CN117123621A - Hot rolled steel strip for garden tool, preparation method and application thereof - Google Patents

Hot rolled steel strip for garden tool, preparation method and application thereof Download PDF

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Publication number
CN117123621A
CN117123621A CN202310911417.2A CN202310911417A CN117123621A CN 117123621 A CN117123621 A CN 117123621A CN 202310911417 A CN202310911417 A CN 202310911417A CN 117123621 A CN117123621 A CN 117123621A
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China
Prior art keywords
steel strip
hot rolled
rolled steel
garden tool
rolling
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Pending
Application number
CN202310911417.2A
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Chinese (zh)
Inventor
杨雄
张保忠
鲁欣武
闫江辉
贾国军
葛允宗
金辉
唐辉
杨志强
吴红翔
王剑云
曹艳平
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Ningbo Iron and Steel Co Ltd
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Ningbo Iron and Steel Co Ltd
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Application filed by Ningbo Iron and Steel Co Ltd filed Critical Ningbo Iron and Steel Co Ltd
Priority to CN202310911417.2A priority Critical patent/CN117123621A/en
Publication of CN117123621A publication Critical patent/CN117123621A/en
Pending legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B1/00—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations
    • B21B1/22—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling plates, strips, bands or sheets of indefinite length
    • B21B1/24—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling plates, strips, bands or sheets of indefinite length in a continuous or semi-continuous process
    • B21B1/26—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling plates, strips, bands or sheets of indefinite length in a continuous or semi-continuous process by hot-rolling, e.g. Steckel hot mill
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B15/00—Arrangements for performing additional metal-working operations specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B3/00—Rolling materials of special alloys so far as the composition of the alloy requires or permits special rolling methods or sequences ; Rolling of aluminium, copper, zinc or other non-ferrous metals
    • B21B3/02—Rolling special iron alloys, e.g. stainless steel
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B37/00—Control devices or methods specially adapted for metal-rolling mills or the work produced thereby
    • B21B37/58—Roll-force control; Roll-gap control
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B37/00—Control devices or methods specially adapted for metal-rolling mills or the work produced thereby
    • B21B37/74—Temperature control, e.g. by cooling or heating the rolls or the product
    • 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
    • C21D11/00—Process control or regulation for heat treatments
    • C21D11/005—Process control or regulation for heat treatments for cooling
    • 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
    • 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
    • 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
    • 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
    • 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
    • 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
    • C21D8/0242—Flattening; Dressing; Flexing
    • 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
    • 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
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B15/00—Arrangements for performing additional metal-working operations specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills
    • B21B2015/0057—Coiling the rolled product
    • 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
    • C21D2211/005—Ferrite
    • 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
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/20—Recycling

Abstract

The application provides a hot rolled steel strip for a garden tool, a preparation method and application thereof, and relates to the technical field of metallurgy, wherein the preparation method of the hot rolled steel strip for the garden tool comprises the following steps: heating a casting blank obtained by molten steel continuous casting to obtain the casting blank; and (3) sequentially performing rough rolling, finish rolling, cooling, coiling and slow cooling on the heated casting blank to obtain the hot rolled steel strip for the garden tool, wherein the pass reduction rate is more than or equal to 18% and the final pass reduction rate is more than 14% in the rough rolling and/or the finish rolling process, the coiling temperature in the coiling process is 680-720 ℃, and the slow cooling time in the slow cooling process of the steel strip is more than or equal to 48%, wherein the hot rolled steel strip for the garden tool comprises 0.0012% -0.0020% of boron by mass. The hot rolled steel strip for the garden tool has good cold stamping performance and low production cost, and the steel strip has proper hardness and wear resistance after quenching and tempering treatment.

