Rolling method of high-carbon free-cutting steel wire
阅读说明：本技术 一种高碳易切削钢线材的轧制方法 (Rolling method of high-carbon free-cutting steel wire ) 是由 徐士新 吕迺冰 王翔 周洁 代锦 刘珂 邱智捷 陈涛 孙齐松 罗洪金 罗志俊 于 2021-08-17 设计创作，主要内容包括：本发明特别涉及一种高碳易切削钢线材的轧制方法,属于钢材轧制技术领域,方法包括：将高碳易切削钢的钢坯进行加热,所述加热包括预热段、加热一段、加热二段和均热段,其中,所述预热段的温度≤750℃,所述加热一段的温度为900℃-1000℃,所述加热二段的温度为1100℃-1200℃,所述均热段的温度为1100℃-1200℃；将加热后的所述钢坯进行除鳞；将除鳞后的所述钢坯进行轧制和吐丝,获得钢丝；将所述钢丝进行风冷；将风冷后的所述钢丝进行集卷,获得高碳易切削钢线材；通过设定较高的加热一段温度和加热二段温度,可快速将铸坯温度提高至能进行碳扩散的温度,减少铸坯因碳偏析造成的局部网状碳化物现象。(The invention particularly relates to a rolling method of a high-carbon free-cutting steel wire rod, belonging to the technical field of steel rolling, and the method comprises the following steps: heating a steel billet of high-carbon free-cutting steel, wherein the heating comprises a preheating section, a first heating section, a second heating section and a soaking section, the temperature of the preheating section is less than or equal to 750 ℃, the temperature of the first heating section is 900-1000 ℃, the temperature of the second heating section is 1100-1200 ℃, and the temperature of the soaking section is 1100-1200 ℃; descaling the heated steel billet; rolling and spinning the descaled steel billet to obtain a steel wire; air-cooling the steel wire; collecting and coiling the steel wire subjected to air cooling to obtain a high-carbon free-cutting steel wire rod; by setting higher first-stage heating temperature and second-stage heating temperature, the temperature of the casting blank can be quickly increased to the temperature capable of performing carbon diffusion, and the phenomenon of local net-shaped carbide of the casting blank caused by carbon segregation is reduced.)
1. A rolling method of a high-carbon free-cutting steel wire rod is characterized by comprising the following steps:
heating a steel billet of high-carbon free-cutting steel, wherein the heating comprises a preheating section, a first heating section, a second heating section and a soaking section, the temperature of the preheating section is less than or equal to 750 ℃, the temperature of the first heating section is 900-1000 ℃, the temperature of the second heating section is 1100-1200 ℃, and the temperature of the soaking section is 1100-1200 ℃;
descaling the heated steel billet;
rolling and spinning the descaled steel billet to obtain a steel wire;
air-cooling the steel wire;
and collecting and coiling the steel wire after air cooling to obtain the high-carbon free-cutting steel wire.
2. The method for rolling a high-carbon free-cutting steel wire rod according to claim 1, wherein a billet of the high-carbon free-cutting steel is heated, the heating comprises a preheating section, a heating section and a soaking section, the temperature difference between the billet head and the billet tail of the billet is less than or equal to 20 ℃, the whole heating time is controlled within 2h-3h, and the proportion of residual oxygen in the heating atmosphere is controlled within 1.0-3.0% by volume fraction.
3. The method for rolling a high-carbon free-cutting steel wire rod according to claim 1, wherein in the descaling of the heated billet, the pressure of the descaling water is not less than 16Mpa, and the billet head of the billet is not descaled.
4. The method for rolling the high-carbon free-cutting steel wire rod according to claim 1, wherein in the rolling and spinning of the descaled steel slab, the rolling start temperature is controlled to be 1050 ℃ to 1150 ℃, the temperature of the slab at the inlet of the finishing mill group is controlled to be 1000 ℃ to 1050 ℃, the temperature of the slab at the inlet of the reducing sizing mill group is controlled to be 950 ℃ to 1000 ℃, and the temperature of the slab after the slab exits the reducing sizing mill group is reduced to 780 ℃ to 830 ℃.
5. The method for rolling a high carbon free-cutting steel wire rod according to claim 1, wherein the steel wire is subjected to air cooling using a stelmor air cooling line.
6. The method for rolling a high-carbon free-cutting steel wire rod according to claim 5, wherein the steel wire is subjected to air cooling, parameters of the stelmor air cooling line are preset according to specifications of the steel wire, the steel wire is cooled to a carbide precipitation region and a high-temperature pearlite region or below, and after entering the sorbite region, a heat-insulating cover is covered to achieve sufficient sorbite of the steel wire.
