WO2020237976A1 - 一种超细针状组织结构钢及其生产方法 - Google Patents

一种超细针状组织结构钢及其生产方法 Download PDF

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WO2020237976A1
WO2020237976A1 PCT/CN2019/111416 CN2019111416W WO2020237976A1 WO 2020237976 A1 WO2020237976 A1 WO 2020237976A1 CN 2019111416 W CN2019111416 W CN 2019111416W WO 2020237976 A1 WO2020237976 A1 WO 2020237976A1
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rolling
steel
stage
temperature
content
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PCT/CN2019/111416
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English (en)
French (fr)
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陈颜堂
李东晖
党军
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南京钢铁股份有限公司
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Priority to MYPI2021007063A priority Critical patent/MY197582A/en
Publication of WO2020237976A1 publication Critical patent/WO2020237976A1/zh

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    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
    • C21C5/28—Manufacture of steel in the converter
    • C21C5/30—Regulating or controlling the blowing
    • C21C5/35—Blowing from above and through the bath
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C7/10—Handling in a vacuum
    • 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
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/06—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
    • C22C38/14—Ferrous alloys, e.g. steel alloys containing titanium or zirconium

Definitions

  • the invention belongs to the field of low-alloy structural steel manufacturing, and specifically relates to an ultrafine needle-like structure steel and a production method thereof.
  • LPG liquefied petroleum gas
  • existing liquefied petroleum gas (LPG) storage tanks are mostly constructed with low temperature steels such as 07MnNiMoVDR, 09MnNiDR, 16MnDR, etc., and are delivered in normalized or normalized + tempered state.
  • this type of steel has good low-temperature impact toughness, its low-temperature fracture toughness— The crack tip opening displacement (CTOD) is low.
  • low-temperature steels such as 07MnNiMoVDR, 09MnNiDR, 16MnDR, etc. are added with alloying elements such as Ni or expensive alloying elements V and Mo, which are scarce, and the production cost is high.
  • the purpose of the application of the present invention is to provide a cheap ultra-fine needle-like structure steel with excellent low-temperature fracture toughness, which is used to construct steel structures for liquefied petroleum gas storage tanks, ships in polar regions and marine engineering, with a yield strength of ⁇ 420MPa, 40°CCTOD ⁇ 3.5mm, to ensure the safe operation of low-temperature steel structures, and good economic benefits.
  • Chinese invention patent application discloses a "acicular structure high-strength weathering steel and its production method", involving the use of extremely low carbon, Cu-Cr-Ni-
  • the addition of Mo-Nb and the combined addition of two or more of Ti-Al-Zr-RE or Ca will control the carbon content to be close to or less than 0.0218% of the maximum solubility of carbon in ⁇ -Fe at room temperature to reduce Or inhibit the precipitation of cementite and ensure that the main control structure is a uniform acicular structure to obtain excellent weather resistance;
  • the specific components are: C: 0.01-0.04%, Si: 0.15-0.30%, Mn: 1.3-1.6% , P ⁇ 0.03%, S ⁇ 0.01%, Cu: 0.15-0.5%, Cr: 0.2-0.4%, Ni: 0.1-0.24%, Mo: 0.1-0.3%, Nb: 0.03-0.06%, and Ti ⁇ 0.03% , ALs ⁇ 0.035%, Zr ⁇ 0.01% and additional RE ⁇
  • the steel of the present invention is produced by thermomechanical controlled rolling technology + relaxation-precipitation control technology, has excellent weather resistance, excellent low temperature toughness and weldability, no preheating before welding, no heat treatment after welding, and improved welding efficiency It can be widely used in engineering structures such as bridges, buildings, transportation, and offshore platforms.
  • the disadvantage of the patented technology is that there are many alloying elements that need to be controlled for the steel types involved, up to 12 kinds, and it contains expensive alloying elements such as Ni, Mo, Zr, etc.
  • the raw materials are expensive, and the Cu content is 0.15-0.5%.
  • the production process The tendency of moderate hot cracking increases and the yield rate decreases.
  • the rolling process requires thermomechanical control rolling technology + relaxation-precipitation control technology, which is complicated and difficult to control.
  • the Chinese invention patent discloses "non-quenched and tempered acicular structure high-strength low-yield-ratio weathering steel and its production method".
