KR20030083276A - Bake-hardening high tension steel sheet and method for manufacturing the same - Google Patents

Bake-hardening high tension steel sheet and method for manufacturing the same Download PDF

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KR20030083276A
KR20030083276A KR1020020021741A KR20020021741A KR20030083276A KR 20030083276 A KR20030083276 A KR 20030083276A KR 1020020021741 A KR1020020021741 A KR 1020020021741A KR 20020021741 A KR20020021741 A KR 20020021741A KR 20030083276 A KR20030083276 A KR 20030083276A
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steel sheet
weight
hardening
high strength
carbon
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KR1020020021741A
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Korean (ko)
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윤치상
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현대자동차주식회사
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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
    • 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
    • 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
    • C22C38/004—Very low carbon steels, i.e. having a carbon content of less than 0,01%
    • 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
    • C22C38/14—Ferrous alloys, e.g. steel alloys containing titanium or zirconium

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Heat Treatment Of Sheet Steel (AREA)

Abstract

PURPOSE: Provided is a bake hardening high strength steel sheet in which contents of manganese and phosphorus are increased to improve tensile strength compared to conventional high strength steel sheets, and in which boron is added and contents of carbon, aluminum and titanium are controlled to remove secondary processing brittleness. CONSTITUTION: The bake hardening high strength steel sheet is consisted of an alloy composition comprising 0.0015 to 0.0040 wt.% of carbon (C), 1.0 to 1.8 wt.% of manganese (Mn), 0.06 to 0.12 wt.% of phosphorus (P), 0.0005 to 0.0015 wt.% of boron (B), 0.01 to 0.02 wt.% of titanium (Ti), and 0.03 to 0.06 wt.% of aluminum (Al). The manufacturing method of bake hardening high strength steel sheet comprises the processes of melting the alloy composition in converter under the ordinary operation conditions; continuously casting the molten steel; reheating the continuously cast steel at a temperature of 1,200 deg.C or more for one hour so that austenite texture is formed by performing annealing; performing hot rolling an annealed steel at a temperature of Ar3 or more; pickling the hot rolled steel to remove oxide film on the surface of the steel sheet; cold rolling the pickled steel sheet at a reduction ratio of 75 to 80%; continuously annealing the cold rolled steel sheet at a temperature of 800 to 850 deg.C; and temper rolling the continuous annealed steel sheet at a reduction ratio of 0.7 to 1.5%.

Description

소부경화형 고장력강판 및 이것의 제조방법{Bake-hardening high tension steel sheet and method for manufacturing the same}Bake-hardening high tension steel sheet and method for manufacturing the same

본 발명은 소부경화형 고장력강판 및 이것의 제조방법에 관한 것으로서, 더욱 상세하게는 종래의 고장력강판의 경우보다 강도를 높이기 위해 망간과 인의 함량을 높이고, 2차 가공취성을 없애기 위해 보론을 첨가했을 뿐만 아니라, 탄소, 알루미늄 및 티타늄의 함량을 조절한 소부경화형 고장력강판 및 이것의 제조방법에 관한 것이다.The present invention relates to a small hardening type high tensile strength steel sheet and a method of manufacturing the same, and more specifically, to increase the strength of manganese and phosphorus in order to increase the strength of the conventional high tensile strength steel sheet, boron was added to remove secondary processing brittleness. Rather, the present invention relates to a hardening type high tensile strength steel sheet having a controlled content of carbon, aluminum and titanium, and a method of manufacturing the same.

소부경화형이란 자동차의 차체 제조공정에서 강판을 원하는 형상으로 성형 한 후, 도장을 하고 이것의 건조를 위해 소정의 온도와 시간으로 소부처리를 하게되는데, 이 과정에서 강판이 경화되는 성질을 의미한다.The hardening hardening type means that the steel sheet is molded into a desired shape in a vehicle body manufacturing process of an automobile, and then coated and calcined at a predetermined temperature and time for drying thereof. This means that the steel sheet is hardened in this process.