7. The rolling method of the high carbon free-cutting steel wire rod according to claim 6, wherein the parameters of the stelmor air cooling line comprise a roller table speed parameter, a heat preservation cover opening condition parameter and a fan opening condition parameter;
the corresponding relation between the specification of the steel wire and the speed parameter of the roller way is as follows:
the corresponding relation between the specification of the steel wire and the opening condition parameters of the heat preservation cover is as follows:
The corresponding relation between the specification of the steel wire and the fan starting condition parameters is as follows:
。
8. The method for rolling a high carbon free-cutting steel wire according to claim 1, wherein the steel wire after air-cooling is subjected to the bundling at a temperature of 300 ℃ to 400 ℃.
9. The rolling method of a high carbon free-cutting steel wire rod according to claim 1, wherein the high carbon free-cutting steel includes a sulfur free-cutting steel and a lead free-cutting steel.
10. The rolling method of a high carbon free-cutting steel wire rod according to claim 9, wherein the chemical composition of the sulfur free-cutting steel comprises, in terms of weight fraction: 0.70-1.10% of C, 0-0.5% of Si, 0.50-1.20% of Mn, 0-0.40% of S, 0-0.08% of P, and the balance of Fe and inevitable impurities; the lead-based free-cutting steel comprises the following chemical components: 0.70-1.10% of C, 0-0.5% of Si, 0.50-1.20% of Mn, 0-0.20% of S, 0-0.05% of P, 0.15-0.35% of Pb, and the balance of Fe and inevitable impurities.
Technical Field
The invention belongs to the technical field of steel rolling, and particularly relates to a rolling method of a high-carbon free-cutting steel wire.
Background
In recent years, with the rapid development of the industries of automobiles, communication and precision instruments, the cutting performance of the alloy structural steel is gradually developed and applied, and the free-cutting of the alloy structural steel becomes the development trend of the alloy structural steel and the free-cutting steel in the future. The high-carbon series alloy structural steel needs to take both free-cutting performance and mechanical performance after adding free-cutting elements (S, Pb and the like), particularly the problem of network carbides frequently encountered in the production process of high-carbon steel, and the addition of the free-cutting elements brings brand-new influence on control measures of the high-carbon series alloy structural steel.
In particular, downstream users generally perform multi-pass cold drawing and spheroidizing annealing treatment on high-carbon free-cutting steel wires before using the high-carbon free-cutting steel wires so as to avoid wire breakage caused by net-shaped carbides during drawing, and the drawing process seriously influences the continuous operation rate and increases the production cost. When the grade of the net-shaped carbide in the hot rolled wire rod reaches more than 2.5 grades, the net-shaped carbide can not be completely eliminated by spheroidizing annealing, and the carbide particles after spheroidizing of the net-shaped carbide are far larger than the carbide particles after spheroidizing of pearlite lamellar cementite, so that the carbide particles are not uniform. Therefore, control of the net carbides in the hot rolled wire rod is of great importance.
Generally, the control of the high-carbon steel wire mesh carbide adopts a process of low-temperature rolling and rapid cooling after rolling, so as to prevent the carbide from being precipitated at an austenite crystal boundary to form a mesh structure (particularly at the center of a wire rod) in the process of slow cooling after rolling, and seriously affect the plasticity of the high-carbon steel wire. When the conventional high-carbon steel wire is rolled, the finishing temperature is usually controlled to be less than 900 ℃, and the steel wire is rapidly cooled to 600-700 ℃ after being rolled. For example, in the method for controlling the net-shaped carbide and the ribbon-shaped carbide of the bearing steel and the bearing steel of the Chinese patent application CN105648170B, in order to control the net-shaped carbide of the bearing steel, the finishing temperature is controlled within the range of 830-870 ℃, and then the bearing steel is cooled to 600-650 ℃ within 3-7 s, so that the grade of the net-shaped carbide in the bearing steel is reduced from above 3.0 grade to 2.0 grade or 3.0 grade; in the method for reducing the mesh carbide level of the bridge cable steel, the Chinese patent application CN106065452B is characterized in that the finish rolling inlet temperature reaches 760-800 ℃, and the mesh carbide in the bridge cable steel wire rod is reduced to not more than 0.5 level; in the Chinese patent application CN109680136A high-carbon rolled material and the preparation method and application thereof, in order to relieve the uneven distribution of carbides, the final rolling temperature range is 850-900 ℃, the rolled material is rapidly cooled to 650-700 ℃ after rolling, and the mesh carbide grade of each embodiment is less than or equal to 2.5 grade.
However, when the free cutting elements such as S, Pb are added into the steel, the high-temperature thermoplasticity of the high-carbon steel is obviously changed, as shown in fig. 1, the coverage temperature range of the low-plasticity interval is obviously widened, and the conventional control means of the net-shaped carbide of the high-carbon steel wire is not applicable any more.
