KR19980046771A - Manufacturing method of high toughness thick steel sheet with high productivity - Google Patents

Manufacturing method of high toughness thick steel sheet with high productivity Download PDF

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KR19980046771A
KR19980046771A KR1019960065175A KR19960065175A KR19980046771A KR 19980046771 A KR19980046771 A KR 19980046771A KR 1019960065175 A KR1019960065175 A KR 1019960065175A KR 19960065175 A KR19960065175 A KR 19960065175A KR 19980046771 A KR19980046771 A KR 19980046771A
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temperature
steel sheet
rolling
thick steel
cooling
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KR1019960065175A
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KR100293193B1 (en
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엄정현
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김종진
포항종합제철 주식회사
신창식
재단법인 포항산업과학연구원
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    • BPERFORMING OPERATIONS; TRANSPORTING
    • B21MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21BROLLING OF METAL
    • B21B3/00Rolling 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
    • B21B3/02Rolling special iron alloys, e.g. stainless steel
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B21MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21BROLLING OF METAL
    • B21B1/00Metal-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
    • B21B1/22Metal-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
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22CALLOYS
    • C22C38/00Ferrous alloys, e.g. steel alloys
    • C22C38/02Ferrous alloys, e.g. steel alloys containing silicon
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22CALLOYS
    • C22C38/00Ferrous alloys, e.g. steel alloys
    • C22C38/04Ferrous alloys, e.g. steel alloys containing manganese
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22CALLOYS
    • C22C38/00Ferrous alloys, e.g. steel alloys
    • C22C38/12Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22CALLOYS
    • C22C38/00Ferrous alloys, e.g. steel alloys
    • C22C38/16Ferrous alloys, e.g. steel alloys containing copper
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B21MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21BROLLING OF METAL
    • B21B2261/00Product parameters
    • B21B2261/20Temperature
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B21MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21BROLLING OF METAL
    • B21B2265/00Forming parameters
    • B21B2265/14Reduction rate

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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

본 발명은 후강판의 제조방법에 관한 것이며, 그 목적은 생산성이 우수한 고인성 후강판의 제조방법을 제공함에 있다.The present invention relates to a method for producing a thick steel sheet, and an object thereof is to provide a method for producing a high toughness thick steel sheet excellent in productivity.

상기 목적을 달성하기 위한 본 발명은 두께가 35㎜ 이상의 후강판을 제어압연 또는 가속냉각 방법으로 제조하는 방법에 있어서, 중량%로 C:0.03-0.25%, Si:0.05-0.5%, Mn:0.5-2.2%, Nb:0.005-0.1%, V:0.05-0.1%, Ti:0.001-0.05%, Cu:0.001-1.0%, Ni:0.001-1.0%, Al:0.001-0.1%, P:0.02%이하, S:0.015%이하, 나머지 Fe 및 기타 불가피하게 함유하는 불순물로 이루어진 강 슬라브를 1100-1250℃의 온도범위로 가열하여, 이 온도에서 2시간이상 유지한 후 930-1000℃의 온도범위까지 3-20℃/sec의 속도로 냉각한 다음, 누적압하량 65% 이상으로 Ac3이상의 마무리압연온도 조건으로 압연한 후, 500℃ 이상의 온도까지 5-20℃/sec의 속도로 냉각하고, 이후 공냉하는 생산성이 우수한, 고인성 후강판의 제조방법에 관한 것을 그 기술적 요지로 한다.The present invention for achieving the above object is a method for producing a thick steel sheet having a thickness of 35mm or more by controlled rolling or accelerated cooling method, by weight% C: 0.03-0.25%, Si: 0.05-0.5%, Mn: 0.5 -2.2%, Nb: 0.005-0.1%, V: 0.05-0.1%, Ti: 0.001-0.05%, Cu: 0.001-1.0%, Ni: 0.001-1.0%, Al: 0.001-0.1%, P: 0.02% Below, S: 0.015% or less, the steel slab composed of the remaining Fe and other inevitable impurities are heated to a temperature range of 1100-1250 ° C., maintained at this temperature for 2 hours or more and then to a temperature range of 930-1000 ° C. After cooling at a rate of 3-20 ° C./sec, rolling at a finish rolling temperature of Ac 3 or higher at a cumulative reduction of 65% or more, and then cooling at a rate of 5-20 ° C./sec to a temperature of 500 ° C. or higher, and then The technical gist of the manufacturing method of the high toughness thick steel sheet which is excellent in air cooling productivity is made.

