CN117600225A - Non-quenched and tempered steel 38MnVS6 bar and rolling method thereof - Google Patents
Non-quenched and tempered steel 38MnVS6 bar and rolling method thereof Download PDFInfo
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- 238000005096 rolling process Methods 0.000 title claims abstract description 95
- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 40
- 239000010959 steel Substances 0.000 title claims abstract description 40
- 238000000034 method Methods 0.000 title claims abstract description 37
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 50
- 238000001816 cooling Methods 0.000 claims abstract description 39
- 238000004321 preservation Methods 0.000 claims abstract description 33
- 229910000859 α-Fe Inorganic materials 0.000 claims abstract description 33
- 238000010438 heat treatment Methods 0.000 claims abstract description 19
- 238000004513 sizing Methods 0.000 claims abstract description 10
- 238000000137 annealing Methods 0.000 claims abstract description 7
- 230000008569 process Effects 0.000 claims description 7
- 238000002791 soaking Methods 0.000 claims description 6
- 238000004381 surface treatment Methods 0.000 claims description 5
- 238000010008 shearing Methods 0.000 claims description 3
- 239000007769 metal material Substances 0.000 abstract description 2
- 230000009466 transformation Effects 0.000 description 11
- 239000000463 material Substances 0.000 description 10
- 230000001276 controlling effect Effects 0.000 description 8
- 230000000052 comparative effect Effects 0.000 description 6
- 238000004519 manufacturing process Methods 0.000 description 5
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 description 4
- 238000012545 processing Methods 0.000 description 4
- 229910001562 pearlite Inorganic materials 0.000 description 3
- 238000001556 precipitation Methods 0.000 description 3
- 229910045601 alloy Inorganic materials 0.000 description 2
- 239000000956 alloy Substances 0.000 description 2
- 229910001566 austenite Inorganic materials 0.000 description 2
- 238000009749 continuous casting Methods 0.000 description 2
- 238000001514 detection method Methods 0.000 description 2
- 238000004134 energy conservation Methods 0.000 description 2
- 239000012535 impurity Substances 0.000 description 2
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- 230000007246 mechanism Effects 0.000 description 2
- 230000006911 nucleation Effects 0.000 description 2
- 238000010899 nucleation Methods 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 230000006032 tissue transformation Effects 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 229910000954 Medium-carbon steel Inorganic materials 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000005098 hot rolling Methods 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 238000007689 inspection Methods 0.000 description 1
- 238000009413 insulation Methods 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 238000010791 quenching Methods 0.000 description 1
- 230000000171 quenching effect Effects 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 238000010583 slow cooling Methods 0.000 description 1
- 239000007858 starting material Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000005496 tempering Methods 0.000 description 1
- 238000012360 testing method 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
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- 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
- B21B15/0007—Cutting or shearing the product
-
- 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
-
- 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
- B21B45/04—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 de-scaling, e.g. by brushing
- B21B45/08—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 de-scaling, e.g. by brushing hydraulically
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Heat Treatment Of Steel (AREA)
Abstract
The invention belongs to the technical field of metal material deformation heat treatment, and relates to a non-quenched and tempered steel 38MnVS6 bar and a rolling method thereof. Heating, rough rolling, middle rolling, water cooling, reducing sizing and finish rolling, and heat-preserving cooling are sequentially carried out on the steel billet to obtain a hot rolled bar; wherein, the water tanks are distributed along the rolling line, the water tanks are used for water cooling after the middle rolling and before the reducing sizing finish rolling, and the water quantity in the water tanks is controlled to be 150-350L/min, and the water pressure is 6-8 MPa; the heat preservation and cooling are carried out in a cooling bed heat preservation cover, the temperature of the billet entering the heat preservation cover is 760-800 ℃, and the temperature of the billet exiting the heat preservation cover is 570-630 ℃. The obtained bar is free from annealing treatment, the hot-rolled hardness of the bar is 227-238 HBW, and the ferrite proportion is 51.5-54.4%.
