KR100910467B1 - Method of manufacturing double reduced steel sheet with excellent formability - Google Patents

Method of manufacturing double reduced steel sheet with excellent formability Download PDF

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KR100910467B1
KR100910467B1 KR1020020084686A KR20020084686A KR100910467B1 KR 100910467 B1 KR100910467 B1 KR 100910467B1 KR 1020020084686 A KR1020020084686 A KR 1020020084686A KR 20020084686 A KR20020084686 A KR 20020084686A KR 100910467 B1 KR100910467 B1 KR 100910467B1
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rolling
steel sheet
steel
cold
reduction rate
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KR20040058466A (en
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김재익
김병수
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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
    • B21B37/16—Control of thickness, width, diameter or other transverse dimensions
    • 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
    • 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
    • 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
    • C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
    • 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
    • B21B2001/221—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 cold-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
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B2265/00—Forming parameters
    • B21B2265/14—Reduction rate

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (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

본 발명은 성형성이 우수한 2차 압연 강판을 제조하는 방법에 관한 것이다. 이 제조방법은 중량%로, 탄소(C):0.003%이하, 망간(Mn):0.3~0.6%, 황(S):0.015%이하, 알루미늄(Al):0.04~0.09%, 질소(N):0.003% 이하, 티타늄(Ti):0.01~0.02%, 보론 :0.0005~0.002%, 나머지 기타 불가피한 불순물과 Fe로 조성되고, Ti*/C(%):-0.95~-0.15[단, Ti*=Ti(%)-(48/32)S(%)-(48/14)N(%)], B/N 중량비:0.45~0.6를 만족하는 알루미늄 킬드강을 오스테나이트 영역에서 균질화 처리하여 910~930℃의 마무리압연조건으로 열간압연하고, 600~700℃에서 권취한 다음, 1차 냉간 압하율(CR1)과 2차 냉간압하율(CR2)이 다음의 조건, 83≤CR1≤90, 95≤(CR1+0.9×CR2 )≤120으로 냉간압연하는 것을 포함한다. 이 제조방법에서는 저항 용접성, 압연성 및 연속소둔에서의 통판성과 아울러 가공용 소재로써 적용할 수 있을 정도의 넥킹 가공성이 우수한 2차압연강판을 제공할 수 있다. The present invention relates to a method for producing a secondary rolled steel sheet excellent in formability. This manufacturing method is% by weight, carbon (C): 0.003% or less, manganese (Mn): 0.3-0.6%, sulfur (S): 0.015% or less, aluminum (Al): 0.04-0.09%, nitrogen (N) : 0.003% or less, Titanium (Ti): 0.01 ~ 0.02%, Boron: 0.0005 ~ 0.002%, and other remaining unavoidable impurities and Fe, Ti * / C (%):-0.95 ~ -0.15 [Ti * = Ti (%)-(48/32) S (%)-(48/14) N (%)] and B / N weight ratio: 0.45 to 0.6. Hot rolled under finishing rolling conditions of ˜930 ° C., wound up at 600 ° C. to 700 ° C., and then the primary cold reduction rate (CR 1 ) and the secondary cold reduction rate (CR 2 ) are the following conditions, 83≤CR 1 ≤ Cold rolling to 90, 95 ≦ (CR 1 + 0.9 × CR 2 ) ≦ 120. In this manufacturing method, it is possible to provide a secondary rolled steel sheet excellent in resistance weldability, rolling property, and sheeting in continuous annealing, and necking workability that can be applied as a material for processing.

2회압연, 비시효, 넥킹, 주석도금, 연속소둔2 rolls, unaging, necking, tin plating, continuous annealing

Description

가공성이 우수한 2차 압연 강판 제조 방법{METHOD OF MANUFACTURING DOUBLE REDUCED STEEL SHEET WITH EXCELLENT FORMABILITY}Method for manufacturing secondary rolled steel sheet with excellent workability {METHOD OF MANUFACTURING DOUBLE REDUCED STEEL SHEET WITH EXCELLENT FORMABILITY}

본 발명은 성형성이 우수한 2차 압연 강판을 제조하는 방법에 관한 것으로, 보다 상세하게는 극저탄소 베이스(Base)의 알루미늄-킬드(Al-killed)강에 탄화물 형성 원소인 Ti 첨가량 및 Ti*/C 원자비와 B/N 중량비를 적절히 관리하고 열연 조건을 제어하는 가공성이 우수한 2차 압연 강판의 제조방법에 관한 것이다. The present invention relates to a method for manufacturing a secondary rolled steel sheet having excellent formability, and more particularly, Ti addition amount and Ti * / as a carbide forming element in an ultra-low carbon base Al-killed steel. The present invention relates to a method for producing a secondary rolled steel sheet having excellent workability for appropriately managing the C atomic ratio and the B / N weight ratio and controlling hot rolling conditions.

캔(Can)용 소재로 사용되는 철강 소재인 주석도금강판은 대부분 소재의 두께가 얇으므로 록크웰 표면 경도인 HR30T로 측정되는 조질도에 의해 재질을 구분한다. 주석도금 강판은 내용물을 저장하기 위한 캔을 만들기 위해서 주석도금원판의 표면에 주석(Tin, 원소기호 Sn) 등을 도금하여 내식성을 부여하고 일정한 크기로 절단한 후 원형 또는 각형으로 가공하고 있다. 용기를 가공하는 방법으로는 용기가 뚜껑과 몸체(Body)의 2부분으로 구성되는 2-피스(Piece) 캔과 같이 용접을 하지 않고 가공하는 방법과, 캔의 구성이 몸통, 위 뚜껑(End) 및 아래 뚜껑(Bottom)의 3부분으로 이루어진 3-피스캔과 같이 용접 또는 접합에 의해 몸통을 체결하는 방법으로 나누어 진다.     Tin-plated steel sheet, which is a steel material used as a material for cans, is divided into materials by the roughness measured by the Rockwell surface hardness HR30T because most of the materials are thin. Tin-plated steel sheet is coated with tin (Tin, element symbol Sn) on the surface of tin-plated disc to make cans for storing the contents to give corrosion resistance, cut to a certain size, and processed into round or square. In order to process the container, the container is processed without welding, such as a two-piece can, which consists of two parts, a lid and a body. The can is composed of a body and an upper lid. And a three-piece can consisting of three parts of the bottom lid, and a method of fastening the body by welding or bonding.

