WO2017219549A1 - 一种250mm厚的S355NL低碳高韧性低合金钢板及其制造方法 - Google Patents

一种250mm厚的S355NL低碳高韧性低合金钢板及其制造方法 Download PDF

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WO2017219549A1
WO2017219549A1 PCT/CN2016/102558 CN2016102558W WO2017219549A1 WO 2017219549 A1 WO2017219549 A1 WO 2017219549A1 CN 2016102558 W CN2016102558 W CN 2016102558W WO 2017219549 A1 WO2017219549 A1 WO 2017219549A1
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steel plate
slab
temperature
low
continuous casting
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PCT/CN2016/102558
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English (en)
French (fr)
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刘海宽
李经涛
高助忠
张建
张军
恽鹏程
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江阴兴澄特种钢铁有限公司
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Publication of WO2017219549A1 publication Critical patent/WO2017219549A1/zh

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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/26—Methods of annealing
    • C21D1/28—Normalising
    • 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
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/005—Heat treatment of ferrous alloys containing Mn
    • 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
    • C21D8/0226—Hot rolling
    • 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
    • C21D8/0263—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment following hot 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
    • C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/08—Ferrous alloys, e.g. steel alloys containing nickel
    • 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

Definitions

  • the present invention belongs to the field of steel sheet manufacturing, and particularly relates to a low carbon high toughness low alloy S355 NL steel sheet having a thickness of 250 mm and a manufacturing method thereof.
  • Low-alloy extra-thick steel plates are mainly used for important structural components in wind power, bridges, hydropower, etc., and have strict requirements on the internal quality, welding performance, low-temperature impact performance and laminar tear resistance of the products.
  • the greater the thickness of the steel plate the more serious the metallurgical defects such as looseness and segregation inside, and the different thickness and mixed crystals appear with the increase of the thickness of the steel plate, which eventually leads to the obvious deterioration of the impact toughness of the steel plate, especially the heart part -50°.
  • C shock energy fluctuates greatly, which seriously affects the use of steel plates in alpine regions.
  • the invention patent of the publication No. CN103014283A relates to "a method for manufacturing a special thick steel plate for a continuous casting slab production hydropower station", and provides a special thick steel plate with a -40 ° C impact energy of 150 J or more, and a heat treatment process thereof Austenitic quenching + sub-temperature quenching + high temperature tempering, complex process, high production cost, and the maximum thickness of the steel plate is only 150mm, which can not meet the increasing demand for steel plate thickness.
  • the invention patent of CN104962814A relates to a "normalized high strength and toughness 150mm thick steel plate and a production method thereof", and provides a special thick steel plate with an impact energy of >60-150J at -60 °C.
  • the production process adopts controlled rolling + normalizing + weak cooling.
  • the low temperature impact toughness can meet the requirement of -60 °C, the impact energy fluctuation range is large, and the maximum thickness of the steel plate is only 150 mm, which can not meet the market's increasing thickness of the steel plate. Big demand.
  • the invention patent of CN104911475A relates to a "low-carbon medium-manganese high-strength and toughness extra-thick steel plate and a preparation method thereof", and provides a special thick steel plate with a -60 ° C impact energy of >100 J,
  • the heat treatment process adopts quenching + tempering. Although it can meet the impact energy of -60 °C, the maximum thickness of the steel plate is only 140 mm, which can not meet the increasing demand for steel plate thickness.
  • the invention patent of CN102029305A relates to a "method for producing a special thick steel plate", which provides a special thick steel plate, which has simple composition design and does not require heat treatment, but can only meet -20 ° C. Shock The maximum thickness of the steel plate is only 150mm, which also cannot meet the increasing demand for steel plate thickness.
  • the technical problem to be solved by the present invention is to provide a S355 NL low carbon high toughness low alloy extra-thick steel plate with a thickness of 250 mm for the above prior art, which can be applied to the manufacture of important structural components such as wind power and bridges, and has good Internal quality, excellent low temperature impact toughness and good overall mechanical properties.
  • Another object of the present invention is to provide a method for producing a low carbon high toughness low alloy extra-thick steel plate. It is produced by 450 mm continuous casting billet and the heat treatment process is normalized. It can guarantee the excellent low temperature impact toughness and good comprehensive mechanical properties of the 250mm thick steel plate.
  • the impact energy of -50°C is above 150J.
  • the production process of the invention is simple and suitable for mass production, and there is currently no similar steel product.
