WO2023165019A1 - 基于全新压下模式改善高碳钢小方坯铸坯均质性的方法 - Google Patents

基于全新压下模式改善高碳钢小方坯铸坯均质性的方法 Download PDF

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WO2023165019A1
WO2023165019A1 PCT/CN2022/092403 CN2022092403W WO2023165019A1 WO 2023165019 A1 WO2023165019 A1 WO 2023165019A1 CN 2022092403 W CN2022092403 W CN 2022092403W WO 2023165019 A1 WO2023165019 A1 WO 2023165019A1
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reduction
carbon steel
electromagnetic stirring
billet
slab
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PCT/CN2022/092403
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English (en)
French (fr)
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高宇波
王郢
包燕平
王敏
桂仲林
廖家明
王向红
张孟昀
沈艳
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中天钢铁集团有限公司
常州中天特钢有限公司
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Publication of WO2023165019A1 publication Critical patent/WO2023165019A1/zh

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/10—Supplying or treating molten metal
    • B22D11/11—Treating the molten metal
    • B22D11/114—Treating the molten metal by using agitating or vibrating means
    • B22D11/115—Treating the molten metal by using agitating or vibrating means by using magnetic fields
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/12—Accessories for subsequent treating or working cast stock in situ
    • B22D11/1206—Accessories for subsequent treating or working cast stock in situ for plastic shaping of strands
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/12—Accessories for subsequent treating or working cast stock in situ
    • B22D11/122—Accessories for subsequent treating or working cast stock in situ using magnetic fields
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/16—Controlling or regulating processes or operations
    • 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

Definitions

  • the invention belongs to the technical field of metallurgy, and in particular relates to a method for improving the homogeneity of high-carbon steel billets based on a new reduction mode.
  • the technical measures usually adopted mainly include low superheat pouring, high-strength secondary cooling and casting speed control, electromagnetic stirring and reduction technology [1-6] .
  • low superheat pouring has extremely high requirements for temperature control in the pouring process, which is likely to cause fluctuations in production flow and pouring stability.
  • High-strength secondary cooling technology and casting speed control can have a positive effect on center segregation, but produce slabs The probability of crack defects is greatly increased, and the production efficiency will also be damaged; after continuous development and improvement of electric stirring technology, especially electromagnetic stirring technology, a high industrial application coverage rate of continuous casting process has been realized, but a single electromagnetic stirring Improvements in internal quality are relatively limited.
  • Continuous casting solidification terminal reduction technology has been widely used in recent years.
  • This technology is generally considered to be an effective method to improve the central segregation and density of continuous casting slabs.
  • this method is mainly applied to large cross-sections of circles [7] and squares. [8,9] and plate [10,11] slabs, there are few reports and applications on billets (below 200mm), the reason is that the improvement effect of light reduction before small sections is not significant, mainly because the liquid core Small, the reduction effect is not easy to grasp, not as obvious as under the condition of large cross-section and large liquid core, so the previous reduction process is mainly used in large cross-section billets.
  • the current reduction technology usually focuses on light reduction before the slab is completely solidified, or only implements heavy reduction at the end of solidification or after complete solidification; at the same time, the setting of the reduction process parameters is
  • the decisive factor affecting the reduction effect is that improper reduction not only fails to improve the internal quality of the slab, but may also cause slab defects such as intensified segregation distribution inside the slab and cracks.
  • the present invention provides a method for improving the homogeneity of high carbon steel billets based on a new reduction mode, innovatively utilizing dynamic light reduction and heavy reduction of billets to effectively combine continuous reduction in the solidification interval and The combination of single-point reduction and further use of the synergistic effect of electromagnetic stirring on the control of the billet structure on this basis has realized the effective improvement of the homogeneity of the high-carbon steel billet.
  • the specific technical solution adopted in order to achieve the purpose of the present invention is: a method for improving the homogeneity of high-carbon steel billets based on a new reduction mode, involving high-carbon steel billet components: C: 0.67-1.0 %, Si: 0.12-0.50%, Mn: 0.02-0.80%, P ⁇ 0.025%, S ⁇ 0.025%, the rest are specific additions of alloys and Fe for various steel types, billet specifications 145-200mm (section side length, preferably The billet section is 175mm*175mm).
  • the billets with a section of 175mm*175mm are poured at a casting speed of 1.6-3.0m/min and under appropriate secondary cooling conditions.
