KR101696094B1 - Steel sheet having superior hardness and method for manufacturing the same - Google Patents

Steel sheet having superior hardness and method for manufacturing the same Download PDF

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KR101696094B1
KR101696094B1 KR1020150117985A KR20150117985A KR101696094B1 KR 101696094 B1 KR101696094 B1 KR 101696094B1 KR 1020150117985 A KR1020150117985 A KR 1020150117985A KR 20150117985 A KR20150117985 A KR 20150117985A KR 101696094 B1 KR101696094 B1 KR 101696094B1
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steel sheet
excluding
hot
content
carbon
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임영록
장준상
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주식회사 포스코
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Priority to KR1020150117985A priority Critical patent/KR101696094B1/en
Priority to EP24150998.3A priority patent/EP4324954A3/en
Priority to PCT/KR2016/009079 priority patent/WO2017034216A1/en
Priority to JP2018509544A priority patent/JP6843119B2/en
Priority to EP16839505.1A priority patent/EP3339464A4/en
Priority to CN201680047778.5A priority patent/CN107923023B/en
Priority to US15/751,591 priority patent/US20180237875A1/en
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Publication of KR101696094B1 publication Critical patent/KR101696094B1/en

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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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    • 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
    • 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
    • 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
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
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    • 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
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
    • 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
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/46—Ferrous alloys, e.g. steel alloys containing chromium with nickel with vanadium
    • 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
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/48—Ferrous alloys, e.g. steel alloys containing chromium with nickel with niobium or tantalum
    • 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
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/50—Ferrous alloys, e.g. steel alloys containing chromium with nickel 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
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/54—Ferrous alloys, e.g. steel alloys containing chromium with nickel with boron
    • 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
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/58—Ferrous alloys, e.g. steel alloys containing chromium with nickel with more than 1.5% by weight of manganese
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    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/002—Bainite
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/005—Ferrite
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/008—Martensite

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Abstract

The purpose of an aspect of the present invention is to provide a hard steel sheet with at least 500 HB by forming a composition of the steel sheet based on a minimum carbon content interaction formula to obtain at least 500 HB; and a manufacturing method thereof. The aspect of the present invention relates to the hard steel sheet with at least 500 HB manufactured by performing a process of cooling a hot-rolled steel sheet; and the manufacturing method thereof. The minimum content of carbon (C) satisfies the below interaction formula (1). [Interaction formula 1] (The minimum content of carbon (C)) >= 0.481 - 0.104Mn - 0.035Si - 0.088Cr - 0.054Ni - 0.035Mo - 0.0003C.R. [Here, Mn, Si, Cr, Ni, and Mo are weight percentages for each element content; C.R. are a cooling speed in case of cooling the hot-rolled steel sheet; and a unit thereof is C/sec.]. The hard steel sheet includes a fine structure containing at least 95 vol% of martensitic phases.

Description

고 경도 강판 및 그 제조방법 {STEEL SHEET HAVING SUPERIOR HARDNESS AND METHOD FOR MANUFACTURING THE SAME}TECHNICAL FIELD [0001] The present invention relates to a high hardness steel sheet and a method of manufacturing the same. BACKGROUND ART [0002]

본 발명은 다양한 분야에 사용되는 고 경도 강판 및 그 제조 방법에 관한 것이다.
The present invention relates to a high hardness steel sheet for use in various fields and a manufacturing method thereof.

높은 경도를 갖는 강판은 내마모성과 하중 지탱 능력이 우수하여 긴 사용수명과 내구성을 보장할 수 있으며, 다양한 부품에 사용되고 있다. The steel sheet with high hardness is excellent in abrasion resistance and load supporting ability and can guarantee long service life and durability and is used in various parts.

특히, 내마모강의 경우 브리넬 경도를 기준으로 그 등급이 규정되고 있는데, 통상 HB(브리넬경도) 350급으로부터 높게는 HB 600급까지 다양한 경도 수준으로 제조되고 있다. Particularly, in the case of abrasion resistant steel, its grade is specified on the basis of Brinell hardness, and it is generally manufactured at various hardness levels from HB (brinell hardness) of 350 to HB 600 of high.

또한, 높은 경도를 갖는 강판은 동시에 높은 강도를 가지게 되어 충돌 부재, 보강재와 같이 고강도의 구조를 활용하는 부문에도 사용될 수 있으며 부품 경량화와 효율화 측면에서 높은 경제적 가치를 지니고 있다.In addition, the steel sheet having high hardness has a high strength at the same time, and can be used in a sector that utilizes a high-strength structure such as a collision member and a stiffener, and has economic value in terms of weight reduction and efficiency.

이러한 고 경도 강판은 오스테나이트 온도 영역에서 상온으로의 냉각 과정에서 강판을 마르텐사이트 혹은 베이나이트 조직으로 상 변태시켜 이러한 저온 변태 조직이 갖는 높은 경도와 강도를 활용하는 것이 보통이다.
Such a high hardness steel sheet usually transforms the steel sheet into a martensite or bainite structure during the cooling from the austenite temperature region to the room temperature, and utilizes the high hardness and strength of the low temperature transformation structure.

그러나, 종래 기술은 부품에 따라 요구되는 경도를 얻기 위해 다양한 성분 및 공정 제어의 방안을 동원하고 있으나 일원화된 경도 획득의 기준을 제시하지는 못하고 있다.
The prior art, however, has attempted to use various components and process control schemes to achieve the required hardness according to the component, but fails to provide a standard for obtaining unified hardness.

본 발명의 일 측면은 500HB이상의 브리넬 경도를 얻기 위한 최소 탄소 함량 관계식을 이용하여 강 조성이 설정된 500HB이상의 브리넬 경도를 갖는 고 경도 강판을 제공하고자 하는 것이다.
One aspect of the present invention is to provide a high hardness steel sheet having a Brinell hardness of 500 HB or more and having a steel composition set by using a minimum carbon content relation for obtaining a Brinell hardness of 500 HB or more.

본 발명의 다른 일 측면은 500HB이상의 브리넬 경도를 얻기 위한 최소 탄소 함량 관계식에 따라 강 조성을 설정하여 500HB이상의 브리넬 경도를 갖는 고 경도 강판을 제조하는 방법을 제공하고자 하는 것이다.
Another aspect of the present invention is to provide a method of manufacturing a high hardness steel sheet having a Brinell hardness of 500HB or more by setting a steel composition according to a minimum carbon content relation for obtaining a Brinell hardness of 500HB or more.