Description

생산성이 우수한 고인성 후강판의 제조방법Manufacturing method of high toughness thick steel sheet with high productivity

본 발명은 두께가 35㎜ 이상의 후강판을 제어압연 또는 가속냉각 방법으로 제조하는 방법에 관한 것으로써, 보다 상세하게는 생산성이 우수한 고인성 후강판의 제조방법에 관한 것이다.The present invention relates to a method for manufacturing a thick steel sheet having a thickness of 35 mm or more by a controlled rolling or accelerated cooling method, and more particularly, to a method for producing a high toughness thick steel sheet having excellent productivity.

통상, 후강판을 압연하여 생산하는 대표적인 방법으로는 일반압연방법, 제어압연방법, 가속냉각방법 및 직접소입방법 등이 있다. 이중, 상기 일반압연방법은 강재의 재결정온도구간에서 압연을 마무리하는 것으로서, 강재의 물성 및 조직은 화학성분이나 열처리에 의해서 주로 결정되고, 압연은 단지 강판의 두께 및 형상을 결정하는데 그 목적이 있다. 또한, 상기 제어압연방법은 열간압연공정을 제어하여 입도를 미세하게 함으로써, 강의 인성 및 강도를 동시에 향상시킬 수 있는 방법으로 열가공처리(Thermo Mechanical Treatement)기술의 일종이다. 이 기술의 요체는 미재결정역의 온도를 상승시키고 석출강화효과를 가지는 Nb, V, Ti 등의 합금원소를 강재에 미량 첨가하고 미재결정역의 압연을 적절히 행함으로써 열처리 없이도 후강판의 인성 및 강도를 동시에 향상시키는 기술로 잘 알려져 있고, 각 제철소에서 실제 적용도 활발한 기술이다. 또한, 상기 가속냉각이나 직접소입기술은 상기 제어압연의 효과를 극대화하기 위하여 제어압연후 강재의 변태, 석출온도구간을 수냉하는 기술로 역시 실용화되어 적극 적용되고 있는 기술이다.In general, typical methods for rolling and producing thick steel sheets include general rolling methods, controlled rolling methods, accelerated cooling methods, and direct quenching methods. Among these, the general rolling method is to finish the rolling in the recrystallization temperature section of the steel, the properties and structure of the steel is mainly determined by the chemical composition or heat treatment, the rolling is only to determine the thickness and shape of the steel sheet. . In addition, the controlled rolling method is a kind of thermo mechanical treatment technology that can improve the toughness and strength of the steel at the same time by controlling the hot rolling process to make the grain size fine. The main idea of this technique is to increase the temperature of the unrecrystallized zone, add a small amount of alloying elements such as Nb, V, Ti, etc., which have a precipitation strengthening effect, to the steel and perform rolling of the unrecrystallized zone appropriately so that the toughness and strength of the thick steel sheet can be achieved without heat treatment. It is well known as a technology to improve the same time, the practical application in each steel mill is also active technology. In addition, the accelerated cooling or direct quenching technology is also a technology that is practically applied and actively applied as a technique of water cooling the transformation temperature and precipitation temperature section of steel after control rolling in order to maximize the effect of the control rolling.

상기 압연방법들중 여러 가지 잇점으로 제어압연방법이 보다 널리 이용되고 있는데, 상기 제어압연방법으로 압연하는 경우에는 미재결정역 누적압하율을 65-70% 이상으로 제어하여 압연하는 것이 강도 및 인성의 균형된 향상을 꽤할 수 있다는 것은 잘 알려진 공지의 사실이다.The control rolling method is more widely used due to various advantages of the rolling methods. In the case of rolling by the control rolling method, rolling with control of the unrecrystallized cumulative region reduction rate of 65-70% or more is performed according to the strength and toughness. It is well known that well-balanced improvements can be made.