  • the liquid core in the center of the billet still has a good It can carry out horizontal rotation movement under the action of electric stirring, and exert the effect of electric stirring on the uniform composition and temperature of molten steel at the end of solidification, and reduce the accumulation of solute elements in the solidification two-phase area.
  • the electric stirrer adopts alternate stirring, that is, intermittent stirring in reverse direction. On the one hand, the molten steel stirred at the solidification front will not continue to form a regular strong stirring motion, which can avoid the occurrence of "band segregation".
  • the setting of stirring current and frequency is based on the electromagnetic torque generated.
  • the setting range of the electromagnetic stirring electromagnetic torque of the crystallizer is 13-20N ⁇ mm
  • the setting range of the electromagnetic stirring electromagnetic torque of the end electromagnetic stirring is 15-30N ⁇ mm.
  • it can effectively carry out shrinkage, avoid the negative pressure generated by shrinkage to suck and enrich the molten steel to the center of the slab, and reduce the subsequent feeding pressure under heavy pressure;
  • the molten steel is properly refluxed to the liquid phase to redistribute the solute (not too much reflux, otherwise the negative segregation will be aggravated), and at the same time prevent the adverse effects of compression cracks and billet bulging at the solidification front under low central solid phase ratio.
  • the pressure rolls for light reduction are 5-10 pairs of continuously distributed pressure rolls, and the reduction speed range is controlled at 2mm/m-6mm/m.
  • the corresponding first pressure roll is subjected to single-roll heavy reduction, and the reduction is preferably 10-15 mm.
  • the heavy reduction with a large reduction can greatly avoid the risk of cracks in the center of the reduction, and at the same time, it is more beneficial to use the temperature difference between the core and the surface to effectively transfer the reduction to the core of the slab without causing the slab to widen significantly. part, fully press the central shrinkage cavity, and eliminate porosity.
  • the present invention has the following technical advantages:
  • the method of the present invention innovatively carries out dynamic mechanical reduction on the billet, and utilizes the combination of light reduction and heavy reduction, continuous reduction and single-point reduction in a reasonable reduction range, and makes full use of light reduction.
  • the positive effect and superimposed effect of reduction on slab segregation and heavy reduction on slab density have achieved a significant and effective improvement in the internal quality of high carbon steel billets under high production efficiency conditions; while dynamic reduction Implementation and reasonable on-line adjustment of reduction parameters create positive conditions for the stable output of high-quality casting slabs under the conditions of variable steel types, variable temperatures, variable cooling and variable casting speeds, and greatly enhance the steel types and casting of the inventive method.
  • the casting speed during the pouring process is 2.0-2.8m/min
  • the specific water volume is 0.25-1.2L/kg
  • the degree of superheat is 20-35°C.
  • the electromagnetic stirring of the mold and the electromagnetic stirring at the end are turned on.
  • the implementation parameters such as electromagnetic stirring of the mold of various steel types and the electromagnetic torque of the electromagnetic stirring at the end are listed in Table 2.
  • the final stirring is reversible intermittent stirring, and the specific interval is set as 10s-3s-10s, that is, the forward rotation lasts for 10s, the stop is 3s, and the reverse rotation is 10s, so it is a cycle of action.
  • the position of electromagnetic stirring at the end corresponds to the solid fraction fs of the slab center as 0.12, 0.15, 0.13 and 0.18, respectively.
  • Continuous multi-roll dynamic soft reduction (continuous multi-roll internal soft reduction in the range of fs: 04-0.85) is implemented at the end of slab solidification.
  • the relevant parameters of dynamic soft reduction for each representative steel grade are shown in Table 3. Among them, the range of the solid fraction fs corresponding to the slab center in the reduction interval is mainly concentrated in the range of 0.4-0.85, and the corresponding value of the specific steel type is slightly different due to the difference in the distribution of the two-phase zone due to the characteristics of the steel type and the pouring conditions.
  • the total dynamic light reduction increases from 10mm to 16mm with the increase of the carbon content of the representative steel, and the number of roller pairs increases from 5 pairs to 10 pairs. Change between 2-6mm/m.
  • Comparative example 1 Low casting speed without reduction, only electromagnetic stirring, and other parameters are optimized and adjusted
  • the casting speed is 1.6m/min, the specific water volume is 0.56L/kg, and the degree of superheat is 15-20°C.