본 발명의 바람직한 일 측면은 열간압연된 열연강판을 냉각하는 공정을 포함하여 제조되는 강판으로서, According to a preferred aspect of the present invention, there is provided a steel sheet comprising a step of cooling a hot-rolled steel sheet,

중량%로, 탄소(C): 0.05 ~ 0.3wt%, 규소(Si): 0.5%이하(0%는 제외), 망간(Mn): 2.5% 이하(0%는 제외), 크롬(Cr): 1.5% 이하(0%는 제외), 몰리브덴(Mo): 1.0%이하(0%는 제외), 니켈(Ni): 1.0% 이하(0%는 제외), 니오비움(Nb): 0.1% 이하(0%는 제외), 타이타니움(Ti): 0.1% 이하(0%는 제외), 바나디움(V): 0.1% 이하(0%는 제외), 보론(B): 0.01% 이하(0%는 제외), 알루미늄(Al): 0.1% 이하(0%는 제외), 잔부 철(Fe) 및 기타 불가피한 불순물로 이루어지고;(C): 0.05 to 0.3% by weight, Si: 0.5% or less (excluding 0%), manganese (Mn): not more than 2.5% Not more than 1.5% (excluding 0%), molybdenum (Mo): not more than 1.0% (excluding 0%), nickel (Ni): not more than 1.0% (excluding 0%) and niobium (Excluding 0%), titanium (Ti): not more than 0.1% (excluding 0%), vanadium (V): not more than 0.1% (Al): not more than 0.1% (excluding 0%), the balance iron (Fe) and other unavoidable impurities;

상기 탄소(C)의 최소 함량은 하기 관계식(1)을 만족하고;The minimum content of carbon (C) satisfies the following relational expression (1);

[관계식 1][Relation 1]

C(탄소(C)의 최소 함량)≥ 0.481-0.104Mn-0.035Si-0.088Cr-0.054Ni-0.035Mo-0.0003C.R.C (minimum content of carbon (C))? 0.481-0.104Mn-0.035Si-0.088Cr-0.054Ni-0.035Mo-0.0003C.R.

[여기서, Mn, Si, Cr, Ni 및 Mo은 각 원소들의 함유량을 중량%로 나타낸 값이고, C.R.은 열연강판의 냉각 시 냉각속도를 나타낸 값이고, 단위는 ℃/sec임]Wherein the contents of Mn, Si, Cr, Ni, and Mo are expressed in weight%, C.R. is a value indicating a cooling rate during cooling of the hot-rolled steel sheet, and the unit is ° C / sec.

95vol.% 이상의 마르텐사이트 상을 포함하는 미세조직을 갖고; 그리고 At least 95 vol.% Of a martensite phase; And

500HB이상의 브리넬 경도를 갖는 고 경도 강판에 관한 것이다.
Hardness steel having a Brinell hardness of 500HB or more.

본 발명의 바람직한 다른 일 측면은 중량%로, 탄소(C): 0.05 ~ 0.3wt%, 규소(Si): 0.5%이하(0%는 제외), 망간(Mn): 2.5% 이하(0%는 제외), 크롬(Cr): 1.5% 이하(0%는 제외), 몰리브덴(Mo): 1.0% 이하(0%는 제외), 니켈(Ni): 1.0%이하(0%는 제외), 니오비움(Nb): 0.1% 이하(0%는 제외), 타이타니움(Ti): 0.1% 이하(0%는 제외), 바나디움(V): 0.1% 이하(0%는 제외), 보론(B): 0.01% 이하(0%는 제외), 알루미늄(Al): 0.1% 이하(0%는 제외), 잔부 철(Fe) 및 기타 불가피한 불순물로 이루어지는 강 슬라브를 열연강판으로 열간압연한 후, 냉각시켜 95vol.% 이상의 마르텐사이트 상을 포함하는 미세조직 및 500HB이상의 브리넬 경도를 갖는 강판을 제조하는 방법으로서, 상기 탄소(C)의 최소 함량은 하기 관계식(1)을 만족하는 고 경도 강판의 제조방법에 관한 것이다.Another preferred aspect of the present invention is a steel sheet comprising 0.05 to 0.3% by weight of carbon (C), 0.5% or less (excluding 0%) of manganese (Mn) 1.0% or less (excluding 0%), nickel (Ni): not more than 1.0% (excluding 0%), chromium (Cr) 0.1% or less (excluding 0%), titanium (Ti): 0.1% or less (excluding 0%), vanadium (V) : Steel slabs composed of not more than 0.01% (excluding 0%), aluminum (Al): not more than 0.1% (excluding 0%), the balance iron (Fe) and other unavoidable impurities are hot rolled into hot rolled steel sheets, A method for producing a steel sheet having a microstructure comprising 95 vol% or more of martensite phase and a Brinell hardness of 500HB or more, wherein a minimum content of carbon (C) satisfies the following relational expression (1) .

[관계식 1][Relation 1]

C(탄소(C)의 최소 함량)≥ 0.481-0.104Mn-0.035Si-0.088Cr-0.054Ni-0.035Mo-0.0003C.R.C (minimum content of carbon (C))? 0.481-0.104Mn-0.035Si-0.088Cr-0.054Ni-0.035Mo-0.0003C.R.

[여기서, Mn, Si, Cr, Ni 및 Mo은 각 원소들의 함유량을 중량%로 나타낸 값이고, C.R.은 열연강판의 냉각 시 냉각속도를 나타낸 값이고, 단위는 ℃/sec임]
Wherein the content of Mn, Si, Cr, Ni and Mo is expressed in weight%, CR is a value indicating the cooling rate during cooling of the hot-rolled steel sheet, and the unit is ° C / sec.

본 발명의 일 측면에 의하면, 95vol.% 이상 마르텐사이트 상을 포함하는 미세조직 및 500HB이상의 브리넬 경도를 갖는 강판 제조를 위한 보다 경제적이고 일원화된 강판의 성분 설계를 가능하게 하는 효과가 있다.
According to an aspect of the present invention, it is possible to design a more economical and unified steel sheet component for producing a microstructure containing 95 vol% or more of martensite phase and a steel sheet having a Brinell hardness of 500 HB or more.

고 경도 강판과 관련되는 종래 기술은 부품에 따라 요구되는 경도를 얻기 위하여 다양한 성분 및 공정 제어의 방안을 제안하고 있으나 일원화된 경도 획득의 성분 기준 등을 제시하지는 못하고 있다.
The prior art relating to high hardness steel sheets has proposed various components and process control methods to obtain the required hardness according to the parts, but fails to provide the standard of composition hardness acquisition.