  • the technical solution adopted by the present invention to solve the above technical problem is a 250 mm thick S355NL low carbon high toughness low alloy steel plate, the chemical composition of the steel plate is C: 0.07 ⁇ 0.14% by weight, Si: 0.15 ⁇ 0.25 ⁇ 3 ⁇ 4, Mn: 1.40 ⁇ 1.60 ⁇ 3 ⁇ 4, P: ⁇ 0.006%, S: ⁇ 0.001%, A1: 0.02 ⁇ 0.06 ⁇ 3 ⁇ 4, Nb: 0.02 ⁇ 0.05 ⁇ 3 ⁇ 4, V: 0.02 ⁇ 0.05 ⁇ 3 ⁇ 4, Ni : 0.30 ⁇ 0.50 ⁇ 3 ⁇ 4, the balance is Fe and unavoidable impurity elements.
  • the invention belongs to a 250mm thick S355NL low carbon high toughness low alloy extra-thick steel plate, and its mechanical properties satisfy: yield strength ⁇ 325Mp a , tensile strength ⁇ 500Mp a , elongation after fracture ⁇ 30 ⁇ 3 ⁇ 4, heart
  • the longitudinal impact work value of the section -50 °C is ⁇ 1501
  • the shrinkage of the tensile section in the thickness direction is ⁇ 60%.
  • Steel plate UT inspection can meet NB/T47013.3 Class I requirements.
  • the chemical composition of the low carbon high toughness S355NL low alloy extra-thick steel plate of the present invention is determined as follows:
  • composition of the present invention is mainly designed by using low carbon, low sulfur phosphorus, Nb+V microalloying components, and adding appropriate amount of Ni element to improve low temperature impact toughness.
  • the role of chemical elements in steel is as follows:
  • C Carbon can significantly increase the strength of the steel sheet, but if the content is too high, the shape and impact toughness of the steel sheet will be deteriorated.
  • the carbon content of this patent is controlled at 0.07 to 0.14%.
  • Mn Manganese is a good deoxidizer and desulfurizer in the steel making process, which can improve the strength and toughness of the steel sheet. However, if the content is too high, the segregation of the continuous casting billet will be severe. The manganese content of the patent is controlled at 1.40 ⁇ 1.60%.
  • Si Silicon is a good reducing agent and deoxidizer in the steel making process, but the excessive content will reduce the impact toughness and the surface quality of the steel sheet. The silicon content of this patent is controlled at 0.15 ⁇ 0.25%.
  • Phosphorus is a harmful element, which increases the cold brittleness of steel, and deteriorates the plasticity and welding performance, and should be minimized.
  • the phosphorus content of this patent is controlled below 0.006%.
  • S Sulfur is a harmful element, which increases the hot brittleness of steel, reduces toughness and ductility, and is unfavorable for welding performance, and should be minimized.
  • the sulfur content of this patent is controlled below 0.001%.
  • Ni Nickel can significantly improve the low temperature impact toughness, and the strength can be increased, but the production cost is increased, and the use should be controlled.
  • the nickel content of this patent is controlled at 0.30 to 0.50%.
  • Nb, V bismuth, vanadium microalloying elements and.
  • N element forms carbonitride, which has the effect of delaying austenite recrystallization and refining ferrite grains, which can improve the strength and toughness of the steel plate.
  • the Nb content of this patent is controlled at 0.02 ⁇ 0.05 ⁇ 3 ⁇ 4, V content control. At 0.02 ⁇ 0.05 ⁇ 3 ⁇ 4.
  • 450mm continuous casting slab adopts segment heating mode: the total heating time is 550 ⁇ 650min, the first heating stage temperature is 1050 ⁇ 1150°C, the second heating stage temperature is 1200 ⁇ 1260°C, the soaking section The temperature is 1180 ⁇ 12 50 °C, and the total heating interval between the second heating section and the soaking section is ⁇ 300min, which ensures that the slab segregation is fully diffused.
  • the rolling process adopts a "high temperature and large pressure reduction" process to make the looseness fully press-fit, and improve the internal quality of the steel sheet and the low temperature impact toughness of the core.
  • the rolling temperature is 1060-1100 ° C
  • the finishing temperature is 980-1020 ° C
  • the single pass reduction is 50 mm and above
  • the rolling is completed in 3-4 passes.
  • the stacking is slow and ⁇ 72 hours, and the hydrogen is fully expanded.
