CN116640995A - 一种薄规格高精度440MPa级高扩孔酸洗汽车钢及生产方法 - Google Patents
一种薄规格高精度440MPa级高扩孔酸洗汽车钢及生产方法 Download PDFInfo
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- 239000010959 steel Substances 0.000 title claims abstract description 62
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 26
- 238000005406 washing Methods 0.000 title claims abstract description 17
- 239000002253 acid Substances 0.000 claims abstract description 13
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 10
- 239000012535 impurity Substances 0.000 claims abstract description 8
- 238000005096 rolling process Methods 0.000 claims description 78
- 238000005266 casting Methods 0.000 claims description 33
- 230000009467 reduction Effects 0.000 claims description 27
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- 238000010438 heat treatment Methods 0.000 claims description 17
- 238000001816 cooling Methods 0.000 claims description 15
- 230000006698 induction Effects 0.000 claims description 10
- 229910052748 manganese Inorganic materials 0.000 claims description 7
- 229910052719 titanium Inorganic materials 0.000 claims description 7
- 229910052698 phosphorus Inorganic materials 0.000 claims description 5
- 229910052757 nitrogen Inorganic materials 0.000 claims description 4
- 239000000126 substance Substances 0.000 abstract description 8
- 229910052742 iron Inorganic materials 0.000 abstract description 7
- 230000002829 reductive effect Effects 0.000 abstract description 5
- 239000000047 product Substances 0.000 description 34
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 15
- 238000000034 method Methods 0.000 description 14
- 229910001566 austenite Inorganic materials 0.000 description 12
- 239000010936 titanium Substances 0.000 description 12
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- 230000008569 process Effects 0.000 description 10
- 229910000859 α-Fe Inorganic materials 0.000 description 6
- 230000000694 effects Effects 0.000 description 5
- 238000005098 hot rolling Methods 0.000 description 5
- 239000002244 precipitate Substances 0.000 description 5
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 4
- 238000005097 cold rolling Methods 0.000 description 4
- 238000005336 cracking Methods 0.000 description 4
- 230000007547 defect Effects 0.000 description 4
