JP4765388B2 - Manufacturing method for cold rolled steel sheet with excellent flatness after punching - Google Patents
Manufacturing method for cold rolled steel sheet with excellent flatness after punching Download PDFInfo
- Publication number
- JP4765388B2 JP4765388B2 JP2005130982A JP2005130982A JP4765388B2 JP 4765388 B2 JP4765388 B2 JP 4765388B2 JP 2005130982 A JP2005130982 A JP 2005130982A JP 2005130982 A JP2005130982 A JP 2005130982A JP 4765388 B2 JP4765388 B2 JP 4765388B2
- Authority
- JP
- Japan
- Prior art keywords
- less
- rolling
- steel plate
- cooling
- steel sheet
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
- 238000004080 punching Methods 0.000 title claims description 18
- 238000004519 manufacturing process Methods 0.000 title claims description 17
- 239000010960 cold rolled steel Substances 0.000 title description 6
- 229910000831 Steel Inorganic materials 0.000 claims description 58
- 239000010959 steel Substances 0.000 claims description 58
- 238000001816 cooling Methods 0.000 claims description 34
- 238000005097 cold rolling Methods 0.000 claims description 27
- 238000005096 rolling process Methods 0.000 claims description 20
- 238000000137 annealing Methods 0.000 claims description 14
- 230000009466 transformation Effects 0.000 claims description 13
- 229910052748 manganese Inorganic materials 0.000 claims description 4
- 238000005554 pickling Methods 0.000 claims description 3
- 229910052799 carbon Inorganic materials 0.000 claims description 2
- 229910052757 nitrogen Inorganic materials 0.000 claims description 2
- 229910052698 phosphorus Inorganic materials 0.000 claims description 2
- 239000000463 material Substances 0.000 description 20
- 238000010438 heat treatment Methods 0.000 description 16
- 229910000859 α-Fe Inorganic materials 0.000 description 13
- 238000000034 method Methods 0.000 description 11
- 238000005098 hot rolling Methods 0.000 description 9
- 230000005540 biological transmission Effects 0.000 description 8
- 239000011572 manganese Substances 0.000 description 8
- 230000035882 stress Effects 0.000 description 6
- 230000000694 effects Effects 0.000 description 5
- 238000004804 winding Methods 0.000 description 5
- 239000012535 impurity Substances 0.000 description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 4
- 230000015572 biosynthetic process Effects 0.000 description 3
- 229910001562 pearlite Inorganic materials 0.000 description 3
- 229910000677 High-carbon steel Inorganic materials 0.000 description 2
- 241000446313 Lamella Species 0.000 description 2
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 2
- 229910001563 bainite Inorganic materials 0.000 description 2
- 230000003749 cleanliness Effects 0.000 description 2
- 229910052802 copper Inorganic materials 0.000 description 2
- 230000006866 deterioration Effects 0.000 description 2
- 230000018109 developmental process Effects 0.000 description 2
- 238000000265 homogenisation Methods 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 238000001556 precipitation Methods 0.000 description 2
- 238000010791 quenching Methods 0.000 description 2
- 230000000171 quenching effect Effects 0.000 description 2
- 239000006104 solid solution Substances 0.000 description 2
- 238000005728 strengthening Methods 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 229910052720 vanadium Inorganic materials 0.000 description 2
- 230000032683 aging Effects 0.000 description 1
- 229910001566 austenite Inorganic materials 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 238000009749 continuous casting Methods 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000002431 foraging effect Effects 0.000 description 1
- 229910052745 lead Inorganic materials 0.000 description 1
- 150000001247 metal acetylides Chemical class 0.000 description 1
- 238000011328 necessary treatment Methods 0.000 description 1
- 230000008520 organization Effects 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 238000007665 sagging Methods 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 238000005204 segregation Methods 0.000 description 1
- 238000010583 slow cooling Methods 0.000 description 1
- 238000009628 steelmaking Methods 0.000 description 1
- 238000004781 supercooling Methods 0.000 description 1
- 238000005496 tempering Methods 0.000 description 1
- 229910052718 tin Inorganic materials 0.000 description 1
- 238000011282 treatment Methods 0.000 description 1
Images
Landscapes
- Metal Rolling (AREA)
- Heat Treatment Of Sheet Steel (AREA)
Description
本発明は、自動車のトランスミッション部品としてのギアやプレート等の素材として好適な薄鋼板の製造方法に関するものであり、特に冷間圧延ままで打抜き後の寸法精度に優れ、しかも、打抜き部品の硬度確保のための熱処理工程が不要である打抜き後の平坦度に優れる薄鋼板の製造方法に関するものである。 The present invention relates to a manufacturing method of a preferred thin steel plate as a material for gears and plates such as transmission parts of automobiles, excellent dimensional accuracy after punching, especially while cold rolling, moreover, the hardness of the punched parts a heat treatment step for secured to a method for manufacturing a thin steel plate having excellent flatness after punching is not necessary.
自動車のトランスミッション部品として使用されるギヤやプレート等は、部品メーカーにおいて鋼板を所定の形状に打抜いた後、所望の硬度に調整するために打抜き後の部品に焼入れや時効析出等の硬化を目的とした熱処理を施すことによって製造される。 Gears and plates used as transmission parts for automobiles are used for hardening parts such as quenching and aging precipitation in order to adjust to the desired hardness after punching a steel sheet into a predetermined shape at a parts manufacturer. It is manufactured by applying the heat treatment.