  • the steel grade contains components and their weight percentages: basic Composition: C 0.03 ⁇ 0.08%, Si 0.30 ⁇ 0.60%, Mn 1.30 ⁇ 1.80%, P ⁇ 0.015%, S ⁇ 0.010%, Cu 0.30 ⁇ 0.60%, Ni 0.20 ⁇ 0.50%, Cr 0.40 ⁇ 0.80%, Mo 0.10 ⁇ 0.40%, Nb 0.030 ⁇ 0.080% and Ti ⁇ 0.04%; optional ingredients: AlS ⁇ 0.04% and RE ⁇ 0.40kg/t steel or two or more of Ca ⁇ 0.005%; and the balance Fe It has low welding cold crack sensitivity index, high corrosion resistance index, excellent formability, weather resistance, weldability and low temperature toughness.
  • the technical problem to be solved by the present invention is to provide an ultra-fine needle-like structure steel and a production method thereof in view of the shortcomings of the above prior art.
  • the production cost is low, the production process is easy to control, and the yield rate is high.
  • the technical solution of the present invention to solve the above technical problems is: an ultra-fine needle-like structure steel, the chemical element composition of which by weight percentage includes: C: 0.081 ⁇ 0.11%, Si: 0.10 ⁇ 0.14%, Mn: 1.0 ⁇ 1.29% , P ⁇ 0.008%, S ⁇ 0.002%, Alt: 0.041 ⁇ 0.055%, Ti: 0.041 ⁇ 0.15%, B: 0.0015 ⁇ 0.0030%, the balance is Fe and unavoidable impurities.
  • C Carbon: A certain amount of alloying element C is added to structural steel, and a part of it is dissolved in the Fe matrix to form interstitial solid solution strengthening, which improves the strength of the steel, so that the yield strength of the structural steel of the present invention is ⁇ 420MPa, if C is added If the content is less than 0.081%, the supersaturated solid-soluble C content in the matrix is insufficient, the strengthening effect is insufficient, and the yield strength is difficult to reach the expected; if the C content is higher than 0.11%, Fe 3 C, etc. are easily formed during the production process, which reduces the steel Low-temperature fracture toughness, the constructed low-temperature steel structure is prone to brittle fracture during use, so the C content is set to 0.081 ⁇ 0.11%;
  • Mn manganese: adding an appropriate amount of alloying element Mn to the steel can stabilize the high-temperature austenite structure and reduce the austenite transformation temperature.
  • the manufacturing method of this patent application can inhibit the transformation of austenite into polygonal ferrite and obtain needle-like organization.
  • the content of Mn added in the steel is less than 1.0%, the reduction in the critical temperature of austenite transformation during the production process is not enough to inhibit the formation of massive ferrite, and it is easy to produce massive ferrite + pearlite structure, and it is difficult to obtain super
  • the fine needle-like structure on the one hand, the yield strength of the soft phase structure is lower than 420MPa due to the high ferrite content, on the other hand, it deteriorates the low temperature fracture toughness of the steel; if the Mn content is higher than 1.29%, laths are easily formed during the production process Martensitic structure, too high strength, sharp decrease in toughness, especially low temperature fracture, so the Mn content range is set at 1.0-1.29%;
  • P P is a harmful element in steel, and it is easy to form segregation at the grain boundary, leading to brittle fracture of the grain boundary. Limit P to P ⁇ 0.008%. If the content of P is controlled too low, the smelting cost will be greatly increased. ;
  • S sulfur: The residual element S in structural steel is a harmful element, which reacts with Mn in steel to form flaky inclusions MnS, which splits the matrix and produces microcracks, which sharply reduces the low-temperature fracture toughness of steel.
  • MnS flaky inclusions
  • microcracks microcracks
  • Si silicon: Adding a certain amount of alloying element Si to structural steel can form replacement solid solution strengthening and increase the yield strength of steel, but Si is a ferrite-forming element, which increases the critical temperature of phase transformation of steel, and excessive Si is added It is easy to promote the formation of massive ferrite, and it is difficult to form an ultrafine needle-like structure, so the Si content in the steel is set in the range of 0.10 ⁇ 0.14%;
  • Alt (aluminum): The effect of adding aluminum to steel Alt (full aluminum) can remove oxygen in steel and improve the purity of steel.
