JPH0784618B2 - Method for producing cold-rolled steel sheet for deep drawing excellent in secondary processing brittleness resistance - Google Patents
Method for producing cold-rolled steel sheet for deep drawing excellent in secondary processing brittleness resistanceInfo
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- JPH0784618B2 JPH0784618B2 JP1230873A JP23087389A JPH0784618B2 JP H0784618 B2 JPH0784618 B2 JP H0784618B2 JP 1230873 A JP1230873 A JP 1230873A JP 23087389 A JP23087389 A JP 23087389A JP H0784618 B2 JPH0784618 B2 JP H0784618B2
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- 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
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Description
【発明の詳細な説明】 （産業上の利用分野） 本発明は連続焼鈍による耐２次加工脆性に優れた深絞り
用冷延鋼板の製造方法に関するものである。TECHNICAL FIELD The present invention relates to a method for producing a cold-rolled steel sheet for deep drawing which is excellent in secondary work brittleness resistance due to continuous annealing.
（従来の技術） 近年、自動車部材や電気機器外板に使用される冷延鋼板
には、高いプレス成形性が要求されている。(Prior Art) In recent years, high press formability is required for cold-rolled steel sheets used for automobile members and outer panels of electric devices.
このような要求を満たす冷延鋼板の製造方法としては、
極低炭素鋼にTi、Nbなどの炭窒化物形成元素を単独又は
複合添加して鋼中のＣ、Ｎを固定することにより、深絞
り性に有利な（111）面方位集合組織を発達させる方法
が提案されている。As a method for manufacturing a cold rolled steel sheet that satisfies such requirements,
By fixing carbon and N in the steel by adding carbonitride forming elements such as Ti and Nb to ultra-low carbon steel alone or in combination, develop (111) plane orientation texture advantageous for deep drawability. A method has been proposed.
（発明が解決しようとする課題） しかし、一方では、Ti、Nbなどの炭窒化物形成元素によ
り鋼中のＣ、Ｎを充分固定した極低炭素鋼では、プレス
成形後の２次加工において脆性破断による割れが発生す
るという問題がある。これは、鋼中の固溶Ｃが固定さ
れ、フェライト粒界へのＣの偏析がなくなって粒界が脆
化するためである。(Problems to be Solved by the Invention) However, on the other hand, in an ultra-low carbon steel in which C and N in steel are sufficiently fixed by carbonitride forming elements such as Ti and Nb, brittleness occurs in secondary working after press forming. There is a problem that cracking occurs due to breakage. This is because the solid solution C in the steel is fixed, and the segregation of C in the ferrite grain boundaries disappears and the grain boundaries become brittle.
更に、Ｐ添加鋼では、粒界にＰが偏析し、粒界を脆化を
助長するという問題がある。Further, in the P-added steel, there is a problem that P segregates at the grain boundaries, which promotes embrittlement of the grain boundaries.
したがって、従来は、耐２次加工脆性の改善のために、
予め鋼中のＣ、Ｎが残存するようにTiやNbの添加量を制
御して溶製することが試みられていた。しかし、この方
法では、例え固溶Ｃ、Ｎが残存する成分鋼が溶製できた
としても、この固溶Ｃ、Ｎは本質的に鋼のｒ値や延性を
劣化させるものであるので、プレス成形性の大幅な低下
を来たさざるを得なかった。すなわち、本質的にプレス
成形性と耐２次加工脆性は両立し得ないものであった。
また、一方、このような微量Ｃ、Ｎを残存させること
は、製鋼技術上成り立つものでなかった。Therefore, conventionally, in order to improve the secondary processing brittleness resistance,
It has been attempted in advance to control the amount of addition of Ti and Nb so that C and N in the steel remain, and perform melting. However, in this method, even if the component steel in which the solid solution C and N remain can be produced, since the solid solution C and N essentially deteriorate the r value and ductility of the steel, Inevitably, the formability was significantly reduced. That is, the press formability and the secondary work embrittlement resistance were essentially incompatible.
On the other hand, leaving such a small amount of C and N was not established in steelmaking technology.
この点、従来より、以下のような提案がなされている
が、プレス成形性と耐２次加工脆性を共に優れたものと
することは困難である。In this respect, conventionally, the following proposals have been made, but it is difficult to provide both excellent press formability and secondary work brittleness resistance.