しかし、近年、製造コストの削減を目的として、上記熱処理の代わりに、冷間圧延による硬度確保が可能な鋼板の開発が要求されている。ところが、このような冷間圧延による硬度確保では、打抜き後の部品に大きな反りが発生する場合があった。そのため、打抜き後の部品にプレステンパーと呼ばれる熱処理が必要となり、さらにこのプレステンパーを行っても、部品の形状矯正が困難な場合があった。 However, in recent years, for the purpose of reducing manufacturing costs, development of a steel sheet capable of securing hardness by cold rolling is required instead of the above heat treatment. However, when the hardness is ensured by such cold rolling, there is a case where a large warp occurs in a part after punching. Therefore, a heat treatment called press temper is required for the stamped part, and even if this press temper is performed, it may be difficult to correct the shape of the part.
このような現状から、冷間圧延ままで打抜き後の部品の平坦度に優れる鋼板の開発が強く望まれていた。 From such a current situation, there has been a strong demand for the development of a steel sheet that is excellent in the flatness of parts after being punched in the cold rolling state.
上記に対して、自動車のトランスミッション部品としてのギヤやプレート等の、打抜き後の硬度を確保するための熱処理を省略する従来技術として、特許文献1には、熱延板組織を硬質なベイニティックフェライトまたはベイナイトを主相とする精密打抜用高強度鋼板の製造方法が開示されている。 In contrast to the above, as a prior art that omits heat treatment for securing the hardness after punching, such as gears and plates as transmission parts of automobiles, Patent Document 1 describes that a hot-rolled sheet structure has a hard bainitic structure. A method for producing a high-strength steel sheet for precision punching having ferrite or bainite as a main phase is disclosed.
また、部品の寸法精度を確保しながら強度を向上させる技術に関しては、特許文献2に、熱歪が大きくなる焼入れ処理の代わりにＣｕやＶを添加して高強度化する高炭素鋼板およびその製造方法が開示されている。 In addition, regarding the technology for improving the strength while ensuring the dimensional accuracy of the parts, Patent Document 2 discloses a high-carbon steel sheet and its manufacture that add Cu and V to increase the strength instead of the quenching process that increases thermal strain. A method is disclosed.
さらに、特許文献3には、硬度と鋼板幅方向の板面硬度差の最大値を規定することにより、熱処理も省略可能とする、平坦度に優れる高炭素鋼板およびその製造方法が開示されている。
しかしながら、特許文献1は、次のような問題点を有している。まず、特許文献1は、冷間圧延後の精密打抜き性、即ち、ダレやせん断面比率等の打抜き面の形態制御に関するものであり、打抜き部品の平坦度に関しては何ら言及していない。さらに、ベイナイト等の低温変態相により強度を確保しているために、熱延時の巻取温度にバラツキが生じた場合、コイル長手方向、あるいは、広幅材ではコイル幅方向の材質変動が大きくなって、冷間圧延後の打抜き部品の寸法精度にバラツキが生じる。 However, Patent Document 1 has the following problems. First, Patent Document 1 relates to precision punchability after cold rolling, that is, control of the shape of the punched surface such as sagging and shear surface ratio, and does not mention anything about the flatness of the punched part. Furthermore, since the strength is secured by a low-temperature transformation phase such as bainite, if the coiling temperature varies during hot rolling, material fluctuations in the coil longitudinal direction or in the coil width direction increase in the wide width material. The dimensional accuracy of the punched parts after cold rolling varies.
特許文献2は、ＣｕやＶを時効析出させるための焼戻し処理温度での熱処理が必要であり、打抜部品の硬度確保のための熱処理を省略することができないという問題点を有している。 Patent Document 2 has a problem that heat treatment at a tempering treatment temperature for aging precipitation of Cu and V is necessary, and heat treatment for ensuring the hardness of the punched part cannot be omitted.
特許文献3は、熱間圧延する際の幅方向温度制御により、平坦度に優れた鋼板を得ようとするものであるが、コイル長手方向の材質制御が不十分で、バラツキを生じるという問題点を有している。 Patent Document 3 is intended to obtain a steel sheet with excellent flatness by temperature control in the width direction during hot rolling, but the problem is that the material control in the coil longitudinal direction is insufficient and variation occurs. have.
以上のように、薄鋼板の打抜き後の部品の平坦度に優れ、しかも、打抜き部品の硬度確保のための熱処理工程が不要な鋼板およびその製造方法は、未だ提案されていないのが現状である。 As described above, a steel sheet that is excellent in the flatness of a part after punching a thin steel sheet and that does not require a heat treatment step for securing the hardness of the punched part and a manufacturing method thereof have not been proposed yet. .
従って、本発明は、上記の事情に鑑み、自動車のトランスミッション部品としてのギヤやプレート等の素材として、打抜き部品の平坦度に優れ、しかも、打抜き部品の硬度確保のための熱処理工程が不要な薄鋼板の製造方法を提供することを目的とする。 Therefore, in view of the above circumstances, the present invention is excellent in the flatness of a punched part as a material such as a gear or a plate as a transmission part of an automobile, and further requires a heat treatment process for ensuring the hardness of the punched part. and to provide a method for manufacturing a steel plate.
本発明者らは、上記目的を達成するために、鋭意研究を重ねた。その結果、次のような知見を得た。 The inventors of the present invention have made extensive studies in order to achieve the above object. As a result, the following knowledge was obtained.