이에 , 본 발명자들은 높은 경도와 강도를 확보하기 위하여 강판의 미세조직을 95vol.% 이상의 마르텐사이트 조직으로 형성할 때, 필요한 경도 수준을 확보하기 위한 성분 설계의 조건 등에 대하여 연구 및 실험을 행하고, 그 결과에 기초하여 본 발명을 완성하기에 이른 것이다.Accordingly, the present inventors conducted research and experiments on the conditions of component design for securing the necessary hardness level when forming the microstructure of the steel sheet into a martensite structure of 95 vol% or more in order to secure high hardness and strength, Based on the results, the present invention has been completed.

즉, 본 발명의 주요 기술적 사상 중의 하나는 높은 경도와 강도를 확보하기 위하여 강판의 미세조직을 95vol.% 이상의 마르텐사이트 조직으로 형성할 때, 필요한 경도 수준을 확보하기 위한 성분 설계의 조건을 제시하여 95vol.% 이상 마르텐사이트 상을 포함하는 미세조직 및 500HB이상의 브리넬 경도를 갖는 강판을 보다 경제적으로 제조할 수 있고, 또한 일원화된 경도를 얻을 수 있는 것이다.
That is, one of the main technical ideas of the present invention is to provide a condition of component design for securing the necessary hardness level when forming the microstructure of the steel sheet into the martensite structure of 95 vol% or more in order to secure high hardness and strength A steel sheet having a microstructure containing 95 vol% or more of martensite phase and a Brinell hardness of 500 HB or more can be produced more economically and a unified hardness can be obtained.

이하, 본 발명의 바람직한 일 측면에 따르는 강판에 대하여 설명한다.
Hereinafter, a steel sheet according to a preferred aspect of the present invention will be described.

탄소(C): 0.05 ~ 0.3중량%(이하, "%"라고 침함)Carbon (C): 0.05 to 0.3% by weight (hereinafter referred to as "%"),

탄소(C)의 함량은 0.05 ~ 0.3%일 수 있다. The content of carbon (C) may be 0.05 to 0.3%.

탄소의 함량이 0.05% 미만인 경우 오스테나이트 영역으로부터 냉각 시 마르텐사이트 변태가 일어나기 어려울 수 있고, 또한, 탄소의 함량이 0.3%를 초과하는 경우, 강재의 취약성이 증가하여 부품의 안정성을 보장하기 어려울 수 있다.
If the content of carbon is less than 0.05%, it may be difficult to cause martensite transformation upon cooling from the austenite region. If the content of carbon exceeds 0.3%, the vulnerability of the steel increases, have.

규소(Si): 0.5%이하(0%는 제외)Silicon (Si): 0.5% or less (excluding 0%)

규소(Si)의 함량은 0.5%이하(0%는 제외)일 수 있다. The content of silicon (Si) may be 0.5% or less (excluding 0%).

규소는 강재의 내마모성을 증가시키기 때문에 경도를 활용하는 용도에서 선호되는 합금 원소이다. 다만 Si가 지나치게 많이 첨가되면 강재의 표면 특성 및 도금성이 나빠지고 재가열시 완전한 오스테나이트화가 이루어지지 않을 가능성이 있다.
Silicon is the preferred alloying element in applications that use hardness because it increases the abrasion resistance of steels. However, if too much Si is added, the surface properties and plating properties of the steel become poor, and a complete austenitization may not be achieved during reheating.

망간(Mn): 2.5% 이하(0%는 제외) 및 크롬(Cr): 1.5% 이하(0%는 제외)Manganese (Mn): 2.5% or less (excluding 0%) and chromium (Cr): 1.5% or less (excluding 0%)

망간(Mn)과 크롬(Cr)은 모두 마르텐사이트 변태점을 크게 낮추는 원소로서, 망간과 크롬은 통상적으로 강에 첨가되는 원소 중 탄소 다음으로 변태점 저하의 효과가 크고 저가의 원소로서 경제적으로 활용이 가능한 원소이다. Both manganese (Mn) and chromium (Cr) are elements that greatly lower the transformation point of martensite. Manganese and chromium are usually added to the steel after the carbon, and the effect of lowering the transformation point is great. It is an element.

상기 망간 함량의 상한은 2.5%로 제한하는 것이 바람직하고, 상기 크롬 함량의 상한은 1.5%로 제한하는 것이 바람직하다. The upper limit of the manganese content is preferably limited to 2.5%, and the upper limit of the chromium content is preferably limited to 1.5%.

상기 망간과 크롬의 함량이 지나치게 높을 경우에는 오스테나이트가 상온에서 잔류하게 되어 목표하는 95vol.% 이상의 마르텐사이트 조직을 얻을 수 없게 될 우려가 있다.
If the content of manganese and chromium is too high, the austenite will remain at room temperature, and there is a possibility that a desired martensite structure of 95 vol% or more can not be obtained.

몰리브덴(Mo): 1.0% 이하(0%는 제외) 및 니켈(Ni): 1.0% 이하(0%는 제외)Molybdenum (Mo): not more than 1.0% (excluding 0%) and nickel (Ni): not more than 1.0% (excluding 0%)

몰리브덴(Mo)과 니켈(Ni)은 마르텐사이트 변태개시온도를 낮추는 원소이다Molybdenum (Mo) and nickel (Ni) are elements that lower the martensitic transformation starting temperature

그러나, 마르텐사이트 변태개시온도를 낮추는 정도는 Mn과 Cr 보다는 낮으며, 고가의 원소로서 이들 원소의 첨가량의 상한은 각각 1.0%로 제한하는 것이 바람직하다.
However, the degree of lowering the martensitic transformation starting temperature is lower than that of Mn and Cr, and the upper limit of the addition amount of these elements as the expensive elements is preferably limited to 1.0%.

니오비움(Nb): 0.1% 이하(0%는 제외) 및 타이타니움(Ti): 0.1% 이하(0%는 제외), Niobium (Nb): 0.1% or less (excluding 0%) and titanium (Ti): 0.1% or less (excluding 0%),

니오비움(Nb)과 타이타니움(Ti)은 각각 0.1% 이하(0%는 제외)의 수준으로 첨가할 수 있으며, 오스테나이트 결정립 미세화를 통해 강판의 충격 특성을 개선하는 효과가 있다. 하지만, 지나친 Nb 및 Ti의 첨가는 결정립 경계를 고정하는 Nb 탄질화물의 조대화를 야기하여 결정립 미세화 효과를 상실하게 되므로, 그 상한은 각각 0.1%로 한정하는 것이 바람직하다. Niobium (Nb) and titanium (Ti) can be added at a level of 0.1% or less (excluding 0%), respectively, and the effect of improving the impact characteristics of the steel sheet through microfine austenite grains is effective. However, excessive addition of Nb and Ti causes coarsening of the Nb carbonitride that fixes the grain boundary, thereby losing grain refinement effect, and therefore the upper limit is preferably limited to 0.1% each.