Description
Technical Field
The invention belongs to the technical field of metal material deformation heat treatment, and relates to a non-quenched and tempered steel 38MnVS6 bar and a rolling method thereof.
Background
The non-quenched and tempered steel is a steel grade which is added with micro-alloy elements on the basis of the traditional medium carbon steel, and can reach the mechanical property equivalent to that of quenched and tempered steel without a quenching and tempering treatment process after being processed by controlling cooling. Compared with quenched and tempered steel, the non-quenched and tempered steel has the advantages of energy conservation, emission reduction, short production period, low manufacturing cost and the like. With the aggravation of the world energy crisis, in recent years, non-quenched and tempered steel has been rapidly developed, and is widely applied to the automobile industry.
38MnVS6 is a common ferrite-pearlite type non-quenched and tempered steel, and comprises the following main chemical components in percentage by mass: c:0.38 to 0.42 percent of Si:0.50 to 0.70 percent of Mn:1.14 to 1.24 percent of P: less than or equal to 0.02 percent, S:0.028 to 0.042 percent, cr: less than or equal to 0.25 percent, ni: less than or equal to 0.15 percent, cu less than or equal to 0.25 percent, V:0.15 to 0.20 percent, and the balance of matrix Fe and unavoidable impurities. The high-pressure common rail has the advantages of excellent mechanical property, easy cutting and the like, and is widely applied to the production of automobile parts such as crankshafts, high-pressure common rails of engines and the like. But the 38MnVS6 alloy element content is higher, the cooling speed of 38MnVS6 small-size bars (phi 30-phi 60) produced in the industry is faster after rolling, the ferrite content of the material after hot rolling is less, the hardness is higher, and the subsequent blanking and other processing of the material are affected. The part processing factory is used for reducing cutter damage and ensuring production efficiency, and the raw materials are often required to be subjected to annealing treatment and then fed for use, so that the processing cost is increased, and the advantages of energy conservation, emission reduction and environmental protection of the non-quenched and tempered steel are weakened.
The metallographic structure of the 38MnVS6 small-specification bar (phi 30-phi 60) which is commonly produced in the industry at present is shown in the figure 1a and the figure 1b, and the metallographic structure is a ferrite and pearlite structure, wherein the ferrite proportion is 40-45%, and the hardness is 260-275 HBW. When the material is used for producing the high-pressure common rail of the engine in some automobile parts factory, the material is softened and annealed to be between 200 and 248HBW before being used because the hardness of the hot-rolled material is higher, the blanking is difficult, and the cutter damage rate is high.
In order to reduce production cost and carbon emission, the rolling process of 38MnVS6 small-specification bars (phi 30-phi 60) is optimized, so that the ferrite proportion of the rolled material is more than or equal to 50%, the hardness is 200-248 HBW, and the annealing-free delivery is realized.
Disclosure of Invention
The invention aims to provide a non-quenched and tempered steel 38MnVS6 bar and a rolling method thereof, in particular to a rolled bar with the specification of phi 30-phi 60 38MnVS6, and the structure and hardness of the rolled bar are controlled by controlling the rolling temperature and cooling after rolling, so that the subsequent processing is facilitated.
In order to achieve the above purpose, the present invention adopts the following technical scheme:
firstly, a rolling method of a non-quenched and tempered steel 38MnVS6 bar comprises the steps of sequentially heating a billet, rough rolling, middle rolling, water cooling, reducing sizing finish rolling, and heat-preserving cooling to obtain a hot-rolled bar;
wherein, the water tanks are distributed along the rolling line, the water tanks are used for water cooling after the middle rolling and before the reducing sizing finish rolling, and the water quantity in the water tanks is controlled to be 150-350L/min, and the water pressure is 6-8 MPa;
the heat preservation and cooling are carried out in a cooling bed heat preservation cover, the temperature of the billet entering the heat preservation cover is 760-800 ℃, and the temperature of the billet exiting the heat preservation cover is 570-630 ℃.
