KR20130046967A - High strength steel sheet have good wear resistant characteristics and method of manufacturing the steel sheet - Google Patents
High strength steel sheet have good wear resistant characteristics and method of manufacturing the steel sheet Download PDFInfo
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- KR20130046967A KR20130046967A KR1020110111666A KR20110111666A KR20130046967A KR 20130046967 A KR20130046967 A KR 20130046967A KR 1020110111666 A KR1020110111666 A KR 1020110111666A KR 20110111666 A KR20110111666 A KR 20110111666A KR 20130046967 A KR20130046967 A KR 20130046967A
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- rolled steel
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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 abstract description 24
- 238000001816 cooling Methods 0.000 claims abstract description 24
- 238000005098 hot rolling Methods 0.000 claims abstract description 15
- 238000003303 reheating Methods 0.000 claims abstract description 14
- 229910052791 calcium Inorganic materials 0.000 claims abstract description 8
- 239000012535 impurity Substances 0.000 claims abstract description 8
- 229910052719 titanium Inorganic materials 0.000 claims abstract description 8
- 229910052726 zirconium Inorganic materials 0.000 claims abstract description 8
- PXHVJJICTQNCMI-UHFFFAOYSA-N nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims description 23
- 239000011572 manganese Substances 0.000 claims description 19
- IJGRMHOSHXDMSA-UHFFFAOYSA-N nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 16
- 239000010949 copper Substances 0.000 claims description 15
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 15
- 239000011575 calcium Substances 0.000 claims description 14
- 239000011651 chromium Substances 0.000 claims description 14
- 239000010955 niobium Substances 0.000 claims description 14
- 239000010936 titanium Substances 0.000 claims description 14
- PWHULOQIROXLJO-UHFFFAOYSA-N manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 claims description 12
- 229910052748 manganese Inorganic materials 0.000 claims description 12
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims description 12
- 229910052710 silicon Inorganic materials 0.000 claims description 12
- 239000010703 silicon Substances 0.000 claims description 12
- OKTJSMMVPCPJKN-UHFFFAOYSA-N carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 11
- 229910052799 carbon Inorganic materials 0.000 claims description 11
- 229910052782 aluminium Inorganic materials 0.000 claims description 10
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminum Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 10
- 229910000734 martensite Inorganic materials 0.000 claims description 9
- GUCVJGMIXFAOAE-UHFFFAOYSA-N niobium Chemical compound [Nb] GUCVJGMIXFAOAE-UHFFFAOYSA-N 0.000 claims description 9
- 229910052758 niobium Inorganic materials 0.000 claims description 9
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 claims description 8
- 229910052796 boron Inorganic materials 0.000 claims description 8
- VYZAMTAEIAYCRO-UHFFFAOYSA-N chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 claims description 8
- RYGMFSIKBFXOCR-UHFFFAOYSA-N copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims description 8
- 229910052802 copper Inorganic materials 0.000 claims description 8
- ZOKXTWBITQBERF-UHFFFAOYSA-N molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 claims description 8
- 229910052750 molybdenum Inorganic materials 0.000 claims description 8
- 239000011733 molybdenum Substances 0.000 claims description 8
- 229910052759 nickel Inorganic materials 0.000 claims description 8
- 229910052757 nitrogen Inorganic materials 0.000 claims description 8
- OAICVXFJPJFONN-UHFFFAOYSA-N phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 claims description 8
- 229910052698 phosphorus Inorganic materials 0.000 claims description 8
- 239000011574 phosphorus Substances 0.000 claims description 8
- NINIDFKCEFEMDL-UHFFFAOYSA-N sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 claims description 8
- 229910052717 sulfur Inorganic materials 0.000 claims description 8
- 239000011593 sulfur Substances 0.000 claims description 8
- OYPRJOBELJOOCE-UHFFFAOYSA-N calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 claims description 7
- 229910052804 chromium Inorganic materials 0.000 claims description 7
- 229910000529 magnetic ferrite Inorganic materials 0.000 claims description 7
- 239000000203 mixture Substances 0.000 claims description 7
- RTAQQCXQSZGOHL-UHFFFAOYSA-N titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 claims description 7
- 229910052720 vanadium Inorganic materials 0.000 claims description 7
- LEONUFNNVUYDNQ-UHFFFAOYSA-N vanadium(0) Chemical compound [V] LEONUFNNVUYDNQ-UHFFFAOYSA-N 0.000 claims description 7
- QCWXUUIWCKQGHC-UHFFFAOYSA-N zirconium Chemical compound [Zr] QCWXUUIWCKQGHC-UHFFFAOYSA-N 0.000 claims description 7
- 229910000859 α-Fe Inorganic materials 0.000 claims description 7
