CN110904319B - Manufacturing process of high-carbon tool steel SK85 cold-rolled wide steel strip - Google Patents
Manufacturing process of high-carbon tool steel SK85 cold-rolled wide steel strip Download PDFInfo
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- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
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- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
- C21D8/0226—Hot rolling
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- C—CHEMISTRY; METALLURGY
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- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
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- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
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- C21D8/0247—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment
- C21D8/0268—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment between cold rolling steps
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- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
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Abstract
The invention discloses a manufacturing process of a high-carbon tool steel SK85 cold-rolled wide steel strip, which comprises the steps of smelting the steel in a converter, refining in an LF furnace, continuously casting a plate blank to obtain a continuous casting plate blank with the thickness of 210-230 mm, heating, continuously rolling and cooling the continuous casting plate blank to a coiling temperature through laminar flow to obtain a hot-rolled wide steel strip with the thickness of 2.5-6.0 mm, warehousing and slowly cooling the coiled hot-rolled wide steel strip to room temperature to obtain a fine-flake pearlite metallographic structure; the total reduction of the first cold rolling after pickling the hot-rolled wide steel strip is controlled to be 20-50%, then spheroidizing annealing is carried out, the Vickers hardness HV5 is below 180, and the spheroidizing rate is more than 92%; after the first spheroidizing annealing, carrying out second cold rolling on the steel strip, wherein the total cold rolling reduction is controlled to be 30-85%, and obtaining a cold-rolled wide steel strip with the specification of 0.70-3.00 mm; further spheroidizing annealing the steel strip subjected to the second cold rolling, wherein the Vickers hardness HV5 is below 175, and the spheroidizing rate is more than 94%; and then carrying out third cold rolling, wherein the total cold rolling reduction is controlled to be 50-85%, and the cold-rolled wide steel strip with the specification of 0.10-0.70 mm in thickness is obtained.
Description
Technical Field
The invention relates to the technical field of metal material forming, in particular to a manufacturing process of a high-carbon tool steel SK85 cold-rolled wide steel strip.
Background
The SK85 steel is a grade set by japanese standard JISG4401, and the chemical composition (mass percentage) of the steel: c: 0.80-0.90%, Si: 0.10 to 0.35%, Mn: 0.10-0.50%, P is less than or equal to 0.030%, S is less than or equal to 0.030%, Cr is less than or equal to 0.30%, Ni is less than or equal to 0.25%, and Cu is less than or equal to 0.25%. The product forms comprise hot rolled round steel, hot rolled steel plates and steel strips.
The high-carbon tool steel SK85 belongs to hypereutectoid steel, has a carbon content of 0.80% -0.90%, and has good strength, hardness and toughness, excellent wear resistance, excellent comprehensive performance and long service life after heat treatment. The method is mainly used for manufacturing cutters, measuring tools, saw blades, precise hardware tools, pen points, needles and the like, and is widely applied to the fields of engineering machinery, textile industry, electronics, automobiles and the like.
The thinner the thickness specification of the high-carbon tool steel SK85 cold-rolled steel strip is, the wider the plate surface is, the better the market favor is, but the production difficulty is high. Particularly, the market demand of large-width boards with the thickness of less than 0.70mm and the width of more than 1000mm is large, the additional value is high, and the economic benefit is remarkable. Since SK85 has high carbon content, large brittleness and obvious cold rolling work hardening, work hardening is generated in cold rolling, so that the deformation resistance is increased, and the continuous cold rolling is difficult. In order to ensure smooth cold rolling and rolling, spheroidizing annealing is required to eliminate work hardening. The thinner the thickness of the cold rolled product is, the more the number of cold rolling times is, and the more the number of spheroidizing annealing times is. The corresponding acceptance criteria for cold-rolled steel strip products are JISG 4802.
Through market research, the production mode of the high-carbon tool steel SK85 cold-rolled steel strip at present adopts the traditional cold-rolled narrow strip (the width is less than 600mm) process. The process flow mainly comprises two types: one is hot rolling narrow steel strip (width less than 600mm) → pickling → first spheroidizing annealing → first cold rolling → second spheroidizing annealing → Nth spheroidizing annealing, cold rolling. The other is hot-rolled wide steel strip (usually 1000mm to 1250mm in width) → slitting → pickling → first spheroidizing annealing → first cold rolling → second spheroidizing annealing → second cold rolling → Nth spheroidizing annealing, cold rolling. The two processes are to carry out spheroidizing annealing heat treatment on the hot-rolled coil for more than 10 hours before cold rolling so as to eliminate net-shaped or layered carbide and improve the cold rolling performance. And the first process flow also has the problems of large component fluctuation of the hot-rolled narrow steel strip, poor steel purity, poor dimensional precision, poor plate shape, poor quality stability, small coil weight, low production efficiency and the like, and the process flow tends to be eliminated. The technical problem of the second process flow is that the width of the surface of the hot-rolled wide steel strip cannot meet the width of the surface of the roller of the small single-stand cold rolling unit. The hot-rolled wide steel strip needs to be sheared, and the high-carbon tool steel SK85 has high carbon content, high brittleness, obvious shearing notch effect and high requirement on the longitudinal shearing quality of the edge of the steel strip. If the shearing quality of the edge of the steel strip is uneven, the technical problems of edge cracking, strip breakage and the like are easily caused in the subsequent cold rolling process. Similarly, because the high-carbon tool steel SK85 has high carbon content, obvious work hardening, large deformation resistance and difficult cold rolling processing, multiple cold rolling and spheroidizing annealing are required to be carried out repeatedly, the work hardening is eliminated, and the cold rolling and rolling performance is improved. Long production process, high production cost and low production efficiency.
By searching, the production process is set by a production method of the tool steel capable of being directly cold rolled (publication number: CN104745787A), the hot rolling heating temperature of a casting blank is controlled to be 1150-1250 ℃, the finish rolling temperature is controlled to be 800-900 ℃, the coiling temperature is Ms + 30-100 ℃, and the obtained structure is a martensite structure; and (3) tempering treatment is carried out after coiling, the tempering temperature is controlled to be 550-700 ℃, the tempering time is controlled to be 2-3 h, and the obtained tissue is a tempered sorbite. By adopting the process, the coiling temperature is too low, the martensite phase transformation occurs in the coiling process, the hot rolled steel strip has high tensile strength, poor elongation and high coiling difficulty, and the strip breakage production accident is easy to occur in the coiling process, so that the production risk is high.
According to the search, "a hypereutectoid tool steel and a method for producing the same" (publication No. CN108998730A), the coiling temperature is controlled to be 730 to 800 ℃. Coiling temperature is too high, and cooling rate is too slow, forms thick net carbide in the cooling process, and the pearlite structure is also bigger, and the plasticity is poor, rolls the easy broken strip, and the production risk is high.
Disclosure of Invention
Aiming at the technical problems of the existing production process, the invention provides the manufacturing process of the high-carbon tool steel SK85 cold-rolled wide steel strip, the hot-rolled raw materials do not need annealing and longitudinal shearing, and cold-rolled processing can be directly carried out to obtain the cold-rolled wide steel strip product, so that one-time annealing is reduced, the working procedure is shortened, and the production efficiency is improved.