Further, the soaking temperature of the heating is 1160-1220 ℃, and the heat preservation time is 50-120 min.
Further, the initial rolling temperature of the rough rolling is 1070-1130 ℃.
Further, the finish rolling temperature of the finish rolling is 780-830 ℃.
Further, the finish rolling temperature of the finish rolling is 790 to 820 ℃.
Further, the billet is subjected to surface treatment after heating and before rough rolling.
Still further, the surface treatment includes a high pressure water dephosphorization treatment.
Further, the billet is subjected to shearing, collecting and bundling treatment after being subjected to heat preservation and cooling.
In a second aspect, a non-quenched and tempered steel 38MnVS6 bar, said bar being obtained by the rolling method described above.
Further, the bar is free from annealing treatment, the hot-rolled hardness of the bar is 227-238 HBW, and the ferrite proportion is 51.5-54.4%.
The invention designs a rolling process for controlling the ferrite structure proportion and hardness by using a deformation-induced ferrite phase transformation mechanism and combining the characteristics of 38MnVS6 non-quenched and tempered steel, and has the following beneficial effects compared with the prior art:
(1) According to the 38MnVS6 non-quenched and tempered steel rolling process, the final rolling temperature is controlled to be about 810 ℃ through a rolling line along a water tank, so that the material is deformed at a temperature slightly higher than the Ar3 transformation point, a large amount of dislocation is accumulated to promote ferrite nucleation, the driving force of austenite to ferrite transformation is improved, ferrite precipitation is induced, and the ferrite tissue proportion is increased.
(2) According to the invention, the water tanks are distributed along the line, the final rolling temperature is controlled by controlling the water quantity of the water tanks, and the rolled steel is insulated and slowly cooled by utilizing the cold bed insulation cover.
(3) The 38MnVS6 non-quenched and tempered steel bar rolled by adopting the process has the specification of 30-60 mm, the hot-rolled hardness of 227-238 HBW and the ferrite proportion of 51.5-54.4%, meets the direct blanking requirement of users, and does not need to be treated by adopting heat treatment modes such as softening annealing and the like.
Drawings
FIG. 1 is a 38MnVS6 metallographic structure (1 a. Surface view; 1b core view) under a common rolling process;
FIG. 2 is a 38MnVS6 metallographic structure (2 a. Surface view; 2b core view) of example 2 of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be clearly and completely described in the following in conjunction with the embodiments of the present invention. The embodiments of the present invention are implemented on the premise of the technical solution of the present invention, and detailed embodiments and processes are given, but the scope of the present invention is not limited to the following embodiments, which should be understood by those skilled in the art to help understand the present invention, and should not be construed as being a specific limitation of the present invention. 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 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 the present invention, unless specified and/or indicated otherwise, all numbers referring to amounts of components are "weight or weight ratio" throughout. The process parameters for the specific conditions not noted in the examples below are generally as usual. The starting materials described in the examples below are all commercially available from the public.
A rolling method of a non-quenched and tempered steel 38MnVS6 bar comprises the steps of sequentially heating a steel billet, rough rolling, middle rolling, water cooling, reducing sizing and finish rolling, and heat-preserving and cooling to obtain a hot-rolled bar;
wherein, the rolling line is provided with a water tank along the line, the water tank is used for carrying out water passing cooling after the middle rolling and before the reducing sizing finish rolling, and the water quantity in the water tank is controlled to be 150-350L/min (such as 160L/min, 180L/min, 200L/min, 220L/min, 240L/min, 260L/min, 280L/min, 300L/min, 320L/min and 340L/min), and the water pressure is 6-8 MPa (such as 6.1MPa, 6.3MPa, 6.5MPa, 6.7MPa, 6.9MPa, 7.1MPa, 7.3MPa, 7.5MPa, 7.7MPa and 7.9 MPa);
the heat preservation and cooling are carried out in a cooling bed heat preservation cover, the temperature of the billet entering the heat preservation cover is 760-800 ℃ (such as 765 ℃, 770 ℃, 775 ℃, 780 ℃, 785 ℃, 790 ℃ and 795 ℃), and the temperature of the billet exiting the heat preservation cover is 570-630 ℃ (such as 575 ℃, 580 ℃, 585 ℃, 590 ℃, 595 ℃, 600 ℃, 605 ℃, 610 ℃, 615 ℃, 620 ℃ and 625 ℃).
