JP2816592B2 - Manufacturing method of cold-rolled steel sheet for deep drawing with excellent bake hardenability - Google Patents
Manufacturing method of cold-rolled steel sheet for deep drawing with excellent bake hardenabilityInfo
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- JP2816592B2 JP2816592B2 JP13522590A JP13522590A JP2816592B2 JP 2816592 B2 JP2816592 B2 JP 2816592B2 JP 13522590 A JP13522590 A JP 13522590A JP 13522590 A JP13522590 A JP 13522590A JP 2816592 B2 JP2816592 B2 JP 2816592B2
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- cold
- steel sheet
- less
- bake hardenability
- rolling
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- Heat Treatment Of Sheet Steel (AREA)
Description
【発明の詳細な説明】 (産業上の利用分野) 近年、自動車業界では排気ガスとして大気中に排出さ
れるCO2を大幅に削減するため、車体軽量化がますます
推進される状況にあり、パネル用鋼板とくに外板用鋼板
は板厚の薄手化が進められている。しかしながら、板厚
の減少はプレス成形後の形状変化をきたす恐れがある。
そのためパネル用鋼板としてはプレス成形後の形状を維
持しかつ、耐デント性が要求される。本発明はこうした
要求に応えるため、上記特性が必要とされる部位に使用
して好適な、プレス成形後の塗装焼付により強度を高め
る特性、すなわち焼付硬化性に優れかつ、車体デザイン
の多用化にも対応できうる優れた深絞り性をも兼ね備え
た冷延鋼板の製造方法に関するものである。[Detailed Description of the Invention] (Industrial application field) In recent years, the automobile industry has been in a situation where vehicle weight reduction has been increasingly promoted in order to significantly reduce CO 2 emitted into the atmosphere as exhaust gas. Thinner steel sheets for panels, especially for outer panels, are being developed. However, a decrease in the plate thickness may cause a change in shape after press forming.
Therefore, a steel sheet for a panel is required to maintain the shape after press forming and to have dent resistance. In order to meet such demands, the present invention is suitable for use in parts where the above properties are required, and is a property that enhances strength by paint baking after press molding, that is, excellent in bake hardenability, and is used for versatile body design. The present invention relates to a method for producing a cold-rolled steel sheet having excellent deep drawability that can also be applied.
(従来の技術) 自動車パネル用冷延鋼板は、車体軽量化の観点から高
強度化が進んでいる。こうした動きの中で、鋼板そのも
のの強度を上げるばかりでなく、優れた成形性を兼ね備
えたまま、成形時は軟質でありながらプレス成形後の塗
装焼付により鋼板を高強度化する、焼付硬化型の冷延鋼
板の開発が進められている。成形性とともに優れた焼付
硬化性を兼ね備えた冷延鋼板の製造方法としては、これ
までに、(1)特開昭57−192225号公報及び(2)特開
昭62−83426公報に開示されている技術がある。(Prior Art) The strength of cold rolled steel sheets for automobile panels has been increasing from the viewpoint of reducing the weight of the vehicle body. In such movements, not only increase the strength of the steel sheet itself, but also have excellent formability, while being soft at the time of forming, the baking hardening type that increases the strength of the steel sheet by paint baking after press forming Development of cold rolled steel sheets is underway. A method for producing a cold rolled steel sheet having both good formability and excellent bake hardenability has been disclosed in (1) JP-A-57-192225 and (2) JP-A-62-83426. Technology.