The process flow adopted by the invention is as follows: converter smelting → LF furnace refining → slab continuous casting → heating → hot continuous rolling → laminar cooling → coiling → warehousing slow cooling → acid cleaning → first cold rolling → first spheroidizing annealing → second cold rolling (obtaining finished product with thickness of more than 0.70 mm) → second spheroidizing annealing → third cold rolling (obtaining finished product with thickness of 0.10-0.70 mm). A manufacturing process of a high-carbon tool steel SK85 cold-rolled wide steel strip comprises the following specific steps:
(1) smelting in a converter: conventionally smelting by adopting a top-bottom combined blown converter;
(2) refining in an LF furnace: smelting in a converter and then refining in an LF furnace to obtain chemical components in the SK85 brand range set by Japanese industrial standard JISG 4401;
(3) slab continuous casting: refining in an LF furnace, and then carrying out continuous casting, wherein the blank drawing speed is controlled to be 0.85-1.25 m/min, so that a continuous casting plate blank with the thickness of 210-230 mm and the width of 1000-1280 mm is obtained;
(4) heating: heating the continuous casting slab, and adopting a three-section heating mode, controlling the temperature of a preheating section to be 620-750 ℃, the temperature of a first heating section to be 1050-1150 ℃, the temperature of a second heating section to be 1150-1250 ℃, the temperature of a soaking section to be 1140-1240 ℃ and the in-furnace time to be 120-200 min;
(5) hot continuous rolling: carrying out hot continuous rolling on the heated continuous casting plate blank, and controlling the finish rolling temperature to be 840-890 ℃;
(6) laminar cooling: carrying out laminar cooling on the hot-rolled steel strip, controlling the cooling speed to be 26-60 ℃/s, and cooling to the coiling temperature;
(7) coiling: cooling the hot rolled steel strip, coiling, and controlling the coiling temperature to be 620-665 ℃ to obtain a hot rolled wide steel strip with the specification of 2.5-6.0 mm thickness and the width of 1000-1260 mm;
(8) and (4) warehousing and slow cooling: the coiled hot-rolled wide steel strip is put in a warehouse for slow cooling, the hot-rolled wide steel strip is hung into a pit type special slow cooling device for slow cooling treatment, and the steel strip is naturally cooled to room temperature, so that the obtained metallographic structure is fine lamellar pearlite;
(9) acid washing: slowly cooling to room temperature, and then pickling the hot-rolled wide steel strip, wherein the pickling speed is controlled to be 90-130 m/min, and the acid liquor temperature of an acid tank is 65-80 ℃;
(10) first cold rolling: after acid washing, cold rolling by adopting a single-frame reversible six-roller mill, wherein the total cold rolling reduction is controlled to be 0.50-1.5 mm, and the total cold rolling reduction is controlled to be 20-50%;
(11) first spheroidizing annealing: the steel strip after the first cold rolling is subjected to spheroidizing annealing by adopting a full-hydrogen strong-convection hood-type annealing furnace, a low-temperature and high-temperature alternative spheroidizing annealing process is adopted in a heat preservation section, after the heat preservation is finished, the steel strip is cooled to 500-600 ℃ along with the furnace, a cooling hood is replaced for air cooling, the steel strip is cooled to 280-340 ℃, water is sprayed and cooled to 80-100 ℃ for discharging, the Vickers hardness HV5 is below 180, and the spheroidizing rate is more than 92%;
(12) and (3) second cold rolling: after the first spheroidizing annealing, carrying out second cold rolling by adopting a single-frame reversible six-roller mill, wherein the total cold rolling reduction is controlled to be 0.70-1.70 mm, and the total cold rolling reduction is controlled to be 30-85%, so as to obtain a wide cold-rolled steel strip with the specification of 0.70-3.00 mm, the thickness of which is multiplied by 1000-1260 mm and the width of which is 0.70-3.00 mm;
(13) and (3) second spheroidizing annealing: the steel strip after the second cold rolling is spheroidized by adopting a full-hydrogen strong convection hood-type annealing furnace, a low-temperature and high-temperature alternative spheroidizing annealing process is adopted in a heat preservation section, after heat preservation is finished, the steel strip is cooled to 500-600 ℃ along with the furnace, a cooling hood is replaced for air cooling, the steel strip is cooled to 280-340 ℃, water is sprayed and cooled to 80-100 ℃ for discharging, the Vickers hardness HV5 is below 175, and the spheroidization rate is more than 94%;
(14) and (3) cold rolling for the third time: and after the second spheroidizing annealing, carrying out third cold rolling by adopting a single-frame reversible six-roller mill, wherein the total cold rolling reduction is controlled to be 0.40-1.00 mm, and the total cold rolling reduction is controlled to be 50-85%, so that the wide cold-rolled steel strip with the specification of 0.10-0.70 mm, the thickness and the width of 1000-1260 mm is obtained.
Further, the chemical components (mass percent) of the steel in the step (2) are as follows: c: 0.82 to 0.88%, Si: 0.12 to 0.28%, Mn: 0.25-0.45%, P is less than or equal to 0.025%, S is less than or equal to 0.010%, Cr is less than or equal to 0.05%, Ni is less than or equal to 0.05%, Cu is less than or equal to 0.05%, and the balance of Fe and inevitable impurity elements.
Further, a manufacturing process of the high-carbon tool steel SK85 cold-rolled wide steel strip comprises the following specific steps:
(1) smelting in a converter: conventionally smelting by adopting a top-bottom combined blown converter;
(2) refining in an LF furnace: smelting in a converter and then refining in an LF furnace to obtain chemical components in the SK85 brand range set by Japanese industrial standard JISG 4401;
(3) slab continuous casting: refining in an LF furnace, and then carrying out continuous casting, wherein the blank drawing speed is controlled to be 1.0-1.15 m/min, so that a continuous casting plate blank with the thickness of 210-230 mm and the width of 1000-1280 mm is obtained;
(4) heating: heating the continuous casting slab, and adopting a three-section type heating mode, wherein the temperature of a preheating section is controlled to be 630-730 ℃, the temperature of a first heating section is controlled to be 1080-1130 ℃, the temperature of a second heating section is controlled to be 1180-1230 ℃, the temperature of a soaking section is controlled to be 1170-1230 ℃, and the furnace time is controlled to be 150-180 min;
(5) hot continuous rolling: carrying out hot continuous rolling on the heated continuous casting plate blank, and controlling the finish rolling temperature to be 840-870 ℃;
(6) laminar cooling: carrying out laminar cooling on the hot-rolled steel strip, controlling the cooling speed to be 30-55 ℃/s, and cooling to the coiling temperature;
(7) coiling: cooling the hot rolled steel strip, coiling, and controlling the coiling temperature to be 630-660 ℃ to obtain a hot rolled wide steel strip with the specification of 2.5-6.0 mm thickness and the width of 1000-1260 mm;
(8) and (4) warehousing and slow cooling: the coiled hot-rolled wide steel strip is put in a warehouse for slow cooling, the hot-rolled wide steel strip is hung into a pit type special slow cooling device for slow cooling treatment, and the steel strip is naturally cooled to room temperature, so that the obtained metallographic structure is fine lamellar pearlite;
(9) acid washing: slowly cooling to room temperature, and then pickling the hot-rolled wide steel strip, wherein the pickling speed is controlled to be 96-126 m/min, and the acid liquor temperature of an acid tank is controlled to be 68-78 ℃;
(10) first cold rolling: after acid washing, cold rolling is carried out by adopting a single-frame reversible six-roller mill, the total cold rolling reduction is controlled to be 0.56-1.45 mm, and the total cold rolling reduction is controlled to be 24-48%;
(11) first spheroidizing annealing: the steel strip after the first cold rolling is spheroidized by adopting a full-hydrogen strong convection hood-type annealing furnace, and the heat preservation section adopts a low-temperature and high-temperature alternative spheroidizing annealing process; after heat preservation is finished, cooling to 535-585 ℃ along with the furnace, changing a cooling cover for air cooling, cooling to 300-325 ℃, spraying water, cooling to 83-97 ℃, discharging, wherein the Vickers hardness HV5 is below 175, and the nodularity is more than 93%;
(12) and (3) second cold rolling: after the first spheroidizing annealing, carrying out second cold rolling by adopting a single-frame reversible six-roller mill, wherein the total cold rolling reduction is controlled to be 0.75-1.65 mm, and the total cold rolling reduction is controlled to be 35-80%, so as to obtain a wide cold-rolled steel strip with the specification of 0.70-3.00 mm, the thickness of which is multiplied by 1000-1260 mm;
(13) and (3) second spheroidizing annealing: the steel strip after the second cold rolling is spheroidized by adopting a full-hydrogen strong convection hood-type annealing furnace, and the heat preservation section adopts a low-temperature and high-temperature alternative spheroidizing annealing process; after the heat preservation is finished, cooling to 515-590 ℃ along with the furnace, changing a cooling cover for air cooling, cooling to 297-317 ℃, spraying water and cooling to 82-94 ℃ to discharge, wherein the Vickers hardness HV5 is below 170, and the nodularity is above 95%;
(14) and (3) cold rolling for the third time: and after the second spheroidizing annealing, carrying out third cold rolling by adopting a single-frame reversible six-roller mill, wherein the total cold rolling reduction is controlled to be 0.45-1.00 mm, and the total cold rolling reduction is controlled to be 53-85%, so that the wide cold-rolled steel strip with the specification of 0.10-0.70 mm, the thickness and the width of 1000-1260 mm is obtained.