Description

Hot rolled steel strip for garden tool, preparation method and application thereof
Technical Field
The application relates to the technical field of metallurgy, in particular to a hot rolled steel strip for a garden tool, a preparation method and application thereof.
Background
The steel material is a relatively common material in garden tools, has the characteristics of high strength and corrosion resistance, and can be used for manufacturing scissors, spades and the like in the garden tools.
At present, the garden tools such as scissors, spades and the like are processed by water quenching and tempering after the ordinary 50# medium carbon steel, 55# medium carbon steel and the like are molded or oil quenching and tempering after the high carbon steel such as SK85 and the like is molded. While 50# and 55# medium carbon steel and SK85 high carbon steel belts have high strength, and an annealing process is needed to reduce the strength before cold stamping. The problems of insufficient hardness, uneven hardness and poor wear resistance of the medium carbon steel after heat treatment exist, while the high carbon steel heat treatment process window is relatively narrow, and improper operation is extremely easy to generate cracking defects and cracks. There is thus a strong need to develop a garden tool steel strip having a lower strength after hot rolling suitable for cold stamping and having a suitable hardenability to enhance the hardness after heat treatment.
Disclosure of Invention
The application solves the problems that the hot rolled steel strip of the garden tool produced by the prior art has high hot rolled strength, can be subjected to cold stamping after annealing treatment, and cannot meet at least one of the requirements of direct cold stamping or insufficient hardness, uneven hardness and poor wear resistance of the steel strip after heat treatment.
In order to solve the above problems, the present application provides a method for preparing a hot rolled steel strip for a gardening tool, comprising:
step S1: heating a casting blank obtained by molten steel continuous casting to obtain the casting blank;
step S2: and (3) sequentially performing rough rolling, finish rolling, cooling, coiling and slow cooling on the heated casting blank to obtain the hot rolled steel strip for the garden tool, wherein the pass reduction rate is more than or equal to 18% and the final pass reduction rate is more than 14% in the rough rolling and/or the finish rolling process, the coiling temperature in the coiling process is 680-720 ℃, and the slow cooling time in the slow cooling process of the steel strip is more than or equal to 48 hours, wherein the hot rolled steel strip for the garden tool comprises 0.0012% -0.0020% of boron by mass.
Optionally, in step S1, a step furnace is used to heat the casting blank, and at the end of the heat treatment, the surface temperature of the casting blank is 1200±20 ℃.
Optionally, in step S1, the casting blank is treated with high-pressure water after being discharged from the furnace to remove surface scale.
Optionally, during the rough rolling in step S2, the start rolling temperature is 1100±20 ℃, and the finish rolling temperature is >1050 ℃.
Optionally, during the finish rolling in the step S2, the initial rolling temperature is equal to or higher than 1050 ℃, and the final rolling temperature is 885-915 ℃.
Optionally, in step S2, the cooling mode is laminar water cooling and air cooling alternate cooling.
Compared with the prior art, the preparation method of the hot rolled steel strip for the garden tool, disclosed by the application, has the advantages that on one hand, the structure of the steel strip is ferrite and pearlite by controlling the rolling temperature after rolling and slow cooling after rolling, and the internal stress of the steel strip is reduced to ensure the cold stamping performance of the steel strip when the garden tool is prepared by cold stamping, on the other hand, the rolling reduction rate is controlled to refine the lamellar spacing of the pearlite, so that a good original structure is provided for heat treatment, the negative influence of the coarse structure on the heat treatment is reduced, and the hardenability of the steel strip is improved to obtain a hard phase structure such as bainite or martensite by adding a proper amount of hardenability element boron B into the steel strip component, so that the steel strip has the cold stamping performance, the hardness and the wear resistance after the heat treatment, the tensile strength 646MPa (corresponding hardness is HRB 92) of the steel strip for the hot rolled steel strip for the garden tool, the elongation is more than or equal to 21%, the steel strip has good strong plasticity, the hardness after stamping and hardening and tempering treatment is more than or equal to 52HRC, and the use requirement of the steel for the garden tool is met.
In order to solve the problems, the application also provides a hot rolled steel strip for a gardening tool, which is prepared by adopting the preparation method of the hot rolled steel strip for the gardening tool, and comprises the following components in percentage by mass: c:0.55% -0.60%, si is less than or equal to 0.10%, mn:0.50% -0.70%, als 0.010% -0.020%, B:0.0012% -0.0020% of Fe and unavoidable impurities as the rest.
Alternatively, the nominal thickness of the hot rolled steel strip for gardening tools is 4mm or 4.1mm, and the actual thickness is 4.03-4.11mm.
Optionally, the tensile strength of the hot rolled steel strip for gardening tools is 630-646MPa, and the elongation is 21-27%.