(1)ではTi,V,Nbの複合添加により炭化物の析出量
増加を招き、硬質化が懸念される。また、実際にはC量
が多いため焼付硬化量が高い反面、AIがせいぜい3kgf/m
m2で完全に非時効とは言えない。さらに、r値も1.8程
度で加工性としても十分とはいえない。一方、(2)で
はV,Tiを添加して固溶Cを極力減らすとともに、VC及び
VNを析出させることにより焼鈍後の再結晶集合組織を制
御することで深絞り性を高めたものである。しかしなが
ら、焼鈍後の冷却速度を規制したものではなく、積極的
に焼鈍後の冷却速度を規制し、高い深絞り性を確保しな
がら4kgf/mm2以上の焼付硬化性を付与する本発明とは目
的が異なる。In the case of (1), the combined addition of Ti, V, and Nb causes an increase in the amount of precipitated carbide, and there is a concern about hardening. In addition, the baking hardening amount is high due to the large amount of C, but AI is at most 3 kgf / m
m 2 is not completely non-aging. Further, the r value is about 1.8, which is not sufficient for workability. On the other hand, in (2), V and Ti are added to reduce solid solution C as much as possible, and VC and
The deep drawability is enhanced by controlling the recrystallization texture after annealing by precipitating VN. However, not that with regulating the cooling rate after annealing, the present invention to impart actively cooling rate after annealing regulated, while ensuring a high deep drawability 4 kgf / mm 2 or more bake hardenability The purpose is different.
(発明が解決しようとする課題) このように極低炭素鋼を用い、成形性と焼付硬化性に
優れた冷延鋼板を製造する方法はすでに開示されている
が、現状自動車業界の要求を満足するには、成形性及び
焼付硬化性ともにいまだ十分とは言えない。したがっ
て、さらに優れた成形性と焼付硬化性を有する、具体的
には2.2以上のr値と4kgf/mm2以上の焼付硬化性を有す
る冷延鋼板の製造方法を確立することが、本発明の目的
である。(Problems to be Solved by the Invention) As described above, a method of manufacturing a cold-rolled steel sheet excellent in formability and bake hardenability using an ultra-low carbon steel has already been disclosed, but it satisfies the requirements of the current automobile industry. However, both moldability and bake hardenability are not yet satisfactory. Therefore, to have a more excellent formability and bake hardenability, specifically to establish a method of manufacturing a cold rolled steel sheet having an r value of 2.2 or more and bake hardenability of 4 kgf / mm 2 or more, the present invention Is the purpose.
(課題を解決するための手段) 本発明者らは、上記実情に鑑み鋭意検討した結果、極
低炭素鋼にV及びTiを複合添加した再結晶焼鈍後の冷却
速度を制限することで、深絞り性及び焼付硬化性に優れ
た冷延鋼板の製造方法を見いだしたのである。(Means for Solving the Problems) As a result of intensive studies in view of the above circumstances, the present inventors have found that by limiting the cooling rate after recrystallization annealing in which V and Ti are added to ultra-low carbon steel in combination, the They have found a method for producing a cold rolled steel sheet having excellent drawability and bake hardenability.
第1図に本発明の確立に至った実験結果を示す。本実
験ではC及びN量を0.002wt%とし、V及びTi量を種々
の水準変化させた鋼を真空溶解で溶製した。それらの鋼
についてAr3点以上の仕上温度で熱延後600℃で巻取っ
た。これを酸洗・冷却後、850℃で再結晶焼鈍してから8
0℃/sで室温まで冷却してから1%の調質圧延を行な
い、焼付硬化量(2%の予歪を与えて170℃で20分の保
定を行なったときの熱処理前後での降伏点応力の上昇
量)を調査した。すなわち、VとTiの添加量により焼付
硬化量が変化することを見いだしたのである。こうした
現象が生じる原因については明確ではないが、VC及びTi
Cの析出が関与しているものと考えられる。つまり、TiC
に比べて固溶限の広いVCを利用することで再結晶焼鈍後
にも固溶Cを残存させ、焼付硬化性を付与することがで
きる。本発明はVとTiを複合添加した極低炭素鋼におい
て、それらの添加量と再結晶焼鈍後の冷却速度を適切に
とることで焼付硬化性を付与するものである。FIG. 1 shows the experimental results that led to the establishment of the present invention. In this experiment, steels with C and N contents of 0.002 wt% and V and Ti contents of various levels were melted by vacuum melting. These steels were rolled at 600 ° C. after hot rolling at a finishing temperature of at least 3 points of Ar. This is pickled and cooled, and then recrystallized and annealed at 850 ° C.