Further, the chemical components (mass percent) of the steel in the step (2) are as follows: c: 0.83 to 0.86%, Si: 0.15 to 0.25%, Mn: 0.30-0.40 percent of P, less than or equal to 0.020 percent of S, less than or equal to 0.006 percent of S, less than or equal to 0.03 percent of Cr, less than or equal to 0.03 percent of Ni, less than or equal to 0.04 percent of Cu, and the balance of Fe and inevitable impurity elements.
Further, the heat preservation section 'low-temperature and high-temperature alternative' spheroidizing annealing process comprises the following steps: heating the cold-rolled steel strip → heating up to 640-680 ℃ for 3-4 hours → heating up to 700-730 ℃ for 4-6 hours → cooling down to 640-680 ℃ for 3-4 hours.
Compared with the prior art, the invention has the following advantages:
1. the SK85 hot rolling wide steel strip adopts the technology of 'controlled rolling and controlled cooling and heat preservation slow cooling destressing', obtains fine lamellar pearlite structure with good performance, can be directly cold rolled without spheroidizing annealing and shearing and splitting, directly rolls wide plate surface with the thickness of more than 1000mm, reduces working procedures, saves energy, reduces cost and improves efficiency.
2. The steel strip subjected to cold rolling and calendering generates plastic deformation, the crystal lattice distortion energy is increased, the dislocation density is increased, and the steel strip has larger deformation energy; the original crystal grains are fine, the area of a crystal boundary in unit volume is increased, the spherical nucleation points are increased, and the spheroidizing annealing is easy. The heat preservation section adopts a low-temperature and high-temperature alternative spheroidizing annealing process, the diffusion of C atoms is intensified, the nucleation amount of carbides is increased, uniformly distributed granular pearlite structures can be effectively obtained, the Vickers hardness HV5 is below 180, and the spheroidization rate is more than 92%. The steel strip can obtain the optimal spheroidization structure and performance, can be subjected to cold rolling processing by adopting the high reduction rate of 50-85%, reduces rolling passes, reduces the cost, obviously improves the production efficiency, and ensures the product quality.
Drawings
FIG. 1 shows a fine lamellar pearlite structure obtained after slow cooling of a hot-rolled wide steel strip according to the present invention.
FIG. 2 is a graph of the spheroidizing annealing process of the present invention using "low temperature and high temperature alternation".
Fig. 3 is a granular pearlite structure obtained after the first spheroidizing annealing of the present invention.
FIG. 4 is a granular pearlite structure obtained after the second spheroidizing annealing according to the present invention.
Detailed Description
The invention is further illustrated with reference to the following figures and examples. Referring to fig. 1 to 4, a manufacturing process of a high-carbon tool steel SK85 cold-rolled wide steel strip includes the following specific steps:
(1) smelting in a converter: conventionally smelting by adopting a top-bottom combined blown converter;
(2) refining in an LF furnace: the steel is refined in an LF furnace after being smelted in a converter, and the steel obtains the chemical components in the SK85 brand range set by Japanese industrial standard JISG4401, and the specific chemical components (mass percent) are as follows: c: 0.82 to 0.88%, Si: 0.12 to 0.28%, Mn: 0.25-0.45%, P is less than or equal to 0.025%, S is less than or equal to 0.010%, Cr is less than or equal to 0.05%, Ni is less than or equal to 0.05%, Cu is less than or equal to 0.05%, and the balance of Fe and inevitable impurity elements;
(3) slab continuous casting: refining in an LF furnace, and then carrying out continuous casting, wherein the blank drawing speed is controlled to be 0.85-1.25 m/min, so that a continuous casting plate blank with the thickness of 210-230 mm and the width of 1000-1280 mm is obtained;
(4) heating: heating the continuous casting slab, and adopting a three-section heating mode, controlling the temperature of a preheating section to be 620-750 ℃, the temperature of a first heating section to be 1050-1150 ℃, the temperature of a second heating section to be 1150-1250 ℃, the temperature of a soaking section to be 1140-1240 ℃ and the in-furnace time to be 120-200 min;
(5) hot continuous rolling: carrying out hot continuous rolling on the heated continuous casting plate blank, and controlling the finish rolling temperature to be 840-890 ℃;
(6) laminar cooling: carrying out laminar cooling on the hot-rolled steel strip, controlling the cooling speed to be 26-60 ℃/s, and cooling to the coiling temperature;
(7) coiling: cooling the hot rolled steel strip, coiling, and controlling the coiling temperature to be 620-665 ℃ to obtain a hot rolled wide steel strip with the specification of 2.5-6.0 mm thickness and the width of 1000-1260 mm;
(8) and (4) warehousing and slow cooling: the coiled hot-rolled wide steel strip is put in a warehouse for slow cooling, the hot-rolled wide steel strip is hung into a pit type special slow cooling device for slow cooling treatment, and the hot-rolled wide steel strip is naturally cooled to room temperature, so that the obtained metallographic structure is fine lamellar pearlite (detailed shown in figure 1);
(9) acid washing: slowly cooling to room temperature, and then pickling the hot-rolled wide steel strip, wherein the pickling speed is controlled to be 90-130 m/min, and the acid liquor temperature of an acid tank is 65-80 ℃;
(10) first cold rolling: after acid washing, cold rolling by adopting a single-frame reversible six-roller mill, wherein the total cold rolling reduction is controlled to be 0.50-1.5 mm, and the total cold rolling reduction is controlled to be 20-50%;
(11) first spheroidizing annealing: the steel strip after the first cold rolling is subjected to spheroidizing annealing by adopting a full-hydrogen strong convection hood-type annealing furnace, a heat preservation section adopts a low-temperature and high-temperature alternative spheroidizing annealing process, the spheroidizing annealing process is detailed in figure 2, after the heat preservation is finished, the steel strip is cooled to 500-600 ℃ along with the furnace, a cooling hood is replaced for air cooling, the steel strip is cooled to 280-340 ℃, water is sprayed and cooled to 80-100 ℃ for discharging, the Vickers hardness HV5 is below 180, and the spheroidization rate is more than 92%, so that a granular pearlite structure is obtained (detailed in figure 3;
(12) and (3) second cold rolling: after the first spheroidizing annealing, carrying out second cold rolling by adopting a single-frame reversible six-roller mill, wherein the total cold rolling reduction is controlled to be 0.70-1.70 mm, and the total cold rolling reduction is controlled to be 30-85%, so as to obtain a wide cold-rolled steel strip with the specification of 0.70-3.00 mm, the thickness of which is multiplied by 1000-1260 mm and the width of which is 0.70-3.00 mm;
(13) and (3) second spheroidizing annealing: the steel strip after the second cold rolling is subjected to spheroidizing annealing by adopting a full-hydrogen strong convection hood-type annealing furnace, a heat preservation section adopts a low-temperature and high-temperature alternative spheroidizing annealing process, the spheroidizing annealing process is detailed in figure 2, after heat preservation is finished, the steel strip is cooled to 500-600 ℃ along with the furnace, a cooling hood is replaced for air cooling, the steel strip is cooled to 280-340 ℃, water is sprayed and cooled to 80-100 ℃ for discharging, the Vickers hardness HV5 is below 175, and the spheroidization rate is more than 94%, so that a granular pearlite structure (detailed in figure 4) is obtained;
(14) and (3) cold rolling for the third time: and after the second spheroidizing annealing, carrying out third cold rolling by adopting a single-frame reversible six-roller mill, wherein the total cold rolling reduction is controlled to be 0.40-1.00 mm, and the total cold rolling reduction is controlled to be 50-85%, so that the wide cold-rolled steel strip with the specification of 0.10-0.70 mm, the thickness and the width of 1000-1260 mm is obtained.
