel obtained by adopting a conventional rolling process, and FIG. 1b is an essential grain size diagram of 20CrMnTi steel obtained by adopting a conventional rolling process;
FIG. 2 is a strip chart of a 20CrMnTi steel rolled in example 3 of the present invention, wherein FIG. 2a is a surface strip chart of the 20CrMnTi steel, and FIG. 2b is a core strip chart of the 20CrMnTi steel;
fig. 3 is an essential grain size diagram of 20CrMnTi steel rolled in example 3 of the present invention, wherein fig. 3a is a surface essential grain size diagram of 20CrMnTi steel and fig. 3b is a core essential grain size diagram of 20CrMnTi steel.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions in the embodiments of the present invention will be clearly and completely described in the following in conjunction with the embodiments of the present invention. It will be apparent to those skilled in the art that the examples are merely to aid in understanding the invention and are not to be construed as a specific limitation thereof. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention. The process parameters for the specific conditions not noted in the examples below are generally as usual.
The endpoints of the ranges and any values disclosed in the present invention are not limited to the precise range or value, and the range or value should be understood to include values close to the range or value. For numerical ranges, one or more new numerical ranges may be obtained in combination with each other between the endpoints of each range, between the endpoint of each range and the individual point value, and between the individual point values, and are to be considered as specifically disclosed in the present invention.
In a first aspect, the invention provides a rolling method of 20CrMnTi steel, which takes a 20CrMnTi continuous casting blank as a raw material, and sequentially comprises the following steps: heating, rough rolling, middle rolling, reducing sizing mill finishing, water cooling, cooling by cooling bed air cooling to obtain the bar;
the heating process comprises four sections of heating, namely a preheating section, a first heating section, a second heating section and a soaking section, wherein the soaking section has a heat preservation temperature of 1200-1240 ℃ (for example, the soaking temperature can be 1200 ℃, 1210 ℃, 1220 ℃, 1230 ℃ or 1240 ℃, alN can not be fully dissolved to influence the essential grain size of the bar if the soaking temperature is too low, and the surface burning loss is too heavy and the surface quality of the bar is poor if the soaking temperature is too high;
in the rough rolling step, the initial rolling temperature is 1130 to 1170 ℃ (for example, 1130 ℃, 1150 ℃, 1170 ℃ or the like);
in the finishing step of the reducing sizing mill, the finishing temperature is 880-920 ℃ (for example, 880 ℃, 900 ℃ or 920 ℃ and the like, if the finishing temperature is too high, the bainite content after rolling is too high, the cooling deformation is large, the material hardness is too high, the processing is difficult during the use, and if the finishing temperature is too low, the AlN precipitation effect is poor, and the intrinsic grain size is affected);
in the cooling bed air cooling process, the cooling rate is controlled to be 90-150 ℃/min (for example, 90 ℃/min, 100 ℃/min, 110 ℃/min, 130 ℃/min or 150 ℃/min, if the cooling rate is too high, the bainite content of the bar is too high, even a martensitic structure is generated, the cooling deformation is large, the material hardness is too high, the processing is difficult when the material is used, and if the cooling rate is too low, the banded structure is aggravated.
According to the invention, the strip-shaped structure and grain size of the rolled bar are controlled by controlling the final rolling temperature and the cooling rate after rolling, and 20CrMnTi steel with the strip-shaped structure less than or equal to 1.5 level and the intrinsic grain size more than or equal to 7.5 level and excellent performance can be obtained without heat treatment such as normalizing, so that the production flow is reduced, the energy is saved, the production efficiency is improved, the production cost is reduced, and the subsequent processing is convenient.
In the above rolling method of 20CrMnTi steel, as an alternative embodiment, in the heating step, the soaking time of the soaking section is 60 to 90min (for example, 60min, 70min, 80min or 90 min).
In the above-mentioned rolling method of 20CrMnTi steel, as an alternative embodiment, in the heating step, the temperature of the preheating stage is 700 to 800 ℃ (for example, 700 ℃, 720 ℃, 740 ℃, 760 ℃, 780 ℃ or 800 ℃), the temperature of the heating stage is 1140 to 1200 ℃, and the temperature of the heating stage is 1200 to 1240 ℃.