한편, Ti은 B을 첨가할 경우 B을 N로부터 보호하기 위해 필수적으로 첨가하는 경우가 많으며, 티타늄(Ti)은 강 중의 탄소 또는 질소와 먼저 반응하여 TiC 또는 TiN을 형성함으로써 붕소(B)의 첨가 효과를 높인다. 이 경우, 티타늄(Ti)의 함량은 강 중 질소량과의 화학양론에 의해 하기의 관계식 2를 만족하면 충분하다.On the other hand, Ti is often added to protect B from N when B is added, and titanium (Ti) reacts first with carbon or nitrogen in the steel to form TiC or TiN, so that addition of boron (B) Increase effect. In this case, it is sufficient that the content of titanium (Ti) satisfies the following relational expression 2 depending on the stoichiometry with respect to the nitrogen content in the steel.

[관계식 2][Relation 2]

Ti(wt%) > N(wt%) × 3.42
Ti (wt%) > N (wt%) x 3.42

바나디움(V): 0.1% 이하(0%는 제외)Vanadium (V): 0.1% or less (excluding 0%)

바나디움(V)은 0.1% 이하(0%는 제외)의 수준으로 첨가할 수 있으며, 미세한 V 탄화물의 형성을 통한 석출경화 및 용접부 물성 저하를 막는 역할을 한다. The vanadium (V) can be added at a level of 0.1% or less (excluding 0%), and serves to prevent precipitation hardening and deterioration of the properties of the welded part through formation of fine V carbide.

그 첨가량이 지나치게 많을 경우에는 탄화물의 조대화로 인해 그 효과가 감소하므로 그 함량의 상한은 0.1%로 제한하는 것이 바람직하다.
If the addition amount is too large, the effect is reduced due to the coarsening of the carbide, so that the upper limit of the content is preferably limited to 0.1%.

보론(B): 0.01% 이하(0%는 제외)Boron (B): 0.01% or less (excluding 0%)

보론(B)은 0.01% 이하(0%는 제외)의 수준으로 첨가할 수 있으며, B은 페라이트 및 퍼얼라이트의 핵생성을 저해하여 강재의 경화능을 대폭 향상시키는 원소로서, 강재의 두께가 두꺼울 경우에 그 활용도가 매우 크다. Boron (B) can be added at a level of 0.01% or less (excluding 0%), and B is an element which significantly inhibits the nucleation of ferrite and pearlite and greatly improves the hardenability of the steel. The utilization is very high.

본 발명에서는 최종 미세조직을 95vol.% 이상의 마르텐사이트로 얻는데 그 제조 과정에 대한 특별한 제약은 없고 따라서 B은 필요에 따라 경화능 확보를 위해 첨가할 수 있다. 다만 B의 함량은 지나치게 첨가될 경우 오히려 페라이트나 퍼얼라이트 상의 핵생성 자리로서 작용하여 경화능을 해치게 되므로 그 함량의 상한은 0.01%로 제한하는 것이 바람직하다.
In the present invention, the final microstructure is obtained with at least 95 vol.% Of martensite. There is no particular restriction on the production process thereof, and thus B can be added for securing curing ability if necessary. However, when the content of B is excessively added, it functions as a nucleus generation site on the ferrite or pearlite, thereby deteriorating the hardenability. Therefore, the upper limit of the content is preferably limited to 0.01%.

알루미늄(Al): 0.1% 이하(0%는 제외)Aluminum (Al): 0.1% or less (excluding 0%)

알루미늄(Al)은 탈산과 결정립 미세화를 위해 첨가하며, 그 함량은 0.1% 이하(0%는 제외)로 제한하는 것이 바람직하다.
Aluminum (Al) is added for deoxidation and grain refinement, and its content is preferably limited to 0.1% or less (excluding 0%).

전술한 원소들을 제외한 나머지는 철(Fe) 및 기타 불가피한 불순물을 포함한다.
The remainder excluding the above-mentioned elements include iron (Fe) and other unavoidable impurities.

본 발명에서는 상기 탄소(C)의 최소 함량은 하기 관계식(1)을 만족한다.In the present invention, the minimum content of carbon (C) satisfies the following relational expression (1).

[관계식 1][Relation 1]

C(탄소(C)의 최소 함량)≥ 0.481-0.104Mn-0.035Si-0.088Cr-0.054Ni-0.035Mo-0.0003C.R.C (minimum content of carbon (C))? 0.481-0.104Mn-0.035Si-0.088Cr-0.054Ni-0.035Mo-0.0003C.R.

[여기서, Mn, Si, Cr, Ni 및 Mo은 각 원소들의 함유량을 중량%로 나타낸 값이고, C.R.은 열연강판의 냉각 시 냉각속도를 나타낸 값이고, 단위는 ℃/sec임]
Wherein the content of Mn, Si, Cr, Ni and Mo is expressed in weight%, CR is a value indicating the cooling rate during cooling of the hot-rolled steel sheet, and the unit is ° C / sec.

상기 관계식(1)은 상기 규소(Si), 망간(Mn), 크롬(Cr), 몰리브덴(Mo), 니켈(Ni) 및 크롬(Cr)의 조성으로부터 500HB이상의 브리넬 경도를 얻기 위한 최소 탄소(C) 함량을 나타낸다.The relational expression (1) is defined as the minimum carbon (C) for obtaining a Brinell hardness of 500 HB or more from the composition of the silicon (Si), manganese (Mn), chromium (Cr), molybdenum (Mo), nickel (Ni) ) Content.

상기 탄소(C)함량이 0.05 ~ 0.3중량%를 만족한다고 하더라도 상기 관계식(1)을 만족시키지 못하면 500HB이상의 브리넬 경도를 얻을 수 없다.
Even if the carbon (C) content satisfies 0.05 to 0.3 wt%, the Brinell hardness of 500 HB or more can not be obtained unless the above relation (1) is satisfied.

상기 관계식(1)은 예를 들면, 하기 관계식(3)을 이용하여 설계될 수 있다.
The above relational expression (1) can be designed using, for example, the following relational expression (3).