例えば、深絞り用鋼板の耐２次加工割れ性を改善する目
的で、Ti、Nbを添加して鋼中のＣを固定し、冷間圧延後
オープンコイル焼鈍時に浸炭を行い、鋼板表面に浸炭層
を形成する方法（特開昭63−38556号）が提案されてい
る。しかし、この方法の場合、長時間に及ぶバッチ焼鈍
の際に浸炭を実施するため、鋼板の表層部にのみ高濃度
の浸炭層（平均Ｃ量:0.02〜0.10％）が形成され、また
表層部と中心部でフェライト粒度に差が生じる等、板厚
方向に成分、組織が異なる鋼板となる問題があり、更
に、こうしたバッチ焼鈍タイプでは、当然乍ら生産性が
低いと共に、板長及び板幅方向の材質が不均一になり易
い不利を生じる。For example, in order to improve the resistance to secondary work cracking of deep drawing steel sheet, Ti and Nb are added to fix C in the steel, and carburizing is performed during open coil annealing after cold rolling to carburize the steel sheet surface. A method of forming a layer (Japanese Patent Laid-Open No. 63-38556) has been proposed. However, in the case of this method, since carburization is performed during batch annealing for a long time, a high-concentration carburized layer (average C amount: 0.02 to 0.10%) is formed only on the surface layer of the steel sheet, and There is a problem that the steel sheet has a different composition and structure in the plate thickness direction, such as a difference in the ferrite grain size between the center and the center.In addition, the batch annealing type naturally has low productivity and the plate length and plate width. There is a disadvantage that the material in the direction tends to be non-uniform.
また、同様に、Ti、Nbを添加して深絞り用鋼板を製造す
る方法として、冷間圧延後に再結晶焼鈍を行なった後、
更に浸炭処理を施す方法（特開平１−96330号）もある
が、主に多量の炭化物、窒化物の析出による強度の向上
を狙ったものであって、耐２次加工脆性に対する配慮が
なく、また焼鈍後にバッチにて長時間浸炭処理を行うた
め、浸炭量が過剰且つ不均一となり易く、しかも生産性
が低く、工程も煩雑になるという欠点がある。Further, similarly, as a method for producing a deep-drawing steel sheet by adding Ti, Nb, after performing recrystallization annealing after cold rolling,
There is also a method of carrying out a carburizing treatment (Japanese Patent Laid-Open No. 1-96330), but this is mainly aimed at improving the strength by precipitation of a large amount of carbides and nitrides, and there is no consideration for secondary work embrittlement resistance. In addition, since carburizing is performed for a long time in a batch after annealing, there is a drawback that the amount of carburizing tends to be excessive and non-uniform, the productivity is low, and the process is complicated.
本発明は、上記従来技術の技術の問題点を解決するため
になされたものであって、極低炭素鋼を用いて、プレス
成形性を損なうことなく、耐２次加工脆性に優れた深絞
り用冷延鋼板を生産性よく製造する方法を提供すること
を目的とするものである。The present invention has been made in order to solve the problems of the above-mentioned conventional techniques, and uses an ultra-low carbon steel, which does not impair the press formability and is excellent in deep drawing resistance to secondary working brittleness. An object of the present invention is to provide a method for producing a cold-rolled steel sheet for use with high productivity.
（課題を解決するための手段） かゝる目的を達成するため、本発明者らは、従来の極低
炭素鋼においてプレス成形性が劣化する原因について検
討した。(Means for Solving the Problem) In order to achieve such an object, the present inventors examined the cause of deterioration of press formability in conventional ultra low carbon steel.
その結果、固溶Ｃ、Ｎがプレス成形性を低下させる原因
は、圧延集合組織の形成段階及び再結晶集合組織の形成
段階で局所的なすべり系、転位の再配列に影響を及ぼ
し、深絞り性に好ましい（111）集合組織の発達を阻害
するためであることが判明した。As a result, the causes of solute C and N lowering the press formability affect the local slip system and rearrangement of dislocations in the rolling texture formation stage and the recrystallization texture formation stage, resulting in deep drawing. It was found that this is because it inhibits the development of (111) texture, which is favorable for sex.
そこで、本発明者らは、このような原因を解消し、且つ
耐２次加工脆性を優れたものとし得る方策について鋭意
研究を重ねた結果、極低炭素鋼において特定の成分調整
を行うと共に圧延条件を規定することによって、再結晶
集合組織が決定される焼鈍時の再結晶完了までは固溶
Ｃ、Ｎを零の状態にしておき、その後浸炭雰囲気ガス中
で連続焼鈍を行うことにより、最終製品段階で粒界に数
ppm程度のＣを存在させ、粒界を強化することにより、
脆化を防止する方法を見い出し、ここに本発明をなした
ものである。Therefore, the inventors of the present invention have conducted intensive studies on a method for eliminating such a cause and improving the secondary work embrittlement resistance, and as a result, adjusted specific components and rolled the ultra low carbon steel. By defining the conditions, the recrystallized texture is determined and the solid solution C and N are kept in the state of zero until the recrystallization is completed at the time of annealing, and then the continuous annealing is performed in the carburizing atmosphere gas to obtain the final Number at grain boundary at product stage
By adding C of about ppm and strengthening the grain boundary,
A method for preventing embrittlement has been found, and the present invention has been made here.