Further, a manufacturing process of the high-carbon tool steel SK85 cold-rolled wide steel strip comprises the following specific steps:
(1) smelting in a converter: conventionally smelting by adopting a top-bottom combined blown converter;
(2) refining in an LF furnace: smelting in a converter and then refining in an LF furnace to obtain the chemical components in the SK85 brand range set by Japanese industrial standard JISG4401, wherein the specific chemical components (mass percent) are as follows: c: 0.83 to 0.86%, Si: 0.15 to 0.25%, Mn: 0.30-0.40 percent of Fe, less than or equal to 0.020 percent of P, less than or equal to 0.006 percent of S, less than or equal to 0.03 percent of Cr, less than or equal to 0.03 percent of Ni, less than or equal to 0.04 percent of Cu, and the balance of Fe and inevitable impurity elements;
(3) slab continuous casting: refining in an LF furnace, and then carrying out continuous casting, wherein the blank drawing speed is controlled to be 1.0-1.15 m/min, so that a continuous casting plate blank with the thickness of 210-230 mm and the width of 1000-1280 mm is obtained;
(4) heating: heating the continuous casting slab, and adopting a three-section type heating mode, wherein the temperature of a preheating section is controlled to be 630-730 ℃, the temperature of a first heating section is controlled to be 1080-1130 ℃, the temperature of a second heating section is controlled to be 1180-1230 ℃, the temperature of a soaking section is controlled to be 1170-1230 ℃, and the furnace time is controlled to be 150-180 min;
(5) hot continuous rolling: carrying out hot continuous rolling on the heated continuous casting plate blank, and controlling the finish rolling temperature to be 840-870 ℃;
(6) laminar cooling: carrying out laminar cooling on the hot-rolled steel strip, controlling the cooling speed to be 30-55 ℃/s, and cooling to the coiling temperature;
(7) coiling: cooling the hot rolled steel strip, coiling, and controlling the coiling temperature to be 630-660 ℃ to obtain a hot rolled wide steel strip with the specification of 2.5-6.0 mm thickness and the width of 1000-1260 mm;
(8) and (4) warehousing and slow cooling: the coiled hot-rolled wide steel strip is put in a warehouse for slow cooling, the hot-rolled wide steel strip is hung into a pit type special slow cooling device for slow cooling treatment, and the steel strip is naturally cooled to room temperature, so that the obtained metallographic structure is fine lamellar pearlite (shown in figure 1);
(9) acid washing: slowly cooling to room temperature, and then pickling the hot-rolled wide steel strip, wherein the pickling speed is controlled to be 96-126 m/min, and the acid liquor temperature of an acid tank is controlled to be 68-78 ℃;
(10) first cold rolling: after acid washing, cold rolling is carried out by adopting a single-frame reversible six-roller mill, the total cold rolling reduction is controlled to be 0.56-1.45 mm, and the total cold rolling reduction is controlled to be 24-48%;
(11) first spheroidizing annealing: the steel strip after the first cold rolling is subjected to spheroidizing annealing by adopting a full-hydrogen strong convection hood-type annealing furnace, a heat preservation section adopts a low-temperature and high-temperature alternative spheroidizing annealing process, the spheroidizing annealing process is detailed in figure 2, after the heat preservation is finished, the steel strip is cooled to 535-585 ℃ along with the furnace, the cooling hood is replaced for air cooling, the steel strip is cooled to 300-325 ℃, water is sprayed and cooled to 83-97 ℃ for discharging, the Vickers hardness HV5 is below 175, and the spheroidization rate is more than 93%, so that a granular pearlite structure is obtained (shown in figure;
(12) and (3) second cold rolling: after the first spheroidizing annealing, carrying out second cold rolling by adopting a single-frame reversible six-roller mill, wherein the total cold rolling reduction is controlled to be 0.75-1.65 mm, and the total cold rolling reduction is controlled to be 35-80%, so as to obtain a wide cold-rolled steel strip with the specification of 0.70-3.00 mm, the thickness of which is multiplied by 1000-1260 mm;
(13) and (3) second spheroidizing annealing: the steel strip after the second cold rolling is subjected to spheroidizing annealing by adopting a full-hydrogen strong convection hood-type annealing furnace, a heat preservation section adopts a low-temperature and high-temperature alternative spheroidizing annealing process, the spheroidizing annealing process is detailed in figure 2, after the heat preservation is finished, the steel strip is cooled to 515-590 ℃ along with the furnace, a cooling hood is replaced for air cooling, the steel strip is cooled to 297-317 ℃, water is sprayed and cooled to 82-94 ℃, the steel strip is discharged from the furnace, the Vickers hardness HV5 is below 170, and the spheroidization rate is more than 95%, so that a granular pearlite structure (;
(14) and (3) cold rolling for the third time: and after the second spheroidizing annealing, carrying out third cold rolling by adopting a single-frame reversible six-roller mill, wherein the total cold rolling reduction is controlled to be 0.45-1.00 mm, and the total cold rolling reduction is controlled to be 53-85%, so that the wide cold-rolled steel strip with the specification of 0.10-0.70 mm, the thickness and the width of 1000-1260 mm is obtained.
As shown in fig. 2, the "low-temperature and high-temperature alternating" spheroidizing annealing process of the heat preservation section is as follows: heating the cold-rolled steel strip → heating up to 640-680 ℃ for 3-4 hours → heating up to 700-730 ℃ for 4-6 hours → cooling down to 640-680 ℃ for 3-4 hours.
