WO2022127192A1 - 一种低合金高强钢q420c钢板及其生产方法 - Google Patents

一种低合金高强钢q420c钢板及其生产方法 Download PDF

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WO2022127192A1
WO2022127192A1 PCT/CN2021/115468 CN2021115468W WO2022127192A1 WO 2022127192 A1 WO2022127192 A1 WO 2022127192A1 CN 2021115468 W CN2021115468 W CN 2021115468W WO 2022127192 A1 WO2022127192 A1 WO 2022127192A1
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steel plate
steel
low
strength
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French (fr)
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刘伟
俞飞
王晓晶
闫文凯
王佩鑫
孙福来
张恭
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天津钢铁集团有限公司
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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
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B1/00—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations
    • B21B1/46—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling metal immediately subsequent to continuous casting
    • B21B1/463—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling metal immediately subsequent to continuous casting in a continuous process, i.e. the cast not being cut before rolling
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B37/00—Control devices or methods specially adapted for metal-rolling mills or the work produced thereby
    • B21B37/74—Temperature control, e.g. by cooling or heating the rolls or the product
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0205—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips of ferrous alloys
    • 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
    • C22C33/00—Making ferrous alloys
    • C22C33/04—Making ferrous alloys by melting
    • C22C33/06—Making ferrous alloys by melting using master alloys
    • 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
    • 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
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/005—Ferrite
    • 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
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/009—Pearlite
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/20—Recycling

Definitions

  • the invention belongs to the technical field of low-alloy high-strength steel production, and in particular relates to a low-alloy high-strength steel Q420C steel plate and a production method for reducing the production cost of the low-alloy high-strength steel Q420C steel plate.
  • Low-alloy high-strength steel plate Q420C is widely used in construction machinery and workshop structural parts production and other fields.
  • the national standard requires that the impact energy of the steel plate be greater than 34J at 0 °C, and the steel plate needs to have good toughness while having high strength.
  • the normal temperature and low temperature structure of Q420C steel plate is generally ferrite + pearlite.
  • a certain amount of microalloys such as Nb, V, and Ti are added to ensure the matching of strength and toughness;
  • the cooling rate and the very low final cooling temperature fully refine the ferrite grains to improve the strength and toughness of the steel plate; or through heat treatment to improve the mechanical properties of the steel plate and increase the toughness and plasticity.
  • the steel plate in the prior art adopts high manganese content Mn: 1.45%-1.55% in the composition design, which will increase the alloy cost, and the use of LF refining and RH refining double refining, and electromagnetic stirring in the continuous casting process will increase the process production cost.
  • the invention provides a production method for reducing the production cost of low-alloy high-strength steel Q420C steel plate.
  • the present invention provides a low-alloy high-strength steel Q420C steel plate and a production method for reducing the production cost of the low-alloy high-strength steel Q420C steel plate.
  • the low-alloy high-strength steel Q420C steel plate contains the following chemical components by mass percentage, and the unit is wt%: C: 0.16-0.20, Si: 0.15-0.30, Mn: 0.70-0.90, P: ⁇ 0.020, S : ⁇ 0.012, Ti: 0.055 ⁇ 0.065, Als: 0.010-0.03, others are Fe and residual elements;
  • the present invention also provides a production method based on reducing the production cost of the above-mentioned low-alloy high-strength steel Q420C steel plate, which sequentially includes converter smelting, LF refining, slab continuous casting, slab heating, high-pressure water descaling, rough rolling, finishing rolling, layer Flow cooling, hot straightening, cooling bed cooling, shearing, sampling, inspection and storage steps; it is characterized in that:
  • the converter smelting process adopts bottom blowing and adopts N-Ar switching mode.
  • the N content in the steel is controlled to be below 40ppm, and the amount of slag in the tapping is controlled to be below 0.01% of the molten steel.
  • the refining time is controlled within 36 minutes.
