CN115572891B - Cold-rolled annealed steel strip with yield strength of 420MPa for art knife blade - Google Patents
Cold-rolled annealed steel strip with yield strength of 420MPa for art knife blade Download PDFInfo
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- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
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- C21—METALLURGY OF IRON
- 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
- 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
- C21D8/0205—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips of ferrous alloys
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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
- 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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- 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
- 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
- C21D8/0247—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment
- C21D8/0263—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment following hot rolling
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- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
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- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
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- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
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- C21—METALLURGY OF IRON
- 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
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/005—Ferrite
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- 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
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/009—Pearlite
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Abstract
The invention discloses a cold-rolled annealed steel strip with 420 MPa-grade yield strength for an art knife blade, which solves the technical problems of low hardness and high manufacturing cost of the existing cold-rolled annealed steel strip for the art knife blade. The technical scheme is that the cold-rolled annealed steel strip with the yield strength of 420MPa for the art knife blade comprises the following chemical components in percentage by weight: c:0.90% -0.98%, si:0.10 to 0.30 percent of Mn:0.30 to 0.50 percent, P is less than or equal to 0.015 percent, S is less than or equal to 0.003 percent, cr:0.10 to 0.30 percent of Al:0.02% -0.04%, N is less than or equal to 0.0060%, and the balance is Fe and unavoidable impurities; the grade of nonmetallic inclusion in the cold-rolled annealed steel strip is below 1.5 grade. Yield strength R of cold-rolled annealed steel strip with thickness of 0.30-0.60mm P0.2 Is 420-480 MPa and is used for manufacturing high-strength art designing blades.
Description
Technical Field
The invention relates to a cold-rolled annealed steel strip for manufacturing a machining cutter, in particular to a cold-rolled annealed steel strip with yield strength of 420MPa for an art knife blade and a manufacturing method thereof, and belongs to the technical field of iron-based alloy.
Background
The art knife is commonly called as a nicking knife or a wallpaper knife, is a knife for art and handicraft, is mainly used for cutting soft things, and is mainly composed of a plastic knife handle and a knife blade, and is of a drawing type structure. The cutter body is required to have high strength and hardness and a certain brittleness, but is required to have good toughness during forming processing, so that brittle fracture during press forming is prevented.
The hardness and the durability of the cutter body of the art designing cutter are different due to different cutter body materials, the conventional art designing cutter blade is generally made of 50 steel or 65Mn at present, but the hardness of the cutter blade after heat treatment of the cutter blade by the steel is less than or equal to 55HRC, the hardness is low, and the service life is short.
The patent application with the publication number of CN106077087A discloses a strip rolling process method and production equipment special for art designing blades, the patent discloses a process of rolling strip steel by adopting a 20-roller cold rolling mill, the equipment and flow arrangement of the cold rolling mill are described in an important mode, key process parameters are not described, the tissue control and requirements of materials are not described, the adopted raw materials are common 50 steel, 65Mn and other conventional steel types, the hardness of the cutter after heat treatment can only reach 52-55HRC, the hardness of the material is lower, and the service life of the material is lower.
The patent application with publication number of CN 105543646A discloses a production process of high-carbon steel in a sheet billet, which comprises the following main chemical elements in percentage by weight: 0.5 to 0.88 percent of carbon, 0.15 to 0.68 percent of silicon, 0.65 to 1.55 percent of manganese, 0.09 to 0.22 percent of chromium, 0.08 to 0.12 percent of nickel, 0.02 to 0.035 percent of arsenic, 0.18 to 0.20 percent of copper, less than or equal to 0.2 percent of aluminum, less than or equal to 0.025 percent of phosphorus, 0.002 to 0.0025 percent of sulfur, and the balance of Fe and unavoidable impurities; the invention adopts a thin slab continuous casting and rolling equipment process for improving the center segregation and surface cracks of materials, and discloses the thin slab continuous casting process and parameters.