2차 압연 강판이란 열연, 냉연 및 소둔을 거친 소재를 조질압연공정에서 비교적 높은 압하율을 가함으로써 소재의 강도를 상승시킨 강판을 의미한다. 2차압연용 소재의 대표적 용도인 캔용 2차 압연강판은 소재 강도 및 경도에 따라 등급을 나누고 있다. 대부분의 2차 압연용 소재의 경우 가공경화에 의해 강도는 상승하지만 그 반작용으로 연성이 급격히 감소하는 문제점이 있었다. 특히 2차 압연용 원판으로써 중저탄소강을 이용하여 연속소둔하는 경우에는 가공전 락카(Lacquer) 등의 건조를 위한 공정인 소부 단계에서 변형시효가 발생하여 소재의 연성을 더욱 감소되어 압축가공(넥킹가공)시 균열이 발생하는 요인으로 작용하여 왔다. 이와 같은 변형시효의 억제를 위하여 상소둔재를 이용하는 방안이 제안되었지만 상소둔재의 경우에도 소둔에 따른 시간이 장시간 소요되는 등 생산성이 떨어지고 제품의 재질이 불균일할 뿐만 아니라 2차 압연 강판의 표면 결함이 다발하여 작업성이 떨어지는 근본적인 문제점을 가지고 있었다. 이와 같은 문제점 해결을 위해 근년에 와서는 생산비가 적고 재질이 균일하며 평탄도와 표면 특성이 우수한 연속소둔 방식을 통한 2차 압연용 원판을 제조하고자 하는 방안이 적극적으로 검토되고 있다.
The secondary rolled steel sheet refers to a steel sheet in which the strength of the material is increased by applying a relatively high rolling reduction rate to the raw material subjected to hot rolling, cold rolling, and annealing in the temper rolling process. Secondary rolled steel sheet for cans, which is a typical use of secondary rolling materials, is divided into grades according to material strength and hardness. In the case of most secondary rolling materials, strength increases due to work hardening, but there is a problem in that ductility decreases rapidly due to the reaction. Particularly, in case of continuous annealing using low and medium carbon steel as the secondary rolling disc, deformation aging occurs in the baking step, which is a process for drying lacquer, etc. before processing, which further reduces the ductility of the material, thus compressing (necking) It has been a factor that causes cracks in). In order to suppress the strain aging, a method of using an annealing material has been proposed, but in the case of an annealing material, it takes a long time due to annealing, resulting in poor productivity and uneven material of the product. It had a fundamental problem of poor workability. In order to solve such a problem, in recent years, a method for manufacturing a secondary rolling disc through a continuous annealing method having a low production cost, a uniform material, and excellent flatness and surface properties has been actively studied.

현재 가공성, 특히 넥킹(Necking) 가공성이 요구되는 2차 압연 강판을 제조하는 방법으로는 주로 상소둔에 의해 조질도 T3급의 석도원판을 제조한 후 조질압연 공정에서 비교적 높은 압하율을 적용함으로써 목표로 하는 조질도를 확보하는 방안이 제안되어 있다. 그러나, 이들 소재의 경우 상소둔 공정으로 제조됨에 따른 생산비 증가, 생산공정 단속성과 같은 프로세스상의 문제를 제외하고도 표면 품질, 특히 산화층 등에 의한 2차압연판의 도금 특성이 나빠지는 문제점이 대두되므로 효율적인 가공용 2차압연판의 제조 방법으로 보기는 곤란하였다.
As a method of manufacturing secondary rolled steel sheets that require workability, in particular, necking workability, the target is mainly by manufacturing a roughness T3 grade stone plate by means of annealing and then applying a relatively high rolling reduction rate in the rough rolling process. A method of securing the quality of the matrix has been proposed. However, in the case of these materials, except for process problems such as production cost increase and production process interruption caused by the annealing process, the quality of the surface of the secondary rolled sheet due to the oxide layer is deteriorated. It was difficult to see by the manufacturing method of a secondary rolled sheet.

따라서, 본 발명은 용접 열영향부의 이상 조대립 형성을 억제하여 저항용접성이 우수하고 연속소둔공정에서의 작업성, 통판성, 넥킹가공성이 우수한 2차 압연 냉연강판의 제조방법을 제공하는데, 그 목적이 있다. Accordingly, the present invention provides a method for producing a secondary rolled cold rolled steel sheet excellent in resistance weldability and excellent workability, plateability, and necking workability in the continuous annealing process by suppressing abnormal coarse grain formation in the weld heat affected zone. There is this.

상기 목적을 달성하기 위한 본 발명의 냉연강판 제조방법은, 탄소(C):0.003중량%(간단히 %라고 함)이하, 망간(Mn):0.3~0.6%, 황(S):0.015%이하, 알루미늄(Al):0.04~0.09%, 질소(N):0.003% 이하, 티타늄(Ti):0.01~0.02%, 보론 :0.0005~0.002%, 나머지 기타 불가피한 불순물과 Fe로 조성되고, Ti*/C(%):-0.95~-0.15[단, Ti*=Ti(%)-(48/32)S(%)-(48/14)N(%)], B/N 중량비:0.45~0.6를 만족하는 알루미늄 킬드강을 오스테나이트 영역에서 균질화 처리하여 910~930℃의 마무리압연조건으로 열간압연하고, 600~700℃에서 권취한 다음, 1차 냉간 압하율(CR1)과 2차 냉간압하율(CR2)이 다음의 조건, 83≤CR1≤90, 95≤(CR1+0.9×CR2 )≤120으로 냉간압연하는 것을 포함한다.
Cold rolled steel sheet manufacturing method of the present invention for achieving the above object, carbon (C): 0.003% by weight (simply referred to as%) or less, manganese (Mn): 0.3 ~ 0.6%, sulfur (S): 0.015% or less, Aluminum (Al): 0.04 ~ 0.09%, Nitrogen (N): 0.003% or less, Titanium (Ti): 0.01 ~ 0.02%, Boron: 0.0005 ~ 0.002%, remaining other inevitable impurities and Fe, Ti * / C (%):-0.95 ~ -0.15 [Ti * = Ti (%)-(48/32) S (%)-(48/14) N (%)], B / N weight ratio: 0.45 ~ 0.6 The satisfactory aluminum-kilted steel is homogenized in the austenite region, hot rolled to a finish rolling condition of 910-930 ° C, wound at 600-700 ° C, and then subjected to primary cold reduction rate (CR 1 ) and secondary cold reduction rate. (CR 2) this involves the cold rolling with the following conditions ≤120, 83≤CR 1 ≤90, 95≤ (CR 1 + 0.9 × CR 2).

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

본 발명에서는 생산성이 높은 연속소둔 공정을 경유할 수 있으면서, 가공성, 특히 넥킹 가공성을 개선할 수 있는 방안을 연구하는 과정에서 완성된 것이다. In the present invention, while being able to go through a high productivity continuous annealing process, it is completed in the process of studying a method for improving the workability, especially necking workability.

본 발명에서는 극저탄소 베이스(Base)의 알루미늄-킬드(Al-killed)강에 탄화물 형성 원소인 Ti 첨가량 및 Ti*/C 원자비와 B/N 중량비를 적절히 관리하고 열연 조건을 제어하는 한편, 2차 압연 공정에서의 1차 압하율과 2차압하율의 조합에 의해 통상의 2차 압연강판의 가공시 문제가 되었던 변형 시효에 의한 연성 저감에 따른 스트레칭(Stretching) 가공성 열화 문제를 해결하고 연속소둔공정에서의 통판성, 용접성 등을 개선하는데, 특징이 있다.
In the present invention, the addition amount of Ti as a carbide-forming element and the Ti * / C atomic ratio and B / N weight ratio in the ultra-low carbon base Al-killed steel are properly managed and the hot rolling conditions are controlled. The combination of the primary reduction rate and the secondary reduction rate in the secondary rolling process solves the problem of deterioration in stretching workability due to the decrease in ductility due to the strain aging, which has been a problem in the processing of ordinary secondary rolled steel sheets. It is characterized by improving the mailability, weldability and the like.

탄소(C)의 함량은 0.003%이하가 바람직하다.The content of carbon (C) is preferably 0.003% or less.