In addition, the high sorbite proportion not only enables the high-carbon steel wire to have excellent mechanical property, but also is beneficial to the smooth drawing. The traditional method for improving the sorbite proportion of high-carbon steel is to perform isothermal quenching treatment on an austenitized wire rod in a sorbite phase-change interval, and although the traditional method can greatly improve the sorbite proportion, the traditional method increases the production cost. At present, the high-carbon free-cutting steel wire with high sorbite proportion is produced on line by adopting a high-speed wire production line equipped with a stelmor air-cooling line with certain difficulty.
Disclosure of Invention
In view of the above problems, the present invention has been made to provide a rolling method of a high carbon free-cutting steel wire rod that overcomes or at least partially solves the above problems.
The embodiment of the invention provides a rolling method of a high-carbon free-cutting steel wire rod, which comprises the following steps:
heating a steel billet of high-carbon free-cutting steel, wherein the heating comprises a preheating section, a first heating section, a second heating section and a soaking section, the temperature of the preheating section is less than or equal to 750 ℃, the temperature of the first heating section is 900-1000 ℃, the temperature of the second heating section is 1100-1200 ℃, and the temperature of the soaking section is 1100-1200 ℃;
descaling the heated steel billet;
rolling and spinning the descaled steel billet to obtain a steel wire;
air-cooling the steel wire;
and collecting and coiling the steel wire after air cooling to obtain the high-carbon free-cutting steel wire.
Optionally, a steel billet of the high-carbon free-cutting steel is heated, wherein the heating comprises a preheating section, a first heating section, a second heating section and a soaking section, the temperature difference between the billet head and the billet tail of the steel billet is less than or equal to 20 ℃, the whole heating time is controlled within 2h-3h, and the proportion of residual oxygen in the heating atmosphere is controlled within 1.0-3.0% by volume fraction.
Optionally, in the descaling of the heated steel billet, the pressure of descaling water for descaling is more than or equal to 16Mpa, and the billet head of the steel billet is not subjected to descaling.
Optionally, in the rolling and spinning of the descaled steel billet, the rolling start temperature is controlled to be 1050-1150 ℃, the temperature of the plate blank at the inlet of the finishing mill group is controlled to be 1000-1050 ℃, the temperature of the plate blank entering the reducing sizing mill group is controlled to be 950-1000 ℃, and the temperature of the plate blank after exiting the reducing sizing mill group is reduced to 780-830 ℃.
Optionally, in the air cooling of the steel wire, a stelmor air cooling line is adopted in the air cooling.
Optionally, in the air cooling of the steel wire, parameters of the stelmor air cooling line are preset according to specifications of the steel wire, so that the steel wire is cooled to a carbide precipitation interval and a high-temperature pearlite interval, and after entering a sorbite interval, a heat preservation cover is added to achieve full sorbite of the steel wire.
Optionally, the parameters of the stelmor air cooling line include a roller speed parameter, a heat preservation cover opening condition parameter and a fan opening condition parameter;
the corresponding relation between the specification of the steel wire and the speed parameter of the roller way is as follows:
the corresponding relation between the specification of the steel wire and the opening condition parameters of the heat preservation cover is as follows:
specification/mm
1#-3#
4#-14#
15#
16#-20#
21#-22#
Φ5-Φ12
Opening device
Closing device
Half-open
Closing device
Opening device
Φ12-Φ18
Opening device
Closing device
Half-open
Closing device
Opening device
Φ18-Φ25
Opening device
Closing device
Half-open
Closing device
Opening device
The corresponding relation between the specification of the steel wire and the fan starting condition parameters is as follows:
specification/mm
1#
2#
3#
4#-22#
Φ5-Φ12
25％-30％
10％-15％
0％-5％
Closing device
Φ12-Φ18
30％-35％
15％-20％
5％-10％
Closing device
Φ18-Φ25
35％-40％
20％-25％
10％-15％
Closing device
。
Optionally, during the process of collecting and coiling the steel wire after air cooling, the temperature of the collected and coiled steel wire is 300-400 ℃.
Optionally, the high-carbon free-cutting steel includes sulfur-based free-cutting steel and lead-based free-cutting steel.
Optionally, the sulfur-based free-cutting steel comprises the following chemical components in percentage by weight: 0.70-1.10% of C, 0-0.5% of Si, 0.50-1.20% of Mn, 0-0.40% of S, 0-0.08% of P, and the balance of Fe and inevitable impurities; the lead-based free-cutting steel comprises the following chemical components: 0.70-1.10% of C, 0-0.5% of Si, 0.50-1.20% of Mn, 0-0.20% of S, 0-0.05% of P, 0.15-0.35% of Pb, and the balance of Fe and inevitable impurities.