Disclosure of Invention
The invention aims to provide a cold-rolled annealed steel strip with 420 MPa-grade yield strength for an art knife blade and a manufacturing method thereof, which solve the technical problems of low hardness and high manufacturing cost of the existing cold-rolled annealed steel strip for the art knife blade.
The invention adopts a component design method for improving the content of a C element matrix in steel and effectively adding a certain amount of Mn and Cr microalloy elements, adopts LF+RH double refining to control harmful elements and inclusions in the steel, and combines a hot rolling process to regulate and control a hot rolling state pearlite structure; and finally, the structure and performance of the material are improved through multipass cold rolling and spheroidizing annealing in a hood-type annealing furnace, and the cold-rolled annealed steel strip for the high-strength art knife blade is obtained.
The technical scheme of the invention is that the cold-rolled annealed steel strip with the yield strength of 420MPa for the art knife blade comprises the following chemical components in percentage by weight: c:0.90% -0.98%, si:0.10 to 0.30 percent of Mn:0.30 to 0.50 percent, P is less than or equal to 0.015 percent, S is less than or equal to 0.003 percent, cr:0.10 to 0.30 percent of Al:0.02% -0.04%, N is less than or equal to 0.0060%, and the balance is Fe and unavoidable impurities; the grade of nonmetallic inclusion in the cold-rolled annealed steel strip is below 1.5 grade.
Cold rolling annealing of the inventionThe metallographic structure of the fire steel strip is granular pearlite and ferrite, and the spheroidization rate is 90-95%; yield strength R of cold-rolled annealed steel strip with thickness of 0.30-0.60mm P0.2 420-480 MPa, tensile strength R m 560-620 MPa, elongation after break A 50mm 20% -25%; the Vickers hardness HV0.5 is 175-195.
The cold-rolled annealed steel strip is subjected to heat treatment by adopting a quenching and tempering process, and the Rockwell hardness of the cold-rolled annealed steel strip after heat treatment is 60-63 HRC.
The reason why the chemical components of the cold-rolled annealed steel strip with the yield strength of 420MPa for the art knife blade are limited in the above range is as follows:
carbon: carbon is the primary alloying element of pearlite formation and affects the hardness of the material after hot rolling, cold rolling, annealing and quenching of the blade. The content of C is too low to meet the final high-hardness requirement of the part; if the content of C is too high, the plastic toughness is obviously reduced, and the steel coil is brittle broken. By comprehensive consideration, the carbon content is set to be 0.90% -0.98%.
Silicon: silicon is used as a solid solution strengthening element, has a certain strengthening effect when being dissolved in a steel belt matrix, and simultaneously is used as a deoxidizer during smelting to play roles in deoxidization and desulfurization. However, when the ferrite phase is contained in a large amount, the ferrite phase is hardened, and the workability is significantly deteriorated. Si promotes the generation of rust red oxide scale defects on the surface of the steel coil in the hot rolling process, and influences the appearance of a finished product; by comprehensive consideration, the Si content is set to be 0.10% -0.30%.
Manganese: manganese is a good deoxidizer and desulfurizing agent. The steel contains a certain amount of manganese, so that the hot workability of the steel can be eliminated or improved, and meanwhile, the hardenability can be obviously improved. However, when the content is too large, segregation of components is caused, and the structure becomes uneven, and the molding property of the material is drastically lowered. Through comprehensive consideration, the Mn content is set to be 0.30% -0.50%.
Phosphorus: phosphorus is an impurity element, segregates in grain boundaries to lower workability, and it is desired to reduce the content as much as possible to improve formability; however, in view of the process equipment control capacity and dephosphorization cost, the invention limits P to less than or equal to 0.015%.
Sulfur: sulfur is an impurity element, and forms inclusions such as MnS in steel, which affects formability. It is desirable to reduce the content thereof as much as possible; in consideration of actual control capability and desulfurization cost, S is limited to be less than or equal to 0.003 percent.