  • Al reacts with residual element N in steel to produce AlN, which can effectively refine Microstructure, but if the Al content is too high, it is easy to form the diamond-shaped inclusions Al 2 O 3 and reduce the fracture toughness of the steel. Therefore, the total Alt content in the steel is set in the range of 0.041 to 0.055%;
  • Ti (titanium) the addition of Ti to the steel can react with C and N in the steel to produce Ti (CN) fine particles, which can effectively prevent the movement of grain boundaries, inhibit the growth of grains, and promote the formation of ultra-fine needle-like structures.
  • Ti dissolved in the matrix can inhibit the diffusion of atoms, stabilize austenite, inhibit the transformation of austenite to massive ferrite, and promote the transformation of acicular structure, but if the Ti content is higher than 0.15%, the formed Ti( CN) The precipitated phases are easy to grow up and coarsen, and reduce the low-temperature fracture toughness of the steel, so the Ti content in the steel is set in the range of 0.041 to 0.15%;
  • B boron: adding a small amount of alloying element B to steel can significantly reduce the critical temperature of phase transition, inhibit the formation of high-temperature transformation products-polygonal ferrite, and promote the formation of acicular structure.
  • Part of B segregates at the grain boundary to purify the grain boundary, prevent the harmful elements As and P from segregating at the grain boundary, reduce the brittleness of the grain boundary, and improve the low temperature fracture toughness of the steel.
  • the B content in the steel exceeds 0.0030%, it is easy to The brittle phase BN is formed, which deteriorates the low-temperature fracture toughness of the steel, so the B content in the steel is controlled within the range of 0.0015 to 0.0030%.
  • the present invention further defines the scheme:
  • the aforementioned Ti weight percentage is 0.061 to 0.1%.
  • the aforementioned B weight percentage is 0.0018 to 0.0028%.
  • the aforementioned production method of ultrafine needle-like structure steel specifically includes the following steps:
  • the top-bottom combined blowing converter is filled with deep desulfurization blast furnace molten iron, scrap, MnFe, SiFe, and these alloy materials are smelted, and an oxygen lance is inserted into the upper furnace mouth of the converter to blow in oxygen to raise the furnace temperature to 1630 ⁇ 1720°C for decarburization.
  • the slab is heated first, and the heating temperature is 1180 ⁇ 1240°C, and then soaking is carried out.
  • the soaking temperature is 1200-1220°C, the soaking time is 30-50 minutes, and the slab is in the furnace for ⁇ 4 hours;
  • the first stage of rolling Recrystallization stage of rolling: Before rolling, use high pressure water to remove phosphorus, high pressure water to remove phosphorus 2-3 times, start rolling temperature: 950 ⁇ 1100 °C, 4-6 passes complete the first stage rolling, Pass reduction rate ⁇ 18%,
  • the second stage rolling non-recrystallization stage rolling: After the recrystallization stage is completed, laminar cooling is used to quickly cool the intermediate billet.
  • the temperature of the intermediate billet is lower than 880°C to start the second stage rolling, rolling temperature: 790 ⁇ 880°C, 4-6 passes complete the second stage of rolling, pass reduction rate ⁇ 22%, dephosphorization 1-2 times in high pressure water in the rolling process, and reciprocating 1-3 times by leveler after finishing rolling
  • the aforementioned CaO+FeO addition amount is 3-8% of the molten steel capacity.
  • the aforementioned entire converter smelting time is controlled within 30-50 minutes.
  • the beneficial effects of the present invention are: the steel types involved in the prior patent technology need to control many alloy elements, and contain expensive alloy elements Ni, Mo, Zr, etc., the raw material cost is expensive, and the Cu content: 0.15-0.5%, during the production process
  • the hot cracking tendency increases, the yield rate decreases, and the rolling process requires thermomechanical control rolling technology + relaxation-precipitation control technology.
  • the process is complicated and difficult to control.
  • the steel grade of the present invention has fewer chemical composition control elements and is simple and easy to control. , The production cost is low, the yield rate is high, and the economic benefits are good.
  • the production process of the present invention is simple. After the converter smelted, it undergoes RH vacuum refining.