After cooling to room temperature at 0 ° C / s, pass 1% temper rolling, bake hardening (Yield point before and after heat treatment when holding at 170 ° C for 20 minutes with 2% prestrain) The amount of increase in stress) was investigated. That is, it has been found that the bake hardening amount changes depending on the added amounts of V and Ti. The cause of this phenomenon is not clear, but VC and Ti
It is considered that C precipitation is involved. In other words, TiC
By using VC having a wider solid solution limit than that of the above, solid solution C can be left even after recrystallization annealing, and bake hardenability can be imparted. The present invention is intended to impart bake hardenability to an ultra-low carbon steel to which V and Ti are added in combination by appropriately setting the amount of addition and the cooling rate after recrystallization annealing.
つまり、本発明は次のように構成したものである。 That is, the present invention is configured as follows.
C:0.003wt%以下、Si:1.5wt%以下、Mn:0.01〜2.0wt
%、P:0.15wt%以下、S:0.01wt%以下、Al:0.01〜0.1wt
%、N:0.005wt%以下、Ti:〔N(wt%)〕×(48/14)
〜0.02wt%を含むほか、V:(〔C(wt%)〕−〔T
1 *(wt%)〕×(12/48))×(51/12)〜0.1wt%を含
有し、残部はFe及び不可避的不純物元素からなる鋼を連
続鋳造にてスラブとした後、再加熱あるいは鋳造後直ち
にAr3点以上の温度で仕上熱延を終了して600℃以上の温
度で巻取、酸洗後通常の方法で冷間圧延を行ない、連続
焼鈍にて800℃以上850℃以下の温度域で1秒以上の再結
晶焼鈍を施した後、70℃/s以上の冷却速度で冷却し、さ
らに調質圧延を行なうことを特徴とする焼付硬化性の優
れた深絞り用冷延鋼板の製造方法、 〔T1 *〕=total〔Ti〕−〔Ti as TiN〕 である。C: 0.003 wt% or less, Si: 1.5 wt% or less, Mn: 0.01 to 2.0 wt
%, P: 0.15 wt% or less, S: 0.01 wt% or less, Al: 0.01 to 0.1 wt%
%, N: 0.005 wt% or less, Ti: [N (wt%)] x (48/14)
V: ([C (wt%)]-[T
1 * (wt%)] × (12/48)) × (51/12) ~ 0.1wt%, the balance being steel consisting of Fe and unavoidable impurity elements. Immediately after heating or casting, finish hot rolling at a temperature of Ar 3 or higher, wind up at a temperature of 600 ° C or higher, perform pickling, perform cold rolling by a usual method, and perform continuous annealing at 800 ° C to 850 ° C. After recrystallization annealing for 1 second or more in the following temperature range, it is cooled at a cooling rate of 70 ° C / s or more, and then temper rolling is performed. The manufacturing method of the rolled steel sheet, [T 1 * ] = total [Ti] − [Ti as TiN].
まず、本発明における化学成分の限定理由について述
べる。First, the reasons for limiting the chemical components in the present invention will be described.
Cは、本発明における焼付硬化性の付与に対して重要
な役割を果たす元素である。常温における成形性、すな
わち低YP、高El及び高r値を確保しかつ、非時効とする
にはその添加量は低いほうが良い。そのため上限を0.00
3wt%とする。C is an element that plays an important role in imparting bake hardenability in the present invention. To ensure moldability at room temperature, that is, low YP, high El and high r value, and to make it non-aging, it is better that the amount of addition is low. Therefore the upper limit is 0.00
3 wt%.
Siは、鋼を高強度化する場合に添加されるが、過度の
添加は鋼を硬質化させるとともに溶接性を劣化させる。
また、鋼の表面性状を良好とするためにはその添加量は
少ない方が良く、上限を1.5wt%とする。Si is added to increase the strength of steel, but excessive addition hardens the steel and deteriorates the weldability.