Example 1: the example produces the high carbon tool steel SK85 cold rolled wide steel strip with the specification of 0.70mm thickness multiplied by 1250mm width, and the production steps are as follows:
(1) smelting in a converter: smelting by adopting a 210t converter;
(2) LF refining: smelting in a converter, and then performing LF refining, wherein the main chemical components of the molten steel measured after refining are C in percentage by mass: 0.85%, Si: 0.18%, Mn: 0.33%, P: 0.0: 18%, S: 0.005%, Cr: 0.01%, Ni: 0.01%, Cu: 0.02% and the balance of Fe and inevitable impurity elements;
(3) continuous casting: continuous casting is carried out after LF refining, the superheat degree of molten steel is 16 ℃, and the blank drawing speed is 1.08m/min, so that a continuous casting plate blank with the thickness of 230mm and the width of 1260mm is obtained;
(4) heating: heating the continuous casting plate blank by adopting a three-section heating mode, wherein the temperature of a preheating section is 675 ℃, the temperature of a first heating section is 1098 ℃, the temperature of a second heating section is 1224 ℃, the temperature of a soaking section is 1217 ℃, and the in-furnace time is 167 min;
(5) hot continuous rolling: carrying out hot continuous rolling on the heated continuous casting plate blank, wherein the finish rolling temperature is 858 ℃;
(6) laminar cooling: carrying out laminar cooling on the hot-rolled steel strip, controlling the cooling speed to be 38 ℃/s, and cooling to the coiling temperature;
(7) coiling: cooling the hot rolled steel strip, coiling, controlling the coiling temperature to be 648 ℃ to obtain a hot rolled wide steel strip with the specification of 3.0mm thickness and 1250mm width;
(8) and (4) warehousing and slow cooling: the coiled hot-rolled wide steel strip is put in a warehouse for slow cooling, the hot-rolled wide steel strip is hung into a pit type special slow cooling device for slow cooling treatment, the temperature is reduced to room temperature after natural slow cooling for 58 hours, and the obtained metallographic structure is fine lamellar pearlite (detailed shown in figure 1);
(9) acid washing: slowly cooling to room temperature, and then pickling the hot-rolled wide steel strip, wherein the pickling speed is controlled to be 107m/min, and the acid bath temperature of an acid bath is 73 ℃;
(10) first cold rolling: after acid washing, cold rolling is carried out by adopting a 1450mm single-stand reversible six-roller mill, the total rolling reduction of the cold rolling is 1.23mm, and the total rolling reduction of the cold rolling is 41 percent; rolling in four passes, and sequentially deforming the size: 3.0mm → 2.57mm → 2.16mm → 1.89mm → 1.77 mm;
(11) first spheroidizing annealing: the steel strip after the first cold rolling is subjected to spheroidizing annealing by adopting a full-hydrogen strong convection hood-type annealing furnace, a heat preservation section adopts a low-temperature and high-temperature alternative spheroidizing annealing process, the spheroidizing annealing process is detailed in figure 2, after the heat preservation is finished, the steel strip is cooled to 564 ℃ along with the furnace, a cooling hood is replaced for air cooling, the steel strip is cooled to 316 ℃, water is sprayed and cooled to 88 ℃, and the steel strip is discharged from the furnace to obtain a granular pearlite structure (detailed in figure 3);
(12) and (3) second cold rolling: after the first spheroidizing annealing, the steel strip is subjected to second cold rolling by adopting a 1450mm single-rack reversible six-roller mill, the total rolling reduction of the cold rolling is 1.07mm, the total rolling reduction of the cold rolling is 60.5 percent, the steel strip is rolled in four passes, and the steel strip is sequentially deformed: 1.77mm → 1.45mm → 1.12mm → 0.87mm → 0.70mm, and the finished product specification of the cold-rolled wide steel strip with the thickness of 0.70mm and the width of 1250mm is obtained, and the product quality meets the JIS G4802 acceptance standard.
Example 2 this example produced a high carbon tool steel SK85 cold rolled wide strip with gauge 0.15mm thick x 1100mm wide produced by the following steps:
(1) smelting in a converter: smelting by adopting a 210t converter;
(2) LF refining: smelting in a converter, and then performing LF refining, wherein the main chemical components of the molten steel measured after refining are C in percentage by mass: 0.86%, Si: 0.19%, Mn: 0.36%, P: 0.0: 17%, S: 0.004%, Cr: 0.01%, Ni: 0.01%, Cu: 0.02% and the balance of Fe and inevitable impurity elements;
(3) continuous casting: continuous casting is carried out after LF refining, the superheat degree of molten steel is 18 ℃, the drawing speed is 1.04m/min, and a continuous casting plate blank with the thickness of 230mm and the width of 1120mm is obtained;
(4) heating: heating the continuous casting plate blank by adopting a three-section type heating mode, controlling the temperature of a preheating section to be 656 ℃, the temperature of a first heating section to be 1114 ℃, the temperature of a second heating section to be 1220 ℃, the temperature of a soaking section to be 1194 ℃ and the in-furnace time to be 171 min;
(5) hot continuous rolling: carrying out hot continuous rolling on the heated continuous casting plate blank, wherein the finish rolling temperature is 863 ℃;
(6) laminar cooling: carrying out laminar cooling on the hot-rolled steel strip, controlling the cooling speed to be 42 ℃/s, and cooling to the coiling temperature;
(7) coiling: cooling the hot rolled steel strip, and then coiling, wherein the coiling temperature is controlled to be 647 ℃; a hot-rolled wide steel strip having a gauge of 2.5mm in thickness and 1100mm in width was obtained.
(8) And (4) warehousing and slow cooling: the coiled hot-rolled wide steel strip is put in a warehouse for slow cooling, the hot-rolled wide steel strip is hung into a pit type special slow cooling device for slow cooling treatment, and after the hot-rolled wide steel strip is naturally and slowly cooled for 68 hours to the room temperature, the obtained metallographic structure is fine lamellar pearlite (detailed shown in figure 1);
(9) acid washing: slowly cooling to room temperature, and then carrying out acid pickling on the hot-rolled wide steel strip, wherein the acid pickling speed is 104m/min, and the acid bath acid liquor temperature is 69 ℃;
(10) first cold rolling: after acid washing, cold rolling is carried out by adopting a 1450mm single-stand reversible six-roller mill, the total rolling reduction of the cold rolling is 0.99mm, the total rolling reduction of the cold rolling is 39.6%, the cold rolling is carried out by three passes until the cold rolling is 1.51mm, and the cold rolling is sequentially deformed: 2.5mm → 2.13mm → 1.78mm → 1.51 mm;
(11) first spheroidizing annealing: the steel strip after the first cold rolling is subjected to spheroidizing annealing by adopting a full-hydrogen strong convection hood-type annealing furnace, a heat preservation section adopts a low-temperature and high-temperature alternative spheroidizing annealing process, the spheroidizing annealing process is shown in figure 2, after the heat preservation is finished, the steel strip is cooled to 566 ℃ along with the furnace, a cooling hood is replaced for air cooling, the steel strip is cooled to 308 ℃, water is sprayed and cooled to 87 ℃, and the steel strip is discharged from the furnace to obtain a granular pearlite structure (detailed figure 3);
(12) and (3) second cold rolling: after the first spheroidizing annealing, the steel strip is subjected to second cold rolling by adopting a 1450mm single-rack reversible six-roller mill, the total rolling reduction of the cold rolling is 0.86mm, the total rolling reduction of the cold rolling is controlled to be 57 percent, and the steel strip is subjected to three-pass rolling and sequentially deforms to the size: 1.51mm → 1.18mm → 0.88mm → 0.65 mm;
(13) and (3) second spheroidizing annealing: the steel strip after the second cold rolling is subjected to spheroidizing annealing by adopting a full-hydrogen strong convection hood-type annealing furnace, a heat preservation section adopts a low-temperature and high-temperature alternative spheroidizing annealing process, as shown in figure 2, after heat preservation is finished, the steel strip is cooled to 536 ℃ along with the furnace, a cooling hood is replaced for air cooling, the steel strip is cooled to 304 ℃, water is sprayed and cooled to 84 ℃, and the steel strip is discharged from the furnace to obtain a granular pearlite structure (as shown in figure 4 in detail);
(14) and (3) cold rolling for the third time: after the second spheroidizing annealing, the steel strip is subjected to third cold rolling by adopting a 1450mm single-rack reversible six-roller mill, the total cold rolling reduction is controlled to be 0.50mm, the total cold rolling reduction is 77%, the steel strip is rolled in three passes, and the steel strip is sequentially deformed by the size: 0.65mm → 0.46mm → 0.29mm → 0.15 mm; the cold-rolled wide steel strip with the finished specification of 0.15mm thickness multiplied by 1100mm width is obtained, and the product quality meets the JIS G4802 acceptance standard.