  • the present invention adopts two-stage controlled rolling of recrystallization and non-recrystallization + controlled cooling to obtain finished steel sheets with ultra-fine needle-like structures. After rolling, the water is quickly cooled and the second is controlled.
  • the fracture toughness is -40°CCTOD ⁇ 3.5mm, and the production process is easy to operate, and the yield rate is high, and the economic benefits are significant. Due to the high strength and good low-temperature fracture toughness, it can be used to construct low-temperature environment steel structural parts to ensure safe operation.
  • Example 1 Example 2, Example 3, Example 4, and Example 5 to verify the chemical composition and The mass percentage content and the influence of the rolling temperature range during the recrystallization stage during the rolling process, the non-recrystallization rolling temperature range, and the controlled cooling temperature range after finishing rolling on the performance parameters
  • three comparative examples were prepared, namely comparative implementation In Example 1, Comparative Example 2 and Comparative Example 3, 8 batches of steel plates were smelted and rolled.
  • the mass percentage content of the chemical components of Comparative Example 1 is not within the scope of the present invention, and the process parameters of the preparation process are within the scope of the present invention, and the mass percentage content of the chemical components of Comparative Example 2 is within the scope of the present invention.
  • the process parameters of the preparation process are not within the scope of the present invention, and the mass percentage content of the chemical components of Comparative Example 3 and the process parameters of the preparation process are not within the scope of the present invention.
  • the chemical element composition weight percentages of the five examples and the three comparative examples are shown in Table 1, where the balance is Fe and unavoidable impurities.
  • the production process control parameters and steel plate quality are shown in Table 2.