In order to improve the surface properties of the steel, the smaller the amount, the better. The upper limit is 1.5 wt%.
Mnも鋼の高強度化に有効に寄与するが、過度の添加は
鋼を硬質化させるため2.0wt%を上限として添加する。
なお、Mn量が少ない場合は熱間割れを招くため、下限を
0.01wt%とする。Mn also effectively contributes to increasing the strength of the steel, but excessive addition causes 2.0% by weight of the upper limit to be added to harden the steel.
When the amount of Mn is small, hot cracking is caused.
0.01 wt%.
Pは、Si、Mnに比べ固溶強化能の大きな元素であると
ともに、添加による延性及び深絞り性の劣化が少ない元
素であるために、成形性を確保しつつ強度を上昇させる
のに重要な元素である。本発明においても高強度化を目
的とする場合には添加されるが、過度の添加は鋼の硬質
化につながり、成形性を劣化させるばかりでなくPの粒
界偏析による二次加工性の劣化を招くため、上限を0.15
wt%とする。P is an element having a large solid solution strengthening ability as compared with Si and Mn, and is an element that hardly deteriorates in ductility and deep drawability due to addition, so it is important to increase strength while securing formability. Element. Also in the present invention, it is added for the purpose of increasing the strength, but excessive addition leads to hardening of the steel, not only deteriorating the formability but also deteriorating the secondary workability due to segregation of P at the grain boundary. 0.15
wt%.
Sは過剰に添加されると熱間割れを招くため0.01wt%
以下とするが、脱硫コストの上昇などの問題から0.003w
t%以上が好ましい。If S is excessively added, it causes hot cracking.
However, due to problems such as increased desulfurization costs, 0.003w
t% or more is preferable.
Alは、鋼の脱硫のために必要であり、Tiの歩留を向上
させるため0.01wt%以上必要である。一方、過剰の添加
はコストアップとなるとともに鋼中に介在物を残すこと
になるため、上限は0.1wt%とする。Al is necessary for desulfurization of steel, and 0.01 wt% or more is required for improving the yield of Ti. On the other hand, excessive addition increases the cost and leaves inclusions in the steel, so the upper limit is 0.1 wt%.
Nは、熱延段階までにTiで固定されるため、多量のTi
Nが形成されると加工性の劣化を招くため、上限を0.005
wt%とする。好ましくは0.003wt%以下がよい。N is fixed by Ti by the hot rolling stage, so a large amount of Ti
Since the formation of N causes deterioration in workability, the upper limit is 0.005.
wt%. Preferably, the content is 0.003 wt% or less.
Tiは通常C,N及びSを固定するために添加されるが、
本発明ではVを複合添加するとともに、S量を低く規制
するのでNを完全に固定できる量が下限となる。すなわ
ち、〔Nwt%〕×(48/14)以上とする。一方、Ti量が増
えると焼付硬化性が減少し、0.02wt%を超えると焼付硬
化性が失われるため、上限を0.02wt%とする。Ti is usually added to fix C, N and S,
In the present invention, since V is added in combination and the amount of S is regulated to be low, the amount that can completely fix N is the lower limit. That is, it is set to [Nwt%] × (48/14) or more. On the other hand, if the amount of Ti increases, bake hardenability decreases, and if it exceeds 0.02 wt%, bake hardenability is lost, so the upper limit is made 0.02 wt%.