  • the electromagnetic stirring torque of the mold electromagnetic stirring is 15N ⁇ mm
  • the electromagnetic stirring electromagnetic torque of the end electromagnetic stirring is set at 30N ⁇ mm
  • the final stirring adopts one-way continuous stirring.
  • Comparative example 2 The reduction range covers fs: 0.4 ⁇ fs ⁇ 1, under the heavy pressure of 0.9 ⁇ fs ⁇ 1.0, the other parameters are optimized and adjusted
  • the casting speed is 2.5m/min
  • the specific water volume is 0.25L/kg
  • the degree of superheat is 20-35°C.
  • the electromagnetic stirring moment of the electromagnetic stirring of the mold is 15N ⁇ mm, and the electromagnetic moment of the electromagnetic stirring at the end is set at 23N ⁇ mm.
  • the final stirring adopts intermittent stirring in reverse direction, and the specific interval is set as 10s-3s-10s, that is, the forward rotation lasts for 10s, the stop is 3s, and the reverse rotation is 10s, so it is a cycle of action.
  • the reduction interval corresponds to the solid phase ratio fs of the slab center
  • the range is 0.4-1
  • the range of light reduction is fs: 0.4-0.9
  • the light reduction is 14mm. It is implemented by six sets of continuous pressing rollers, and the reduction rate of this process is 1-5mm/m. Then implement single-point heavy pressing again in the interval of 0.9 ⁇ fs ⁇ 1.0, and the amount of reduction is 7mm.
  • Comparative example 3 The amount of reduction is concentrated on the low fs, and the rest of the parameters are optimized and adjusted
  • the casting speed is 2.6m/min, the specific water volume is 0.60L/kg, and the degree of superheat is 20-35°C.
  • the electromagnetic stirring moment of the electromagnetic stirring of the mold is 15N ⁇ mm, and the electromagnetic moment of the electromagnetic stirring at the end is set at 23N ⁇ mm.
  • the final stirring adopts intermittent stirring in reverse direction, and the specific interval is set as 10s-3s-10s, that is, the forward rotation lasts for 10s, the stop is 3s, and the reverse rotation is 10s, so it is a cycle of action.
  • Dynamic soft reduction and heavy reduction are implemented in sections at the end of the solidification of the slab.
  • the range of light reduction corresponds to the solid phase ratio fs of the slab center is 0.2-0.6, and the light reduction is 14mm.
  • the reduction is carried out by four pairs of rollers. ,
  • Comparative example 4 Do not turn on the electromagnetic stirring, the light reduction is too large, and there is no heavy pressure
  • the casting speed is 2.7m/min
  • the specific water volume is 1.12L/kg
  • the degree of superheat is 20-35°C.
  • the electromagnetic torque of the electromagnetic stirring of the crystallizer is 15N ⁇ mm, and turn off the electromagnetic stirring at the end.
  • the soft reduction interval corresponds to the range of the solid phase ratio fs of the slab center from 0.4 to 0.7, and the light reduction is 32mm. It is carried out by eight sets of continuous pressure rollers. Implementation, the reduction rate of this process is 4.5-8.5mm/m (in this comparative example, the solid phase ratio and reduction rate of the slab center corresponding to the light reduction range are optimized and adjusted based on the large reduction amount).

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  • Mechanical Engineering (AREA)
  • Chemical & Material Sciences (AREA)
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  • Organic Chemistry (AREA)
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Abstract

本发明属于冶金技术领域，具体涉及基于全新压下模式改善高碳钢小方坯铸坯均质性的方法，包括如下步骤：浇铸过程中开启结晶器电磁搅拌及末端电磁搅拌，末端电磁搅拌对应铸坯中心固相率fs＝0.1-0.2，控制拉速1.6-3.0m/min；在铸坯凝固末端实施轻压下，轻压下区间对应铸坯中心固相率fs＝0.4-0.85，压下量为8-16mm，并分配至多辊进行小量多辊连续轻压下操作；在铸坯中心固相率fs为1对应的第一个压辊实施单辊重压下。本发明方法不仅在确保高碳钢小方坯生产高效化下实现了均质化，为节能低耗低成本生产高质量高碳钢铸坯开辟了全新的生产工艺途径，而且也为小方坯生产一火材优质高碳特种钢奠定了重要基础。

Description

基于全新压下模式改善高碳钢小方坯铸坯均质性的方法 技术领域
本发明属于冶金技术领域，具体涉及基于全新压下模式改善高碳钢小方坯铸坯均质性的方法。
背景技术
高碳钢在连铸过程中容易形成严重的芯部宏观偏析、中心疏松、缩孔以及内部裂纹等内部缺陷，这些缺陷的形成将大大降低铸坯的均质性。在不排除后续工序进一步产生不利影响的情况下，这些缺陷若无法通过加热及轧制过程进行消除或得到显著改善，则很可能导致后续轧材出现组织和性能的明显差异或异常，进而在钢材加工过程如拉拔时出现杯锥断裂，抑或在其它使用过程中出现不同的失效问题。
针对于铸坯均质性的改善，通常采用的技术措施主要有低过热度浇注，高强度二冷及拉速控制，电磁搅拌以及压下技术等 [1-6]。这其中，低过热度浇注对于浇注过程温度控制要求极高，易造成生产顺行及浇注稳定性的波动，高强度二冷技术及拉速控制能够对中心偏析等产生积极作用，但产生铸坯裂纹缺陷的几率大幅增加，生产效率也将受损；电搅技术，特别是电磁搅拌技术在经历不断发展及完善后，实现了连铸过程颇高的工业化应用覆盖率，不过单一的电磁搅拌对于内部质量的改善相对有限。
连铸凝固末端压下技术近年来得到了广泛应用，该技术被普遍认为是改善连铸坯中心偏析和致密度的有效方法，而该方法目前主要集中应用于较大断面的圆 [7]、方 [8,9]、板 [10,11]铸坯，在小方坯(200mm以下)上则鲜有报道和应用， 原因在于小断面之前轻压下改善的效果不显著，主要是其液芯小，压下作用不好把握，不如大断面大液芯条件下的明显，所以之前压下工艺主要应用于大断面铸坯。就压下形式而言，当前的压下技术通常侧重于铸坯完全凝固前的轻压下，抑或仅仅在凝固末期或完全凝固后实施重压下；与此同时，压下工艺参数的设置是影响压下效果的决定因素，压下不当不仅起不到改善铸坯内部质量的效果，还可能引起铸坯内部偏析分布加剧及裂纹等铸坯缺陷。
[1]薛正良,李正邦,张家雯.高碳钢连铸方坯中心偏析[J].炼钢，2000.16(1):56-59
[2]王韬,陈伟庆,王宏斌,等.连铸参数和末端电磁搅拌对82B钢小方坯中心碳偏析的影响[J].特殊钢,2013,34(1):49-51
[3]何金平,吴健鹏,王国平.SWRH82B连铸坯中心偏析的改善[J].炼钢.2005.21(3):5-8
[4]贾燕璐,苗锋,赵文成,等.末端电磁搅拌对φ400mm铸坯碳偏析的影响[J].热加工工艺,2012,41(7):61-65
[5]安航航,包燕平,王敏,等.高碳耐磨球钢大方坯连铸过程凝固定律及在轻压下过程中的应用[J].中南大学学报(自然科学版).2018,49(05):1037-1046
[6]赵军普,刘浏,范建文,等.轻压下技术及其在连铸中的研究与应用[J].材料导报.2016,30(15):57-61
[7]曹学欠,王颖,陈杰.大圆坯连铸轻压下有限元分析[J].连铸,2018,43(4):14-16
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[9]李聿军,李亮,兰鹏,等.特殊钢大方坯动态轻压下压下量模型研究[J].连铸,2018,43(4):27-32
[10]孟怀军,邢飞.板坯连铸机辊缝收缩控制技术的探讨和优化[J].宽厚板,2013,19(2):31-35
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发明内容
本发明提供一种基于全新压下模式改善高碳钢小方坯铸坯均质性的方法，创新性的利用小方坯动态轻压下及重压下有效结合，在凝固区间连续压下与单点压下相结合，在此基础上进一步利用电磁搅拌对于铸坯组织控制的协同作用，实现了高碳钢小方坯均质性的有效提高。
为了实现本发明目的所采用的具体技术方案为：基于全新压下模式改善高碳钢小方坯铸坯均质性的方法，涉及高碳钢钢种小方坯成分中：C：0.67-1.0％，Si：0.12-0.50％，Mn：0.02-0.80％，P≤0.025％，S≤0.025％，其余为各钢种具体添加合金及Fe，小方坯规格145-200mm(断面边长，优选铸坯断面为175mm*175mm)。
在拉速1.6-3.0m/min及适当二次冷却条件下对175mm*175mm断面小方坯进行浇注。
浇注过程开启结晶器电磁搅拌(M-EMS)及末端电磁搅拌(F-EMS)，末搅位置对应铸坯中心固相率fs＝0.1-0.2，此时铸坯心部液芯仍具有较好的流动性，能在电搅作用下进行水平旋转运动，发挥电搅对于凝固末端均匀钢液成分及温度，降低凝固两相区溶质元素集聚的作用。电搅采用交替搅拌，即换向间歇式搅拌，一方面这样搅拌在凝固前沿的钢液不会持续形成有规律强搅拌运动，可以避免“带状偏析”出现，同时搅拌间歇有利于柱状晶恢复继续生长，控制产生过大等轴晶占比，进而避免等轴晶占比过大导致的收缩量大、枝晶粗，以及枝晶塌缩产 生严重V形偏析的不利影响。
搅拌电流及频率的设定以产生电磁力矩为准，作为优选，结晶器电磁搅拌电磁力矩设定范围为13-20N·mm，末端电磁搅拌电搅拌电磁力矩设定范围15-30N·mm。
在铸坯凝固末端实施轻压下，压下区间对应铸坯中心固相率fs＝0.4-0.85，压下量为8-16mm，并分配至多辊进行小量多辊连续轻压下操作。一方面有效进行补缩，避免收缩产生的负压抽吸富集钢液至铸坯中心，减轻后续重压下的补缩压力，另一方面促使铸坯中心区域枝晶间富含溶质元素的钢液适当回流至液相重新进行溶质分配(不能过大程度的回流，否则负偏析加重)，同时防止低中心固相率下凝固前沿产生压下裂纹及铸坯鼓肚带来的不利影响。
作为优选，实施轻压下的压辊为5-10对连续分布的压辊，压下速率范围控制在2mm/m-6mm/m。
随后，在铸坯中心固相率fs为1即完全凝固之后对应的第一个压辊实施单辊重压下，压下量优选为10-15mm。此时进行较大压下量的重压下既可大大规避产生压下中心裂纹的风险，同时更利于利用芯表温差，在不引起铸坯明显增宽下将压下有效传递至铸坯心部，充分压合中心缩孔，消除疏松。
与现有技术相比，本发明具有如下技术优势：
本发明方法创新性的在小方坯上进行动态机械压下，利用轻压下与重压下相结合，连续压下与单点压下在合理压下区间的组合压下方式，充分利用轻压下对于铸坯偏析及重压下对于铸坯致密度的积极作用及叠加效应，实现了高碳钢小方坯铸坯在高生产效率条件下内部质量的大幅有效提升；而动态压下的实施及压下参数的合理在线调整则为变钢种、变温度、变冷却及变拉速浇注条件下 高质量铸坯的稳定输出创造了积极条件，大大增强了该发明方法的钢种及浇注条件适用性；此外，利用电磁搅拌在铸坯内部组织控制方面的协同作用，进一步增强铸坯芯部均质化的控制与提升；最终实现高碳钢小方坯铸坯中心偏析指数稳定控制在1.08以内，中心致密度方面，无明显可见缩孔及大范围疏松，铸坯表面及内部无明显肉眼可见裂纹。不仅在确保高碳钢小方坯生产高效化下实现了均质化，为节能低耗低成本生产高质量高碳钢铸坯开辟了全新的生产工艺途径，而且也为小方坯生产一火材优质高碳特种钢奠定了重要基础。
具体实施方式
本发明不局限于下列具体实施方式，本领域一般技术人员根据本发明公开的内容，可以采用其他多种具体实施方式实施本发明的，或者凡是采用本发明的设计结构和思路，做简单变化或更改的，都落入本发明的保护范围。需要说明的是，在不冲突的情况下，本发明中的实施例及实施例中的特征可以相互组合。
本发明下面结合实施例作进一步详述：
对于上述各代表钢种，浇注实施过程拉速2.0-2.8m/min，比水量为0.25-1.2L/kg，过热度20-35℃，各钢种具体对应浇注基础参数如表1所示。
浇注过程开启结晶器电磁搅拌和末端电磁搅拌，各钢种结晶器电磁搅拌及末端电磁搅拌电磁力矩等实施参数如表2所列。其中末搅均采用换向间歇搅拌，具体间隔设置为10s-3s-10s，即正向旋转持续10s，停止3s，反向旋转10s，如此为一循环作用周期。末端电磁搅拌作用位置对应铸坯中心固相率fs分别为0.12、0.15、0.13和0.18。
在铸坯凝固末端实施连续多辊动态轻压下(fs：04-0.85范围内连续多辊内轻压下)，各代表钢种动态轻压下相关参数如表3所示。其中压下区间对应铸坯中心固相率fs范围主要集中在0.4-0.85，具体钢种对应值由于钢种特性及浇注条 件导致两相区分布差异而稍有不同。总动态轻压下量随代表钢种碳含量增加而从10mm递增至16mm，压辊对数由5对增加至10对，轻压下区间压下率因各辊压下量及辊间距差异而在2-6mm/m间变动。
在各钢种浇注过程铸坯完全凝固即fs＝1后的第一个辊再次实施单点重压下，各代表钢种压下量为10-15mm。
表1基础连铸实施参数
Figure PCTCN2022092403-appb-000001
表2电磁搅拌实施参数
Figure PCTCN2022092403-appb-000002
表3全新组合压下模式实施参数
Figure PCTCN2022092403-appb-000003
Figure PCTCN2022092403-appb-000004
在上述实施条件下，各代表钢种铸坯均质化指标检验结果如表4所示。由此表可知，实施后175mm*175mm小方坯五点钻屑法对应中心偏析指数均控制在1.08以内，依据YB/T153-2015标准进行均一性评级，中心疏松不超过0.5级，未发现中心缩孔，鲜有各种内部裂纹出现，且最大级别不超过0.5级。
表4实施例铸坯均质性质量指标
Figure PCTCN2022092403-appb-000005
*五点法铸坯横剖样钻样，Ф5mm钻屑碳硫分析，偏析指数＝中心点C含量/本体C含量均值
#执行标准YB/T153-2015
对比例1：低拉速无压下，仅电磁搅拌，其余参数为优化调整后的
钢种成分：C：0.72％，Si：0.23％，Mn：0.56％，P：0.011％，S：0.009％， 其余为Fe。
浇注过程拉速1.6m/min，比水量为0.56L/kg，过热度15-20℃。
开启结晶器电磁搅拌和末端电磁搅拌，结晶器电磁搅拌电磁力矩为15N·mm，末端电磁搅拌电磁力矩设定为30N·mm，末搅采用单向连续搅拌。末端电磁搅拌作用位置对应铸坯中心固相率fs＝0.35。
对比例2：压下范围涵盖fs：0.4≤fs＜1，在0.9≤fs＜1.0重压下，其余参数为优化调整后的
钢种成分：C：0.82％，Si：0.25％，Mn：0.68％，P：0.022％，S：0.010％，其余为Fe。
浇注过程拉速2.5m/min，比水量为0.25L/kg，过热度20-35℃。
开启结晶器电磁搅拌和末端电磁搅拌，结晶器电磁搅拌电磁力矩为15N·mm，末端电磁搅拌电磁力矩设定为23N·mm。末搅采用换向间歇搅拌，具体间隔设置为10s-3s-10s，即正向旋转持续10s，停止3s，反向旋转10s，如此为一循环作用周期。末端电磁搅拌作用位置对应铸坯中心固相率fs＝0.15。
在铸坯凝固末端连续实施动态轻压下和重压下(在fs：0.2-0.9内轻压下，又连续在0.9-1.0内重压下)，压下区间对应铸坯中心固相率fs范围为0.4-1，轻压下作用区间为fs：0.4-0.9，轻压下量为14mm，通过六组连续的压辊进行实施，该过程压下率为1-5mm/m。随后在0.9≤fs＜1.0区间再次实施单点重压下，压下量为7mm。
对比例3：压下量集中在低fs，其余参数为优化调整后的
钢种成分：C：0.86％，Si：0.22％，Mn：0.54％，P：0.014％，S：0.009％， 其余为Fe。
浇注过程拉速2.6m/min，比水量为0.60L/kg，过热度20-35℃。
开启结晶器电磁搅拌和末端电磁搅拌，结晶器电磁搅拌电磁力矩为15N·mm，末端电磁搅拌电磁力矩设定为23N·mm。末搅采用换向间歇搅拌，具体间隔设置为10s-3s-10s，即正向旋转持续10s，停止3s，反向旋转10s，如此为一循环作用周期。末端电磁搅拌作用位置对应铸坯中心固相率fs＝0.15。
在铸坯凝固末端分段实施动态轻压下和重压下，轻压下区间对应铸坯中心固相率fs范围为0.2-0.6，轻压下量为14mm，通过四对辊进行压下实施，该过程压下率为2.5-5mm/m，压下量分配和压下率是基于低中心固相率优化调整后的。随后在完全凝固fs＝1之后再次实施单点重压下，压下量为14mm。
对比例4：不开电磁搅拌，过大轻压下量，无重压下
钢种成分：C：0.92％，Si：0.24％，Mn：0.33％，Cr：0.27％，P：0.021％，S：0.016％，其余为Fe。
浇注过程拉速2.7m/min，比水量为1.12L/kg，过热度20-35℃。
开启结晶器电磁搅拌，结晶器电磁搅拌电磁力矩为15N·mm，关闭末端电磁搅拌。
在铸坯凝固末端实施较大压下量的动态轻压下，轻压下区间对应铸坯中心固相率fs范围为0.4-0.7，轻压下量为32mm，通过八组连续的压辊进行实施，该过程压下率为4.5-8.5mm/m(本对比例中轻压下区间对应铸坯中心固相率和压下率均是基于大压下量优化调整的)。
未实施完全凝固后的重压下。
表5对比例铸坯均质性质量指标
Figure PCTCN2022092403-appb-000006
*五点法铸坯横剖样钻样，Ф5mm钻屑碳硫分析，偏析指数＝中心点C含量/本体C含量均值
#执行标准YB/T153-2015
由表5可知，在对比例条件下，铸坯中心偏析明显上升，正偏析均在1.13及以上，最高达到了1.21，而且出现了低中心固相率fs下过大压下量导致的中心负偏析；在芯部致密度方面，仍存在不同程度的中心疏松，甚至还出现了明显的中心缩孔；而就内部裂纹而言，不同对比例中的压下不当导致了不同部位出现了不同程度的内部裂纹。
以上所述，仅为本发明较佳的具体实施方式，但本发明的保护范围并不局限于此，任何熟悉本技术领域的技术人员在本发明揭露的技术范围内，根据本发明的技术方案及其构思加以等同替换或改变，都应涵盖在本发明的保护范围之内。

Claims (7)

  1. 基于全新压下模式改善高碳钢小方坯铸坯均质性的方法，其特征在于：小方坯质量组分中：C：0.67-1.0％，Si：0.12-0.50％，Mn：0.02-0.80％，P≤0.025％，S≤0.025％，其余为具体添加的合金及Fe；包括如下步骤：
    浇铸过程中开启结晶器电磁搅拌及末端电磁搅拌，末端电磁搅拌对应铸坯中心固相率fs＝0.1-0.2，控制拉速1.6-3.0m/min；
    在铸坯凝固末端实施轻压下，轻压下区间对应铸坯中心固相率fs＝0.4-0.85，压下量为8-16mm，并分配至多辊进行小量多辊连续轻压下操作；
    在铸坯中心固相率fs为1对应的第一个压辊实施单辊重压下。
  2. 根据权利要求1所述的基于全新压下模式改善高碳钢小方坯铸坯均质性的方法，其特征在于：结晶器电磁搅拌电磁力矩设定范围为13-20N·mm，和/或末端电磁搅拌电搅拌电磁力矩设定范围15-30N·mm。
  3. 根据权利要求1所述的基于全新压下模式改善高碳钢小方坯铸坯均质性的方法，其特征在于：实施轻压下的压辊为5-10对连续分布的压辊，压下速率范围控制在2mm/m-6mm/m。
  4. 根据权利要求1所述的基于全新压下模式改善高碳钢小方坯铸坯均质性的方法，其特征在于：单辊重压下量为10-15mm。
  5. 根据权利要求1所述的基于全新压下模式改善高碳钢小方坯铸坯均质性的方法，其特征在于：浇铸过程中控制拉速2.0-2.8m/min。
  6. 根据权利要求1所述的基于全新压下模式改善高碳钢小方坯铸坯均质性的方法，其特征在于：浇铸过程中比水量为0.25-1.2L/kg，过热度20-35℃。
  7. 根据权利要求1至6中任一项所述的基于全新压下模式改善高碳钢小方坯铸坯均质性的方法，其特征在于：小方坯铸坯断面为175mm*175mm。
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