  • the LF refining ensures the submerged arc temperature rise and reduces the nitrogen absorption during the power supply process. 10-15 minutes before the end of refining, ferrotitanium is added for micro-alloying, and the outbound calcium line is controlled at 200m, divided into 2 Feeding, effectively control the sum of inclusion grades in steel not to exceed grade 1.5;
  • Continuous casting produces slabs with a thickness of 250mm.
  • the superheat of molten steel is controlled within the range of 10-25°C, the pulling speed is controlled at 0.95-1.15m/min throughout the process, and the fluctuation of the liquid level in the mold is controlled within ⁇ 3mm.
  • the secondary cold water adopts weak cooling with a specific water volume of 0.6L/kg;
  • the casting billet is directly sent to the heating furnace, and the hot billet with a thickness of 250mm is heated in the heating furnace for 2.5-3.0 hours;
  • the phosphorus removal by high-pressure water shall be at least one time phosphorus removal to ensure that there is no iron oxide scale on the upper and lower surfaces of the billet;
  • the thickness of the intermediate billet is 85-90mm
  • the control temperature of finishing rolling is 970°C
  • the temperature range of the effluent during the cooling process is controlled at 680-720°C; the straightening times are selected according to the thickness specification and shape of the steel plate, until until leveled.
  • the low-alloy high-strength steel Q420C steel plate production method of the present invention adopts a low-Mn-high-Ti microalloy composition system through reasonable composition design, does not reduce the toughness under the premise of ensuring strength, adopts clean molten steel,
  • the optimized temperature-controlled rolling and ACC-controlled cooling process have obtained the ideal F+P structure, and the grains are uniform and fine.
  • the mechanical properties meet the requirements of GB/T 1591-2018, and the production cost is lower than other iron and steel enterprises that can produce Q420C. Has a strong competitive advantage.
  • Fig. 1 is a picture of a medium and thick plate with a thickness of 16 mm in Example 1;
  • Fig. 2 is the middle and thick plate tissue picture of thickness 20mm in embodiment 2;
  • FIG. 3 is a picture of the medium and thick plate with a thickness of 25 mm in Example 3.
  • FIG. 3 is a picture of the medium and thick plate with a thickness of 25 mm in Example 3.
  • a low-alloy high-strength steel Q420C steel plate contains the following chemical components by mass percentage, the unit is wt%: C: 0.16-0.20, Si: 0.15-0.30, Mn: 0.70-0.90, P: ⁇ 0.020, S: ⁇ 0.012, Ti : 0.055 ⁇ 0.065, Als: 0.010-0.03, others are Fe and residual elements;
  • the invention also provides a production method based on reducing the production cost of the above-mentioned low-alloy high-strength steel Q420C steel plate, which sequentially includes converter smelting, LF refining, slab continuous casting, slab heating, high-pressure water descaling, rough rolling, finishing rolling, layering Flow cooling, hot straightening, cooling bed cooling, shearing, sampling, inspection and storage steps; it is characterized in that:
  • the bottom blowing in the converter smelting process adopts the N-Ar switching mode, the N content in the steel is controlled to be below 40ppm, and the amount of slag under tapping is controlled to be below 0.01% of the molten steel. ;
  • the refining time is controlled within 36 minutes.
  • the LF refining ensures the submerged arc temperature rise and reduces the nitrogen absorption during the power supply process. 10-15 minutes before the end of refining, ferrotitanium is added for micro-alloying, and the outbound calcium line is controlled at 200m, divided into 2 Feeding, effectively control the sum of inclusion grades in steel not to exceed grade 1.5;
  • Continuous casting produces slabs with a thickness of 250mm.
  • the superheat of molten steel is controlled within the range of 10-25°C, the pulling speed is controlled at 0.95-1.15m/min throughout the process, and the fluctuation of the liquid level in the mold is controlled within ⁇ 3mm.