- 229910001563 bainite Inorganic materials 0.000 claims description 6
- 238000005096 rolling process Methods 0.000 claims description 6
- 229910052742 iron Inorganic materials 0.000 claims description 5
- 229910001562 pearlite Inorganic materials 0.000 claims description 5
- 239000002131 composite material Substances 0.000 claims description 3
- 241000894007 species Species 0.000 claims 1
- 238000005299 abrasion Methods 0.000 abstract description 5
- 230000000694 effects Effects 0.000 description 12
- 239000000463 material Substances 0.000 description 7
- 238000000034 method Methods 0.000 description 7
- 238000004804 winding Methods 0.000 description 5
- 229910001566 austenite Inorganic materials 0.000 description 4
- 239000002244 precipitate Substances 0.000 description 3
- 238000005204 segregation Methods 0.000 description 3
- 229910045601 alloy Inorganic materials 0.000 description 2
- 239000000956 alloy Substances 0.000 description 2
- 238000005275 alloying Methods 0.000 description 2
- REDXJYDRNCIFBQ-UHFFFAOYSA-N aluminium(3+) Chemical class [Al+3] REDXJYDRNCIFBQ-UHFFFAOYSA-N 0.000 description 2
- 239000010960 cold rolled steel Substances 0.000 description 2
- 238000005097 cold rolling Methods 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 150000003568 thioethers Chemical class 0.000 description 2
- KSPMJHKUXSQDSZ-UHFFFAOYSA-N [N].[N] Chemical compound [N].[N] KSPMJHKUXSQDSZ-UHFFFAOYSA-N 0.000 description 1
- 230000002159 abnormal effect Effects 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 238000000137 annealing Methods 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000005266 casting Methods 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 230000003111 delayed Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 238000005755 formation reaction Methods 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 230000001771 impaired Effects 0.000 description 1
- 230000002401 inhibitory effect Effects 0.000 description 1
- 239000003562 lightweight material Substances 0.000 description 1
- 230000000670 limiting Effects 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000006011 modification reaction Methods 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- MYMOFIZGZYHOMD-UHFFFAOYSA-N oxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 description 1
- 238000007747 plating Methods 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 238000001953 recrystallisation Methods 0.000 description 1
- 230000002829 reduced Effects 0.000 description 1
- 230000002787 reinforcement Effects 0.000 description 1
- 238000009864 tensile test Methods 0.000 description 1
- 230000001131 transforming Effects 0.000 description 1
- DIMMBYOINZRKMD-UHFFFAOYSA-N vanadium(5+) Chemical compound [V+5] DIMMBYOINZRKMD-UHFFFAOYSA-N 0.000 description 1
Images
Classifications
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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
-
- 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
- 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
-
- 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
- C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
-
- 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
- C22C38/28—Ferrous alloys, e.g. steel alloys containing chromium with titanium or zirconium
-
- 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
- C22C38/38—Ferrous alloys, e.g. steel alloys containing chromium with more than 1.5% by weight of manganese
Abstract
Description
The present invention relates to a high-strength steel sheet manufacturing technology that requires abrasion resistance for automotive parts and heavy equipment parts, and more particularly, excellent weldability through the reduction of alloy components, but excellent wear resistance and ultra high strength of Vickers hardness of 450 Hv or more and tensile strength of 1470 MPa or more. It relates to a hot rolled steel sheet having and a method of manufacturing the same.
The automotive industry is demanding a lightweight material for improved fuel efficiency and CO2 reduction. Accordingly, the steel sheet applied to automobile parts has been intensified in order to reduce weight. In addition, high strength steel sheets having high wear resistance are required in order to prevent the consumption of steel sheets during operation such as cargo compartments, heavy equipment, excavators, etc. of commercial vehicles.
Among automotive parts, materials used for structural members or bumper reinforcement materials are mainly applied to cold rolled steel sheets with a tensile strength of about 590 to 780 MPa. However, in the case of cold rolled steel sheet, other subsequent processes such as a cold rolling process and an annealing treatment process after the hot rolling process are required, resulting in an increase in manufacturing cost. In addition, the development of wear-resistant steel sheet is delayed in the domestic market, and the wear-resistant steel sheet currently depends on all imported materials.
