KR20020040213A - A METHOD FOR MANUFACTURING HOT ROLLED STEEL SHEET OF TENSILE STRENGTH 80kg/㎟ GRADE WITH EXCELLENT WEATHER RESISTANCE AND WORKABILITY - Google Patents

A METHOD FOR MANUFACTURING HOT ROLLED STEEL SHEET OF TENSILE STRENGTH 80kg/㎟ GRADE WITH EXCELLENT WEATHER RESISTANCE AND WORKABILITY Download PDF

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KR20020040213A
KR20020040213A KR1020000070188A KR20000070188A KR20020040213A KR 20020040213 A KR20020040213 A KR 20020040213A KR 1020000070188 A KR1020000070188 A KR 1020000070188A KR 20000070188 A KR20000070188 A KR 20000070188A KR 20020040213 A KR20020040213 A KR 20020040213A
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steel
workability
weather resistance
steel sheet
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노광섭
양부영
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이구택
주식회사 포스코
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B3/00—Rolling materials of special alloys so far as the composition of the alloy requires or permits special rolling methods or sequences ; Rolling of aluminium, copper, zinc or other non-ferrous metals
    • B21B3/02—Rolling special iron alloys, e.g. stainless steel
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B1/00—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations
    • B21B1/22—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling plates, strips, bands or sheets of indefinite length
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B37/00—Control devices or methods specially adapted for metal-rolling mills or the work produced thereby
    • B21B37/74—Temperature control, e.g. by cooling or heating the rolls or the product
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B1/00—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations
    • B21B1/22—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling plates, strips, bands or sheets of indefinite length
    • B21B2001/225—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling plates, strips, bands or sheets of indefinite length by hot-rolling
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B15/00—Arrangements for performing additional metal-working operations specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills
    • B21B2015/0057—Coiling the rolled product
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B2261/00—Product parameters
    • B21B2261/20—Temperature

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Heat Treatment Of Steel (AREA)

Abstract

PURPOSE: Provided is a hot rolled steel sheet of tensile strength 80kg/mm¬2 grade with excellent weather resistance and workability, which is appropriate for use in vehicle container. CONSTITUTION: The method includes the steps of: (i) reheating a steel slab comprising C 0.02-0.12wt.%, Si 0.7wt.% or less, Mn 0.5-2.0wt.%, P 0.05wt.% or less, S 0.01wt.% or less, Al 0.01-0.07wt.%, Nb 0.09wt.% or less, Ti 0.05wt.% or less, Ni 0.1-0.5wt.%, Cu 0.1-0.5wt.%, Cr 0.5-1.5wt.%, Ca .001-0.005wt.%, balance Fe, and other inevitable impurities in the temperature range of 1100 to 1300°C; (ii) finish hot rolling in the temperature range of 900 to 800°C; (iii) quenching at cooling rate of higher than 2 0°C/sec; (iv) coiling in the temperature range of 450 to 550°C. Optionally, vanadium is added in an amount of 0.01 to 0.07wt.%.

Description

인장강도 80㎏/㎟급 고가공성 고내후성 열연강판의 제조방법{A METHOD FOR MANUFACTURING HOT ROLLED STEEL SHEET OF TENSILE STRENGTH 80kg/㎟ GRADE WITH EXCELLENT WEATHER RESISTANCE AND WORKABILITY}FIELD OF MANUFACTURING METHOD FOR MANUFACTURING HOT ROLLED STEEL SHEET OF TENSILE STRENGTH 80kg / ㎜ GRADE WITH EXCELLENT WEATHER RESISTANCE AND WORKABILITY

본 발명은 건축, 해양구조물, 철도 차량 컨테이너 등에 사용되는 열연강판의 제조방법에 관한 것으로서, 보다 상세하게는 강 성분 및 제조조건을 조절함으로써 우수한 내후성과 함께 기계적 특성 및 가공성도 얻을 수 있는 인장강도 80kg/㎟급 고가공성 고내후성 열연강판의 제조방법에 관한 것이다.The present invention relates to a method for manufacturing hot rolled steel sheets used in construction, marine structures, railway vehicle containers, and the like, and more specifically, by adjusting steel components and manufacturing conditions, tensile strength of 80 kg, which can obtain mechanical properties and processability, together with excellent weather resistance The present invention relates to a method for manufacturing a high workability high weather resistance hot rolled steel sheet.

종래부터, 컨테이너 또는 철도차량 등의 경량화 및 장수명화를 목적으로 스테인레스 또는 알루미늄 등이 사용되어 왔다. 이와 같은 제품들에 요구되는 특성으로는, 굽힘성, 용접성 및 연신성 등이 있는데, 특히, 컨테이너 등은 해양 기후를 견디어 내야 하기 때문에 필수적으로 고내후성 강의 사용이 요구되었다. 일례로, 종래에는 고내후성 압연강재인 KS D3542(기호 SPA-H) 및 JIS G3125(기호 SPA-H)가 사용되어 왔으나, 이들 강은 인장강도가 50kg/㎟급으로 작아서 보다 큰 제품을 만드는 경우 자체의 중량으로 인한 제약이 있었다. 또한, 인장강도 60kg/㎟급의 용접구조용 열연강재가 있기는 하지만, 이는 용접성을 중시하여 목적으로 하는 내후성을 발휘하지는 못한다.Background Art Conventionally, stainless steel or aluminum has been used for the purpose of weight reduction and long life of containers or railway vehicles. Characteristics required for such products include bendability, weldability, and elongation. In particular, containers and the like have to withstand the marine climate, it is necessary to use a high weather resistance steel. For example, KS D3542 (symbol SPA-H) and JIS G3125 (symbol SPA-H), which are conventionally high weathering-rolled steels, have been used. There was a constraint due to its weight. In addition, although there are hot-rolled steel materials for welded structures having a tensile strength of 60 kg / mm 2, this does not exhibit the desired weather resistance with emphasis on weldability.