In the rolling method of 20CrMnTi steel, as an optional implementation manner, in the heating step, the total heating time in the heating step is 240-360min (for example, 240min, 260min, 280min, 300min, 320min, 340min or 360min may be used).
In the above-mentioned rolling method of 20CrMnTi steel, as an alternative embodiment, in the intermediate rolling process, the inlet temperature is 950 to 1000 ℃.
In the above-mentioned rolling method of 20CrMnTi steel, as an alternative embodiment, in the reducing mill finishing process, the inlet temperature is 885 to 925 ℃.
In the above-mentioned rolling method of 20CrMnTi steel, as an alternative embodiment, in the cooling-bed air cooling step, the upper cooling bed temperature is 760 to 800 ℃ (for example, 760 ℃, 780 ℃, 800 ℃ may be used), if the temperature is too high, the strip-like structure is emphasized, if the temperature is too low, the cooling deformation is large, and if the material hardness is too high, the working is difficult.
In the above rolling method of 20CrMnTi steel, as an alternative embodiment, in the water passing cooling step, water passing through a water tank is used to cool the bar obtained after finish rolling to 760-800 ℃, the water amount of the water tank is 100-320L/min (for example, may be 100L/min, 200L/min, 300L/min), and the water pressure is 5-8 Mpa. In the rolling method of 20CrMnTi steel, as an optional implementation manner, in the cooling bed air cooling process, 1-2 movable teeth are spaced between two adjacent bars, so as to control the cooling rate to be 90-150 ℃/min.
In the above-mentioned rolling method of 20CrMnTi steel, as an alternative embodiment, in the cooling-bed air cooling process, the cooling-bed outlet temperature is not more than 600 ℃.
In the rolling method of 20CrMnTi steel, as an optional implementation manner, the mass percentages of the elements in the continuous casting blank are as follows: c:0.17 to 0.23 percent of Si:0.17 to 0.37 percent of Mn:0.8 to 1.1 percent of P: less than or equal to 0.025 percent, S: less than or equal to 0.02 percent, cr:1 to 1.3 percent of Ni: less than or equal to 0.30 percent, less than or equal to 0.30 percent of Cu, 0.04 to 0.10 percent of Ti, and the balance of matrix Fe and unavoidable impurities.
In the rolling method of 20CrMnTi steel, as an alternative embodiment, the specification of the finished bar is 20-60 mm.
The invention designs a rolling process for controlling the banded structure and grain size by utilizing a rolling control and cooling control mechanism and combining the characteristics of 20CrMnTi gear steel, and has the following characteristics compared with the prior art:
(1) The gear steel 20CrMnTi rolling process of the invention is heated at 1220+/-20 ℃ for 60-90 min, so as to ensure that AlN is fully dissolved in the heating process; controlling the final rolling temperature and the upper cooling bed temperature by using a rolling line along a water tank to promote AlN to be dispersed and separated out; distributing materials by using each bar material after rolling at intervals of 1-2 movable teeth, and inhibiting the generation of proeutectoid ferrite to prevent the generation of secondary bands; the technology can accurately control the temperature condition of each key point to obtain the required round bar, and has the characteristic of high control degree;
(2) According to the invention, the final rolling temperature and the upper cooling bed temperature are controlled, the cooling speed after rolling is controlled by using the cloth, the hot rolling state ribbon structure of the obtained gear steel bar is less than or equal to 1.5 level, the intrinsic grain size is more than or equal to 7.5 level, the delivery requirement is met, and heat treatment modes such as normalizing and the like are not needed.