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- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 description 2
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 2
- 238000000137 annealing Methods 0.000 description 2
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- 230000035882 stress Effects 0.000 description 2
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 1
- 229910000746 Structural steel Inorganic materials 0.000 description 1
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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
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- 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
- B21B1/22—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 plates, strips, bands or sheets of indefinite length
- B21B1/24—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 plates, strips, bands or sheets of indefinite length in a continuous or semi-continuous process
- B21B1/26—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 plates, strips, bands or sheets of indefinite length in a continuous or semi-continuous process by hot-rolling, e.g. Steckel hot mill
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- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
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- B21B3/00—Rolling materials of special alloys so far as the composition of the alloy requires or permits special rolling methods or sequences ; Rolling of aluminium, copper, zinc or other non-ferrous metals
- B21B3/02—Rolling special iron alloys, e.g. stainless steel
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- 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
- B21B37/58—Roll-force control; Roll-gap control
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- 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
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- 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
- B21B37/76—Cooling control on the run-out table
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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
- B22D11/001—Continuous casting of metals, i.e. casting in indefinite lengths of specific alloys
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- B—PERFORMING OPERATIONS; TRANSPORTING
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- 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
- B22D11/20—Controlling or regulating processes or operations for removing cast stock
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- 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
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- 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
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- C21—METALLURGY OF IRON
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- 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
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- 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
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- C23G—CLEANING OR DE-GREASING OF METALLIC MATERIAL BY CHEMICAL METHODS OTHER THAN ELECTROLYSIS
- C23G1/00—Cleaning or pickling metallic material with solutions or molten salts
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- C23G1/08—Iron or steel
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- 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
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Abstract
本发明公开了一种薄规格高精度440MPa级高扩孔酸洗汽车钢,其主要化学成分包括Fe、C、Si、Mn等元素,其余为残余元素,按质量百分比计为:C 0.04‑0.065%,Si0.05~0.2%,Mn 0.5~0.9%,Ti 0.02~0.05%,P≤0.015%,S≤0.005%,N≤0.005%,其余为Fe以及不可避免的杂质。本发明产品抗拉强度≥440MPa,屈服强度≥305MPa,产品伸长率≥35%,扩孔率≥125%,厚度波动≤±15μm,可解决了现有440MPa级汽车酸洗钢扩孔、翻边等成形性能不足,≤1.6mm薄规格高精度产品生产受限的关键技术瓶颈,实现“以酸代冷”,不仅为用户降低采购成本,也为汽车产业链的环保升级提供解决之道。
Description
技术领域
本发明属于带钢生产技术领域,尤其涉及一种薄规格高精度440MPa级高扩孔酸洗汽车钢及生产方法。
背景技术
440MPa级高扩孔汽车结构钢广泛地应用于汽车底盘、车身零部件,零件在成形过程中需要进行翻边、扩孔,要求具有一定的扩孔率,同时零件在服役过程中需要承受一定的载荷,要求抗拉强度≥440MPa,材料扩孔率越高,在进行翻边、扩孔成型时,开裂风险越小。
酸洗钢是介于热轧产品和冷轧产品之间的一类产品,通过热轧调控组织性能、尺寸精度,随后通过酸洗去除表面氧化铁皮,获得与冷轧产品相近的表面质量和力学性能。与冷轧产品相比,酸洗钢不经过冷轧所需的冷轧和退火工序,生产流程短,成本低,能有效降低用户的采购成本。由于酸洗工序无法对产品厚度和厚度精度进行改善,受限于热轧机组轧制能力,目前酸洗材仅能提供厚度>1.6mm、厚度精度要求不高的产品,高精度、≤1.6mm薄规格高扩孔钢仍需经过冷轧和退火工序,导致能源消耗高、制造成本高。
CN200710093966.4公开了一种抗拉强度为440MPa级热轧高扩孔钢板,包括以下化学成分(wt%):C:0.01~0.06%、Si:0~0.6%、Mn:0.8~1.3%、P≤0.035%、S≤0.010%、Al:0.025~0.060%、N≤0.0060%、Nb:0~0.25%、其余是Fe和不可避免的杂质;其典型生产工艺为:卷取温度为560~660℃,加热温度为1150~1250℃,热轧轧制变形量大于80%,终轧温度为830~900℃,层流冷却速度为20℃/s。该工艺生产的440MPa级热轧高扩孔钢板延伸率为28~34%,扩孔率为103~113%。但该热轧高扩孔钢板产品的延伸率、扩孔率均较低,存在成形开裂风险,且产品的厚度精度不明确。