소부경화형 강판은 연질의 상태에서 원하는 모양으로 성형이 되고, 성형후에 강도가 증가되기 때문에, 강도가 증가함에 따라 성형성이 악화되는 종래의 고강도 냉연강판에 비해 이상적인 강화방법으로 기대를 받고 있으며, 우수한 성형성과 내 덴트(dent)성이 요구되는 자동차의 외판용으로 주로 사용되고 있다.Since the hardened hardened steel sheet is molded into a desired shape in a soft state and its strength is increased after molding, it is expected to be an ideal reinforcing method as compared with the conventional high strength cold rolled steel sheet, which is deteriorated with increasing strength. It is mainly used for exterior panels of automobiles that require moldability and dent resistance.

최근에는 자동차의 연비향상을 위한 경량화 및 환경문제등에 대한 적극적인 대응의 일환으로 적용되는 강판에 대한 두께의 감소가 요구된다. 그러나 자동차 외판재에 적용되는 강판의 두께 감소는 내덴트성(강판 외부압력에 대한 저항성 지수를 나타내는 것으로 그 지수가 높을 수록 양호)의 감소를 수반함으로 자동차에 적용되는 강판의 두께를 감소시키는 것은 한계가 있다.In recent years, the reduction of the thickness of the steel sheet applied as part of an active response to weight reduction and environmental problems for improving the fuel economy of the automobile is required. However, the decrease in the thickness of the steel sheet applied to the automobile exterior member material is accompanied by a decrease in the dent resistance (the index of resistance to the external pressure of the steel sheet, the higher the index is good), it is limited to reduce the thickness of the steel sheet applied to the automobile There is.

이러한 특성을 감안하여 보다 효율적인 소부경화형 강판의 제조 방법이 여러각도로 개발되고 있다.In view of these characteristics, a more efficient method for producing a hardened hardened steel sheet has been developed at various angles.

기존의 소부경화형 강판의 제조 방법은 인장강도가 35㎏f/㎟ 정도의 강판을 제조하는 것을 목적으로 하는 소부경화성 및 성형성이 우수한 냉간압연강판 제조 방법(국내특허공고번호:제96-5238호), 또한 성형성이 우수한 소부경화형 고강도 냉연강판 제조법(국내특허출원번호:2000-045984), 소부경화성이 우월한 냉연강철판(국내특허출원번호:2000-702098), 고성형성 소부경화형 고강도 냉연강판 및 그 제조법(국내특허공개번호:2001-004488), 성형성이 우수한 고강도냉연강판의 제조법(국내출원번호:1998-053898), 성형성과 소부경화성이 우수한 연질냉연강판 제조방법(국내특허출원번호: 1998-035266), 성형성이 우수한 소부경화형 저탄소 냉연강판의 제조방법 (국내특허출원번호: 1997-055661), 성형성과 소부경화성이 우수한 유기피복형 냉연강판의 제조방법(국내특허출원번호: 1995-068473), 성형성 및 소부경화성이 우수한 상소둔형 냉연강판 및 그 제조방법(국내특허출원번호: 1995-009670), 우수한 성형성과 소부경화성을 가진 냉연강판 제조방법(국내특허출원번호: 1994-035833) 등의 많은 제조방법이 알려져 있다.The conventional method for producing a hardened hardened steel sheet is a method of manufacturing cold rolled steel sheet having excellent hardened hardenability and moldability for the purpose of manufacturing a steel sheet having a tensile strength of about 35 kgf / mm 2 (Domestic Patent Publication No. 96-5238). ), And also the method of producing hardened hardened high strength cold rolled steel sheet (Domestic Patent Application No. 2000-045984), cold rolled steel sheet having excellent hardened hardenability (Domestic Patent Application No. 2000-702098), high moldability hardened cold rolled high strength cold rolled steel sheet and its Manufacturing method (Domestic Patent Publication No. 2001-004488), Manufacturing method of high strength cold rolled steel sheet with excellent formability (Domestic Application No .: 1998-053898), Manufacturing method of soft cold rolled steel sheet having excellent moldability and hardening hardening (Domestic Patent Application No .: 1998- 035266), method for producing small hardened low carbon cold rolled steel sheet with excellent formability (domestic patent application number: 1997-055661), method for manufacturing organic coated cold rolled steel sheet with excellent moldability and hardenability (national patent application number No. 1995-068473), an annealing cold rolled steel sheet having excellent formability and hardening hardening, and a method of manufacturing the same (domestic patent application No. 1995-009670), a method for manufacturing a cold rolled steel sheet having excellent moldability and hardening hardening (domestic patent application: Many production methods are known, such as 1994-035833).

