CN114846170A - Steel plate for plate spring having excellent fatigue life and method for producing same - Google Patents
Steel plate for plate spring having excellent fatigue life and method for producing same Download PDFInfo
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- CN114846170A CN114846170A CN202080088945.7A CN202080088945A CN114846170A CN 114846170 A CN114846170 A CN 114846170A CN 202080088945 A CN202080088945 A CN 202080088945A CN 114846170 A CN114846170 A CN 114846170A
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- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 84
- 239000010959 steel Substances 0.000 title claims abstract description 84
- 238000004519 manufacturing process Methods 0.000 title claims description 15
- LEONUFNNVUYDNQ-UHFFFAOYSA-N vanadium atom Chemical compound [V] LEONUFNNVUYDNQ-UHFFFAOYSA-N 0.000 claims abstract description 49
- INZDTEICWPZYJM-UHFFFAOYSA-N 1-(chloromethyl)-4-[4-(chloromethyl)phenyl]benzene Chemical compound C1=CC(CCl)=CC=C1C1=CC=C(CCl)C=C1 INZDTEICWPZYJM-UHFFFAOYSA-N 0.000 claims abstract description 35
- 239000011651 chromium Substances 0.000 claims abstract description 34
- 239000011572 manganese Substances 0.000 claims abstract description 34
- 229910001562 pearlite Inorganic materials 0.000 claims abstract description 29
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 21
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 21
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 claims abstract description 17
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 claims abstract description 17
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims abstract description 17
- 229910052804 chromium Inorganic materials 0.000 claims abstract description 17
- 229910052748 manganese Inorganic materials 0.000 claims abstract description 17
- 229910052710 silicon Inorganic materials 0.000 claims abstract description 17
- 239000010703 silicon Substances 0.000 claims abstract description 17
- 229910001566 austenite Inorganic materials 0.000 claims abstract description 16
- 239000012535 impurity Substances 0.000 claims abstract description 13
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 claims abstract description 11
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 claims abstract description 11
- 229910052698 phosphorus Inorganic materials 0.000 claims abstract description 11
- 239000011574 phosphorus Substances 0.000 claims abstract description 11
- 229910052717 sulfur Inorganic materials 0.000 claims abstract description 11
- 239000011593 sulfur Substances 0.000 claims abstract description 11
- 239000000463 material Substances 0.000 claims description 94
- 238000001816 cooling Methods 0.000 claims description 24
- 238000003303 reheating Methods 0.000 claims description 23
- 238000005096 rolling process Methods 0.000 claims description 18
- 230000009467 reduction Effects 0.000 claims description 15
- 238000000034 method Methods 0.000 claims description 12
- 230000001186 cumulative effect Effects 0.000 claims description 8
- 150000003839 salts Chemical class 0.000 claims description 6
- 239000011229 interlayer Substances 0.000 claims description 5
- 238000005097 cold rolling Methods 0.000 claims description 4
- 238000010583 slow cooling Methods 0.000 claims description 4
- 238000012423 maintenance Methods 0.000 claims description 3
- ZLANVVMKMCTKMT-UHFFFAOYSA-N methanidylidynevanadium(1+) Chemical class [V+]#[C-] ZLANVVMKMCTKMT-UHFFFAOYSA-N 0.000 claims 1
- 239000000203 mixture Substances 0.000 description 12
- 229910045601 alloy Inorganic materials 0.000 description 10
- 239000000956 alloy Substances 0.000 description 10
- 230000000694 effects Effects 0.000 description 10
- 239000006104 solid solution Substances 0.000 description 8
- 230000015572 biosynthetic process Effects 0.000 description 6
- 238000005728 strengthening Methods 0.000 description 5
- 150000001247 metal acetylides Chemical class 0.000 description 4
- 230000000704 physical effect Effects 0.000 description 4
- 238000005098 hot rolling Methods 0.000 description 3
- 230000003287 optical effect Effects 0.000 description 3
- 238000004881 precipitation hardening Methods 0.000 description 3
- 230000008569 process Effects 0.000 description 3
- 229910001563 bainite Inorganic materials 0.000 description 2
- 230000003749 cleanliness Effects 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 238000005482 strain hardening Methods 0.000 description 2
- 229910000859 α-Fe Inorganic materials 0.000 description 2
- SNIOPGDIGTZGOP-UHFFFAOYSA-N Nitroglycerin Chemical compound [O-][N+](=O)OCC(O[N+]([O-])=O)CO[N+]([O-])=O SNIOPGDIGTZGOP-UHFFFAOYSA-N 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 229910001567 cementite Inorganic materials 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000006477 desulfuration reaction Methods 0.000 description 1
- 230000023556 desulfurization Effects 0.000 description 1
- 238000005530 etching Methods 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 239000004615 ingredient Substances 0.000 description 1
- KSOKAHYVTMZFBJ-UHFFFAOYSA-N iron;methane Chemical compound C.[Fe].[Fe].[Fe] KSOKAHYVTMZFBJ-UHFFFAOYSA-N 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 229940073020 nitrol Drugs 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 230000009257 reactivity Effects 0.000 description 1
- 238000007670 refining Methods 0.000 description 1
- 230000000979 retarding effect Effects 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 238000005204 segregation Methods 0.000 description 1
- 230000006641 stabilisation Effects 0.000 description 1
- 238000011105 stabilization Methods 0.000 description 1
- 238000009628 steelmaking Methods 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
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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
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/46—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for sheet metals
-
- 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
-
- 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
-
- 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
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/18—Hardening; Quenching with or without subsequent tempering
- C21D1/19—Hardening; Quenching with or without subsequent tempering by interrupted quenching
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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
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/26—Methods of annealing