Background art related to the present invention is Republic of Korea Patent Publication No. 10-2002-0046708 (June 21, 2002).
It is an object of the present invention to provide a method for producing a hot rolled steel sheet which can exhibit ultra high strength of 1470 MPa or more in tensile strength without securing cold rolling and heat treatment processes, and can secure abrasion resistance of Vickers hardness (Hv) of 450 or more.
Another object of the present invention is to provide a hot rolled steel sheet having an excellent weldability and an ultra high strength of 1470 MPa or more while providing excellent weldability through reduction of alloying elements.
High-strength hot-rolled steel sheet manufacturing method according to an embodiment of the present invention for achieving the above one object by weight, carbon (C): 0.05 ~ 0.25%, silicon (Si): 0.001 ~ 0.5%, manganese (Mn): 1.0 to 2.0%, aluminum (Al): 0.001 to 0.1%, phosphorus (P): 0.05% or less, sulfur (S): 0.01% or less, nitrogen (N): 0.01% or less and chromium (Cr): 0.01 to 0.5 Reheating the slab plate comprising a%, containing 0.1 to 0.5% in one or more of the sum of titanium (Ti), zirconium (Zr) and calcium (Ca), consisting of the remaining iron (Fe) and unavoidable impurities; Hot rolling the reheated sheet to a finish rolling temperature of 750 to 950 ° C .; And cooling the hot rolled sheet to 300 to 100 ° C. at a cooling rate of 200 to 300 ° C./sec.
High-strength hot-rolled steel sheet according to an embodiment of the present invention for achieving the other object by weight, carbon (C): 0.05 ~ 0.25%, silicon (Si): 0.001 ~ 0.5%, manganese (Mn): 1.0 ~ 2.0 %, Aluminum (Al): 0.001-0.1%, phosphorus (P): 0.05% or less, sulfur (S): 0.01% or less, nitrogen (N): 0.01% or less and chromium (Cr): 0.01-0.5% It comprises 0.1 to 0.5% by adding one or more of titanium (Ti), zirconium (Zr) and calcium (Ca), consisting of the remaining iron (Fe) and inevitable impurities, tensile strength of 1470MPa or more and Vickers hardness ( Hv) 450 or more.
In this case, the steel sheet has a composite structure consisting of a first phase made of martensite and a second phase made of ferrite and bainite, and the first phase may include 80 vol% or more.
In addition, the steel sheet has a composite structure including a first phase made of martensite, a second phase made of ferrite and bainite, and pearlite, wherein the first phase contains 80 vol% or more, and the second phase is less than 20%. It may be included, the pearlite may be included in 5vol% or less.
The steel sheet may have a yield strength of at least 1,000 MPa and an elongation of at least 8%.
The high strength hot rolled steel sheet manufacturing method according to the present invention can produce an ultra high strength hot rolled steel sheet having a tensile strength of 1470 MPa or more through control of an alloy component and a hot rolling process.
In addition, the high-strength hot-rolled steel sheet according to the present invention is characterized by excellent weldability through the reduction of alloying components.
1 is a flow chart showing a high strength hot rolled steel sheet manufacturing method according to an embodiment of the present invention.
Figure 2 is a photograph showing the microstructure for the specimen prepared according to Example 1.
Advantages and features of the present invention, and methods of achieving the same will become apparent with reference to the embodiments described below in detail in conjunction with the accompanying drawings. It should be understood, however, that the invention is not limited to the disclosed embodiments, but is capable of many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, To fully disclose the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims. Like reference numerals refer to like elements throughout the specification.
Hereinafter, a high strength hot rolled steel sheet according to a preferred embodiment of the present invention and a manufacturing method thereof will be described in detail with reference to the accompanying drawings.
High strength hot rolled steel sheet
High strength steel sheet according to the present invention by weight, carbon (C): 0.05 ~ 0.25%, silicon (Si): 0.001 ~ 0.5%, manganese (Mn): 1.0 ~ 2.0%, aluminum (Al): 0.001 ~ 0.1% Phosphorus (P): 0.05% or less, sulfur (S): 0.01% or less, nitrogen (N): 0.01% or less and chromium (Cr): 0.01-0.5%.