打抜き後の平坦度の劣化は、鋼板材質の不均一性による内部残留応力の発生に起因する。即ち、熱延板のコイル長手方向及び幅方向において大きな硬度差が生じる場合、冷間圧延後にも硬度差を生じるため、長手方向及び幅方向の位置による残留応力の差異が生じ、この結果、打抜き部品の平坦度が劣化する。そこで、打抜き部品の平坦度の劣化を防止するためには、以下の点が重要である。
（1）冷間圧延ままでのコイルの長手方向及び幅方向の材質を均一にする、とくに硬度差を小さくする。
（2）冷間圧延の母材となる熱延鋼板の長手方向及び幅方向の材質を均一にする、とくに、熱延鋼板の長手方向及び幅方向の硬度差を小さくする。これを適正な冷圧率で圧延し、均一な歪を付与した鋼板にすることにより、優れた打抜き後の平坦度が得られる。
（3）好ましくは冷間圧延前に焼鈍を行い、熱延板の残留応力低減および更なる材質均一化をはかる。
以上により極めて優れた打抜き後の平坦度が得られることになる。
The deterioration of flatness after punching is caused by the generation of internal residual stress due to the non-uniformity of the steel plate material. That is, when a large hardness difference occurs in the longitudinal direction and the width direction of the coil of the hot-rolled sheet, a difference in hardness occurs even after cold rolling, resulting in a difference in residual stress depending on the position in the longitudinal direction and the width direction. The flatness of parts deteriorates. Therefore, in order to prevent the flatness of the punched part from being deteriorated, the following points are important.
(1) Make the material in the longitudinal and width directions of the coil as cold-rolled uniform, especially reduce the hardness difference.
(2) To make the material in the longitudinal direction and the width direction of the hot-rolled steel sheet that is the base material for cold rolling uniform, in particular, to reduce the hardness difference between the longitudinal direction and the width direction of the hot-rolled steel sheet. An excellent flatness after punching can be obtained by rolling the steel sheet at an appropriate cold pressure ratio to give a uniform strain.
(3) Preferably, annealing is performed before cold rolling to reduce the residual stress and further homogenize the material of the hot-rolled sheet.
Thus, extremely excellent flatness after punching can be obtained.
本発明は、上記の知見に基づき完成されたものであり、本発明の要旨とするところは以下の通りである。
［1］質量％で、C：０.０５〜０.６％、Si:２.０％以下、Mn：０.２〜２.０％、P：０.０３％以下、S：０.０３％以下、Sol.Al：０.１％以下、N：０.０１％以下を含有し、残部はFe及び不可避不純物からなる組成を有する鋼を仕上温度 (Ar3変態点−20℃)以上で熱間圧延した後、冷却速度120℃/秒超、冷却停止温度650℃以下、鋼板幅方向センター部と鋼板エッジ部との冷却停止温度差が30℃以下となるように冷却を行い、次いで、巻取温度600℃以下で巻取り、酸洗後、圧下率40%以上で冷間圧延するか、もしくは、焼鈍温度600℃以上Ac1変態点以下で焼鈍後に圧下率40%以上で冷間圧延することにより鋼板板面硬度Ｈｖが170〜300であり、かつ、鋼板長手方向及び幅方向の各位置における板面硬度差の最大値ΔＨｖが20以下とすることを特徴とする打抜き後の平坦度に優れる冷間圧延ままの薄鋼板の製造方法。
The present invention has been completed based on the above findings, and the gist of the present invention is as follows.
[ 1 ] By mass%, C: 0.05-0.6%, Si: 2.0% or less, Mn: 0.2-2.0%, P: 0.03% or less, S: 0.03 % Or less, Sol.Al: 0.1% or less, N: 0.01% or less, with the balance being a steel composed of Fe and inevitable impurities at a finishing temperature (Ar 3 transformation point -20 ° C.) or higher. After hot rolling, cooling is performed so that the cooling rate exceeds 120 ° C./second, the cooling stop temperature is 650 ° C. or less, and the cooling stop temperature difference between the steel plate width direction center portion and the steel plate edge portion is 30 ° C. or less. Winding at a coiling temperature of 600 ° C or lower, pickling, and cold rolling at a reduction rate of 40% or higher, or cold rolling at an annealing temperature of 600 ° C or higher and an Ac 1 transformation point and after annealing at a rolling reduction of 40% or higher The steel plate surface hardness Hv is 170 to 300, and the flatness after punching is characterized in that the maximum value ΔHv of the plate surface hardness difference at each position in the longitudinal direction and the width direction of the steel plate is 20 or less. A method for producing cold rolled steel sheets that are excellent in temperature.
なお、本明細書において、鋼の成分を示す%は、すべて質量%である。 In the present specification, “%” indicating the component of steel is “% by mass”.
本発明によれば、自動車トランスミッション部品としてのギヤやプレート等の素材に好適な、打抜き寸法精度、とくに平坦度に優れ、しかも、打抜き部品の硬度確保のための熱処理工程が不要である鋼板が得られる。これらは、ギヤやプレート等の素材として使用すえる際のさまざまな特性を充分に有しているため、工業的に有用な効果がもたらされる。 According to the present invention, a steel plate suitable for materials such as gears and plates as automobile transmission parts, excellent in punching dimensional accuracy, particularly flatness, and not requiring a heat treatment process for securing the hardness of the punched parts is obtained. It is done. Since these have sufficient characteristics when used as materials such as gears and plates, industrially useful effects are brought about.
以下、本発明を詳細に説明する。 Hereinafter, the present invention will be described in detail.
（1）成分組成
まず、本発明における鋼の化学成分の限定理由について説明する。
(1) Component composition First, the reasons for limiting the chemical components of steel in the present invention will be described.
Ｃ：0．05〜0．6％
Ｃは、自動車のトランスミッション部品としてのギアやプレート等に必要な強度を付与する。また、C量が低すぎるとAr3点越えでの熱延仕上圧延が困難となり組織を均一化することができない。よって、C量は少なくとも0．05％は必要である。しかし、0．6％を超えて添加すると、急速冷却による硬質化のために巻き取りが困難となる。従って、この発明においては、Ｃ含有量を0．05％以上0．6％以下の範囲に限定した。
C: 0.05-0.6%
C gives necessary strength to gears, plates, and the like as transmission parts of automobiles. If the amount of C is too low, hot rolling finish rolling beyond the Ar3 point becomes difficult, and the structure cannot be made uniform. Therefore, the amount of C needs to be at least 0.05%. However, if added over 0.6%, winding becomes difficult due to hardening by rapid cooling. Therefore, in the present invention, the C content is limited to the range of 0.05% to 0.6%.