그러나, 위에서 개발한 강판은 인장강도가 28-35kgf/㎟급이 주종이며 강도가 가장 높은 것이 40kgf/㎟급으로 강도가 낮아 소부경화가 되더라도 내덴트 특성에 한계가 있고, 경량화를 조금밖에 이룰 수 없는 단점이 있다.However, the steel plate developed above is mainly used for 28-35kgf / mm2 class, and the highest strength is 40kgf / mm2 class. There are no drawbacks.

따라서, 자동차용 외판의 내덴트성을 향상시키고, 경량화를 증대시키기 위해서는 새로운 고장력강판의 제조 방법에 대한 개발의 필요성이 지금까지도 절실히 대두되고 있다.Accordingly, in order to improve the dent resistance of automobile outer panels and increase the weight reduction, the necessity of developing a new high-strength steel sheet manufacturing method has been urgently developed.

이에, 본 발명은 상기와 같은 점을 감안하여 연구 개발한 결과, 강판내의 망간과 인의 함량을 증가시키고, 보론을 첨가시킨 소부경화형 고장력 강판의 합금 조성과, 이 합금 조성을 이용하여 통상의 열연 및 냉연을 행한 후 소둔조질압연을 실시함으로써, 성형성 및 소부경화 특성이 우수하고, 내덴트성을 향상시킬 수 있으며, 차체 외판 적용시 경량화를 실현할 수 있도록 한 소부경화형 고장력강판 및 이것의 제조방법을 제공하는데 그 목적이 있다.Accordingly, the present invention has been developed in view of the above, as a result of the increase in the content of manganese and phosphorous in the steel sheet, and the boron-added hardening type high tensile strength steel sheet and the alloy composition using this alloy composition, using the conventional hot rolled and cold rolled After performing the annealing and temper rolling, the present invention provides a small hardening type high tensile strength steel sheet and a method of manufacturing the same, which are excellent in formability and hardening hardening characteristics, can improve dent resistance, and can realize weight reduction in the application of outer shell plates. Its purpose is to.

이러한 목적을 달성하기 위한 본 발명은:The present invention for achieving this object is:

상기와 같은 목적을 달성하기 위한 본 발명은 탄소(C):0.0015 내지 0.0040 중량%, 망간(Mn):1.0 내지 1.8 중량%, 인(P):0.06 내지 0.12 중량%, 티타늄(Ti): 0.01 내지 0.02 중량%, 보론: 0.0005내지 0.0015 중량%, 알루미늄(Al): 0.03 내지 0.06 중량%, 잔부 철(Fe) 및 기타 불가피한 불순물로 이루어진 고강도 소부경화형 고장력강판과; 이렇게 조성된 합금 성분계를 통상의 조업조건으로 전로에서 용해시키고, 연속주조한 후, 1200℃이상에서 1시간 동안 재가열하여 균질화처리 실시로 오스테나이트 조직을 만들고, Ar3이상의 온도에서 열간압연을 실시하며, 표면 산화피막을 제거하기 위해 산세처리 후 75∼80%의 압하율로 냉간압연을 행한 다음, 800∼850℃에서 연속소둔을 실시하고, 0.7∼1.5%의 압하율로 조질압연을 시행하는 것을 특징으로 하는 소부경화형 고장력강판의 제조 방법을 제공한다.The present invention for achieving the above object is carbon (C): 0.0015 to 0.0040% by weight, manganese (Mn): 1.0 to 1.8% by weight, phosphorus (P): 0.06 to 0.12% by weight, titanium (Ti): 0.01 To 0.02% by weight, boron: 0.0005 to 0.0015% by weight, aluminum (Al): 0.03 to 0.06% by weight, high strength bake hardened high tensile steel sheet composed of residual iron (Fe) and other unavoidable impurities; The alloy component system thus prepared is dissolved in a converter under normal operating conditions, continuously cast, and reheated for 1 hour at 1200 ° C. or higher to make an austenite structure by performing homogenization treatment, and hot rolling at a temperature of Ar 3 or higher. After the pickling treatment to remove the surface oxide film, cold rolling was carried out at a reduction ratio of 75 to 80%, followed by continuous annealing at 800 to 850 ° C, and temper rolling at a reduction ratio of 0.7 to 1.5%. Provided is a method for producing a hardened hardened steel sheet.