C의 첨가에 따른 시효 열화 및 결정립 미세화에 의한 재질 경화 효과를 억제하고, 제강 공정에서의 탈탄에 의한 추가적인 제조원가 상승을 억제함과 아울러 첨가되는 고가의 티타늄과의 원자비를 고려하여 0.003% 이하로 한정하는 것이 바람직하다.
It suppresses the material hardening effect by aging deterioration and grain refinement by adding C, suppresses further manufacturing cost increase by decarburization in steelmaking process, and lowers it to 0.003% or less in consideration of the atomic ratio with expensive titanium added It is preferable to limit.

망간(Mn)의 함량은 0.3~0.6%가 바람직하다. The content of manganese (Mn) is preferably 0.3 to 0.6%.

Mn은 황에 의한 적열 취성을 억제하고 원판의 적정 강도를 확보하기 위해서는 0.3% 이상 첨가한다. 그러나, Mn의 첨가량이 0.6%를 초과하면 소입성을 증가시켜 베이나이트와 같은 경한 2상 조직을 형성하여 재질 편차를 유발할 뿐만 아니라, 미소 편 석(micro-segregation)을 일으켜 냉간 압연성 및 성형성을 나쁘게 한다.
Mn is added 0.3% or more in order to suppress the red brittleness by sulfur and to secure the appropriate strength of the original. However, when the amount of Mn added exceeds 0.6%, the hardenability increases to form a hard two-phase structure such as bainite, which causes material variation, and also causes micro-segregation, resulting in cold rolling and formability. Makes it bad.

황(S)의 함량은 0.015%가 바람직하다. The content of sulfur (S) is preferably 0.015%.

황(S)은 일부가 강중 망간, 티타늄 등과 결합하여 설파이드(Sulfide)계 석출물을 형성하므로 황이 너무 많은 경우 이들 석출물의 크기가 조대화되어 재질이 급격히 연화되어 목표 재질을 확보하기 곤란하며, 또한 첨가되는 Ti량의 제어가 곤란하므로 그 첨가량을 0.015% 이하로 한정하는 것이 바람직하다.
Sulfur (S) is partially combined with manganese, titanium, etc. in steel to form sulfide-based precipitates, so when the sulfur is too large, the size of these precipitates is coarsened and the material is softened rapidly, making it difficult to secure the target material. Since it is difficult to control the amount of Ti to be added, it is preferable to limit the addition amount to 0.015% or less.

알루미늄(Al)의 함량은 0.04~0.09%가 바람직하다.The content of aluminum (Al) is preferably 0.04 to 0.09%.

알루미늄(Al)은 알루미늄-킬드강에서 탈산제 및 시효에 의한 재질 열화를 방지할 목적으로 첨가되는 원소로서 이와 같은 효과를 얻기 위해서는 최소한 0.04% 이상의 첨가하는 것이 바람직하다. 그러나, Al이 0.09%초과하면 탈산 효과는 포화되는 반면에 알루미늄-옥사이드(Al2O3)와 같은 표면 개재물이 급증하여 연주 및 열연재의 표면 특성을 악화시키므로 Al 첨가 범위를 0.04~0.09%로 하는 것이 바람직하다.
Aluminum (Al) is an element added for the purpose of preventing material deterioration by deoxidizer and aging in aluminum-kilted steel, and in order to obtain such an effect, at least 0.04% or more is preferably added. However, when Al exceeds 0.09%, the deoxidation effect is saturated, while surface inclusions such as aluminum oxide (Al 2 O 3 ) increase rapidly, deteriorating the surface characteristics of the performance and hot rolled material, so the Al addition range is 0.04 to 0.09%. It is desirable to.

질소(N)의 함량은 0.003%이하가 바람직하다. The content of nitrogen (N) is preferably 0.003% or less.

질소(N)는 강내에 침입하여 강화 특성을 나타내는 대표적인 침입형 원소이며, 보론 및 티타늄과 반응하여 질화물계 석출물을 형성한다. 질소가 0.003%초과하면 변형시효에 의한 가공 결함의 원인이 될 뿐만 아니라 질화물의 과다 석출에 의한 저항용접성 등의 확보가 곤란하다.
Nitrogen (N) is a representative invasive element that penetrates into the steel and exhibits reinforcing properties, and reacts with boron and titanium to form nitride-based precipitates. When nitrogen exceeds 0.003%, it not only causes processing defects due to strain aging but also secures resistance weldability due to excessive precipitation of nitride.

티타늄(Ti)의 함량은 0.01~0.02%가 바람직하다. The content of titanium (Ti) is preferably 0.01 to 0.02%.

티타늄(Ti)은 강내 고용 원소인 탄소, 질소 등과 결합하여 티타늄계 석출물을 형성하여 연속소둔재의 변형시효를 억제할 목적으로 첨가되는 원소로서, 이와 같은 효과를 확보하기 위해서는 0.01% 이상의 Ti를 첨가하여야 한다. 반면에 Ti이 0.02% 초과하면 미세 석출물의 생성에 따른 재결정온도 상승 요인이 되어 극박재의 소둔 통판성을 나쁘게 하며, 또한 연주시 연주 노즐(Nozzle) 막힘과 같은 결함을 유발하는 요인으로 작용하므로 Ti의 첨가량은 0.01~0.02%로 설정하는 것이 바람직하다.
Titanium (Ti) is an element added to suppress the strain aging of the continuous annealing material by forming titanium-based precipitates in combination with carbon, nitrogen, etc., solid solution elements in the steel, and at least 0.01% of Ti is added to secure such effects. shall. On the other hand, when Ti exceeds 0.02%, it causes an increase in recrystallization temperature due to the generation of fine precipitates, which deteriorates the annealing and sending property of the ultrathin material, and also acts as a factor that causes defects such as clogging of the nozzle during playing. It is preferable to set the addition amount of to 0.01 to 0.02%.

보론(B)의 함량은 0.0005~0.002%가 바람직하다. The content of boron (B) is preferably 0.0005 to 0.002%.

강내 질소와 결합, 석출물을 형성하는 보론(B)은 일부 고용 상태로 존재하면서 저항 용접시 결정립계(grain boundary)를 강화시켜 용접 열영향부의 결정립 성장을 억제하여 용접 부위에서의 파단을 억제하는 효과를 발휘하며, 이와 같이 효과를 확보하기 위해서는 0.0005% 이상으로 B이 첨가되어야 한다. 반면에 B이 0.002%를 초과하면 강의 재결정을 지연시켜 소둔 통판성을 저하시킬 뿐만 아니라 가공성도 현저히 나쁘게 하는 문제점이 있으므로 B 첨가량은 0.0005~0.002%로 제한하는 것이 바람직하다.
Boron (B), which bonds with nitrogen in the cavity and forms precipitates, exists in a partially solid solution state and strengthens grain boundaries during resistance welding, thereby suppressing grain growth at the weld heat affected zone and thus preventing fracture at the welded site. In order to secure the effect, B should be added at 0.0005% or more. On the other hand, when B exceeds 0.002%, the recrystallization of the steel may be delayed, thereby reducing the annealing and sheeting property, and also significantly reducing the workability. Therefore, the amount of B added is preferably limited to 0.0005 to 0.002%.

유효Ti(Ti*)/C의 원자비는 -0.95 ~ -0.15가 바람직하다. The atomic ratio of the effective Ti (Ti * ) / C is preferably -0.95 to -0.15.