Vは、本発明において最も重要な役割を果たす元素で
ある。すなわち、固溶限の広いVCの析出を利用すること
で、最結晶焼鈍中に再溶解させるとともに焼鈍後にも十
分な焼付硬化性が得られる程度の固溶C量を残存させる
ことができる。こうしたVCの特性を効率よく発揮するに
は、TiやSで固定されたC以外のCをすべて固定できる
ぐらいの添加量が必要となる。少ないと固溶Cを過剰に
残すことになり、時効性を劣化させる原因となる。した
がって{(〔Cwt%〕−〔T1 *(wt%)〕×(12/48))
×(51/12)}以上とする。また、過剰に添加しても効
果は飽和するため上限を0.1wt%とする。V is an element that plays the most important role in the present invention. In other words, by utilizing the precipitation of VC having a wide solid solubility limit, it is possible to re-dissolve during the recrystallization annealing and to leave a sufficient amount of solid solution C to obtain sufficient bake hardenability after annealing. In order to efficiently exhibit such VC characteristics, it is necessary to have an added amount that can fix all C other than C fixed by Ti or S. If the amount is small, solid solution C is left excessively, which causes deterioration of aging property. Therefore {([Cwt%] - [T 1 * (wt%)] × (12/48))
× (51/12)} or more. The effect is saturated even if it is added excessively, so the upper limit is made 0.1 wt%.
なお、本発明ではとくに規定しないが、Nb,Mo,Cr,Wあ
るいはCa,Zr,Ce等の希土類元素を添加してもさしつかえ
ない。Although not particularly specified in the present invention, a rare earth element such as Nb, Mo, Cr, W or Ca, Zr, Ce may be added.
次に、本発明に従う製造方法について説明する。上述
した化学成分を有する鋼は通常の連続鋳造にてスラブと
して得られるが、薄スラブ連鋳法にて製造されたもので
もかまわない。さらに、Ar3点以上の仕上温度で熱間圧
延を行ない、600℃以上の温度域で巻取るが、これより
低い温度で巻取る熱延板段階でCの析出が不十分とな
り、冷延・焼鈍後のr値の劣化を招く。しかし、酸洗性
を考慮し800℃以下が好ましい。続いて通常の酸洗及び
冷間圧延によって冷延板とする。Next, a manufacturing method according to the present invention will be described. The steel having the above-described chemical components is obtained as a slab by ordinary continuous casting, but may be manufactured by a thin slab continuous casting method. Furthermore, hot rolling is performed at a finishing temperature of 3 points or more of Ar and winding is performed in a temperature range of 600 ° C. or more. This leads to deterioration of the r value after annealing. However, the temperature is preferably 800 ° C. or less in consideration of pickling properties. Subsequently, a cold-rolled sheet is formed by ordinary pickling and cold rolling.
再結晶焼鈍は、延性及び深絞り性を確保するため再結
晶や粒成長を十分行なわせると同時に、焼付硬化性を付
与するためVCを再溶解させる目的で800℃以上の温度域
で1秒以上保持するものとする。850℃を超える温度で
は変態に伴う集合組織の劣化によるr値の低下や結晶粒
の粗大化による肌荒れの原因となるため好ましくない。Recrystallization annealing is performed for 1 second or more at a temperature range of 800 ° C or higher for the purpose of recrystallizing and growing grains sufficiently to secure ductility and deep drawability, and to re-dissolve VC to impart bake hardenability. Shall be retained. A temperature exceeding 850 ° C. is not preferable because it causes a decrease in the r value due to the deterioration of the texture due to the transformation and a rough surface due to the coarsening of the crystal grains.
再結晶焼鈍後の冷却は焼付硬化性を付与するための固
溶Cを十分に残す程度の冷却速度が必要である。すなわ
ち、70℃/s以下の冷却速度では焼鈍中に再固溶したCが
再析出し、4kgf/mm2以上の焼付硬化性が得られない。な
お、冷却は途中で中断し200〜400℃の温度域で過時効処
理を施しても本質的な差はない。Cooling after recrystallization annealing requires a cooling rate sufficient to leave solid solution C for imparting bake hardenability. That is, at a cooling rate of 70 ° C./s or less, C re-dissolved during annealing is re-precipitated, and a bake hardenability of 4 kgf / mm 2 or more cannot be obtained. In addition, there is no essential difference even if cooling is interrupted on the way and overaged in the temperature range of 200 to 400 ° C.