이하, 본 발명의 고강도 소부경화형 고장력강판 조성 및 이것의 제조방법에 대하여 보다 구체적으로 살펴보면 다음과 같다.Hereinafter, the high-strength hardened high tensile steel sheet composition of the present invention and a manufacturing method thereof will be described in more detail.

우선, 본 발명의 고강도 소부경화형 고장력강판은 탄소(C) 0.0015 내지 0.0040 중량%, 망간(Mn) 1.0 내지 1.8 중량%, 인(P) 0.06 내지 0.12 중량%, 보론 0.0005내지 0.0015중량%, 티타늄(Ti) 0.01 내지 0.02 중량% 및 알루미늄(Al) 0.03 내지 0.06 중량%으로 이루어진 것에 특징이 있다.First, the high-strength hardened high tensile steel sheet of the present invention is 0.0015 to 0.0040% by weight of carbon (C), 1.0 to 1.8% by weight of manganese (Mn), 0.06 to 0.12% by weight of phosphorus (P), boron 0.0005 to 0.0015% by weight, titanium ( Ti) 0.01 to 0.02 wt% and aluminum (Al) 0.03 to 0.06 wt%.

이러한 강판의 합금 조성에서, 탄소(C)는 소부경화효과를 부여하기 위해 첨가되는 것으로서, 강판 내부에 10ppm 정도의 양이 고용되어 포함하는 것이 바람직하다.In the alloy composition of such a steel sheet, carbon (C) is added in order to give a baking hardening effect, and it is preferable to contain the amount of about 10 ppm solid solution inside the steel sheet.

강중에 들어있는 탄소는 티타늄과 일부 결합하므로 이러한 양을 확보하기 위해 본 발명에서는 0.002 중량% 이상 존재하여야 하며, 탄소함량이 0.003 중량%를 초과하는 경우 상온에서 시효발생하여 스트레쳐 스트레인(Stretcher Strain)에 의한 외관불량의 원인이 되는 문제점이 발생하게 된다.Carbon contained in the steel is partially bonded with titanium, so in order to secure this amount, the present invention must be present in an amount of 0.002% by weight or more, and when the carbon content exceeds 0.003% by weight, the aging occurs at room temperature to cause the strainer strain. This causes a problem that causes the appearance defects.

또한, 강 중에 존재하는 황의 유해함을 방지하기 위해 첨가하는 망간(Mn)은 치환형 고용체로서, 강판의 강도를 증가시키는 효과가 있어서 강 중에 1.0 내지 1.8 중량%를 포함시키는데, 만일 1.8 중량%를 초과하여 포함하는 경우 성형성이 떨어지는 문제점이 있어 바람직하지 않다.In addition, manganese (Mn) added to prevent the harmfulness of sulfur present in the steel is a substitutional solid solution, and has an effect of increasing the strength of the steel sheet to include 1.0 to 1.8% by weight in the steel, if 1.8% by weight If it is included in excess, there is a problem that the moldability is poor, which is not preferable.

그리고, 상기 성분 중 인(P)은 강 중에 존재시 치환형 고용체를 만들어 강도를 향상시키는 효과가 있어 강 중에 0.06 내지 0.12 중량%를 첨가한다.Phosphorus (P) in the component is effective in improving the strength by making a substituted solid solution when present in the steel, so that 0.06 to 0.12% by weight is added to the steel.

그러나, 만일 인의 함량이 0.12 중량%를 초과하게 되면 성형성이 떨어지고 입계에 석출하여 연성취성 천이온도를 높여 충돌강도를 떨어뜨리므로 그 이하로 제한하는 것이 바람직하다.However, if the content of phosphorus exceeds 0.12% by weight, the moldability is inferior, it is preferable to limit to less than that because it precipitates at the grain boundary to increase the ductile brittle transition temperature to drop the impact strength.