Ｓｉ：2.0％以下
Ｓｉは、焼入れ性を向上させるとともに固溶強化により素材強度を上昇させる元素であるため、0.005％以上含有することが好ましい。しかし、2.0％を超えて含有すると、初析フェライトが生成し易くなり、炭化物を実質的に含まないフェライト粒が多くなって、材質の均一化を阻害する。さらに炭化物を黒鉛化し、焼入れ性を阻害する傾向がある。従って、Ｓｉ含有量は2.0％以下とする。
Si: 2.0% or less Since Si is an element that improves the hardenability and increases the strength of the material by solid solution strengthening, it is preferably contained in an amount of 0.005% or more. However, if the content exceeds 2.0%, pro-eutectoid ferrite is likely to be generated, and ferrite grains that do not substantially contain carbides increase, which hinders homogenization of the material. Further, the carbide tends to be graphitized and the hardenability is hindered. Therefore, the Si content is 2.0% or less.
Ｍｎ：0.2〜2.0％
Mnは、Ｓｉと同様に焼入れ性を向上させるとともに固溶強化により素材強度を上昇させる元素である。また、ＳをＭｎＳとして固定し、スラブの熱間割れを防止する重要な元素である。しかし、Ｍｎ含有量が0.2％未満では、これらの効果が小さくなるとともに、初析フェライトの生成を助長し、フェライト粒を粗大化させ、材質の均一化を阻害する。また、焼入性を大幅に低下させる。一方、2.0％を超える場合は、引張強度は得られるが、偏析帯であるマンガンバンドの生成が顕著となり、延性が劣化する．従って、Ｍｎ含有量は0.2％以上2.0％以下とする。好ましくは、マンガンバンド生成による延性劣化の観点から1.0％以下である。
Mn: 0.2-2.0%
Mn is an element that improves the hardenability and raises the strength of the material by solid solution strengthening, like Si. Moreover, it is an important element which fixes S as MnS and prevents the hot crack of a slab. However, if the Mn content is less than 0.2%, these effects are reduced, and the formation of pro-eutectoid ferrite is promoted, the ferrite grains are coarsened, and the homogenization of the material is inhibited. In addition, the hardenability is greatly reduced. On the other hand, if it exceeds 2.0%, the tensile strength can be obtained, but the formation of a manganese band, which is a segregation band, becomes remarkable and the ductility deteriorates. Therefore, the Mn content is 0.2% or more and 2.0% or less. Preferably, it is 1.0% or less from the viewpoint of ductile deterioration due to manganese band formation.
Ｐ：0.03％以下
Ｐは、粒界に偏析し、靭性を低下させるため、低減しなければならない元素である。しかし、Ｐの含有量が0.03％までは許容できるため、Ｐ含有量は0.03％以下とする。
P: 0.03% or less P is an element that must be reduced in order to segregate at grain boundaries and reduce toughness. However, since the P content is acceptable up to 0.03%, the P content is set to 0.03% or less.
Ｓ：0.03％以下
Ｓは、ＭｎとＭｎＳを形成し伸びフランジ性を劣化させるため、低減しなければならない元素である。しかし、Ｓの含有量が0.03％までは許容できるため、Ｓ含有量は0.03％以下とする。
S: 0.03% or less S is an element that must be reduced in order to form Mn and MnS and degrade stretch flangeability. However, since the S content is acceptable up to 0.03%, the S content is set to 0.03% or less.
Sol.Al：0.1％以下
Alは、脱酸剤として用い、鋼の清浄度を向上させるため、製鋼段階で添加し、鋼中には通常Sol.Alで概ね0.005％以上含有される。一方、Sol.Al含有量が0.1％を超えて添加しても、清浄度を向上させるという効果が飽和しコスト増となる。また、過剰に添加するとAlNが多量に析出し焼入れ性を低下させる．従って、鋼中のSol.Al含有量は0.1％以下とする。好ましくは0.08％以下である。
Sol.Al: 0.1% or less
Al is used as a deoxidizer and is added at the steel making stage to improve the cleanliness of the steel. Usually, the steel contains approximately 0.005% or more of Sol.Al. On the other hand, even if the content of Sol.Al exceeds 0.1%, the effect of improving the cleanliness is saturated and the cost increases. If added in excess, a large amount of AlN precipitates, reducing the hardenability. Therefore, the content of Sol.Al in the steel is 0.1% or less. Preferably it is 0.08% or less.
Ｎ：0.01％以下
Ｎは、過剰に添加すると延性の低下をもたらすため、添加する場合、0.01％以下とする。
なお、上記以外の残部はＦｅおよび不可避的不純物からなる。
N: 0.01% or less N is added in excess, so that ductility is lowered.
The balance other than the above consists of Fe and inevitable impurities.
また、製造過程でSn、Pb等の各種元素が不純物として混入する場合があるが、このような不純物も本発明の効果にとくに影響を及ぼすものではない。 In addition, various elements such as Sn and Pb may be mixed as impurities during the manufacturing process, but such impurities do not particularly affect the effects of the present invention.
（2）鋼板硬度
本発明の薄鋼板の硬度の限定理由について説明する。
ギアやプレート等の自動車のトランスミッション部品に適用する場合には鋼板硬度はとくに重要であり、冷間圧延ままの鋼板の板面硬度Ｈｖが170未満の場合には十分な耐磨耗性が得られず、一方、Ｈｖが300を超えるような場合には、逆に相手材の損耗を増大させる。そのため、鋼板板面硬度Ｈｖを、170以上300以下とする。より好ましくは、200以上270以下である。
(2) Steel plate hardness The reason for limiting the hardness of the thin steel plate of the present invention will be described.