  • the yield strength of the steel plate produced by the chemical composition and mass percentage and the rolling temperature controlled by the production process in Examples 1-5 of the present invention are all higher than 420MPa, and the fracture toughness is -40°C CTOD. Higher than 3.5mm.
  • the yield strength of the comparative steel plates produced in Comparative Example 1, Comparative Example 2 and Comparative Example 3 in the steel composition range or/and production process outside the scope of the present invention are lower than 366 MPa, and the -40°C CTOD is lower than 2.1 mm.
  • the yield strength of the steel plate prepared in Example 4 of the present invention is 458 MPa
  • the CTOD at -40°C is 5.2 mm
  • the comprehensive mechanical properties are excellent.
  • the manufacture of ultra-low temperature structural parts can effectively avoid embrittlement and operate safely, which is the best embodiment.
  • the present invention may also have other embodiments. All technical solutions formed by equivalent replacements or equivalent transformations fall within the protection scope of the present invention.

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Abstract

一种超细针状组织结构钢，其化学元素成分按重量百分比包括：C:0.081～0.11％、Si:0.10～0.14％、Mn:1.0～1.29％、P≤0.008％、S≤0.002％、Alt:0.041～0.055％、Ti:0.041～0.15％、B：0.0015～0.0030％，余量为Fe和不可避免的杂质；该超细针状组织结构钢的生产成本较低，生产过程易控制，成材率高。

Description

一种超细针状组织结构钢及其生产方法 技术领域
本发明属于低合金结构钢制造领域，具体涉及一种超细针状组织结构钢及其生产方法。
背景技术
现有液化石油气(LPG)储罐多用07MnNiMoVDR、09MnNiDR、16MnDR等低温钢建造，正火或正火+回火态交货，虽然该类钢材具有良好的低温冲击韧性，但其低温断裂韧性—裂纹尖端张开位移(CTOD)偏低，另一方面，07MnNiMoVDR、09MnNiDR、16MnDR等低温钢中添加了资源短缺的合金元素Ni或价格昂贵合金元素V、Mo等，生产成本较高。本发明申请的目的在于提供一种廉价的低温断裂韧性优良的超细针状组织结构钢，用于建造液化石油气储罐、极地极寒地区船舶及海洋工程用钢结构，屈服强度≥420MPa，40℃CTOD≥3.5mm，保障低温钢结构件安全运行，经济效益良好。
中国发明专利申请(申请号CN200410061112,申请日2004.11.16)公开了一种“针状组织高强度耐候钢及其生产方法”，涉及钢种成分设计上采用极低碳、Cu-Cr-Ni-Mo-Nb的加入及Ti-Al-Zr-RE或Ca中的两种或两种以上复合添加，将碳含量控制在接近或小于常温下碳在α-Fe中的最大溶解度0.0218％，以减少或抑制渗碳体的析出，保证主控组织为均匀的针状组织，以得到优良的耐候性能；具体成分为：C：0.01-0.04％、Si：0.15-0.30％、Mn：1.3-1.6％、P≤0.03％、S≤0.01％、Cu：0.15-0.5％、Cr：0.2-0.4％、Ni：0.1-0.24％、Mo：0.1-0.3％、Nb：0.03-0.06％以及Ti≤0.03％、ALs≤0.035％、Zr≤0.01％和外加RE≤0.4kg/t钢或Ca≤0.005％中的两种或两种以上，余量为Fe和不可表面的夹杂。本发明钢采用热机械控制轧制技术+驰豫-析出控制技术生产，具有优良的耐候性，优异的低温韧性和焊接性，焊前不需预热，焊后不需热处理，提高了焊接效率，可广泛用于桥梁、建筑、交通、海洋平台等工程结构。该专利技术不足之处在于所涉及钢种需控制的合金元素较多，达12种以上，且含昂贵合金元素Ni、Mo、Zr等，原料成本昂贵，含Cu：0.15-0.5％，生产过程中热裂倾向增加，成材率降低，轧制过程需要采用热机械控制轧制技术+驰豫-析出控制技术，工序过程复杂，难于控制。