최근, 컨테이너의 자체 중량을 크게 감소시켜 보다 큰 컨테이너를 제작하고,이에 따라 수송의 효율성을 크게 증가시키기 위한 연구가 진행되고 있는데, 특히 내후성 및 고가공성을 갖는 열연강판의 제조방법에 관한 기술들이 제안되고 있다.일례로, 일본특개평7-207408호의 기술은, C:0.008% 이하, Si:0.5~2.5%, Mn:0.1~3.5%, P:0.03~0.20%, S:0.01% 이하, Cu:0.05~2.0%, Al:0.005~0.1% 및 N:0.008% 이하, Cr:0.05~6.0%, Ni:0.05~2.0% 및 Mo:0.05~3.0%, B:0.0003~0.002%를 함유한 강을 1100~1300℃로 가열하여 800~950℃의 온도 범위에서 압연종료하여 400~700℃의 온도 범위에서 권취하는 것을 특징으로 한다. 그러나, 이 기술은, 극히 일부의 인장강도만이 60~70kg/㎟급이고, 대부분이 50kg/㎟급의 강도를 발휘하며, 또한 주장하고 있는 화학성분에서 주요한 역할을 하는 탄소량의 범위가 0.008% 이하로 극히 낮기 때문에, 가공성은 향상되나 강도는 급격히 떨어지는 문제가 있다. 또한, 성분중 다량의 Cr, Mo, Ni, Cu 등이 첨가되어 있기 때문에, 특별한 제강 공정을 사용하여야 하는 등 제조비용의 경제성이 떨어진다.Recently, research has been conducted to greatly reduce the weight of the container to produce a larger container and to increase the efficiency of transportation. In particular, technologies related to a method of manufacturing a hot rolled steel sheet having weatherability and high workability are proposed. As an example, the technique of Japanese Patent Laid-Open No. 7-207408 is C: 0.008% or less, Si: 0.5-2.5%, Mn: 0.1-3.5%, P: 0.03-0.20%, S: 0.01% or less, Cu. Steel containing: 0.05 ~ 2.0%, Al: 0.005 ~ 0.1% and N: 0.008% or less, Cr: 0.05 ~ 6.0%, Ni: 0.05 ~ 2.0% and Mo: 0.05 ~ 3.0%, B: 0.0003 ~ 0.002% It is heated to 1100 ~ 1300 ℃ end of rolling in the temperature range of 800 ~ 950 ℃ characterized in that the winding in the temperature range of 400 ~ 700 ℃. However, in this technique, only a small part of tensile strength is 60 to 70 kg / mm2 class, most of which is 50 kg / mm2 class, and the amount of carbon that plays a major role in the claimed chemical composition is 0.008. Since it is extremely low at less than%, the workability is improved, but there is a problem that the strength drops sharply. In addition, since a large amount of Cr, Mo, Ni, Cu, and the like are added in the components, manufacturing costs are inferior, such as the use of a special steelmaking process.

또 다른 일례로, 일본특개평11-21622호는, C:0.15% 이하, Si:0.7% 이하, Mn:0.2~1.5%, P:0.03~0.15%, S:0.02% 이하, Cu:0.4% 이하, Al:0.01~0.1% 및 Cr:0.1% 이하, Ni:0.4~4.0% 및 Mo:0.1~1.5%를 함유한 강을 1050~1300℃로 가열하여 950℃ 이상의 온도에서 압하율 40% 이상의 열간압연을 하고 900~750℃의 온도 범위에서 압연종료하여 그후 공냉하는 기술을 제안하고 있다. 그러나, 이 경우에도 인장강도가 대부분 50kg/㎟급으로 극히 일부만이 60kg/㎟급의 인장특성을 발휘하기 때문에, 이 기술은 주로 인장강도 50kg/㎟급 내후성 열연강판에 적용하는 기술이라 할 수 있다. 또한, P을 0.03~0.15%로 다량 첨가하여 해수 분위기에서의 내식성을 향상하는 효과를 언급하고는 있으나, P의 다량 첨가는 중심편석 및 미소편석 등에 기인하여 강판의 가공성을 급격히 떨어뜨린다. 또한, Cr 함량이 낮기 때문에, 본 발명에서 주장하는 해수 분위기에서의 내식성이 떨어지는 단점이 있다. 한편, 제조방법에 있어서도 압연후 공냉방식을 적용하여, 본 발명과는 차이가 있다.As another example, Japanese Patent Application Laid-Open No. 11-21622, C: 0.15% or less, Si: 0.7% or less, Mn: 0.2 to 1.5%, P: 0.03 to 0.15%, S: 0.02% or less, Cu: 0.4% Below, the steel containing Al: 0.01 ~ 0.1% and Cr: 0.1% or less, Ni: 0.4 ~ 4.0% and Mo: 0.1 ~ 1.5% was heated to 1050-1300 ° C and the reduction ratio was 40% or more at a temperature of 950 ° C or higher. Hot rolling and finishing rolling in the temperature range of 900 ~ 750 ℃ and then air cooling technology has been proposed. However, even in this case, since most of the tensile strength is 50kg / mm2 and only a part of them exhibits tensile properties of 60kg / mm2, this technique is mainly applied to 50kg / mm2 weather resistant hot rolled steel sheet. . In addition, although the effect of improving the corrosion resistance in seawater atmosphere by adding a large amount of P at 0.03 to 0.15% is mentioned, the addition of a large amount of P sharply degrades the workability of the steel sheet due to the center segregation and micro segregation. In addition, since the Cr content is low, there is a disadvantage inferior corrosion resistance in the seawater atmosphere claimed in the present invention. On the other hand, the air-cooling method after rolling is also applied also to a manufacturing method, and there exists a difference with this invention.