Steel plate hardness is particularly important when applied to automobile transmission parts such as gears and plates. When the surface hardness Hv of a cold-rolled steel plate is less than 170, sufficient wear resistance is obtained. On the other hand, when Hv exceeds 300, conversely, the wear of the counterpart material is increased. Therefore, the steel plate surface hardness Hv is set to 170 or more and 300 or less. More preferably, it is 200 or more and 270 or less.
鋼板長手方向及び幅方向各位置における板面硬度差の最大値ΔＨｖが20を超えると鋼板の残留応力に不均一が生じ、打抜き後の平坦度が低下するため、ΔＨｖは20以下とする。また、優れた平坦度を得るためには、ΔＨｖを15以下とするのが好ましい。
熱延鋼板の長手方向及び幅方向位置による板面硬度差が大きい場合には、適正な冷圧率で、冷間圧延を実施しても、硬度差が解消できず冷間圧延後の硬度差も大きくなるため、残留応力に差異が生じ、打抜き部品の優れた平坦度が得られない。従って、熱延鋼板長手方向及び幅方向各位置における板面硬度差の最大値ΔＨｖを20以下とすることが望ましい。また、極めて優れた寸法精度を得るためには、最大硬度差ΔＨｖは15以下が好ましい。
なお、本発明でいう硬度Ｈｖとは、ビッカース硬さである。
If the maximum value ΔHv of the sheet surface hardness difference at each position in the longitudinal direction and the width direction of the steel sheet exceeds 20, the residual stress of the steel sheet becomes non-uniform and the flatness after punching decreases, so ΔHv is set to 20 or less. In order to obtain excellent flatness, ΔHv is preferably 15 or less.
If the sheet surface hardness difference due to the longitudinal and width direction positions of the hot-rolled steel sheet is large, even if cold rolling is carried out at an appropriate cold pressure ratio, the hardness difference cannot be resolved and the hardness difference after cold rolling Therefore, a difference occurs in the residual stress, and an excellent flatness of the punched part cannot be obtained. Therefore, it is desirable that the maximum value ΔHv of the sheet surface hardness difference at each position in the longitudinal direction and the width direction of the hot-rolled steel sheet is 20 or less. In order to obtain extremely excellent dimensional accuracy, the maximum hardness difference ΔHv is preferably 15 or less.
The hardness Hv in the present invention is Vickers hardness.
（3）製造条件
本発明の薄鋼板の製造条件の限定理由について説明する。
本発明鋼板は、本発明に規定する成分組成の鋼スラブを（Ａ）熱間圧延−酸洗−冷間圧延−調質圧延、（Ｂ）熱間圧延−酸洗−球状化焼鈍−冷間圧延−調質圧延のいずれかの工程を経て製造される。
(3) Manufacturing conditions The reasons for limiting the manufacturing conditions of the thin steel sheet of the present invention will be described.
The steel sheet of the present invention is obtained by (A) hot rolling-pickling-cold rolling-temper rolling, (B) hot rolling-pickling-spheroidizing annealing-cold rolling. It is manufactured through any process of rolling-temper rolling.
本発明鋼板を製造する場合、熱延プロセスはスラブ加熱後圧延する方法、連続鋳造後短時間の加熱処理を施してあるいは該加熱工程を省略して直ちに圧延する方法のいずれでもよいが、優れた表面品質を付与するためには、一次スケールのみならず熱間圧延時に生成する二次スケールについても十分に除去するのが好ましい。また、熱間圧延においては、粗圧延と仕上圧延との間で、バーヒーターにより粗バー加熱を行ってもよい。更に、熱延鋼板の幅方向の組織の均一化を図るため、エッジヒーターにより粗バーエッジ部を加熱し、エッジ部の過冷却を抑制することが望ましい。 When producing the steel sheet of the present invention, the hot rolling process may be either a method of rolling after slab heating, a method of performing a heat treatment for a short time after continuous casting or a method of rolling immediately after omitting the heating step. In order to impart surface quality, it is preferable to sufficiently remove not only the primary scale but also the secondary scale generated during hot rolling. In hot rolling, coarse bar heating may be performed by a bar heater between rough rolling and finish rolling. Furthermore, in order to make the structure in the width direction of the hot-rolled steel sheet uniform, it is desirable to heat the rough bar edge portion with an edge heater to suppress overcooling of the edge portion.
仕上温度： (Ar3変態点-20℃)以上
熱間圧延の仕上温度が(Ar3変態点-20℃)未満では、一部でフェライト変態が進行するため炭化物を含まないフェライト粒が増加し、組織の均一化を図ることができない。そこで、(Ar3変態点-20℃)以上の仕上温度で仕上圧延する。仕上温度が高すぎると組織の均一化が困難となるため950℃以下とすることが望ましい。
Finishing temperature: The finishing temperature of (Ar 3 transformation point -20 ° C.) or higher hot rolling is less than (Ar 3 transformation point -20 ° C.), ferrite grains not containing carbide because ferrite transformation proceeds in some increases The organization cannot be made uniform. Therefore, finish rolling is performed at a finishing temperature of (Ar 3 transformation point −20 ° C.) or higher. If the finishing temperature is too high, it becomes difficult to homogenize the structure.
