KR100711463B1 - Method for manufacturing high strength cold rolled steel sheet having low yield strength - Google Patents

Method for manufacturing high strength cold rolled steel sheet having low yield strength Download PDF

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KR100711463B1
KR100711463B1 KR1020050117774A KR20050117774A KR100711463B1 KR 100711463 B1 KR100711463 B1 KR 100711463B1 KR 1020050117774 A KR1020050117774 A KR 1020050117774A KR 20050117774 A KR20050117774 A KR 20050117774A KR 100711463 B1 KR100711463 B1 KR 100711463B1
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steel sheet
rolled steel
yield strength
cold rolled
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김영규
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주식회사 포스코
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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
    • C22C38/004—Very low carbon steels, i.e. having a carbon content of less than 0,01%
    • 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
    • C22C38/02—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
    • 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
    • C22C38/16—Ferrous alloys, e.g. steel alloys containing copper

Abstract

두께 1.0mm이상의 냉연강판으로 350MPa급의 인장강도를 가지면서 235MPa이하의 항복강도를 갖는 냉연강판이 제공된다.Cold rolled steel sheet having a thickness of 1.0mm or more is provided with a cold rolled steel sheet having a tensile strength of 350MPa and a yield strength of 235MPa or less.

이 냉연강판의 제조방법은, 중량%로, C:0.0025%이하, Mn: 0.003-0.15%, Si：0.06-0.1%, P： 0.03-0.04%, S： 0.006-0.012%, Sol-Al：0.02-0.05%, Cu：0.07-0.12%, Mo:0.07-0.11%, B:0.0002-0.001%, Nb:0.005-0.015%를 포함하고, 나머지 Fe 및 기타 불가피한 불순물로 조성되는 강슬라브를 열간압연하고 권취한 다음, 두께 1.0mm이상의 두께로 냉간압연한 후 820~840℃에서 소둔한 다음, 0.5-0.7%의 압하율로 조질압연하는 것이다. The manufacturing method of this cold-rolled steel sheet is weight%, C: 0.0025% or less, Mn: 0.003-0.15%, Si: 0.06-0.1%, P: 0.03-0.04%, S: 0.006-0.012%, Sol-Al: Hot-rolled steel slab containing 0.02-0.05%, Cu: 0.07-0.12%, Mo: 0.07-0.11%, B: 0.0002-0.001%, Nb: 0.005-0.015% and composed of the remaining Fe and other unavoidable impurities After winding, cold rolling to a thickness of 1.0 mm or more, followed by annealing at 820 to 840 ° C., followed by temper rolling at a reduction ratio of 0.5-0.7%.

고강도, 항복강도, 소둔온도, 조질압연, Nb High strength, yield strength, annealing temperature, temper rolling, Nb

Description

항복강도가 낮은 고강도 냉연강판의 제조방법{METHOD FOR MANUFACTURING HIGH STRENGTH COLD ROLLED STEEL SHEET HAVING LOW YIELD STRENGTH}Manufacturing method of high strength cold rolled steel sheet with low yield strength {METHOD FOR MANUFACTURING HIGH STRENGTH COLD ROLLED STEEL SHEET HAVING LOW YIELD STRENGTH}

도 1은 Nb과 P의 함량에 따른 항복강도의 변화를 나타내는 그래프이다.1 is a graph showing the change in yield strength according to the content of Nb and P.

도 2는 소둔온도에 따른 항복강도의 변화를 나타내는 그래프이다.2 is a graph showing the change in yield strength according to the annealing temperature.

도 3은 조질압연의 압하율에 따른 항복강도의 변화를 나타내는 그래프이다. 3 is a graph showing the change in yield strength according to the rolling reduction ratio of temper rolling.

본 발명은 자동차 소재로 사용되는 고강도 냉연강판의 제조방법에 관한 것이다. 보다 상세하게는 두께 1.0mm이상의 냉연강판으로 350MPa급의 인장강도를 가지면서 235MPa이하의 항복강도를 갖는 냉연강판의 제조방법에 관한 것이다. The present invention relates to a method for producing a high strength cold rolled steel sheet used as a vehicle material. More specifically, the present invention relates to a method for manufacturing a cold rolled steel sheet having a yield strength of less than 235 MPa while having a tensile strength of 350 MPa with a cold rolled steel sheet having a thickness of 1.0 mm or more.

지구환경보전을 위한 과제로서 연비규제가 강화되고, 이에 대응한 자동차의 연비개선의 대책으로서 자동차경량화를 도모하고 있다. 자동차 경량화 대책의 하나로서 강판의 고강도화에 의한 자동차 소재의 무게감소가 효과적이다. As a task for the preservation of the global environment, fuel economy regulations have been strengthened, and automobiles have been designed to reduce the weight of automobiles as a countermeasure to improve the fuel efficiency of automobiles. As one of measures to reduce the weight of automobiles, weight reduction of automobile materials is effective by increasing the strength of steel sheet.

고강도 냉연강판에서도 350MPa급 강판이 많이 사용되고 있다. 350MPa grade steel sheet is also used in high strength cold rolled steel sheet.

350MPa급 고강도 냉연강판에서는 가공성의 개선을 위해 항복강도를 낮추는 것이 요구되고 있다. 인장강도와 항복강도는 비례하므로, 인장강도는 높이면서 항복강도를 낮추는 것은 어려운 문제이다. 보다 낮은 항복강도에 대한 요구는 두께가 1.0mm이상의 냉연강판의 경우가 더 크며, 그 관리기준은 235MPa이하의 수준이다. In 350MPa high strength cold rolled steel sheet, it is required to lower the yield strength in order to improve workability. Since tensile strength and yield strength are proportional, it is difficult to lower yield strength while increasing tensile strength. The demand for lower yield strength is greater for cold rolled steel sheets with thicknesses greater than 1.0 mm, with a management criterion of 235 MPa or less.

350MPa급 고강도 냉연강판으로는 중량%로, C:0.0025%이하, Mn: 0.003-0.08%, Si：0.06-0.1%, P： 0.04-0.05%, S： 0.006-0.012%, Sol-Al：0.02-0.05%, Cu：0.07-0.12%, Mo:0.07-0.11%, B:0.0002-0.001%, Nb:0.01-0.02%를 포함하고, 나머지 Fe 및 기타 불가피한 불순물로 조성되는 성분계가 알려져 있다. 이 냉연강판은 800~820℃에서 소둔한 다음, 0.7-0.9%의 압하율로 조질압연하여 생산되고 있다. 그런데, 이 고강도 냉연강판은 두께 1mm이상으로 생산되는 경우에 약 57% 정도가 235MPa이하의 항복강도 요구조건을 충족하지 못하고 있는 실정이다. 350MPa grade high strength cold rolled steel sheet with weight%, C: 0.0025% or less, Mn: 0.003-0.08%, Si: 0.06-0.1%, P: 0.04-0.05%, S: 0.006-0.012%, Sol-Al: 0.02 A component system comprising -0.05%, Cu: 0.07-0.12%, Mo: 0.07-0.11%, B: 0.0002-0.001%, Nb: 0.01-0.02%, and composed of the remaining Fe and other unavoidable impurities is known. This cold rolled steel sheet is produced by annealing at 800-820 ° C. and then temper rolling at a reduction ratio of 0.7-0.9%. However, when the high strength cold rolled steel sheet is produced with a thickness of 1 mm or more, about 57% does not meet the yield strength requirement of 235 MPa or less.

본 발명에서는 두께 1.0mm이상으로 인장강도가 350MPa급이고 항복강도가 235MPa이하를 만족하는 냉연강판의 제조방법을 제공하는데, 그 목적이 있다. It is an object of the present invention to provide a method for manufacturing a cold rolled steel sheet having a tensile strength of 350 MPa class and a yield strength of 235 MPa or less with a thickness of 1.0 mm or more.

상기 목적을 달성하기 위한 본 발명의 고강도 냉연강판의 제조방법은, Method for producing a high strength cold rolled steel sheet of the present invention for achieving the above object,

중량%로, C:0.0025%이하, Mn: 0.003-0.15%, Si：0.06-0.1%, P： 0.03-0.04%, S： 0.006-0.012%, Sol-Al：0.02-0.05%, Cu：0.07-0.12%, Mo:0.07-0.11%, B:0.0002-0.001%, Nb:0.005-0.015%를 포함하고, 나머지 Fe 및 기타 불가피한 불순물로 조성되는 강슬라브를 열간압연하고 권취한 다음, 두께 1.0mm이상의 두께로 냉간압연한 후 820~840℃에서 소둔한 다음, 0.5-0.7%의 압하율로 조질압연하는 것이다. By weight%, C: 0.0025% or less, Mn: 0.003-0.15%, Si: 0.06-0.1%, P: 0.03-0.04%, S: 0.006-0.012%, Sol-Al: 0.02-0.05%, Cu: 0.07 Hot-rolled and wound steel slab containing -0.12%, Mo: 0.07-0.11%, B: 0.0002-0.001%, Nb: 0.005-0.015%, and composed of the remaining Fe and other unavoidable impurities, and then thickness 1.0mm After cold rolling to the above thickness, it is annealed at 820 ~ 840 ℃, and then temper rolling at a reduction rate of 0.5-0.7%.

상기한 제조방법에서 권취는 610-630℃의 온도에서 행하는 것이 바람직하다. 본 발명에서 불가피한 불순물로서 Ti 또는 N이 함유되는 경우에 이들의 관리범위는 Ti의 경우 0.003%이하, N의 경우 0.003%이하로 하는 것이 바람직하다. It is preferable to wind up at the temperature of 610-630 degreeC in the said manufacturing method. When Ti or N is contained as an unavoidable impurity in the present invention, their management range is preferably 0.003% or less for Ti and 0.003% or less for N.

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

본 발명은 항복강도에 영향을 미치는 인자에 대한 강의 성분과 제조조건에 대한 야금학적인 검토를 통해 완성된 것이다. The present invention has been completed through metallurgical examination of the steel composition and manufacturing conditions for the factors affecting the yield strength.

본 발명에 따르면 350MPa급 고강도 냉연강판을 두께 1mm이상으로 할 때, 항복강도에 영향을 미치는 핵심인자는 성분에서는 Nb과 P의 함량이며, 제조조건에서는 소둔온도와 조질압연에서의 압하율이다.According to the present invention, when the 350MPa class high strength cold rolled steel sheet is 1 mm or more in thickness, the key factors affecting the yield strength are Nb and P in the component, and the annealing temperature and the rolling reduction in temper rolling in the manufacturing conditions.

도 1에는 Nb와 P의 함량이 항복강도에 미치는 영향을 나타낸 것이다. 도 1에 따르면 Nb의 함량이 0.015%이하의 범위이고, P의 함량이 0.04%이하의 범위에서는 두께 1mm이상에서 항복강도 235MPa이하를 만족한다.Figure 1 shows the effect of the content of Nb and P on the yield strength. According to Figure 1, the content of Nb is less than 0.015%, and the content of P is less than 0.04%, the yield strength of less than 1mm satisfies less than 235MPa.

도 2에는 소둔온도에 따른 항복강도를 나타낸 것으로, 두께 1mm이상재에서는 항복강도가 800℃이상 보다 바람직하게는 820℃이상에서 안정적으로 항복강도 235MPa이 하를 만족한다.Figure 2 shows the yield strength according to the annealing temperature, in the material of 1mm or more thickness, the yield strength satisfies the yield strength 235MPa less than 800 ℃ more preferably more than 820 ℃.

도 3은 조질압연에서의 압하율에 따른 항복강도의 영향을 나타낸 것으로, 압하율 0.5%이상에서는 안정적으로 항복강도 235MPa이하를 만족한다.Figure 3 shows the effect of the yield strength according to the reduction ratio in the temper rolling, and satisfies the yield strength 235MPa or less stably at 0.5% or more reduction.

이러한 관점으로 완성된 본 발명에 대해 구체적으로 설명한다. The present invention completed in this respect will be described in detail.

탄소(C)의 함량은 0.0025중량%(이하, 간단히 %라 표기함)가 바람직하다.The content of carbon (C) is preferably 0.0025% by weight (hereinafter simply referred to as%).

C는 강의 중요한 기본 성분의 하나로, 그 함량이 0.002%를 초과하면 가공성이 저하하므로 0.0025%이하로 관리하는 것이 바람직하다. C의 함량이 0.0005%이하로 낮으면 강도가 저하되므로 C의 함량은 0.0005-0.0025%가 가장 바람직하다. C is one of the important basic constituents of steel. If the content exceeds 0.002%, the workability is lowered. If the content of C is less than 0.0005%, the strength is lowered, so the content of C is most preferably 0.0005-0.0025%.

망간(Mn)의 함량은 0.003-0.15%가 바람직하다.The content of manganese (Mn) is preferably 0.003-0.15%.

Mn은 고용강화에 의해 강도를 확보하는 원소로서 이를 위해 0.003%이상 함유되는 것이 바람직하다. Mn의 함량이 0.15%를 초과하면 가공성이 저하될 우려가 있으므로 0.15%이하로 관리하는 것이 바람직하다. Mn is an element that secures strength by solid solution strengthening, and it is preferable to contain Mn by 0.003% or more. If the content of Mn exceeds 0.15%, the workability may be lowered. Therefore, it is preferable to control it to 0.15% or less.

규소(Si)의 함량은 0.06-0.1%가 바람직하다.The content of silicon (Si) is preferably 0.06-0.1%.

Si는 고용강화에 의해 강도를 확보하는 원소로서 이를 위해 0.06%이상 함유되는 것이 바람직하다. Si의 함량이 0.1%를 초과하면 가공성이 저하될 우려가 있으므로 0.1%이하로 관리하는 것이 바람직하다. Si is an element which secures strength by solid solution strengthening, and it is preferable to contain Si at least 0.06%. If the content of Si exceeds 0.1%, the workability may be lowered, so it is preferable to manage it to 0.1% or less.

인(P)의 함량은 0.03-0.04%가 바람직하다.The content of phosphorus (P) is preferably 0.03-0.04%.

P은 고강도화를 값싸게 달성하는 데에 유효한 원소로서 이를 위해 0.03%이상 첨가한다. P의 함량이 0.04%를 초과하면 목적하는 항복강도를 확보할 수 없으므로 P의 상한은 0.04%이하로 관리한다. P is an effective element for achieving high strength at low cost, and is added at least 0.03% for this. If the P content exceeds 0.04%, the desired yield strength cannot be secured. Therefore, the upper limit of P should be controlled below 0.04%.

황(S)의 함량은 0.006-0.012%로 하는 것이 바람직하다.The content of sulfur (S) is preferably 0.006-0.012%.

S는 Fe계 석출하여 석출강화효과를 발휘하는데 이를 위해서는 0.006%이상 함유되는 것이 바람직하다. S의 함량이 0.012%를 초과하면 취성이 유발되므로 0.012%이하로 관리하는 것이 바람직하다. S exhibits a precipitation strengthening effect by Fe-based precipitation, which is preferably contained in 0.006% or more. When the content of S exceeds 0.012%, brittleness is induced, so it is preferable to manage it to 0.012% or less.

알루미늄(sol-Al)의 함량은 0.02-0.05%가 바람직하다.The content of aluminum (sol-Al) is preferably 0.02-0.05%.

Al은 제강단계에서의 탈산제로서, 또한 석출강화효과를 위해 0.02%이상 함유되는 것이 바람직하다. Al의 함량이 0.05%를 초과하면 도금시 소지철 표면에 산화물의 생성을 조장할 우려가 있다.Al is preferably contained in an amount of 0.02% or more as a deoxidizer in the steelmaking step, and for the precipitation strengthening effect. If the Al content exceeds 0.05%, there is a fear that the formation of oxide on the surface of the base iron during plating.

구리(Cu)의 함량은 0.07-0.12%가 바람직하다. The content of copper (Cu) is preferably 0.07-0.12%.

Cu는 고용강화효과를 위해 0.07%이상 첨가하는 것이 바람직하다. Cu의 함량이 0.12%를 초과하면 더 이상의 효과는 없이 비용이 상승된다.Cu is preferably added at least 0.07% for solid solution strengthening effect. If the content of Cu exceeds 0.12%, the cost increases without any further effect.

몰리브덴(Mo)의 함량은 0.07~0.11%가 바람직하다.The content of molybdenum (Mo) is preferably 0.07 ~ 0.11%.

Mo는 고용강화효과를 위해 0.07%이상 첨가하는 것이 바람직하다. Mo의 함량이 0.11%를 초과하면 더 이상의 효과 진전 없이 비용이 상승된다.Mo is preferably added at least 0.07% to enhance the solid solution. If the content of Mo exceeds 0.11%, the cost rises without further effect development.

보론(B)의 함량은 0.0002-0.001%가 바람직하다.The content of boron (B) is preferably 0.0002-0.001%.

B은 고용강화효과와 내2차가공취성에 유리하게 작용하므로 0.0002%이상 첨가하는 것이 바람직하다. B의 함량이 0.001%초과의 경우에는 강의 재결정온도를 상승시킬 수 있다.B is advantageously added to the solid solution strengthening effect and secondary processing brittleness, it is preferable to add more than 0.0002%. If the B content exceeds 0.001%, the steel recrystallization temperature may be increased.

니오븀(Nb)의 함량은 0.005-0.015%가 바람직하다.The content of niobium (Nb) is preferably 0.005-0.015%.

Nb은 C와의 반응하여 NbC석출물에 의해 강도를 높이는데 이를 위해서는 0.005%이상 첨가하는 것이 바람직하다. Nb의 함량이 0.015%초과하는 경우에는 두께 1.0mm이상의 냉연강판에서는 항복강도를 높게 하므로 0.015%이하로 관리하는 것이 바람직하다. Nb is reacted with C to increase the strength by NbC precipitates, it is preferable to add more than 0.005%. If the content of Nb exceeds 0.015%, the cold rolled steel sheet having a thickness of 1.0mm or more increases the yield strength, so it is preferable to manage it to 0.015% or less.

상기와 같이 조성되는 강에는 기타 불가피한 불순물이 포함될 수 있다. 불가피한 불순물들은 통상의 관리범위로 포함되어도 무방하다. 불순물중에 Ti의 경우 0.003%이하, N의 경우 0.003%이하로 하는 것이 바람직하다. Ti가 0.003%를 초과하면 표면품질의 저하될 우려가 있다. N의 함량이 0.003%를 초과할 경우에는 가공성이 저하될 우려가 있다. The steel formed as described above may contain other unavoidable impurities. Unavoidable impurities may be included in the normal control range. Among the impurities, it is preferable to be 0.003% or less for Ti and 0.003% or less for N. If Ti exceeds 0.003%, there is a fear that the surface quality deteriorates. If the content of N exceeds 0.003%, workability may be lowered.

상기한 성분계를 만족하는 강슬라브를 냉연강판으로 제조한다. 본 발명에서는 두께 1.0mm이상의 냉연강판의 소둔온도와 조질압연에서의 압하율을 조절하여 목표로 하는 기계적성질을 확보하는 것이다. A steel slab satisfying the above component system is manufactured from a cold rolled steel sheet. In the present invention, the target mechanical properties are secured by adjusting the annealing temperature of the cold rolled steel sheet having a thickness of 1.0 mm or more and the rolling reduction rate in temper rolling.

이하에서는, 본 발명의 이해를 위해 가장 바람직한 제조조건을 구체적인 예로 들어 설명하는데, 본 발명이 여기에 한정되는 것은 아니다. In the following, the most preferable manufacturing conditions for the understanding of the present invention will be described with specific examples, but the present invention is not limited thereto.

상기와 같이 조성되는 강슬라브를 재가열하여 열간압연한다. 재가열온도는 1170-1230℃가 바람직하다. 재가열된 슬라브는 마무리압연온도 900-930℃의 조건으로 열간압연하고 610-630℃에서 권취한다. The steel slab formed as described above is reheated and hot rolled. The reheating temperature is preferably 1170-1230 ° C. The reheated slabs are hot rolled to a finish rolling temperature of 900-930 ° C and wound up at 610-630 ° C.

권취한 열연판은 두께 1.0mm이상으로 냉간압연한다.The wound hot rolled sheet is cold rolled to a thickness of 1.0mm or more.

상기에서 얻은 냉연판은 820-840℃의 온도에서 소둔한다. 소둔온도가 820℃미만에서는 결정립성장이 불충분하고 고용탄소의 석출 부족으로 항복강도가 증가한다. 소둔온도가 840℃를 초과하면 결정립의 성장으로 인장강도가 떨어질 수 있다. The cold rolled sheet obtained above is annealed at the temperature of 820-840 degreeC. If the annealing temperature is lower than 820 ℃, the grain growth is insufficient and the yield strength increases due to the lack of precipitation of dissolved carbon. If the annealing temperature exceeds 840 ℃, the tensile strength may drop due to the growth of grains.

소둔한 냉연강판은 0.5-0.7%의 압하율로 조질압연한다. 압하율이 0.7%를 초과하면 항복강도가 높아진다. 압하율이 0.5%미만이면 인장강도가 340 Mpa 이하로 떨어 지므로 고장력강의 재질을 확보하기 어렵다. Annealed cold rolled steel sheets are temper rolled at a reduction ratio of 0.5-0.7%. If the rolling reduction exceeds 0.7%, the yield strength increases. If the rolling reduction is less than 0.5%, the tensile strength drops below 340 Mpa, making it difficult to secure a material of high tensile strength steel.

본 발명에 따라 제조된 냉연강판은 350MPa급의 인장강도를 가지면서 235MPa이하의 항복강도를 갖는다. Cold rolled steel sheet manufactured according to the present invention has a tensile strength of 350MPa class and has a yield strength of 235MPa or less.

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

[실시예 1]Example 1

표 1과 표 3의 강슬라브를 1170~1230℃의 온도에서 재가열하여 마무리압연온도 900-920℃에서 열간압연하고 610-630℃에서 권취하여 열연판을 제조하였다. 이 열연판을 냉간압연하여 두께 1.3mm의 냉연판을 얻은 다음, 이 냉연판을 표 2와 표 4의 조건으로 소둔과 조질압연하였다. 제조된 냉연판의 인장강도와 항복강도를 측정하여 표 2와 표 4에 나타내었다. The steel slabs of Table 1 and Table 3 were reheated at a temperature of 1170 ~ 1230 ° C., hot rolled at a finish rolling temperature of 900-920 ° C., and wound at 610-630 ° C. to prepare hot rolled plates. The hot rolled sheet was cold rolled to obtain a cold rolled sheet having a thickness of 1.3 mm, and then the cold rolled sheet was annealed and temper rolled under the conditions of Tables 2 and 4. Tensile and yield strengths of the prepared cold rolled sheets were measured and shown in Tables 2 and 4.

Figure 112005070985569-pat00001
Figure 112005070985569-pat00001

구분division 제조조건Manufacture conditions 기계적성질Mechanical property 　 소둔 온도 Annealing temperature 조질압연의 압하율 (%)Rolling rate of temper rolling (%) 인장강도 (Mpa)Tensile Strength (Mpa) 항복강도 (Mpa)Yield strength (Mpa) 종래재1Conventional Materials 1 803803 0.710.71 376376 269269 종래재2Conventional material 2 813813 0.840.84 369369 245245 종래재3Conventional Materials 3 811811 0.740.74 372372 241241 종래재4Conventional Materials 4 811811 0.740.74 372372 239239 종래재5Conventional Materials 5 811811 0.740.74 372372 243243 종래재6Conventional Materials 6 814814 0.670.67 372372 251251 종래재7Conventional Materials 7 812812 0.670.67 360360 244244 종래재8Conventional Materials 8 816816 1.191.19 367367 269269 종래재9Conventional Materials 9 814814 0.670.67 368368 283283 종래재10Conventional Materials 10 812812 0.670.67 368368 283283 종래재11Conventional Materials 11 779779 0.530.53 357357 241241 종래재12Conventional Materials12 750750 0.330.33 361361 241241 종래재13Conventional Materials 13 812812 0.970.97 372372 283283 종래재14Conventional Material14 812812 0.970.97 372372 283283 종래재15Conventional Material15 817817 0.730.73 362362 241241 종래재16Conventional Materials 16 817817 0.730.73 353353 245245 종래재17Conventional Materials 17 814814 0.750.75 356356 248248 종래재18Conventional Materials 18 814814 0.750.75 356356 252252 종래재19Conventional materials 19 814814 0.750.75 356356 253253 종래재20Conventional 20 814814 0.770.77 354354 241241 종래재21Conventional Materials 21 814814 0.770.77 372372 241241 종래재22Conventional Materials 22 814814 0.750.75 354354 254254

Figure 112005070985569-pat00002
Figure 112005070985569-pat00002

구분division 제조조건Manufacture conditions 기계적성질Mechanical property 　 소 둔 온도 Annealing temperature 조질압연의 압하율 (%)Rolling rate of temper rolling (%) 인장강도 (Mpa)Tensile Strength (Mpa) 항복강도 (Mpa)Yield strength (Mpa) 발명재1Invention 1 826826 0.640.64 354354 219219 발명재2Invention 2 828828 0.640.64 354354 225225 발명재3Invention 3 823823 0.620.62 354354 204204 발명재4Invention 4 823823 0.640.64 354354 205205 발명재5Invention 5 823823 0.640.64 354354 205205 발명재6Invention 6 823823 0.640.64 354354 205205 발명재7Invention Material7 823823 0.640.64 372372 205205 발명재8Invention Material 8 826826 0.640.64 345345 223223 발명재9Invention Material 9 823823 0.640.64 372372 215215 발명재10Invention 10 823823 0.640.64 361361 215215 발명재11Invention 11 823823 0.640.64 361361 215215 발명재12Invention Material12 823823 0.640.64 361361 205205 발명재13Invention Material 13 824824 0.60.6 345345 213213 발명재14Invention 14 824824 0.660.66 350350 195195 발명재15Invention 15 829829 0.660.66 350350 195195 발명재16Invention 16 829829 0.640.64 350350 222222 발명재17Invention 17 824824 0.640.64 350350 222222 발명재18Invention 18 829829 0.640.64 359359 222222 발명재19Invention Material 19 829829 0.60.6 359359 222222 발명재20Invention 20 829829 0.660.66 356356 222222 발명재21Inventive Materials21 829829 0.660.66 356356 222222 발명재22Invention Material22 829829 0.640.64 365365 222222

표 1-4에 나타난 바와 같이, 본 발명의 조건을 만족하는 발명재들은 인장강도 350MPa급에서 235MPa이하의 항복강도를 갖는 것을 알 수 있다. As shown in Table 1-4, it can be seen that the invention materials satisfying the conditions of the present invention have a yield strength of 235 MPa or less in the tensile strength 350MPa class.

상술한 바와 같이, 본 발명에 의하면 두께 1mm이상으로 생산되는 경우에도 350MPa급의 인장강도를 가지면서 235MPa이하의 항복강도를 만족하여 가공성이 우수하다. As described above, according to the present invention, even when produced to a thickness of 1mm or more, it has a tensile strength of 350MPa class and satisfies the yield strength of 235MPa or less, and is excellent in workability.

Claims (3)

중량%로, C:0.0025%이하, Mn: 0.003-0.15%, Si：0.06-0.1%, P： 0.03-0.04%, S： 0.006-0.012%, Sol-Al：0.02-0.05%, Cu：0.07-0.12%, Mo:0.07-0.11%, B:0.0002-0.001%, Nb:0.005-0.015%를 포함하고, 나머지 Fe 및 기타 불가피한 불순물로 조성되는 강슬라브를 열간압연하고 권취한 다음, 두께 1.0mm이상의 두께로 냉간압연한 후 820~840℃에서 소둔한 다음, 0.5-0.7%의 압하율로 조질압연하는 것을 특징으로 하는 항복강도가 낮은 고강도 냉연강판의 제조방법.By weight%, C: 0.0025% or less, Mn: 0.003-0.15%, Si: 0.06-0.1%, P: 0.03-0.04%, S: 0.006-0.012%, Sol-Al: 0.02-0.05%, Cu: 0.07 Hot-rolled and wound steel slab containing -0.12%, Mo: 0.07-0.11%, B: 0.0002-0.001%, Nb: 0.005-0.015%, and composed of the remaining Fe and other unavoidable impurities, and then thickness 1.0mm Cold rolling to the above thickness and then annealed at 820 ~ 840 ℃, then a high strength cold rolled steel sheet having a low yield strength, characterized in that the temper rolling at a reduction rate of 0.5-0.7%. 제 1항에 있어서, 상기 권취는 610-630℃의 온도에서 행하는 것을 특징으로 하는 항복강도가 낮은 고강도 냉연강판의 제조방법. The method of manufacturing a high strength cold rolled steel sheet having a low yield strength according to claim 1, wherein the winding is performed at a temperature of 610-630 ° C. 제 1항에 있어서, 상기 강슬라브에는 Ti가 0.003%이하, N이 0.003%이하로 포함되는 것을 특징으로 하는 항복강도가 낮은 고강도 냉연강판의 제조방법. The method of manufacturing a high strength cold rolled steel sheet having low yield strength according to claim 1, wherein the steel slab contains Ti in an amount of 0.003% or less and N in an amount of 0.003% or less.
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KR20010040682A (en) * 1998-12-07 2001-05-15 야마오카 요지로 High strength cold rolled steel plate and method for producing the same

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109666875A (en) * 2019-02-22 2019-04-23 攀钢集团攀枝花钢铁研究院有限公司 Building aseismicity energy-absorbing hot continuous rolling steel band and preparation method

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