The hot rolled steel strip for the garden tool has good cold stamping performance, and the steel strip has proper hardness and wear resistance after quenching and tempering treatment, specifically, the tensile strength of the hot rolled steel strip for the garden tool is less than or equal to 646MPa (corresponding hardness is HRB 92), the elongation is more than or equal to 21%, the steel strip has good strong plasticity, the hot rolled steel strip is suitable for stamping treatment, and the hardness of the steel strip after stamping and quenching treatment is 52-56HRC, so that the use requirement of the steel for the garden is met.
In order to solve the problems, the application also provides an application of the hot rolled steel strip for the garden tool, the hot rolled steel strip for the garden tool is used for preparing the garden tool in a cold stamping mode, and the hardness of the garden tool after heat treatment is 52-56HRC.
The application of the hot rolled steel strip for a gardening tool of the present application is the same as the advantage of the hot rolled steel strip for a gardening tool with respect to the prior art, and will not be described in detail herein.
Drawings
FIG. 1 is a flowchart showing a method for producing a hot rolled steel strip for a garden tool in an embodiment of the present application.
Detailed Description
The technical solutions of the embodiments of the present application will be clearly and thoroughly described below with reference to the accompanying drawings.
The description of the term "some embodiments" means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the application. In this specification, schematic representations of the above terms do not necessarily refer to the same implementations or examples. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
As shown in fig. 1, an embodiment of the present application provides a method for preparing a hot rolled steel strip for a gardening tool, comprising:
step S1: obtaining a casting blank through molten steel continuous casting and heating treatment;
step S2: and (3) sequentially performing rough rolling, finish rolling, cooling, coiling and slow cooling on the heated casting blank to obtain the hot rolled steel strip for the garden tool, wherein the pass reduction rate is more than or equal to 18% and the final pass reduction rate is more than 14% in the rough rolling and/or the finish rolling process, the coiling temperature in the coiling process is 680-720 ℃, and the slow cooling time in the slow cooling process of the steel strip is more than or equal to 48 hours, wherein the hot rolled steel strip for the garden tool comprises 0.0012% -0.0020% of boron by mass.
Specifically, in this embodiment, when the steel strip is cooled and then enters the coiler to be coiled, in order to improve the stamping performance of the steel strip, the structure of the steel strip needs to be strictly controlled, and a hard phase such as bainite or martensite cannot appear, so the coiling temperature of the steel strip cannot be close to Bs or Ms and should be in the upper half part of the P-phase region, therefore, the coiling temperature is controlled to 680-720 ℃ in the coiling process, and the steel strip is subjected to slow cooling treatment after coiling, and the slow cooling time is more than or equal to 48 hours, thereby reducing the internal stress of the steel to ensure the cold stamping performance of the steel strip when a garden tool is prepared by cold stamping. In the present example, the specific embodiment of the annealing treatment is not limited, and in some preferred examples, the annealing treatment is performed in a pit, which is easy to implement.
In addition, the improvement of the pass reduction rate is beneficial to increasing the deformation penetration of the casting blank in the thickness direction, so that the deformation of the surface of the casting blank penetrates to the thickness center, the deformation non-uniformity in the thickness direction is reduced, and the uniformity of the tissue is improved; moreover, the relatively large pass reduction rate is beneficial to accumulating structural defects, providing enough driving force and nucleation points for phase transformation and refining grains, so that the pass reduction rate is controlled to be more than or equal to 18% in the rough rolling and/or the finish rolling process in the embodiment; however, the final pass large reduction deformation is unfavorable for plate shape control, and the thickness of the strip steel is very thin and the deformation in the thickness direction is very uniform during the final pass rolling, so that the final pass reduction rate is controlled to be more than 14% in the embodiment, thereby ensuring that the strip steel can be deformed in the thickness and width directions, improving the uniformity of the hardness of the strip steel, refining the lamellar spacing of pearlite, providing good original tissues for heat treatment, and reducing the negative genetic influence of the coarse tissues on the heat treatment.
Furthermore, by adding a proper amount of hardenability element boron B into the steel strip component, the hardenability is improved to obtain a hard phase structure such as bainite or martensite, thereby ensuring the hardness and wear resistance of the steel strip after stamping and heat treatment.
In some embodiments, at the end of the heating treatment in step S1, the surface temperature of the cast slab is 1200±20 ℃, whereby high temperature heating is employed to ensure that C, B element in the steel strip composition is sufficiently solid-dissolved in austenite, increasing hardenability.
In some embodiments, in step S1, a step furnace is used to heat the casting blank, so that the heating is flexible, the heating quality is good, and the operation is convenient.