圧延後の冷却条件： 冷却速度＞120℃/秒
本発明では、変態後のフェライト粒の体積率を低減し、コイル長手方向及び幅方向の組織の均一化を図るため、圧延後に急冷（冷却）を行う。冷却方法が徐冷であると、オーステナイトの過冷度が小さく初析フェライトが生成する。冷却速度が120℃/秒以下の場合、初析フェライトの生成が顕著となり、組織の均一化が困難になる。従って、圧延後の冷却の冷却速度は120℃/秒超とする。
Cooling conditions after rolling: Cooling rate> 120 ° C./second In the present invention, in order to reduce the volume fraction of ferrite grains after transformation and to make the structure in the coil longitudinal direction and width direction uniform, rapid cooling after cooling (cooling) I do. When the cooling method is slow cooling, the degree of supercooling of austenite is small and proeutectoid ferrite is generated. When the cooling rate is 120 ° C./second or less, pro-eutectoid ferrite is remarkably generated and it is difficult to make the structure uniform. Therefore, the cooling rate of the cooling after rolling is over 120 ° C./second.
冷却停止温度： 650℃以下
圧延後の冷却の冷却停止温度が高い場合、巻取りまでの冷却中にフェライトが生成するとともに、パーライトのラメラ間隔が粗大化する。そのため、焼鈍後に微細炭化物が得られなくなり、組織の均一化が困難になる。冷却停止温度が650℃より高い場合、炭化物を含まないフェライト粒が10％超となり、最終冷間圧延後の平坦度が劣化する。従って、圧延後の冷却の冷却停止温度を650℃以下とする。一方、450℃未満になると、等軸フェライト粒が得られず、組織の均一化が困難なことがあるので、冷却停止温度の下限は450℃以上とすることが望ましい。
Cooling stop temperature: 650 ° C. or less When the cooling stop temperature after rolling is high, ferrite is generated during cooling up to winding, and the lamella spacing of pearlite becomes coarse. Therefore, fine carbide cannot be obtained after annealing, and it becomes difficult to make the structure uniform. When the cooling stop temperature is higher than 650 ° C., the ferrite grains not containing carbide exceed 10%, and the flatness after the final cold rolling deteriorates. Therefore, the cooling stop temperature for cooling after rolling is set to 650 ° C. or lower. On the other hand, if the temperature is lower than 450 ° C., equiaxed ferrite grains cannot be obtained, and it may be difficult to make the structure uniform. Therefore, the lower limit of the cooling stop temperature is preferably 450 ° C. or higher.
鋼板幅方向センター部と鋼板エッジ部との冷却停止温度差が30℃以下
ランナウト冷却中は、鋼板エッジ部の水乗りを防止し、エッジ部の過冷却を抑制することが好ましい。そして、幅方向の材質均一性を確保するために、鋼板幅方向センター部と鋼板エッジ部との冷却停止温度差が30℃以下とする。なお、エッジ部の水乗り防止は、エッジ部の水冷ノズルの調整あるいは遮蔽板により水量を調整する。
During the runout cooling where the cooling stop temperature difference between the steel plate width direction center portion and the steel plate edge portion is 30 ° C. or less, it is preferable to prevent the steel plate edge portion from getting on the water and suppress the overcooling of the edge portion. And in order to ensure the material uniformity of the width direction, the cooling stop temperature difference of a steel plate width direction center part and a steel plate edge part shall be 30 degrees C or less. In order to prevent water riding on the edge portion, the amount of water is adjusted by adjusting a water cooling nozzle at the edge portion or by a shielding plate.
巻取温度： 600℃以下
冷却後は鋼板を巻き取るが、巻取温度が高いほどパーライトのラメラ間隔が大きくなる。そのため、焼鈍後の炭化物が粗大化し、巻取温度が600℃を超えると最終冷間圧延後の平坦度が劣化する。従って、巻取温度を600℃以下とする。巻取温度が500℃未満の場合には、ランナウト上での冷却が大きく、熱延板の形状が劣化し幅方向で不均一な残留応力が発生し、打抜き後の寸法精度が劣化しやすいため、500℃以上とすることが望ましい。
Winding temperature: The steel sheet is wound after cooling below 600 ° C. The higher the winding temperature, the greater the pearlite lamella spacing. Therefore, the carbide after annealing becomes coarse, and when the coiling temperature exceeds 600 ° C., the flatness after the final cold rolling deteriorates. Accordingly, the coiling temperature is set to 600 ° C. or lower. When the coiling temperature is less than 500 ° C, the cooling on the runout is large, the shape of the hot-rolled sheet deteriorates, non-uniform residual stress occurs in the width direction, and the dimensional accuracy after punching tends to deteriorate. It is desirable that the temperature be 500 ° C.
焼鈍温度： 600℃以上Ac1変態点以下
熱延板を酸洗後、焼鈍を行うことにより冷間圧延後の打抜き部品の平坦度が更に向上する。炭化物を球状化するために焼鈍を行うが、焼鈍温度が600℃未満の場合、炭化物の球状化が不十分となり、組織が不均一になる。一方、焼鈍温度がAc1変態点を超える場合、一部がオーステナイト化し、冷却中に再度パーライトを生成するため、組織の均一化に問題が生じる。680℃を超えると軟質化しすぎるため冷間圧延率を高くせざるを得なくなり、逆に打抜き後の寸法精度は劣化する。また、この効果を得るには20時間以上の焼鈍が必要となる。従って、とくに優れた平坦度が求められる場合には、酸洗後に、600〜680℃の温度で20時間以上の焼鈍を行うことが望ましい。
Annealing temperature: 600 ° C. or more and Ac 1 transformation point or less The hot-rolled sheet is pickled and then annealed to further improve the flatness of the punched part after cold rolling. Annealing is performed to spheroidize the carbide, but when the annealing temperature is less than 600 ° C., the spheroidization of the carbide becomes insufficient and the structure becomes non-uniform. On the other hand, when the annealing temperature exceeds the Ac 1 transformation point, a part is austenitized, and pearlite is generated again during cooling, which causes a problem in homogenizing the structure. If it exceeds 680 ° C, it becomes so soft that the cold rolling rate has to be increased, and conversely the dimensional accuracy after punching deteriorates. Further, to obtain this effect, annealing for 20 hours or more is required. Therefore, when particularly excellent flatness is required, it is desirable to perform annealing at a temperature of 600 to 680 ° C. for 20 hours or more after pickling.