CN201310628175.2)开了一种抗拉强度440MPa级热轧高扩孔钢板及其制造方法,其化学成分重量百分比为:C:0.05~0.1%、Si:0.1~0.6%、Mn:0.9~1.8%、P≤0.02%、S≤0.005%、Al:0.015~0.060%、Ca<0.0050%,其余为Fe和不可避免的杂质;其中,([C]×[Mn])≤0.1,([P]+10[S])≤0.04,获得的钢板厚度为1.6~6.0mm,钢板强度与扩孔率乘积TSxλ≥44000MPa%,可以满足汽车工业底盘及复杂冲压件用钢需求,产品扩孔率为100~126%。但是,该热轧高扩孔钢板产品的扩孔率较低,存在成形开裂风险,且产品的厚度精度不明确。
CN201610556820.8公开了一种抗拉强度为440MPa级高表面质量汽车用热轧酸洗钢,其组分及wt%为:C:0.090~0.120%,Si≤0.080%,Mn:1.100~1.500%,P≤0.025%,S≤0.006%,Als:0.015~0.040%;生产方法为:常规冶炼并连铸成坯;对铸坯加热;热轧;卷取;层流冷却;酸洗工艺。该发明利用冷轧酸轧联机生产线的富余产能生产汽车用热轧酸洗钢,利用五机架的最后一个机架对酸洗钢的表面粗糙度进行控制,使产品的表面粗糙度在0.4~1.0μm。该发明的产品扩孔率不明确,且成份设计中碳含量较高,对磷化性能和扩孔性能都不利,并且该发明利用五机架连轧机对表面粗糙度进行控制,生产流程长,成本高。
发明内容
本发明所要解决的技术问题是针对上述现有技术存在的不足而提供一种薄规格高精度440MPa级高扩孔酸洗汽车钢及生产方法,产品抗拉强度≥440MPa,屈服强度≥305MPa,产品伸长率≥35%,扩孔率≥125%,厚度波动≤±15μm,可解决了现有440MPa级汽车酸洗钢扩孔、翻边等成形性能不足,≤1.6mm薄规格高精度产品生产受限的关键技术瓶颈,实现“以酸代冷”,不仅为用户降低采购成本,也为汽车产业链的环保升级提供解决之道。
本发明为解决上述提出的问题所采用的技术方案为:
一种薄规格高精度440MPa级高扩孔酸洗汽车钢,其主要化学成分包括Fe、C、Si、Mn等元素,其余为残余元素,按质量百分比计为:C 0.04~0.065%,Si 0.05~0.2%,Mn0.5~0.9%,Ti 0.02~0.05%,P≤0.015%,S≤0.005%,N≤0.005%,其余为Fe以及不可避免的杂质。
优选地,所述薄规格高精度440MPa级高扩孔酸洗汽车钢,按质量百分比计为:C0.04~0.055%,Si 0.08~0.13%,Mn 0.5~0.7%,P≤0.012%,S≤0.003%,Ti 0.03~0.04%,N≤0.004%,其余为Fe以及不可避免的杂质。在这个优选化学成分范围下,产品抗拉强度为455~480MPa,屈服强度为325~350MPa,产品伸长率≥37%,扩孔率≥135%。
优选地,所述薄规格高精度440MPa级高扩孔酸洗汽车钢的厚度为0.8~1.6mm,厚度波动≤±15μm。
本发明还提供一种上述薄规格高精度440MPa级高扩孔酸洗汽车钢的生产方法,主要包括铸坯浇铸、粗轧、感应加热、精轧、层流冷却、卷取、酸洗等步骤。该生产方法的特点在于:
(8)铸坯浇铸:铸坯拉速为5.5~7m/min,铸坯厚度为90~130mm;
(9)粗轧:将铸坯全连续粗轧至中间坯,中间坯厚度为9~20mm,粗轧单道次压下率50~65%;
(10)感应加热:采用感应加热将中间坯温度升至1160~1220℃;
(11)精轧:采用F1-F5精轧机组,将中间坯以全连续方式轧制至所需产品厚度,产品厚度为0.8~1.6mm,轧制道次为5道次,F1~F2压下率为40~60%,F3压下率为25~40%,其余道次(即F4~F5)压下率为10%~35%,F5轧制速度为6~14m/s,终轧温度为840~880℃;
(12)层流冷却:冷却速度为30~70℃/s;
(13)卷取:卷取温度控制为550~590℃;
(14)酸洗:采用常规酸洗工艺进行酸洗,得到薄规格高精度440MPa级高扩孔酸洗汽车钢。
优选地,铸坯拉速为6~7m/min,铸坯厚度为90~110mm;
优选地,中间坯厚度为9~15mm,粗轧单道次压下率58~65%。
优选地:产品厚度为0.8~1.2mm,轧制道次为5道次,F1~F2压下率为50~60%,F3压下率为33~40%,其余道次(即F4~F5)压下率为20~35%,F5轧制速度为10~14m/s,终轧温度为840~860℃。
本发明基于如下理由选择合金种类及其含量:
C:固溶C会使钢的屈服强度和抗拉强度提高,但会使钢材塑性和扩孔性能降低,同时当碳含量超过0.065%时,凝固过程中可能会发生包晶反应,在浇铸薄板坯时容易产生纵裂和漏钢缺陷,为平衡力学性能和生产难度,本发明控制钢中C重量百分含量为0.04-0.065%。
Si:Si元素也可以提高钢的强度,但Si含量过高时容易在基体和铁皮界面处生成液态Fe2SiO4,增加铁皮的黏附力、造成精轧除鳞困难,而Si含量过低时,轧制过程中氧化铁皮生长速度过快,铁皮氧化应力和热应力较大,铁皮易鼓泡、粉碎,压入钢基造成麻点缺陷。综合考虑表面质量,Si重量百分含量控制为0.05-0.2%。
Mn:Mn固溶于铁素体和奥氏体中,可提高屈服强度和抗拉强度,但Mn提高强度作用不如碳,为提高产品的屈服和抗拉强度需添加大量的锰,将使塑性下降,同时会促进珠光体组织的生成,对扩孔率不利,为使抗拉强度≥440MPa,同时获得较高的扩孔率,综合考虑,Mn重量百分含量控制为0.5~0.9%。