  • the secondary cold water adopts weak cooling with a specific water volume of 0.6L/kg;
  • the casting billet is directly heated to the heating furnace, and the hot billet with a thickness of 250mm is heated in the heating furnace for 2.5-3.0 hours;
  • the phosphorus removal by high-pressure water shall be at least one time phosphorus removal to ensure that there is no iron oxide scale on the upper and lower surfaces of the billet;
  • the thickness of the intermediate billet after rough rolling of the cast slab is required to be 85-90mm, the control temperature of the finishing rolling and rolling is 970°C, and the temperature range of the controlled cooling effluent is controlled at 680-720°C. level up.
  • Examples 1-3 250mm thick large-section continuous casting billet is selected to ensure the compression ratio, and the Q420C finished steel plate with a thickness specification of 16-25mm is produced.
  • the bottom blowing in the converter blowing process adopts N -Ar switching mode, control the N content in the steel to be below 40ppm, control the amount of slag under tapping to be below 0.01% of the amount of molten steel, and it is strictly forbidden to overturn the molten steel after tapping to ensure the purity of the molten steel.
  • the refining time is controlled within 36 minutes, and the LF refining ensures the submerged arc temperature rise and reduces the nitrogen absorption during the power supply process; the lime, aluminum wire, aluminum particles and other white slag are used for desulfurization, and the slag is quickly formed, and the gas volume is reasonably controlled during the desulfurization process. ; 10-15min before the end of refining, add ferro-titanium for micro-alloying, control the outbound calcium line at 200m, feed in 2 times, and control the outbound S to be less than 0.010%; after the composition adjustment is completed, the soft blowing time before sampling is not less than 6min; effectively control the sum of inclusion grades in steel not to exceed grade 1.5.
  • Continuous casting produces slabs with a thickness of 250mm.
  • the superheat of molten steel is controlled within the range of 10-25°C
  • the pulling speed is controlled within 0.95-1.15m/min
  • the fluctuation of the liquid level of the mold is controlled within ⁇ 3mm.
  • the second cold water adopts weak cold water with a specific water volume of 0.6L/kg.
  • the hot billet is sent to the heating furnace, and the heating time of the 250mm thick hot billet in the heating furnace is 2.5-3.0 hours; the high-pressure water dephosphorization adopts one or more passes of descaling to ensure that there is no scale on the upper and lower surfaces of the billet; rough rolling of the billet
  • the thickness of the intermediate billet is required to be 85-95mm, the control temperature of finishing rolling and rolling is 930-970°C, and the temperature range of the controlled cooling water outlet of the steel plate is required to be 680-720°C; the number of straightening times shall be selected according to the thickness specification and shape of the steel plate, until the leveling is completed. until.
  • Table 1 lists the mass percentage and thickness specifications of each element in the steel of Example 1-3; Table 2 lists the controlled rolling + ACC cooling process parameters of Example 1-3; Table 3 lists the production of Example 1-3 The Q420C mechanical properties index.
  • Table 3 shows that the mechanical properties of the Q420C finished steel produced in Examples 1-3 of the present invention fully meet the requirements of the national standard GB/T1591-2018.
  • the low-alloy high-strength steel Q420C steel plate production method of the invention adopts a low-Mn-high-Ti microalloy composition system through reasonable composition design, does not reduce the toughness under the premise of ensuring strength, adopts clean molten steel, optimized temperature-controlled rolling and ACC controlled cooling
  • the process obtains an ideal F+P structure, and the grains are uniform and small, and the mechanical properties can meet the requirements of GB/T1591-2018.
  • the production cost is lower than other iron and steel enterprises that can produce Q420C, and it has a strong competitive advantage.