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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
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/26—Methods of annealing
- C21D1/32—Soft annealing, e.g. spheroidising
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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
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/34—Methods of heating
- C21D1/44—Methods of heating in heat-treatment baths
- C21D1/46—Salt baths
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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
- 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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- 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
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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
- 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
- C21D8/0236—Cold rolling
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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
- 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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- 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
- C21D8/12—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties
- C21D8/1216—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties the working step(s) being of interest
- C21D8/1222—Hot rolling
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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
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/12—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties
- C21D8/1216—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties the working step(s) being of interest
- C21D8/1233—Cold rolling
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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
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/02—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for springs
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- 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
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- 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
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- 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
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
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- 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
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/24—Ferrous alloys, e.g. steel alloys containing chromium with vanadium
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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
- C21D2211/001—Austenite
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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
Abstract
The steel plate for a plate spring according to an aspect of the present invention may include, in wt%: carbon (C): 0.7-1.0%, silicon (Si): 0.1-0.4%, manganese (Mn): 0.2-1.0%, chromium (Cr): 0.05-2.0%, vanadium (V): 0.07-0.2%, phosphorus (P): 0.03% or less, sulfur (S): 0.03% or less, and the balance Fe and unavoidable impurities, the fine structure may contain 99% by area or more of pearlite and 1% by area or less (excluding 0%) of Vanadium Carbide (VC), and the prior austenite may have an average grain size of 28 μm or less.
Description
Technical Field
The present invention relates to a steel sheet for a member material used in an environment where a constant load is repeated at constant intervals, and a method for manufacturing the same.
Background
In the case of a member used in an environment where a load is repeatedly applied at certain intervals, it is necessary to have an excellent fatigue life in terms of ensuring durability of the member. The safety belt of a vehicle has a structure in which a belt is coupled with a plate spring, so that it is easy for a user to detach, and the fatigue life of the plate spring is an important factor affecting the durability of the safety belt. In particular, the seat belt is a component directly related to the safety of a passenger, and thus the plate spring provided to the seat belt should have excellent durability so as not to reach the fatigue limit during the life cycle of the vehicle, but the development of such a material has not been made at present.
Patent document 1 proposes a steel plate for a spring having improved strength by using upper bainite, but the introduction of upper bainite causes variations in the physical properties of the steel plate, which results in a problem that the durability of the spring is rather reduced.
(Prior art document)
(patent document 1) Korean laid-open patent publication No. 10-2008-0060619 (published 2008/07/02/10)
Disclosure of Invention
Technical problem to be solved
According to one aspect of the present invention, a steel material having excellent workability and a method for producing the same can be provided.
The technical problem of the present invention is not limited to the above. Additional technical problems of the present invention can be easily understood by those skilled in the art based on the entire contents of the present specification.
Technical scheme
The steel plate for a plate spring according to an aspect of the present invention may include, in wt%: carbon (C): 0.7-1.0%, silicon (Si): 0.1-0.4%, manganese (Mn): 0.2-1.0%, chromium (Cr): 0.05-2.0%, vanadium (V): 0.07-0.2%, phosphorus (P): 0.03% or less, sulfur (S): 0.03% or less, and the balance Fe and inevitable impurities, the fine structure may include 99 area% or more of pearlite and 1 area% or less (excluding 0%) of Vanadium Carbide (VC), and the prior austenite may have an average grain size of 28 μm or less.
The vanadium (V) content (Vs) of the steel sheet and the vanadium (V) content (Vp) of the pearlite may satisfy the following relational expression 1.
[ relational expression 1]
Vs>Vp
In the relation 1, Vs denotes a vanadium (V) content (wt%) of the steel sheet, and Vp denotes a vanadium (V) content (wt%) of pearlite.
The Vanadium Carbide (VC) may be present in a fraction of 0.002 area% or more.
The pearlite may have an average interlayer spacing of 0.09 to 0.12 μm.
The prior austenite may have an average particle size of 2 μm or more.
The steel sheet may have a surface hardness of 410(HB) or more on the brinell hardness basis.
The thickness of the steel plate may be 3mm or less (except for 0 mm).