One or more technical solutions in the embodiments of the present invention have at least the following technical effects or advantages:
the embodiment of the invention provides a rolling method of a high-carbon free-cutting steel wire rod, which comprises the following steps: heating a steel billet of high-carbon free-cutting steel, wherein the heating comprises a preheating section, a first heating section, a second heating section and a soaking section, the temperature of the preheating section is less than or equal to 750 ℃, the temperature of the first heating section is 900-1000 ℃, the temperature of the second heating section is 1100-1200 ℃, and the temperature of the soaking section is 1100-1200 ℃; descaling the heated steel billet; rolling and spinning the descaled steel billet to obtain a steel wire; air-cooling the steel wire; collecting and coiling the steel wire subjected to air cooling to obtain a high-carbon free-cutting steel wire rod; by setting higher first-stage heating temperature and second-stage heating temperature, the temperature of the casting blank can be quickly increased to the temperature capable of performing carbon diffusion, and the phenomenon of local net-shaped carbide of the casting blank caused by carbon segregation is reduced.
The foregoing description is only an overview of the technical solutions of the present invention, and the embodiments of the present invention are described below in order to make the technical means of the present invention more clearly understood and to make the above and other objects, features, and advantages of the present invention more clearly understandable.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on the drawings without creative efforts.
FIG. 1 is a diagram of the high-temperature thermoplastic change of high-carbon steel with free-cutting elements added in the background art;
FIG. 2 is a diagram of the optical metallographic structure of the core of the high-carbon free-cutting steel wire obtained in example 1 of the present invention;
FIG. 3 is a diagram of the optical metallographic structure of the core of the high-carbon free-cutting steel wire obtained in example 2 of the present invention;
FIG. 4 is a diagram of the optical metallographic structure of the core of the high-carbon free-cutting steel wire obtained in example 3 of the present invention;
FIG. 5 is a diagram of the optical metallographic structure of the core of the high-carbon free-cutting steel wire obtained in example 4 of the present invention;
FIG. 6 is a diagram of the optical metallographic structure of the core of the high-carbon free-cutting steel wire obtained in example 5 of the present invention;
FIG. 7 is the core optical metallographic structure of the high carbon free-cutting steel wire obtained in comparative example 2 of the present invention
Fig. 8 is a flow chart of a method provided by an embodiment of the invention.
Detailed Description
The present invention will be described in detail below with reference to specific embodiments and examples, and the advantages and various effects of the present invention will be more clearly apparent therefrom. It will be understood by those skilled in the art that these specific embodiments and examples are for the purpose of illustrating the invention and are not to be construed as limiting the invention.
Throughout the specification, unless otherwise specifically noted, terms used herein should be understood as having meanings as commonly used in the art. Accordingly, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. If there is a conflict, the present specification will control.
Unless otherwise specifically stated, various raw materials, reagents, instruments, equipment and the like used in the present invention are commercially available or can be prepared by existing methods.
In order to solve the technical problems, the general idea of the embodiment of the application is as follows:
according to an exemplary embodiment of the present invention, there is provided a rolling method of a high carbon free-cutting steel wire rod, the method including:
s1, heating a steel billet of high-carbon free-cutting steel, wherein the heating comprises a preheating section, a first heating section, a second heating section and a soaking section, the temperature of the preheating section is less than or equal to 750 ℃, the temperature of the first heating section is 900-1000 ℃, the temperature of the second heating section is 1100-1200 ℃, and the temperature of the soaking section is 1100-1200 ℃;
the high-carbon free-cutting steel comprises sulfur free-cutting steel and lead free-cutting steel; the sulfur-series free-cutting steel comprises the following chemical components in percentage by weight: 0.70-1.10% of C, 0-0.5% of Si, 0.50-1.20% of Mn, 0-0.40% of S, 0-0.08% of P, and the balance of Fe and inevitable impurities; the lead-based free-cutting steel comprises the following chemical components: 0.70-1.10% of C, 0-0.5% of Si, 0.50-1.20% of Mn, 0-0.20% of S, 0-0.05% of P, 0.15-0.35% of Pb, and the balance of Fe and inevitable impurities.
Specifically, a steel billet is put into a furnace for heating, the temperature and time of each section of the heating furnace are strictly controlled, wherein the temperature of a preheating section is less than or equal to 750 ℃, the temperature of a heating section is 900-1000 ℃, the temperature of a heating section is 1100-1200 ℃, the temperature of a soaking section is 1100-1200 ℃, the temperature deviation of the head and the tail of the steel billet is less than or equal to 20 ℃, the total standing time is controlled within 2-3 h, and the residual oxygen ratio (volume percentage) of the atmosphere of the heating furnace is controlled within 1.0-3.0%.