The strip-shaped tissue comprises a primary strip-shaped tissue and a secondary strip-shaped tissue, wherein the primary strip-shaped tissue is an original strip-shaped tissue and is caused by dendrite segregation generated in the pouring and solidification process of the steel ingot; the secondary band structure is a band structure in which a eutectoid band and a pearlite band, which are generated in the rolling direction after rolling, are stacked on each other on the basis of the primary band structure. In the application, the primary banded tissue is improved by high-temperature diffusion, and the heat preservation temperature is not less than 1200 ℃; the secondary banded structure suppresses Ar3 temperature difference of a solute-depleted zone and suppresses proeutectoid ferrite generation by controlling the finishing temperature and the cooling speed after rolling, so as to achieve the effect of improving banded, the finishing temperature is 880-920 ℃, water is cooled through after rolling, proeutectoid ferrite generation is suppressed, 760-800 ℃ is selected after passing water, each bar is distributed at 1-2 moving teeth at intervals during cooling by a cooling bed, the cooling speed after rolling is improved, and the secondary banded structure is prevented from being generated.
The intrinsic grain size affects the toughness and heat treatment distortion degree of the gear, and is an important parameter of gear steel. Austenitic grain growth is a thermal activation process associated with interfacial energy and consists essentially of two parts: firstly, austenite grain boundary migration reduces the grain boundary area, which is the driving force for grain growth; secondly, the AlN particles distributed in a dispersing way play a role in pinning grain boundaries and prevent austenite grains from growing. The control gear steel has the advantages that the intrinsic grain size is mainly controlled by controlling the solid solution and precipitation of AlN, so that the AlN is dispersed and uniformly distributed in the material as much as possible, and therefore, the heating still needs to be not less than 1200 ℃ to ensure that the AlN is fully solid-dissolved in the heating process, finish rolling is carried out at 880-920 ℃, and then the AlN is dispersed and precipitated in the cooling process.
In a second aspect, the present invention provides a 20CrMnTi steel made by the rolling method of the 20CrMnTi steel of the first aspect.
In the 20CrMnTi steel, the band structure of the 20CrMnTi steel is less than or equal to 1.5 level, and the intrinsic grain size is more than or equal to 7.5 level.
The present invention will be described in further detail with reference to specific examples and comparative examples.
The mass percentages of the respective elemental components in the 20CrMnTi continuous cast slab used in the following examples are shown in table 1.
TABLE 1 mass percent of each element component (balance Fe and unavoidable impurities) in 20CrMnTi continuous casting blank
| Element(s) | C | Si | Mn | P | S | Cr | Ni | Cu | Ti |
| Mass percent | 0.19 | 0.26 | 0.88 | 0.015 | 0.015 | 1.05 | 0.05 | 0.05 | 0.055 |
Example 1
A rolling method of 20CrMnTi steel comprises the following steps:
s1, heating process: heating a 20CrMnTi continuous casting blank serving as a raw material in a step-by-step heating furnace, wherein the temperature of a preheating section is 755 ℃, the temperature of a heating section is 1150 ℃, the temperature of a heating section is 1210 ℃, the temperature of a soaking section is 1225 ℃, the heat preservation time is 65min, and the total heating time in a heating process is 280min.
S2, rough rolling procedure: and (5) feeding the heated steel billet into 480 full-continuous two-roll mills for rough rolling, and obtaining a rough rolled piece after 6-pass deformation, wherein the initial rolling temperature is 1158 ℃.
S3, middle rolling procedure: and (3) feeding the rough rolled piece obtained in the step (S2) into a 464+450+350 full-continuous two-roll mill for intermediate rolling, and respectively deforming the rough rolled piece in 4, 6 and 2 passes to obtain the intermediate rolled piece with the specification of 27mm, wherein the intermediate rolling inlet temperature is 975 ℃.
S4, a reducing sizing mill finish rolling process: and (3) rolling the rolled piece with the specification of 27mm after the intermediate rolling by a conveying roller way into a reducing sizing mill, and obtaining a bar with the specification of 20mm after 4-pass deformation, wherein the finish rolling inlet temperature is 898 ℃ and the finish rolling temperature is 895 ℃.
S5, a water cooling process: after finish rolling, the bar is cooled to 770 ℃ by using 1 combined water tank, the temperature of a cooling bed on the bar is controlled by controlling the water quantity of the water tank, the bar with the specification of 20mm obtained after finish rolling is cooled to 770 ℃, the water quantity of the water tank is 215L/min, and the water pressure is 6.5Mpa.