Ti:钛的析出物TiC可以抑制奥氏体和铁素体晶粒长大,通过细化晶粒既可以提高强度,也能提高扩孔率,但Ti含量过高将导致Ti析出物较多,会降低材料的塑性,综合考虑,Ti重量百分比控制为0.02~0.05%。
P:P是钢中有害的杂质元素,钢中P易在钢中形成偏析,降低钢的韧性和焊接性能,故P含量越低越好,综合考虑,P含量≤0.015%。
S:S会与Ti结合形成TiS或Ti4C2S2,但由于析出温度较高,析出物较粗大,无法有效抑制晶粒长大,反而会消耗形成TiC析出物的Ti,导致强化作用减弱,因此,钢中S含量≤0.005%。
N:N与Ti结合力较强,会在液相中析出粗大的TiN,一方面会消耗形成TiC析出物的Ti,导致强化作用减弱,另一方面,粗大的TiN在扩孔过程中会形成应力集中,导致扩孔率降低,因此,钢中N含量≤0.005%。
本发明所述薄规格高精度440MPa级高扩孔酸洗汽车钢的生产方法,技术上存在以下特点:
本发明之所以控制铸坯厚度90~130mm,铸坯拉速为5.5~7m/min,是为了提高铸坯冷却速度,形成细小弥散的夹杂物,抑制奥氏体晶粒粗化。
本发明之所以控制中间坯厚度为9~20mm,单道次压下率50~65%,是为了通过高温大压下,使铸态粗大的奥氏体充分再结晶,形成细小的奥氏体晶粒,同时,可以促进TiC粒子在轧制过程中动态析出,抑制奥氏体晶粒长大,有利于细化室温组织、提高强度和扩孔率。
本发明之所以采用感应加热将中间坯温度升至1160~1220℃,主要是为了降低降低精轧负荷,中间坯温度过低导致精轧负荷较高,轧制力过大、危害板形,但中间坯温度过高可能导致TiC粒子回溶,使得抑制奥氏体晶粒长大作用减弱。
本发明控制精轧轧制道次为5道次,F1~F2压下率为50~60%,F3压下率为30~45%,其余道次压下率为10%~35%,在精轧F1~F2道次,进一步促进奥氏体再结晶和TiC粒子析出,细化奥氏体晶粒,F3、F4、F5压下率控制主要是为了获得所需产品厚度,同时提高厚度精度和板形质量。精轧步骤中,控制F5轧制速度为6~14m/s,轧制速度过高或过低都无法实现全连续轧制,全连续轧制无需穿带、抛钢,温度均匀、压下率稳定,使得轧制薄规格产品时稳定性高、厚度精度高。精轧步骤中,终轧温度为840~880℃,若终轧温度高于880℃时将导致奥氏体晶粒内部促进冷却过程中形核的变形带、位错、空位等缺陷数量少,铁素体形核核心数量少会使得室温组织粗大,不利于强度和扩孔率的提高,终轧温度低于840℃时,会使得尾部机架轧制负荷高,不利于厚度精度和板形质量。
本发明之所以控制层流冷却速度为30~70℃/s,卷取温度550~590℃,是为了降低铁素体转变温度、减少珠光体组织的生成,获得均匀、细小的铁素体组织,提高强度和扩孔率。
与现有技术相比,本发明的有益效果是:
本发明通过全连续薄板坯轧制,结合全流程负荷分配,采用低碳、低锰、微钛成分设计,利用铸坯薄规格、高拉速浇铸、奥氏体完全再结晶、TiC抑制奥氏体晶粒长大等控制机理,获得薄规格高精度440MPa级高扩孔酸洗汽车钢,产品厚度为0.8~1.6mm,厚度波动≤±15μm,抗拉强度≥440MPa,屈服强度≥305MPa,也使得产品伸长率≥35%,扩孔率≥125%。本发明实现了440MPa级高扩孔酸洗汽车钢的“以酸代冷”,缩减现有薄规格高精度产品的制造流程。
附图说明
图1为采用本发明方法生产的一种薄规格高精度440MPa级高扩孔酸洗汽车钢及生产方法的组织形貌。
具体实施方式
为了更好地理解本发明,下面结合实施例进一步阐明本发明的内容,但本发明不仅仅局限于下面的实施例。本部分列举10组实施例说明本发明的实施情况。
实施例1~10
实施例1~10所提供的薄规格高精度440MPa级高扩孔酸洗汽车钢的化学成分如表1所示。
表1各实施例的化学成分(wt%)
C | Si | Mn | P | S | Ti | N | |
实施例1 | 0.057 | 0.05 | 0.79 | 0.0079 | 0.0017 | 0.025 | 0.0033 |
实施例2 | 0.04 | 0.121 | 0.61 | 0.0117 | 0.0025 | 0.035 | 0.0026 |
实施例3 | 0.055 | 0.082 | 0.50 | 0.0089 | 0.0016 | 0.03 | 0.0024 |
实施例4 | 0.042 | 0.125 | 0.54 | 0.0127 | 0.0033 | 0.04 | 0.0029 |
实施例5 | 0.044 | 0.098 | 0.71 | 0.0103 | 0.0022 | 0.05 | 0.0042 |
实施例6 | 0.055 | 0.11 | 0.66 | 0.009 | 0.0016 | 0.036 | 0.0036 |
实施例7 | 0.065 | 0.132 | 0.90 | 0.0091 | 0.005 | 0.042 | 0.002 |
实施例8 | 0.045 | 0.108 | 0.57 | 0.0075 | 0.0023 | 0.038 | 0.004 |
实施例9 | 0.048 | 0.159 | 0.69 | 0.0108 | 0.0027 | 0.031 | 0.0023 |
实施例10 | 0.064 | 0.175 | 0.85 | 0.0116 | 0.0023 | 0.03 | 0.005 |