Abstract

本发明公开了一种低合金高强钢Q420C钢板，该钢板包含如下质量百分比的化学成分，单位为wt％：C:0.16～0.20、Si:0.15～0.30、Mn:0.70～0.90、P:<0.020、S:<0.012、Ti:0.055～0.065、Als:0.010-0.03、其他为Fe和残留元素；本发明还公开一种降低上述低合金高强钢Q420C钢板成本的生产方法，本发明低合金高强钢Q420C钢板生产方法通过合理的成分设计，采用低Mn-高Ti微合金成分体系，在保证强度的前提下不降低韧性，采用洁净钢水、优化控温轧制及ACC控制冷却工艺得到了理想的F+P组织，且晶粒均匀细小，力学性能能够满足GB/T 1591-2018的要求，同时生产成本低于其他可生产Q420C的钢铁企业，具有较强的竞争优势。

Description

一种低合金高强钢Q420C钢板及其生产方法 技术领域
本发明属于低合金高强钢生产技术领域，尤其涉及一种低合金高强钢Q420C钢板及降低低合金高强钢Q420C钢板生产成本的生产方法。
背景技术
低合金高强度钢板Q420C被广泛的应用在工程机械以及厂房结构件制作等领域。国家标准要求钢板0℃时冲击功大于34J，要求钢板在具有较高强度的同时还需要有较好的韧性。Q420C钢板的常温及低温组织一般为铁素体+珠光体，在C-Mn成分基础上添加一定量的Nb、V、Ti等微合金来保证强韧性的匹配；或通过轧后钢板较大的冷却速度和很低的终冷温度充分细化铁素体晶粒来提高钢板强度和韧性；或通过热处理来改善钢板的力学性能，提高韧塑性。
现有技术公开的一种低合金高强度Q420C中厚钢板及其生产方法，其中国专利号CN104018063A申请日期为2014.09.03，该现有技术公开生产厚度在40mm以下的Q420C钢板；该钢板包含如下质量百分比的化学成分(单位，wt％)：C:0.16-1.08、Si:0.35-0.45、Mn:1.45-1.55、P:<0.020、S:<0.015、Als:0.015-0.03、其他为Fe和残留元素；其生产方法为：铁水镁基脱硫、转炉冶炼、LF炉精炼、RH炉处理、连铸采用电磁搅拌和轻压下、铸坯加热、轧制、控冷。该现有技术中的钢板在成分设计上采用高锰含量Mn:1.45％-1.55％会增加合金成本、采用LF精炼和RH精炼双精炼、连铸过程采用电磁搅拌会增加工序生产成本。本发明提供一种降低低合金高强钢Q420C钢板生产成本的生产方法。
发明内容
针对现有技术存在的问题，本发明提供了一种低合金高强钢Q420C钢板及降低低合金高强钢Q420C钢板生产成本的生产方法。
本发明是这样实现的，低合金高强钢Q420C钢板包含如下质量百分比的化学成分，单位为wt％：C:0.16～0.20、Si:0.15～0.30、Mn:0.70～0.90、P:<0.020、S:<0.012、Ti:0.055～0.065、Als:0.010-0.03、其他为Fe和残留元素；
本发明还提供一种基于降低上述低合金高强钢Q420C钢板生产成本的生产方法， 依次包括转炉冶炼、LF精炼、板坯连铸、板坯加热、高压水除鳞、粗轧、精轧、层流冷却、热矫、冷床冷却、剪切、取样、检验以及入库步骤；其特征在于：
转炉冶炼过程采用底吹采用N-Ar切换模式，控制钢中的N含量在40ppm以下，控制出钢下渣量为钢水量的0.01％以下，出钢结束后严禁钢水大翻，确保钢水的洁净度；
LF精炼工艺中精炼时间控制在36min以内，LF精炼保证埋弧升温，减少给电过程吸氮，精炼结束前10-15min加钛铁进行微合金化，出站钙线按照200m控制，分2次喂入，有效控制钢中夹杂物级别总和不超过1.5级；