すなわち、本発明は、C:0.007％以下、Mn:0.05〜0.50
％、P:0.12％以下、S:0.015％以下、sol.Al:0.005〜0.0
5％、N:0.006％以下を含有し、更にTi及びNbの単独又は
複合添加で、下式（１）に従う有効Ti量（Ti＊と表す）
及びNb量とＣ量との関係が下式（２） Ti＊＝totalTi−｛（48/32）×Ｓ＋（48/14）×Ｎ｝ …
（１） １≦（Ti＊/48＋Nb/93）／（C/12）≦4.5 …（２） を満足する範囲で含有し、必要に応じて更にB:0.0001〜
0.0030％を含有し、残部がFe及び不可避的不純物よりな
る鋼を、1000〜1250℃の範囲で加熱後、熱間圧延を行っ
て（Ar3−50）〜（Ar3＋100）℃の範囲で圧延を終了
し、その後550〜800℃の範囲で巻き取り、これを酸洗し
てトータル圧下率60〜90％の範囲の冷間圧延を行った
後、浸炭雰囲気ガス中で再結晶温度以上の温度で連続焼
鈍を行うことを特徴とする耐２次加工脆性に優れた深絞
り用冷延鋼板の製造方法を要旨とするものである。That is, the present invention, C: 0.007% or less, Mn: 0.05 ~ 0.50
%, P: 0.12% or less, S: 0.015% or less, sol.Al: 0.005 to 0.0
5%, N: 0.006% or less, and by adding Ti and Nb alone or in combination, the effective Ti amount according to the following formula (1) (expressed as Ti *)
And the relationship between the amount of Nb and the amount of C is expressed by the following equation (2) Ti * = totalTi − {(48/32) × S + (48/14) × N} ...
(1) 1 ≦ (Ti * / 48 + Nb / 93) / (C / 12) ≦ 4.5 (2) The content is in the range that satisfies the above condition, and if necessary, further B: 0.0001-
Steel containing 0.0030% and the balance of Fe and unavoidable impurities is heated in the range of 1000 to 1250 ° C and then hot-rolled in the range of (Ar 3 −50) to (Ar 3 +100) ° C. After rolling is finished, it is wound up in the range of 550 to 800 ℃, pickled and cold-rolled in the range of 60 to 90% in total rolling reduction. The gist is a method for producing a cold-rolled steel sheet for deep drawing which is excellent in secondary work embrittlement resistance and which is characterized by performing continuous annealing at a temperature.
以下に本発明を更に詳細に説明する。The present invention will be described in more detail below.
（作用） 本発明は、要するに、前述の如く理論上不可能とされて
いた技術に対して極低炭素鋼を用い、且つ、耐２次加工
脆性のために粒界の欠陥を埋めるのに必要なＣ量２〜15
ppmを確保するならば、連続焼鈍でも可能であることを
見い出したものである。この理由は、Ｃの侵入は粒内拡
散でなく、その速度が10倍程度速い粒界拡散でなされた
ものであり、更に粒界純度の非常に高い極低炭素鋼であ
れば、その拡散速度が更に上がるため、連続焼鈍におい
て、焼鈍前に固溶Ｃ量が零であったものが、まず粒界
に、次いで粒内に所定量のＣ量を確保することができる
ことによるものである。(Operation) The present invention is, in short, required to use the ultra-low carbon steel for the technology that was theoretically impossible as described above, and to fill the grain boundary defects due to the secondary work embrittlement resistance. C amount 2 to 15
It has been found that continuous annealing can be performed if ppm is secured. The reason for this is that the penetration of C is not by intragranular diffusion but by grain boundary diffusion, which is about 10 times faster, and in the case of ultra-low carbon steel with extremely high grain boundary purity, its diffusion rate is This is because, in continuous annealing, the amount of solid solution C was zero before annealing in the continuous annealing, but it is possible to secure a predetermined amount of C in the grain boundaries first and then in the grains.
まず、本発明における鋼の化学成分限定理由について説
明する。First, the reasons for limiting the chemical composition of steel in the present invention will be described.
C: Ｃは、その含有量が増大するにつれてＣを固定するTi、
Nbの添加量が増加し、製造費用の増加につながる。更に
TiC及びNbC析出量が増大し粒成長を阻害をして値が劣化
するので、Ｃ含有量は少ないほどよく、上限値を0.007
％とする。なお、製鋼技術上の観点からＣ含有量の下限
値は0.0005％とするのが望ましい。C: C is Ti that fixes C as its content increases,
The amount of Nb added increases, leading to an increase in manufacturing cost. Further
Since the amount of TiC and NbC precipitation increases, which hinders grain growth and deteriorates the value, the lower the C content, the better.
%. From the viewpoint of steelmaking technology, the lower limit of C content is preferably 0.0005%.
Mn: Mnは熱間脆性の防止を主目的に添加されるが、0.05％よ
り少ないとその効果が得られず、一方、添加量が多すぎ
ると延性を劣化させるので、その含有量は0.05〜0.50％
の範囲とする。Mn: Mn is added mainly for the purpose of preventing hot embrittlement, but if it is less than 0.05%, its effect is not obtained, while if the addition amount is too large, ductility deteriorates, so its content is 0.05- 0.50%
The range is.