中国发明专利(申请号CN200910180490,申请日2009.10.16)公开了“非调质针状组织高强度低屈强比耐候钢及其生产方法”，该钢种包含的成分及其重量百分比为：基本成分：C 0.03～0.08％、Si 0.30～0.60％、Mn 1.30～1.80％、P≤0.015％、S≤0.010％、Cu 0.30～0.60％、Ni 0.20～0.50％、Cr 0.40～0.80％、Mo 0.10～0.40％、Nb 0.030～0.080％及Ti≤0.04％；可选成分：AlS≤0.04％及RE≤0.40kg/t钢或Ca≤0.005％中的两种或两种以上；以及余量的Fe和杂质，其焊接冷裂纹敏感性指数低，耐腐蚀指数高，具有优异的成型性、耐候性、焊接性和低温韧性，同时其制备工艺简单，无需热处理，生产周期短， 生产成本低。该专利技术不足之处在于钢中添加了0.3～0.6％的Cu，在批量生产过程中形成Cu致热裂纹，降低了成材率，另外还添加了昂贵合金元素Ni、Mo，增加了生产成本。
发明内容
本发明所要解决的技术问题是，针对以上现有技术存在的缺点，提供一种超细针状组织结构钢及其生产方法，生产成本较低，生产过程易控制，成材率高。
本发明解决以上技术问题的技术方案是：一种超细针状组织结构钢，其化学元素成分按重量百分比包括：C:0.081～0.11％、Si:0.10～0.14％、Mn:1.0～1.29％、P≤0.008％、S≤0.002％、Alt:0.041～0.055％、Ti:0.041～0.15％、B：0.0015～0.0030％，余量为Fe和不可避免的杂质。
本发明中控制的合金元素原理说明如下：
C(碳)：结构钢中添加一定含量的合金元素C，一部分固溶于Fe基体中形成间隙固溶强化，提高钢的强度，使本发明申请结构钢的屈服强度≥420MPa,若添加的C含量低于0.081％,过饱和固溶于基体的C含量不足，强化效果不够，屈服强度难于达到预期；若C含量高于0.11％，则易在生产过程中形成Fe 3C等，降低钢的低温断裂韧性，建造的低温钢结构易在使用过程中发生脆性断裂，故将C的含量设定为0.081～0.11％；
Mn(锰)：钢中添加适量合金元素Mn可稳定高温奥氏体组织，降低奥氏体转变温度，采用本专利申请的制造方法，可抑制奥氏体转变为多边形铁素体，获得针状组织。钢中添加的Mn含量若低于1.0％，生产过程中奥氏体相变临界温度降低量不足于抑制块状铁素体的形成，易产生块状铁素体+珠光体组织，难于获得超细针状组织，一方面因软相组织铁素体含量较多导致屈服强度低于420MPa，另一方面，恶化钢的低温断裂韧性；若Mn含量高于1.29％，生产过程中易生成板条状马氏体组织，强度过高，韧性尤其是低温断裂急剧降低，故将Mn含量范围设定在1.0～1.29％；
P(磷)：钢中P属有害元素，易在晶界处形成偏聚，导致晶界脆性断裂，将P限定在P≤0.008％，若将P含量控制得过低，则大幅增加冶炼成本；
S(硫)：结构钢中残余元素S是有害元素，与钢中Mn反应形成片状夹杂物MnS，割裂基体，产生微裂纹，急剧降低钢的低温断裂韧性，对于要求低温韧性的结构钢，S含量越低越好，但若将S控制得过低，则在冶炼过程中需多次脱硫处理，造成生产成本大幅增加，故将S含量控制在S≤0.002％为宜；
Si(硅)：结构钢中添加一定量的合金元素Si可形成置换固溶强化，提高钢的屈服强度，但Si属铁素体形成元素，提高钢的相变临界温度，加入过高的Si易促使块状铁素体的形成，难于形成超细针状组织，故将钢中的Si含量设定在0.10～0.14％范围；
Alt(铝)：钢中添加铝Alt(全铝)的作用一方面可以祛除钢中氧元素，提高钢的纯净度，另一方面， Al与钢中残余元素N反应生产AlN，可有效细化组织，但若Al含量过高，则易形成菱角状夹杂物Al 2O 3，降低钢的断裂韧性，故将钢中的全Alt含量设定在0.041～0.055％范围；
Ti(钛):钢中加入Ti可与钢中C、N反应生成的Ti(CN)细小颗粒，有效阻止晶界移动，抑制晶粒长大，促使超细针状组织的形成，另一方面，固溶于基体的Ti可抑制原子扩散，稳定奥氏体，抑制奥氏体向块状铁素体的转变,促使针状组织转变，但若Ti含量高于0.15％，则形成的Ti(CN)析出相容易长大、粗化，降低钢的低温断裂韧性，故将钢中的Ti含量设定在0.041～0.15％范围；