冷間圧延
熱延時の冷却速度、冷却停止温度を制御することにより、長手方向及び幅方向の組織均一性に優れた熱延鋼板の製造が達成できるが、これに40％以上の圧下率で均一な歪を加えることにより、平坦度に優れる冷間圧延ままの鋼板を得ることができる。冷間圧延時の圧延率が、70％を超えるような高い圧延率の場合、圧延負荷が高くなりすぎるため生産性を低下させる。このため、冷間圧延率は70％以下とすることが望ましい。このときの冷間圧延はタンデム圧延、リバース圧延のいずれでも良い。
By controlling the cooling rate and cooling stop temperature during cold rolling hot rolling, it is possible to achieve the production of hot rolled steel sheets with excellent longitudinal and width structural uniformity, but with a reduction rate of 40% or more. By applying an appropriate strain, a cold-rolled steel plate having excellent flatness can be obtained. When the rolling rate during cold rolling is such a high rolling rate that exceeds 70%, the rolling load becomes too high and the productivity is lowered. For this reason, it is desirable that the cold rolling rate be 70% or less. The cold rolling at this time may be either tandem rolling or reverse rolling.
表1に示す鋼板Ａから鋼板Ｅの化学成分組成を有する鋼を溶製し、次いで表2に示した製造条件に従って熱間圧延−冷間圧延あるいは熱間圧延−焼鈍−冷間圧延を行って板幅1000ｍｍ、板厚1．80ｍｍの冷延薄鋼板を製造した。 Steel having the chemical composition of steel plate E from steel plate A shown in Table 1 is melted, and then hot rolling-cold rolling or hot rolling-annealing-cold rolling is performed according to the manufacturing conditions shown in Table 2. A cold-rolled thin steel plate having a plate width of 1000 mm and a plate thickness of 1.80 mm was produced.
このようにして製造した冷延鋼板の長手方向3ヶ所の位置（Ｔ部、M部、B部）及び幅方向3ヶ所の位置（センター及び両エッジから15mm）で板面硬度Ｈｖを測定し、硬度差を求めた。また、このようにして得られた冷延鋼板をレベラーにて形状矯正を行った後、この薄鋼板から直径89ｍｍの円盤状試験片を打抜き（クリアランス：12％）、試験片の平坦度について評価した。
平坦度は、硬度測定と同じ位置よりサンプルを採取し、図1に示す最大反り高さ（幅方向最大高さ）を測定し、評価した。これらの結果を表3に示す。
The sheet surface hardness Hv was measured at three positions in the longitudinal direction (T part, M part, B part) and three positions in the width direction (15 mm from the center and both edges) of the cold-rolled steel sheet thus manufactured. The hardness difference was determined. In addition, after correcting the shape of the cold-rolled steel sheet thus obtained with a leveler, a disk-shaped specimen having a diameter of 89 mm is punched from this thin steel sheet (clearance: 12%), and the flatness of the specimen is evaluated. did.
The flatness was evaluated by measuring a maximum warp height (maximum height in the width direction) shown in FIG. These results are shown in Table 3.
表3から明らかなように、本発明例であるNo1〜7では、鋼板長手方向及び幅方向の硬度差ΔＨｖが20以下で、反り高さが小さく、優れた品質が得られることが明らかとなった。また、冷間圧延前に焼鈍を実施することにより、更に優れた品質が得られることが明らかとなった。
一方、比較例では、鋼板長手方向及び幅方向の硬度差ΔＨｖが20より大きく、そのため、反り高さが大きくなり、平坦度が劣っている。特に、製造条件を同一とした場合でも、Ｃが低いNo15では最終硬度のばらつきが多きくかつ反り高さが大きくなった。
As is apparent from Table 3, in No. 1 to No. 7 as examples of the present invention, it is clear that the hardness difference ΔHv in the longitudinal direction and the width direction of the steel sheet is 20 or less, the warp height is small, and excellent quality is obtained. It was. It has also been clarified that further excellent quality can be obtained by annealing before cold rolling.
On the other hand, in the comparative example, the hardness difference ΔHv between the steel plate longitudinal direction and the width direction is larger than 20, so that the warp height increases and the flatness is inferior. In particular, even when the manufacturing conditions were the same, in No15 where C was low, the final hardness varied greatly and the warp height increased.
本発明の薄鋼板は、打抜き寸法精度、とくに平坦度に優れており、打抜き部品の硬度確保のための熱処理工程が不要である。そのため、自動車トランスミッション部品としてのギヤやプレート等の素材を中心に、工業的に有用な材料である。 The thin steel sheet of the present invention is excellent in punching dimensional accuracy, particularly flatness, and does not require a heat treatment step for ensuring the hardness of the punched part. Therefore, it is an industrially useful material mainly for materials such as gears and plates as automobile transmission parts.