또한, 일본특공평6-104858호는, C:0.02~0.12%, Si:0.5% 이하, Mn:0.1~2.0%, P:0.07~0.15%, S:0.02% 이하, Cu:0.25~0.55% 이하, Al:0.01~0.05% 및 Cr:0.3~1.25% , N:006% 이하, Ti:0.06~0.20%를 함유한 강을 12.1Xtieff(%)/Mn(%)>1.0 조건을 만족하도록 제어하고 1180℃ 이상의 온도로 재가열하여 880~950℃ 이상의 온도에서 열간압연을 하고 650℃의 온도 이하로 권취하는 기술을 제공하고 있다. 그러나, 이 기술의 경우도, 인장강도가 60kg/㎟급으로 본 발명 범위인 80kg/㎟급 보다 낮고, P이 0.07~0.15%로 다량 첨가되어 가공성이 열화한 단점이 있다. 또한, 이 기술은 Ti의 함량을 Mn 첨가량에 비례하여 첨가함에 의해, 유익한 효과를 발휘시키는 것을 특징으로 하기 때문에, 본 발명의 기술적 요지와는 차이가 있다.In addition, Japanese Patent Application Laid-Open No. 6-104858 is C: 0.02 to 0.12%, Si: 0.5% or less, Mn: 0.1 to 2.0%, P: 0.07 to 0.15%, S: 0.02% or less, Cu: 0.25 to 0.55% Steels containing Al: 0.01 ~ 0.05%, Cr: 0.3 ~ 1.25%, N: 006% or less, Ti: 0.06 ~ 0.20% are controlled to satisfy the conditions of 12.1Xtieff (%) / Mn (%)> 1.0 And reheating to a temperature of 1180 ℃ or more to provide a technique for hot rolling at a temperature of 880 ~ 950 ℃ or more and winding up to a temperature of 650 ℃ or less. However, this technique also has a disadvantage in that the tensile strength is 60 kg / mm2 class, lower than the 80kg / mm2 class of the present invention, and P is added in a large amount of 0.07 to 0.15%, thereby degrading workability. This technique differs from the technical gist of the present invention because it is characterized by exerting a beneficial effect by adding Ti content in proportion to the amount of Mn added.

이에, 본 발명자들은 상기와 같은 문제점을 해결하기 위하여 연구와 실험을 거듭하고 그 결과에 근거하여 본 발명을 제안하게 된 것으로, 본 발명은 강 성분중 Ca을 첨가하고 제조조건을 최적화함으로써, 고내후성, 고가공성 및 80kg/㎟급 인장강도의 열연강판을 제조하는 방법을 제공하는 것을 그 목적으로 한다.Accordingly, the present inventors have repeatedly conducted research and experiments to solve the above problems, and propose the present invention based on the results. The present invention provides high weather resistance by adding Ca in steel components and optimizing manufacturing conditions. To provide a method for producing a hot rolled steel sheet of high workability and 80kg / mm2 tensile strength.

상기 목적을 달성하기 위한 본 발명은, 중량%로, C:0.02~0.12%, Si:0.7% 이하, Mn:0.5~2.0%, P:0.05% 이하, S:0.01% 이하, Al:0.01~0.07%, Nb:0.09% 이하, Ti:0.05% 이하, Ni:0.1~0.5%, Cu:0.1~0.5%, Cr:0.5~1.5%, Ca:0.001~0.005%, 잔부 Fe 및 기타 불가피한 불순물이 함유되는 강을 1100~1300℃로 재가열하고 마무리 압연온도를 900~800℃ 범위로 하여 열간압연한 후, 20℃/sec 이상의 냉각속도로 냉각하고 450~550℃의 온도로 권취하는 인장강도 80kg/㎟급 고가공성 고내후성 열연강판의 제조방법에 관한 것이다.The present invention for achieving the above object, in weight%, C: 0.02 ~ 0.12%, Si: 0.7% or less, Mn: 0.5 ~ 2.0%, P: 0.05% or less, S: 0.01% or less, Al: 0.01 ~ 0.07%, Nb: 0.09% or less, Ti: 0.05% or less, Ni: 0.1-0.5%, Cu: 0.1-0.5%, Cr: 0.5-1.5%, Ca: 0.001-0.005%, balance Fe and other unavoidable impurities Reheat the contained steel to 1100 ~ 1300 ℃ and hot roll the finishing rolling temperature in the range of 900 ~ 800 ℃, and then cool it at a cooling rate of 20 ℃ / sec or higher and wind it at 450 ~ 550 ℃. The present invention relates to a method for manufacturing a mm2 high workability high weather resistance hot rolled steel sheet.

또한, 본 발명에서는 상기 강 성분 중 추가로 V이 0.01~0.07% 첨가될 수 있다.Also, in the present invention, V may be added in an amount of 0.01 to 0.07%.

이하, 본 발명에 대해 상세히 설명한다.Hereinafter, the present invention will be described in detail.