The control idea of heating the conventional high-carbon steel casting blank is as follows: in order to ensure the carbide to be fully dissolved and diffused, the high-temperature section above 1200 ℃ is heated for a long time. The parameter control which is different from the conventional high-carbon steel casting blank heating is that: by setting a higher heating section temperature, the temperature of the casting blank can be quickly increased to a temperature capable of performing carbon diffusion, and the phenomenon of local net-shaped carbide of the casting blank caused by carbon segregation is reduced; the low residual oxygen value of the heating furnace atmosphere and the short furnace standing time are beneficial to reducing the generation of thick iron scale due to long-time high-temperature oxidation, and simultaneously, the low-melting-point eutectic of FeS-FeO (which is difficult to remove by high-pressure water descaling) formed by free-cutting elements such as sulfur and the like and Fe can be reduced, thereby ensuring the surface quality of the hot-rolled product.
S2, descaling the heated steel billet;
specifically, high-pressure water descaling is carried out after the steel plate is taken out of the heating furnace, the descaling water pressure is not less than 16MPa, and high-pressure water delayed spraying is started for 0.5-1.5 s.
By means of delayed spraying of the high-pressure descaling water, the head temperature of the casting blank caused by high-pressure water descaling can be reduced, and the cracking phenomenon caused by entering a low-plasticity area when the head of the free-cutting steel casting blank is bitten in the rolling process is avoided.
S3, rolling and spinning the descaled steel billet to obtain a steel wire;
specifically, a high-temperature rapid rolling process is adopted in the rolling process, the initial rolling temperature is controlled to be 1050-1150 ℃, the inlet temperature of a finishing mill group is controlled to be 1000-1050 ℃, the temperature of the finishing mill group is controlled to be 950-1000 ℃ when the finishing mill group enters the reducing sizing mill group, and the water quantity of a water tank is strictly controlled after the finishing mill group exits from the reducing sizing mill group, so that the spinning temperature is controlled to be 780-830 ℃.
The whole rolling process adopts a high-temperature fast rolling control idea, rolling in a high-temperature low-plasticity interval is avoided, the water quantity of a water tank behind a reducing sizing mill set is set according to the specification of a wire rod through calculation after rolling, ultra-fast cooling is carried out, and stable spinning temperature is realized.
S4, air cooling is carried out on the steel wire;
specifically, a stelmor air cooling line is entered after spinning, a cooling control process is adopted in the cooling process, and the stelmor air cooling line control parameters are different according to the specification and the size of the wire rod, and are specifically shown in tables 1, 2 and 3:
TABLE 1 Stelmo air-cooled line roller speed (m/min)
TABLE 2 Stelmo air-cooled line insulation cover opening situation
Specification/mm
1#～3#
4#～14#
15#
16#～20#
21#～22#
Φ5～Φ12
Opening device
Closing device
Half-open
Closing device
Opening device
Φ12～Φ18
Opening device
Closing device
Half-open
Closing device
Opening device
Φ18～Φ25
Opening device
Closing device
Half-open
Closing device
Opening device
TABLE 3 Stermol air-cooled linear fan turn-on (maximum power and air quantity of 20 km)3/h)
Specification/mm
1#
2#
3#
4#～22#
Φ5～Φ12
25％～30％
10％～15％
0～5％
Closing device
Φ12～Φ18
30％～35％
15％～20％
5％～10％
Closing device
Φ18～Φ25
35％～40％
20％～25％
10％～15％
Closing device
The main technical idea of stelmor air cooling line control is as follows: after spinning, the steel is continuously cooled to a carbide precipitation interval and a high-temperature pearlite interval below by controlling the air quantity of the fan according to the specification of the wire, and a heat-insulating cover is covered after the steel enters a sorbite interval, so that the steel is fully sorbitized to reach 80-95%, the existence of hard phase tissues is reduced, and the method is not only favorable for eliminating reticular carbides, but also favorable for downstream users to draw smoothly.
S5, collecting and coiling the steel wires after air cooling to obtain high-carbon free-cutting steel wires;
specifically, the coil collecting temperature is 300-400 ℃ when the coil is unwound from a stelmor air cooling line, and the coil is cooled to room temperature and packaged.
The rolling method is suitable for rolling the high-carbon free-cutting steel billet with the section size range of (120-300) mmX (120-300) mm.
The invention is suitable for the production of high-carbon free-cutting steel wires with the specification of phi 5 mm-phi 25 mm.