[관계식 3][Relation 3]

HB (브리넬 경도) = 100.4 + 830.5*C + 86.5*Mn + 28.8*Si + 73.4*Cr + HB = Brinell Hardness = 100.4 + 830.5 * C + 86.5 * Mn + 28.8 * Si + 73.4 * Cr +

44.5*Ni + 28.8*Mo + 0.252*C.R.44.5 * Ni + 28.8 * Mo + 0.252 * C.R.

[여기서, C, Mn, Si, Cr, Ni 및 Mo은 각 원소들의 함유량을 중량%로 나타낸 값이고, C.R.은 열연강판의 냉각 시 냉각속도를 나타낸 값이고, 단위는 ℃/sec임]
Wherein CR, Mn, Si, Cr, Ni and Mo are values indicating the content of each element in weight%, CR is a value indicating cooling rate during cooling of the hot-rolled steel sheet,

상기 관계식(3)으로부터 HB ≥500이기 위한 최소 탄소 함량에 대한 관계식 (1)이 도출될 수 있다.
From the above relationship (3), a relational expression (1) for the minimum carbon content for HB ≥ 500 can be derived.

또한, 본 발명의 강판 성분 범위 내에서 관계식(3)를 이용함으로써 HB 350 이상의 어떠한 필요 경도 수준을 얻기 위한 적정 합금 성분 설계조건을 도출할 수도 있다.In addition, by using the relationship (3) within the range of the steel sheet composition of the present invention, it is possible to derive a suitable alloy component designing condition for obtaining any required hardness level of HB 350 or more.

본 발명의 강판의 미세조직은 95vol.% 이상의 마르텐사이트 상을 포함한다.The microstructure of the steel sheet of the present invention contains 95 vol% or more of martensite phase.

상기 마르텐사이트 상의 분율이 95vol.% 미만인 경우에는 목적하는 강도 및 경도를 확보하기 어려울 수 있다.When the fraction of the martensite phase is less than 95 vol.%, It may be difficult to secure the desired strength and hardness.

본 발명의 강판의 미세조직은 마르텐사이트 이외의 제2상 조직으로 5.0vol.% 미만의 페라이트 및 베이나이트 중 1 종 또는 2종을 포함할 수 있다.
The microstructure of the steel sheet of the present invention may include one or two kinds of ferrite and bainite having a second phase structure other than martensite and less than 5.0 vol%.

본 발명의 강판은 500HB이상의 브리넬 경도를 갖는다.
The steel sheet of the present invention has a Brinell hardness of 500HB or more.

이하, 본 발명의 바람직한 다른 일 측면에 따르는 강판의 제조방법에 대하여 설명한다.
Hereinafter, a method for manufacturing a steel sheet according to another preferred embodiment of the present invention will be described.

본 발명의 바람직한 다른 일 측면에 따르는 강판의 제조방법에서는 중량%로, 탄소(C): 0.05 ~ 0.3wt%, 규소(Si): 0.5%이하(0%는 제외), 망간(Mn): 2.5% 이하(0%는 제외), 크롬(Cr): 1.5% 이하(0%는 제외), 몰리브덴(Mo): 1.0% 이하(0%는 제외), 니켈(Ni): 1.0%이하(0%는 제외), 니오비움(Nb): 0.1% 이하(0%는 제외), 타이타니움(Ti): 0.1% 이하(0%는 제외), 바나디움(V): 0.1% 이하(0%는 제외), 보론(B): 0.01% 이하(0%는 제외), 알루미늄(Al): 0.1% 이하(0%는 제외), 잔부 철(Fe) 및 기타 불가피한 불순물로 이루어지는 강 슬라브를 열연강판으로 열간압연한 후, 냉각시켜 95vol.% 이상의 마르텐사이트 상을 포함하는 미세조직 및 500HB이상의 브리넬 경도를 갖는 강판을 제조한다.
In a steel sheet manufacturing method according to another preferred aspect of the present invention, 0.05 to 0.3% by weight of carbon (C), 0.5% or less of silicon (excluding 0%), manganese (Mn) Mo content: not more than 1.0% (excluding 0%), nickel (Ni): not more than 1.0% (excluding 0%), 0.1% or less (excluding 0%), titanium (Ti): 0.1% or less (excluding 0%), vanadium (V): 0.1% or less ), Boron (B): not more than 0.01% (excluding 0%), aluminum (Al): not more than 0.1% (excluding 0%), iron (Fe) and other unavoidable impurities is hot rolled Rolled and then cooled to prepare a steel sheet having a microstructure containing 95 vol% or more of martensite phase and having a Brinell hardness of 500 HB or more.

상기 강 슬라브의 탄소(C)의 최소 함량은 하기 관계식(1)을 만족한다.The minimum content of carbon (C) in the steel slab satisfies the following relational expression (1).

[관계식 1][Relation 1]

C(탄소(C)의 최소 함량)≥ 0.481-0.104Mn-0.035Si-0.088Cr-0.054Ni-0.035Mo-0.0003C.R.C (minimum content of carbon (C))? 0.481-0.104Mn-0.035Si-0.088Cr-0.054Ni-0.035Mo-0.0003C.R.

[여기서, Mn, Si, Cr, Ni 및 Mo은 각 원소들의 함유량을 중량%로 나타낸 값이고, C.R.은 열연강판의 냉각 시 냉각속도를 나타낸 값이고, 단위는 ℃/sec임]
Wherein the content of Mn, Si, Cr, Ni and Mo is expressed in weight%, CR is a value indicating the cooling rate during cooling of the hot-rolled steel sheet, and the unit is ° C / sec.

상기 강 슬라브를 열연강판으로 열간압연하기 전에, 강 슬라브를 재가열 할 수 있다. The steel slab can be reheated before hot rolling the steel slab to the hot-rolled steel sheet.

슬라브 재가열 조건은 특별히 한정되는 것은 아니며, 균질화가 이루어지면 충분하다. The conditions for reheating the slab are not particularly limited, and homogenization is sufficient.

슬라브 재가열 온도는 1100 ~ 1300℃가 바람직하다.The slab reheating temperature is preferably 1100 to 1300 ° C.

상기 열간압연 조건은 특별히 한정되는 것은 아니며, 열간 마무리압연 온도는 오스테나이트화가 충분히 이루어지는 온도이면 충분하다.The hot rolling condition is not particularly limited, and the hot finish rolling temperature may be a temperature at which austenitization is sufficiently performed.