In some embodiments, in step S1, the cast slab is treated with high pressure water after tapping to remove surface scale. In some preferred embodiments, the high-pressure water treatment is carried out by adopting a high-pressure water dephosphorization box, the equipment is simple, the operation is easy, and the dephosphorization effect is good.
In this embodiment, the determination of the start rolling temperature is based on ensuring that the desired finish rolling temperature can be obtained, and if the finish rolling temperature is too high, coarse grain structure and lower strength are relatively easy to obtain, whereas if the finish rolling temperature is too low, strength is improved but shaping is reduced, so in this embodiment, during the rough rolling in step S2, the start rolling temperature is controlled to 1100±20 ℃ and the finish rolling temperature is controlled to be >1050 ℃, during the finish rolling, the start rolling temperature is controlled to be equal to or higher than 1050 ℃ and the finish rolling temperature is controlled to be 885-915 ℃, thereby facilitating rapid cooling after the finish rolling to obtain fine grain structure.
In some embodiments, in step S2, the cooling mode is laminar water cooling and air cooling alternately. Therefore, the curling temperature is controlled by the cooling mode, namely, the coiling temperature and the slow cooling of the steel belt are controlled, the phase-change structure is ensured to be ferrite and pearlite, and the temperature stress in the steel belt is fully released, so that the aim of reducing the hardness of the steel belt is fulfilled.
Therefore, the method for preparing a hot rolled steel strip for a garden tool according to this embodiment reduces internal stress of the steel to ensure cold stamping performance of the steel strip when the garden tool is prepared by cold stamping by controlling rolling temperature on one hand, and on the other hand, by controlling pass reduction rate and final pass reduction rate in rolling process to deform austenite component and generate sufficient structural defect and phase transition driving force, thereby refining ferrite and pearlite after rolling, providing good original structure for heat treatment, reducing negative influence of coarse structure on heat treatment, and improving hardenability to obtain hard phase structure such as bainite or martensite by adding appropriate amount of hardenability element B in the steel strip component, thereby ensuring hardness and wear resistance of the steel strip after stamping and heat treatment, so that tensile strength 646MPa (corresponding hardness is HRB 92) of the hot rolled steel strip for a garden tool according to the application is not less than 21%, the steel strip has good strong plasticity, and hardness after stamping and tempering treatment is not less than 52HRC, thereby meeting use requirements of the steel for garden.
The embodiment of the application also provides a hot rolled steel strip for a garden tool, which is prepared by adopting the preparation method of the hot rolled steel strip for the garden tool, and comprises the following components in percentage by mass: c:0.55% -0.60%, si is less than or equal to 0.10, mn:0.50% -0.70%, als 0.010% -0.020%, B:0.0012% -0.0020% of Fe and unavoidable impurities as the rest.
In the embodiment, the components and the contents thereof in the hot rolled steel strip for the garden tool can ensure that the surface of the shearing edge of the steel strip still can obtain a corresponding hard phase structure after the heat treatment, and are beneficial to improving the hardening layer after the heat treatment of the steel strip and improving the hardness, the wear resistance and the surface quality. In particular, the method comprises the steps of,
c: in the hot rolling process, a small amount of C content is removed from the surface of the strip steel due to high temperature, so that in the embodiment, the C content is controlled to be 0.55% -0.60% in order to ensure the hardness of the shearing edge after heat treatment;
als: the Als is designed to be more than 0.015%, and is mainly used for removing O element in molten steel as far as possible by adopting Al element, so that the influence of the O element on the decarburization of the surface of the steel strip in the high-temperature heat treatment process is reduced, and the Al element is also beneficial to refining grains and improving the toughness of the steel plate, so that the Als content is controlled to be 0.010-0.020%, and preferably, the Als content is controlled to be 0.015%;
mn: the performance of the steel can be effectively improved through solid solution strengthening and phase change strengthening, and in the embodiment, the Mn content is controlled to be 0.50-0.70%;
b: in order to improve the hardenability of the strip steel, the method is beneficial to improving the hardening layer after the heat treatment of the strip steel, improving the hardness and the wear resistance, and controlling 0.0012% -0.0020%;
si: in order to reduce the influence of the metal oxide on the surface of the strip steel, improve the surface quality of the garden tool after stamping and control Si to be less than or equal to 0.10.
In some embodiments, the nominal thickness of the hot rolled steel strip for a garden tool is 4mm or 4.1mm, and the actual thickness is 4.03-4.11mm, which is suitable for the processing of the garden tool.
In some embodiments, the hot rolled steel strip for a garden tool has a tensile strength of 630-646MPa, an elongation of 21-27%, and after heat treatment, the hot rolled steel strip for a garden tool has a hardness of 52-56HRC.