When the high-carbon free-cutting steel adopts the conventional high-carbon steel wire rolling process, the head splitting phenomenon is serious, the rolling is particularly difficult to move smoothly, the surface defect is serious, and the grade of the net carbide of the high-carbon free-cutting steel wire is basically more than 1.5 grade; after the rolling method is adopted, the grade of the high-carbon free-cutting steel wire mesh carbide is effectively controlled to be below 1.0 grade, the sorbite proportion can reach 80-95 percent, the rolling is smooth, the surface defect rate is within 1 percent, and the spheroidizing annealing times of downstream users are correspondingly reduced by 1-2 times along with the reduction of the mesh grade of the hot-rolled wire rod carbide.
The rolling method of the high carbon free-cutting steel wire rod of the present application will be described in detail with reference to examples, comparative examples and experimental data.
Example 1
A rolling method of a high carbon free-cutting steel wire rod, the method comprising:
a high-carbon sulfur-series free-cutting steel casting blank with the section size of 120mm multiplied by 120mm is adopted to produce a wire rod with the specification of phi 5mm, and the wire rod comprises the chemical components (in mass percentage) of 0.70% of C, 0.20% of Si, 1.20% of Mn, 0.02% of P, 0.40% of S, and the balance of Fe and inevitable impurities. The wire rod is rolled into corresponding specification by a high-speed wire rod rolling mill and then is spun and coiled. The specific control parameters of the production process are as follows: the temperature of the preheating section of the steel billet is 700 ℃, the temperature of the heating I section is 900 ℃, the temperature of the heating II section is 1175 ℃, the temperature of the soaking section is 1150 ℃, the temperature deviation of the head and the tail of the steel billet is less than or equal to 20 ℃, the total furnace residence time is controlled to be 3 hours, and the residual oxygen proportion (volume fraction) of the atmosphere of the heating furnace is controlled to be 2.0 percent. Taking the mixture out of the heating furnace for high-pressure water descaling, and starting the high-pressure water spraying for 1.5s in a delayed manner, wherein the descaling water pressure is 18 MPa; the initial rolling temperature is 1150 ℃, the inlet temperature of a finishing mill group is 1050 ℃, the temperature of the finishing mill group is 1000 ℃ and the spinning temperature is 830 ℃; stelmor air-cooled line parameters roller table speed are shown in the following table:
1, 2, 3, 21 and 22 of the heat preservation cover are opened, and the opening condition of the fan is shown in the following table:
1#
2#
3#
4#～22#
25％
10％
closing device
Closing device
。
Example 2
A rolling method of a high carbon free-cutting steel wire rod, the method comprising:
a high-carbon lead-series free-cutting steel casting blank with the section size of 150mm multiplied by 150mm is adopted to produce a wire rod with the specification of phi 9mm, and the wire rod comprises the chemical components (in mass percentage) of C1.10%, Si 0.50%, Mn 0.50%, P0.03%, S0.14%, Pb 0.35%, and the balance of Fe and inevitable impurities. The wire rod is rolled into corresponding specification by a high-speed wire rod rolling mill and then is spun and coiled. The specific control parameters of the production process are as follows: the temperature of the preheating section of the billet is 750 ℃, the temperature of the heating I section is 950 ℃, the temperature of the heating II section is 1175 ℃, the temperature of the soaking section is 1150 ℃, the temperature deviation of the head and the tail of the billet is less than or equal to 20 ℃, the total furnace residence time is controlled to be 2.5 hours, and the residual oxygen proportion (volume fraction) of the atmosphere of the heating furnace is controlled to be 2.5 percent. Taking the mixture out of the heating furnace for high-pressure water descaling, and starting the high-pressure water spraying for 1.5s in a delayed manner, wherein the descaling water pressure is 18 MPa; the initial rolling temperature is 1100 ℃, the inlet temperature of a finishing mill group is 1030 ℃, the temperature of the finishing mill group is 950 ℃, and the spinning temperature is 810 ℃; stelmor air-cooled line parameters roller table speed are shown in the following table:
1, 2, 3, 21 and 22 of the heat preservation cover are opened, and the opening condition of the fan is shown in the following table:
1#
2#
3#
4#～22#
fan on condition
27％
12％
2％
Closing device
。
Example 3
A rolling method of a high carbon free-cutting steel wire rod, the method comprising:
a high-carbon sulfur-series free-cutting steel casting blank with the section size of 200mm multiplied by 200mm is adopted to produce a wire rod with the specification of phi 12mm, and the wire rod comprises the chemical components (in mass percentage) of 0.78% of C, 0.38% of Si, 1.08% of Mn, 0.08% of P, 0.28% of S, and the balance of Fe and inevitable impurities. The wire rod is rolled into corresponding specification by a high-speed wire rod rolling mill and then is spun and coiled. The specific control parameters of the production process are as follows: the temperature of the preheating section of the billet is 750 ℃, the temperature of the heating I section is 950 ℃, the temperature of the heating II section is 1150 ℃, the temperature of the soaking section is 1150 ℃, the temperature deviation of the head and the tail of the billet is less than or equal to 20 ℃, the total furnace residence time is controlled to be 2 hours, and the residual oxygen proportion (volume fraction) of the atmosphere of the heating furnace is controlled to be 2.0 percent. Taking the steel plate out of the heating furnace for high-pressure water descaling, starting the high-pressure water spraying for 1s in a delayed manner, wherein the descaling water pressure is 16 MPa; the initial rolling temperature is 1100 ℃, the inlet temperature of a finishing mill group is 1030 ℃, the temperature of the finishing mill group is 980 ℃, and the spinning temperature is 800 ℃; stelmor air-cooled line parameters roller table speed are shown in the following table:
1, 2, 3, 21 and 22 of the heat preservation cover are opened, and the opening condition of the fan is shown in the following table:
1#
2#
3#
4#～22#
fan on condition
30％
15％
5％
Closing device
。
Example 4
A rolling method of a high carbon free-cutting steel wire rod, the method comprising:
a high-carbon lead-series free-cutting steel casting blank with the section size of 250mm multiplied by 250mm is adopted to produce a wire rod with the specification of phi 18mm, and the wire rod comprises the chemical components (in percentage by mass) of 0.95% of C, 0.15% of Si, 0.75% of Mn, 0.05% of P, 0.15% of S, 0.15% of Pb, and the balance of Fe and inevitable impurities. The wire rod is rolled into corresponding specification by a high-speed wire rod rolling mill and then is spun and coiled. The specific control parameters of the production process are as follows: the temperature of the preheating section of the steel billet is 750 ℃, the temperature of the heating I section is 1000 ℃, the temperature of the heating II section is 1100 ℃, the temperature of the soaking section is 1100 ℃, the temperature deviation of the head and the tail of the steel billet is less than or equal to 20 ℃, the total furnace residence time is controlled to be 3 hours, and the residual oxygen proportion (volume fraction) of the atmosphere of the heating furnace is controlled to be 3.0 percent. Taking the mixture out of the heating furnace for high-pressure water descaling, and starting the high-pressure water spraying in a delayed manner for 0.5s, wherein the descaling water pressure is 20 MPa; the initial rolling temperature is 1050 ℃, the inlet temperature of a finishing mill group is 1000 ℃, the temperature of the finishing mill group is 950 ℃ and the spinning temperature is 780 ℃; stelmor air-cooled line parameters roller table speed are shown in the following table:
1, 2, 3, 21 and 22 of the heat preservation cover are opened, and the opening condition of the fan is shown in the following table:
1#
2#
3#
4#～22#
fan on condition
35％
20％
10％
Closing device
。
Example 5
A rolling method of a high carbon free-cutting steel wire rod, the method comprising:
a high-carbon sulfur-series free-cutting steel casting blank with the section size of 300mm multiplied by 300mm is adopted to produce a wire rod with the specification of phi 25mm, and the wire rod comprises the chemical components (in mass percentage) of 0.95% of C, 0.15% of Si, 0.95% of Mn, 0.03% of P, 0.25% of S, and the balance of Fe and inevitable impurities. The wire rod is rolled into corresponding specification by a high-speed wire rod rolling mill and then is spun and coiled. The specific control parameters of the production process are as follows: the temperature of the preheating section of the billet is 750 ℃, the temperature of the heating I section is 1000 ℃, the temperature of the heating II section is 1200 ℃, the temperature of the soaking section is 1200 ℃, the temperature deviation of the head and the tail of the billet is less than or equal to 20 ℃, the total furnace residence time is controlled to be 3 hours, and the residual oxygen proportion (volume fraction) of the atmosphere of the heating furnace is controlled to be 1.0 percent. Taking the steel plate out of the heating furnace for high-pressure water descaling, starting the high-pressure water spraying for 0.5s in a delayed manner, wherein the descaling water pressure is 22 MPa; the initial rolling temperature is 1150 ℃, the inlet temperature of a finishing mill group is 1050 ℃, the temperature of the finishing mill group is 1000 ℃ and the spinning temperature is 830 ℃; stelmor air-cooled line parameters roller table speed are shown in the following table:
1, 2, 3, 21 and 22 of the heat preservation cover are opened, and the opening condition of the fan is shown in the following table:
1#
2#
3#
4#～22#
fan on condition
40％
25％
15％
Closing device
。
Comparative example 1
A rolling method of a high carbon free-cutting steel wire rod, the method comprising:
a high-carbon sulfur-series free-cutting steel casting blank with the section size of 150mm multiplied by 150mm is adopted to produce a wire rod with the specification of phi 9mm, and the wire rod comprises the chemical components (in mass percentage) of C1.10%, Si 0.50%, Mn 0.50%, P0.03%, S0.14%, Pb 0.35%, and the balance of Fe and inevitable impurities. The specific control parameters of the production process are as follows: the temperature of the preheating section of the steel billet is 700 ℃, the temperature of the heating I section is 900 ℃, the temperature of the heating II section is 1100 ℃, the temperature of the soaking section is 1100 ℃, the temperature deviation of the head and the tail of the steel billet is less than or equal to 20 ℃, the total furnace staying time is controlled to be 3 hours, and the residual oxygen proportion (volume fraction) of the atmosphere of the heating furnace is controlled to be 2.0 percent. Taking the mixture out of the heating furnace for high-pressure water descaling, wherein the descaling water pressure is 18 MPa; according to a conventional control method (low-temperature rolling and rapid cooling after rolling) for the net-shaped carbide of the high-carbon steel wire, the initial rolling temperature is set to 950 ℃, the inlet temperature of a finishing mill group is 850 ℃, the temperature of the finishing mill group is 800 ℃ and the spinning temperature is 780 ℃; stelmor air-cooled line parameters roller table speed are shown in the following table:
the heat preservation cover is closed completely, and the fan is closed completely.
Comparative example 2
A rolling method of a high carbon free-cutting steel wire rod, the method comprising:
a high-carbon lead-series free-cutting steel casting blank with the section size of 150mm multiplied by 150mm is adopted to produce a wire rod with the specification of phi 9mm, and the wire rod comprises the chemical components (in mass percentage) of C1.10%, Si 0.50%, Mn 0.50%, P0.03%, S0.14%, Pb 0.35%, and the balance of Fe and inevitable impurities. The wire rod is rolled into corresponding specification by a high-speed wire rod rolling mill and then is spun and coiled. The specific control parameters of the production process are as follows: the temperature of the preheating section of the billet is 750 ℃, the temperature of the heating I section is 950 ℃, the temperature of the heating II section is 1175 ℃, the temperature of the soaking section is 1150 ℃, the temperature deviation of the head and the tail of the billet is less than or equal to 20 ℃, the total furnace residence time is controlled to be 2.5 hours, and the residual oxygen proportion (volume fraction) of the atmosphere of the heating furnace is controlled to be 2.5 percent. Taking the mixture out of the heating furnace for high-pressure water descaling, wherein the descaling water pressure is 18 MPa; the rolling process is carried out according to a conventional free-cutting steel wire rolling method, wherein the initial rolling temperature is 1100 ℃, the inlet temperature of a finishing mill group is 1030 ℃, and the spinning temperature is 880 ℃; stelmor air-cooled line parameters roller table speed are shown in the following table:
the heat preservation cover is closed completely, and the fan is closed completely.
Examples of the experiments
The products obtained in examples 1 to 5 and comparative examples 1 to 2 were subjected to a net carbide rating, and the results are shown in the following table.
From the above table, the grade of the net-shaped carbide of the high-carbon free-cutting steel wire rod produced by the control method is less than or equal to 1.0 grade, and the net-shaped carbide is well controlled.
Detailed description of the drawings 2-6:
as shown in FIGS. 2 to 6, which are the optical metallographic structure diagrams of the cores of the high-carbon free-cutting steel wires obtained in examples 1 to 5, respectively, the grades of the network carbides of the high-carbon free-cutting steel wires produced by the control method of the present invention are all less than or equal to 1.0 grade, and the sorbite ratio is more than 80%.
As shown in FIG. 7, the core optical metallographic structure of the high carbon free-cutting steel wire obtained in comparative example 2 shows that the grade of the network carbide of the high carbon free-cutting steel wire produced by the conventional control method is not less than 1.5.
One or more technical solutions in the embodiments of the present invention at least have the following technical effects or advantages:
(1) the method provided by the embodiment of the invention can effectively control the net carbide grade of the high-carbon free-cutting steel wire rod to be below 1.0 grade, the sorbite proportion can reach 80-95%, the rolling is smooth, the surface defect rate is within 1%, and the spheroidizing annealing times of a downstream user are correspondingly reduced by 1-2 times along with the reduction of the net grade of the carbide of the hot-rolled wire rod.
Finally, it should also be noted that the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.
While preferred embodiments of the present invention have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. Therefore, it is intended that the appended claims be interpreted as including preferred embodiments and all such alterations and modifications as fall within the scope of the invention.
It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.
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