상기 열간 마무리압연 온도는 예를 들면, 870 ~ 930℃일 수 있으며, 전체 열간압연은 가열로 추출 후 1150℃ ~ 열간 마무리압연 온도의 온도 범위에서 이루어질 수 있다.The hot finish rolling temperature may be, for example, 870 to 930 캜, and the whole hot rolling may be performed in a temperature range of 1150 캜 to a hot finish rolling temperature after extraction by heating.

상기 열연강판의 냉각 시 냉각속도는 95vol.% 이상의 마르텐사이트 상을 얻을 수 있는 냉각속도라면 특별히 한정되는 것은 아니며, 예를 들면, 20℃/sec이상, 바람직하게는 20~150℃/sec이다.
The cooling rate during cooling of the hot-rolled steel sheet is not particularly limited as long as it is a cooling rate at which a martensite phase of 95 vol% or more can be obtained. For example, it is 20 ° C / sec or more, preferably 20 to 150 ° C / sec.

상기 열연강판의 냉각 시 냉각 종료온도는 Ms 점(마르텐사이트 변태시작온도)이하이며, 95vol.% 이상의 마르텐사이트 상을 얻을 수 있는 온도라면 특별히 한정되는 것은 아니다.
The cooling end temperature at the time of cooling of the hot-rolled steel sheet is not particularly limited as long as it is not higher than the Ms point (martensitic transformation starting temperature) and can obtain a martensite phase of 95 vol% or more.

이하, 실시예를 통하여 본 발명을 보다 구체적으로 설명한다. 이러한 실시예는 단지 본 발명을 예시하기 위한 것이며, 본 발명이 여기에 한정되는 것은 아니다.
Hereinafter, the present invention will be described more specifically by way of examples. These embodiments are only for illustrating the present invention, and the present invention is not limited thereto.

(실시예)(Example)

하기 표 1의 조성을 갖는 A 내지 Q의 17종류의 강들을 사용하여 실험하였다Experiments were conducted using 17 kinds of steels A to Q having the composition shown in Table 1 below

하기의 표 1의 강들의 조성은 모두 본 발명의 조성 범위를 만족한다.The compositions of the steels shown in Table 1 below all satisfy the composition ranges of the present invention.

하기 표 1의 강 조성을 갖고 두께 30mm 및 폭 200mm인 강판을 제조한 후, 1200℃에서 180분간 재가열하였다. 다음에, 재가열된 강판을 900℃의 열간 마무리 온도 범위에서 열간 압연하여 그 두께가 3.0mm인 열연강판을 제조한 후, 200℃까지 하기 표 2의 냉각속도로 냉각하였다. A steel sheet having a thickness of 30 mm and a width of 200 mm having a steel composition shown in Table 1 below was prepared and reheated at 1200 ° C for 180 minutes. Next, the reheated steel sheet was hot rolled in a hot finish temperature range of 900 占 폚 to produce a hot rolled steel sheet having a thickness of 3.0 mm, and then cooled to 200 占 폚 at the cooling rate shown in Table 2 below.

상기와 같이 제조된 열연강판의 브리넬 경도(HB) 및 미세조직을 측정하고, 그 결과를 하기 표 2에 나타내었다. The Brinell hardness (HB) and microstructure of the hot-rolled steel sheet thus prepared were measured, and the results are shown in Table 2 below.

하기 표 2에는 마르텐사이트를 제외한 제2상 조직을 나타낸 것으로, 제2상 외의 조직은 마르텐사이트이다.Table 2 below shows a second phase structure excluding martensite, and the second phase is martensite.

하기 제2상 조직에서 F는 페라이트를 나타내고, B는 베이나이트를 나타내고, M은 마르텐사이트를 나타낸다.In the following second phase structure, F represents ferrite, B represents bainite, and M represents martensite.

또한, 하기 표 2에는 관계식 (1)에 의해 구해진 필요 탄소함량, 실제 탄소함량 및 실제 탄소함량과 필요 탄소함량의 차이를 함께 나타내었다.
Table 2 also shows the difference between the required carbon content, the actual carbon content, and the actual carbon content and the required carbon content determined by the relational expression (1).

강종Steel grade CC SiSi MnMn CrCr MoMo NiNi AlAl TiTi NbNb VV B
B
AA 0.0810.081 0.2980.298 1.851.85 0.4980.498 0.1010.101 0.0080.008 0.030.03 0.0060.006 0.0320.032 0.0060.006 0.00020.0002 BB 0.1210.121 0.3510.351 2.112.11 0.3130.313 0.7980.798 0.0120.012 0.0320.032 0.0250.025 0.0230.023 0.0050.005 0.00170.0017 CC 0.1950.195 0.3540.354 2.012.01 0.2970.297 0.0060.006 0.8120.812 0.0310.031 0.0290.029 0.0250.025 0.0030.003 0.00160.0016 DD 0.1520.152 0.2480.248 1.491.49 0.2960.296 0.0080.008 0.0110.011 0.0330.033 0.030.03 0.0560.056 0.0050.005 0.0030.003 EE 0.2420.242 0.4320.432 1.721.72 0.4110.411 0.3120.312 0.0130.013 0.0360.036 0.030.03 0.0030.003 0.0060.006 0.00330.0033 FF 0.1480.148 0.2430.243 1.481.48 0.6070.607 0.0120.012 0.0050.005 0.0340.034 0.0290.029 0.0040.004 0.0040.004 0.00320.0032 GG 0.1480.148 0.240.24 1.481.48 0.30.3 0.0070.007 0.0070.007 0.0350.035 0.0980.098 0.0050.005 0.0050.005 0.00330.0033 HH 0.2970.297 0.2530.253 1.511.51 0.30.3 0.2110.211 0.0060.006 0.0350.035 0.030.03 0.0070.007 0.0020.002 0.00160.0016 II 0.2120.212 0.250.25 1.491.49 1.11.1 0.2030.203 0.0080.008 0.0350.035 0.030.03 0.0220.022 0.0980.098 0.00290.0029 JJ 0.20.2 0.2490.249 1.471.47 0.30.3 0.0110.011 0.0210.021 0.030.03 0.0290.029 0.0050.005 0.0030.003 0.00290.0029 KK 0.2520.252 0.2540.254 2.312.31 0.1250.125 0.0120.012 0.0150.015 0.0330.033 0.030.03 0.0320.032 0.0050.005 0.00280.0028 LL 0.1980.198 0.2430.243 1.491.49 0.2970.297 0.0150.015 0.0230.023 0.0340.034 0.030.03 0.0080.008 0.0040.004 0.00310.0031 MM 0.1990.199 0.2540.254 1.471.47 1.121.12 0.0120.012 0.0150.015 0.0330.033 0.030.03 0.0320.032 0.0050.005 0.00280.0028 NN 0.20.2 0.2070.207 1.471.47 0.30.3 0.0110.011 0.0140.014 0.0340.034 0.0980.098 0.0450.045 0.0020.002 0.00250.0025 OO 0.260.26 0.2970.297 2.112.11 0.020.02 0.1010.101 0.0050.005 0.0270.027 0.0070.007 0.0220.022 0.0110.011 0.00030.0003 PP 0.270.27 0.2120.212 1.511.51 0.520.52 0.1120.112 0.0120.012 0.0210.021 0.0050.005 0.0230.023 0.0120.012 0.00200.0020 QQ 0.2320.232 0.4910.491 1.781.78 0.2980.298 0.0050.005 0.0030.003 0.0260.026 0.0210.021 0.0150.015 0.0550.055 0.00180.0018