  • normalizing temperature is 900 ⁇ 10°C
  • insulation daytime coefficient 2.4 ⁇ 2.6min/mm
  • the steel plate is placed separately after being placed off the line.
  • the present invention has the following features:
  • the present invention relates to a 250 mm thick S355NL low carbon high toughness low alloy extra-thick steel plate which is produced by using a 450 mm continuous casting billet, which has excellent low temperature impact toughness and good comprehensive mechanical properties after normalizing.
  • the present invention adopts a low carbon component design to improve the low temperature impact toughness of the steel sheet by improving the purity of the molten steel and the internal quality of the continuously cast slab.
  • the key technical measures are: 1) by lowering 8, P, H, 0 , N element content increases the purity of molten steel; 2) Reduces segregation and loose defects of slab by continuous soft rolling technology; 3) Improves low temperature impact toughness of steel by reducing carbon content, adding Ni element and improving the purity of molten steel.
  • the Nb+V microalloying composition is designed to compensate for the decrease in strength due to the reduced carbon content, ensuring excellent low temperature impact toughness and good overall mechanical properties after normalizing the steel sheet; 4) Segregation by heating the crucible at a high temperature section of the billet Fully diffused, the same high temperature and large rolling process is adopted to make the looseness fully press, thereby improving the internal quality of the steel plate and the low temperature impact toughness of the core; 5) The ferrite crystal caused by the air cooling after normalizing to prevent the cooling from being too slow The coarse grain size causes the low-temperature impact toughness of the steel sheet to decrease.
  • the steel plate of the invention is produced by using a 450 mm continuous casting billet, has a simple heat treatment process, and has low production cost, and is suitable for mass production.
  • the thickness of the S355NL steel sheet of this embodiment is 250 mm, and its chemical composition is in weight percent: C:
  • the balance is Fe and inevitable impurity elements. [0038]
  • the manufacturing process of the steel sheet is as follows:
  • the 450 mm continuous casting slab adopts a sectional heating method: the total heating time is 600 min, and the temperature of the first heating section is
  • the temperature of the second heating section is 1240 ° C
  • the temperature of the soaking section is 1220 ° C
  • the second heating section and the soaking section are between ⁇ 300 min of total heating time to ensure that the slab segregation is fully diffused.
  • the rolling process adopts a "high temperature and large pressure reduction" process to make the looseness fully press-fit and improve the internal quality and core performance of the steel sheet.
  • the rolling temperature was 1080 ° C
  • the finishing temperature was 1000 ° C
  • the single pass reduction was 50 mm
  • the rolling was completed in 4 passes.
  • the normalizing temperature is 900 ⁇ 10°C
  • the thermal insulation coefficient is 2.5min/mm
  • air cooling in order to ensure the cooling effect after normalizing, the steel plate is placed separately after being laid off.
  • the thickness of the S355NL steel sheet of this embodiment is 250 mm, and its chemical composition is in weight percent: C: 0.12%, Si: 0.20%, Mn: 1.52%, P: 0.004%, S: 0.0005%, Nb: 0.032%, V: 0.035%, Alt: 0.030%, Ni: 0.42%, H: 0.00005%, 0: 0.0010%, N: 0.0024%
  • the balance is Fe and inevitable impurity elements.
  • the 450 mm continuous casting slab adopts a segment heating method: the total heating time is 620 min, and the temperature of the first heating section is
  • the temperature of the second heating section is 1245 ° C
  • the temperature of the soaking section is 1230 ° C
  • the second heating section and the soaking section are between ⁇ 300 min of total heating time to ensure that the slab segregation is fully diffused.
  • the rolling process adopts a "high temperature and large pressure reduction" process to make the looseness fully press-fit and improve the internal quality and core performance of the steel sheet.
  • the rolling temperature was 1070 ° C
  • the finishing temperature was 995 ° C
  • the single pass reduction was 50 mm
  • the rolling was completed in 4 passes.
  • the normalizing temperature is 900 ⁇ 10° C.
  • the thermal insulation interturn coefficient: 2.6 min/mm air cooling; in order to ensure the cooling effect after normalizing, the steel plate is placed separately after being laid off.
  • the S355NL steel sheet of the present embodiment has a thickness of 250 mm, and its chemical composition is expressed by weight: C:
  • the balance is Fe and inevitable impurity elements.
  • the 450 mm continuous casting slab adopts a segment heating method: the total heating time is 625 min, and the temperature of the first heating section is
  • the temperature of the second heating section is 1225 ° C
  • the temperature of the soaking section is 1235 ° C
  • the total heating section of the second heating section and the soaking section is ⁇ 300 min, ensuring that the slab segregation is fully diffused.