그리고 제조공정상 인이 입계에 석출하면 입계의 결합력이 떨어져 2차가공취성을 일으킬 수 있으므로 입계의 결합력을 증대시키기 위해 보론을 0.0005%이상 첨가하며, 성형성 열화방지를 위해 0.0015% 이하로 제한한다.In addition, when phosphorus precipitates at grain boundaries in the manufacturing process, the binding force of grain boundaries may drop, causing secondary processing brittleness. Therefore, boron is added at 0.0005% or more to increase the bonding strength of grain boundaries, and is limited to 0.0015% or less to prevent moldability deterioration.

또한, 티타늄(Ti)은 본 발명에서 0.01 내지 0.02 중량%를 포함하는 것이 바람직하다.왜냐하면, 티타늄은 탄소, 황, 질소와 결합하는데, 본 발명에 따른 강판이 소부경화성을 갖으려면 강판내에 결합하지 않은 탄소, 즉 고용탄소가 0.001 중량% 존재하여야 하기 때문이다.In addition, the titanium (Ti) is preferably included in the present invention 0.01 to 0.02% by weight. Because titanium is bonded with carbon, sulfur, nitrogen, the steel sheet according to the present invention is not bonded in the steel sheet in order to have a hardening hardenability. Carbon, that is, dissolved carbon must be present in 0.001% by weight.

즉, 이러한 고용탄소가 강판부품의 도장후 전착오븐에서 베이킹(Baking)시에 전위 하단부로 이동하여 전위를 고착시켜 이동을 방해하여 부품의 항복강도를 높이게 되는데, 이러기 위해서는 티타늄과 결합하지 않는 탄소가 0.001 중량% 존재하는 것이 바람직하기 때문이다.That is, the solid solution carbon moves from the electrodeposition oven to the lower part of the dislocation at the time of baking in the electrodeposition oven after painting the steel sheet part, thereby fixing the dislocation and increasing the yield strength of the part. This is because it is preferably present in 0.001% by weight.

따라서, 티타늄의 양이 상기 범위를 초과하여 너무 과다하게 되면 탄소와 전부 결합하게 되어 고용탄소가 없어져 소부경화 효과가 없어지게 되고, 너무 소량이면 고용탄소가 너무 많아 상온시효의 우려가 있게 되어 바람직하지 않게 된다.Therefore, if the amount of titanium is too much in excess of the above range it is combined with all the carbon to eliminate the solid solution carbon is lost the hardening hardening effect, too small a too large amount of the solid solution carbon may cause the room temperature aging is not preferable Will not.

이밖에도, 알루미늄(Al)은 강 중에 들어있는 질소와 결합하여 상온시효방지를 위해 0.03 중량% 이상 첨가하는 것이 바람직하나, 0.06 중량% 초과하는 경우 성형성이 떨어지는 문제점이 있어 바람직하지 않다.In addition, aluminum (Al) is preferably added at least 0.03% by weight in order to prevent room temperature aging by combining with nitrogen contained in steel, but when it exceeds 0.06% by weight, there is a problem in inferior moldability.

따라서, 본 발명은 철을 주성분으로 이상의 성분을 첨가하는데, 이때 특히 소부경화효과를 극대화하고 상온시효를 방지하기 위하여 티타늄과 탄소의 양을 엄격히 관리하여야 한다.Therefore, in the present invention, iron is added to the above components as a main component, in particular, in order to maximize the hardening effect of baking and to prevent room temperature aging, the amount of titanium and carbon must be strictly managed.

여기서, 본 발명에 따른 소부경화형 고장력강판의 제조 방법에 대하여 설명하면 다음과 같다.Here, a description will be given of a method for producing a small hardening type high tensile strength steel sheet according to the present invention.