Chromium: chromium is a carbide forming element that can form a variety of alloy carbides; and suppresses grain size of the structure in the cooling process after hot rolling, improves strength and hardness of the material, and generally requires a content of 0.10% or more, but excessive content increases alloy cost and also reduces workability. By comprehensive consideration, the invention sets the Cr content to be 0.10-0.30%.
Aluminum: the role of aluminum in the present invention is to deoxidize and bind free nitrogen, aluminum is a strong oxidizing forming element, and oxygen in steel forms Al 2 O 3 Removed during steelmaking. Meanwhile, aluminum also has the effects of refining grains and preventing coarse austenite grains, and the effects are obviously reduced along with the increase of the aluminum content; at the same time, too high aluminum will form too much Al 2 O 3 The inclusion is easy to block the pouring nozzle during continuous casting pouring. By comprehensive consideration, the Al content is set to be 0.02% -0.04%.
Nitrogen: too high a nitrogen content seriously deteriorates the plasticity and toughness of the material, increases the brittleness of the steel, and also causes cracking of the continuous casting billet. The invention limits N to less than or equal to 0.0060 percent.
A method for manufacturing a cold-rolled annealed steel strip with 420 MPa-grade yield strength for an art knife blade, comprising the following steps:
the molten steel is refined by an LF refining furnace and subjected to vacuum degassing treatment by an RH furnace, and then continuous casting is carried out to obtain a continuous casting slab, wherein the continuous casting slab comprises the following chemical components in percentage by weight: c:0.90 to 0.98 percent, si:0.10 to 0.30 percent, mn:0.30 to 0.50 percent, P is less than or equal to 0.015 percent, S is less than or equal to 0.003 percent, cr:0.10 to 0.30 percent of Al:0.02 to 0.04 percent, N is less than or equal to 0.0060 percent; the balance of Fe and unavoidable impurities; according to the American society for testing and materials ASTM E45-13 standard test method for determining inclusion content in steel, method A is adopted for testing, and the nonmetallic inclusion grade in a continuous casting slab is below grade 1.5;
heating a continuous casting slab to 1190-1230 ℃ by a heating furnace, and then carrying out hot rolling for 180-240 min, wherein the hot rolling is a two-stage rolling process, rough rolling is 5-pass continuous rolling, rolling is carried out above austenite recrystallization temperature, and the initial rolling finishing temperature is 1020-1060 ℃; the finish rolling is 7-pass continuous rolling, the finish rolling finishing temperature is 870-910 ℃, and the finish rolling reduction rate is 90-95%; after finish rolling, controlling the thickness of the steel plate to be 2.0-3.0 mm, adopting front-stage cooling for laminar cooling, wherein the cooling speed is 20-30 ℃/S, and the coiling temperature is 620-660 ℃ to coil to obtain a hot rolled steel coil;
transferring the hot rolled steel coil to a slow cooling area, slowly cooling the hot rolled steel coil by using a slow cooling wall, and after the hot rolled steel coil is slowly cooled for 48-72 hours, moving the hot rolled steel coil out of the slow cooling area for air cooling;
after the hot rolled steel coil is uncoiled again, carrying out acid washing, strip separation, cold rolling and annealing by a hood-type annealing furnace to obtain a finished cold-rolled annealed steel strip with the thickness of 0.30-0.60mm, wherein the cold rolling reduction rate is 75-85%; the rolled hard steel strip after cold rolling is annealed by a hood-type annealing furnace, the temperature of the steel strip in the soaking section of the hood-type annealing furnace is 700-720 ℃, and the annealing time of the steel strip in the soaking section is 14-16h.
The hot rolling process and the control of the structure of the hot rolled steel coil are one of the key points of the technology for realizing the invention. By calculation, the component system A of the invention cm 824.8 ℃, A 1 733.2 ℃; the hot rolling process adopted is based on the component system and calculated phase change point.