  • the rolling process adopts a "high temperature and large pressure reduction" process to make the looseness sufficiently press-fit and improve the internal quality and core performance of the steel sheet.
  • the rolling temperature was 1065 ° C
  • the finishing temperature was 985 ° C
  • the single pass reduction was 50 mm
  • the rolling was completed in 4 passes.
  • the normalizing temperature is 900 ⁇ 10° C.
  • the thermal insulation interturn coefficient: 2.6 min/mm air cooling; in order to ensure the cooling effect after normalizing, the steel plate is placed separately after being laid off.

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Abstract

一种250mm厚的S355NL低碳高韧性低合金钢板，化学成分按重量百分比计为C：0.07～0.14％，Si：0.15～0.25％，Mn：1.40～1.60％，P：≤0.006％，S：≤0.001％，Al：0.02～0.06％，Nb：0.02～0.05％，V：0.02～0.05％，Ni：0.30～0.50％，余量为Fe及不可避免的杂质元素。生产工艺：KR预处理→转炉冶炼→LF精炼→RH精炼→板坯连铸→板坯缓冷→板坯加热→钢板轧制→钢板缓冷→探伤→正火→精整→检验→入库。本申请钢板采用450mm连铸坯生产，热处理工艺简单，生产成本较低，适合批量生产，正火后具有优异的低温冲击韧性和良好的综合机械性能。

Description

说明书
发明名称：一种 250mm厚的 S355NL低碳高韧性低合金钢板及其制 造方法
技术领域
[0001] 本发明属于钢板制造领域， 具体涉及一种厚度为 250mm低碳高韧性低合金 S355 NL钢板及其制造方法。
背景技术
[0002] 低合金特厚钢板主要用于风电、 桥梁、 水电等领域重要结构部件， 对产品的内 部质量、 焊接性能、 低温冲击性能和抗层状撕裂性能都有严格要求。 钢板厚度 越大， 其内部疏松、 偏析等冶金缺陷越严重， 而且随着钢板厚度的增加会出现 不同程度的粗晶和混晶， 最终导致钢板冲击韧性明显变差， 尤其是心部 -50°C冲 击功波动较大， 严重影响了钢板在高寒地区的使用。
[0003] 公告号为 CN103014283A的发明专利涉及"一种连铸板坯生产水电站用特厚钢板 的制造方法"， 提供了一种 -40°C冲击功在 150J以上的特厚钢板， 其热处理工艺采 用奥氏体化淬火 +亚温淬火 +高温回火， 工艺复杂， 生产成本高， 且钢板最大厚 度只有 150mm， 不能满足市场对钢板厚度越来越大的需求。
[0004] 公告号为 CN104962814A的发明专利涉及一种 "一种正火高强韧性 150mm特厚钢 板及其生产方法"， 提供了一种 -60°C冲击功在〉 40-150J的特厚钢板， 其生产工艺 采用控轧 +正火 +弱冷， 低温冲击韧性虽然可以满足 -60°C要求， 但冲击功波动范 围较大， 且钢板最大厚度只有 150mm， 同样不能满足市场对钢板厚度越来越大 的需求。
[0005] 公告号为 CN104911475A的发明专利涉及一种 "一种低碳中锰高强韧性特厚钢板 及其制备方法"， 提供了一种 -60°C冲击功在〉 100J的特厚钢板， 其热处理工艺采 用淬火 +回火， 虽然可以满足 -60°C冲击功具有较大余量， 但钢板最大厚度只有 14 0mm, 同样不能满足市场对钢板厚度越来越大的需求。