본 발명자들은, 다양한 가공특성, 즉 굽힘성, 용접성 및 연신성 등과 함께 내후성도 만족시켜 콘테이너 및 철도차량 등으로 유용한 고장력 강에 대해 연구 및 실험을 거듭하여 본 발명을 완성시킨 것으로, 본 발명의 강 성분은 다음과 같이 조성되는 것이 바람직하다.The present inventors have completed the present invention by repeating research and experiment on high tensile strength steel, which is useful for containers and railroad cars, satisfying weatherability along with various processing characteristics, that is, bendability, weldability and elongation, and the like. It is preferable that a component is comprised as follows.

먼저, 본 발명의 강 성분 중 C는, 강판의 강도향상을 위해 첨가되는 원소로서, 첨가량이 증가할수록 인장 및 항복강도는 증가되나, 과잉 첨가되면 소재의 가공성이 저하되므로, 그 상한을 0.12%로 설정하였다. 한편, C첨가량이 0.02% 이하이면 페라이트에 C가 모두 고용되고 함께 첨가되는 Nb, Ti, V 등과 반응해 석출되기 때문에, 석출강화 효과가 나타나지 않아, 소재의 강도증가효과를 얻지 못하는 문제가 있다. 따라서, 상기 C의 함량은 0.02~0.12%로 설정하는 것이 바람직하다.First, among the steel components of the present invention, C is an element added to improve the strength of the steel sheet, and the tensile strength and yield strength increase as the amount added increases, but the workability of the material decreases when excessively added, so the upper limit thereof is 0.12%. Set. On the other hand, if the amount of C added is 0.02% or less, all of the C is dissolved in the ferrite and precipitated by reacting with Nb, Ti, V, etc., which are added together, so that the precipitation strengthening effect does not appear, thereby increasing the strength of the material. Therefore, the content of C is preferably set to 0.02 to 0.12%.

Si은 용강탈산 및 고용강화효과를 제공할 뿐 아니라, 고온에서 강의 표층에 Fe와 함께 Fe2SiO4의 치밀한 산화물을 형성시켜 내식성을 향상시키는 역할도 한다. 따라서, Si은 내후성 향상을 위해서 첨가되어야 하지만, 과잉첨가되면 용접성이 저하하는 문제가 있으므로, 0.7% 이하로 첨가하는 것이 바람직하다.Si not only provides molten iron deoxidation and solid solution strengthening effect, but also forms a dense oxide of Fe 2 SiO 4 together with Fe in the surface layer of the steel at high temperature, thereby improving corrosion resistance. Therefore, although Si should be added for weather resistance improvement, since there exists a problem that weldability will fall when it adds excessively, it is preferable to add it at 0.7% or less.

Mn은 강을 고용강화시키는데 효과적인 원소로서, 강의 강도를 높이고 열간가공성을 향상시키는 중요한 원소이지만, MnS 형성에 의한 소재의 연성 및 가공성를 저해하는 원소이기도 하다. Mn의 함량이 적으면 가공성에는 유리하지만 강도에 문제가 있기 때문에, 0.5% 이상 첨가하는 것이 바람직하다. 또한, 과잉 첨가되는 경우 경제성 및 용접성이 나쁘기 때문에, 상한은 2.0%로 설정하는 것이 바람직하다.Mn is an effective element to solidify the steel, and is an important element for increasing the strength of steel and improving hot workability, but is also an element that inhibits the ductility and workability of the material due to MnS formation. If the content of Mn is small, it is advantageous for workability but there is a problem in strength, so it is preferable to add 0.5% or more. In addition, when excessively added, since economical efficiency and weldability are bad, it is preferable to set an upper limit to 2.0%.

P은 강의 내식성을 향상시키는 역할을 하기 때문에 내식성 측면에서는 다량 첨가되는 것이 바람직하지만, 주조시 중심편석을 가장 크게 일으키는 원소이기 때문에, 다량 첨가될 경우, 용접성 및 인성을 저하시키는 요인이 된다. 따라서, 그함량은 0.05% 이하로 제한하는 것이 바람직하다.Since P plays a role of improving the corrosion resistance of the steel, it is preferable to add a large amount in terms of corrosion resistance. However, since P is the element causing the largest segregation in casting, when P is added, it is a factor that reduces the weldability and toughness. Therefore, the content is preferably limited to 0.05% or less.

S은 내식성 향상에 효과가 있는 원소로 알려져 있지만, 강중 Mn과 결합해 부식 개시점 역할을 하는 비금속 개재물을 형성하므로, 가능한한 그 함량을 감소시키는 것이 바람직하다. 따라서, S 함량은 0.01% 이하로 첨가하는 것이 바람직하다.Although S is known as an element effective in improving corrosion resistance, it is preferable to reduce the content as much as possible, since it forms a non-metallic inclusion which serves as a starting point of corrosion by combining with Mn in steel. Therefore, the S content is preferably added at 0.01% or less.

Al은 일반적으로 용강탈산 및 내식성 향상에도 효과가 있는 원소이지만, 과잉 첨가되면 강중 개재물량을 증가시캬 강판의 가공성을 저하하기 때문에, 그 함량을 0.01~0.07%로 설정하는 것이 바람직하다.Al is generally an element which is effective in improving molten steel deoxidation and corrosion resistance, but when it is added excessively, the amount of inclusions in the steel increases and the workability of the steel sheet is lowered. Therefore, the content is preferably set at 0.01 to 0.07%.

Nb, Ti은 소재의 강도를 크게 증가시키는 역할을 하는 원소들로서, 그 첨가량은 통상의 고장력 저합금강에 적절한 범위인 0.09% 이하, 및 0.05% 이하로 제한하였다.Nb and Ti are elements that greatly increase the strength of the material, the amount of addition is limited to 0.09% or less, and 0.05% or less, which is an appropriate range for a general high tensile low alloy steel.