구분division 강종Steel grade Ms
(℃)Ms
(° C) 냉각속도
(℃/sec)Cooling rate
(° C / sec) 필요 탄소함량
(wt.%,관계식1)
①Required carbon content
(wt.%, relational expression 1)
① 실제 탄소
함량(wt.%)
②Actual carbon
Content (wt.%)
② ②-①②-① 브리넬경도
(HB)Brinell hardness
(HB) 제2상 조직2nd phase organization 비교예 1Comparative Example 1 AA 432432 100100 0.2000.200 0.0810.081 -0.119-0.119 395395 F8%,B11%F8%, B11% 비교예 2Comparative Example 2 BB 401401 5050 0.1780.178 0.1210.121 -0.057-0.057 445445 F2%, B3%F2%, B3% 발명예 1Inventory 1 CC 381381 5050 0.1740.174 0.1950.195 0.0210.021 519519 B3%B3% 비교예 3Comparative Example 3 DD 433433 5050 0.2750.275 0.1520.152 -0.123-0.123 404404 F1%. B4%F1%. B4% 발명예 2Inventory 2 EE 387387 3535 0.2290.229 0.2420.242 0.0130.013 505505 F1%, B3%F1%, B3% 발명예 3Inventory 3 EE 379379 7070 0.2180.218 0.2420.242 0.0240.024 523523 100%M100% M 비교예 4Comparative Example 4 FF 425425 5050 0.2490.249 0.1480.148 -0.101-0.101 405405 B4%B4% 비교예 5Comparative Example 5 GG 434434 2020 0.2860.286 0.1480.148 -0.138-0.138 364364 F6%, B7%F6%, B7% 발명예 4Honorable 4 HH 380380 5050 0.2660.266 0.2970.297 0.0310.031 531531 B3%B3% 발명예 5Inventory 5 II 379379 3535 0.2020.202 0.2120.212 0.0100.010 511511 100%M100% M 비교예 6Comparative Example 6 JJ 411411 3535 0.2810.281 0.20.2 -0.081-0.081 437437 F2%, B2%F2%, B2% 발명예 6Inventory 6 KK 372372 100100 0.1900.190 0.2520.252 0.0620.062 551551 100%M100% M 비교예 7Comparative Example 7 LL 417417 3535 0.2790.279 0.1980.198 -0.081-0.081 440440 F2%, B2%F2%, B2% 비교예 8Comparative Example 8 MM 394394 2020 0.2130.213 0.1990.199 -0.014-0.014 491491 F1%, B3%F1%, B3% 비교예 9Comparative Example 9 NN 417417 7070 0.2720.272 0.20.2 -0.072-0.072 448448 B4%B4% 발명예 7Honorable 7 OO 377377 8080 0.2220.222 0.260.26 0.0380.038 527527 B3%B3% 발명예 8Honors 8 PP 386386 5050 0.2510.251 0.270.27 0.0190.019 510510 B2%B2% 발명예 9Proposition 9 QQ 396396 100100 0.2220.222 0.2320.232 0.0100.010 502502 B3%B3%

상기 표 2에 나타난 바와 같이, 본 발명에 따라 실제 탄소함량이 필요탄소 함량보다 많은 발명예 1 내지 9의 경우에는 브리넬 경도(HB) 값이 500 HB 이상임을 알 수 있다.
As shown in Table 2, according to the present invention, in the case of Examples 1 to 9 in which the actual carbon content is larger than the necessary carbon content, the Brinell hardness (HB) value is more than 500 HB.

한편, 실제 탄소함량이 필요탄소 함량보다 적은 비교예 1 내지 9의 경우에는 브리넬 경도 값이 500 HB 미만임을 알 수 있다.
On the other hand, in the case of Comparative Examples 1 to 9 in which the actual carbon content is smaller than the necessary carbon content, the Brinell hardness value is less than 500 HB.

본 발명을 앞서 기재한 바에 따라 설명하였지만, 다음에 기재하는 특허청구 범위의 개념과 범위를 벗어나지 않는 한, 다양한 수정 및 변형이 가능하다는 것을 본 발명이 속하는 기술 분야에 종사하는 자들은 쉽게 이해할 것이다.It will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the following claims.

Claims (6)

열간압연된 열연강판을 냉각하는 공정을 포함하여 제조되는 강판으로서,
중량%로, 탄소(C): 0.05 ~ 0.3wt%, 규소(Si): 0.5%이하(0%는 제외), 망간(Mn): 2.5% 이하(0%는 제외), 크롬(Cr): 1.5% 이하(0%는 제외), 몰리브덴(Mo): 1.0%이하(0%는 제외), 니켈(Ni): 1.0% 이하(0%는 제외), 니오비움(Nb): 0.1% 이하(0%는 제외), 타이타니움(Ti): 0.1% 이하(0%는 제외), 바나디움(V): 0.1% 이하(0%는 제외), 보론(B): 0.01% 이하(0%는 제외), 알루미늄(Al): 0.1% 이하(0%는 제외), 잔부 철(Fe) 및 기타 불가피한 불순물로 이루어지고;
상기 탄소(C)의 최소 함량은 하기 관계식(1)을 만족하고;
[관계식 1]
C(탄소(C)의 최소 함량)≥ 0.481-0.104Mn-0.035Si-0.088Cr-0.054Ni-0.035Mo-0.0003C.R.
[여기서, Mn, Si, Cr, Ni 및 Mo은 각 원소들의 함유량을 중량%로 나타낸 값이고, C.R.은 열연강판의 냉각 시 냉각속도를 나타낸 값이고, 단위는 ℃/sec임]
95vol.% 이상의 마르텐사이트 상을 포함하는 미세조직을 갖고; 그리고
500HB이상의 브리넬 경도를 갖는 고 경도 강판.
A steel sheet produced by including a step of cooling a hot-rolled steel sheet subjected to hot rolling,
(C): 0.05 to 0.3% by weight, Si: 0.5% or less (excluding 0%), manganese (Mn): not more than 2.5% Not more than 1.5% (excluding 0%), molybdenum (Mo): not more than 1.0% (excluding 0%), nickel (Ni): not more than 1.0% (excluding 0%) and niobium (Excluding 0%), titanium (Ti): not more than 0.1% (excluding 0%), vanadium (V): not more than 0.1% (Al): not more than 0.1% (excluding 0%), the balance iron (Fe) and other unavoidable impurities;
The minimum content of carbon (C) satisfies the following relational expression (1);
[Relation 1]
C (minimum content of carbon (C))? 0.481-0.104Mn-0.035Si-0.088Cr-0.054Ni-0.035Mo-0.0003CR
Wherein the content of Mn, Si, Cr, Ni and Mo is expressed in weight%, CR is a value indicating the cooling rate during cooling of the hot-rolled steel sheet, and the unit is ° C / sec.
At least 95 vol.% Of a martensite phase; And
High hardness steel sheet having Brinell hardness of 500HB or more.
제1항에 있어서, 상기 미세조직은 마르텐사이트 이외의 제2상 조직으로 5.0vol.% 미만의 페라이트 및 베이나이트 중 1 종 또는 2종을 포함하는 것을 특징으로 하는 고 경도 강판.
The high hardness steel sheet according to claim 1, wherein the microstructure comprises a second phase structure other than martensite and contains at least one of ferrite and bainite of less than 5.0 vol%.
제1항에 있어서,
상기 관계식(1)은 하기 관계식(3)으로부터 도출된 것임을 특징으로 하는 고 경도 강판.
[관계식 3]
HB (브리넬 경도) = 100.4 + 830.5*C + 86.5*Mn + 28.8*Si + 73.4*Cr +
44.5*Ni + 28.8*Mo + 0.252*C.R.
[여기서, C, Mn, Si, Cr, Ni 및 Mo은 각 원소들의 함유량을 중량%로 나타낸 값이고, C.R.은 열연강판의 냉각 시 냉각속도를 나타낸 값이고, 단위는 ℃/sec임]
The method according to claim 1,
Wherein the relational expression (1) is derived from the following relational expression (3).
[Relation 3]
HB = Brinell Hardness = 100.4 + 830.5 * C + 86.5 * Mn + 28.8 * Si + 73.4 * Cr +
44.5 * Ni + 28.8 * Mo + 0.252 * CR
Wherein CR, Mn, Si, Cr, Ni and Mo are values indicating the content of each element in weight%, CR is a value indicating cooling rate during cooling of the hot-rolled steel sheet,
중량%로, 탄소(C): 0.05 ~ 0.3wt%, 규소(Si): 0.5%이하(0%는 제외), 망간(Mn): 2.5% 이하(0%는 제외), 크롬(Cr): 1.5% 이하(0%는 제외), 몰리브덴(Mo): 1.0% 이하(0%는 제외), 니켈(Ni): 1.0%이하(0%는 제외), 니오비움(Nb): 0.1% 이하(0%는 제외), 타이타니움(Ti): 0.1% 이하(0%는 제외), 바나디움(V): 0.1% 이하(0%는 제외), 보론(B): 0.01% 이하(0%는 제외), 알루미늄(Al): 0.1% 이하(0%는 제외), 잔부 철(Fe) 및 기타 불가피한 불순물로 이루어지는 강 슬라브를 열연강판으로 열간압연한 후, 냉각시켜 95vol.% 이상의 마르텐사이트 상을 포함하는 미세조직 및 500HB이상의 브리넬 경도를 갖는 강판을 제조하는 방법으로서, 상기 탄소(C)의 최소 함량은 하기 관계식(1)을 만족하는 고 경도 강판의 제조방법.
[관계식 1]
C(탄소(C)의 최소 함량)≥ 0.481-0.104Mn-0.035Si-0.088Cr-0.054Ni-0.035Mo-0.0003C.R.
[여기서, Mn, Si, Cr, Ni 및 Mo은 각 원소들의 함유량을 중량%로 나타낸 값이고, C.R.은 열연강판의 냉각 시 냉각속도를 나타낸 값이고, 단위는 ℃/sec임]
(C): 0.05 to 0.3% by weight, Si: 0.5% or less (excluding 0%), manganese (Mn): not more than 2.5% Not more than 1.5% (excluding 0%), molybdenum (Mo): not more than 1.0% (excluding 0%), nickel (Ni): not more than 1.0% (excluding 0%) and niobium (Excluding 0%), titanium (Ti): not more than 0.1% (excluding 0%), vanadium (V): not more than 0.1% Steel slabs composed of iron (Fe) and other unavoidable impurities are hot-rolled into hot-rolled steel sheets, and then cooled to obtain 95 vol% or more of martensite phase And a Brinell hardness of 500 HB or more, wherein the minimum content of carbon (C) satisfies the following relational expression (1): " (1) "
[Relation 1]
C (minimum content of carbon (C))? 0.481-0.104Mn-0.035Si-0.088Cr-0.054Ni-0.035Mo-0.0003CR
Wherein the content of Mn, Si, Cr, Ni and Mo is expressed in weight%, CR is a value indicating the cooling rate during cooling of the hot-rolled steel sheet, and the unit is ° C / sec.
제4항에 있어서, 상기 열연강판의 냉각 시 냉각속도는 20~150℃/sec 인 것을 특징으로 하는 고 경도 강판의 제조방법.
The method of manufacturing a high-hardness steel plate according to claim 4, wherein the cooling rate of the hot-rolled steel sheet during cooling is 20 to 150 ° C / sec.
제4항 또는 제5항에 있어서, 상기 열연강판의 냉각 시 냉각 종료온도는 Ms 점(마르텐사이트 변태 시작온도) 이하인 것을 특징으로 하는 고 경도 강판의 제조방법.The method for producing a high hardness steel sheet according to claim 4 or 5, wherein the cooling end temperature during cooling of the hot-rolled steel sheet is equal to or lower than the Ms point (martensitic transformation start temperature).
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WO2017034216A1 (en) 2017-03-02

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