먼저, 상술한 바와 같이, 탄소(C) 0.0015 내지 0.0040 중량%, 망간(Mn) 1.0 내지 1.8 중량%, 인(P) 0.06 내지 0.12 중량%, 보론 0.0005내지 0.0015중량%, 티타늄(Ti) 0.01 내지 0.02 중량% 및 알루미늄(Al) 0.03 내지 0.06 중량%으로 이루어진 것을 특징으로 하는 본 발명의 합금계 성분을 전로에서 용해시키고 연속주조를 시행한다.First, as described above, carbon (C) 0.0015 to 0.0040% by weight, manganese (Mn) 1.0 to 1.8% by weight, phosphorus (P) 0.06 to 0.12% by weight, boron 0.0005 to 0.0015% by weight, titanium (Ti) 0.01 to The alloy-based component of the present invention, which comprises 0.02% by weight and 0.03% to 0.06% by weight of aluminum (Al), is dissolved in a converter and subjected to continuous casting.

다음, 1200℃이상에서 1시간 동안 재가열하여 균질화처리 실시로 오스테나이트 조직을 만들고, Ar3이상의 온도에서 열간압연을 실시한다.Next, re-heat for 1 hour at 1200 ° C or more to make austenite structure by the homogenization treatment, and hot rolling at a temperature of Ar3 or more.

이어서, 표면 산화피막을 제거하기 위해 산세처리 후 75∼80%의 압하율로 냉간압연을 행한다.Subsequently, cold rolling is performed at a reduction ratio of 75 to 80% after pickling to remove the surface oxide film.

마지막으로, 800∼850℃에서 연속소둔을 실시하고, 0.7∼1.5%의 압하율로 조질압연을 시행한다.Finally, continuous annealing is carried out at 800 to 850 ° C., and temper rolling is carried out at a reduction ratio of 0.7 to 1.5%.

여기서, 본 발명의 합금계 성분을 전로에서 용해시키고 연속주조를 시행한 후, 1200℃ 이상에서 재가열하는 것은 균일한 조직의 오스테나이트를 만들기 위해서이고, 그 이하에서는 혼립이 발생하여 재질이 열화되기 때문이다.Here, the alloy component of the present invention is dissolved in a converter and subjected to continuous casting, and then reheated at 1200 ° C. or higher in order to make the austenite of a uniform structure. to be.

또한, 상기 열간압연온도가 Ar3이하가 되면 성형성이 열화되어 그 이상에서 실시하며, 산세처리는 열간압연시 발생한 강판 표면의 산화철 피막을 제거하기 위해 통상 10%의 염산에서 실시한다.In addition, when the hot rolling temperature is less than or equal to Ar3, the moldability is deteriorated, and the pickling treatment is performed at a temperature higher than that. The pickling treatment is usually performed at 10% hydrochloric acid to remove the iron oxide film on the surface of the steel sheet.

또한, 강판의 딥드로잉성에 영향을 주는 소성이방성지수를 높이기 위해 냉간압하율을 75%이상으로 하고, 압하율이 너무 높으면 조직 미세화에 의해 항복강도 및 인장강도가 증가하는 대신 신율이 떨어지므로 80%이하로 제한한다.In addition, in order to increase the plastic anisotropy index that affects the deep drawing property of the steel sheet, the cold reduction ratio is 75% or more. If the reduction ratio is too high, the yield strength and tensile strength decrease due to the structure refinement, and thus the elongation is decreased. It limits to the following.

냉각압연시 파괴된 조직을 복원하기 위해 800℃∼850℃이상에서 소둔을 실시하며, 이때 850℃ 이상이 되면 입자의 크기가 조대하게 되어 프레스 성형후 오렌지필 등의 불량이 발생할 수 있기 때문에 온도범위를 조절한다.Annealing is carried out at 800 ℃ ~ 850 ℃ to recover the destroyed structure during cold rolling, and when the temperature is over 850 ℃, the particle size becomes coarse, which can cause defects such as orange peel after press molding. Adjust

강중에 존재하는 10ppm정도의 고용탄소는 상온에서도 시간의 경과에 따라 강판 내부에 존재하는 전위 하단부에 이동하여 고착하게 되면, 상온시효를 발생시켜 항복점 연신에 따른 스트레쳐 스트레인 마크를 나타낼 수 있으므로, 이를 방지하기 위해 강판 두께의 0.7% 이상 조질 압연을 실시한다.The solid solution of about 10ppm present in the steel moves to the lower end of the dislocation existing inside the steel sheet at time even at room temperature and adheres to the lower end of the dislocation. In order to prevent the roughing, at least 0.7% of the thickness of the steel sheet is applied.