Cu는 부식분위기에서 안정적인 녹층을 형성하여 내부식성을 향상시키는 원소로서, 통상 0.1% 이상 첨가되는데, 그 함량이 0.5% 이상으로 과도하게 첨가되면 열연강판의 표면상태를 거칠게 하기 때문에 바람직하지 않다.Cu is an element which improves corrosion resistance by forming a stable rust layer in a corrosive atmosphere, and is usually added in an amount of 0.1% or more, but it is not preferable because Cu is excessively added in an amount of 0.5% or more.

Cr은 Cu와 같이 안정적인 녹층을 형성시키는 원소로서, 해수 분위기에서의 내식성을 크게 향상시키기 위해, 0.5~1.5%로 첨가하는 것이 바람직하다.Cr is an element which forms a stable rust layer like Cu, and is preferably added at 0.5 to 1.5% in order to greatly improve the corrosion resistance in seawater atmosphere.

Ni은 일반적으로 Cu 첨가 강에 있어 주조시 발생하는 주조 균열을 방지하기 위해 첨가되는 원소로서, 그 함량은 통상 첨가되는 양인 0.1~0.5%로 설정하는 것이 바람직하다.Ni is generally an element added in order to prevent casting cracks generated during casting in Cu-added steel, and the content thereof is preferably set to 0.1 to 0.5%, which is an added amount.

다음 Ca은 본 발명의 특징적인 원소로서, 강중 MnS 개재물을 CaS계의 구상 개재물로 치환시켜서, MnS 개재물 형성에 의한 소재의 연성 및 가공성 열화를 억제하는 효과가 매우 크다. 또한, Ca는 그 자체로도 내식성 향상효과가 큰 원소이다. 이와 같은 효과를 얻기 위해서는, 그 함량이 최소 0.001%은 되어야 하지만, 과잉 첨가되면 산화물계 비금속 개재물량이 증가되어 충격인성을 저하시키기 때문에, 상한은 0.005%로 설정하는 것이 바람직하다.Next, Ca is a characteristic element of the present invention, and the MnS inclusions in steel are replaced by CaS-based spherical inclusions, and the effect of suppressing the ductility and workability deterioration of the material due to MnS inclusions is very high. In addition, Ca is an element having a large effect of improving corrosion resistance in itself. In order to obtain such an effect, the content thereof should be at least 0.001%, but if it is added excessively, the amount of the oxide-based nonmetal inclusions increases and the impact toughness is lowered. Therefore, the upper limit is preferably set to 0.005%.

한편, V은 소재의 강도를 크게 증가시키는 역할을 하는 원소로서, 본 발명에서는 통상의 고장력 저합금강에 적절한 범위인 0.01~0.07%의 량으로 첨가될 수 있다.On the other hand, V is an element that plays a role of greatly increasing the strength of the material, in the present invention can be added in an amount of 0.01 ~ 0.07% which is a suitable range for the normal high-strength low alloy steel.

상기와 같이 조성된 강은 다음과 같은 조건으로 제조되는 것이 바람직하다.The steel formed as described above is preferably manufactured under the following conditions.

즉, 상기의 화학조성을 지닌 강은 1100~1300℃로 재가열하고 압연종료온도를 900~800℃ 범위로 하여 압연을 실시한 후, 적어도 20℃/sec 이상의 냉각속도로 수냉하고 450~550℃의 온도로 권취한다.That is, the steel having the above chemical composition is reheated to 1100 ~ 1300 ℃ and rolling is carried out with a rolling end temperature in the range of 900 ~ 800 ℃, water cooled at a cooling rate of at least 20 ℃ / sec or more at a temperature of 450 ~ 550 ℃ Wind up.

상기 재가열온도가 1100℃ 보다 낮으면 주조시 형성된 응고 조직의 파괴가 불충분하여 중심편석이 잘 발달되기 때문에, 최종 형성된 결정립의 혼립이 발생되어 가공성 및 충격인성이 현저히 발생한다. 반면에 재가열온도가 1300℃ 보다 높으면 산화에 의한 스케일 형성이 촉진되어 슬라브의 두께 감소량이 크고 재가열시 결정립 조대화에 따라 충격인성이 저하되는 단점이 있다. 또한, 가열 원단위의 상승으로 인해 경제적인 손실이 크다.When the reheating temperature is lower than 1100 ° C., the breakage of the solidified structure formed during casting is insufficient, so that the center segregation is well developed, and the final formed crystal grains are generated, resulting in remarkable workability and impact toughness. On the other hand, when the reheating temperature is higher than 1300 ° C, the formation of scale by oxidation is promoted, and thus, the thickness reduction of the slab is large and the impact toughness is lowered due to grain coarsening when reheating. In addition, the economic loss is large due to the rise of the heating raw unit.

상기 압연종료온도가 900℃보다 높으면 두께 전반에 걸쳐 균일한 열간압연이 이루어지지 않아 결정립 미세화가 불충분하게 되고, 이에 따라 결정립 조대화에 기인한 충격인성의 저하가 나타난다. 반대로, 압연마무리 온도가 700℃미만인 경우에는, 오스테나이트/페라이트 변태의 2상역에서 열간압연을 마무리하게 되어, 결정립 조대화 및 혼립이 유발되기 때문에 충격인성 및 가공성의 저하를 초래한다.If the end temperature of the rolling is higher than 900 ° C., uniform hot rolling is not performed throughout the thickness, resulting in insufficient grain refinement, resulting in a decrease in impact toughness due to grain coarsening. On the contrary, when the rolling finish temperature is less than 700 DEG C, hot rolling is finished in the two-phase zone of austenite / ferrite transformation, resulting in grain coarsening and mixing, resulting in deterioration of impact toughness and workability.