The reason of the production process system adopted by the invention is as follows:
1. setting of inclusion grade in molten steel by adopting LF refining furnace and RH vacuum furnace double refining process and continuous casting slab
The control of nonmetallic inclusion in molten steel is a key technology for realizing the invention, because the thickness of the art designing blade is very thin and only 0.3-0.6mm thick, the size and shape of nonmetallic inclusion in the steel greatly affect the processing of the art designing blade, and the excessive inclusion can cause microcrack and even cracking of the shaping processing of the art designing blade, so that the product is invalid. Therefore, in the steelmaking refining process, the LF refining furnace and the RH vacuum furnace are adopted for double refining, the inclusion grade in the continuous casting slab is controlled and controlled, the inclusion grade in the continuous casting slab is checked according to the standard test method for determining the inclusion content in steel by American society for testing and materials ASTM E45-13, and the method A is adopted for testing, so that the nonmetallic inclusion grade in the continuous casting slab is set to be below 1.5 grade, and the forming and processing requirements of an art designing blade are met.
2. Setting of heating temperature and heating time of continuous casting slab
The heating temperature and time of the continuous casting slab are set to ensure that alloy elements such as C, si, mn and the like in the continuous casting slab are fully diffused and dissolved, and coarse carbide particles are dissolved and uniformly distributed in steel. The above object cannot be achieved by too low a temperature and too short a heating time. The higher slab heating temperature is adopted, the target temperature is 1210 ℃, if the target temperature is too high, the heating time is too long, the surface oxidation and decarburization of the slab are serious, the final performance and the surface quality of the steel strip are not facilitated, and meanwhile, the energy is consumed. Therefore, the heating temperature of the continuous casting slab is 1190-1230 ℃ and the heating time is 180-240 min.
3. Setting of finish finishing temperature
The finish rolling temperature setting has two functions, namely, on one hand, flat austenite grains with deformation bands inside are obtained by rolling the material in an austenite non-recrystallization region, and the flat austenite grains are transformed into fine ferrite grains in the subsequent laminar cooling process, so that the grains are refined, and the band segregation is relieved; on the other hand, if the finishing temperature is too low, the rolling load becomes too large, and the rolling stability is affected. Therefore, the finishing temperature of the finish rolling is set to 870-910 ℃.
4. Laminar cooling method and setting of cooling rate
The laminar cooling after finish rolling adopts a front-stage cooling process, can promote the austenite structure in the material after finish rolling to quickly generate pearlite transformation, and ensures that the structure is uniform and moderately refined, so the cooling speed is set to 20-30 ℃/S.
5. Setting of hot rolling coiling temperature
The hot rolling coiling temperature mainly influences the structure and performance of the material and the subsequent spheroidizing annealing effect. The moderate coiling temperature is adopted, so that the crystal grains can be moderately refined and uniform, and the subsequent cold rolling is facilitated. If the coiling temperature is too high, the crystal grains are coarse and the structure is uneven, if the coiling temperature is too low, the strength of the hot rolled material is obviously increased, the brittleness of the steel coil is increased, and further uncoiling and splitting and cold rolling processing are not facilitated. Therefore, the hot rolling coiling temperature is set to 620-660 ℃.
6. Setting of slow cooling time of hot rolled steel coil in slow cooling zone
The hot rolled steel coil enters a slow cooling wall after being coiled, and mainly prevents the steel coil from being cooled too fast after being coiled and from generating martensite-like transformation. Because the carbon content of the product is very high, bainite and even martensite transformation can be generated in the open stacking and air cooling process of the steel coil, so that the brittleness of the material is obviously increased, the problem of local cracking and belt breakage occurs, and the subsequent processing is influenced. Therefore, the steel coil after hot rolling enters a slow cooling wall for cooling, and the slow cooling time is set to be 48-72 hours.
7. Setting of cold rolling reduction
The cold rolling deformation is an important means for improving the hardness and the specification and dimension precision of the steel strip. Along with the continuous increase of the cold rolling deformation, the dislocation density in the material is greatly increased, and more energy is provided for the spheroidization transformation of the lamellar pearlite. However, an excessively high deformation amount causes an excessively large load on the cold rolling mill, increases the cold rolling pass, and greatly increases the cold rolling cost. In the present invention, the cold rolling reduction is preferably 75 to 85%.