S6, cooling by a cooling bed: and (3) air cooling the bars with the specification of 20mm obtained after finish rolling on a cooling bed (cooling in air), and then shearing, collecting and bundling to obtain finished bars, wherein the temperature of the upper cooling bed is 770 ℃, 1 moving tooth is arranged between each bar in the air cooling process of the cooling bed (1 moving tooth is arranged between two adjacent bars) to control the cooling rate to be 115-150 ℃/min, the temperature of the cooling bed is 400 ℃, and a cooling bed heat preservation cover is not covered in the cooling process.
Example 2
A rolling method of 20CrMnTi steel comprises the following steps:
s1, heating process: heating a 20CrMnTi continuous casting blank serving as a raw material in a step-by-step heating furnace, wherein the temperature of a preheating section is 762 ℃, the temperature of a heating section is 1148 ℃, the temperature of a heating section is 1206 ℃, the heat preservation temperature of a soaking section is 1215 ℃, the heat preservation time is 68min, and the total heating time in a heating process is 290min.
S2, rough rolling procedure: and (5) feeding the heated steel billet into 480 full-continuous two-roll mills for rough rolling, and obtaining a rough rolled piece after 6-pass deformation, wherein the initial rolling temperature is 1155 ℃.
S3, middle rolling procedure: and (3) feeding the rough rolled piece obtained in the step (S2) into a 464+450 full-continuous two-roll mill for intermediate rolling, and respectively deforming for 4 times and 6 times to obtain the intermediate rolled piece with the specification of 35mm, wherein the intermediate rolling inlet temperature is 977 ℃.
S4, a reducing sizing mill finish rolling process: and (3) rolling the rolled piece with the specification of 35mm obtained after the middle rolling by a conveying roller way into a reducing sizing mill, and obtaining a bar with the specification of 30mm after 4-pass deformation, wherein the finish rolling inlet temperature is 903 ℃ and the finish rolling temperature is 900 ℃.
S5, a water cooling process: after finish rolling, the bar is cooled to 775 ℃ by using 1 combined water tank to carry out water cooling, the temperature of a cooling bed on the bar is controlled by controlling the water quantity of the water tank, the bar with the specification of 30mm obtained after finish rolling is cooled to 775 ℃, the water quantity of the water tank is 235L/min, and the water pressure is 6.5Mpa.
S6, cooling by a cooling bed: and (3) air cooling the bars with the specification of 30mm obtained after finish rolling on a cooling bed (cooling in air), and then shearing, collecting and bundling to obtain finished bars, wherein the upper cooling bed temperature is 775 ℃, 1 moving tooth is arranged between each bar in the interval of 1 moving tooth between every two adjacent bars during cooling and air cooling of the cooling bed to control the cooling rate to be 110-145 ℃/min, a cooling bed heat preservation cover is not covered in the cooling process, and the cooling bed temperature is 500 ℃.
Example 3
A rolling method of 20CrMnTi steel comprises the following steps:
s1, heating process: heating a 20CrMnTi continuous casting blank serving as a raw material in a step-by-step heating furnace, wherein the temperature of a preheating section is 763 ℃, the temperature of a heating section is 1161 ℃, the temperature of a heating section is 1212 ℃, the heat preservation temperature of a soaking section is 1218 ℃, the heat preservation time is 72min, and the total heating time in a heating process is 304min.
S2, rough rolling procedure: and (5) feeding the heated steel billet into 480 full-continuous two-roll mills for rough rolling, and obtaining a rough rolled piece after 6-pass deformation, wherein the initial rolling temperature is 1148 ℃.
S3, middle rolling procedure: and (3) feeding the rough rolled piece obtained in the step (S2) into a 464+450 full-continuous two-roll mill for intermediate rolling, and respectively carrying out 4-pass and 6-pass deformation to obtain the intermediate rolled piece with the specification of 46mm, wherein the intermediate rolling inlet temperature is 968 ℃.
S4, a reducing sizing mill finish rolling process: and (3) rolling the rolled piece with the specification of 46mm after the intermediate rolling by a conveying roller way into a reducing sizing mill, and obtaining a bar with the specification of 40mm after 4-pass deformation, wherein the finish rolling inlet temperature is 910 ℃ and the finish rolling temperature is 906 ℃.