The invention provides a rolling method of a non-quenched and tempered steel 38MnVS6 bar, which is characterized in that the non-quenched and tempered steel 38MnVS6 bar rolled by the method has the specification of 30-60 mm, hot-rolled hardness of 227-238 HBW and ferrite proportion of 51.5-54.4%, meets the direct blanking requirement of users, and does not need to be treated by adopting heat treatment modes such as softening annealing and the like.
As 38MnVS6 belongs to hypoeutectoid steel, ferrite is a first precipitated phase, and for hypoeutectoid steel, the ferrite proportion after rolling can be increased and the hardness of the material can be reduced by deformation-induced ferrite transformation. The deformation-induced ferrite transformation (DIFT) is a phenomenon caused by the increase of free energy and nucleation position of a system due to deformation, is an important theoretical basis of an online structure regulation and control process, accumulates a large number of dislocation at austenite crystal grains, especially grain boundary positions, through lower rolling temperature, and induces ferrite transformation to form nuclei at the grain boundary positions, so that ferrite transformation is induced, the cooling speed after rolling is controlled, and the aim of regulating and controlling metallographic structure and mechanical property is achieved.
The phase transformation point of the Ar3 of the 38MnVS6 non-quenched and tempered steel is 784 ℃, the phase transformation point of the Ar1 is 733 ℃, and the finishing temperature is about 810 ℃ (slightly higher than the Ar3 temperature) for improving the deformation-induced phase transformation capacity and increasing the ferrite precipitation amount; in order to ensure the ferrite precipitation environment, after rolling, a heat preservation cover is adopted for slow cooling, the temperature of the heat preservation cover is controlled to be 780 ℃ or so, and the temperature of the heat preservation cover is controlled to be 600 ℃ or so, so that the heat preservation cover completes the tissue transformation. The invention controls the final rolling temperature by controlling the water quantity of the water tank, and uses the cooling bed heat preservation cover to preserve heat and slowly cool rolled steel, and the technology can precisely control the temperature conditions of all key points so as to obtain the required round bar, and has the characteristic of high controllable degree.
In addition, when the heat-insulating cover is used for heat-insulating cooling, pit cooling can replace heat-insulating cover cooling to achieve the required tissue hardness, but the pit cooling is complex in operation and high in labor intensity, and the heat-insulating cover is simpler and more convenient to use.
As an alternative embodiment of the rolling method of the present invention, the soaking temperature of the heating is 1160-1220 ℃ (e.g. 1165 ℃, 1170 ℃, 1175 ℃, 1180 ℃, 1185 ℃, 1190 ℃, 1195 ℃, 1200 ℃, 1205 ℃, 1210 ℃, 1215 ℃), and the holding time is 50-120 min (e.g. 60min, 70min, 80min, 90min, 100min, 110 min).
In the above technical solution, the heating may be performed by a heating device such as a stepping furnace. The soaking temperature is controlled to 1160-1220 ℃ during heating, and the soaking heat preservation time is 50-120 min.
As an alternative embodiment of the rolling method of the present invention, the initial rolling temperature of the rough rolling is 1070 to 1130 ℃ (e.g. 1075 ℃, 1080 ℃, 1085 ℃, 1090 ℃, 1095 ℃, 1100 ℃, 1105 ℃, 1110 ℃, 1115 ℃, 1120 ℃, 1125 ℃).