종래, 20-30㎜ 정도의 두께를 가지는 후강판의 경우는 미재결정역 누적압하율을 확보하여 생산하는데 큰 문제점이 없으나, 35㎜정도 이상의 두께를 가지는 후 강판의 경우는 생산성이 떨어지는 문제가 있다. 구체적으로 설명하면, 종래 35㎜정도 이상의 두께를 가지는 후물재의 압연공정은 미재결정역에서 65-70%의 누적압하율을 확보하기 위해서, 가열로에서 슬래브 추출후 재결정역에서 압하율 30% 이하로 슬라브 두께를 200㎜ 정도로 압연한 후 900℃정도까지 공냉한 후 미재결정역 압연을 시작하였다. 이와 같이 재결정역에서 슬라브 두께를 압하하는 것과는 상관없이 미재결정압연개시 온도조건을 위해서 장시간 냉각하며 즉, 상기 공냉은 냉각속도가 0.5도/초 이하여서 생산성 저하가 극심하게 발생하게 되는 것이다.Conventionally, in the case of thick steel sheet having a thickness of about 20-30mm, there is no big problem in producing and securing the unrecrystallized cumulative reduction ratio, but in the case of a steel sheet having a thickness of about 35mm or more, productivity is inferior. . Specifically, in the conventional rolling process of thick material having a thickness of about 35 mm or more in order to ensure the cumulative reduction rate of 65-70% in the unrecrystallized zone, after the slab extraction in the heating furnace 30% or less in the recrystallization zone after extraction The furnace slab thickness was rolled to about 200 mm, followed by air cooling to about 900 ° C., and then unrecrystallized station rolling was started. As such, regardless of the slab thickness being reduced in the recrystallization zone, the cooling is performed for a long time for the unrecrystallization rolling start temperature condition, that is, the air cooling has a cooling rate of 0.5 degrees / sec or less, which leads to severe productivity degradation.

최근, 이러한 문제점을 해결하기 위해서 강 슬라브 2-3매를 동시에 압연한 후 공냉대기 시키는 방법을 쓰기도 하나 효과가 그다지 크지 않다. 또한, 일본제철소에서는 슬라브 재가열온도를 아예 900℃정도 낮게 하여 추출후 바로 미재결정역 압연을 시작하는 방법을 사용하기도 하나, 이는 슬라브 내부까지 목표온도에 도달하기가 어려워 재가열에 장시간이 소요되며, 첨가한 합금원소도 전량 재고용되지 않아 강도 특성이 저하되는 등의 문제가 있다.Recently, in order to solve such a problem, a method of air cooling air after rolling 2-3 sheets of steel slabs at the same time is used, but the effect is not so great. In addition, in Japanese steel mills, the slab reheating temperature is lowered to about 900 ° C. and the unrecrystallized rolling is started immediately after extraction. However, it is difficult to reach the target temperature to the inside of the slab, which takes a long time to reheat. There is a problem that all alloy elements are not reusable all the time and the strength characteristics are lowered.

이에, 본 발명은 상기 문제를 해결하기 위하여 안출된 것으로, 압연중의 공정제어를 통하여 인성 및 강도가 우수하며, 특히 생산성을 크게 향상시킬 수 있는 후강판의 제조방법을 제공하는데, 그 목적이 있다.Accordingly, the present invention has been made in order to solve the above problems, it is excellent in toughness and strength through the process control during rolling, and in particular, to provide a method for producing a thick steel sheet that can greatly improve the productivity, the object is .

도 1도는 본 발명의 제조공정을 나타내는 일례도Figure 1 is an example showing a manufacturing process of the present invention

상기 목적을 달성하기 위한 본 발명은 두께가 35㎜ 이상의 후강판을 제어압연 또는 가속냉각 방법으로 제조하는 방법에 있어서, 중량%로 C:0.03-0.25%, Si:0.05-0.5%, Mn:0.5-2.2%, Nb:0.005-0.1%, V:0.005-0.1%, Ti:0.001-0.05%, Cu:0.001-1.0%, Ni:0.001-1.0%, Al:0.001-0.1%, P:0.02%이하, S:0.015%이하, 나머지 Fe 및 기타 불가피하게 함유하는 불순물로 이루어진 강 슬라브를 1100-1250℃의 온도범위로 가열하여, 이 온도에서 2시간이상 유지한 후 930-1000℃의 온도범위까지 3-20℃/sec의 속도로 냉각한 다음, 압하량 65%이상으로 Ac3이상의 마무리압연온도 조건으로 압연한 후, 500℃ 이상의 온도까지 5-20℃/sec의 속도로 냉각하고, 이후 공냉하는 생산성이 우수한 고인성 후강판의 제조방법에 관한 것이다.The present invention for achieving the above object is a method for producing a thick steel sheet having a thickness of 35mm or more by controlled rolling or accelerated cooling method, by weight% C: 0.03-0.25%, Si: 0.05-0.5%, Mn: 0.5 -2.2%, Nb: 0.005-0.1%, V: 0.005-0.1%, Ti: 0.001-0.05%, Cu: 0.001-1.0%, Ni: 0.001-1.0%, Al: 0.001-0.1%, P: 0.02% Below, S: 0.015% or less, the steel slab composed of the remaining Fe and other inevitable impurities are heated to a temperature range of 1100-1250 ° C., maintained at this temperature for 2 hours or more and then to a temperature range of 930-1000 ° C. After cooling at a rate of 3-20 ° C./sec, rolling at a finish rolling temperature of Ac 3 or more at a rolling reduction of 65% or more, and then cooling at a rate of 5-20 ° C./sec to a temperature of 500 ° C. or higher, and then air-cooling It relates to a method for producing a high toughness thick steel sheet excellent in productivity.