[0006] 公告号为 CN102029305A的发明专利涉及一种 "一种特厚钢板的生产方法"， 提 供了一种特厚钢板， 其成分设计简单， 且不需要热处理， 但只能满足 -20°C冲击 要求， 钢板最大厚度只有 150mm， 同样不能满足市场对钢板厚度越来越大的需 求。
技术问题
[0007] 本发明所要解决的技术问题是针对上述现有技术提供一种厚度为 250mm的 S355 NL低碳高韧性低合金特厚钢板， 可应用于风电和桥梁等重要结构部件的制造， 具有良好的内部质量、 优异的低温冲击韧性和良好的综合机械性能。
[0008] 本发明另一目的是提供一种低碳高韧性低合金特厚钢板的制造方法。 采用 450 mm连铸坯生产， 热处理工艺采用正火处理， 可保证 250mm厚度钢板具有优异的 低温冲击韧性和良好的综合机械性能， 其中 -50°C冲击功在 150J以上。 本发明产 品生产工艺简单， 适合批量生产， 目前还没有公幵相类似钢材产品。
问题的解决方案
技术解决方案
[0009] 本发明解决上述技术问题所采用的技术方案为， 一种 250mm厚的 S355NL低碳 高韧性低合金钢板， 该钢板的化学成分按重量百分比计为 C: 0.07〜0.14%， Si: 0.15〜0.25<¾， Mn: 1.40〜1.60<¾， P: <0.006% , S: <0.001% , A1: 0.02〜0.06<¾ ， Nb: 0.02〜0.05<¾， V： 0.02〜0.05<¾， Ni: 0.30〜0.50<¾， 余量为 Fe及不可避 免的杂质元素。
[0010] 进一步讲， 本发明属于 250mm厚 S355NL低碳高韧性低合金特厚钢板， 其机械 性能满足： 屈服强度≥325Mpa， 抗拉强度≥500Mpa， 断后伸长率≥30<¾， 心部 -50 °C纵向冲击功单值≥1501， 厚度方向拉伸断面收缩率≥60%。 钢板 UT探伤可满足 NB/T47013.3 I级要求。
[0011] 本发明低碳高韧性 S355NL低合金特厚钢板的化学成分是这样确定的：
[0012] 本发明的成分主要采用低碳、 低硫磷、 Nb+V微合金化成分设计， 同吋添加适 量 Ni元素， 提高低温冲击韧性。 化学元素在钢中的作用如下：
[0013] C: 碳能够显著提高钢板的强度， 但含量过高吋会使钢板塑形和冲击韧性变差 ， 本专利碳含量控制在 0.07〜0.14%。
[0014] Mn: 锰在炼钢过程中是良好的脱氧剂和脱硫剂， 可以提高钢板强度和韧性， 但含量过高会导致连铸坯偏析严重， 本专利锰含量控制在 1.40〜1.60%。 [0015] Si: 硅是在炼钢过程中是良好的还原剂和脱氧剂， 但含量过高会降低冲击韧性 和钢板表面质量， 本专利硅含量控制在 0.15〜0.25%。
[0016] P:磷是有害元素， 增加钢的冷脆性， 使塑性和焊接性能变差， 应尽量降低， 本 专利磷含量控制在 0.006%以下。
[0017] S: 硫是有害元素， 增加钢的热脆性， 降低韧性和延展性， 对焊接性能不利， 应尽量降低， 本专利硫含量控制在 0.001%以下。
[0018] Ni :镍能显著提高低温冲击韧性， 同吋可以提高强度， 但会增加生产成本， 应 控制使用， 本专利镍含量控制在 0.30〜0.50%。
[0019] Nb、 V： 铌、 钒微合金元素与。、 N元素形成碳氮化物， 具有推迟奥氏体再结 晶， 细化铁素体晶粒的作用， 可以同吋提高钢板强度和韧性， 本专利 Nb含量控 制在 0.02〜0.05<¾、 V含量控制在 0.02〜0.05<¾。
[0020] 上述低碳高韧性 250mm低合金特厚钢板的制造方法。
[0021] 生产工艺流程： KR预处理→转炉冶炼—LF精炼→RH精炼→板坯连铸→板坯缓 冷→板坯加热→钢板轧制→钢板缓冷→探伤→正火→精整→检验→入库。
[0022] 主要工序的具体操作如下，
[0023] 1) 冶炼工艺
[0024] 采用 450mm连铸板坯生产， 通过降低钢中 S、 P、 H、 0、 N元素含量来提高钢 水纯净度、 降低铸坯偏析， 冶炼原料经 KR铁水预处理， 转炉冶炼后扒澄处理， 严格控制8≤0.001<¾， P<0.006% , H≤1.2ppm, O≤20ppmm, N≤40ppm; 通过连 铸工序动态轻压下技术控制铸坯偏析在 C类 1.0级以下， 疏松在 0.5级以下； 板坯 下线后加罩缓冷 48小吋以上， 确保钢中的氢充分扩散。