As an alternative embodiment of the rolling method of the present invention, the finish rolling temperature of the finish rolling is 780 to 830 ℃ (e.g., 785 ℃, 790 ℃, 795 ℃, 800 ℃, 805 ℃, 810 ℃, 815 ℃, 820 ℃, 825 ℃), preferably 790 to 820 ℃ (e.g., 791 ℃, 793 ℃, 795 ℃, 797 ℃, 799 ℃, 801 ℃, 803 ℃, 805 ℃, 807 ℃, 809 ℃, 811 ℃, 813 ℃, 815 ℃, 817 ℃ 819 ℃).
As an alternative embodiment of the rolling method according to the invention, the billet is also subjected to a surface treatment, such as a high-pressure water dephosphorization treatment, after heating and before rough rolling. The method aims to remove the iron oxide scale formed on the surface of the billet in the heating process and prevent the iron oxide scale from being pressed in the subsequent rolling process to influence the surface quality of the finished product.
As an alternative implementation mode of the rolling method, the billet is subjected to shearing, collecting and bundling treatment after heat preservation and cooling.
The present invention will be described in further detail with reference to specific examples.
The mass percentages of the respective elemental components in the 38MnVS6 continuous casting billet used in the following examples are shown in table 1, and the balance is Fe and unavoidable impurities.
TABLE 1
| Element(s) | C | Si | Mn | P | S | Cr | Ni | Cu | V |
| Mass percent (%) | 0.39 | 0.57 | 1.2 | 0.015 | 0.035 | 0.2 | 0.1 | 0.05 | 0.16 |
Examples 1 to 4
The rolling process for controlling the ferrite structure proportion and hardness is designed:
1. the process flow comprises the following steps:
38MnVS6 continuous casting blank-step furnace heating-high-pressure water descaling-rough rolling-middle rolling-water cooling-reducing sizing finish rolling-heat preservation cooling-shearing-collecting-bundling
2. Heating soaking temperature: 1190+/-30 ℃ and the heat preservation time is 50-120 min.
3. Start rolling temperature: 1100.+ -. 30 ℃.
4. Finishing temperature: 780-830 ℃.
5. Upper cooling bed temperature: 780.+ -. 20 ℃.
6. Temperature of the heat preservation cover: 600+ -30 DEG C
7. After the middle rolling, a water tank is used, and the final rolling temperature is controlled by controlling the water quantity of the water tank. The water quantity of the water tank is 150-350L/min, and the water pressure is 6-8 MPa.
8. The steel is rapidly conveyed to a cooling bed through a conveying roller way after the steel is subjected to reducing sizing finish rolling, and the temperature of the upper cooling bed is ensured to be near Ar 3; the cooling bed uses the heat preservation cover to carry out heat preservation cooling, reduces the cooling speed after rolling, controls the temperature of the heat preservation cover, and ensures that the steel finishes the tissue transformation in the heat preservation cover.
4 batches of bars (respectively in examples 1-4) with the non-quenched and tempered steel grade of 38MnVS6 are produced according to a designed rolling process, the ferrite structure proportion detection is carried out according to GB/T13298-2015, the Brinell hardness detection is carried out according to GB/T231.1-2018, and the test results are shown in Table 2:
TABLE 2 ferrite proportion and Brinell hardness in bars after Rolling in examples 1 to 4
The final rolling temperature and cooling after rolling are controlled by applying a deformation-induced ferrite transformation mechanism, the ferrite proportion and hardness of the 38MnVS6 non-quenched and tempered steel bar are improved, the hardness of the obtained hot rolled material is 227-238 HBW, the ferrite proportion is 51.5-54.4%, the delivery requirements are met, and heat treatment modes such as softening annealing and the like are not needed to be adopted for treatment.
In example 2, the metallographic structures of the inspection surface and the core are shown in fig. 2a and fig. 2b, respectively, it can be seen that the material surface and the core are both composed of ferrite and pearlite structures, and compared with the conventional rolling process of fig. 1, the ferrite structure proportion of the surface and the core in fig. 2 is improved to a certain extent, the ferrite structure proportion is more than 50% (53.8% in fig. 2a and 54.4% in fig. 2 b), and the grain size of the metallographic structure in fig. 2 is finer than that of the metallographic structure in fig. 1.