한편 강 내에 존재하는 탄소, 질소와 같은 고용 원소를 효과적으로 제어하여 저항 용접성 및 소둔공정에서 두께가 얇은 소재의 통판성을 확보하기 위해서는 이들 원소들과 화합물을 형성하는 원소들과의 관계를 고려하여 첨가비를 관리하는 것도 필요하다. Ti는 C, N, S 등과 결합하여 다양한 석출물을 형성하므로 가공성 및 고용원소들에 의한 변형시효를 억제하면서도 소둔 통판성을 확보하기 위해서는 유효 Ti[Ti*=Ti(%)-(48/32)S(%)-(48/14)N(%)]에 대한 탄소의 원자비, 즉 Ti*/C 원자비를 관리하여야 한다. Ti*/C 원자비가 -0.95미만이면 강중 고용 원소를 충분히 석출시키지 못함에 따라 2차 압연판을 성형시 변형시효가 발생하여 충분한 가공성을 확보하는 것이 곤란하다. 반면에 Ti*/C 원자비 -0.15초과이면 미세 석출물이 석출함에 따라 강의 재결정을 지연시키므로 소둔 통판성을 확보하는 것이 곤란하다. 또한, 고가의 Ti 첨가량이 증가함에 따라 제조 원가가 상승하며, 열연 재질이 경화되어 냉간압연성을 나쁘게 하는 요인으로 작용하므로, 본 발명에서는 유효Ti(Ti*)에 대한 C 원자비, Ti*/C를 -0.95 ~ -0.15로 제한하는 것이 바람직하다.
On the other hand, in order to effectively control solid solution elements such as carbon and nitrogen present in the steel, and to secure resistance weldability and flowability of thin material in annealing process, it is added considering the relationship between these elements and the elements forming the compound. It is also necessary to manage the rain. Ti forms various precipitates by combining with C, N, S, etc., and thus, effective Ti [Ti * = Ti (%)-(48/32) The atomic ratio of carbon to S (%)-(48/14) N (%)], ie Ti * / C atomic ratio, should be controlled. If the Ti * / C atomic ratio is less than -0.95, it is difficult to secure sufficient workability because deformation age occurs in forming the secondary rolled plate due to insufficient precipitation of solid solution elements in steel. On the other hand, if the Ti * / C atomic ratio is more than -0.15, it is difficult to secure annealing ductility because it delays recrystallization of the steel as the fine precipitate precipitates. In addition, the manufacturing cost increases as the amount of expensive Ti added increases, and the hot rolled material hardens and acts as a factor of worsening cold rolling property. In the present invention, the C atomic ratio to effective Ti (Ti *), Ti * / It is desirable to limit C to -0.95 to -0.15.

B/N의 중량비는 0.45~0.6이 바람직하다. The weight ratio of B / N is preferably 0.45 to 0.6.

질화물계 석출물을 형성하는 B은 B에 대한 N의 중량비를 관리함으로써 2차 압연강판의 가공성 및 저항 용접성을 확보하는 방안을 설정할 수 있다. 즉, B/N 중량비가 0.45미만이면 열연 단계에서 강중 모든 B이 N과 결합하여, 저항 용접시 용접 열영 향부 결정립의 이상 성장을 억제할 수 없을 뿐만 아니라 변형시효를 억제하기 위해 필요로 하는 Ti량을 증가시켜야 하는 문제점이 대두된다. 반면에 B/N 중량비 0.6 초과이면 2차 압연강판의 넥킹 가공성이 현저히 저하되므로 본 발명에서는 B/N 중량비를 0.45~0.6로 한정하는 것이 바람직하다.
B to form a nitride-based precipitate can be set to secure the workability and resistance weldability of the secondary rolled steel sheet by managing the weight ratio of N to B. That is, if the B / N weight ratio is less than 0.45, all the B in the steel are combined with N in the hot rolling step, and the amount of Ti required for suppressing abnormal aging of the grains of the weld heat affected zone during resistance welding cannot be suppressed. There is a problem that needs to be increased. On the other hand, when the B / N weight ratio is more than 0.6, since the necking workability of the secondary rolled steel sheet is significantly lowered, it is preferable to limit the B / N weight ratio to 0.45 to 0.6 in the present invention.

다음으로 상기와 같이 조성되는 강을 냉연강판으로 제조하는 방법을 설명한다.
Next, a method of manufacturing the steel formed as described above into a cold rolled steel sheet will be described.

먼저, 위의 조성으로 제조된 강을 오스테나이트 단상역에서 균질화 처리한다. First, the steel produced with the above composition is homogenized in an austenitic single phase zone.

슬라브 재가열 온도는 초기의 오스테나이트 조직이 가능한 한 조대화될 수 있는 오스테나이트 단상역으로 제한한다.
The slab reheat temperature is limited to the austenite single-phase zone where the initial austenite structure can be coarsened as much as possible.

상기와 같이 재가열하여 열간압연하는데, 이때의 마무리압연온도는 910~930℃가 바람직하다. 마무리압연 온도가 910℃미만이면 열간 압연 중에 압연 온도가 페라이트 영역으로 낮아져 조대한 결정립과 미세한 결정립이 공존하는 혼립이 발생하여 재질 편차를 유발할 뿐만 아니라 냉간 압연성을 나쁘게 하는 요인으로 작용한다. 반면에 마무리압연온도가 930℃ 초과이면 석출물 크기가 조대화되어 재질이 연화되고 이를 확보하기 위한 슬라브 가열 온도의 상승에 따른 스케일(Scale)의 발생이 증가하여 제품의 실수율을 떨어뜨리는 요인으로 작용한다.
Reheating and hot rolling as described above, the finish rolling temperature at this time is preferably 910 ~ 930 ℃. If the finish rolling temperature is less than 910 ℃, the rolling temperature is lowered to the ferrite region during hot rolling, resulting in coexistence of coarse grains and fine grains coexist, causing material variation and worsening cold rolling properties. On the other hand, if the finish rolling temperature is higher than 930 ℃, the precipitate size becomes coarse, softening the material and increasing the generation of scale due to the increase of the slab heating temperature to secure it. .

다음으로 권취하는데, 권취온도는 600~700℃가 바람직하다. 열연 권취공정은 알루 미늄 나이트라이트(AlN) 석출 및 소둔 통판성과 밀접한 관계를 가지는 단계이다. 권취온도가 600℃보다 낮으면 알루미늄계 질화물의 석출이 억제될 뿐만 아니라 열연판 폭 방향으로의 재질 편차가 크게 발생하여 냉간 압연성을 나쁘게 하는 요인으로 작용한다. 반면에 700℃ 초과의 권취온도에서는 열연 결정립이 성장하여 목표로 하는 경도의 확보가 곤란하다.
Next, although winding up, the winding temperature is preferably 600 to 700 ° C. The hot rolled winding process is a step that has a close relationship with the aluminum nitrite (AlN) precipitation and annealing mailing. If the coiling temperature is lower than 600 ℃, not only the precipitation of aluminum-based nitride is suppressed, but also material variation in the width direction of the hot-rolled sheet occurs largely to act as a factor that worsens cold rolling properties. On the other hand, when the coiling temperature is higher than 700 ° C, hot rolled grains grow, making it difficult to secure the target hardness.