(実施例) 実施例1 C:0.0021wt%,Si:0.20wt%,Mn:0.15wt%,P:0.011wt
%,S:0.007wt%,Al:0.028wt%,N:0.0015wt%,Ti:0.011w
t%,V:0.010wt%、残部Fe及び不可避的不純物からなる
鋼を転炉出鋼し、連続鋳造でスラブにした。熱延は1100
℃で加熱後仕上温度を930℃とし、600℃で巻取った。酸
洗後80%の圧下率で冷間圧延を施し、第1表に示すよう
な条件で再結晶焼鈍及び冷却後、1%の調質圧延を行な
った。その後材質評価としてJIS Z 2201,5号試験片に加
工し、同2241記載の試験方法にしたがって引張試験を行
なった。焼付硬化量(BH)については、2%の予歪を与
えて170℃で20分の保定を行なったときの処理前後での
降伏点応力の上昇量で表した。また、時効性については
100℃で60分の保定後引張試験を行ない、降伏点伸びの
程度で評価した。第2表に結果をまとめて示す。(Example) Example 1 C: 0.0021 wt%, Si: 0.20 wt%, Mn: 0.15 wt%, P: 0.011 wt
%, S: 0.007wt%, Al: 0.028wt%, N: 0.0015wt%, Ti: 0.011w
A steel containing t%, V: 0.010 wt%, the balance being Fe and unavoidable impurities was output from a converter and made into a slab by continuous casting. Hot rolling is 1100
After heating at ℃, the finishing temperature was 930 ° C, and the film was wound at 600 ° C. After pickling, cold rolling was performed at a rolling reduction of 80%, recrystallization annealing and cooling were performed under the conditions shown in Table 1, and then 1% temper rolling was performed. Thereafter, as a material evaluation, the test piece was processed into a JIS Z 2201, No. 5 test piece, and a tensile test was performed in accordance with the test method described in 2421. The bake hardening amount (BH) was expressed as an increase in yield point stress before and after the treatment when a pre-strain of 2% was given and the temperature was held at 170 ° C. for 20 minutes. Regarding aging,
After holding at 100 ° C. for 60 minutes, a tensile test was performed, and the degree of elongation at the yield point was evaluated. Table 2 summarizes the results.
再結晶焼鈍及び冷却条件が本発明の範囲に従ったNo.
2,3及び4は2.2以上のr値と4kgf/mm2以上のBHを有し、
しかも時効性についても問題のない材質が得られる。N
o.1は再結晶させるための温度が低く、若干硬質気味で
あると同時にVCの再溶解が少ないためBHがほとんどな
い。再結晶焼鈍後の冷却速度が低くはずれたNo.5及び6
は、冷却中にVCが析出して固溶Cの残存量が不足するた
め、2kgf/mm2程度のBHしか得られていない。No.7は再結
晶焼鈍の温度が高くはずれたため、結晶粒が粗大化する
とともに集合組織が劣化し、引張試験後に肌荒れが生
じ、r値が低い。Recrystallization annealing and cooling conditions according to the scope of the present invention No.
2,3 and 4 have r value of 2.2 or more and BH of 4 kgf / mm 2 or more,
Moreover, a material having no problem with aging can be obtained. N
o.1 has a low temperature for recrystallization, is slightly hard, and has little BH due to little re-dissolution of VC. Nos. 5 and 6 where the cooling rate after recrystallization annealing was low
In the case of B, only BH of about 2 kgf / mm 2 was obtained because VC precipitated during cooling and the amount of residual solid solution C was insufficient. In No. 7, since the recrystallization annealing temperature was too high, the crystal grains became coarse and the texture deteriorated, and after the tensile test, the surface became rough and the r-value was low.
実施例2 第3表に示した化学成分の鋼を転炉出鋼し、連続鋳造
でスラブとした後、通常の熱延及び冷延を施し、再結晶
焼鈍及び冷却条件は本発明の範囲で一定とした。すなわ
ち、熱延は1150℃で加熱した後、910℃で仕上げ圧延を
終了した。酸洗後80%の冷間圧延を施し、再結晶焼鈍は
850℃で60sとし、100℃/sで300℃まで冷却しその温度で
5分の保定後室温に冷却した。続いて1%の調質圧延を
行なってから、実施例1と同じ方法で材質評価を行なっ
た。第4表に結果をまとめて示す。Example 2 A steel having the chemical composition shown in Table 3 was output from a converter and made into a slab by continuous casting, and then subjected to ordinary hot rolling and cold rolling. Recrystallization annealing and cooling conditions were within the scope of the present invention. It was fixed. That is, after hot rolling at 1150 ° C., finish rolling at 910 ° C. was completed. 80% cold rolling after pickling, recrystallization annealing
The temperature was set to 60 s at 850 ° C., cooled to 300 ° C. at 100 ° C./s, kept at that temperature for 5 minutes, and cooled to room temperature. Subsequently, after temper rolling of 1% was performed, the material evaluation was performed in the same manner as in Example 1. Table 4 summarizes the results.
本発明の範囲に従ったA,B,C,D及びE鋼のNo.2,3,5,7
及び8は2.2以上のr値と4kgf/mm2以上のBHを有し、し
かも時効性についても問題のない材質が得られる。No.
1,4及び6は本発明に従った成分の鋼であるが、巻取温
度がいずれも600℃未満と低いため熱延板で固溶Cが残
存し、冷延・焼鈍後のr値が低い。C及びN量が本発明
の範囲から高くはずれたF鋼(No.9)では冷延・焼鈍後
のr値が十分に高くない。G鋼はTi量が本発明の範囲か
ら高くはずれたため、BHがほとんどない。また、H鋼は
逆にTi量が低すぎてNを十分に固定できず、冷延・焼鈍
後の時効性が劣る。I鋼はVが添加されていないため、
VCの析出がなくBHが全く得られない。Nos. 2, 3, 5, 7 of A, B, C, D and E steels according to the scope of the present invention
And No. 8 have an r value of 2.2 or more and a BH of 4 kgf / mm 2 or more, and a material having no problem with aging can be obtained. No.
1, 4 and 6 are steels having components according to the present invention. However, since the winding temperature is as low as less than 600 ° C., solid solution C remains in the hot-rolled sheet, and the r-value after cold rolling and annealing is low. Low. In steel F (No. 9) in which the C and N contents are outside the range of the present invention, the r value after cold rolling and annealing is not sufficiently high. The G steel has almost no BH because the Ti content deviated from the range of the present invention. On the other hand, the H steel, on the other hand, has too low a Ti content to fix N sufficiently, resulting in poor aging after cold rolling and annealing. Since steel I has no added V,
There is no precipitation of VC and no BH can be obtained.
(発明の効果) 本発明は、自動車のパネル用鋼板とくに外板用鋼板と
して使用される鋼板に対し、優れた深絞り性を維持しな
がら成形後の塗装焼付により強度を高めることができる
冷延鋼板の製造方法を明らかにしたものである。この発
明によりプレス成形後の鋼板の高強度化が可能となると
同時に、鋼板の薄手化が実現され車体の軽量化が可能と
なる。 (Effects of the Invention) The present invention provides a cold rolled steel sheet that can increase the strength of a steel sheet for automobile panels, particularly a steel sheet used for an outer panel, by baking paint after forming while maintaining excellent deep drawability. This clarifies the method of manufacturing a steel sheet. According to the present invention, it is possible to increase the strength of the steel sheet after press forming, and at the same time, it is possible to reduce the thickness of the steel sheet and reduce the weight of the vehicle body.
第1図は、Ti及びVの本発明範囲を示す説明図である。 FIG. 1 is an explanatory diagram showing the present invention range of Ti and V.
フロントページの続き (56)参考文献 特開 昭61−246327(JP,A) 特開 昭61−276931(JP,A) (58)調査した分野(Int.Cl.6,DB名) C21D 9/46 - 9/48 C21D 8/02 - 8/04Continuation of the front page (56) References JP-A-61-246327 (JP, A) JP-A-61-276931 (JP, A) (58) Fields investigated (Int. Cl. 6 , DB name) C21D 9 / 46-9/48 C21D 8/02-8/04
Claims (1)
01〜2.0wt%、P:0.15wt%以下、S:0.01wt%以下、Al:0.
01〜0.1wt%、N:0.005wt%以下、Ti:〔N(wt%)〕×
(48/14)〜0.02wt%を含むほか、V:{〔C(wt%)−
[Ti*(wt%)〕×(12/48)}×(51/12)〜0.1wt%
を含有し、残部はFe及び不可避的不純物元素からなる鋼
を連続鋳造にてスラブとした後、再加熱あるいは鋳造後
直ちにAr3点以上の温度で仕上熱延を終了して600℃以上
の温度で巻取、酸洗後通常の方法で冷間圧延を行ない、
連続焼鈍にて800℃以上850℃以下の温度域で1秒以上の
再結晶焼鈍を施した後、70℃/s以上の冷却速度で冷却
し、さらに調質圧延を行なうことを特徴とする焼付硬化
性の優れた深絞り用冷延鋼板の製造方法。C: 0.003 wt% or less, Si: 1.5 wt% or less, Mn: 0.
01 ~ 2.0wt%, P: 0.15wt% or less, S: 0.01wt% or less, Al: 0.
01 to 0.1 wt%, N: 0.005 wt% or less, Ti: [N (wt%)] ×
(48/14) to 0.02wt%, V: {[C (wt%)-
[Ti * (wt%)] × (12/48)} × (51/12) ~ 0.1wt%
, And the remainder is made of steel consisting of Fe and unavoidable impurity elements, made into a slab by continuous casting, and finished hot rolling at a temperature of 3 points or more immediately after reheating or casting, and a temperature of 600 ° C or more. After rolling, pickling and cold rolling in the usual way,
After recrystallization annealing in the temperature range of 800 ° C or more and 850 ° C or less for 1 second or more by continuous annealing, it is cooled at a cooling rate of 70 ° C / s or more, and further temper rolling is performed. Manufacturing method of cold-rolled steel sheet for deep drawing with excellent curability.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP13522590A JP2816592B2 (en) | 1990-05-28 | 1990-05-28 | Manufacturing method of cold-rolled steel sheet for deep drawing with excellent bake hardenability |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP13522590A JP2816592B2 (en) | 1990-05-28 | 1990-05-28 | Manufacturing method of cold-rolled steel sheet for deep drawing with excellent bake hardenability |
Publications (2)
Publication Number | Publication Date |
---|---|
JPH0432519A JPH0432519A (en) | 1992-02-04 |
JP2816592B2 true JP2816592B2 (en) | 1998-10-27 |
Family
ID=15146741
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP13522590A Expired - Fee Related JP2816592B2 (en) | 1990-05-28 | 1990-05-28 | Manufacturing method of cold-rolled steel sheet for deep drawing with excellent bake hardenability |
Country Status (1)
Country | Link |
---|---|
JP (1) | JP2816592B2 (en) |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH05263146A (en) * | 1992-03-17 | 1993-10-12 | Nippon Steel Corp | Manufacture of cold rolled steel sheet for deep drawing excellent in baking hardenability |
CN114959427A (en) * | 2022-05-18 | 2022-08-30 | 包头钢铁(集团)有限责任公司 | Manufacturing method of 180 MPa-grade ultra-low carbon baking hardened steel for automobile |
-
1990
- 1990-05-28 JP JP13522590A patent/JP2816592B2/en not_active Expired - Fee Related
Also Published As
Publication number | Publication date |
---|---|
JPH0432519A (en) | 1992-02-04 |
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