B(硼)：钢中加入少量的合金元素B，可显著降低相变临界温度，抑制高温转变产物—多边形铁素体的形成，促使针状组织的形成。部分B偏聚于晶界部位，净化晶界，阻止有害元素As、P等在晶界偏聚，降低晶界脆性，提高钢的低温断裂韧性，但若钢中B含量超过0.0030％，则易形成脆性相BN，恶化钢的低温断裂韧性，故将钢中B含量控制在0.0015～0.0030％范围。
本发明进一步限定方案：
前述的Ti的重量百分比为0.061～0.1％。
前述的B的重量百分比为0.0018～0.0028％。
前述的超细针状组织结构钢的生产方法，具体包括以下步骤：
(1)转炉冶炼
a.顶底复吹转炉装入深脱硫高炉铁水、废钢、MnFe、SiFe这些合金料熔炼，在转炉上部炉口插入氧枪吹入氧气将炉温提升至1630～1720℃，进行脱碳作业，转炉底部吹入氩气搅拌并均匀化钢水，加CaO、FeO脱P，取样检测钢水C含量，当C含量在0.03-0.06％时出钢，如果C含量不在该范围内，继续吹氧脱碳至该成分范围后进行出钢，出钢时间控制在4-9分钟；
(2)RH精炼，钢水处理前，先将浸渍管浸入待处理的钢包钢水中，启动真空系统和冷却水系统，真空槽内压强低于0.7mbar时，保持时间≥12分钟，整体钢水循环次数≥5次；依次加入Al锭、TiFe、BFe，进行合金化钢水，取样分析C、Si、Mn、Alt、Ti和B的含量是否在上述超细针状组织结构钢各成分的范围内，在范围内，处理时间到后进行浇铸，不在范围内，添加碳粉，TiFe，BFe、SiFe、MnFe及Al丝调整至范围内，然后连铸成板坯；
(3)轧制
铸坯先加热，加热温度为1180～1240℃，接着进行均热，均热温度为1200-1220℃，均热时间为30-50分钟，铸坯在炉时间≥4小时；
两阶段完成轧制：
第一阶段轧制：再结晶阶段轧制：轧前采用高压水除磷，高压水除磷2-3次，开轧温度：950～1100℃， 4-6道次完成第一阶段轧制，道次压下率≥18％，
第二阶段轧制：非再结晶阶段轧制：再结晶阶段轧制完成后采用层流冷却浇水快冷中间坯，中间坯温度低于880℃开始第二阶段轧制，轧制温度：790～880℃，4-6道次完成第二阶段轧制，道次压下率≥22％，在轧制过程高压水除磷1-2次，终轧后采用矫直机往复1-3次压平钢板，第二阶段开轧中间坯厚度须满足以下关系式：第二阶段轧制中间坯厚度＝(板坯厚度/2)+18mm；
轧后冷却
轧后浇水快速冷却，返红温度：550～650℃。
前述的CaO+FeO加入量为钢水容量的3～8％。
前述的整个转炉冶炼时间控制在30-50分钟。
本发明的有益效果是：现有专利技术所涉及钢种需控制的合金元素较多，且含昂贵合金元素Ni、Mo、Zr等，原料成本昂贵，含Cu：0.15-0.5％，生产过程中热裂倾向增加，成材率降低，轧制过程需要采用热机械控制轧制技术+驰豫-析出控制技术，工序过程复杂，难于控制，本发明钢种化学成分控制元素较少，简单容易控制操作，生产成本低，成材率高，经济效益好，本发明生产工艺简单，转炉冶炼后经过RH真空精炼，一方面祛除钢中N、H、O等气体；另一方面，通过钢水循环，促使钢中有害大颗粒夹杂充分上浮到钢渣，净化钢水，本发明采用再结晶和非再结晶两阶段控制轧制+控制冷却获得超细针状组织的成品钢板，轧后浇水快速冷，控制第二阶段中间坯厚度＝(板坯厚度/2)+18mm及终轧后返红温度在550～650℃范围以消除钢板生产过程产生的残余应力，可获得优良的综合力学性，屈服强度≥420MPa、断裂韧性-40℃CTOD≥3.5mm，且生产工序过程容易操作，且成材率高，经济效益显著，由于强度高，低温断裂韧性好，可用于建造低温环境钢结构件，能确保安全运行。
具体实施方式
按照本发明化学元素成分、质量百分比及生产方法要求，制备了五个实施例，分别为实施例1、实施例2、实施例3、实施例4、实施例5，为验证各化学组分和质量百分比含量以及轧制过程中的再结晶阶段轧制温度范围、非再结晶轧制温度范围、终轧后的控制冷却温度范围对性能参数的影响，制备了三个对比实施例，即对比实施例1、对比实施例2和对比实施例3，即冶炼并轧制了8批钢板。其中，对比实施例1的化学组分质量百分比含量不在本发明的范围内，而制备过程的工艺参数在本发明的范围内，对比实施例2的化学组分质量百分比含量在本发明的范围内，而制备过程的工艺参数不在本发明的范围内，对比实施例3的化学组分质量百分比含量及制备过程的工艺参数均不在本发明的范围内。五个实施例及三个对比实施例的化学元素成分重量百分比见表1，其中余量为Fe和不可避免的杂质，生产过程控制参数与钢板质量情况见表2。
表1本发明实施例及对比实施例的化学成分对比(wt％)
Figure PCTCN2019111416-appb-000001
表2本发明实施例及对比实施例生产过程控制对钢板性能情况表
Figure PCTCN2019111416-appb-000002