다음으로 냉간압연하는데, 1차 냉간 압하율(CR1)과 2차 냉간압하율(CR2)이 다음의 조건, 83≤CR1≤90, 95≤(CR1+0.9×CR2)≤120으로 행하는 것이 바람직하다. Next, cold rolling, where the primary cold reduction rate (CR 1 ) and the secondary cold reduction rate (CR 2 ) is the following conditions, 83≤CR 1 ≤90, 95≤ (CR 1 + 0.9 × CR 2 ) ≤120 It is preferable to carry out by.

냉간 압하율은 열연 작업성 및 강의 재결정 거동과 밀접한 관계를 가지는 인자이다. 냉간 압하율이 낮아지면 재결정 현상의 구동력으로 작용하는 변형에너지가 감소하여 재결정을 지연시키는 효과를 발휘하지만, 반면에 주석 도금원판과 같이 두께가 얇은 소재의 열간압연판 두께가 얇아야 한다는 문제점이 있다. 얇은 두께의 열연판을 얻기 위해서는 온도 저하(Drop) 현상이 심하게 발생하여 권취 형상 제어가 곤란하고 열연공정의 부하를 증가시킬 뿐만 아니라 냉각 패턴을 변화시켜 재질 편차를 증가시키므로 냉간압연성도 저하된다. 반면에 냉간 압하율이 높으면 소재에 축적된 변형에너지가 증가하여 재결정을 촉진하는 효과가 있다. 그러므로, 본 발명법에서는 열간 및 냉간 압연성과 강의 재결정거동을 고려하여 적정 1차 냉간 압하율 범위를 설정한다. 1차 냉간압하율이 83%보다 낮으면 극박의 열연재를 생산하여야 하며, 이 경우 열연공정에 부하를 줄 뿐만 아니라 냉간압연성도 나쁘게 한다. 반면에 1차 냉간압하율이 90% 초과에서는 재결정온도가 낮아지는 반면에 2차 압연판의 연성을 확보하기 곤란하게 하므로 1차 냉간압하율은 83~90%로 한정하는 것이 바람직하다.
Cold rolling reduction is a factor that is closely related to hot workability and steel recrystallization behavior. If the cold reduction rate is lowered, the strain energy acting as the driving force of the recrystallization decreases and thus retards the recrystallization. On the other hand, there is a problem in that the thickness of the hot rolled sheet of a thin material such as tin plated plate should be thin. . In order to obtain a thin hot rolled sheet, the temperature drop (Drop) is severely generated, it is difficult to control the winding shape, not only increase the load of the hot rolling process, but also change the cooling pattern to increase the material variation, thereby reducing the cold rolling. On the other hand, if the cold reduction rate is high, the strain energy accumulated in the material increases, thereby promoting recrystallization. Therefore, in the method of the present invention, an appropriate primary cold reduction ratio range is set in consideration of hot and cold rolling properties and recrystallization behavior of steel. If the primary cold reduction rate is lower than 83%, ultra-thin hot rolled material must be produced, which not only puts a load on the hot rolling process but also worsens cold rolling. On the other hand, when the primary cold reduction rate is greater than 90%, the recrystallization temperature is lowered, but it is difficult to secure the ductility of the secondary rolled plate, so the primary cold reduction rate is preferably limited to 83 to 90%.

한편, 본 발명에 따르면 2차 냉연강판의 가공성은 1차 및 2차 압하율의 조합에 의해 큰 영향을 받는 것으로 조사되었다. 1차 및 2차 냉간 압하율의 합, (CR1+0.9xCR2)이 95%보다 낮으면 가공 경화량이 적어 목표 강도 및 내압특성을 확보할 수 없다. 반면에 (CR1+0.9 x CR2)가 120%를 초과하면 가공 경화량은 포화치를 나타내는데 반하여 연성이 급격히 감소하여 소재의 넥킹 가공성 확보가 곤란할 뿐만 아니라 2차 압연성을 떨어뜨리는 요인으로 작용하므로 (CR1+0.9xCR2)의 범위는 95~120%로 한정하는 것이 바람직하다.
On the other hand, according to the present invention, the workability of the secondary cold rolled steel sheet was investigated to be greatly affected by the combination of the primary and secondary reduction ratio. If the sum of the primary and secondary cold reduction rates, (CR 1 + 0.9xCR 2 ) is lower than 95%, the amount of work hardening is small and the target strength and pressure resistance characteristics cannot be obtained. On the other hand, if (CR 1 +0.9 x CR 2 ) exceeds 120%, the amount of work hardening indicates a saturation value, whereas the ductility decreases rapidly, which makes it difficult to secure necking workability of the material and also acts as a factor that lowers the secondary rolling property. It is preferable to limit the range of (CR 1 + 0.9xCR 2 ) to 95 to 120%.

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

[실시예]EXAMPLE

표 1과 같이 조성되는 알루미늄 킬드강을 오스테나이트역에서 재가열하여 표 1의 조건으로 열간압연하고, 초당 20℃의 냉각속도로 표 2의 권취 온도 부근까지 냉각한 다음, 냉간압연하였다. The aluminum-kilted steel formed as shown in Table 1 was reheated in an austenite zone, hot rolled under the conditions of Table 1, cooled to around the winding temperature of Table 2 at a cooling rate of 20 ° C per second, and then cold rolled.                     

구분division 강종Steel grade 화 학 성 분 (중량 %)Chemical content (% by weight) 마무리 열연온도 (℃)Finish Hot Rolling Temperature (℃) CC MnMn SS AlAl NN TiTi BB Ti*/C 원자비Ti * / C atomic ratio B/N 중량비B / N weight ratio 발명강Invention steel A1A1 0.00250.0025 0.350.35 0.0090.009 0.0540.054 0.00250.0025 0.0130.013 0.00130.0013 -0.907-0.907 0.5200.520 920920 A2A2 0.00230.0023 0.490.49 0.0080.008 0.0460.046 0.00190.0019 0.0170.017 0.00090.0009 -0.165-0.165 0.4740.474 918918 A3A3 0.00280.0028 0.380.38 0.0120.012 0.0610.061 0.00270.0027 0.0150.015 0.00150.0015 -0.559-0.559 0.5560.556 925925 비교강Comparative steel A4A4 0.00840.0084 0.210.21 0.0110.011 0.0340.034 0.00350.0035 0.0190.019 0.00020.0002 -0.283-0.283 0.0380.038 920920 A5A5 0.03600.0360 0.250.25 0.0080.008 0.0420.042 0.00480.0048 -- 0.00150.0015 00 0.3120.312 893893 A6A6 0.00290.0029 1.251.25 0.0120.012 0.1200.120 0.00460.0046 0.0370.037 0.00180.0018 0.2790.279 0.3910.391 886886 A7A7 0.00210.0021 0.380.38 0.0110.011 0.0290.029 0.00240.0024 0.0420.042 -- 1.1581.158 00 915915

냉간압연판의 제조조건에 따른 특성은 표 2에 나타내었는데, 평기기준은 다음과 같다. The characteristics of the cold rolled sheet according to the manufacturing conditions are shown in Table 2, and the standard criteria are as follows.

#1)은 냉간압연특성# 1) cold rolling characteristics

1차냉간 압하율(CR1)과 2차냉간 압하율(CR2)를 다음의 식(CR1+0.9×CR2 )으로 계산한 값으로, 그 계산치를 ()에 기재하는 한편, 그 계산치가 95~115를 만족하면 ○(합격), 벗어나면 ×(불합격)으로 표기하였다.
The primary cold reduction rate (CR 1 ) and the secondary cold reduction rate (CR 2 ) are values calculated by the following equation (CR 1 + 0.9 × CR 2 ). When it satisfies 95-115, it is marked as ○ (pass), and when it is out, it is expressed as x (fail).