Therefore, the hot rolled steel strip for the garden tool has good cold stamping performance, and the steel strip has proper hardness and wear resistance after being subjected to quenching and tempering treatment, specifically, the tensile strength of the hot rolled steel strip for the garden tool is less than or equal to 646MPa (corresponding hardness is HRB 92), the elongation is more than or equal to 21%, the steel strip has good strong plasticity, the hot rolled steel strip is suitable for stamping treatment, and the hardness of the steel strip after being subjected to stamping and quenching and tempering treatment is more than or equal to 52HRC, so that the use requirement of the steel for the garden in the prior art is met.
The embodiment of the application also provides an application of the hot rolled steel strip for the garden tool, and the hot rolled steel strip for the garden tool is used for preparing the garden tool in a cold stamping mode.
In this embodiment, the hot rolled steel strip for a gardening tool is manufactured in a cold stamping manner, and specifically, in this embodiment, the hot rolled steel strip for a gardening tool is manufactured through stamping forming, tempering heat treatment, side grinding and sharpening processes. Therefore, when a garden tool is manufactured by adopting a cold stamping mode, good stamping performance is required in the steel strip stamping process, and the stamped garden tool needs to have good hardness after quenching and tempering heat treatment so that the shearing blade is sufficiently sharp after side grinding and sharpening, and the shearing blade also has good toughness in the use process to resist impact generated in the shearing process. Therefore, the hot rolled steel strip for the garden tool has good cold stamping performance, and the steel strip after being subjected to thermal refining has proper hardness and wear resistance, so that the use requirement of the steel for the garden can be met.
Example 1
The embodiment provides a hot rolled steel strip for garden tools, which comprises the following components in percentage by mass: c:0.55%, si:0.05%, mn:0.55%, als 0.035%, B:0.0018% and the balance of Fe and unavoidable impurities. In this example, the thickness of the hot rolled steel strip for a garden tool was 4.06mm.
The preparation method of the hot rolled steel strip for the garden tool in the embodiment comprises the following steps:
step S1: obtaining a casting blank after molten steel continuous casting and heating treatment by a step furnace, wherein the surface temperature of the casting blank is 1200 ℃ after the heating treatment is finished, and the surface temperature is the heating temperature in table 5;
step S2: and (3) carrying out rough rolling, finish rolling, cooling and coiling on the heat-treated casting blank in sequence to obtain a hot rolled steel strip for a garden tool, wherein the pass reduction rate and the pass reduction rate are shown in tables 3 and 4 in the rough rolling and/or the finish rolling process, the initial rolling temperature is controlled to be 1200+/-20 ℃ and the final rolling temperature is controlled to be more than 1050 ℃, the initial rolling temperature is controlled to be more than 1050 ℃ and the final rolling temperature is controlled to be 915 ℃ in the finish rolling process, the coiling temperature in the coiling process is 720 ℃, and the slow cooling time of the steel strip is 48 hours in the rough rolling process, and is shown in table 2.
Examples 2 to 6 are different from example 1 in the content of each main component and the hot rolling process parameters in the hot rolled steel strip for a gardening tool, and are shown in tables 1 to 4, wherein R1 and R2 in tables 3 and 4 represent rolling using two stands during rough rolling, F1 to F7 represent each finishing mill in a finishing mill group, and the mechanical properties of the hot rolled steel strip obtained in each example and the hardness test results after punching and tempering are shown in Table 5.
Table 1 actual thickness, chemical composition and mass% of the hot rolled steel strip (wt.%)
TABLE 2 temperature control of hot rolled strip in examples
TABLE 3 control of pass reduction during hot rolled strip rolling in examples
TABLE 4 control of pass reduction in hot rolled strip Rolling in examples
Table 5 mechanical properties of the Hot rolled Steel strips and hardness test results after Heat treatment in examples
Examples Thickness/mm Yield strength/MPa Tensile strength/MPa Elongation/% Hardness after heat treatment/HRC
1 4.06 341 637 24.5 54
2 4.05 336 638 25.5 55
3 4.05 358 643 26.5 56
4 4.11 362 645 21 54
5 4.03 363 646 23.5 53
6 4.06 336 630 27 52
As can be seen from the mechanical properties of the hot rolled steel strips in examples 1 to 6 in Table 5 and the hardness detection results after heat treatment, the hot rolled steel strips obtained in each example have good cold stamping properties, and the steel strips have proper hardness and wear resistance after quenching and tempering treatment, specifically, the tensile strength of the hot rolled steel strip for the garden tool is less than or equal to 646MPa (corresponding hardness is HRB 92), the elongation is more than or equal to 21%, the steel strip has good plasticity, the steel strip is suitable for stamping treatment, and the hardness of the steel strip after stamping and quenching and tempering treatment is more than or equal to 52HRC, so that the shearing edge is convenient to be sufficiently sharp after subsequent side grinding and sharpening treatment, and the shearing edge is ensured to have good toughness to resist the impact generated in the shearing process in the use process, and the use requirements of the garden steel in the prior art can be met.
Although the present disclosure is disclosed above, the scope of the present disclosure is not limited thereto. Various changes and modifications may be made by one skilled in the art without departing from the spirit and scope of the disclosure, and these changes and modifications will fall within the scope of the disclosure.