The chemical components, process parameters and product performance of the representative finished products with various specifications are shown in the following table: table 1 shows the chemical composition of the steels of the examples of the present invention. Table 2 shows the manufacturing process parameters of the hot-rolled wide steel strip according to each example of the present invention, table 3 shows the manufacturing process of the cold-rolled wide steel strip according to each example of the present invention, and table 4 shows the properties and metallographic structure of the cold-rolled wide steel strip according to each example of the present invention.
TABLE 1 chemical composition (mass%) of steels according to examples of the present invention
| Case(s) | C | Mn | Si | S | P | Cr | Ni | Cu |
| Example 1 | 0.85 | 0.33 | 0.18 | 0.005 | 0.018 | 0.01 | 0.01 | 0.02 |
| Example 2 | 0.86 | 0.36 | 0.19 | 0.004 | 0.017 | 0.01 | 0.01 | 0.02 |
| Example 3 | 0.83 | 0.33 | 0.18 | 0.005 | 0.016 | 0.02 | 0.01 | 0.02 |
| Example 4 | 0.84 | 0.34 | 0.19 | 0.004 | 0.015 | 0.02 | 0.01 | 0.01 |
| Example 5 | 0.84 | 0.35 | 0.20 | 0.006 | 0.017 | 0.01 | 0.02 | 0.03 |
| Example 6 | 0.82 | 0.34 | 0.17 | 0.003 | 0.015 | 0.02 | 0.01 | 0.03 |
| Example 7 | 0.83 | 0.35 | 0.19 | 0.005 | 0.018 | 0.03 | 0.02 | 0.02 |
| Example 8 | 0.84 | 0.34 | 0.17 | 0.003 | 0.015 | 0.02 | 0.01 | 0.04 |
| Example 9 | 0.84 | 0.35 | 0.19 | 0.004 | 0.017 | 0.02 | 0.01 | 0.03 |
| Example 10 | 0.83 | 0.35 | 0.22 | 0.006 | 0.018 | 0.02 | 0.01 | 0.03 |
| Example 11 | 0.83 | 0.34 | 0.21 | 0.003 | 0.016 | 0.02 | 0.01 | 0.04 |
| Example 12 | 0.83 | 0.36 | 0.23 | 0.004 | 0.017 | 0.02 | 0.01 | 0.03 |
| Example 13 | 0.84 | 0.34 | 0.22 | 0.005 | 0.018 | 0.02 | 0.01 | 0.03 |
| Example 14 | 0.83 | 0.35 | 0.20 | 0.004 | 0.017 | 0.02 | 0.01 | 0.02 |
TABLE 2 Process parameters for the manufacture of hot-rolled wide steel strip according to the invention in the examples
Table 3 shows the manufacturing process parameters of the cold-rolled wide steel strip according to the examples of the invention
Table 4 shows the properties of the cold-rolled wide steel strips according to the examples of the invention
Claims (10)
1. A manufacturing process of a high-carbon tool steel SK85 cold-rolled wide steel strip comprises the following specific steps:
(1) smelting in a converter: conventionally smelting by adopting a top-bottom combined blown converter;
(2) refining in an LF furnace: smelting in a converter and then refining in an LF furnace to obtain chemical components in the SK85 brand range set by JIS G4401;
(3) slab continuous casting: refining in an LF furnace, and then carrying out continuous casting, wherein the blank drawing speed is controlled to be 0.85-1.25 m/min, so that a continuous casting plate blank with the thickness of 210-230 mm and the width of 1000-1280 mm is obtained;
(4) heating: heating the continuous casting slab, and adopting a three-section heating mode, controlling the temperature of a preheating section to be 620-750 ℃, the temperature of a first heating section to be 1050-1150 ℃, the temperature of a second heating section to be 1150-1250 ℃, the temperature of a soaking section to be 1140-1240 ℃ and the in-furnace time to be 120-200 min;
(5) hot continuous rolling: carrying out hot continuous rolling on the heated continuous casting plate blank, and controlling the finish rolling temperature to be 840-890 ℃;
(6) laminar cooling: carrying out laminar cooling on the hot-rolled steel strip, controlling the cooling speed to be 26-60 ℃/s, and cooling to the coiling temperature;
(7) coiling: cooling the hot rolled steel strip, coiling, and controlling the coiling temperature to be 620-665 ℃ to obtain a hot rolled wide steel strip with the specification of 2.5-6.0 mm thickness and the width of 1000-1260 mm;
(8) and (4) warehousing and slow cooling: the coiled hot-rolled wide steel strip is put in a warehouse for slow cooling, the hot-rolled wide steel strip is hung into a pit type special slow cooling device for slow cooling treatment, and the steel strip is naturally cooled to room temperature, so that the obtained metallographic structure is fine lamellar pearlite;
(9) acid washing: slowly cooling to room temperature, and then pickling the hot-rolled wide steel strip, wherein the pickling speed is controlled to be 90-130 m/min, and the acid liquor temperature of an acid tank is 65-80 ℃;
(10) first cold rolling: after acid washing, cold rolling by adopting a single-frame reversible six-roller mill, wherein the total cold rolling reduction is controlled to be 0.50-1.5 mm, and the total cold rolling reduction is controlled to be 20-50%;
(11) first spheroidizing annealing: the steel strip after the first cold rolling is subjected to spheroidizing annealing by adopting a full-hydrogen strong-convection hood-type annealing furnace, a low-temperature and high-temperature alternative spheroidizing annealing process is adopted in a heat preservation section, after the heat preservation is finished, the steel strip is cooled to 500-600 ℃ along with the furnace, a cooling hood is replaced for air cooling, the steel strip is cooled to 280-340 ℃, water is sprayed and cooled to 80-100 ℃ for discharging, the Vickers hardness HV5 is below 180, and the spheroidizing rate is more than 92%;
(12) and (3) second cold rolling: after the first spheroidizing annealing, the steel strip is subjected to second cold rolling by a single-frame reversible six-roller mill, the total cold rolling reduction is controlled to be 0.70-1.70 mm, and the total cold rolling reduction is controlled to be 30-85%, so that the wide cold-rolled steel strip with the specification of 0.70-3.00 mm, the thickness and the width of 1000-1260 mm is obtained.