#2)는 목표조질도# 2) target quality

2차압연 냉연강판의 재질이 항복강도 49~60kgf/mm2을 만족하면 ○(합격), 벗어나면 ×(불합격)으로 표기하였다.
If the material of the secondary rolled cold rolled steel satisfies the yield strength of 49 ~ 60kgf / mm 2 , it is marked as ○ (pass), and if not, × (fail).

#3)은 저항용접성# 3) resistance to welding

용접모사실험에 의해 용접 열영향부의 미세 조직 크기가 모재에 비하여 10㎛ 이상 차이가 나면 ×(불합격), 10㎛보다 조직 차이가 적으면 ○(합격)로 표기하였다.
When the microstructure size of the weld heat affected zone differed by 10 µm or more from the base material by the welding simulation test, the result was × (failed) and ○ (passed) when the tissue difference was smaller than 10 µm.

#4)는 소둔 통판성# 4) annealed mailing

재결정온도 740℃를 기준으로 ○(합격, 재결정온도 740℃이하), ×(불합격, 재결정온도 740℃초과)로 표기하였다.
Based on the recrystallization temperature of 740 ° C, it is indicated as ○ (pass, recrystallization temperature below 740 ° C), × (failure, recrystallization temperature exceeding 740 ° C).

#5) 압연성# 5) rollability

냉간압하율에 따른 항복강도의 변화에서 구한 변형저항값으로 평가하고, 1차 냉연시 적용 압하율에서 변형 저항강도가 90~110kgf/mm2 범위이면 ○(합격), 벗어나면 ×(불합격)으로 표기하였다.
Evaluate the deformation resistance obtained from the change in yield strength according to the cold reduction rate, and if the deformation resistance strength in the primary cold rolling is 90 ~ 110kgf / mm 2 range, ○ (pass), if not, × (fail) Notation is shown.

#6) 넥킹(Necking) 가공성# 6) Necking processability

2차 압연판을 소부(Baking)후 지름 50mm의 Cone으로 압축가공시 35mm 깊이까지 크랙이 발생하지 않으면 ○(합격), 균열이 발생하는 경우에는 ×(불합격)으로 표기하였다. After baking, the secondary rolled sheet was marked with a cone of 50 mm in diameter, and if cracking did not occur to a depth of 35 mm during compression processing, ○ (pass) and crack (x) failed.                     

구분division 강종Steel grade 권취 온도 (℃)Coiling temperature (℃) 1차냉간 압하율 (CR1)Primary cold reduction rate (CR 1 ) CR1+ 0.9xCR2 #1) CR 1 + 0.9xCR 2 # 1) 목표 조질도#2) Goal Quality # 2) 저항 용접성#3) Resistance weldability # 3) 소둔 통판성#4) Annealed Mail # 4) 압연성#5) Rollability # 5) 넥킹 가공성#6) Necking processability # 6) 비고Remarks ①① A1A1 520520 8686 O (115)O (115) OO OO XX XX OO 비교재Comparative material ②② A1A1 640640 8686 O (115)O (115) OO OO OO OO OO 발명강Invention steel ③③ A1A1 740740 8686 O (115)O (115) XX XX OO OO XX 비교재Comparative material ④④ A2A2 660660 8585 X (90)X (90) XX OO OO XX OO 비교재Comparative material ⑤⑤ A2A2 660660 8787 O (110)O (110) OO OO OO OO OO 발명강Invention steel ⑥⑥ A2A2 660660 9595 O (110)O (110) XX OO XX XX OO 비교재Comparative material ⑦⑦ A3A3 640640 8484 O (105)O (105) OO OO OO OO OO 발명강Invention steel ⑧⑧ A3A3 640640 8888 X (128)X (128) XX OO OO XX XX 비교재Comparative material ⑨⑨ A4A4 450450 7070 X (90)X (90) XX XX OO XX XX 비교강Comparative steel ⑩⑩ A4A4 620620 8585 O (113)O (113) OO XX OO OO XX 비교강Comparative steel ⑪⑪ A5A5 640640 8686 O (115)O (115) XX OO OO OO XX 비교강Comparative steel ⑫⑫ A6A6 620620 8888 O (100)O (100) OO OO XX XX OO 비교강Comparative steel ⑬⑬ A7A7 660660 8484 X (94)X (94) XX XX XX XX XX 비교강Comparative steel ⑭⑭ A7A7 660660 8989 O (110)O (110) OO XX XX OO XX 비교강Comparative steel

C, B, Ti 등의 조성 및 유효Ti/C 원자비, B/N 중량비가 발명강의 성분 범위를 만족하는 강을 이용하여 열연 권취온도가 본 발명의 제조 범위인 600~700℃를 벗어나는 영역에서 제조된 비교재 ①(권취온도 520℃)은 석출물의 분포 및 크기가 미세화되어 극박재의 통판성을 확보하기 곤란하였을 뿐만 아니라 열연강판의 폭 방향으로의 재질 편차가 심하게 발생하여 압연성이 극히 나빠지는 문제점을 나타내어 작업성을 확보하기 어려웠다.
In the region where the hot rolling temperature is outside the manufacturing range of the present invention 600 ~ 700 ℃ using a steel such as C, B, Ti composition, effective Ti / C atomic ratio, B / N weight ratio satisfies the component range of the invention steel The manufactured comparative material ① (coiling temperature 520 ℃) has a difficult distribution and size of precipitates, which makes it difficult to secure the ultra-thin sheet flowability, and the material variation in the width direction of the hot rolled steel sheet is severe, resulting in extremely poor rollability. Showed problems and it was difficult to secure workability.

반면에 권취온도가 740℃인 비교재 ③의 경우에는 냉간압연성 및 소둔 통판성은 양호하였지만 표면 스케일(Scale)층의 박리가 곤란하여 표면 결함을 유발하는 문제점 이 있었다. 또한 결정립이 조대화됨에 따라 목표 조질도를 확보하기 곤란하였으며, 질화물의 석출이 촉진되어 저항 용접시 용접 열영향부 조직이 이상 성장하는 문제점을 나타내어 넥킹 가공시 균열의 원인으로 작용하였다.
On the other hand, in the case of the comparative material ③ having a coiling temperature of 740 ° C., the cold rolling property and the annealing plateability were good, but there was a problem of causing surface defects due to difficulty in peeling the surface scale layer. In addition, as the grain size was coarsened, it was difficult to secure the target quality, and the deposition of nitride was promoted, resulting in abnormal growth of the weld heat affected zone during resistance welding, which acted as a cause of cracking during necking.

또한, 1차 압하율은 본 발명의 관리범위를 만족하지만 1차 및 2차 냉간압하율의 합이 90%로 낮은 경우(비교재 ④)에는 목표 재질을 확보할 수 없을 뿐만 아니라 2차 압연시 미끄럼(Slip)이 발생하여 2차 압연판의 표면에 결함이 발생하는 문제점이 발생하여 작업성을 저하시키는 문제점을 나타내었다.
In addition, although the primary reduction ratio satisfies the management scope of the present invention, when the sum of primary and secondary cold reduction ratios is low as 90% (comparative material ④), not only the target material can be secured but also when the secondary rolling is performed. Slip occurred and a problem that a defect occurs on the surface of the secondary rolled plate has been shown to reduce the workability.