连铸生产250mm厚的板坯，连铸过程中钢水过热度控制在10-25℃范围内，拉速全程控制在0.95-1.15m/min，结晶器液面波动控制在±3mm以内，使用动态轻压下，二冷水采用弱冷比水量0.6L/kg；
铸坯直接热送到加热炉，250mm厚度的热坯在加热炉中加热时间为2.5-3.0小时；高压水除磷至少采用一道次除磷，保证钢坯上下表面没有氧化铁皮；
铸坯粗轧后中间坯厚度为85-90mm，精轧开轧控制温度为970℃，控冷过程出水温度范围控制在680-720℃；根据钢板厚度规格和板形情况选择矫直次数，直至矫平为止。
本发明具有的优点和技术效果：本发明低合金高强钢Q420C钢板生产方法通过合理的成分设计，采用低Mn-高Ti微合金成分体系，在保证强度的前提下不降低韧性，采用洁净钢水、优化控温轧制及ACC控制冷却工艺得到了理想的F+P组织，且晶粒均匀细小，力学性能满足GB/T 1591-2018的要求，同时生产成本低于其他可生产Q420C的钢铁企业，具有较强的竞争优势。
附图说明
图1是实施例1中厚度为16mm的中厚板组织图片；
图2是实施例2中厚度为20mm的中厚板组织图片；
图3是实施例3中厚度为25mm的中厚板组织图片。
具体实施方式
为了使本发明的目的、技术方案及优点更加清楚明白，以下结合实施例，对本发明进行进一步详细说明。应当理解，此处所描述的具体实施例仅仅用以解释本发明，并不用于限定本发明。
一种低合金高强钢Q420C钢板包含如下质量百分比的化学成分，单位为wt％：C: 0.16～0.20、Si:0.15～0.30、Mn:0.70～0.90、P:<0.020、S:<0.012、Ti:0.055～0.065、Als:0.010-0.03、其他为Fe和残留元素；
本发明还提供一种基于降低上述低合金高强钢Q420C钢板生产成本的生产方法，依次包括转炉冶炼、LF精炼、板坯连铸、板坯加热、高压水除鳞、粗轧、精轧、层流冷却、热矫、冷床冷却、剪切、取样、检验以及入库步骤；其特征在于：
转炉冶炼程底吹采用N-Ar切换模式，控制钢中的N含量在40ppm以下，控制出钢下渣量为钢水量的0.01％以下，出钢结束后严禁钢水大翻，确保钢水的纯净度；
LF精炼工艺中精炼时间控制在36min以内，LF精炼保证埋弧升温，减少给电过程吸氮，精炼结束前10-15min加钛铁进行微合金化，出站钙线按照200m控制，分2次喂入，有效控制钢中夹杂物级别总和不超过1.5级；
连铸生产250mm厚的板坯，连铸过程中钢水过热度控制在10-25℃范围内，拉速全程控制在0.95-1.15m/min，结晶器液面波动控制在±3mm以内，使用动态轻压下，二冷水采用弱冷比水量0.6L/kg；
铸坯直接热送到加热炉，250mm厚度的热坯在加热炉中加热时间为2.5-3.0小时；高压水除磷至少采用一道次除磷，保证钢坯上下表面没有氧化铁皮；
铸坯粗轧后中间坯厚度要求85-90mm，精轧开轧控制温度为970℃，控冷出水温度范围控制在680-720℃；根据钢板厚度规格和板形情况选择矫直次数，直至矫平为止。
请参阅图1至图3，实施例1-3；选用250mm厚大断面连铸坯以保证压缩比，生产厚度规格为16-25mm的Q420C成品钢板，生产过程中转炉吹炼过程底吹采用N-Ar切换模式，控制钢中的N含量在40ppm以下，控制出钢下渣量为钢水量的0.01％以下，出钢结束后严禁钢水大翻，确保钢水的纯净度。LF精炼工艺中精炼时间控制在36min以内，LF精炼保证埋弧升温，减少给电过程吸氮；采用石灰，铝线，铝粒等造白渣脱硫，快速成渣，在脱硫过程中合理控制气量；精炼结束前10-15min加钛铁进行微合金化，出站钙线按照200m控制，分2次喂入，出站S控制在0.010％以下；成分调整完成后取样前软吹时间不低于6min；有效控制钢中夹杂物级别总和不超过1.5级。连铸生产250mm厚的板坯，过程中钢水过热度控制在10-25℃范围内，拉速全程控制在0.95-1.15m/min，结晶器液面波动控制在±3mm以内，使用动态轻压下，二冷水采用弱 冷比水量0.6L/kg。铸坯热送到加热炉，250mm厚度热坯在加热炉中加热时间为2.5-3.0小时；高压水除磷采用一道次或多道次除鳞，保证钢坯上下表面没有氧化铁皮；铸坯粗轧后中间坯厚度要求85-95mm，精轧开轧控制温度为930-970℃，钢板控冷出水温度范围要求在680-720℃；根据钢板厚度规格和板形情况选择矫直次数，直至矫平为止。