The method of manufacturing a steel plate for a plate spring according to one aspect of the present invention may include the steps of: providing a hot rolled material comprising, in weight percent, carbon (C): 0.7-1.0%, silicon (Si): 0.1-0.4%, manganese (Mn): 0.2-1.0%, chromium (Cr): 0.05-2.0%, vanadium (V): 0.07-0.2%, phosphorus (P): 0.03% or less, sulfur (S): less than 0.03%, and the balance of Fe and inevitable impurities; reheating the hot rolled material, and then putting the reheated material into a salt bath at 400-600 ℃ to perform isothermal maintenance; and cold-rolling the hot-rolled material held isothermally at a cumulative reduction of 50% or more to provide a cold-rolled material, wherein, with respect to the reheating of the hot-rolled material, the hot-rolled material is reheated in a temperature range of 900 ℃ or more and less than 1000 ℃ when the vanadium (V) content of the hot-rolled material is less than 0.15%, and the hot-rolled material is reheated in a temperature range of 900-.
The step of providing the hot rolled material may comprise the steps of: reheating the slab to a temperature range of 1000-1300 ℃; a rough rolling step of rough rolling the reheated slab at an accumulated reduction of 60% or more to provide an intermediate material; a finish rolling step of rolling the intermediate material at an accumulated reduction of 60% or more and rolling the intermediate material at an outlet temperature of 700-; a first cooling step, using slow cooling condition to cool to a first cooling termination temperature of 500-; a first holding step of isothermally holding the hot-rolled material at the first cooling termination temperature; and a second cooling step of cooling the isothermally held hot-rolled material to normal temperature by furnace cooling.
Advantageous effects
According to a preferred aspect of the present invention, it is possible to provide a steel plate for a plate spring, which has an effectively improved fatigue life and thus excellent durability.
Drawings
Fig. 1 to 3 are photographs of prior austenite grains of test piece 4, test piece 5 and test piece 6, respectively, observed by an optical microscope.
Fig. 4 to 6 are photographs of pearlite structures of test pieces 4, 5, and 6 observed with a Scanning Electron Microscope (SEM).
Best mode for carrying out the invention
The present invention relates to a steel plate for a plate spring excellent in fatigue life and a method for manufacturing the same, and preferred embodiments of the present invention will be described below. The embodiments of the present invention may be modified into various forms and should not be construed as limiting the scope of the present invention to the embodiments described below. This specific embodiment is provided to explain the present invention in more detail to those skilled in the art.
The inventors of the present invention have conducted intensive studies on a method for improving the fatigue life of a steel material part used in an environment where a certain load is repeatedly applied at certain intervals, and have recognized that the fatigue life of a steel material can be effectively improved by suppressing the formation and propagation of fatigue cracks when the physical properties of the steel material itself are reinforced, thereby completing the present invention.
As a method for increasing the strength and hardness of a steel material, mechanisms such as solid solution strengthening, work hardening, grain refinement, and precipitation hardening are typically known. The inventors of the present invention have studied a method for improving the strength and hardness of a steel material by adding a large amount of carbon (C) as a solid solution strengthening element, but when the amount of carbon (C) added exceeds a certain level, it is confirmed that a large amount of hard, coarse carbides are formed along grain boundaries, and the formation and propagation of fatigue cracks are promoted instead. That is, it is found that the effect of improving the fatigue life to a desired level cannot be expected only by the solid solution strengthening. Further, the inventors of the present invention have studied a method of improving the strength and hardness of a steel material by work hardening, but as the amount of work increases, the strength and hardness of the steel material increase, creating an environment advantageous for suppressing the formation and propagation of fatigue cracks, but when the amount of work exceeds a certain level, it is confirmed that the formation of defects is induced inside the steel material, resulting in the decrease of fatigue life on the contrary.
Accordingly, the inventors of the present invention have conducted intensive studies on a method of effectively ensuring the strength and hardness of a steel material through precipitation hardening and grain refinement while ensuring the effect of solid solution strengthening by including carbon (C) at a certain level or more, and have confirmed that the hardness and strength of a steel material can be effectively improved by maximizing the precipitation hardening and grain refinement effects in the case of adding carbon (C) at an appropriate level to the steel material but using Vanadium Carbide (VC), thereby completing the present invention.
Hereinafter, a steel material for a plate spring according to an aspect of the present invention will be described in more detail.
The steel material for a plate spring according to an aspect of the present invention may include, in wt%: carbon (C): 0.7-1.0%, silicon (Si): 0.1-0.4%, manganese (Mn): 0.2-1.0%, chromium (Cr): 0.05-2.0%, vanadium (V): 0.07-0.2%, phosphorus (P): 0.03% or less, sulfur (S): 0.03% or less, and the balance Fe and inevitable impurities, the fine structure may include 99 area% or more of pearlite and 1 area% or less (excluding 0%) of Vanadium Carbide (VC), and the prior austenite may have an average grain size of 28 μm or less.
The alloy composition of the present invention will be described in more detail below. Hereinafter,% and ppm relating to the content of the alloy composition are on a weight basis unless otherwise specified.