이하, 본 발명강 성분의 수치한정이유에 대하여 설명한다.The reason for numerical limitation of the steel component of the present invention is described below.

상기 C는 강재의 강도를 확보하는 필수 기본성분이지만 다량 함유된 경우에는 인성과 용접성을 저하시키므로 0.03-0.25% 범위가 바람직하다.The C is an essential basic component to secure the strength of the steel, but when contained in a large amount, the toughness and weldability are lowered, so the range of 0.03-0.25% is preferable.

상기 Si는 강제조시 중요한 탈산재이며, 동시에 고용강화원소로 작용하지만, 과도하게 함유되면 용접부 인성을 악화시키므로 0.05-0.5% 범위가 바람직하다.The Si is an important deoxidizer during forcing, and at the same time acts as a solid solution strengthening element, but excessively contained deteriorates the toughness of the weld, so the range of 0.05-0.5% is preferable.

상기 Mn은 기본적으로 강도를 확보하기 위하여 첨가되는 원소이지만 과량 함유되면 용접부 인성이 열화되고, 용접성 자체도 나빠지므로 0.5-2.2%의 범위로 첨가하는 것이 바람직하다.The Mn is basically an element added in order to secure strength, but if it is contained in an excessive amount, the toughness of the weld portion is deteriorated and the weldability itself is deteriorated. Therefore, Mn is preferably added in the range of 0.5-2.2%.

상기 Nb는 고온에서 카본나이트라이드 형태로 석출하여 오스테나이트 재결정 및 성장을 억제하여 재결정온도를 높게 하는 원소이며, 석출강화원소이나 과량첨가시 용접부 인성이 열화되므로 0.001-0.1%의 범위로 첨가하는 것이 바람직하다.The Nb is an element that precipitates in the form of carbon nitride at a high temperature to inhibit austenite recrystallization and growth to increase the recrystallization temperature. desirable.

상기 V는 석출강화원소이며 강도확보를 위해 첨가되나 다량 함유되면 용접성이 저하되므로 0.005-0.1%의 범위로 첨가하는 것이 바람직하다.The V is a precipitation strengthening element and is added to secure the strength, but if it contains a large amount, the weldability is lowered, so it is preferably added in the range of 0.005-0.1%.

상기 Ti은 모재 및 용접부의 저온인성향상에 유효한 원소이나 0.05%이상에서는 그 효과가 포화되므로 0.005-0.5%의 범위로 첨가하는 것이 바람직하다.The Ti is an element effective for improving the low temperature toughness of the base metal and the welded part, but the effect is saturated at 0.05% or more, so it is preferably added in the range of 0.005-0.5%.

상기 Al은 탈산을 위해 필수적으로 첨가되는 원소이나 0.1%이상이 함유되면 용접부 인성이 저하되므로 0.001-0.1%의 범위로 첨가하는 것이 바람직하다.Al is preferably added in the range of 0.001-0.1% because the toughness of the weld portion is lowered when 0.1% or more of the element is essentially added for deoxidation.

상기 Cu는 특히 후물재를 생산하는 경우에 강도보강을 위하여 첨가하는 원소이나 다량 첨가하면 용접부 인성이 열화하고 제강에도 난점이 발생하므로 0.001-1.0%의 범위로 첨가하는 것이 바람직하다.The Cu is preferably added in the range of 0.001-1.0% because the toughness of the welded portion is deteriorated and the difficulty in steelmaking occurs when the element is added for the strength reinforcement, especially when producing the thick material.

Ni은 특히 후물재의 경우 저온인성향상을 위하여 첨가하는 원소이나 다량 함유되면 용접부 인성이 열화되므로 0.001-1.0의 범위로 첨가하는 것이 바람직하다.Ni is particularly preferably added in the range of 0.001-1.0 since the toughness of the welded material is deteriorated when the material is added to the low temperature toughness to improve the low temperature toughness.