由表1和表2可看出，本发明实施例1-5的化学成分及质量百分比及生产工艺过程控制的轧制温度所生产的钢板屈服强度均高于420MPa，断裂韧性-40℃CTOD均高于3.5mm。而对比实施例1、对比实施例2和对比实施例3的钢成分范围或/和生产工艺不在本发明范围内所生产的对比钢板屈服强度低于366MPa，-40℃CTOD均低于2.1mm。其中，本发明实施例4所制备的钢板的屈服强度为458MPa，-40℃CTOD达 到5.2mm，综合力学性能优良，制造超低温结构件可有效避免脆裂，安全运行，为最佳实施例。
除上述实施例外，本发明还可以有其他实施方式。凡采用等同替换或等效变换形成的技术方案，均落在本发明要求的保护范围。

Claims (6)

  1. 一种超细针状组织结构钢，其特征在于：其化学元素成分按重量百分比包括：C:0.081～0.11％、Si:0.10～0.14％、Mn:1.0～1.29％、P≤0.008％、S≤0.002％、Alt:0.041～0.055％、Ti:0.041～0.15％、B：0.0015～0.0030％，余量为Fe和不可避免的杂质。
  2. 根据权利要求1所述的超细针状组织结构钢，其特征在于：所述Ti的重量百分比为0.061～0.1％。
  3. 根据权利要求1所述的超细针状组织结构钢，其特征在于：所述B的重量百分比为0.0018～0.0028％。
  4. 根据权利要求1-3任意一项所述的超细针状组织结构钢的生产方法，其特征在于：具体包括以下步骤：
    (1)转炉冶炼
    a.顶底复吹转炉装入深脱硫高炉铁水、废钢、MnFe、SiFe这些合金料熔炼，在转炉上部炉口插入氧枪吹入氧气将炉温提升至1630～1720℃，进行脱碳作业，转炉底部吹入氩气并搅拌均匀化钢水，加CaO、FeO脱P，取样检测钢水C含量，当C含量在0.03-0.06％时出钢，如果C含量不在该范围，继续吹氧脱碳至该成分范围后进行出钢，出钢时间控制在4-9分钟；
    (2)RH精炼，钢水处理前，先将浸渍管浸入待处理的钢包钢水中，启动真空系统和冷却水系统，真空槽内压强低于0.7mbar时，保持时间≥12分钟，整体钢水循环次数≥5次，依次加入Al锭、TiFe、BFe，进行合金化钢水，取样分析C、Si、Mn、Alt、Ti和B的含量是否在上述超细针状组织结构钢各成分的范围内，在范围内，处理时间到后进行浇铸，不在范围内，添加碳粉，TiFe，BFe、SiFe、MnFe及Al丝调整至范围内，然后连铸成板坯；
    (3)轧制
    铸坯先加热，加热温度为1180～1240℃，接着进行均热，均热温度为1200-1220℃，均热时间为30-50分钟，铸坯在炉时间≥4小时；
    两阶段完成轧制：
    第一阶段轧制：再结晶阶段轧制：轧前采用高压水除磷，高压水除磷2-3次，开轧温度：950～1100℃，4-6道次完成第一阶段轧制，道次压下率≥18％，
    第二阶段轧制：非再结晶阶段轧制：再结晶阶段轧制完成后采用层流冷却浇水快冷中间坯，中间坯温度低于880℃开始第二阶段轧制，轧制温度：790～880℃，4-6道次完成第二阶段轧制，道次压下率≥22％，在轧制过程高压水除磷1-2次，终轧后采用矫直机往复1-3次压平钢板，第二阶段开轧中间坯厚度须满足以下关系式：第二阶段轧制中间坯厚度＝(板坯厚度/2)+18mm；
    轧后冷却
    轧后浇水快速冷却，返红温度：550～650℃。
  5. 根据权利要求4所述的超细针状组织结构钢的生产方法，其特征在于：所述CaO+FeO加入量为钢水容 量的3～8％。
  6. 根据权利要求4所述的超细针状组织结构钢的生产方法，其特征在于：所述整个转炉冶炼时间控制在30-50分钟。
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CN103343281A (zh) * 2012-10-31 2013-10-09 钢铁研究总院 一种层片状双相高强高韧钢及其制备方法
CN103725956A (zh) * 2013-12-26 2014-04-16 安阳钢铁股份有限公司 一种高强度轻量化自卸车车厢用钢及其生产方法
CN110106442A (zh) * 2019-05-28 2019-08-09 南京钢铁股份有限公司 一种超细针状组织结构钢及其生产方法

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CN113373386A (zh) * 2021-05-22 2021-09-10 江苏铸鸿重工股份有限公司 一种利用废钢制备Cr-Ni-Mo合金钢钢锭的方法
CN113373386B (zh) * 2021-05-22 2024-05-14 江苏铸鸿重工股份有限公司 一种利用废钢制备Cr-Ni-Mo合金钢钢锭的方法
CN115418459A (zh) * 2022-08-26 2022-12-02 河钢股份有限公司 一种钢板的生产方法
CN115418459B (zh) * 2022-08-26 2024-03-22 河钢股份有限公司 一种钢板的生产方法

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