In addition, the high strength steel sheet according to the present invention further comprises 0.1 to 0.5% by weight of one or more of titanium (Ti), zirconium (Zr) and calcium (Ca).
In addition, the high strength steel sheet according to the present invention is niobium (Nb): 0.01 to 0.05% by weight, vanadium (V): 0.01 to 0.15% by weight, copper (Cu): 0.1 to 0.5% by weight, nickel (Ni): 0.1 to 0.5 Weight%, boron (B): 0.0005 ~ 0.0030 wt% and molybdenum (Mo): 0.01 ~ 0.15% by weight of one or more of the production method of high strength hot rolled steel sheet characterized in that it further comprises.
In addition to the above components, the remainder consists of iron (Fe) and unavoidable impurities.
Hereinafter, the role and content of each component included in the steel sheet according to the present invention will be described.
Carbon (C)
Carbon (C) is an element that contributes to increasing the strength of steel.
The carbon is preferably added in a content ratio of 0.05 to 0.25% by weight of the total weight of the steel sheet. When the amount of carbon added is less than 0.03% by weight, it is difficult to secure a desired strength. On the contrary, when carbon addition amount exceeds 0.25 weight%, there exists a problem that weldability and toughness fall.
Silicon (Si)
Silicon (Si) contributes to securing strength and also acts as a deoxidizer to remove oxygen in the steel.
The silicon is preferably added in 0.001 to 0.5% by weight of the total weight of the steel sheet. When the amount of silicon added is less than 0.001% by weight, the deoxidation effect and strength improvement effect due to the addition of silicon are insufficient. On the contrary, when the addition amount of silicon exceeds 0.5% by weight, there is a problem that the weldability and plating ability are deteriorated.
Manganese (Mn)
Manganese (Mn) is an element that increases the strength and toughness of steel and increases the ingotability of steel. Addition of manganese causes less deterioration of ductility when strength is increased than that of carbon.
The manganese is preferably added at 1.0 to 2.0% by weight of the total weight of the steel sheet. When the addition amount of manganese is less than 1.0% by weight, the effect of the addition is insufficient. On the other hand, when the addition amount of manganese exceeds 2.0% by weight, MnS-based nonmetallic inclusions are excessively generated, and weldability such as cracking is lowered.
Aluminum (Al)
Aluminum (Al) is added together with silicon to deoxidize the steel.
The aluminum is preferably added in 0.001 to 0.1% by weight of the total weight of the steel sheet. When the addition amount of aluminum is less than 0.001% by weight, the effect of the addition is insufficient. On the contrary, when the addition amount of aluminum exceeds 0.1 weight%, playability may be impaired.
Phosphorus (P)
Phosphorus (P) contributes to the improvement of strength in part, but is an element with a high possibility of segregation in the production of steel sheet, not only the center segregation but also fine segregation, which adversely affects the material, and may also deteriorate weldability.
Therefore, in the present invention, the content of phosphorus was limited to 0.05% by weight or less of the total weight of the steel sheet.
Sulfur (S)
Sulfur (S) combines with manganese to form nonmetallic inclusions such as MnS, which hinders weldability and hinders workability during molding.
Therefore, in the present invention, the content of sulfur is limited to 0.01% by weight or less of the total weight of the steel sheet.
Nitrogen (N)
Nitrogen (N) is an inevitable impurity. If it is contained in a large amount, nitrogen nitrogen is increased and the impact property and elongation rate of the steel sheet are lowered and the toughness of the welded portion is greatly lowered.
Thus, in the present invention, the content of nitrogen was limited to 0.01% by weight or less of the total weight of the steel sheet.
Chrome (Cr)
Chromium (Cr) is included 0.01 ~ 0.5% by weight based on the amount of blast furnace impurities detected. In addition, chromium may be intentionally added for the effect of improving hardenability, and may include 0.05 to 0.1 wt% of the total weight of the steel sheet.
Titanium (Ti), Zirconium (Zr), Calcium (Ca)
The high strength steel sheet according to the present invention may further include at least one of titanium (Ti), zirconium (Zr) and calcium (Ca) for spheroidization of sulfide inclusions, the amount of which is 0.1 to 0.5% by adding one or more of them. Is preferably. When less than 0.1% by weight of the above elements are added, the spheroidizing effect of sulfide inclusions is insufficient. On the contrary, when the elements are added in excess of 0.5% by weight, surface defects, an increase in steel manufacturing cost, and the like may be problematic.