[0025] 2) 加热、 轧制工艺
[0026] 450mm连铸板坯采用分段加热方式： 总加热吋间为 550〜650min， 第一加热段 温度为 1050〜1150°C， 第二加热段温度为 1200〜1260°C， 均热段温度为 1180〜12 50°C， 第二加热段和均热段总加热吋间≥300min， 确保铸坯偏析充分扩散。
[0027] 轧制工序采用"高温大压下"工艺， 使疏松充分压合， 提高钢板内部质量和心部 低温冲击韧性。 幵轧温度为 1060-1100°C， 终轧温度为 980-1020°C， 单道次压下 量为 50mm及以上， 3-4个道次完成轧制。 [0028] 钢板下线后堆垛缓冷≥72小吋， 充分扩氢。
[0029] 3) 热处理工艺
[0030] 采用正火工艺， 正火温度为 900±10°C， 保温吋间系数： 2.4〜2.6min/mm， 风冷
； 为了保证正火后冷却效果， 钢板下线后单独摆放。
发明的有益效果
有益效果
[0031] 与现有技术相比， 本发明具有如下特点：
[0032] 本发明涉及一种 250mm厚 S355NL低碳高韧性低合金特厚钢板， 该钢板采用 450 mm连铸坯生产， 正火后具有优异的低温冲击韧性和良好的综合机械性能。
[0033] 为了实现上述目的， 本发明采用低碳成分设计， 通过提高钢水纯净度和连铸板 坯内部质量来提高钢板低温冲击韧性， 关键技术措施： 1) 通过降低8、 P、 H、 0、 N元素含量提高钢水纯净度； 2) 通过连铸动态轻压下技术减轻铸坯偏析和疏 松缺陷； 3) 通过降低碳含量、 添加 Ni元素以及提高钢水纯净度来提高钢板低温 冲击韧性， 采用 Nb+V微合金化成分设计弥补由于降低碳含量所带来的强度下降 ， 确保钢板正火后具有优异的低温冲击韧性和良好的综合机械性能； 4) 通过延 长坯料高温段加热吋间使偏析充分扩散， 同吋采用高温大压下轧制工艺使疏松 充分压合， 进而提高钢板内部质量和心部低温冲击韧性； 5) 通过正火后风冷， 防止冷却太慢造成的铁素体晶粒粗大导致钢板低温冲击韧性下降。
[0034] 与现有技术相比， 本发明钢板采用 450mm连铸坯生产， 热处理工艺简单， 生产 成本较低， 适合批量生产。
实施该发明的最佳实施例
本发明的最佳实施方式
[0035] 以下结合实施例对本发明作进一步详细描述。
[0036] 实施例 1
[0037] 本实施例的 S355NL钢板的厚度为 250mm， 其化学成分按重量百分比计为： C:
0.11% , Si: 0.22% , Mn: 1.51% , P: 0.005% , S: 0.0008% , Nb: 0.035% , V： 0.035% , Alt: 0.032% , Ni: 0.40% , H: 0.00006% , 0： 0.0012% , N: 0.0026%
， 余量为 Fe及不可避免的杂质元素。 [0038] 该钢板的制造工艺为如下：
[0039] 采用 450mm厚连铸板坯生产， 生产工艺路线： KR预处理→转炉冶炼—LF精炼 →RH精炼→板坯连铸→板坯缓冷→板坯加热→钢板轧制→钢板缓冷→探伤→正 火→精整→检验→入库。
[0040] 1) 冶炼工艺
[0041] 采用 450mm连铸板坯生产， 通过降低钢中 S、 P、 H、 0、 N元素含量来提高钢 水纯净度、 降低铸坯偏析， 冶炼原料经 KR铁水预处理， 转炉冶炼后扒澄处理， 严格控制8≤0.001<¾， P<0.006% , H≤1.2ppm, O≤20ppmm, N≤40ppm; 通过连 铸工序动态轻压下技术控制铸坯偏析在 C类 1.0级以下， 疏松在 0.5级以下； 板坯 下线后加罩缓冷 48小吋以上， 确保钢中的氢充分扩散。
[0042] 2) 加热、 轧制工艺
[0043] 450mm连铸板坯采用分段加热方式： 总加热吋间为 600min， 第一加热段温度为
1120°C， 第二加热段温度为 1240°C， 均热段温度为 1220°C， 第二加热段和均热段 总加热吋间≥300min， 确保铸坯偏析充分扩散。
[0044] 轧制工序采用"高温大压下"工艺， 使疏松充分压合， 提高钢板内部质量和心部 性能。 幵轧温度为 1080°C， 终轧温度为 1000°C， 单道次压下量为 50mm， 4个道次 完成轧制。