상기 P는 제강과정에서 불가피하게 함유되는 불순물원소로서 편석되기 쉽고 저온변태조직을 형성하므로 그 상한을 0.02로 제한하는 것이 바람직하다.P is easily impregnated as an impurity element inevitably contained in the steelmaking process and forms a low temperature transformation structure. Therefore, the upper limit thereof is preferably limited to 0.02.

상기 S는 역시 강의 제조상 불가피하게 함유된느 불순물원소로서 비금속개재물을 증가시켜 인성을 열화시키므로 그 상한값을 0.015%로 한정하는 것이 바람직하다.S is an impurity element that is inevitably contained in the manufacture of steel, and thus it is preferable to limit its upper limit to 0.015% because it increases the non-metallic inclusion and degrades toughness.

이하, 본 발명 후강판의 제조방법을 제 1 도를 일례로 상세히 설명한다.Hereinafter, the manufacturing method of the thick steel sheet of the present invention will be described in detail with reference to FIG.

상기와 같이 조성되는 강 슬라브를 1100-1250℃의 온도범위로 가열하고, 내부까지 충분히 가열되도록 2시간이상 유지하는 것이 바람직한데, 그 이유는 1100℃ 이하의 경우 합금원소의 고용화가 안되고, 1250℃ 이상의 경우 오스테나이트 결정입이 조대해지기 때문이다.The steel slab formed as described above is preferably heated to a temperature range of 1100-1250 ° C. and maintained for at least 2 hours to be sufficiently heated to the inside. For 1100 ° C. or less, the alloying element cannot be solidified and 1250 ° C. This is because grains of austenite become coarse in the above cases.

상기와 같이 가열한 후 930-1100℃의 미재결정온도까지 3-20℃/sec의 속도로 냉각하는 것이 바람직한데, 그 이유는 3℃/sec이상은 되어야 생산성향상에 기여할 수 있으며 20℃/sec 이상인 경우는 효과가 포화되며 슬라브의 온도편차도 심해질 수 있기 때문이다. 상기와 같이 냉각한 슬라브는 두께방향으로 적절한 온도편차가 생기는데, 이로 인하여 압연시 판 내부의 변형량이 많아서 내부인성을 향상시킬 수 있는 잇점이 있다. 또한 이러한 온도편차는 최종적으로는 압연이 끝나는 시점에서 온도편차가 30℃ 이내로 줄어들어서 실용상 문제는 발생하지 않는다.After heating as described above, it is preferable to cool to a recrystallization temperature of 930-1100 ° C. at a rate of 3-20 ° C./sec. The reason is that 3 ° C./sec or more may contribute to productivity improvement and 20 ° C./sec. This is because the effect is saturated and the temperature deviation of the slab may be increased. The slab cooled as described above has an appropriate temperature deviation in the thickness direction, and thus, there is an advantage that the internal toughness can be improved due to the large amount of deformation in the plate during rolling. In addition, such a temperature deviation does not occur in practical use since the temperature deviation is finally reduced to within 30 ℃ at the end of rolling.

상기와 같이 냉각한 직후 통상의조건인 65%이상의 누적압하량으로 Ac3변태점온도이상에 마무리 압연한 다음 500℃이상의 온도까지 5-20℃/sec의 속도로 냉각하고, 이후 공냉처리한다.Immediately after cooling as described above, after finishing rolling over Ac 3 transformation point temperature at a cumulative pressure drop of 65% or more, which is a normal condition, it is cooled at a rate of 5-20 ° C./sec to a temperature of 500 ° C. or more, and then air-cooled.

본 발명의 구성에 있어서, 슬라브 재가열온도, 이후 냉각조건 등을 제외한 기타 공정 조업조건은 통상의 방법으로 행하므로 특별히 한정하지 않는다.In the configuration of the present invention, other process operating conditions except for slab reheating temperature, subsequent cooling conditions, and the like are carried out by a conventional method, and are not particularly limited.