상기 냉각속도가 20℃/sec 미만이면, 페라이트 결정립의 성장이 촉진되어 상대적으로 조대한 결정립이 형성하게 되고, 이로인해 충격인성 및 강도 저하가 동시에 발생하게 된다.If the cooling rate is less than 20 ° C / sec, the growth of ferrite grains is promoted to form relatively coarse grains, thereby causing impact toughness and strength reduction simultaneously.

상기 권취온도가 550℃보다 높으면, 소재의 강도가 저하되어 목적하는 인장강도 80kg/㎟을 달성할 수 없고, 450℃ 미만이면 강도의 증가가 과도하여 상대적으로 연신율의 급격한 저하를 초래하기 때문에 바람직하지 않다.If the coiling temperature is higher than 550 ℃, the strength of the material is lowered to achieve the desired tensile strength of 80kg / mm2, and less than 450 ℃ is not preferable because the increase in strength is excessive to cause a relatively sharp decrease in elongation not.

이하, 실시예를 통해 본 발명을 보다 상세히 설명한다.Hereinafter, the present invention will be described in more detail with reference to Examples.

(실시예 1)(Example 1)

하기 표1과 같이 조성된 강에 대하여, 내후성 시험을 실시하고 그 평가결과를 하기 표2에 나타내었다.For the steel composition as shown in Table 1, the weather resistance test was performed and the evaluation results are shown in Table 2 below.

내후성 시험은, 다음과 같은 조건으로 실시하였다.The weather resistance test was performed on condition of the following.

염수분무: 5% NaCl, 30℃, 13분Brine spray: 5% NaCl, 30 ° C, 13 minutes

습식(humid): 80%RH, 30℃, 60분Humid: 80% RH, 30 ℃, 60 minutes

건조: 50%RH, 40℃, 30분Drying: 50% RH, 40 ° C., 30 minutes

세척: 35%RH, 40℃, 10분Wash: 35% RH, 40 ° C., 10 minutes

건조: 35%RH, 40℃, 80분Drying: 35% RH, 40 ° C, 80 minutes

강종Steel grade 화학성분(중량%)Chemical composition (% by weight) CC SiSi MnMn PP SS AlAl NbNb TiTi NiNi CuCu CrCr CaCa VV 발명강1Inventive Steel 1 0.070.07 0.40.4 1.41.4 0.030.03 0.0030.003 0.030.03 0.050.05 0.030.03 0.30.3 0.30.3 1.01.0 0.00200.0020 －－ 발명강2Inventive Steel 2 0.060.06 0.30.3 1.21.2 0.020.02 0.0040.004 0.030.03 0.050.05 0.020.02 0.30.3 0.30.3 0.90.9 0.00250.0025 0.040.04 비교강1Comparative Steel 1 0.200.20 0.250.25 1.31.3 0.030.03 0.0050.005 0.030.03 0.040.04 －－ 0.30.3 0.30.3 1.01.0 0.00300.0030 －－ 비교강2Comparative Steel 2 0.070.07 0.30.3 1.51.5 0.150.15 0.0050.005 0.040.04 0.040.04 0.0150.015 0.250.25 0.350.35 1.01.0 0.00350.0035 －－ 비교강3Comparative Steel 3 0.060.06 0.20.2 1.01.0 0.0040.004 0.0040.004 0.0250.025 0.050.05 0.020.02 0.20.2 0.30.3 0.30.3 0.00150.0015 －－ 비교강4Comparative Steel 4 0.090.09 0.350.35 1.21.2 0.040.04 0.0050.005 0.050.05 0.040.04 －－ 0.250.25 0.250.25 0.80.8 －－ 0.040.04

강종Steel grade 부식정도(무게감량(g/㎠))Corrosion degree (weight loss (g / ㎠)) 내후성Weather resistance 발명강1Inventive Steel 1 0.00690.0069 우수Great 발명강2Inventive Steel 2 0.00800.0080 우수Great 비교강1Comparative Steel 1 0.01700.0170 불량Bad 비교강2Comparative Steel 2 0.00920.0092 우수Great 비교강3Comparative Steel 3 0.01630.0163 불량Bad 비교강4Comparative Steel 4 0.00830.0083 우수Great

상기 표2에 나타난 바와 같이, 비교강(1) 및 비교강(3)은 부식정도가 커서 내후성이 불량하고, 비교강(2) 및 비교강(4)는 내후성은 우수하였으나,발명강(1),(2) 보다는 부식정도가 큰 것을 알 수 있다.As shown in Table 2, Comparative steel (1) and Comparative steel (3) has a high degree of corrosion and poor weather resistance, Comparative steel (2) and Comparative steel (4) has excellent weather resistance, but the invention steel (1 ), It can be seen that the degree of corrosion is greater than (2).

(실시예 2)(Example 2)

실시예1의 표1에서 발명강(1,2) 및 비교강(2,4)를 이용하여, 하기 표3과 같은 조건으로 열연강판을 제조하고, 기계적 성질 및 가공특성을 평가하여 그 결과를 하기 표4에 나타내었다.Using the inventive steel (1, 2) and comparative steel (2, 4) in Table 1 of Example 1, a hot-rolled steel sheet was prepared under the conditions as shown in Table 3 below, the mechanical properties and processing characteristics were evaluated to evaluate the results. It is shown in Table 4 below.