[0045] 钢板下线后堆垛缓冷≥72小吋， 充分扩氢。
[0046] 3) 热处理工艺
[0047] 采用正火工艺， 正火温度为 900±10°C， 保温吋间系数： 2.5min/mm， 风冷； 为 了保证正火后冷却效果， 钢板下线后单独摆放。
[0048] 经由上述制造工艺制得的 250mm厚 S355NL低碳高韧性特厚钢板， UT探伤满足
NB/T47013.3标准 I级要求， 具有优异的低温冲击韧性和良好的综合机械性能详见 表 1。
本发明的实施方式
[0049] 实施例 2
[0050] 本实施例的 S355NL钢板的厚度为 250mm， 其化学成分按重量百分比计为： C: 0.12% , Si: 0.20% , Mn: 1.52% , P: 0.004% , S: 0.0005% , Nb: 0.032% , V： 0.035% , Alt: 0.030% , Ni: 0.42% , H: 0.00005% , 0： 0.0010% , N: 0.0024%
， 余量为 Fe及不可避免的杂质元素。
[0051] 该钢板的制造工艺为如下：
[0052] 采用 450mm厚连铸板坯生产， 生产工艺路线： KR预处理→转炉冶炼—LF精炼 →RH精炼→板坯连铸→板坯缓冷→板坯加热→钢板轧制→钢板缓冷→探伤→正 火→精整→检验→入库。
[0053] 1) 冶炼工艺
[0054] 采用 450mm连铸板坯生产， 通过降低钢中 S、 P、 H、 0、 N元素含量来提高钢 水纯净度、 降低铸坯偏析， 冶炼原料经 KR铁水预处理， 转炉冶炼后扒澄处理， 严格控制8≤0.001<¾， P<0.006% , H≤1.2ppm, O≤20ppmm, N≤40ppm; 通过连 铸工序动态轻压下技术控制铸坯偏析在 C类 1.0级以下， 疏松在 0.5级以下； 板坯 下线后加罩缓冷 48小吋以上， 确保钢中的氢充分扩散。
[0055] 2) 加热、 轧制工艺
[0056] 450mm连铸板坯采用分段加热方式： 总加热吋间为 620min， 第一加热段温度为
1125°C， 第二加热段温度为 1245°C， 均热段温度为 1230°C， 第二加热段和均热段 总加热吋间≥300min， 确保铸坯偏析充分扩散。
[0057] 轧制工序采用"高温大压下"工艺， 使疏松充分压合， 提高钢板内部质量和心部 性能。 幵轧温度为 1070°C， 终轧温度为 995°C， 单道次压下量为 50mm， 4个道次 完成轧制。
[0058] 钢板下线后堆垛缓冷≥72小吋， 充分扩氢。
[0059] 3) 热处理工艺
[0060] 采用正火工艺， 正火温度为 900±10°C， 保温吋间系数： 2.6min/mm， 风冷； 为 了保证正火后冷却效果， 钢板下线后单独摆放。
[0061] 经由上述制造工艺制得的 250mm厚 S355NL低碳高韧性特厚钢板， UT探伤满足
NB/T47013.3标准 I级要求， 具有优异的低温冲击韧性和良好的综合机械性能详见 表 1。
[0062] [0063] 实施例 3
[0064] 本实施例的 S355NL钢板的厚度为 250mm， 其化学成分按重量百分比计为： C:
0.12% , Si: 0.23% , Mn: 1.55% , P: 0.004% , S: 0.0005% , Nb: 0.030% , V： 0.038% , Alt: 0.035% , Ni: 0.45% , H: 0.00008% , 0： 0.0012% , N: 0.0028%
， 余量为 Fe及不可避免的杂质元素。
[0065] 该钢板的制造工艺为如下：
[0066] 采用 450mm厚连铸板坯生产， 生产工艺路线： KR预处理→转炉冶炼—LF精炼 →RH精炼→板坯连铸→板坯缓冷→板坯加热→钢板轧制→钢板缓冷→探伤→正 火→精整→检验→入库。
[0067] 1) 冶炼工艺
[0068] 采用 450mm连铸板坯生产， 通过降低钢中 S、 P、 H、 0、 N元素含量来提高钢 水纯净度、 降低铸坯偏析， 冶炼原料经 KR铁水预处理， 转炉冶炼后扒澄处理， 严格控制8≤0.001<¾， P<0.006% , H≤1.2ppm, O≤20ppmm, N≤40ppm; 通过连 铸工序动态轻压下技术控制铸坯偏析在 C类 1.0级以下， 疏松在 0.5级以下； 板坯 下线后加罩缓冷 48小吋以上， 确保钢中的氢充分扩散。