Niobium (Nb), vanadium (V)
Niobium (Nb) and vanadium (V) act effectively to secure strength as a precipitate forming element.
When niobium is added, the content is preferably limited to 0.01 to 0.05% by weight of the total weight of the steel sheet. If the amount of niobium added is less than 0.01% by weight, the effect of adding niobium is insufficient. On the contrary, when the content of niobium exceeds 0.05% by weight, there is a problem in that the workability is lowered by generating a material deviation for each direction of the steel sheet due to an increase in recrystallization temperature.
When the vanadium is added, the content is preferably limited to 0.01 ~ 0.15% by weight of the total weight of the steel sheet. If the amount of vanadium added is less than 0.01% by weight, the effect of addition is insufficient. On the contrary, when the added amount of vanadium exceeds 0.15% by weight, material unevenness and toughness may be reduced due to excessive precipitate formation.
Copper (Cu), Nickel (Ni)
Copper and nickel are elements that improve the hardenability and corrosion resistance of steel.
The copper (Cu) is preferably added at 0.1 to 0.5% by weight of the total weight of the steel sheet. If the content of copper (Cu) is less than 0.1% by weight, the addition effect may not be sufficiently exhibited. On the contrary, when the content of copper (Cu) exceeds 0.5% by weight, there is a problem of lowering the surface properties of the steel.
The nickel (Ni) is preferably added in 0.1 to 0.5% by weight of the total weight of the steel sheet. If the content of nickel (Ni) is less than 0.1% by weight, the effect of the addition can not be exhibited properly. On the contrary, when the content of nickel (Ni) exceeds 0.5% by weight, it causes red light brittleness and increases the manufacturing cost.
Boron (B), Molybdenum (Mo)
Boron (B) and molybdenum (Mo) are hardening enhancement elements, and are effective for producing martensite single phase structures.
When boron is added, the amount is preferably limited to 0.0005 to 0.0030% by weight of the total weight of the steel sheet. When the addition amount of boron is less than 0.0005% by weight, the effect of addition may be insufficient. On the contrary, when the addition amount of boron exceeds 0.0030% by weight, there is a problem of inhibiting the toughness and ductility of the steel.
When molybdenum is added, the addition amount is preferably limited to 0.01 to 0.15% by weight. When the amount of molybdenum added is less than 0.01% by weight, the effect of addition may be insufficient. On the contrary, when molybdenum is added in an amount exceeding 0.15% by weight, the toughness of the steel may be lowered, and the steel sheet manufacturing cost may increase significantly.
High-strength hot-rolled steel sheet according to the present invention having the composition may have a tensile strength of 1470MPa or more and Vickers hardness (Hv) 450 or more by the process conditions described below. This excellent strength and wear resistance can be seen that due to the microstructure of the steel sheet.
The high strength hot rolled steel sheet according to the present invention may have a complex structure consisting of a first phase composed of martensite and residual austenite, and a second phase composed of ferrite and bainite. In this case, 80 vol% or more of the first phase may be included under cooling conditions after hot rolling, in which case it may exhibit high strength and hardness.
In addition, another high-strength hot-rolled steel sheet according to the present invention may include pearlite, in which case the first phase consisting of martensite is included in 80vol% or more, the second phase consisting of ferrite and bainite is contained in less than 20vol%, and pearlite May be included in 5vol% or less.
High strength hot rolled steel sheet manufacturing method
Hereinafter, a high strength hot rolled steel sheet manufacturing method according to the present invention having the above composition will be described.
1 is a flow chart showing a high strength hot rolled steel sheet manufacturing method according to an embodiment of the present invention.
Referring to FIG. 1, the illustrated hot-rolled steel sheet manufacturing method includes a slab reheating step S110, a hot rolling step S120, and a cooling / winding step S130.
Reheat slab
The slab reheating step (S110) re-uses the components and precipitates segregated during casting through reheating of the slab plate in the semi-finished state.
The slab reheating is preferably carried out for approximately 2-4 hours at the slab reheating temperature (SRT) of 1150-1250 ° C. If the slab reheating temperature is less than 1150 ° C, there is a problem that the rolling load is increased because the temperature of the slab plate is low. On the other hand, when the slab reheating temperature exceeds 1250 deg. C, the austenite grains are coarsened and it is difficult to ensure strength.
Hot rolling
In the hot rolling step (S120), the reheated slab plate is hot rolled.