2. The manufacturing process of the high-carbon tool steel SK85 cold-rolled wide steel strip as claimed in claim 1 is characterized by comprising the following steps:
(1) smelting in a converter: conventionally smelting by adopting a top-bottom combined blown converter;
(2) refining in an LF furnace: smelting in a converter and then refining in an LF furnace to obtain chemical components in the SK85 brand range set by JIS G4401;
(3) slab continuous casting: refining in an LF furnace, and then carrying out continuous casting, wherein the blank drawing speed is controlled to be 1.0-1.15 m/min, so that a continuous casting plate blank with the thickness of 210-230 mm and the width of 1000-1280 mm is obtained;
(4) heating: heating the continuous casting slab, and adopting a three-section type heating mode, wherein the temperature of a preheating section is controlled to be 630-730 ℃, the temperature of a first heating section is controlled to be 1080-1130 ℃, the temperature of a second heating section is controlled to be 1180-1230 ℃, the temperature of a soaking section is controlled to be 1170-1230 ℃, and the furnace time is controlled to be 150-180 min;
(5) hot continuous rolling: carrying out hot continuous rolling on the heated continuous casting plate blank, and controlling the finish rolling temperature to be 840-870 ℃;
(6) laminar cooling: carrying out laminar cooling on the hot-rolled steel strip, controlling the cooling speed to be 30-55 ℃/s, and cooling to the coiling temperature;
(7) coiling: cooling the hot rolled steel strip, coiling, and controlling the coiling temperature to be 630-660 ℃ to obtain a hot rolled wide steel strip with the specification of 2.5-6.0 mm thickness and the width of 1000-1260 mm;
(8) and (4) warehousing and slow cooling: the coiled hot-rolled wide steel strip is put in a warehouse for slow cooling, the hot-rolled wide steel strip is hung into a pit type special slow cooling device for slow cooling treatment, and the steel strip is naturally cooled to room temperature, so that the obtained metallographic structure is fine lamellar pearlite;
(9) acid washing: slowly cooling to room temperature, and then pickling the hot-rolled wide steel strip, wherein the pickling speed is controlled to be 96-126 m/min, and the acid liquor temperature of an acid tank is controlled to be 68-78 ℃;
(10) first cold rolling: after acid washing, cold rolling is carried out by adopting a single-frame reversible six-roller mill, the total cold rolling reduction is controlled to be 0.56-1.45 mm, and the total cold rolling reduction is controlled to be 24-48%;
(11) first spheroidizing annealing: the steel strip after the first cold rolling is spheroidized by adopting a full-hydrogen strong convection hood-type annealing furnace, and the heat preservation section adopts a low-temperature and high-temperature alternative spheroidizing annealing process; after heat preservation is finished, cooling to 535-585 ℃ along with the furnace, changing a cooling cover for air cooling, cooling to 300-325 ℃, spraying water, cooling to 83-97 ℃, discharging, wherein the Vickers hardness HV5 is below 175, and the nodularity is more than 93%;
(12) and (3) second cold rolling: after the first spheroidizing annealing, the steel strip is subjected to second cold rolling by a single-frame reversible six-roller mill, the total cold rolling reduction is controlled to be 0.75-1.65 mm, and the total cold rolling reduction is controlled to be 35-80%, so that the wide cold-rolled steel strip with the specification of 0.70-3.00 mm, the thickness and the width of 1000-1260 mm is obtained.
3. The manufacturing process of the high-carbon tool steel SK85 cold-rolled wide steel strip as claimed in claim 1, wherein the chemical composition of the steel of step (2) is as follows by mass percent: c: 0.82 to 0.88%, Si: 0.12 to 0.28%, Mn: 0.25-0.45%, P is less than or equal to 0.025%, S is less than or equal to 0.010%, Cr is less than or equal to 0.05%, Ni is less than or equal to 0.05%, Cu is less than or equal to 0.05%, and the balance of Fe and inevitable impurity elements.
4. The manufacturing process of the high-carbon tool steel SK85 cold-rolled wide steel strip as claimed in claim 2, wherein the chemical composition of the steel in the step (2) is as follows by mass percent: c: 0.83 to 0.86%, Si: 0.15 to 0.25%, Mn: 0.30-0.40 percent of P, less than or equal to 0.020 percent of S, less than or equal to 0.006 percent of S, less than or equal to 0.03 percent of Cr, less than or equal to 0.03 percent of Ni, less than or equal to 0.04 percent of Cu, and the balance of Fe and inevitable impurity elements.
5. The manufacturing process of the high-carbon tool steel SK85 cold-rolled wide steel strip as claimed in claim 1 or 2, wherein the heat-preservation section "low-temperature and high-temperature alternating" spheroidizing annealing process is as follows: heating the cold-rolled steel strip → heating up to 640-680 ℃ for 3-4 hours → heating up to 700-730 ℃ for 4-6 hours → cooling down to 640-680 ℃ for 3-4 hours.
6. A manufacturing process of a high-carbon tool steel SK85 cold-rolled wide steel strip comprises the following specific steps:
(1) smelting in a converter: conventionally smelting by adopting a top-bottom combined blown converter;
(2) refining in an LF furnace: smelting in a converter and then refining in an LF furnace to obtain chemical components in the SK85 brand range set by JIS G4401;
(3) slab continuous casting: refining in an LF furnace, and then carrying out continuous casting, wherein the blank drawing speed is controlled to be 0.85-1.25 m/min, so that a continuous casting plate blank with the thickness of 210-230 mm and the width of 1000-1280 mm is obtained;
(4) heating: heating the continuous casting slab, and adopting a three-section heating mode, controlling the temperature of a preheating section to be 620-750 ℃, the temperature of a first heating section to be 1050-1150 ℃, the temperature of a second heating section to be 1150-1250 ℃, the temperature of a soaking section to be 1140-1240 ℃ and the in-furnace time to be 120-200 min;
(5) hot continuous rolling: carrying out hot continuous rolling on the heated continuous casting plate blank, and controlling the finish rolling temperature to be 840-890 ℃;
(6) laminar cooling: carrying out laminar cooling on the hot-rolled steel strip, controlling the cooling speed to be 26-60 ℃/s, and cooling to the coiling temperature;
(7) coiling: cooling the hot rolled steel strip, coiling, and controlling the coiling temperature to be 620-665 ℃ to obtain a hot rolled wide steel strip with the specification of 2.5-6.0 mm thickness and the width of 1000-1260 mm;
(8) and (4) warehousing and slow cooling: the coiled hot-rolled wide steel strip is put in a warehouse for slow cooling, the hot-rolled wide steel strip is hung into a pit type special slow cooling device for slow cooling treatment, and the steel strip is naturally cooled to room temperature, so that the obtained metallographic structure is fine lamellar pearlite;
(9) acid washing: slowly cooling to room temperature, and then pickling the hot-rolled wide steel strip, wherein the pickling speed is controlled to be 90-130 m/min, and the acid liquor temperature of an acid tank is 65-80 ℃;
(10) first cold rolling: after acid washing, cold rolling by adopting a single-frame reversible six-roller mill, wherein the total cold rolling reduction is controlled to be 0.50-1.5 mm, and the total cold rolling reduction is controlled to be 20-50%;
(11) first spheroidizing annealing: the steel strip after the first cold rolling is subjected to spheroidizing annealing by adopting a full-hydrogen strong-convection hood-type annealing furnace, a low-temperature and high-temperature alternative spheroidizing annealing process is adopted in a heat preservation section, after the heat preservation is finished, the steel strip is cooled to 500-600 ℃ along with the furnace, a cooling hood is replaced for air cooling, the steel strip is cooled to 280-340 ℃, water is sprayed and cooled to 80-100 ℃ for discharging, the Vickers hardness HV5 is below 180, and the spheroidizing rate is more than 92%;
(12) and (3) second cold rolling: after the first spheroidizing annealing, carrying out second cold rolling by adopting a single-frame reversible six-roller mill, wherein the total cold rolling reduction is controlled to be 0.70-1.70 mm, and the total cold rolling reduction is controlled to be 30-85%, so that a cold-rolled wide steel strip with the width of 1000-1260 mm is obtained;
(13) and (3) second spheroidizing annealing: the steel strip after the second cold rolling is spheroidized by adopting a full-hydrogen strong convection hood-type annealing furnace, a low-temperature and high-temperature alternative spheroidizing annealing process is adopted in a heat preservation section, after heat preservation is finished, the steel strip is cooled to 500-600 ℃ along with the furnace, a cooling hood is replaced for air cooling, the steel strip is cooled to 280-340 ℃, water is sprayed and cooled to 80-100 ℃ for discharging, the Vickers hardness HV5 is below 175, and the spheroidization rate is more than 94%;
(14) and (3) cold rolling for the third time: and after the second spheroidizing annealing, carrying out third cold rolling by adopting a single-frame reversible six-roller mill, wherein the total cold rolling reduction is controlled to be 0.40-1.00 mm, and the total cold rolling reduction is controlled to be 50-85%, so that the wide cold-rolled steel strip with the specification of 0.10-0.70 mm, the thickness and the width of 1000-1260 mm is obtained.