Comparative example 1
A rolling method of a non-quenched and tempered steel 38MnVS6 bar is different from example 1 only in that the water quantity of a water tank is 80L/min, the water pressure is 5MPa, and the final rolling temperature is controlled to be 840 ℃. The rest of the settings are the same as in example 1.
Comparative example 2
A rolling method of a non-quenched and tempered steel 38MnVS6 bar is different from example 1 only in that the water quantity of a water tank is 180L/min, the water pressure is 6.5MPa, and the final rolling temperature is controlled to be 780 ℃. The rest of the settings are the same as in example 1.
Comparative example 3
A rolling method of a non-quenched and tempered steel 38MnVS6 bar is different from example 1 only in that the heat-preserving cooling is replaced by air cooling. The rest of the settings are the same as in example 1.
Comparative example 4
A rolling method of a non-quenched and tempered steel 38MnVS6 bar is different from example 1 only in that the temperature of the upper cooling bed is 720 ℃. The rest of the settings are the same as in example 1.
Comparative example 5
A rolling method of a non-quenched and tempered steel 38MnVS6 bar is different from example 1 only in that the temperature of the heat preservation cover is 660 ℃. The rest of the settings are the same as in example 1.
TABLE 3 ferrite proportion and Brinell hardness in rolled bars of comparative examples 1 to 5
The foregoing description of the preferred embodiments of the invention is not intended to limit the invention, but rather to enable any modification, equivalent replacement, improvement or the like to be made within the spirit and principles of the invention, and is within the scope of the appended claims.
Claims (10)
1. A rolling method of a non-quenched and tempered steel 38MnVS6 bar is characterized in that a billet is sequentially heated, rough rolled, middle rolled, water-passing cooled, reduced sizing, finish rolled and heat-preserving cooled to obtain a hot rolled bar;
wherein, the water tanks are distributed along the rolling line, the water tanks are used for water cooling after the middle rolling and before the reducing sizing finish rolling, and the water quantity in the water tanks is controlled to be 150-350L/min, and the water pressure is 6-8 MPa;
the heat preservation and cooling are carried out in a cooling bed heat preservation cover, the temperature of the billet entering the heat preservation cover is 760-800 ℃, and the temperature of the billet exiting the heat preservation cover is 570-630 ℃.
2. The rolling method according to claim 1, wherein the soaking temperature of the heating is 1160-1220 ℃ and the holding time is 50-120 min.
3. The rolling method according to claim 1, wherein the initial rolling temperature of the rough rolling is 1070 to 1130 ℃.
4. The rolling method according to claim 1, wherein the finish rolling has a finishing temperature of 780 to 830 ℃.
5. The rolling method according to claim 4, wherein the finish rolling temperature is 790 to 820 ℃.
6. The rolling method according to claim 1, wherein the billet is further subjected to a surface treatment after heating and before rough rolling.
7. The rolling method according to claim 6, wherein the surface treatment comprises a high-pressure water dephosphorization treatment.
8. The rolling method according to claim 1, wherein the billet is further subjected to shearing, collecting and bundling processes after being cooled at a constant temperature.
9. A non-quenched and tempered steel 38MnVS6 bar, characterized in that said bar is obtained by the rolling method according to any one of claims 1 to 8.
10. The bar according to claim 9, wherein the bar is free of annealing treatment and has a hot rolled hardness of 227-238 HBW and a ferrite ratio of 51.5-54.4%.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202311773046.2A CN117600225A (en) | 2023-12-21 | 2023-12-21 | Non-quenched and tempered steel 38MnVS6 bar and rolling method thereof |
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| CN202311773046.2A CN117600225A (en) | 2023-12-21 | 2023-12-21 | Non-quenched and tempered steel 38MnVS6 bar and rolling method thereof |
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| CN202311773046.2A Pending CN117600225A (en) | 2023-12-21 | 2023-12-21 | Non-quenched and tempered steel 38MnVS6 bar and rolling method thereof |
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