Finish rolling temperature (FDT) in the hot rolling step (S120) is preferably 750 ~ 950 ℃. When hot rolling is finished in the above temperature range, the structure of the steel sheet before cooling after hot rolling may become an austenite phase.
When the finish rolling temperature exceeds 950 ° C austenite grains are coarsened and the ferrite grains are not sufficiently refined after transformation, thereby making it difficult to secure strength. Moreover, when finishing temperature is less than 750 degreeC, problems, such as a mixed structure by abnormal reverse rolling, may arise.
Cooling / winding
In the cooling / winding step (S130), in order to secure a target material, the hot rolled sheet is cooled to 300 ° C. or less at an average cooling rate of 200 ° C./sec or more, and then wound up.
Cooling is preferably carried out at an average cooling rate of 200 ~ 300 ℃ / sec. If the cooling rate is less than 200 ° C / sec, it is difficult to secure the target tensile strength 1470MPa or more and Vickers hardness (Hv) 450 or more. On the contrary, when the cooling rate exceeds 300 ° C / sec, there is a problem that the toughness of the steel sheet is lowered.
It is preferable that cooling completion temperature is 100-300 degreeC. If the winding temperature exceeds 300 ° C., cooling may be insufficient and thus securing sufficient martensite may be difficult. On the contrary, when the coiling temperature is less than 100 ° C, it is difficult to secure an elongation of 8% or more due to excessive cooling.
Example
Hereinafter, the configuration and operation of the present invention through the preferred embodiment of the present invention will be described in more detail. It is to be understood, however, that the same is by way of illustration and example only and is not to be construed in a limiting sense.
Details that are not described herein will be omitted since those skilled in the art can sufficiently infer technically.
1. Preparation of hot-rolled specimens
Hot rolled specimens were prepared with the compositions shown in Tables 1 and 2 and the process conditions described in Table 3.
[Table 1] (unit:% by weight)
[Table 2] (unit:% by weight)
[Table 3]
2. Evaluation of mechanical properties
Table 4 shows the tensile test results for each specimen.
[Table 4]
Referring to Table 4, the specimens according to Examples 1 and 2 that meet the steel composition and process conditions presented in the present invention have a tensile strength of 1470 MPa, yield strength of 1000 MPa or more, elongation of 8% or more, and Vickers hardness (Hv) of 450 or more. You can see that you are satisfied.
In contrast, in the case of Comparative Example 1 in which the steel composition was outside the range set forth in the present invention, the tensile strength and the Vickers hardness fell short of the target values.
In addition, the steel composition satisfies the range set forth in the present invention, but the specimen according to Comparative Example 2 having a relatively low cooling rate and a relatively high cooling end temperature also fell short of the tensile strength and Vickers hardness.
Figure 2 is a photograph showing the microstructure for the specimen prepared according to Example 1.
Referring to FIG. 2, in the case of Specimen 1 according to the Invention Example, it can be seen that the tempered martensite structure is dominant.
While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not limited to the disclosed embodiments. Such changes and modifications are intended to fall within the scope of the present invention unless they depart from the scope of the present invention. Accordingly, the scope of the present invention should be determined by the following claims.
S110: Slab reheating step
S120: Hot rolling step
S130: cooling / winding step
Claims (8)
Hot rolling the reheated sheet to a finish rolling temperature of 750 to 950 ° C .; And
And cooling the hot rolled sheet to 300 to 100 ° C. at a cooling rate of 200 to 300 ° C./sec. 4.
The slab reheating
High strength hot rolled steel sheet manufacturing method characterized in that carried out at 1150 ~ 1250 ℃.
The slab plate is
By weight%, niobium (Nb): 0.01 to 0.05%, vanadium (V): 0.01 to 0.15%, copper (Cu): 0.1 to 0.5%, nickel (Ni): 0.1 to 0.5%, boron (B): 0.0005 ~ 0.0030% and molybdenum (Mo): high strength hot rolled steel sheet manufacturing method characterized in that it further comprises one or more of 0.01 ~ 0.15%.
0.1 to 0.5% by one or more of a combination of titanium (Ti), zirconium (Zr) and calcium (Ca),
Consisting of the remaining iron (Fe) and unavoidable impurities,
A high strength hot rolled steel sheet having a tensile strength of 1470 MPa or more and Vickers hardness (Hv) of 450 or more.
The steel sheet
By weight%, niobium (Nb): 0.01 to 0.05%, vanadium (V): 0.01 to 0.15%, copper (Cu): 0.1 to 0.5%, nickel (Ni): 0.1 to 0.5%, boron (B): 0.0005 ~ 0.0030% and molybdenum (Mo): high strength hot-rolled steel sheet, characterized in that it further comprises one or more of 0.01 ~ 0.15%.
The steel sheet
It has a complex structure consisting of a first phase made of martensite and a second phase made of ferrite and bainite,
High strength hot rolled steel sheet, characterized in that the first phase is contained at least 80vol%.
The steel sheet
A high strength hot rolled steel sheet comprising a composite structure containing 80 vol% or more of the first phase made of martensite, less than 20 vol% of the second phase composed of ferrite and bainite, and 5 vol% or less of pearlite.
The steel sheet
A high strength hot rolled steel sheet having a yield strength of at least 1,000 MPa and an elongation of at least 8%.
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| KR1020110111666A KR20130046967A (en) | 2011-10-28 | 2011-10-28 | High strength steel sheet have good wear resistant characteristics and method of manufacturing the steel sheet |
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| KR1020110111666A KR20130046967A (en) | 2011-10-28 | 2011-10-28 | High strength steel sheet have good wear resistant characteristics and method of manufacturing the steel sheet |
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| KR20130046967A true KR20130046967A (en) | 2013-05-08 |
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP2995696A4 (en) * | 2013-05-09 | 2016-05-18 | Hyundai Steel Co | Hot stamping product with enhanced toughness and method for manufacturing same |
| WO2016100839A1 (en) * | 2014-12-19 | 2016-06-23 | Nucor Corporation | Hot rolled light-gauge martensitic steel sheet and method for making the same |
| WO2018117481A1 (en) * | 2016-12-22 | 2018-06-28 | 주식회사 포스코 | High-hardness wear-resistant steel and method for manufacturing same |
| WO2021017520A1 (en) * | 2019-07-31 | 2021-02-04 | 江阴兴澄特种钢铁有限公司 | Wear-resistant steel with excellent surface quality and preparation method therefor |
| US11332802B2 (en) | 2016-12-22 | 2022-05-17 | Posco | High-hardness wear-resistant steel and method for manufacturing same |
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2011
- 2011-10-28 KR KR1020110111666A patent/KR20130046967A/en not_active Application Discontinuation
Cited By (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP2995696A4 (en) * | 2013-05-09 | 2016-05-18 | Hyundai Steel Co | Hot stamping product with enhanced toughness and method for manufacturing same |
| US9920408B2 (en) | 2013-05-09 | 2018-03-20 | Hyundai Steel Company | Hot stamping product with enhanced toughness and method for manufacturing the same |
| WO2016100839A1 (en) * | 2014-12-19 | 2016-06-23 | Nucor Corporation | Hot rolled light-gauge martensitic steel sheet and method for making the same |
| US20160177411A1 (en) * | 2014-12-19 | 2016-06-23 | Nucor Corporation | Hot rolled light-gauge martensitic steel sheet and method for making the same |
| GB2548049A (en) * | 2014-12-19 | 2017-09-06 | Nucor Corp | Hot rolled light-gauge martensitic steel sheet and method for making the same |
| CN107438487A (en) * | 2014-12-19 | 2017-12-05 | 纽科尔公司 | Light-duty martensite steel plate of hot rolling and preparation method thereof |
| GB2548049B (en) * | 2014-12-19 | 2021-12-29 | Nucor Corp | Hot rolled light-gauge martensitic steel sheet and method for making the same |
| US11225697B2 (en) * | 2014-12-19 | 2022-01-18 | Nucor Corporation | Hot rolled light-gauge martensitic steel sheet and method for making the same |
| WO2018117481A1 (en) * | 2016-12-22 | 2018-06-28 | 주식회사 포스코 | High-hardness wear-resistant steel and method for manufacturing same |
| US11332802B2 (en) | 2016-12-22 | 2022-05-17 | Posco | High-hardness wear-resistant steel and method for manufacturing same |
| US11401572B2 (en) | 2016-12-22 | 2022-08-02 | Posco | High-hardness wear-resistant steel and method for manufacturing same |
| WO2021017520A1 (en) * | 2019-07-31 | 2021-02-04 | 江阴兴澄特种钢铁有限公司 | Wear-resistant steel with excellent surface quality and preparation method therefor |
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