The steel material for a plate spring according to an aspect of the present invention may include, in wt%: carbon (C): 0.7-1.0%, silicon (Si): 0.1-0.4%, manganese (Mn): 0.2-1.0%, chromium (Cr): 0.05-2.0%, vanadium (V): 0.07-0.2%, phosphorus (P): 0.03% or less, sulfur (S): less than 0.03%, and the balance Fe and inevitable impurities.
Carbon (C): 0.7 to 1.0 percent
Carbon (C) is not only a representative element that improves hardenability, but also an element that effectively contributes to improving strength and hardness of steel by solid-solution strengthening. Therefore, for the above-described effects, carbon (C) may be contained in an amount of 0.7% or more in the present invention. The carbon (C) content may be preferably 0.75% or more, and more preferably 0.8% or more. On the other hand, carbon (C) has a low solid solution limit in ferrite, and reacts with carbide-forming elements to form precipitates or combines with Fe to form cementite (Fe) 3 C) Therefore, if the amount of carbon (C) added is too large, a large amount of hard carbide is formed, which may adversely affect the fatigue life. Therefore, in the present invention, the upper limit of the carbon (C) content may be limited to 1.0%. The carbon (C) content may be preferably 0.95% or less, and more preferably 0.9% or less.
Silicon (Si): 0.1 to 0.4 percent
Silicon (Si) is not only an element that stabilizes ferrite but also an element that effectively contributes to an increase in the strength and hardness of a steel material by retarding the transformation rate of pearlite to refine the interlayer spacing of pearlite. Therefore, in the present invention, silicon (Si) may be contained by 0.1% or more for the effect described above. The preferable content of silicon (Si) may be 0.15% or more, and the more preferable content of silicon (Si) may be 0.2% or more. However, when too much silicon (Si) is added, not only the hot workability and toughness are reduced, but also the surface quality may be reduced, so the upper limit of the silicon (Si) content may be limited to 0.4% in the present invention. The preferable content of silicon (Si) may be 0.35% or less, and the more preferable content of silicon (Si) may be 0.3% or less.
Manganese (Mn): 0.2 to 1.0 percent
Manganese (Mn) is not only an element that contributes to improving the hardenability of steel, but also an element that effectively contributes to ensuring the cleanliness of steel through deoxidation and desulfurization. Therefore, the present invention may contain 0.2% or more of manganese (Mn). The preferred manganese (Mn) content may be 0.3% or more, and the more preferred manganese (Mn) content may be 0.4% or more. However, since the addition of too much manganese (Mn) forms a segregation phase in the center of the steel sheet to lower workability, the upper limit of the manganese (Mn) content may be limited to 1.0% in the present invention. The preferred manganese (Mn) content may be 0.8% or less, and the more preferred manganese (Mn) content may be 0.6% or less.
Chromium (Cr): 0.05 to 2.0 percent
Chromium (Cr) is an element contributing to improvement of hardenability of steel. Chromium (Cr) is also an element that not only forms fine carbides, but also contributes to effectively improving the strength and hardness of steel by refining the interlamellar spacing of pearlite. Therefore, 0.05% or more of chromium (Cr) may be contained in the present invention. The preferable chromium (Cr) content may be 0.07% or more. However, when chromium (Cr) is excessively added, toughness may be reduced due to excessive hardenability or heat treatability may be reduced due to stabilization of carbides, so the upper limit of the content of chromium (Cr) may be limited to 2.0% in the present invention. The preferable chromium (Cr) content may be 1.5% or less, and the more preferable chromium (Cr) content may be 1.0% or less.
Vanadium (V): 0.07-0.2%
In the present invention, vanadium (V) is an element that must be added in order to improve the strength and hardness of the steel. This is because vanadium (V) is not only an element which is easily heat-treated and has low reactivity with oxygen, but also an element which reacts with carbon (C) in steel to precipitate fine Vanadium Carbide (VC) and effectively contributes to refinement of austenite crystal grains. Therefore, 0.07% or more of vanadium (V) may be contained in the present invention. More preferably, the vanadium (V) content may be 0.1% or more. However, when the content of vanadium (V) exceeds a certain level, the effect of adding vanadium (V) is saturated, but vanadium (V) as a high-valence element is not preferable in terms of economy, so the upper limit of the content of vanadium (V) may be limited to 0.2% in the present invention. More preferably, the vanadium (V) content may be 0.18% or less.
Phosphorus (P): 0.03% or less (including 0%), sulfur (S): less than 0.03% (including 0%)
Phosphorus (P) and sulfur (S) are representative impurity elements, and in the present invention, it is attempted to minimize the contents of these components in terms of ensuring the cleanliness of the steel. However, in view of the economy in the conventional steel making process, the upper limits of the contents of phosphorus (P) and sulfur (S) may be limited to 0.03%, respectively, in the present invention.