P: Ｐは、ｒ値の低下を伴うことなく、鋼強度を高める効果
を有するが、粒界に偏析し２次加工脆性を起こし易くな
るので、その含有量は0.12％以下に抑制する。P: P has the effect of increasing the steel strength without lowering the r value, but segregates at the grain boundaries and easily causes secondary work embrittlement, so the content is limited to 0.12% or less.
S: Ｓは、Tiと結合してTiSを形成するので、その含有量が
増大するとＣ、Ｎを固定するのに必要なTi量が増大す
る。またMnS系の伸長した介在物が増加して局部延性を
劣化させるので、その含有量は0.015％以下に抑制す
る。S: S combines with Ti to form TiS, so if the content thereof increases, the amount of Ti required to fix C and N increases. Further, the MnS-based elongated inclusions increase and deteriorate the local ductility, so the content thereof is suppressed to 0.015% or less.
Al: Alは溶鋼の脱酸を目的に添加されるが、その含有量がso
l.Alで0.005％より少ないと、その目的が達成されず、
一方、0.05％を超えると脱酸効果が飽和すると共にAl2O
3介在物が増加して加工成形性を劣化させる。したがっ
て、その含有量はsol.Alで0.005〜0.05％の範囲とす
る。Al: Al is added for the purpose of deoxidizing molten steel, but its content is
If less than 0.005% in l.Al, the purpose will not be achieved,
On the other hand, if it exceeds 0.05%, the deoxidizing effect is saturated and Al 2 O
3 Inclusions increase and workability deteriorates. Therefore, the content is sol.Al in the range of 0.005 to 0.05%.
N: Ｎは、Tiと結合してTiNを形成するので、その含有量が
増大するとＣを固定するのに必要なTi量が増大する。ま
たTiN析出量が増加して粒成長が阻害されｒ値が劣化す
る。したがって、その含有量は少ないほど好ましく、0.
006％以下に抑制する。N: N combines with Ti to form TiN, so an increase in the content increases the amount of Ti required to fix C. Further, the TiN precipitation amount increases, grain growth is hindered, and the r value deteriorates. Therefore, the smaller the content, the better.
Control to 006% or less.
Ti、Nb: Ti、NbはＣ、Ｎを固定することによってｒ値を高める作
用がある。この場合、前述の如くTiはＳ、Ｎと結合して
TiS、TiNを形成するので、製品におけるTi量は、次式
（１）で計算される有効Ti量（Ti＊）として換算される
量にて考慮する必要がある。Ti, Nb: Ti, Nb has the effect of increasing the r value by fixing C and N. In this case, Ti is combined with S and N as described above.
Since TiS and TiN are formed, it is necessary to consider the Ti amount in the product by the amount converted as the effective Ti amount (Ti *) calculated by the following equation (1).
Ti＊＝totalTi−｛（48/32）×Ｓ＋（48/14）×Ｎ｝ …
（１） したがって、本発明の目的に対してはTi＊量、Nb量とＣ
量との関係が（２）式 １≦（Ti＊/48＋Nb/93）／（C/12）≦4.5 …（２） を満足する範囲で含有する必要がある。この（２）式の
値が１より小さいとＣ、Ｎを充分に固定することができ
ず、ｒ値を劣化させる。一方、4.5を超えるとｒ値を高
める作用が飽和すると共に、後工程の浸炭雰囲気焼鈍時
に侵入したＣが、固溶しているTi或いはNbとすぐに結合
してしまい、Ｃの粒界偏析を阻止するので、耐２次加工
脆性の防止が得られず、また過剰のTi、Nbによる硬化の
ために加工性も劣化し、コストアップもつながる。Ti * = totalTi − {(48/32) × S + (48/14) × N} ...
(1) Therefore, for the purpose of the present invention, Ti * amount, Nb amount and C
It must be contained within the range of the relationship with the amount in the formula (2) 1 ≦ (Ti * / 48 + Nb / 93) / (C / 12) ≦ 4.5 (2). If the value of the equation (2) is smaller than 1, C and N cannot be fixed sufficiently and the r value is deteriorated. On the other hand, if it exceeds 4.5, the action of increasing the r value is saturated, and C that has entered during the annealing in the carburizing atmosphere in the subsequent step is immediately combined with the solid solution Ti or Nb, and the grain boundary segregation of C occurs. Since it prevents it, it is not possible to prevent the secondary work brittleness resistance, and the workability is deteriorated due to hardening by excessive Ti and Nb, which leads to an increase in cost.