구분division 사용강종Steel grade used 재가열온도(℃)Reheating Temperature (℃) 압연종료온도(℃)Rolling end temperature (℃) 냉각속도(℃/s)Cooling rate (℃ / s) 권취온도(℃)Winding temperature (℃) 발명재1Invention 1 발명강1Inventive Steel 1 10001000 850850 2020 534534 발명재2Invention 2 발명강2Inventive Steel 2 12001200 850850 2525 540540 비교재1Comparative Material 1 발명강1Inventive Steel 1 11801180 700700 2525 550550 비교재2Comparative Material 2 11701170 10001000 2525 530530 비교재3Comparative Material 3 12501250 89508950 55 520520 비교재4Comparative Material 4 12701270 870870 2020 620620 비교재5Comparative Material 5 12301230 865865 2222 400400 비교재6Comparative Material 6 11901190 860860 2020 515515 비교재7Comparative Material7 발명강2Inventive Steel 2 11901190 10151015 2525 540540 비교재8Comparative Material 8 12401240 825825 2121 640640 비교재9Comparative Material 9 12051205 870870 2626 410410 비교재10Comparative Material 10 비교강2Comparative Steel 2 12201220 850850 2222 545545 비교재11Comparative Material 11 12201220 880880 2525 510510 비교재12Comparative Material 12 12201220 835835 2828 480480 비교재13Comparative Material 13 비교강4Comparative Steel 4 11801180 850850 2020 525525 비교재14Comparative Material14 11801180 870870 2525 510510

구분division 항복강도(kg/㎟)Yield strength (kg / ㎡) 인장강도(kg/㎟)Tensile Strength (kg / ㎡) 연신율(%)Elongation (%) 충격인성(0℃)(J)Impact Toughness (0 ℃) (J) 굽힘가공성Bendability 발명재1Invention 1 67.567.5 81.081.0 19.119.1 23.523.5 균열발생Cracking 발명재2Invention 2 68.468.4 80.380.3 23.223.2 53.453.4 양호Good 비교재1Comparative Material 1 72.372.3 83.283.2 19.819.8 12.512.5 비교재2Comparative Material 2 65.165.1 81.781.7 18.618.6 14.714.7 비교재3Comparative Material 3 54.254.2 73.273.2 31.631.6 45.345.3 비교재4Comparative Material 4 57.857.8 68.968.9 32.532.5 50.250.2 비교재5Comparative Material 5 75.875.8 92.792.7 11.011.0 26.726.7 비교재6Comparative Material 6 69.769.7 84.584.5 24.624.6 38.038.0 비교재7Comparative Material7 66.866.8 82.282.2 17.917.9 10.510.5 비교재8Comparative Material 8 56.256.2 75.875.8 29.529.5 57.057.0 비교재9Comparative Material 9 76.976.9 91.291.2 10.110.1 37.037.0 비교재10Comparative Material 10 67.667.6 80.380.3 18.818.8 13.513.5 비교재11Comparative Material 11 69.569.5 82.582.5 17.617.6 9.89.8 비교재12Comparative Material 12 71.271.2 82.182.1 18.218.2 7.57.5 비교재13Comparative Material 13 65.265.2 82.082.0 20.120.1 25.825.8 균열발생Cracking 비교재14Comparative Material14 69.169.1 79.279.2 18.218.2 24.624.6 균열발생Cracking

상기 표4에 나타난 바와 같이, 내후성이 우수한 발명강(1),(2)와 비교적 우수한 비교강(2),(4)로 제조된 경우에 있어서, 본 발명의 제조조건을 만족시킨 발명재(1),(2)는 기계적 성질 및 가공성도 우수한 것을 알 수 있다.As shown in Table 4 above, when the invention steel (1), (2) and the comparative steels (2), (4) excellent in weather resistance are manufactured, the invention material that satisfies the manufacturing conditions of the present invention ( It can be seen that 1) and (2) are also excellent in mechanical properties and workability.

상기한 바와 같이, 본 발명에 의하면, 내후성과 기계적 특성을 동시에 향상할 수 있기 때문에, 극히 부가가치가 높은 열연강판으로 제조할 수 있고, 또한 부수적인 처리가 필요치 않아 제조시 경제성을 크게 향상시킬 수 있는 효과가 있는 것이다.As described above, according to the present invention, since the weather resistance and the mechanical properties can be improved at the same time, it is possible to manufacture a hot rolled steel sheet having a very high value-added value, and it is possible to greatly improve the economics at the time of manufacture since no additional treatment is required. It works.

Claims (2)

중량%로, C:0.02~0.12%, Si:0.7% 이하, Mn:0.5~2.0%, P:0.05% 이하, S:0.01% 이하, Al:0.01~0.07%, Nb:0.09% 이하, Ti:0.05% 이하, Ni:0.1~0.5%, Cu:0.1~0.5%, Cr:0.5~1.5%, 단독 혹은 복합으로 Ca:0.001~0.005%, 잔부 Fe 및 기타 불가피한 불순물이 함유되는 강을 1100~1300℃로 재가열하고 마무리 압연온도를 900~800℃ 범위로 하여 열간압연한 후, 20℃/sec 이상의 냉각속도로 냉각하고 450~550℃의 온도로 권취하는 인장강도 80kg/㎟급 고가공성 고내후성 열연강판의 제조방법By weight%, C: 0.02 to 0.12%, Si: 0.7% or less, Mn: 0.5 to 2.0%, P: 0.05% or less, S: 0.01% or less, Al: 0.01 to 0.07%, Nb: 0.09% or less, Ti : 0.05% or less, Ni: 0.1 ~ 0.5%, Cu: 0.1 ~ 0.5%, Cr: 0.5 ~ 1.5%, alone or in combination with Ca: 0.001 ~ 0.005%, balance Fe and other unavoidable impurities 1100 ~ After reheating to 1300 ℃, hot rolling with finishing rolling temperature in the range of 900 ~ 800 ℃, cooling at 20 ℃ / sec or higher cooling rate and winding at 450 ~ 550 ℃ temperature, 80kg / mm2 high processability, high weatherability Method of manufacturing hot rolled steel sheet 제 1항에 있어서, 상기 강성분 중 V:0.01~0.07%가 추가로 첨가되는 것을 특징으로 하는 인장강도 80kg/㎟급 고강공성 고내후성 열연강판의 제조방법.According to claim 1, V: 0.01% to 0.07% of the steel component is added, characterized in that the tensile strength of 80kg / mm2 high steel porosity high weather resistance hot-rolled steel sheet manufacturing method.
KR1020000070188A 2000-11-24 2000-11-24 A METHOD FOR MANUFACTURING HOT ROLLED STEEL SHEET OF TENSILE STRENGTH 80kg/㎟ GRADE WITH EXCELLENT WEATHER RESISTANCE AND WORKABILITY KR20020040213A (en)