S5, a water cooling process: after finish rolling, the bar is cooled to 778 ℃ by using 1 combined water tank to carry out water cooling, the temperature of a cooling bed on the bar is controlled by controlling the water quantity of the water tank, the bar with the specification of 40mm obtained after finish rolling is cooled to be 778 ℃, the water quantity of the water tank is 265L/min, and the water pressure is 7Mpa.
S6, cooling by a cooling bed: and (3) air cooling the bars with the specification of 40mm obtained after finish rolling on a cooling bed (cooling in air), and then shearing, collecting and bundling to obtain finished bars, wherein the upper cooling bed temperature is 778 ℃, and during cooling on the cooling bed, 1 moving tooth is arranged between every two bars (1 moving tooth is arranged between two adjacent bars) at intervals so as to control the cooling rate to be 100-140 ℃/min, the cooling bed temperature is 450 ℃, and a cooling bed heat preservation cover is not covered in the cooling process.
The surface and core band structures of the finished bar obtained in this example are shown in fig. 2a and 2b, respectively; the surface and core intrinsic grain sizes are shown in fig. 3a and 3b, respectively.
Example 4
A rolling method of 20CrMnTi steel comprises the following steps:
s1, heating process: heating a 20CrMnTi continuous casting blank serving as a raw material in a step-by-step heating furnace, wherein the temperature of a preheating section is 741 ℃, the temperature of a heating section is 1142 ℃, the temperature of a heating section is 1201 ℃, the heat preservation temperature of a soaking section is 1220 ℃, the heat preservation time is 75min, and the total heating time in a heating process is 312min.
S2, rough rolling procedure: and (5) feeding the heated steel billet into 480 full-continuous two-roll mills for rough rolling, and obtaining a rough rolled piece after 6-pass deformation, wherein the initial rolling temperature is 1145 ℃.
S3, middle rolling procedure: and (3) feeding the rough rolled piece obtained in the step (S2) into a 464+450 full-continuous two-roll mill for intermediate rolling, and respectively carrying out 4-pass and 4-pass deformation to obtain the intermediate rolled piece with the specification of 60mm, wherein the intermediate rolling inlet temperature is 965 ℃.
S4, a reducing sizing mill finish rolling process: and (3) rolling the rolled piece with the specification of 60mm after the intermediate rolling by a conveying roller way into a reducing sizing mill, and obtaining a bar with the specification of 50mm after 4-pass deformation, wherein the finish rolling inlet temperature is 911 ℃ and the finish rolling temperature is 905 ℃.
S5, a water cooling process: after finish rolling, the bar is cooled to 785 ℃ by using 1 combined water tank to carry out water cooling, the temperature of a cooling bed on the bar is controlled by controlling the water quantity of the water tank, the bar with the specification of 50mm obtained after finish rolling is cooled, the water quantity of the water tank is 280L/min, and the water pressure is 7.5Mpa.
S6, cooling by a cooling bed: and (3) air cooling the bars with the specification of 50mm obtained after finish rolling on a cooling bed (cooling in air), and then shearing, collecting and bundling to obtain finished bars, wherein the upper cooling bed temperature is 785 ℃, 2 moving teeth are arranged between each bar at intervals (2 moving teeth are arranged between two adjacent bars) during cooling on the cooling bed to control the cooling rate to be 95-120 ℃/min, the cooling bed temperature is 300 ℃, and a cooling bed heat preservation cover is not covered during cooling.
Example 5
A rolling method of 20CrMnTi steel comprises the following steps:
s1, heating process: heating a 20CrMnTi continuous casting blank serving as a raw material in a stepping heating furnace, wherein the temperature of a preheating section is 758 ℃, the temperature of a heating section is 1157 ℃, the temperature of a heating section is 1211 ℃, the temperature of a heat preservation section is 1224 ℃, the heat preservation time is 63min, and the total heating time in a heating process is 278min.
S2, rough rolling procedure: and (3) feeding the heated steel billet into 480 full-continuous two-roll mills for rough rolling, and obtaining a rough rolled piece after 6-pass deformation, wherein the initial rolling temperature is 1140 ℃.
S3, middle rolling procedure: and (3) feeding the rough rolled piece obtained in the step (S2) into a 464+450 full-continuous two-roll mill for intermediate rolling, and respectively carrying out 4-pass and 2-pass deformation to obtain the intermediate rolled piece with the specification of 68mm, wherein the intermediate rolling inlet temperature is 960 ℃.
S4, a reducing sizing mill finish rolling process: and (3) rolling the rolled piece with the specification of 68mm obtained after the middle rolling by a conveying roller way into a reducing sizing mill, and obtaining a bar with the specification of 60mm after 4-pass deformation, wherein the finish rolling inlet temperature is 913 ℃ and the finish rolling temperature is 908 ℃.
S5, a water cooling process: and after finish rolling, carrying out through water cooling by using 1 combined water tank, controlling the temperature of a cooling bed on the bar by controlling the water quantity of the water tank, cooling the bar with the specification of 60mm obtained after finish rolling to 790 ℃, wherein the water quantity of the water tank is 310L/min, and the water pressure is 8Mpa.
S6, cooling by a cooling bed: and (3) air cooling the bars with the specification of 60mm obtained after finish rolling on a cooling bed (cooling in air), and then shearing, collecting and bundling to obtain finished bars, wherein the upper cooling bed temperature is 790 ℃, 2 moving teeth are arranged between each bar in an interval manner (2 moving teeth are arranged between two adjacent bars in an interval manner) during cooling on the cooling bed so as to control the cooling rate to be 90-115 ℃/min, the cooling bed temperature is 320 ℃, and a cooling bed heat preservation cover is not covered in the cooling process.
Some specific process parameters of the examples are shown in table 2.
TABLE 2
Comparative example 1
A rolling method of 20CrMnTi steel comprises the following steps:
s1, heating process: heating a 20CrMnTi continuous casting blank serving as a raw material in a step-by-step heating furnace, wherein the temperature of a preheating section is 763 ℃, the temperature of a heating section is 1161 ℃, the temperature of a heating section is 1212 ℃, the heat preservation temperature of a soaking section is 1218 ℃, the heat preservation time is 72min, and the total heating time in a heating process is 304min.
S2, rough rolling procedure: and (5) feeding the heated steel billet into 480 full-continuous two-roll mills for rough rolling, and obtaining a rough rolled piece after 6-pass deformation, wherein the initial rolling temperature is 1148 ℃.
S3, middle rolling procedure: and (3) feeding the rough rolled piece obtained in the step (S2) into a 464+450 full-continuous two-roll mill for intermediate rolling, and respectively carrying out 4-pass and 6-pass deformation to obtain the intermediate rolled piece with the specification of 46mm, wherein the intermediate rolling inlet temperature is 968 ℃.
S4, a reducing sizing mill finish rolling process: and (3) rolling the rolled piece with the specification of 46mm after the intermediate rolling by a conveying roller way into a reducing sizing mill, and obtaining a bar with the specification of 40mm after 4-pass deformation, wherein the finish rolling inlet temperature is 948 ℃ and the finish rolling temperature is 945 ℃.
S5, cooling by a cooling bed: and (3) air cooling the bars with the specification of 40mm obtained after finish rolling on a cooling bed (cooling in air), and then shearing, collecting and bundling to obtain the finished bars, wherein the upper cooling bed temperature is 930 ℃, and 1 moving tooth is arranged between each bar in the air cooling of the cooling bed (1 moving tooth is arranged between two adjacent bars) to control the cooling rate to be 100-140 ℃/min, the cooling bed temperature is 450 ℃, and a cooling bed heat preservation cover is not covered in the cooling process.
Comparative example 2
The rolling method of 20CrMnTi steel provided in this comparative example is substantially the same as that of example 1 except that in step S4, the finish rolling inlet temperature is 805 deg.c and the finish rolling temperature is 800 deg.c.
Comparative example 3
The rolling method of 20CrMnTi steel provided in this comparative example is basically the same as that of example 1 except that the through-water cooling process is not included, and in step S6, the upper cooling bed temperature is 890 ℃.
Comparative example 4
The rolling method of the 20CrMnTi steel provided by the comparative example is basically the same as that of the example 1, and the difference is that in the step S6, bars with the specification of 20mm obtained after finish rolling are slowly cooled to 600 ℃ in a cooling bed heat preservation cover at a cooling speed of 45 ℃/min, then the bars are discharged out of the heat preservation cover to be subjected to cooling bed air cooling (cooled in air), and then sheared, collected and bundled to obtain finished bars, wherein the upper cooling bed temperature is 770 ℃, 1 moving tooth is arranged between each bar in the air cooling of the cooling bed, the distance between every two adjacent bars is 1 moving tooth, and the cooling bed temperature is 400 ℃.
Performance detection
The 20CrMnTi steels obtained in the examples and comparative examples of the present invention were subjected to performance test, wherein the band structure test was performed according to GB/T34474.1, the grain size test was performed according to ISO 643, and the test results are shown in Table 3.
TABLE 3 Table 3
Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present invention, and not for limiting the same; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some or all of the technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit of the invention.
Claims (10)
1. The rolling method of the 20CrMnTi steel is characterized by taking a 20CrMnTi continuous casting blank as a raw material, and sequentially comprises the following steps: heating, rough rolling, middle rolling, reducing sizing mill finishing, water cooling, cooling by cooling bed air cooling to obtain the bar;
wherein in the heating procedure, the heating is divided into four sections of heating, namely a preheating section, a first heating section, a second heating section and a soaking section, and the soaking temperature of the soaking section is 1200-1240 ℃;
in the rough rolling process, the initial rolling temperature is 1130-1170 ℃;
in the finish rolling process of the reducing sizing mill, the finishing temperature is 880-920 ℃;
in the cooling process of the cooling bed, the cooling rate is controlled to be 90-150 ℃/min.
2. The method for rolling 20CrMnTi steel according to claim 1, wherein in the heating step, the soaking time of the soaking section is 60 to 90 minutes;
and/or, in the heating procedure, the temperature of the preheating section is 700-800 ℃, the temperature of the first heating section is 1140-1200 ℃, and the temperature of the second heating section is 1200-1240 ℃;
and/or, in the heating process, the total heating time in the heating process is 240-360min.
3. The rolling method of 20CrMnTi steel according to claim 1, characterized in that in the intermediate rolling process, the inlet temperature is 950-1000 ℃;
and/or in the reducing mill finishing process, the inlet temperature is 885-925 ℃.
4. The method of rolling 20CrMnTi steel according to claim 1, wherein in the cooling bed air cooling step, the upper cooling bed temperature is 760 to 800 ℃.
5. The method for rolling 20CrMnTi steel according to claim 1, wherein in the water passing cooling step, water passing through a water tank is used for cooling the bar obtained after finish rolling to 760-800 ℃, the water amount of the water tank is 100-320L/min, and the water pressure is 5-8 Mpa;
and/or in the cooling bed air cooling process, 1-2 movable teeth are arranged between two adjacent bars at intervals so as to control the cooling rate to be 90-150 ℃/min.
6. The method of rolling 20CrMnTi steel according to claim 1, wherein in the cooling bed air cooling process, the cooling bed temperature is not more than 600 ℃.
7. The rolling method of the 20CrMnTi steel according to claim 1, wherein the mass percentages of the elements in the continuous casting billet are as follows: c:0.17 to 0.23 percent of Si:0.17 to 0.37 percent of Mn:0.8 to 1.1 percent of P: less than or equal to 0.025 percent, S: less than or equal to 0.02 percent, cr:1 to 1.3 percent of Ni: less than or equal to 0.30 percent, less than or equal to 0.30 percent of Cu, 0.04 to 0.10 percent of Ti, and the balance of matrix Fe and unavoidable impurities.
8. The method for rolling 20CrMnTi steel according to claim 1, characterized in that the gauge of the finished bar is 20-60 mm.
9. 20CrMnTi steel, characterized in that it is made by the rolling method of 20CrMnTi steel according to any one of claims 1-8.
10. The 20CrMnTi steel as set forth in claim 9, wherein the 20CrMnTi steel has a band structure of 1.5 or less and a grain size of 7.5 or more.
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