The steel plate for a plate spring according to one aspect of the present invention may contain Fe and other inevitable impurities for the remainder in addition to the above components. However, undesirable impurities may be inevitably mixed from raw materials or the surrounding environment in a general manufacturing process, and thus, the impurities cannot be completely excluded. These impurities are well known to those skilled in the art and therefore not all of them are specifically mentioned in this specification. Further, the addition of effective ingredients other than the above-mentioned composition is not completely excluded.
In the steel plate for a plate spring according to one aspect of the present invention, the microstructure may include 99 area% or more of pearlite and 1 area% or less (excluding 0%) of Vanadium Carbide (VC). The lower limit of the fraction of Vanadium Carbide (VC) may be preferably 0.002 area% or more. That is, the steel plate for a plate spring according to one aspect of the present invention may have a fine structure including a certain level of Vanadium Carbide (VC) in a pearlite single phase structure.
Further, in the steel plate for a plate spring according to one aspect of the present invention, the content (Vs, wt%) of vanadium (V) contained in the steel plate and the content (Vp, wt%) of vanadium (V) contained in pearlite may satisfy the following relational expression 1.
[ relational expression 1]
Vs>Vp
In the relational expression 1, Vs means the content (wt%) of vanadium (V) contained in the steel sheet, and Vp means the content (wt%) of vanadium (V) contained in pearlite. The general technicians can confirm Vp and Vs by analytical methods generally performed in the present technical field without particular technical difficulties.
That is, in the steel plate for a plate spring according to one aspect of the present invention, since vanadium (V) is not completely dissolved in a pearlite structure, it may mean that a part of vanadium (V) is precipitated as Vanadium Carbide (VC). Therefore, in the steel plate for a plate spring according to one aspect of the present invention, the effect of improving the strength and hardness of the steel plate by precipitation of Vanadium Carbide (VC) can be expected.
In the steel plate for a plate spring according to one aspect of the present invention, the average grain size of prior austenite (average grain size at austenitizing temperature) may be 28 μm or less, and the preferred average grain size of prior austenite may be 2 μm or more. Further, the average interlamellar spacing of the preferred pearlite may be 0.09 to 0.12 μm. That is, it is known that the steel sheet for a plate spring according to one aspect of the present invention is manufactured by heat-treating a hot-rolled material to which vanadium (V) is added, and therefore, the structure is refined by Vanadium Carbide (VC) existing in the state of the hot-rolled material. Therefore, in the steel plate for a plate spring according to one aspect of the present invention, the effect of improving the strength and hardness of the steel plate due to the miniaturization of the structure can be expected.
The thickness of the steel plate for a plate spring according to one aspect of the present invention is not particularly limited, but may preferably have a thickness of 3mm or less (excluding 0 mm).
The steel plate for a plate spring according to one aspect of the present invention may have a surface hardness of 410(HB) or more based on the brinell hardness, and in the case of a plate spring manufactured using the steel plate of the present invention, the expected fatigue life calculated by the following relational expression 2 may be 15 × 10 4 The above steps are repeated.
[ relational expression 2]
0.35＝{(4.25*HB+225)*(2Nf) -0.09 }/E+(0.32*HB 2 -487*HB+19.1*10 3 )*{(2Nf) -0.56 }/E
In the relational expression 2, HB denotes the brinell hardness of the steel sheet surface, and 2Nf denotes the fatigue life. Further, E of the relational expression 2 means an elastic coefficient, and a fixed value of 210GPa is utilized in the present invention.
Therefore, according to an aspect of the present invention, it is possible to provide a steel plate for a plate spring, which has an excellent fatigue life also in an environment in which a certain load is continuously repeated at certain intervals.
Hereinafter, a method for manufacturing a steel plate for a spring according to one aspect of the present invention will be described in more detail.
The method of manufacturing a steel plate for a spring according to one aspect of the present invention may include the steps of: providing a hot rolled material comprising, in weight percent, carbon (C): 0.7-1.0%, silicon (Si): 0.1-0.4%, manganese (Mn): 0.2-1.0%, chromium (Cr): 0.05-2.0%, vanadium (V): 0.07-0.2%, phosphorus (P): 0.03% or less, sulfur (S): less than 0.03%, and the balance of Fe and inevitable impurities; reheating the hot rolled material, and then putting the reheated material into a salt bath at 400-600 ℃ to perform isothermal maintenance; and cold rolling the hot rolled material maintained isothermally at a cumulative reduction of 50% or more to provide a cold rolled material, wherein, with respect to the reheating of the hot rolled material, when the vanadium (V) content of the hot rolled material is less than 0.15%, the hot rolled material is reheated in a temperature range of 900 ℃ or more and less than 1000 ℃, and when the vanadium (V) content of the hot rolled material is 0.15% or more, the hot rolled material is reheated in a temperature range of 900-.