7. The manufacturing process of the high-carbon tool steel SK85 cold-rolled wide steel strip as claimed in claim 6 is characterized by comprising the following steps:
(1) smelting in a converter: conventionally smelting by adopting a top-bottom combined blown converter;
(2) refining in an LF furnace: smelting in a converter and then refining in an LF furnace to obtain chemical components in the SK85 brand range set by JIS G4401;
(3) slab continuous casting: refining in an LF furnace, and then carrying out continuous casting, wherein the blank drawing speed is controlled to be 1.0-1.15 m/min, so that a continuous casting plate blank with the thickness of 210-230 mm and the width of 1000-1280 mm is obtained;
(4) heating: heating the continuous casting slab, and adopting a three-section type heating mode, wherein the temperature of a preheating section is controlled to be 630-730 ℃, the temperature of a first heating section is controlled to be 1080-1130 ℃, the temperature of a second heating section is controlled to be 1180-1230 ℃, the temperature of a soaking section is controlled to be 1170-1230 ℃, and the furnace time is controlled to be 150-180 min;
(5) hot continuous rolling: carrying out hot continuous rolling on the heated continuous casting plate blank, and controlling the finish rolling temperature to be 840-870 ℃;
(6) laminar cooling: carrying out laminar cooling on the hot-rolled steel strip, controlling the cooling speed to be 30-55 ℃/s, and cooling to the coiling temperature;
(7) coiling: cooling the hot rolled steel strip, coiling, and controlling the coiling temperature to be 630-660 ℃ to obtain a hot rolled wide steel strip with the specification of 2.5-6.0 mm thickness and the width of 1000-1260 mm;
(8) and (4) warehousing and slow cooling: the coiled hot-rolled wide steel strip is put in a warehouse for slow cooling, the hot-rolled wide steel strip is hung into a pit type special slow cooling device for slow cooling treatment, and the steel strip is naturally cooled to room temperature, so that the obtained metallographic structure is fine lamellar pearlite;
(9) acid washing: slowly cooling to room temperature, and then pickling the hot-rolled wide steel strip, wherein the pickling speed is controlled to be 96-126 m/min, and the acid liquor temperature of an acid tank is controlled to be 68-78 ℃;
(10) first cold rolling: after acid washing, cold rolling is carried out by adopting a single-frame reversible six-roller mill, the total cold rolling reduction is controlled to be 0.56-1.45 mm, and the total cold rolling reduction is controlled to be 24-48%;
(11) first spheroidizing annealing: the steel strip after the first cold rolling is spheroidized by adopting a full-hydrogen strong convection hood-type annealing furnace, and the heat preservation section adopts a low-temperature and high-temperature alternative spheroidizing annealing process; after heat preservation is finished, cooling to 535-585 ℃ along with the furnace, changing a cooling cover for air cooling, cooling to 300-325 ℃, spraying water, cooling to 83-97 ℃, discharging, wherein the Vickers hardness HV5 is below 175, and the nodularity is more than 93%;
(12) and (3) second cold rolling: after the first spheroidizing annealing, carrying out second cold rolling by adopting a single-frame reversible six-roller mill, wherein the total cold rolling reduction is controlled to be 0.75-1.65 mm, and the total cold rolling reduction is controlled to be 35-80%, so that a cold-rolled wide steel strip with the width of 1000-1260 mm is obtained;
(13) and (3) second spheroidizing annealing: the steel strip after the second cold rolling is spheroidized by adopting a full-hydrogen strong convection hood-type annealing furnace, and the heat preservation section adopts a low-temperature and high-temperature alternative spheroidizing annealing process; after the heat preservation is finished, cooling to 515-590 ℃ along with the furnace, changing a cooling cover for air cooling, cooling to 297-317 ℃, spraying water and cooling to 82-94 ℃ to discharge, wherein the Vickers hardness HV5 is below 170, and the nodularity is above 95%;
(14) and (3) cold rolling for the third time: and after the second spheroidizing annealing, carrying out third cold rolling by adopting a single-frame reversible six-roller mill, wherein the total cold rolling reduction is controlled to be 0.45-1.00 mm, and the total cold rolling reduction is controlled to be 53-85%, so that the wide cold-rolled steel strip with the specification of 0.10-0.70 mm, the thickness and the width of 1000-1260 mm is obtained.
8. The manufacturing process of the high-carbon tool steel SK85 cold-rolled wide steel strip as claimed in claim 6, wherein the chemical composition of the steel in the step (2) is as follows by mass percent: c: 0.82 to 0.88%, Si: 0.12 to 0.28%, Mn: 0.25-0.45%, P is less than or equal to 0.025%, S is less than or equal to 0.010%, Cr is less than or equal to 0.05%, Ni is less than or equal to 0.05%, Cu is less than or equal to 0.05%, and the balance of Fe and inevitable impurity elements.
9. The manufacturing process of the high-carbon tool steel SK85 cold-rolled wide steel strip as claimed in claim 7, wherein the chemical composition of the steel of step (2) is as follows by mass percent: c: 0.83 to 0.86%, Si: 0.15 to 0.25%, Mn: 0.30-0.40 percent of P, less than or equal to 0.020 percent of S, less than or equal to 0.006 percent of S, less than or equal to 0.03 percent of Cr, less than or equal to 0.03 percent of Ni, less than or equal to 0.04 percent of Cu, and the balance of Fe and inevitable impurity elements.
10. The manufacturing process of the high-carbon tool steel SK85 cold-rolled wide steel strip as claimed in claim 6 or 7, wherein the heat-preservation section low-temperature and high-temperature alternative spheroidizing annealing process is as follows: heating the cold-rolled steel strip → heating up to 640-680 ℃ for 3-4 hours → heating up to 700-730 ℃ for 4-6 hours → cooling down to 640-680 ℃ for 3-4 hours.
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