实施例1~10所述薄规格高精度440MPa级高扩孔酸洗汽车钢的生产方法,主要包括铸坯浇铸、粗轧、感应加热、精轧、层流冷却、卷取、酸洗等步骤,具体步骤如下:
(1)冶炼及铸坯浇铸:按表1中按汽车钢的化学成分以及质量百分含量采用转炉或电炉冶炼并精炼后铸坯浇铸,铸坯拉速为5.5~7m/min,铸坯厚度为90~130mm;
(2)粗轧:将铸坯全连续粗轧至中间坯,中间坯厚度为9~20mm,粗轧单道次压下率50~65%;
(3)感应加热:采用感应加热将中间坯温度升至1160~1220℃;
(4)精轧:采用F1-F5精轧机组,将中间坯以全连续方式轧制至所需产品厚度,产品厚度为0.8~1.6mm,轧制道次为5道次,F1~F2压下率为40~60%,F3压下率为25~40%,其余道次(即F4~F5)压下率为10%~35%,F5轧制速度为6~14m/s,终轧温度为840~880℃;
(5)层流冷却:冷却速度为30~70℃/s;
(6)卷取:卷取温度控制为550~590℃;
(7)酸洗:采用常规酸洗工艺进行酸洗,得到薄规格高精度440MPa级高扩孔酸洗汽车钢带。
各实施例的工艺参数、主要性能分别如表1~表3所示。
表2各实施例加热工艺参数
表2(续)各实施例加热工艺参数
表3实施例1-10的典型力学性能和扩孔率、厚度指标
由图1可知,本发明生产的薄规格高精度440MPa级高扩孔酸洗汽车钢产品组织为均匀、细小的铁素体组织,有利于提高强度和扩孔率。
如表3所示,本生产的薄规格高精度440MPa级高扩孔酸洗汽车钢的产品厚度为0.8~1.6mm,抗拉强度≥440MPa,屈服强度≥305MPa,也使得产品伸长率≥35%,扩孔率≥125%。如实施例2、实施例6、实施例8所示,采用优化的成份和轧制工艺,实现0.8~1.2mm极薄规格高表面400MPa级高扩孔酸洗汽车钢的生产,产品抗拉强度为455~480MPa,屈服强度为325~350MPa,产品伸长率≥37%,扩孔率≥135%。本发明中,屈服强度、抗拉强度、伸长率采用标准GB/T 228.1检测,扩孔率采用标准GB/T 24524检测。
以上所述仅是本发明的优选实施方式,应当指出,对于本领域的普通技术人员来说,在不脱离本发明创造构思的前提下,还可以做出若干改进和变换,这些都属于本发明的保护范围。
Claims (8)
1.一种薄规格高精度440MPa级高扩孔酸洗汽车钢,其特征在于:按质量百分比计为:C0.04%~0.065%,Si 0.05%~0.2%,Mn 0.5%~0.9%,Ti 0.02%~0.05%,P≤0.015%,S≤0.005%,N≤0.005%,其余为Fe以及不可避免的杂质。
2.根据权利要求1所述的一种薄规格高精度440MPa级高扩孔酸洗汽车钢,其特征在于:产品抗拉强度≥440MPa,屈服强度≥305MPa,产品伸长率≥35%,扩孔率≥125%,厚度波动≤±15μm。
3.根据权利要求1所述的一种薄规格高精度440MPa级高扩孔酸洗汽车钢,其特征在于:按质量百分比计为:C 0.04%~0.055%,Si 0.08%~0.13%,Mn 0.5%~0.7%,P≤0.012%,S≤0.003%,Ti 0.03~0.04%,N≤0.004%,其余为Fe以及不可避免的杂质;产品抗拉强度为455~480MPa,屈服强度为325~350MPa,产品伸长率≥37%,扩孔率≥135%。
4.根据权利要求1所述的一种薄规格高精度440MPa级高扩孔酸洗汽车钢,其特征在于:厚度为0.8~1.6mm,厚度波动≤±15μm。
5.权利要求1~4中任一项所述的薄规格高精度440MPa级高扩孔酸洗汽车钢的生产方法,主要包括铸坯浇铸、粗轧、感应加热、精轧、层流冷却、卷取、酸洗步骤,其特征在于:
(1)铸坯浇铸:铸坯拉速为5.5~7m/min,铸坯厚度为90~130mm;
(2)粗轧:将铸坯全连续粗轧至中间坯,中间坯厚度为9~20mm,粗轧单道次压下率50~65%;
(3)感应加热:采用感应加热将中间坯温度升至1160~1220℃;
(4)精轧:采用F1-F5精轧机组,将中间坯以全连续方式轧制至所需产品厚度,产品厚度为0.8~1.6mm,轧制道次为5道次,F1~F2压下率为40~60%,F3压下率为25~40%,F4~F5压下率为10%~35%,F5轧制速度为6~14m/s,终轧温度为840~880℃;
(5)层流冷却:冷却速度为30~70℃/s;
(6)卷取:卷取温度控制为550~590℃;
(7)酸洗:采用常规酸洗工艺进行酸洗,得到薄规格高精度440MPa级高扩孔酸洗汽车钢。
6.根据权利要求5所述的薄规格高精度440MPa级高扩孔酸洗汽车钢的生产方法,其特征在于:铸坯拉速为6~7m/min,铸坯厚度为90~110mm。
7.根据权利要求5所述的薄规格高精度440MPa级高扩孔酸洗汽车钢的生产方法,其特征在于:中间坯厚度为9~15mm,粗轧单道次压下率58~65%。
8.根据权利要求5所述的薄规格高精度440MPa级高扩孔酸洗汽车钢的生产方法,其特征在于:产品厚度为0.8~1.2mm,轧制道次为5道次,F1~F2压下率为50~60%,F3压下率为33~40%,F4~F5压下率为20~35%,F5轧制速度为10~14m/s,终轧温度为840~860℃。
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