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Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR100643361B1 (en) * 2005-06-23 2006-11-10 주식회사 포스코 A method for manufacturing precipitation hardening type steel for line pipe with low yeild ratio and a precipitation hardening type steel for line pipe manufactured by the method
KR101236009B1 (en) * 2010-11-26 2013-02-21 현대제철 주식회사 Api steel sheet with excellent heat treatment properties for oil tubular country goods and method of manufacturing the api steel sheet
KR101235944B1 (en) * 2010-11-26 2013-02-21 현대제철 주식회사 High strength api hot-rolled steel sheet with low yield ratio for american petroleum institute and method of manufacturing the api hot-rolled steel sheet
KR101277903B1 (en) * 2011-10-28 2013-06-21 현대제철 주식회사 Hot-rolled steel sheet and method of manufacturing the hot-rolled steel sheet
CN108826634A (en) * 2018-07-16 2018-11-16 广东美的制冷设备有限公司 wind wheel
CN114161725A (en) * 2021-12-13 2022-03-11 湖南平安医械科技有限公司 Automatic assembling device for intravenous needle on disposable infusion apparatus
CN115948697A (en) * 2022-12-22 2023-04-11 武汉钢铁有限公司 500 MPa-grade weather-proof coating-free hot-rolled rod wire and rolling process thereof

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR850001298A (en) * 1983-07-25 1985-03-16 포항종합제철 주식회사 Manufacturing method of high strength steel with excellent weather resistance
JPH032321A (en) * 1989-05-30 1991-01-08 Nippon Steel Corp Manufacture of high strength weather-resisting hot rolled steel sheet
JPH05195056A (en) * 1991-08-28 1993-08-03 Kobe Steel Ltd Production of steel sheet having high ductility and high strength
JPH07118792A (en) * 1993-10-21 1995-05-09 Sumitomo Metal Ind Ltd High-strength hot rolled steel plate and its production
JP2000212688A (en) * 1999-01-21 2000-08-02 Nippon Steel Corp High strength hot rolled steel plate good in shape after cutting and its production
KR100356706B1 (en) * 1998-12-29 2002-12-18 주식회사 포스코 Hot rolled steel sheet with excellent workability and weather resistance and manufacturing method

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR850001298A (en) * 1983-07-25 1985-03-16 포항종합제철 주식회사 Manufacturing method of high strength steel with excellent weather resistance
JPH032321A (en) * 1989-05-30 1991-01-08 Nippon Steel Corp Manufacture of high strength weather-resisting hot rolled steel sheet
JPH05195056A (en) * 1991-08-28 1993-08-03 Kobe Steel Ltd Production of steel sheet having high ductility and high strength
JPH07118792A (en) * 1993-10-21 1995-05-09 Sumitomo Metal Ind Ltd High-strength hot rolled steel plate and its production
KR100356706B1 (en) * 1998-12-29 2002-12-18 주식회사 포스코 Hot rolled steel sheet with excellent workability and weather resistance and manufacturing method
JP2000212688A (en) * 1999-01-21 2000-08-02 Nippon Steel Corp High strength hot rolled steel plate good in shape after cutting and its production

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR100643361B1 (en) * 2005-06-23 2006-11-10 주식회사 포스코 A method for manufacturing precipitation hardening type steel for line pipe with low yeild ratio and a precipitation hardening type steel for line pipe manufactured by the method
KR101236009B1 (en) * 2010-11-26 2013-02-21 현대제철 주식회사 Api steel sheet with excellent heat treatment properties for oil tubular country goods and method of manufacturing the api steel sheet
KR101235944B1 (en) * 2010-11-26 2013-02-21 현대제철 주식회사 High strength api hot-rolled steel sheet with low yield ratio for american petroleum institute and method of manufacturing the api hot-rolled steel sheet
KR101277903B1 (en) * 2011-10-28 2013-06-21 현대제철 주식회사 Hot-rolled steel sheet and method of manufacturing the hot-rolled steel sheet
CN108826634A (en) * 2018-07-16 2018-11-16 广东美的制冷设备有限公司 wind wheel
CN114161725A (en) * 2021-12-13 2022-03-11 湖南平安医械科技有限公司 Automatic assembling device for intravenous needle on disposable infusion apparatus
CN115948697A (en) * 2022-12-22 2023-04-11 武汉钢铁有限公司 500 MPa-grade weather-proof coating-free hot-rolled rod wire and rolling process thereof
CN115948697B (en) * 2022-12-22 2024-05-14 武汉钢铁有限公司 500 MPa-level weather-resistant coating-free hot rolled rod wire and rolling process thereof

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