The step of providing the hot rolled material may comprise the steps of: reheating the slab to a temperature range of 1000-1300 ℃; a rough rolling step of rough rolling the reheated slab at an accumulated reduction of 60% or more to provide an intermediate material; a finish rolling step of rolling the intermediate material at an accumulated reduction of 60% or more and rolling the intermediate material at an outlet temperature of 700-; a first cooling step, using slow cooling condition to cool to a first cooling termination temperature of 500-; a first holding step of isothermally holding the hot-rolled material at the first cooling termination temperature; and a second cooling step of cooling the isothermally held hot-rolled material to normal temperature by furnace cooling.
Providing a hot rolled material
After a slab having a predetermined alloy composition is prepared, reheating and hot rolling of the slab can be performed. Since the slab of the present invention has an alloy composition corresponding to the alloy composition of the steel sheet, the description of the alloy composition of the steel sheet is used in the present invention instead of the description of the alloy composition of the slab.
The reheating temperature of the slab of the present invention is not particularly limited, but the reheating of the slab may be performed at 1000-. The reheated slab may be rough-rolled at a cumulative reduction ratio of 60% or more to provide an intermediate material, and then finish-rolled at a cumulative reduction ratio of 60% or more to provide a hot-rolled material. In order to suppress the formation of coarse structures, the upper limit of the outlet temperature of the finish rolling may be limited to 1000 ℃, and the lower limit of the outlet temperature may be limited to 700 ℃ in consideration of the rolling load. The upper limit of the preferred outlet temperature may be 920 c and the lower limit of the preferred outlet temperature may be 830 c.
The hot rolled material after completion of hot rolling may be cooled in two stages after being wound. That is, the primary cooling may be performed using slow cooling conditions to a first cooling end temperature of 500-. The cooling rate of the first cooling may be 20-100 c/sec. The isothermal holding may be performed in a state of hot-rolling a coil, and the isothermal holding time may be 30 to 90 minutes. The cooling rate of the secondary cooling may be 5 ℃/sec or less.
Reheating and isothermal holding of hot rolled material
In order to control the microstructure, a process may be performed in which the hot-rolled material is reheated to a certain temperature range and then placed in a salt bath set to a pearlite temperature to be isothermally held. The reheating temperature of the hot rolled material may be selectively utilized according to the content of vanadium (V) contained in the hot rolled material. Here, the content of vanadium (V) contained in the hot-rolled material may be interpreted as meaning corresponding to the content of vanadium (V) contained in the slab.
When the vanadium (V) content of the hot rolled material is less than 0.15%, reheating of the hot rolled material may be performed in a temperature range of 900 ℃ or more and less than 1000 ℃. Further, when the vanadium (V) content of the hot rolled material is 0.15% or more, reheating of the hot rolled material may be performed in a temperature range of 900-. That is, in order to leave a certain level of Vanadium Carbide (VC) in the final steel sheet, a reheating temperature range according to the content of vanadium (V) may be selectively utilized in the present invention.
In the present invention, the reheating time of the hot rolled material is not particularly limited, but the reheating time of the hot rolled material in which the effects of preventing coarsening of the microstructure and preventing complete solid solution of carbides are comprehensively considered may be 1 minute to 10 minutes. The lower limit of the reheating time of the preferred hot rolled material may be 3 minutes, and the upper limit of the reheating time of the preferred hot rolled material may be 5 minutes.
The reheated hot rolled material is charged into a 400-through 600 ℃ salt bath and then isothermally held, whereby the fine structure of the final steel sheet can be provided as a pearlite single-phase structure. In the present invention, the isothermal holding time is not particularly limited, but isothermal holding may be performed for 30 seconds or more in order to prevent the local formation of a low-temperature structure and reduce the fatigue life. Furthermore, the preferred isothermal holding time, considering together the achievement and economy of the desired final texture, may be in the range of 60-150 seconds.
The hot rolled material kept at the constant temperature is cold rolled under the condition that the cumulative reduction rate is 50% or more, thereby providing a steel sheet having a final thickness of 3mm or less.
The steel plate for a plate spring manufactured by the above manufacturing method may include 99 area% or more of pearlite and 1 area% or less (excluding 0%) of Vanadium Carbide (VC) in the microstructure, and the vanadium (V) content (Vs, wt%) and the vanadium (V) content (Vp, wt%) of pearlite of the steel plate may satisfy the following relational expression 1.
[ relational expression 1]
Vs>Vp
In the relation 1, Vs means a content (wt%) of vanadium (V) contained in the steel sheet, and Vp means a content (wt%) of vanadium (V) contained in Vanadium Carbide (VC).
In addition, in the steel plate for a plate spring manufactured by the above manufacturing method, the average grain size of prior austenite (average grain size at austenitizing temperature) may be 28 μm or less, and the average interlamellar spacing of pearlite may be in the range of 0.09 to 0.12 μm.
The steel plate for a plate spring manufactured by the above manufacturing method may have a hardness of 410(HB) or more based on the brinell hardness, and the expected fatigue life calculated by the following relational expression 2 may satisfy 15 × 10 in the case of a plate spring manufactured using the steel plate 4 The above steps are repeated.