B: Ｂは耐２次加工脆性に対して有効な元素であるので、必
要に応じて添加することができる。添加する場合、その
効果を得るためには少なくとも0.0001％以上が必要があ
るが、0.0030％を超えるとその効果は飽和し、且つｒ値
を低下させるので、その添加量は0.0001〜0.0030％の範
囲とする。B: B is an element effective for the secondary work embrittlement resistance, so that it can be added if necessary. If added, at least 0.0001% or more is necessary to obtain the effect, but if it exceeds 0.0030%, the effect is saturated and the r value is lowered, so the addition amount is in the range of 0.0001 to 0.0030%. And
次に本発明の製造方法について説明する。Next, the manufacturing method of the present invention will be described.
上記化学成分を有する鋼は、常法により溶解、鋳造する
が、続く熱間圧延は特定条件にて行う必要がある。The steel having the above chemical composition is melted and cast by a conventional method, but the subsequent hot rolling needs to be performed under specific conditions.
すなわち、1000〜1250℃に加熱した後、仕上温度を（Ar
3−50）〜（Ar3＋100）℃の範囲で熱間圧延を行う。こ
れは、ｒ値向上の観点から熱延板での結晶粒径の細粒化
と集合組織のランダム化が必要であるためであり、必ず
しも仕上温度はAr点以上でなくてもよい。したがって、
仕上温度は（Ar3−50）〜（Ar3＋100）℃の範囲とす
る。That is, after heating to 1000 to 1250 ℃, the finishing temperature (Ar
3 -50) performing hot rolling in a range of ~ (Ar 3 +100) ℃. This is because from the viewpoint of improving the r value, it is necessary to reduce the grain size of the hot-rolled sheet and randomize the texture, and the finishing temperature does not necessarily have to be the Ar point or higher. Therefore,
Finishing temperature is set to (Ar 3 -50) ~ (Ar 3 +100) ℃ range.
熱間圧延後の巻取温度は、鋼中の固溶Ｃ、Ｎを炭窒化物
として固定するために550〜800℃の範囲にする必要があ
る。The coiling temperature after hot rolling needs to be in the range of 550 to 800 ° C. in order to fix the solid solution C and N in the steel as carbonitrides.
次いで、冷間圧延においては、ｒ値に有利な（111）面
方位集合組織を発達させるために、60〜90％のトータル
圧延率で行うことが必要である。Next, in cold rolling, it is necessary to perform at a total rolling rate of 60 to 90% in order to develop a (111) plane orientation texture advantageous for r value.
この冷間圧延後、浸炭雰囲気ガス中で再結晶温度以上の
範囲で連続焼鈍を行い、ｒ値に有利な（111）面方位に
集合組織を形成させる。After this cold rolling, continuous annealing is performed in a carburizing atmosphere gas at a temperature above the recrystallization temperature to form a texture in the (111) plane orientation that is advantageous for the r value.
既に知られているように、ｒ値は主として鋼の（111）
面方位集合組織に依存しているが、本発明において再結
晶焼鈍前に上記巻取処理によって固溶Ｃ及び固溶Ｎを完
全に除くのは、上記の集合組織を得るためである。しか
も、一旦、再結晶が完了し集合組織が形成されれば、そ
の後に侵入するＣはｒ値には悪影響を与えない。浸炭雰
囲気中より侵入したＣのうちTiC、Nbとして固定されな
かったＣが粒界に偏析して耐２次加工脆性を改善するの
である。As is already known, the r value is mainly for steel (111).
Although depending on the plane orientation texture, the solid solution C and the solid solution N are completely removed by the winding treatment before recrystallization annealing in the present invention in order to obtain the above texture. Moreover, once the recrystallization is completed and the texture is formed, C invading thereafter does not adversely affect the r value. Of the C that has entered from the carburizing atmosphere, TiC and C that are not fixed as Nb segregate at the grain boundaries and improve the secondary work embrittlement resistance.
連続焼鈍の雰囲気にはカーボンポテンシャルを制御した
浸炭ガスを用い、目的とする浸炭量はカーボンポテンシ
ャル、焼鈍温度、焼鈍時間の組合せを選択することによ
り制御し、耐２次加工脆性のために粒界の欠陥を埋める
のに必要なＣ量が２〜15ppmとなるような条件で上記連
続焼鈍を行なえばよい。2ppmよりも少ないと耐２次加工
脆性を得るために粒界の欠陥を埋めるのに必要なＣ量が
不足し、一方、15ppmを超えると伸び等の加工性が劣化
し、また連続焼鈍の通板速度を低下させねばならず、生
産性の低下を招くので望ましくない。Carburizing gas with controlled carbon potential is used in the atmosphere of continuous annealing, and the target amount of carburization is controlled by selecting the combination of carbon potential, annealing temperature, and annealing time. The continuous annealing may be carried out under the condition that the amount of C required to fill the defect (2) is 2 to 15 ppm. If it is less than 2 ppm, the amount of C necessary to fill the defects at the grain boundaries in order to obtain resistance to secondary working brittleness is insufficient, while if it exceeds 15 ppm, the workability such as elongation deteriorates, and continuous annealing It is not desirable because the plate speed must be reduced and the productivity is reduced.