表1列出了实施例1-3钢中各元素质量百分比及厚度规格；表2列出了实施例1-3控轧+ACC冷却工艺参数；表3列出了实施例1-3所生产的Q420C力学性能指标。
表1 实施例1-3的主要化学成分质量百分数(wt％)
Figure PCTCN2021115468-appb-000001
表2 实施例1-3的控轧+ACC工艺
Figure PCTCN2021115468-appb-000002
表3 实施例1-3的力学性能
实施例 抗拉强度 屈服强度 延伸率 冷弯 0℃冲击功
1 564 478 26 合格 71
2 549 456 23 合格 66
3 553 439 22 合格 69
表3显示，本发明实施例1-3所生产的Q420C成品钢力学性能完全满足国标GB/T1591-2018的要求。
本发明低合金高强钢Q420C钢板生产方法通过合理的成分设计，采用低Mn-高Ti微合金成分体系，在保证强度的前提下不降低韧性，采用洁净钢水、优化控温轧制及ACC控制冷却工艺得到了理想的F+P组织，且晶粒均匀细小，力学性能能够满足GB/T1591-2018的要求，同时生产成本低于其他可生产Q420C的钢铁企业，具有较强的竞争优势。
以上所述仅为本发明的较佳实施例而已，并不用以限制本发明，凡在本发明的精神和原则之内所作的任何修改、等同替换和改进等，均应包含在本发明的保护范围之内。

Claims (2)

  1. 一种低合金高强钢Q420C钢板；该钢板包含如下质量百分比的化学成分，单位为wt％：C:0.16～0.20、Si:0.15～0.30、Mn:0.70～0.90、P:<0.020、S:<0.012、Ti:0.055～0.065、Als:0.010-0.03、其他为Fe和残留元素；
  2. 基于降低上述低合金高强钢Q420C钢板生产成本的生产方法，依次包括转炉冶炼、LF精炼、板坯连铸、板坯加热、高压水除鳞、粗轧、精轧、层流冷却、热矫、冷床冷却、剪切、取样、检验以及入库步骤；其特征在于：
    转炉冶炼过程底吹采用N-Ar切换模式，控制钢中的N含量在40ppm以下，控制出钢下渣量为钢水量的0.01％以下，出钢结束后严禁钢水大翻，确保钢水的洁净度；
    LF精炼工艺中精炼时间控制在36min以内，LF精炼保证埋弧升温，减少给电过程吸氮，精炼结束前10-15min加钛铁进行微合金化，出站钙线按照200m控制，分2次喂入，有效控制钢中夹杂物级别总和不超过1.5级；
    连铸生产250mm厚的板坯，连铸过程中钢水过热度控制在10-25℃范围内，拉速全程控制在0.95-1.15m/min，结晶器液面波动控制在±3mm以内，使用动态轻压下，二冷水采用弱冷比水量0.6L/kg；
    铸坯直接热送到加热炉，250mm厚度的热坯在加热炉中加热时间为2.5-3.0小时；高压水除磷至少采用一道次除磷，保证钢坯上下表面没有氧化铁皮；
    铸坯粗轧中间坯厚度要求85-90mm，精轧开轧控制温度为970℃，控冷出水温度范围控制在680-720℃；根据钢板厚度规格和板形情况选择矫直次数，直至矫平为止。
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