한편, 1차 냉간압하율이 95%로 높은 경우(비교재 ⑥) 및 (CR1+CR2)가 본 발명의 범위를 벗어나는 비교재 ⑧의 경우 목표로 하는 조질도 범위를 확보할 수 없었으며, 또한 압연성을 악화시키는 요인으로 작용하였다.
On the other hand, when the primary cold reduction rate is high as 95% (Comparative Material ⑥) and the comparative material ⑧ (CR 1 + CR 2 ) is outside the scope of the present invention, the target quality range could not be secured. Also, it acted as a factor deteriorating rollability.

또한 비교재 ⑥의 경우 연속소둔 공정에서의 통판성도 얻을수 없었으며, 비교재 ⑧은 넥킹가공시 연성 부족에 의해 가공 균열이 발생하였다.
In addition, in case of the comparative material ⑥, the plateability in the continuous annealing process was not obtained, and the comparative material ⑧ caused the processing crack due to the lack of ductility during the necking process.

한편, 본 발명강의 화학 조성에 비하여 C, N의 첨가량이 많고 Mn, B의 첨가량이 적음에 따라 B/N의 중량비가 본 발명의 조건을 만족하지 못하는 비교강 A4를 이용하여 본 발명의 권취 및 1, 2차 냉간압연 제조 범위를 벗어나는 영역(비교재 ⑨) 및 제조 영역은 만족하는 범위(비교재 ⑩)에서 제조한 2차 압연강판의 경우 고용으로 존재하는 B양이 적음에 따라 저항 용접시 용접 열영향부 조직의 이상 성장이 발생하여 저항 용접성을 확보할 수 없었으며, 또한 넥킹 가공시 용접 열영향부 주위에서 균열이 발생하는 문제점이 있었다. 또한 비교재 ⑨의 경우 1차 냉간 압하율이 낮음에 따라 2차 압연후에도 목표로 하는 항복강도 49~60kgf/mm2의 재질을 확보할 수 없었다.
On the other hand, as the addition amount of C, N and the amount of addition of Mn, B is small compared to the chemical composition of the present invention, the weight ratio of B / N does not satisfy the conditions of the present invention. The area outside the manufacturing range of the first and second cold rolled steels (the comparative material ⑨) and the manufacturing area should be less than the amount of B present in solid solution in the case of the secondary rolled steel sheet manufactured in the satisfactory range (the comparative material ⑩). Abnormal growth of the weld heat affected zone occurred, so that resistance weldability could not be secured, and cracking occurred around the weld heat affected zone during the necking process. In addition, the comparative material ⑨ could not secure the target yield strength of 49 ~ 60kgf / mm 2 even after the second rolling due to the low primary cold reduction rate.

또한 C, N 첨가량이 발명의 성분 범위를 벗어나고 Ti를 첨가하지 않음에 따라 유효Ti/C 원자비가 0인 비교강 A5를 이용한 경우(비교재 ⑪)에도 저항 용접성의 확보는 가능하였지만, 시효 현상이 발생하여 소재의 재질 편차를 일으키는 요인으로 작용하였을 뿐만 아니라 변형시효에 의한 재질 경화가 발생하여 목표 조질도를 벗어나는 강도 수준을 나타내었다. 또한 이와 같은 변형시효의 발생은 연성의 급격한 감소를 유발하여 2차 압연강판의 넥킹 가공성도 떨어뜨려 가공성이 요구되는 2차 압연강판의 적용 용도로 사용하기는 곤란하였다.
In addition, even when comparative steel A5 having an effective Ti / C atomic ratio of 0 was used (comparative material N) as the amount of C and N was out of the component range of the invention and no Ti was added, the resistance weldability was obtained. It not only caused the material variation of the material, but also caused the hardening of the material due to the strain aging, indicating the strength level that is beyond the target quality. In addition, the occurrence of the strain aging caused a sharp decrease in ductility, and also reduced the necking workability of the secondary rolled steel sheet, it was difficult to use the application of the secondary rolled steel sheet is required.

Mn, Al, N 및 Ti의 첨가량이 발명강의 조성에 비하여 높은 비교강 A6를 이용하여 본 발명의 냉연 등 제조 영역내에 제조한 비교재 ⑫의 경우 저항 용접성 및 목표 재질은 확보할 수 있었지만, Mn 등에 의해 소재의 편석이 심하게 발생하고 유효Ti/C 원자비가 높음에 따라 재결정 온도가 상승하여 소둔 통판성을 확보할 수 없었다. 또한 스케일 등의 결함이 발생하여 냉간압연성을 크게 저하시키는 요인으로 작용하였다.
In the case of the comparative material 한 manufactured in the manufacturing region of the cold rolled steel of the present invention using comparative steel A6, in which the amount of Mn, Al, N, and Ti was higher than that of the inventive steel, resistance weldability and target material could be secured. As a result, segregation of the material severely occurred and the effective Ti / C atomic ratio was high, so that the recrystallization temperature was increased to ensure annealing and mailing. In addition, defects such as scale occurred, which acted as a factor to greatly reduce the cold rolling.

다른 화학 성분들은 본 발명강의 성분 범위를 만족하지만 Ti, B의 첨가량 및 유효Other chemical components satisfy the component range of the present invention steel, but the amount of Ti and B added and effective

Ti/C원자비와 B/N의 중량비가 발명법의 범위를 벗어나는 비교강 A7재을 이용하여 1, 2차 냉간압하율 조건이 본 발명의 범위를 벗어나는 경우(비교재 ⑬) 및 본 발명의 제조 범위를 만족하는 조건(비교재 ⑭)에서도 저항 용접시 용접 열영향부의 조직이 현저히 조대화되어 용접부 판 파단의 요인으로 작용하여 저항 용접성이 현저히 떨어졌다. 또한 미세한 Ti계 석출물의 석출에 의해 재결정온도가 상승하여 연속소둔로에서의 통판성 확보도 곤란하였다. 이와 같은 조건으로 제조한 소재를 2차 압연후 넥킹성이 요구되는 용도로 가공하는 경우에도 목표로 하는 넥킹 가공성을 확보할 수 없었다. 특히 본 발명법의 제조조건을 벗어나는 비교재 ⑬의 목표 재질보다 낮은 항복강도를 나타내었을 뿐만 아니라 적정 압하 조건을 설정하기 곤란하여 압연성을 저하시키는 문제점도 나타내었다.
In the case where the first and second cold rolling reduction conditions deviate from the scope of the present invention using comparative steel A7 material in which the weight ratio of Ti / C atomic ratio and B / N is outside the scope of the invention method (Comparative material iii) and the preparation of the present invention Even under the condition that meets the range (comparative material ⑭), the structure of the weld heat affected zone was significantly coarse during resistance welding, which acted as a factor of fracture of the weld plate, and the resistance weldability was remarkably decreased. In addition, the recrystallization temperature was increased due to the precipitation of fine Ti precipitates, and it was also difficult to secure the flow through the continuous annealing furnace. Even when the raw material manufactured under such conditions was processed for the use requiring necking property after the secondary rolling, the target necking workability could not be secured. In particular, not only the yield strength was lower than that of the target material of the comparative material 는 deviating from the manufacturing conditions of the present invention method, but it was also difficult to set the appropriate reduction conditions, which also showed a problem of lowering the rollability.

한편, 본 발명강의 성분 범위와 제조조건을 만족하는 발명강 ②, ⑤ 및 ⑦들은 저항용접시 용접 열영향부 미세조직의 결정립 성장을 억제함으로써 저항 용접성이 우수하였을 뿐만 아니라 2차 압연강판의 항복강도도 49~60kgf/mm2의 범위를 만족하여 목표 조질도를 얻을 수 있었다. 또한, 열처리 공정에서도 재결정을 740℃ 이하에서 완료되어 극박재의 소둔로내 통판성을 확보할 수 있었다. 이를 통해 본 발명에서 달성하고자 하였던 저항 용접성 및 넥킹 가공성이 우수한 2차 압연 강판을 제조할 수 있었다.
On the other hand, the invention steels ②, ⑤ and ⑦ satisfying the component range and manufacturing conditions of the present invention steel not only had excellent resistance weldability by inhibiting grain growth of the microstructure of the weld heat affected zone during resistance welding, but also yield strength of the secondary rolled steel sheet. The target quality was obtained by satisfying the range of FIGS. 49 to 60 kgf / mm 2 . In addition, in the heat treatment step, recrystallization was completed at 740 ° C. or lower to ensure the sheet-passing property in the annealing furnace of the ultrathin material. Through this, it was possible to manufacture a secondary rolled steel sheet excellent in resistance weldability and necking workability to be achieved in the present invention.

이상 결과에서 알 수 있듯이, 본 발명의 성분 관리 범위 및 제조 범위를 만족하는 발명강의 경우 모두 우수한 저항 용접성, 소둔 통판성을 확보함과 아울러 목표 강도 및 넥킹 가공성을 얻을 수 있었다. 반면, 본 발명의 성분 관리 범위를 벗어나거나 또는 제조 범위를 벗어나는 비교재들은 목표로 하는 특성을 만족하지 못하거나 넥킹 가공시 파단과 같은 문제를 일으켜 가공성이 요구되는 용도에 적용되는 2차 압연 강판으로 적용하기 곤란하였다.
As can be seen from the above results, in the case of the invention steel which satisfies the component management range and production range of the present invention, both excellent resistance weldability and annealing and sheeting were obtained, and target strength and necking workability were obtained. On the other hand, the comparative materials that fall outside the scope of ingredient control or manufacture of the present invention are secondary rolled steel sheets that are applied to applications in which workability is not required by satisfying target characteristics or causing problems such as breakage during necking processing. It was difficult to apply.

상술한 바와 같이, 본 발명에서는 2차 압연강판의 저항 용접성, 압연성 및 소둔 특성 등을 개선함과 아울러 가공용 소재로써 적용할 수 있을 정도의 넥킹 가공성을 확보할 수 있고, 특히, 연속소둔 공정을 경유하면서도 가공성 및 용접 특성이 우수하므로 이들 특성이 요구되는 용도에 사용하면 가공 단계에서의 균열 발생을 감소시킬 수 있다. 또한, 제품의 안정적인 작업성 확보가 가능하므로 제품의 재질 편차 발생을 감소시키고 이를 통하여 두께가 얇은 극박용 소재를 제조하는 경우에 제조 원가 절감 측면에서도 효과적이다.
As described above, in the present invention, while improving the resistance weldability, rolling properties and annealing characteristics of the secondary rolled steel sheet, it is possible to secure the necking workability that can be applied as a work material, in particular, continuous annealing process It is excellent in workability and welding properties, but it can reduce the incidence of cracking at the machining stage when used for applications requiring these properties. In addition, it is possible to secure stable workability of the product, thereby reducing the occurrence of material deviation of the product through this, it is effective in reducing the manufacturing cost when manufacturing the ultra-thin material through the thickness.

Claims (1)

중량%로, 탄소(C):0.003%이하, 망간(Mn):0.3~0.6%, 황(S):0.015%이하, 알루미늄(Al):0.04~0.09%, 질소(N):0.003% 이하, 티타늄(Ti):0.01~0.02%, 보론 :0.0005~0.002%, 나머지 기타 불가피한 불순물과 Fe로 조성되고, Ti*/C(%):-0.95~-0.15[단, Ti*=Ti(%)-(48/32)S(%)-(48/14)N(%)], B/N 중량비:0.45~0.6를 만족하는 알루미늄 킬드강을 오스테나이트 영역에서 균질화 처리하여 910~930℃의 마무리압연조건으로 열간압연하고, 600~700℃에서 권취한 다음, 1차 냉간 압하율(CR1)과 2차 냉간압하율(CR2)이 다음의 조건, 83≤CR1≤90, 95≤(CR1+0.9×CR2 )≤120으로 냉간압연하는 것을 포함하여 이루어지는 가공성이 우수한 2차 압연 냉연강판의 제조방법. By weight%, carbon (C): 0.003% or less, manganese (Mn): 0.3-0.6%, sulfur (S): 0.015% or less, aluminum (Al): 0.04-0.09%, nitrogen (N): 0.003% or less , Titanium (Ti): 0.01 ~ 0.02%, boron: 0.0005 ~ 0.002%, and other remaining unavoidable impurities and Fe, Ti * / C (%):-0.95 ~ -0.15 [However, Ti * = Ti (% )-(48/32) S (%)-(48/14) N (%)], and B / N weight ratio: 0.45 to 0.6 aluminum homogenized steel in the austenitic region and homogenized in 910 ~ 930 ℃ Hot-rolled under finish rolling conditions, wound at 600 to 700 ° C, and then the primary cold reduction rate (CR 1 ) and the secondary cold reduction rate (CR 2 ) are the following conditions: 83≤CR 1 ≤90, 95≤ A method for producing a secondary rolled cold rolled steel sheet having excellent workability, including cold rolling at (CR 1 + 0.9 × CR 2 ) ≦ 120.
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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102794301A (en) * 2012-08-03 2012-11-28 莱芜市泰山冷轧板有限公司 Manufacture method of cold-rolled electrolytic tin substrate

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH02163346A (en) * 1988-12-15 1990-06-22 Nisshin Steel Co Ltd Hot dip galvanized cold rolled high-tensile steel sheet excellent in press formability and its production
JPH08283908A (en) * 1995-04-17 1996-10-29 Nippon Steel Corp Hot dip galvanized dead-soft steel sheet excellent in fatigue characteristic and its production
JP2001316727A (en) 2000-02-29 2001-11-16 Nkk Corp Method for manufacturing cold rolled steel sheet excellent in processability and having reduced anisotropy

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH02163346A (en) * 1988-12-15 1990-06-22 Nisshin Steel Co Ltd Hot dip galvanized cold rolled high-tensile steel sheet excellent in press formability and its production
JPH08283908A (en) * 1995-04-17 1996-10-29 Nippon Steel Corp Hot dip galvanized dead-soft steel sheet excellent in fatigue characteristic and its production
JP2001316727A (en) 2000-02-29 2001-11-16 Nkk Corp Method for manufacturing cold rolled steel sheet excellent in processability and having reduced anisotropy

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102794301A (en) * 2012-08-03 2012-11-28 莱芜市泰山冷轧板有限公司 Manufacture method of cold-rolled electrolytic tin substrate

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