그에따라, 강판 내부에 모빌 디스로케이션(Mobile dislocation)을 증가시켜 상온시효을 방지할 수 있고, 1.5%이상이 되면 강판의 강도증가 및 성형성 하락을가져오므로 바람직하지 않다.Accordingly, by increasing the mobile dislocation (mobile dislocation) inside the steel sheet to prevent the room temperature aging, when more than 1.5% is not preferable because the strength of the steel sheet and the decrease in formability.

이하, 본 발명을 실시예에 의하여 더욱 상세히 설명하고자 한다.Hereinafter, the present invention will be described in more detail with reference to Examples.

하기의 실시예는 오로지 본 발명을 보다 구체적으로 설명하기 위한 것으로, 이들 실시예에 의하여 본 발명의 범위가 한정되지 않는다는 것은 본 발명이 속하는 기술분야에서 통상의 지식을 가진 자에게 있어서 자명할 것이다.The following examples are only for illustrating the present invention in more detail, it will be apparent to those skilled in the art that the scope of the present invention is not limited by these examples.

본 발명에 따른 소부경화형 고장력강판의 합금 조성 및 그 함량을 통상의 방법으로 용강을 제조한 후, 이를 전로에서 용해시키고 연속주조한 후, 상기와 같은 조건으로 열간압연 및 냉간압연, 소둔조질압연을 실시하여 제조한 강판에 대하여 항복강도, 인장강도, 신율 및 소부경화량을 측정하였으며 그 결과를 다음 표 1에 요약하여 나타내었다.After the molten steel is manufactured in a conventional manner in the alloy composition and its content of the hardened hardened high tensile strength steel sheet according to the present invention, the molten steel is melted in a converter and continuously cast, followed by hot rolling, cold rolling, and annealing rolling. Yield strength, tensile strength, elongation, and calcination of the steel sheets produced were measured and the results are summarized in Table 1 below.

상기 시험방법은 본 발명의 방법으로 제조된 강판을 우선 KS5호의 인장시험편을 만든 후, 25톤 즈빅인장시험기를 사용하여 20㎜/분의 속도로 인장시험하여 항복강도, 인장강도, 신율을 측정하였으며, 소부경화량은 KS5호 인장시험편을 2% 인장한 후 170℃에서 20분동안 베이킹(Baking)한 후 항복강도를 측정하여 소부경화량을 산출하였다In the test method, the steel sheet prepared by the method of the present invention was first made a tensile test piece of KS5, and then subjected to a tensile test at a rate of 20 mm / min using a 25 ton ZIG tensile tester to measure yield strength, tensile strength, and elongation. , The cure hardening amount was calculated by measuring the yield strength after baking KS5 tensile test specimen for 2% and baking it at 170 ° C for 20 minutes.

이상의 결과로부터, 본 발명의 조성에 따른 강판은 항복강도 및 인장강도가 30%이상 향상되었음을 알 수 있으며, 소부경화량도 월등히 개선되었음을 알 수 있었다.From the above results, it can be seen that the steel sheet according to the composition of the present invention has improved yield strength and tensile strength by 30% or more, and the amount of hardening of the bake has been greatly improved.

이상에서 본 바와 같이, 본 발명에 다른 소부경화형 고장력강판 및 이것의 제조방법에 의하면, 강판내의 망간과 인의 함량을 증가시키고, 보론을 첨가시킨 소부경화형 고장력 강판의 합금 조성과, 이 합금 조성을 이용하여 통상의 열연 및 냉연을 행한 후 소둔조질압연을 실시함으로써, 성형성 및 소부경화 특성이 우수하고, 내덴트성을 향상시킬 수 있으며, 차체 외판 적용시 10%정도의 경량화를 실현하는 동시에 원가를 절감할 수 있는 장점을 제공한다.As described above, according to the present invention, the sheet hardening type high tensile strength steel sheet according to the present invention and a method of manufacturing the same are used to increase the content of manganese and phosphorus in the steel sheet and to use the alloy composition of the sheet hardening type high tensile strength steel sheet containing boron, and the alloy composition. By performing annealing and temper rolling after performing ordinary hot and cold rolling, it is excellent in formability and hardening hardening characteristics, and can improve dent resistance. It offers the benefits of doing so.