[ relational expression 2]
0.35＝{(4.25*HB+225)*(2Nf) -0.09 }/E+(0.32*HB 2 -487*HB+19.1*10 3 )*{(2Nf) -0.56 }/E
In the relational expression 2, HB denotes the brinell hardness of the steel sheet surface, and 2Nf denotes the fatigue life. Further, E of the relational expression 2 means an elastic coefficient, and a fixed value of 210GPa is utilized in the present invention.
Detailed Description
The present invention will be described more specifically with reference to examples. However, it should be noted that the following examples are only for illustrating and embodying the present invention, and are not intended to limit the scope of the claims of the present invention.
(examples)
A slab having an alloy composition of table 1 was reheated in a temperature range of 1200 ℃, and then rough rolled at a cumulative reduction of 60% and finish rolled at a cumulative reduction of 80%, thereby manufacturing a hot rolled material test piece. In this case, the exit temperature of finish rolling was 850 ℃. Under the conditions of table 2, each of the hot rolled material test pieces was reheated, and then charged into a salt bath at 600 ℃ or lower for isothermal holding, and a final cold rolled material test piece was manufactured with a cold rolling reduction of 80%. The microstructure and carbide of each cold rolled material test piece were observed, and the results are shown in table 2. Further, the surface hardness of the hot rolled material test piece and the final cold rolled material test piece before and after the isothermal heat treatment were measured, respectively, and the results thereof are shown in table 3.
In the observation of the fine structure, the surface of the polished test piece was subjected to 2% nitrol etching, and then the grain size of prior austenite was observed at a magnification of 200 times with an optical microscope, and the structure composition and the interlamellar spacing of pearlite were observed at a magnification of 500 times with a Scanning Electron Microscope (SEM). The hardness of each sample was measured using a vickers hardness tester, and the hardness values at 10 points of each test piece were measured using a load of 10kg to calculate an average value.
[ Table 1]
[ Table 2]
The average size of AGS refers to the average grain size of the prior austenite.
[ Table 3]
As shown in tables 1 to 3, the fine structure and physical properties desired by the present invention were confirmed to be satisfied in the case of the test pieces 5 to 9 satisfying the alloy composition and process conditions of the present invention, while the fine structure and physical properties desired by the present invention were confirmed to be not satisfied in the case of the test pieces 1 to 4 not satisfying any one or more of the alloy composition and process conditions of the present invention.
In particular, in the case of test piece 5, although the vanadium (V) content satisfying the limitation of the present invention was satisfied, since the reheating temperature of the hot rolled material exceeded the limitation of the present invention, it was confirmed that re-solid solution of Vanadium Carbide (VC) occurred in the test piece of the hot rolled material.
Fig. 1 to 3 are photographs of the prior austenite grains of the test piece 4, the test piece 5 and the test piece 6, respectively, which were observed by an optical microscope, and it was confirmed that the average size of the prior austenite grains of the test piece 4 was the largest and the average size of the prior austenite grains of the test piece 6 was the smallest.
Fig. 4 to 6 are photographs of the pearlite structures of the test pieces 4, 5, and 6 observed with a Scanning Electron Microscope (SEM), and it was confirmed that the pearlite average interlayer spacing of the test pieces 5 and 6 was smaller than the pearlite average interlayer spacing of the test piece 4.
The present invention has been described in detail with reference to the embodiments, but other embodiments may be included. Therefore, the technical spirit and scope of the claims are not limited to the embodiments.
Claims (9)
1. A steel plate for a plate spring, comprising in weight%: carbon (C): 0.7-1.0%, silicon (Si): 0.1-0.4%, manganese (Mn): 0.2-1.0%, chromium (Cr): 0.05-2.0%, vanadium (V): 0.07-0.2%, phosphorus (P): 0.03% or less, sulfur (S): less than 0.03%, and the balance of Fe and inevitable impurities,
the fine structure comprises 99 area% or more of pearlite and 1 area% or less of Vanadium Carbide (VC) except 0%,
the prior austenite has an average grain size of 28 μm or less.
2. The steel plate for a plate spring according to claim 1, wherein a vanadium (V) content (Vs) of the steel plate and a vanadium (V) content (Vp) of the pearlite satisfy the following relational expression 1,
[ relational expression 1]
Vs>Vp
In the relation 1, Vs denotes a vanadium (V) content (wt%) of the steel sheet, and Vp denotes a vanadium (V) content (wt%) of pearlite.
3. Steel plate for sheet springs according to claim 1, wherein the fraction of Vanadium Carbides (VC) is 0.002 area% or more.
4. Steel plate for sheet springs according to claim 1, wherein the pearlite has an average interlayer spacing of 0.09-0.12 μm.
5. The steel plate for a plate spring according to claim 1, wherein the prior austenite has an average grain size of 2 μm or more.
6. The steel plate for a plate spring according to claim 1, wherein the steel plate has a surface hardness of 410(HB) or more on the Brinell hardness basis.