連続焼鈍炉の炉内滞留時間は2sec〜2minの範囲が好まし
い。The residence time in the continuous annealing furnace is preferably in the range of 2 sec to 2 min.
次に本発明の実施例を示す。Next, examples of the present invention will be described.
（実施例） 第１表に示す化学成分を有する供試鋼を1250℃で30分間
加熱して溶体化処理を行った後、仕上温度を900℃で熱
間圧延を終了し、その後750℃で巻取り処理を行った。(Example) The sample steel having the chemical composition shown in Table 1 was heated at 1250 ° C for 30 minutes for solution treatment, and then hot rolling was completed at a finishing temperature of 900 ° C, and then at 750 ° C. The winding process was performed.
次いで、酸洗後、圧下率75％で冷間圧延を行い、浸炭雰
囲気ガス中及び不活性ガス中において連続焼鈍として85
0℃で１分間の再結晶焼鈍を行い、約70℃/sの冷却速度
で400℃まで冷却した後、その温度で３分間の過時効処
理を施し、１％のスキンパスを行った。なお、過時効処
理及びスキンパスは、現状の製造工程を想定して行った
ものであり、必要に応じて行えばよい。Then, after pickling, cold rolling is performed at a reduction rate of 75%, and continuous annealing is performed in a carburizing atmosphere gas and an inert gas.
After recrystallization annealing was performed at 0 ° C. for 1 minute, the material was cooled to 400 ° C. at a cooling rate of about 70 ° C./s, then overaged for 3 minutes at that temperature, and 1% skin pass was performed. The overaging treatment and the skin pass are performed assuming the current manufacturing process, and may be performed as necessary.
得られた冷延鋼板の機械的性質と２次加工脆性限界温度
を第２表に示すと共に、一部について第１図〜第３図に
整理して示す。The mechanical properties and the secondary work embrittlement limit temperature of the obtained cold rolled steel sheet are shown in Table 2 and some of them are summarized in FIGS. 1 to 3.
なお、脆性試験は、総絞り比2.7でカッフ成形して得ら
れたカップを35mm高さにトリムした後、各試験温度の冷
媒中にカップを置いて頂角40゜の円錐ポンチに押し込ん
で脆性破壊の発生しない限界温度を測定し、これを２次
加工脆性限界温度とした。In the brittleness test, the cup obtained by cuff molding with a total drawing ratio of 2.7 was trimmed to a height of 35 mm, placed in a refrigerant at each test temperature, and pushed into a conical punch with an apex angle of 40 ° to make it brittle. The critical temperature at which fracture did not occur was measured, and this was taken as the secondary working brittleness critical temperature.
第２表より明らかなとおり、本発明例はいずれも、深絞
り用冷延鋼板としての要求を損ねることなく、耐２次加
工脆性が改善されていることがわかる。As is clear from Table 2, in all the examples of the present invention, the secondary work embrittlement resistance is improved without impairing the requirements as a cold-rolled steel sheet for deep drawing.
一方、不活性ガス中で連続焼鈍を施した比較例は、耐２
次加工脆性に劣っており、また浸炭雰囲気ガス中で連続
焼鈍を行った比較例は、本発明範囲外の化学成分を有し
ているため、プレス成形性或いは耐２次加工脆性のいず
れかが劣っている。On the other hand, the comparative example subjected to continuous annealing in an inert gas is
The comparative example which was inferior in the secondary working brittleness and which was subjected to the continuous annealing in the carburizing atmosphere gas had the chemical composition outside the scope of the present invention, so that either the press formability or the secondary working brittleness resistance was Inferior
なお、第１図はＰ添加量が0.015％以下の鋼において（T
i＊/48＋Nb/93）／（C/12）の値とｒ値との関係を整理
したものであって、（Ti＊/48＋Nb/93）／（C/12）の値
が4.5を超えるとｒ値がほぼ飽和することがわかる。Note that Fig. 1 shows that for steels with a P addition of 0.015% or less (T
The relationship between the value of i * / 48 + Nb / 93) / (C / 12) and the r value is arranged. When the value of (Ti * / 48 + Nb / 93) / (C / 12) exceeds 4.5, It can be seen that the r value is almost saturated.
第２図は第１図の場合と同じ鋼において（Ti＊/48＋Nb/
93）／（C/12）の値と２次加工脆性限界温度との関係を
整理したものであり、本発明範囲内の化学成分を有する
鋼において浸炭雰囲気ガス中で連続焼鈍することによ
り、２次加工脆性限界温度が低下することがわかる。Fig. 2 shows the same steel as in Fig. 1 (Ti * / 48 + Nb /
The relationship between the value of 93) / (C / 12) and the secondary working brittleness limit temperature is arranged, and the steel having a chemical composition within the scope of the present invention is continuously annealed in a carburizing atmosphere gas to obtain 2 It can be seen that the secondary processing brittleness limit temperature decreases.