8. Setting of annealing temperature and annealing time
The invention adopts a hood-type annealing furnace for annealing, considers the accumulated effect of cold rolling deformation in the previous working procedure, promotes the spheroidization of flaky pearlite, and is generally shown in A 1 Annealing is performed below the spot temperature. The annealing temperature of the steel strip in the soaking section of the hood-type annealing furnace is 700-720 ℃.
The heat preservation time of the soaking section is also critical during annealing; if the heat preservation time is too short, the lamellar pearlite chain cannot be completely fused and broken; fine spherical particles cannot be generated, and dispersion distribution is formed; if the heat preservation time is too long, the granular pearlite can grow again and agglomerate together, and form lamellar segregation, so that the toughness of the material is reduced, and the subsequent processing is not facilitated. In order to improve the spheroidizing annealing effect, the setting time of the steel strip in the soaking section is 14-16h.
The metallographic structure of the hot rolled steel strip is fine flake pearlite; yield strength R of hot rolled steel strip with thickness of 2.0-3.0 mm P0.2 600-700 MPa, tensile strength R m 950-1100 MPa, elongation after break A 50mm 12 to 18 percent.
The metallographic structure of the cold-rolled annealed steel strip produced by the method is granular pearlite and ferrite, and the spheroidization rate is 90-95%; yield strength R of cold-rolled annealed steel strip with thickness of 0.30-0.60mm P0.2 420-480 MPa, tensile strength R m 560-620 MPa, elongation after break A 50mm 20% -25%; the Vickers hardness HV0.5 is 175-195.
The cold-rolled annealed steel strip is subjected to heat treatment by the conventional quenching and tempering process, and the Rockwell hardness of the cold-rolled annealed steel strip after heat treatment is 60-63 HRC.
Compared with the prior art, the invention has the following positive effects: 1. the invention improves the hardness of the material by adopting high carbon content in component design; meanwhile, a certain amount of microalloy elements such as Mn, cr and the like are added to improve the quenching performance of the material, so that the high-hardness cold-rolled annealed steel strip is obtained; the cold-rolled annealed steel strip is subjected to heat treatment by the conventional quenching and tempering process, and the Rockwell hardness of the cold-rolled annealed steel strip after heat treatment is 60-63 HRC. 2. In the material manufacturing process, the invention adopts LF+RH double refining to control the content of harmful elements and inclusions in steel in the steelmaking process, and the hot rolling process controls the rolling temperature and the cooling mode after rolling to obtain a hot rolled steel coil with moderately refined grains and moderate strength and toughness. And through multipass cold rolling and reasonable annealing processes, the flaky pearlite in the steel is fully spheroidized, so that the cold-rolled steel strip for the art knife blade with evenly distributed structure is obtained, and the shaping and final heat treatment performance of the knife blade are facilitated.
Drawings
FIG. 1 is a photograph showing a metallographic structure of a hot rolled steel strip according to example 3 of the invention, which is 500 times magnified.
FIG. 2 is a photograph showing a metallographic structure of a cold-rolled annealed steel strip according to example 3 of the present invention, which is 500 times magnified.
Detailed Description
The present invention will be further described with reference to examples 1 to 5, as shown in tables 1 to 5.
Table 1 shows the chemical composition (in weight percent) of the steels of the examples of the invention, the balance Fe and unavoidable impurities.
Table 1 chemical composition of the steel according to the example of the invention, unit: weight percent,%.
Smelting in a converter, desulfurizing in an LF ladle refining furnace, refining alloy components in a fine-tuning mode and performing vacuum circulation degassing in an RH furnace, wherein the pure degassing time is longer than 8 minutes, molten steel meeting component requirements is obtained, and a continuous casting slab is obtained through continuous casting of the molten steel. The thickness of the continuous casting slab is 210-230 mm, the width is 900-1600 mm, and the length is 8000-11700 mm.
The method provided by the invention is used for obtaining the continuous casting slab, the inclusion is detected according to the non-metallic inclusion evaluation method (GB/T10561) in the steel, and the grade of the non-metallic inclusion in the continuous casting slab is below 1.5 grade.
Directly hot-charging the continuous casting slab, sending the continuous casting slab to a heating furnace for heating, and cooling the middle part without off-line cooling; and (5) discharging the steel and removing scales, and then conveying the steel to a hot continuous rolling unit for rolling. Rolling is controlled by a rough rolling mill unit and a finish rolling mill unit, rolling is performed after laminar cooling, the laminar cooling adopts front-stage cooling, and qualified hot rolled steel coils are produced, and the thickness of the hot rolled steel strip is 2.0-3.0 mm.
Transferring the hot rolled steel coil to a slow cooling area, slowly cooling the hot rolled steel coil by using a slow cooling wall, slowly cooling for 48-72 hours, and then removing the hot rolled steel coil from the slow cooling area for air cooling. The hot rolling process control parameters are shown in Table 2.
The hot rolled steel strip obtained by the above method, referring to fig. 1, the metallographic structure of the hot rolled steel strip is fine-flake pearlite; bending of hot rolled steel strip with thickness of 2.0-3.0 mmIntensity of clothing R P0.2 600-700 MPa, tensile strength R m 950-1100 MPa, elongation after break A 50mm 12 to 18 percent.
The hot rolled steel strip obtained by the invention is subjected to a tensile test according to GB/T228.1-2010 section 1: room temperature test method tensile test was performed and the microstructure of the steel was examined by the microstructure assessment method (GB/T13299) and the mechanical properties thereof are shown in table 3.
TABLE 2 Hot Rolling Process parameters according to the examples of the invention
TABLE 3 mechanical Properties of the Hot rolled Steel strip according to the example of the invention
The hot rolled steel coil is uncoiled again and then is pickled, and after being striped according to the width specification, the hot rolled steel coil is subjected to multi-pass cold rolling on a reversible rolling mill or a single-stand cold rolling mill, wherein the cold rolling reduction is 75-85%; the rolled hard steel coil after cold rolling is annealed by a bell-type furnace to obtain a finished cold-rolled steel strip with the thickness of 0.30-0.60mm, and the spheroidizing annealing process comprises the following steps: the annealing (soaking period) temperature of the bell-type furnace is 700-720 ℃, and the annealing (soaking period) time is 14-16h. The control parameters of the cold rolling and annealing processes are shown in Table 4.
TABLE 4 control parameters of the cold rolling and annealing processes according to the embodiment of the invention
| Parameters of cold rolling and annealing | Cold rolling reduction/% | Annealing temperature/. Degree.C | Annealing time/h | Thickness/mm of cold-rolled steel strip |
| The invention is that | 75-85 | 700-720 | 14-16 | 0.30-0.60 |
| Example 1 | 82.6 | 715 | 15.0 | 0.40 |
| Example 2 | 85.0 | 710 | 14.5 | 0.30 |
| Example 3 | 84.0 | 705 | 15.0 | 0.40 |
| Example 4 | 79.5 | 710 | 16.0 | 0.55 |
| Example 5 | 84.0 | 720 | 14.5 | 0.35 |
The cold-rolled annealed steel strip obtained by the method is shown in fig. 2, the metallographic structure of the cold-rolled annealed steel strip is granular pearlite and ferrite, and the spheroidization rate is 90-95%; yield strength R of cold-rolled annealed steel strip with thickness of 0.30-0.60mm P0.2 420-480 MPa, tensile strength R m 560-620 MPa, elongation after break A 50mm 20% -25%; the Vickers hardness HV0.5 is 175-195.
The cold-rolled annealed steel strip obtained by the invention is subjected to stretching, microstructure and hardness detection according to a metal material stretching test method (GB/T228.1), a steel microstructure evaluation method (GB/T13299) and a metal material Vickers hardness test method (GB/T4340.1-2009), and the mechanical properties of the cold-rolled annealed steel strip are shown in Table 5.
TABLE 5 Performance index of the cold-rolled annealed strip according to the embodiment of the invention
The cold-rolled annealed steel strip of the invention is subjected to heat treatment by the conventional quenching and tempering process, and hardness detection is carried out according to the Rockwell hardness test method (GB/T230.1-2009) of the metal material, wherein the Rockwell hardness of the cold-rolled annealed steel strip of the examples 1-5 after the quenching and tempering heat treatment is 61.5HRC, 62.5HRC, 61.0HRC, 60.5HRC and 62.0HRC respectively.
As shown in Table 5, the cold-rolled annealed steel strip has good material toughness and higher hardness after quenching and tempering heat treatment; meets the use requirements of continuous forming processing and high hardness of the art designer blade.
In addition to the above embodiments, the present invention may have other embodiments; all technical schemes formed by equivalent substitution or equivalent transformation fall within the protection scope of the invention.
Claims (6)
1. A cold-rolled annealed steel strip with 420 MPa-grade yield strength for art knife blade comprises the following chemical components in percentage by weight: c:0.90% -0.98%, si:0.10 to 0.30 percent of Mn:0.30 to 0.50 percent, P is less than or equal to 0.015 percent, S is less than or equal to 0.003 percent, cr:0.10 to 0.30 percent of Al:0.02% -0.04%, N is less than or equal to 0.0060%, and the balance is Fe and unavoidable impurities; the grade of nonmetallic inclusion in the cold-rolled annealed steel strip is below 1.5 grade; yield strength R of cold-rolled annealed steel strip with thickness of 0.30-0.60mm P0.2 420-480 MPa, tensile strength R m 560-620 MPa, elongation after break A 50mm 20% -25%; the Vickers hardness HV0.5 is 175-195; the manufacturing method of the cold-rolled annealed steel strip comprises the following steps:
the molten steel is refined by an LF refining furnace and subjected to vacuum degassing treatment by an RH furnace, and then continuous casting is carried out to obtain a continuous casting slab, wherein the continuous casting slab comprises the following chemical components in percentage by weight: c:0.90 to 0.98 percent, si:0.10 to 0.30 percent, mn:0.30 to 0.50 percent, P is less than or equal to 0.015 percent, S is less than or equal to 0.003 percent, cr:0.10 to 0.30 percent of Al:0.02 to 0.04 percent, N is less than or equal to 0.0060 percent; the balance of Fe and unavoidable impurities; according to the standard test method for determining the content of inclusions in steel by American society for testing materials, ASTME45-13, the method A is adopted for testing, and the grade of nonmetallic inclusion in a continuous casting slab is below grade 1.5;
heating a continuous casting slab to 1190-1230 ℃ by a heating furnace, and then carrying out hot rolling for 180-240 min, wherein the hot rolling is a two-stage rolling process, rough rolling is 5-pass continuous rolling, rolling is carried out above austenite recrystallization temperature, and the initial rolling finishing temperature is 1020-1060 ℃; the finish rolling is 7-pass continuous rolling, the finish rolling finishing temperature is 870-910 ℃, and the finish rolling reduction rate is 90-95%;
after finish rolling, controlling the thickness of the steel plate to be 2.0-3.0 mm, adopting front-stage cooling for laminar cooling, wherein the cooling speed is 20-30 ℃/S, and the coiling temperature is 620-660 ℃ to coil to obtain a hot rolled steel coil;
transferring the hot rolled steel coil to a slow cooling area, entering a slow cooling wall to slowly cool the hot rolled steel coil, and moving the hot rolled steel coil out of the slow cooling area after slowly cooling for 48-72 hours;
after the hot rolled steel coil is uncoiled again, carrying out acid washing, strip separation, cold rolling and annealing by a hood-type annealing furnace to obtain a finished cold-rolled annealed steel strip with the thickness of 0.30-0.60mm, wherein the cold rolling reduction rate is 75-85%; the rolled hard steel strip after cold rolling is annealed by a hood-type annealing furnace, the temperature of the steel strip in the soaking section of the hood-type annealing furnace is 700-720 ℃, and the annealing time of the steel strip in the soaking section is 14-16h.
2. The cold-rolled annealed strip of 420MPa grade yield strength for art blades according to claim 1, wherein the metallographic structure of the cold-rolled annealed strip is granular pearlite + ferrite and the spheroidization rate is 90-95%.
3. The cold-rolled annealed strip of 420MPa grade yield strength for art blades according to claim 1, wherein the cold-rolled annealed strip has a rockwell hardness of 60-63 HRC after heat treatment by a quenching and tempering process.
4. The manufacturing method of the cold-rolled annealed steel strip with the yield strength of 420MPa for the art knife blade is characterized by comprising the following steps:
the molten steel is refined by an LF refining furnace and subjected to vacuum degassing treatment by an RH furnace, and then continuous casting is carried out to obtain a continuous casting slab, wherein the continuous casting slab comprises the following chemical components in percentage by weight: c:0.90 to 0.98 percent, si:0.10 to 0.30 percent, mn:0.30 to 0.50 percent, P is less than or equal to 0.015 percent, S is less than or equal to 0.003 percent, cr:0.10 to 0.30 percent of Al:0.02 to 0.04 percent, N is less than or equal to 0.0060 percent; the balance of Fe and unavoidable impurities; according to the standard test method for determining the content of inclusions in steel by American society for testing materials, ASTME45-13, the method A is adopted for testing, and the grade of nonmetallic inclusion in a continuous casting slab is below grade 1.5;
heating a continuous casting slab to 1190-1230 ℃ by a heating furnace, and then carrying out hot rolling for 180-240 min, wherein the hot rolling is a two-stage rolling process, rough rolling is 5-pass continuous rolling, rolling is carried out above austenite recrystallization temperature, and the initial rolling finishing temperature is 1020-1060 ℃; the finish rolling is 7-pass continuous rolling, the finish rolling finishing temperature is 870-910 ℃, and the finish rolling reduction rate is 90-95%;
after finish rolling, controlling the thickness of the steel plate to be 2.0-3.0 mm, adopting front-stage cooling for laminar cooling, wherein the cooling speed is 20-30 ℃/S, and the coiling temperature is 620-660 ℃ to coil to obtain a hot rolled steel coil;
transferring the hot rolled steel coil to a slow cooling area, entering a slow cooling wall to slowly cool the hot rolled steel coil, and moving the hot rolled steel coil out of the slow cooling area after slowly cooling for 48-72 hours;
after the hot rolled steel coil is uncoiled again, carrying out acid washing, strip separation, cold rolling and annealing by a hood-type annealing furnace to obtain a finished cold-rolled annealed steel strip with the thickness of 0.30-0.60mm, wherein the cold rolling reduction rate is 75-85%; the rolled hard steel strip after cold rolling is annealed by a hood-type annealing furnace, the temperature of the steel strip in the soaking section of the hood-type annealing furnace is 700-720 ℃, and the annealing time of the steel strip in the soaking section is 14-16h.
5. The method for producing a cold-rolled annealed steel strip having a yield strength of 420MPa grade for an art knife according to claim 4, wherein the metallographic structure of the cold-rolled annealed steel strip is granular pearlite+ferrite, and the spheroidization rate is 90 to 95%; yield strength R of cold-rolled annealed steel strip with thickness of 0.30-0.60mm P0.2 420-480 MPa, tensile strength R m 560-620 MPa, elongation after break A 50mm 20% -25%; the Vickers hardness HV0.5 is 175-195.
6. The method for manufacturing a cold-rolled annealed steel strip having a yield strength of 420MPa grade for an art-cutting insert according to claim 4, wherein the cold-rolled annealed steel strip has a rockwell hardness of 60 to 63HRC after heat treatment by a quenching and tempering process.
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