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

[실시예]EXAMPLE

본 발명의 압연방법 및 종래압연방법을 적용하였을 때 생산성 및 인성을 비교하기 위하여 상기 표1의 조성을 가지는 강재를 준비하고 실험압연을 하여 결과를 비교하였다. 슬라브 재가열온도는 1250℃에서 2시간을 하였고 슬라브 두께는 220㎜, 최종판 두께는 50㎜로 하였다, 본 발명재는 가열로에서 추출직후 930℃까지 7℃/sec정도의 냉각속도로 수냉한 후 압연을 하였고 냉각속도측정은 슬라브 중앙부에 열전대를 삽입하여 압연공정중에 온도를 측정하여서 계산하였다. 미재결정역 압연이 끝난 후에는 500℃까지 7℃/sec로 가속냉각을 실시한 후 공냉한 다음 제반특성을 측정한 후 그 결과를 하기표 2에 나타내었다.In order to compare the productivity and toughness when the rolling method and the conventional rolling method of the present invention were applied, steels having the composition of Table 1 were prepared and subjected to experimental rolling to compare the results. The slab reheating temperature was 2 hours at 1250 ° C., the slab thickness was 220 mm, and the final plate thickness was 50 mm. The present invention is cooled after cooling with water at a cooling rate of about 7 ° C./sec to 930 ° C. immediately after extraction in a heating furnace. The cooling rate was measured by inserting a thermocouple in the center of the slab and measuring the temperature during the rolling process. After the end of the non-recrystallized rolling, the accelerated cooling was performed at 7 ° C./sec to 500 ° C., followed by air cooling, and the overall characteristics thereof were measured. The results are shown in Table 2 below.

상기 표2에서 알 수 있는 바와 같이 본 발명재(1)의 후물강재는 추출직후 급냉에 의하여 생산성이 향상되고 인성도 향상되는 효과가 현저하였다.As can be seen in Table 2, the thick steel material of the present invention (1) was remarkably effective in improving productivity and toughness by quenching immediately after extraction.

상술한 바와 같이, 본 발명은 압연공정을 적절히 제어함으로써 종래재 대비 우수한 생산성과 인성이 향상되는 고인성 후강판을 제공할 수 있고, 또한 상기 제공된 후강판은 제조원가를 낮출 수 있는 효과가 있다.As described above, the present invention can provide a high toughness thick steel sheet that is excellent in productivity and toughness compared to conventional materials by appropriately controlling the rolling process, and the thick steel sheet provided above has the effect of lowering the manufacturing cost.

Claims (1)

두께가 35㎜ 이상의 후강판을 제어압연 또는 가속냉각 방법으로 제조하는 방법에 있어서,In the method of manufacturing a thick steel sheet having a thickness of 35mm or more by controlled rolling or accelerated cooling method, 중량%로 C:0.03-0.25%, Si:0.05-0.5%, Mn:0.5-2.2%, Nb:0.005-0.1%, V:0.005-0.1%, Ti:0.001-0.05%, Cu:0.001-1.0%, Ni:0.001-1.0%, Al:0.001-0.1%, P:0.02%이하, S:0.015%이하, 나머지 Fe 및 기타 불가피하게 함유하는 불순물로 이루어진 강 슬라브를 1100-1250℃의 온도범위로 가열하여, 이 온도에서 2시간이상 유지한 후 930-1000℃의 온도범위까지 3-20℃/sec의 속도로 냉각한 다음, 누적압하량 65% 이상으로 Ac3이상의 마무리압연온도 조건으로 압연한 후, 500℃ 이상의 온도까지 5-20℃/sec의 속도로 냉각하고, 이후 공냉함을 특징으로 하는 생산성이 우수한, 고인성 후강판의 제조방법.By weight% C: 0.03-0.25%, Si: 0.05-0.5%, Mn: 0.5-2.2%, Nb: 0.005-0.1%, V: 0.005-0.1%, Ti: 0.001-0.05%, Cu: 0.001-1.0 Steel slab consisting of%, Ni: 0.001-1.0%, Al: 0.001-0.1%, P: 0.02% or less, S: 0.015% or less, remaining Fe and other unavoidable impurities in the temperature range of 1100-1250 ° C After heating for 2 hours or more at this temperature, it is cooled at a rate of 3-20 ° C / sec to a temperature range of 930-1000 ° C, and then rolled at a finish rolling temperature of Ac 3 or more at a cumulative reduction of 65% or more. Thereafter, cooling to a temperature of 500 ° C or higher at a rate of 5-20 ° C / sec, and then excellent in productivity, characterized in that the air-cooled thick steel sheet manufacturing method.
KR1019960065175A 1996-12-13 1996-12-13 Method for producing steel plate having superior toughness with increased productivity KR100293193B1 (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR100431852B1 (en) * 1999-12-28 2004-05-20 주식회사 포스코 A method for manufacturing high strength thick steel sheet and a vessel by deep drawing

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR100431852B1 (en) * 1999-12-28 2004-05-20 주식회사 포스코 A method for manufacturing high strength thick steel sheet and a vessel by deep drawing

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