第３図はＰ添加鋼におけるＰ添加量と２次加工脆性限界
温度との関係を整理したものであり、本発明範囲内のＰ
添加量を有する鋼において浸炭雰囲気ガス中で連続焼鈍
することにより、２次加工脆性限界温度が低下すること
がわかる。FIG. 3 shows the relationship between the amount of P added in P-added steel and the secondary working brittleness limit temperature, and P within the scope of the present invention.
It can be seen that the secondary work embrittlement critical temperature is lowered by continuous annealing in the carburizing atmosphere gas in the steel having the added amount.
（発明の効果） 以上詳述したように、本発明によれば、極低炭素鋼を用
い、且つその化学成分を規制すると共に圧延条件を規制
することにより、連続焼鈍前の固溶Ｃ、Ｎを零として、
次いで浸炭雰囲気ガス中で連続焼鈍を行うので、深絞り
用冷延鋼板として要求されるプレス成形性を損なうこと
なく、耐２次加工脆性に優れた冷延鋼板を得ることがで
き、しかも生産性が高い。 (Effects of the Invention) As described in detail above, according to the present invention, by using ultra-low carbon steel, and controlling the chemical composition thereof and the rolling conditions, the solid solution C, N before continuous annealing can be obtained. Is zero,
Then, since continuous annealing is performed in a carburizing atmosphere gas, it is possible to obtain a cold-rolled steel sheet excellent in secondary work embrittlement resistance without impairing the press formability required as a cold-rolled steel sheet for deep drawing, and also productivity. Is high.
第１図〜第３図は実施例で得られた冷延鋼板の特性を整
理して示す図であり、第１図はＰ添加量が0.015％以下
の鋼の（Ti＊/48＋Nb/93）／（C/12）の値とｒ値との関
係を示し、第２図は上記鋼の（Ti＊/48＋Nb/93）／（C/
12）の値と２次加工脆性限界温度との関係を示し、第３
図はＰ添加鋼におけるＰ添加量と２次加工脆性限界温度
との関係を示している。1 to 3 are diagrams showing the characteristics of the cold-rolled steel sheets obtained in the examples, and FIG. 1 shows the steel (Ti * / 48 + Nb / 93) with a P content of 0.015% or less. Fig. 2 shows the relationship between the value of / (C / 12) and the r value. Fig. 2 shows (Ti * / 48 + Nb / 93) / (C /
The relation between the value of 12) and the secondary working brittleness limit temperature is shown in the third
The figure shows the relationship between the P addition amount and the secondary work embrittlement limit temperature in P-added steel.
Claims (2)
下、Mn:0.05〜0.50％、P:0.12％以下、S:0.015％以下、
sol.Al:0.005〜0.05％、N:0.006％以下を含有し、更にT
i及びNbの単独又は複合添加で、下式（１）に従う有効T
i量（Ti＊と表す）及びNb量とＣ量との関係が下式
（２） Ti＊＝totalTi−｛（48/32）×Ｓ＋（48/14）×Ｎ｝ …
（１） １≦（Ti＊/48＋Nb/93）／（C/12）≦4.5 …（２） を満足する範囲で含有し、残部がFe及び不可避的不純物
よりなる鋼を、1000〜1250℃の範囲で加熱後、熱間圧延
を行って（Ar3−50）〜（Ar3＋100）℃の範囲で圧延を
終了し、その後550〜800℃の範囲で巻き取り、これを酸
洗してトータル圧下率60〜90％の範囲の冷間圧延を行っ
た後、浸炭雰囲気ガス中で再結晶温度以上の温度で連続
焼鈍を行うことを特徴とする耐２次加工脆性に優れた深
絞り用冷延鋼板の製造方法。1. In weight% (hereinafter the same), C: 0.007% or less, Mn: 0.05 to 0.50%, P: 0.12% or less, S: 0.015% or less,
sol.Al: 0.005 to 0.05%, N: 0.006% or less, and T
Effective T according to the following formula (1) when i and Nb are added singly or in combination.
The amount of i (expressed as Ti *) and the relationship between the amount of Nb and the amount of C are expressed by the following equation (2) Ti * = totalTi-{(48/32) × S + (48/14) × N} ...
(1) Steel containing 1 ≦ (Ti * / 48 + Nb / 93) / (C / 12) ≦ 4.5 (2), with the balance being Fe and unavoidable impurities at 1000 to 1250 ° C. After heating in the range, hot rolling is performed to finish the rolling in the range of (Ar 3 -50) to (Ar 3 +100) ° C, and then it is wound in the range of 550 to 800 ° C, pickled and totalized. Cold rolling for deep drawing with excellent secondary work embrittlement resistance, characterized by performing continuous annealing at a temperature above the recrystallization temperature in a carburizing atmosphere gas after cold rolling in the range of 60 to 90% reduction. Manufacturing method of rolled steel sheet.
請求項１に記載の方法。2. The method according to claim 1, wherein the steel contains B: 0.0001 to 0.0030%.