Claims (2)

소부경화형 고장력강판에 있어서,In the hardened high tensile steel sheet, 탄소(C) 0.0015 내지 0.0040 중량%, 망간(Mn) 1.0 내지 1.8 중량%, 인(P) 0.06 내지 0.12 중량%, 보론 0.0005내지 0.0015중량%, 티타늄(Ti) 0.01 내지 0.02 중량% 및 알루미늄(Al) 0.03 내지 0.06 중량%으로 이루어진 것을 특징으로 하는 소부경화형 고장력강판.0.0015 to 0.0040% by weight of carbon (C), 1.0 to 1.8% by weight of manganese (Mn), 0.06 to 0.12% by weight of phosphorus (P), 0.0005 to 0.0015% by weight of boron, 0.01 to 0.02% by weight of titanium (Ti) and aluminum (Al) ) Hardening hardening high strength steel sheet, characterized in that consisting of 0.03 to 0.06% by weight. 소부경화형 고장력강판의 제조 방법에 있어서,In the method of producing a hardened hardened high tensile steel sheet, 청구항 제1항의 합금계 성분을 통상의 조업조건으로 전로에서 용해시키고, 연속주조한 후, 1200℃이상에서 1시간 동안 재가열하여 균질화처리 실시로 오스테나이트 조직을 만들고, Ar3이상의 온도에서 열간압연을 실시하며, 표면 산화피막을 제거하기 위해 산세처리 후 75∼80%의 압하율로 냉간압연을 행한 다음, 800∼850℃에서 연속소둔을 실시하고, 0.7∼1.5%의 압하율로 조질압연을 시행하는 것을 특징으로 하는 소부경화형 고장력강판의 제조 방법.After dissolving the alloy component of claim 1 in a converter under normal operating conditions, continuous casting, and reheating for 1 hour at 1200 ° C. or higher to form an austenite structure by performing homogenization treatment, and performing hot rolling at a temperature of Ar 3 or higher. After pickling, cold rolling is carried out at a reduction ratio of 75 to 80% to remove the surface oxide film, followed by continuous annealing at 800 to 850 ° C, and temper rolling at a reduction ratio of 0.7 to 1.5%. Method for producing a small hardening type high tensile strength steel sheet, characterized in that.
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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS63247338A (en) * 1987-04-01 1988-10-14 Kawasaki Steel Corp High tensile strength steel plate for deep drawing having excellent secondary workability and baking hardenability
JPH06322441A (en) * 1993-05-11 1994-11-22 Sumitomo Metal Ind Ltd Production of high strength steel plate having baking hardenability
KR0121737B1 (en) * 1992-08-31 1997-12-04 다나까 미노루 Cold rolled sheet and hot-galvanized, cold-rolled sheet, both excellent in bake hardening, cold nonaging and forming
KR20000043767A (en) * 1998-12-29 2000-07-15 이구택 Cold-rolled steel strip of super high molding and high strength bh type and method of manufacturing the same
KR20010004488A (en) * 1999-06-29 2001-01-15 이구택 Bake hardening cold rolled steel with good formability and high strength and method of manufacturing the same

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS63247338A (en) * 1987-04-01 1988-10-14 Kawasaki Steel Corp High tensile strength steel plate for deep drawing having excellent secondary workability and baking hardenability
KR0121737B1 (en) * 1992-08-31 1997-12-04 다나까 미노루 Cold rolled sheet and hot-galvanized, cold-rolled sheet, both excellent in bake hardening, cold nonaging and forming
JPH06322441A (en) * 1993-05-11 1994-11-22 Sumitomo Metal Ind Ltd Production of high strength steel plate having baking hardenability
KR20000043767A (en) * 1998-12-29 2000-07-15 이구택 Cold-rolled steel strip of super high molding and high strength bh type and method of manufacturing the same
KR20010004488A (en) * 1999-06-29 2001-01-15 이구택 Bake hardening cold rolled steel with good formability and high strength and method of manufacturing the same

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