7. The steel plate for a plate spring according to claim 1, wherein the thickness of the steel plate is 3mm or less except 0 mm.
8. A method of manufacturing a steel plate for a plate spring, comprising the steps of:
providing a hot rolled material comprising, in weight percent, carbon (C): 0.7-1.0%, silicon (Si): 0.1-0.4%, manganese (Mn): 0.2-1.0%, chromium (Cr): 0.05-2.0%, vanadium (V): 0.07-0.2%, phosphorus (P): 0.03% or less, sulfur (S): less than 0.03%, and the balance of Fe and inevitable impurities;
reheating the hot rolled material, and then putting the reheated material into a salt bath at 400-600 ℃ to perform isothermal maintenance; and
cold rolling the isothermally held hot-rolled material at a cumulative reduction of 50% or more to provide a cold-rolled material,
wherein, in the reheating of the hot-rolled material, when the vanadium (V) content of the hot-rolled material is less than 0.15%, the hot-rolled material is reheated at a temperature range of 900 ℃ or more and less than 1000 ℃,
reheating the hot rolled material at a temperature range of 900-1050 ℃ when the vanadium (V) content of the hot rolled material is 0.15% or more.
9. The method for manufacturing a steel plate for a plate spring according to claim 8, wherein the step of providing the hot rolled material comprises the steps of:
reheating the slab to a temperature range of 1000-1300 ℃;
a rough rolling step of rough rolling the reheated slab at an accumulated reduction of 60% or more to provide an intermediate material;
a finish rolling step of rolling the intermediate material at an accumulated reduction of 60% or more and rolling the intermediate material at an outlet temperature of 700-;
a first cooling step, using slow cooling condition to cool to a first cooling termination temperature of 500-;
a first holding step of isothermally holding the hot-rolled material at the first cooling termination temperature; and
a second cooling step of cooling the isothermally held hot rolled material to normal temperature by furnace cooling.
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| KR10-2019-0171858 | 2019-12-20 | ||
| KR1020190171858A KR102327929B1 (en) | 2019-12-20 | 2019-12-20 | Steel sheet having fatigue life for leaf spring and manufacturing method for the same |
| PCT/KR2020/017990 WO2021125688A1 (en) | 2019-12-20 | 2020-12-10 | Leaf spring steel sheet having excellent fatigue life, and manufacturing method therefor |
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| EP (1) | EP4079908A1 (en) |
| KR (1) | KR102327929B1 (en) |
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH08302428A (en) * | 1995-05-10 | 1996-11-19 | Nisshin Steel Co Ltd | Production of high strength steel strip for spring |
| JP2007100126A (en) * | 2005-09-30 | 2007-04-19 | Ntn Corp | Rolling member and ball bearing |
| KR20100021273A (en) * | 2008-08-14 | 2010-02-24 | 주식회사 포스코 | High carbon hot rolled steel coil and manufacturing method thereof |
| KR101445868B1 (en) * | 2007-06-05 | 2014-10-01 | 주식회사 포스코 | High carbon steel sheet superior in fatiugue lifeand manufacturing method thereof |
| KR20180089103A (en) * | 2017-01-31 | 2018-08-08 | 현대자동차주식회사 | Steel material for leaf spring and manufacturing method thereof |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
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| KR100847045B1 (en) | 2006-12-27 | 2008-07-17 | 주식회사 포스코 | A high carbon steel sheet superior in yield strength and cold working and manufacturing method thereof |
| CN108265224A (en) * | 2018-03-12 | 2018-07-10 | 富奥辽宁汽车弹簧有限公司 | It is a kind of to be used to manufacture superhigh intensity spring steel of monolithic or few piece changeable section plate spring and preparation method thereof |
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2019
- 2019-12-20 KR KR1020190171858A patent/KR102327929B1/en active IP Right Grant
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- 2020-12-10 WO PCT/KR2020/017990 patent/WO2021125688A1/en unknown
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Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH08302428A (en) * | 1995-05-10 | 1996-11-19 | Nisshin Steel Co Ltd | Production of high strength steel strip for spring |
| JP2007100126A (en) * | 2005-09-30 | 2007-04-19 | Ntn Corp | Rolling member and ball bearing |
| KR101445868B1 (en) * | 2007-06-05 | 2014-10-01 | 주식회사 포스코 | High carbon steel sheet superior in fatiugue lifeand manufacturing method thereof |
| KR20100021273A (en) * | 2008-08-14 | 2010-02-24 | 주식회사 포스코 | High carbon hot rolled steel coil and manufacturing method thereof |
| KR20180089103A (en) * | 2017-01-31 | 2018-08-08 | 현대자동차주식회사 | Steel material for leaf spring and manufacturing method thereof |
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| EP4079908A1 (en) | 2022-10-26 |
| KR20210079746A (en) | 2021-06-30 |
| WO2021125688A1 (en) | 2021-06-24 |
| KR102327929B1 (en) | 2021-11-17 |
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