Priority Applications (6)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1230873A JPH0784618B2 (en) | 1989-09-05 | 1989-09-05 | Method for producing cold-rolled steel sheet for deep drawing excellent in secondary processing brittleness resistance |
| DE69014532T DE69014532T2 (en) | 1989-08-09 | 1990-08-08 | Process for the production of a steel sheet. |
| EP90115249A EP0421087B1 (en) | 1989-08-09 | 1990-08-08 | Method of manufacturing a steel sheet |
| CA002022907A CA2022907C (en) | 1989-08-09 | 1990-08-08 | Method of manufacturing a steel sheet |
| KR1019900012246A KR930001519B1 (en) | 1989-08-09 | 1990-08-09 | Method of manufacturing a steel sheet |
| US07/564,756 US5085714A (en) | 1989-08-09 | 1990-08-09 | Method of manufacturing a steel sheet |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1230873A JPH0784618B2 (en) | 1989-09-05 | 1989-09-05 | Method for producing cold-rolled steel sheet for deep drawing excellent in secondary processing brittleness resistance |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0394020A JPH0394020A (en) | 1991-04-18 |
| JPH0784618B2 true JPH0784618B2 (en) | 1995-09-13 |
Family
ID=16914647
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP1230873A Expired - Lifetime JPH0784618B2 (en) | 1989-08-09 | 1989-09-05 | Method for producing cold-rolled steel sheet for deep drawing excellent in secondary processing brittleness resistance |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0784618B2 (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR100470643B1 (en) * | 2000-12-05 | 2005-03-07 | 주식회사 포스코 | A high strength cold rolled steel sheet with excellent drawability and secondary working brittleness resistance, and a method for manufacturing it |
| KR100470644B1 (en) * | 2000-12-06 | 2005-03-07 | 주식회사 포스코 | A method for manufacturing deep drawing cold-rolled steel sheet with excellent secondary working brittleness resistance and press formability |
| KR101149269B1 (en) * | 2009-04-27 | 2012-05-25 | 현대제철 주식회사 | Method for producing of hot-rolled steel sheet having cold rolling |
Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5974232A (en) * | 1982-10-20 | 1984-04-26 | Nippon Steel Corp | Production of bake hardenable galvanized steel sheet for ultradeep drawing having extremely outstanding secondary processability |
| JPS59140333A (en) * | 1983-01-28 | 1984-08-11 | Nippon Steel Corp | Manufacture of cold rolled steel sheet for deep drawing with superior secondary workability and surface treatability |
| JPS60149729A (en) * | 1984-01-11 | 1985-08-07 | Kawasaki Steel Corp | Production of cold rolled steel sheet for press forming |
| JPS61119621A (en) * | 1984-11-16 | 1986-06-06 | Nippon Steel Corp | Manufacture of cold rolled steel sheet for deep drawing |
| JPS6237341A (en) * | 1985-08-12 | 1987-02-18 | Kawasaki Steel Corp | Hot-rolled steel plate for superdrawing having superior resistance to secondary operation brittleness |
| JPS6338556A (en) * | 1986-08-04 | 1988-02-19 | Nisshin Steel Co Ltd | Cold rolled steel sheet for deep drawing having superior resistance to cracking by secondary working and its manufacture |
| JPS6386819A (en) * | 1986-09-30 | 1988-04-18 | Kawasaki Steel Corp | Production of cold rolled steel sheet for deep drawing |
-
1989
- 1989-09-05 JP JP1230873A patent/JPH0784618B2/en not_active Expired - Lifetime
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5974232A (en) * | 1982-10-20 | 1984-04-26 | Nippon Steel Corp | Production of bake hardenable galvanized steel sheet for ultradeep drawing having extremely outstanding secondary processability |
| JPS59140333A (en) * | 1983-01-28 | 1984-08-11 | Nippon Steel Corp | Manufacture of cold rolled steel sheet for deep drawing with superior secondary workability and surface treatability |
| JPS60149729A (en) * | 1984-01-11 | 1985-08-07 | Kawasaki Steel Corp | Production of cold rolled steel sheet for press forming |
| JPS61119621A (en) * | 1984-11-16 | 1986-06-06 | Nippon Steel Corp | Manufacture of cold rolled steel sheet for deep drawing |
| JPS6237341A (en) * | 1985-08-12 | 1987-02-18 | Kawasaki Steel Corp | Hot-rolled steel plate for superdrawing having superior resistance to secondary operation brittleness |
| JPS6338556A (en) * | 1986-08-04 | 1988-02-19 | Nisshin Steel Co Ltd | Cold rolled steel sheet for deep drawing having superior resistance to cracking by secondary working and its manufacture |
| JPS6386819A (en) * | 1986-09-30 | 1988-04-18 | Kawasaki Steel Corp | Production of cold rolled steel sheet for deep drawing |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0394020A (en) | 1991-04-18 |
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