Claims (10)

1. A method for preparing a hot rolled steel strip for a garden tool, comprising:
step S1: obtaining a casting blank through continuous casting and heating treatment of molten steel;
step S2: and (3) sequentially performing rough rolling, finish rolling, cooling, coiling and slow cooling on the heated casting blank to obtain the hot rolled steel strip for the garden tool, wherein the pass reduction rate is more than or equal to 18% and the final pass reduction rate is more than 14% in the rough rolling and/or the finish rolling process, the coiling temperature in the coiling process is 680-720 ℃, and the slow cooling time in the slow cooling process of the steel strip is more than or equal to 48 hours, wherein the hot rolled steel strip for the garden tool comprises 0.0012% -0.0020% of boron by mass.
2. The method for producing a hot rolled steel strip for a garden tool as claimed in claim 1, wherein in step S1, the cast slab is heat treated by a step furnace, and at the end of the heat treatment, the surface temperature of the cast slab is 1200±20 ℃.
3. The method for producing a hot rolled steel strip for a garden tool as claimed in claim 1 wherein in step S1, the cast slab is treated with water under high pressure after tapping to remove surface scale.
4. The method of producing hot rolled steel strip for a garden tool as claimed in claim 1 wherein the initial rolling temperature is 1100±20 ℃ and the final rolling temperature is >1050 ℃ during the rough rolling in step S2.
5. The method for producing a hot rolled steel strip for a garden tool as claimed in claim 1, wherein the initial rolling temperature is equal to or higher than 1050 ℃ and the final rolling temperature is 885-915 ℃ during the finish rolling in step S2.
6. The method for producing a hot rolled steel strip for a garden tool as claimed in claim 1 wherein in step S2, the cooling means is a laminar water cooling and an air cooling alternately.
7. A hot rolled steel strip for a garden tool, characterized in that it is produced by the production method of a hot rolled steel strip for a garden tool as claimed in any one of claims 1 to 6, and comprises the following components in mass percent: c:0.55% -0.60%, si is less than or equal to 0.10%, mn:0.50% -0.70%, als 0.010% -0.020%, B:0.0012% -0.0020% of Fe and unavoidable impurities as the rest.
8. The hot rolled steel strip for a garden tool as claimed in claim 7, wherein the nominal thickness of the hot rolled steel strip for a garden tool is 4mm or 4.1mm, and the actual thickness is 4.03-4.11mm.
9. The hot rolled steel strip for a garden tool as claimed in claim 7, wherein the hot rolled steel strip for a garden tool has a tensile strength of 630-646MPa and an elongation of 21-27%.
10. Use of a hot rolled steel strip for a garden tool as claimed in any one of claims 7-9, wherein the hot rolled steel strip for a garden tool is cold stamped for manufacturing a garden tool, and wherein the hardness of the garden tool after heat treatment is 52-56HRC.
CN202310911417.2A 2023-07-24 2023-07-24 Hot rolled steel strip for garden tool, preparation method and application thereof Pending CN117123621A (en)

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CN202310911417.2A CN117123621A (en) 2023-07-24 2023-07-24 Hot rolled steel strip for garden tool, preparation method and application thereof

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202310911417.2A CN117123621A (en) 2023-07-24 2023-07-24 Hot rolled steel strip for garden tool, preparation method and application thereof

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CN117123621A true CN117123621A (en) 2023-11-28

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