[0069] 2) 加热、 轧制工艺
[0070] 450mm连铸板坯采用分段加热方式： 总加热吋间为 625min， 第一加热段温度为
1118°C， 第二加热段温度为 1225°C， 均热段温度为 1235°C， 第二加热段和均热段 总加热吋间≥300min， 确保铸坯偏析充分扩散。
[0071] 轧制工序采用"高温大压下"工艺， 使疏松充分压合， 提高钢板内部质量和心部 性能。 幵轧温度为 1065°C， 终轧温度为 985°C， 单道次压下量为 50mm， 4个道次 完成轧制。
[0072] 钢板下线后堆垛缓冷≥72小吋， 充分扩氢。
[0073] 3) 热处理工艺
[0074] 采用正火工艺， 正火温度为 900±10°C， 保温吋间系数： 2.6min/mm， 风冷； 为 了保证正火后冷却效果， 钢板下线后单独摆放。
工业实用性
[0075] 经由上述制造工艺制得的 250mm厚 S355NL低碳高韧性特厚钢板， UT探伤满足 NB/T47013.3标准 I级要求， 具有优异的低温冲击韧性和良好的综合机械性能详见 表 1。
[0076]
[0077] 表 1各实施例所生产的钢板的机械性能
[]
Figure imgf000009_0001
[0078] 注： （） 内为平均值
序列表自由内容
[0079] 在此处键入序列表自由内容描述段落。

Claims

权利要求书
[权利要求 1] 一种 250mm厚的 S355NL低碳高韧性低合金钢板， 其特征在于： 该钢 板的化学成分按重量百分比计为 C: 0.07—0.14% , Si: 0.15〜0.25% ， Mn: 1.40〜1.60<¾， P: <0.006% , S: <0.001% , A1: 0.02〜0.06<¾ ， Nb: 0.02〜0.05<¾， V： 0.02〜0.05<¾，
Ni: 0.30〜0.50%， 余量为 Fe及不可避免的杂质元素。
[权利要求 2] 根据权利要求 1所述的 250mm厚的 S355NL低碳高韧性低合金钢板， 其 特征在于： 钢板成品的机械性能满足： 屈服强度≥325Mpa， 抗拉强度 >500Mpa, 断后伸长率≥30%， 心咅^ 50°C纵向冲击功单值≥150>， 厚 度方向拉伸断面收缩率≥60%， 钢板 UT探伤可满足 NB/T47013.3 I级要 求。
[权利要求 3] —种制造如权利要求 1所述 250mm厚的 S355NL低碳高韧性低合金钢板 的方法， 其特征在于：
生产工艺路线： KR预处理→转炉冶炼—LF精炼→RH精炼→板坯连铸 →板坯缓冷→板坯加热→钢板轧制→钢板缓冷→探伤→正火→精整→ 检验→入库；
主要工序的具体操作如下，
1) 冶炼工艺
450mm连铸板坯生产， 通过降低钢中 S、 P、 H、 0、 N元素含量来提 高钢水纯净度、 降低铸坯偏析， 冶炼原料经 KR铁水预处理， 转炉冶 炼后扒澄处理， 控制 S≤0.001<¾， P<0.006% , H≤1.2ppm, O≤20ppmm ， N≤40ppm; 通过连铸工序动态轻压下技术控制铸坯偏析在 C类 1.0级 以下， 疏松在 0.5级以下； 板坯下线后加罩缓冷 48小吋以上；
2) 加热、 轧制工艺
450mm连铸板坯采用分段加热方式： 总加热吋间为 550〜650min， 第 一加热段温度为 1050〜1150°C， 第二加热段温度为 1200〜1260°C， 均 热段温度为 1180〜1250°C， 第二加热段和均热段总加热吋间≥300min 轧制工序采用"高温大压下"工艺， 幵轧温度为 1060〜1100°C， 终轧温 度为 980〜1020°C， 单道次压下量在 50mm及以上， 3-4个道次完成轧 制；
钢板下线后堆垛缓冷≥72小吋， 充分扩氢；
3) 热处理工艺
采用正火工艺， 正火温度为 900±10°C， 保温吋间系数： 2.4〜2.6min/ mm, 风冷； 为了保证正火后冷却效果， 钢板下线后单独摆放。
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