Claims (1)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2005130982A JP4765388B2 (en) | 2005-04-28 | 2005-04-28 | Manufacturing method for cold rolled steel sheet with excellent flatness after punching |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2005130982A JP4765388B2 (en) | 2005-04-28 | 2005-04-28 | Manufacturing method for cold rolled steel sheet with excellent flatness after punching |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP2006307281A JP2006307281A (en) | 2006-11-09 |
| JP4765388B2 true JP4765388B2 (en) | 2011-09-07 |
Family
ID=37474495
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2005130982A Active JP4765388B2 (en) | 2005-04-28 | 2005-04-28 | Manufacturing method for cold rolled steel sheet with excellent flatness after punching |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP4765388B2 (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP5633594B2 (en) | 2013-04-02 | 2014-12-03 | Ｊｆｅスチール株式会社 | Cold-rolled steel sheet excellent in punchability and heat-strain resistance and method for producing the same |
| WO2016152148A1 (en) * | 2015-03-25 | 2016-09-29 | Ｊｆｅスチール株式会社 | High-strength steel sheet and method for manufacturing same |
| CN114990436A (en) * | 2022-05-25 | 2022-09-02 | 鞍钢冷轧钢板（莆田）有限公司 | High-hardness cold-rolled sheet for microwave oven and production method thereof |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0441618A (en) * | 1990-06-07 | 1992-02-12 | Sumitomo Metal Ind Ltd | Production of cold rolled high carbon steel sheet |
| JP4151443B2 (en) * | 2003-03-24 | 2008-09-17 | Ｊｆｅスチール株式会社 | Thin steel plate with excellent flatness after punching and method for producing the same |
-
2005
- 2005-04-28 JP JP2005130982A patent/JP4765388B2/en active Active
Also Published As
| Publication number | Publication date |
|---|---|
| JP2006307281A (en) | 2006-11-09 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| JP5050433B2 (en) | Method for producing extremely soft high carbon hot-rolled steel sheet | |
| EP3653736B1 (en) | Hot-rolled steel strip and manufacturing method | |
| KR101084874B1 (en) | Hot-rolled high-carbon steel sheets and process for production of the same | |
| CN114686777A (en) | Flat steel product with good aging resistance and method for the production thereof | |
| WO2013180180A1 (en) | High strength cold-rolled steel plate and manufacturing method therefor | |
| KR102570145B1 (en) | High-carbon hot-rolled steel sheet and manufacturing method thereof | |
| JP4650006B2 (en) | High carbon hot-rolled steel sheet excellent in ductility and stretch flangeability and method for producing the same | |
| WO2015004902A1 (en) | High-carbon hot-rolled steel sheet and production method for same | |
| WO2015146174A1 (en) | High-carbon hot-rolled steel sheet and method for producing same | |
| JP2017179596A (en) | High carbon steel sheet and manufacturing method therefor | |
| JP2011080106A (en) | High strength cold-rolled steel sheet excellent in balance of extension and formability for extending flange | |
| JP5280795B2 (en) | Method for producing high-strength cold-rolled steel sheet with excellent mechanical property stability | |
| CN111655893B (en) | High carbon hot-rolled steel sheet and method for producing same | |
| JP4644075B2 (en) | High-strength steel sheet with excellent hole expansibility and manufacturing method thereof | |
| JP5462742B2 (en) | Method for producing high-strength steel sheet with excellent mechanical property stability | |
| JPH10251794A (en) | Hot rolled steel plate for structural purpose, excellent in press formability and surface characteristic, and its production | |
| JP2010047834A (en) | Cold-rolled steel sheet, process for production of same, and backlight chassis | |
| JP5860345B2 (en) | High-strength cold-rolled steel sheet with small variation in mechanical properties and method for producing the same | |
| JP4765388B2 (en) | Manufacturing method for cold rolled steel sheet with excellent flatness after punching | |
| KR20210009606A (en) | Austenitic stainless steel with imporoved strength and method for manufacturing the same | |
| KR102451005B1 (en) | High-strength steel sheet having excellent thermal stability and method for mnufacturing thereof | |
| JPH09324212A (en) | Production of hot rolled high carbon steel strip excellent in hardenability and cold workability | |
| KR20150075351A (en) | Rolled steel and method of manufacturing the same | |
| KR101353551B1 (en) | High carbon hot/cold rolled steel coil and manufactureing method thereof | |
| KR101242692B1 (en) | High carbon hot/cold rolled steel coil and manufactureing method thereof |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| RD01 | Notification of change of attorney |
Free format text: JAPANESE INTERMEDIATE CODE: A7421 Effective date: 20060921 |
|
| A621 | Written request for application examination |
Free format text: JAPANESE INTERMEDIATE CODE: A621 Effective date: 20080325 |
|
| A977 | Report on retrieval |
Free format text: JAPANESE INTERMEDIATE CODE: A971007 Effective date: 20100423 |
|
| A131 | Notification of reasons for refusal |
Free format text: JAPANESE INTERMEDIATE CODE: A131 Effective date: 20100511 |
|
| A02 | Decision of refusal |
Free format text: JAPANESE INTERMEDIATE CODE: A02 Effective date: 20110118 |
|
| A521 | Request for written amendment filed |
Free format text: JAPANESE INTERMEDIATE CODE: A523 Effective date: 20110330 |
|
| A911 | Transfer to examiner for re-examination before appeal (zenchi) |
Free format text: JAPANESE INTERMEDIATE CODE: A911 Effective date: 20110418 |
|
| TRDD | Decision of grant or rejection written | ||
| A01 | Written decision to grant a patent or to grant a registration (utility model) |
Free format text: JAPANESE INTERMEDIATE CODE: A01 Effective date: 20110517 |
|
| A61 | First payment of annual fees (during grant procedure) |
Free format text: JAPANESE INTERMEDIATE CODE: A61 Effective date: 20110530 |
|
| R150 | Certificate of patent or registration of utility model |
Free format text: JAPANESE INTERMEDIATE CODE: R150 Ref document number: 4765388 Country of ref document: JP Free format text: JAPANESE INTERMEDIATE CODE: R150 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20140624 Year of fee payment: 3 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |