JPH07138699A - Steel plate, excellent in spot weldability and surface characteristic, and its production - Google Patents
Steel plate, excellent in spot weldability and surface characteristic, and its productionInfo
- Publication number
- JPH07138699A JPH07138699A JP17854294A JP17854294A JPH07138699A JP H07138699 A JPH07138699 A JP H07138699A JP 17854294 A JP17854294 A JP 17854294A JP 17854294 A JP17854294 A JP 17854294A JP H07138699 A JPH07138699 A JP H07138699A
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- Prior art keywords
- slab
- less
- spot weldability
- steel sheet
- steel plate
- 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.)
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- Heat Treatment Of Steel (AREA)
- Heat Treatment Of Sheet Steel (AREA)
Abstract
Description
【0001】[0001]
【産業上の利用分野】本発明は、自動車用など良好なス
ポット溶接性が要求される用途に対し好適な鋼板、即
ち、熱間圧延板、その表面処理鋼板、冷延鋼板、及びそ
の表面処理鋼板、及び、これらの製造方法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steel sheet suitable for applications requiring good spot weldability such as automobiles, that is, a hot rolled sheet, its surface treated steel sheet, cold rolled steel sheet, and its surface treatment. TECHNICAL FIELD The present invention relates to a steel plate and a manufacturing method thereof.
【0002】[0002]
【従来の技術】従来、高いプレス成形性を有する鋼板を
製造するための方策として、特公昭44−18066号
公報、特公昭54−1245号公報、特開昭59−67
319号公報、などに開示されている、いわゆるIF
鋼、即ち、鋼中の窒素および炭素を極力低減し、Tiや
Nbなどの炭窒化物形成元素を添加した鋼が広く使用さ
れるようになってきている。2. Description of the Related Art Conventionally, as a measure for producing a steel sheet having high press formability, Japanese Patent Publication No. 44-18066, Japanese Patent Publication No. 54-1245, and Japanese Patent Laid-Open No. 59-67.
So-called IF disclosed in Japanese Patent No. 319, etc.
Steel, that is, steel in which nitrogen and carbon in the steel are reduced as much as possible and carbonitride forming elements such as Ti and Nb are added, has been widely used.
【0003】しかし、IF鋼は極低炭素鋼のためにスポ
ット溶接熱影響部の結晶粒が粗大化しやすく、スポット
溶接継手の強度が低いといった問題がある。そこで、鋼
中の酸素量を規定した特開平3−177538号公報、
Ti−Nb−B量を規定した特開昭63−317625
号公報、特開昭63−317648号公報、特開昭63
−317649号公報、さらには、Ti析出物の寸法と
量を規定した特開昭63−317647号公報等があ
る。However, since the IF steel is an ultra-low carbon steel, the crystal grains in the spot-welded heat-affected zone are likely to become coarse, and the strength of the spot-welded joint is low. Therefore, Japanese Patent Laid-Open No. 3-177538, which regulates the amount of oxygen in steel,
JP-A-63-317625 which defines the amount of Ti-Nb-B
JP-A-63-317648, JP-A-63
There is Japanese Patent Application Laid-Open No. 63-317647 and Japanese Patent Application Laid-Open No. 63-317647 which defines the size and amount of Ti precipitates.
【0004】これらの方法は基本的には一旦A3 変態点
以下室温まで冷却されたスラブを再加熱し、熱間圧延す
るといったプロセスを前提とする。これに対して、省エ
ネルギー、省プロセスの観点から、IF鋼において連続
鋳造鋳片をA3 変態点以下に冷却することなく、直送圧
延する方法が開示されている(例えば、特開昭59−1
23721号公報、特開昭62−278232号公
報)。These methods are basically premised on a process of reheating a slab once cooled to room temperature below the A 3 transformation point and hot rolling. On the other hand, from the viewpoint of energy saving and process saving, a method of directly feeding and rolling an IF steel without cooling a continuously cast slab to a temperature not higher than the A 3 transformation point has been disclosed (for example, JP-A-59-1).
23721, and JP-A-62-278232).
【0005】しかし、このような単なる直送圧延材にお
いては、熱間圧延時の表面割れが生じやすく、歩留りが
低下するという問題がある。そこで、IF鋼に限ったも
のではないが、特開昭59−189001号公報、特開
平2−37950号公報、特公平2−18936号公報
は、連続鋳造鋳片の表層部のみを内部より意図的に冷却
し、表面割れ感受性を低減させた直送圧延法を開示して
いる。However, such a mere straight rolled material has a problem that surface cracks are likely to occur during hot rolling and the yield is reduced. Therefore, although not limited to IF steel, JP-A-59-189001, JP-A-2-37950, and JP-B-2-18936 intend only the surface layer portion of a continuously cast slab from the inside. Discloses a direct-rolling method in which the susceptibility to surface cracking is reduced by mechanical cooling.
【0006】[0006]
【発明が解決しようとする課題】しかしながら上記の従
来技術には以下の様な問題点があった。連続鋳造鋳片を
A3 変態点以下室温まで冷却し、再加熱圧延する方法は
省エネルギー、省プロセスの点で問題があり、直送圧延
する方法は、表面割れの問題がある。また、これまでの
連続鋳造鋳片の表層部のみを冷却する方法は、極低炭素
鋼を対象とはしておらず、表面割れ対策のみに焦点が当
てられており、積極的に材質を向上させようとするもの
ではない。However, the above-mentioned prior art has the following problems. The method of cooling the continuously cast slab to room temperature below the A 3 transformation point and reheating and rolling is problematic in terms of energy saving and process saving, and the method of direct feed rolling is problematic in surface cracking. In addition, the method of cooling only the surface layer of continuous cast slabs so far does not target ultra-low carbon steel, but focuses only on surface crack countermeasures, and actively improves the material quality. It's not something you want to do.
【0007】また、Tiの析出物の寸法と量を規定する
方法は、通常の連続鋳造では達成できない鋳造速度を必
要とし、表層部と内部の析出物を別々に制御しようとす
るものではない。そこで、本発明は、従来着目されてい
なかったIF鋼の連続鋳造鋳片の表層部のみを内部より
強冷却し、その後鋳片内部の顕熱により復熱させる方法
を前提として、単なる省エネルギー、省プロセスのみな
らず、組成と連続鋳造鋳片の表層部および内部の温度を
別々に制御することにより、鋼板の特性として、スポッ
ト溶接性と表面性状を積極的に向上させたIF鋼板を提
供することを目的とする。Further, the method of defining the size and amount of Ti precipitates requires a casting speed that cannot be achieved by ordinary continuous casting, and does not attempt to control the surface layer portion and the inside precipitates separately. Therefore, the present invention is based on a method of strongly cooling only the surface layer portion of a continuously cast slab of IF steel, which has not been paid attention in the past, and then recovering heat by sensible heat inside the slab. To provide an IF steel sheet having positively improved spot weldability and surface properties as steel sheet characteristics by controlling not only the process but also the composition and the temperature of the surface layer portion and the internal temperature of the continuously cast slab separately. With the goal.
【0008】[0008]
【課題を解決するための手段】上記課題は以下の手段に
より解決される。 重量%で、C:0.005%以下、N:0.004%以下、M
n:0.03〜2.7%、Si:0.8%以下、P:0.1%以下、S:
0.001〜0.02% 、sol.Al:0.01〜0.08% 、Ti:0.00
5〜0.12% を含有し、前記成分間に下記の関係があるこ
とを特徴とするスポット溶接性と表面性状に優れた鋼
板。 (Ne /14) +(S/32)≧ 0.00023 (Mn+Tie )/S≧ 8 但し、Ne =min((14Ti/48) 、N) Tie =Ti−(48Ne /14) である。The above-mentioned problems can be solved by the following means. % By weight, C: 0.005% or less, N: 0.004% or less, M
n: 0.03 to 2.7%, Si: 0.8% or less, P: 0.1% or less, S:
0.001-0.02%, sol.Al: 0.01-0.08%, Ti: 0.00
A steel sheet containing 5 to 0.12% and having the following relationships among the above components and having excellent spot weldability and surface properties. (N e / 14) + (S / 32) ≧ 0.00023 (Mn + T i e ) / S ≧ 8 where N e = min ((14 Ti / 48), N) T i e = Ti- (48 N e / 14) .
【0009】 に記載の成分に加え、重量%で、
B:0.0002〜0.003%を含有することを特徴とするに記
載のスポット溶接性と表面性状に優れた鋼板。In addition to the ingredients described in,
B: 0.0002 to 0.003% is contained, and the steel sheet excellent in spot weldability and surface properties described in [1].
【0010】 またはに記載の成分に加え、重量
%で、Nb: 0.003〜0.05% を含有することを特徴とす
るまたはに記載のスポット溶接性と表面性状に優れ
た鋼板。In addition to the components described in or, Nb: 0.003 to 0.05% in weight% is contained, and the steel sheet excellent in spot weldability and surface properties described in or.
【0011】 下記の(a)、(b)、(c)の工程
を順次行うことを特徴とするスポット溶接性と表面性状
に優れた鋼板の製造方法。 (a)重量%で、C:0.005%以下、N:0.004%以下、M
n:0.03〜2.7%、Si:0.8%以下、P:0.1%以下、S:
0.001〜0.02% 、sol.Al:0.01〜0.08% 、Ti: 0.0
05〜0.12% を含有し、前記成分間に下記の関係がある鋳
片を連続鋳造する工程と、 (Ne /14) +(S/32)≧ 0.00023 (Mn+Tie )/S≧ 8 但し、Ne =min((14Ti/48) 、N) Tie =Ti−(48Ne /14) である。(b)前記連続
鋳造した鋳片を室温まで冷却することなく、鋳片表面か
ら最小 5mmまで、最大鋳片厚みの20%までを一旦Ar1
以下に冷却し、その後、鋳片内部の顕熱により、もしく
は、短時間の保温もしくは加熱により、再び鋳片表面を
1000〜1150℃の範囲に復熱させる工程と、 (c)前記復熱させた鋳片を直ちに熱間圧延する工程。A method for producing a steel sheet having excellent spot weldability and surface properties, which comprises sequentially performing the following steps (a), (b), and (c). (A)% by weight, C: 0.005% or less, N: 0.004% or less, M
n: 0.03 to 2.7%, Si: 0.8% or less, P: 0.1% or less, S:
0.001-0.02%, sol.Al: 0.01-0.08%, Ti: 0.0
A step of continuously casting a slab containing 05 to 0.12% and having the following relationships among the above components, (N e / 14) + (S / 32) ≧ 0.00023 (Mn + Ti e ) / S ≧ 8 N e = min ((14 Ti / 48), N) T i e = Ti- (48 N e / 14). (B) Without cooling the continuously cast slab to room temperature, once a minimum of 5 mm from the slab surface, up to 20% of the maximum slab thickness is once Ar 1
After cooling to the following, sensible heat inside the slab, or by heat retention or heating for a short time, the surface of the slab again
A step of reheating to a range of 1000 to 1150 ° C., and (c) a step of immediately hot rolling the reheated slab.
【0012】 に記載の成分に加え、重量%で、
B:0.0002〜0.003%を含有することを特徴とするに記
載のスポット溶接性と表面性状に優れた鋼板の製造方
法。In addition to the ingredients described in,
B: 0.0002 to 0.003% is contained, The manufacturing method of the steel plate excellent in the spot weldability and surface quality as described in the above.
【0013】 またはに記載の成分に加え、重量
%で、Nb: 0.003〜0.05% を含有することを特徴とす
るまたはに記載のスポット溶接性と表面性状に優れ
た鋼板の製造方法。The method for producing a steel sheet having excellent spot weldability and surface properties as described in or, further containing Nb: 0.003 to 0.05% in weight% in addition to the components described in or.
【0014】 下記の工程を備えたことを特徴とする
スポット溶接性と表面性状に優れた冷間圧延鋼板の製造
方法。 (a)〜のいずれか一つに記載した工程と、(b)
前記工程により得られた熱延鋼板を、更に冷間圧延する
工程。A method for producing a cold-rolled steel sheet having excellent spot weldability and surface properties, characterized by comprising the following steps. (A) to the step described in any one of, and (b)
A step of further cold rolling the hot rolled steel sheet obtained in the above step.
【0015】[0015]
【作用】本発明の直送圧延プロセスは連続鋳造鋳片、主
にスラブの表層部のみを強制冷却し、主に復熱によりオ
ーステナイト→フェライト、フェライト→オーステナイ
ト変態を繰り返し、組織の微細化を図るとともに、初析
オーステナイト粒界に析出したFe−S系化合物と繰り
返し変態した後のオーステナイト粒界との不一致化によ
り、Fe−S系化合物に起因する熱間圧延割れを防止す
る。また、内部においては、通常の直送圧延と同じく、
冷却−再加熱プロセスを経ずに熱間圧延されるために、
TiN、MnSのみならずTiSが非平衡に析出し微細
分散する。In the direct rolling process of the present invention, only the surface layer portion of the continuously cast slab, mainly the slab, is forcibly cooled and the austenite → ferrite and ferrite → austenite transformations are repeated mainly by recuperation to achieve a finer structure. The hot-rolling cracks caused by the Fe-S-based compound are prevented by making the Fe-S-based compound deposited on the pro-eutectoid austenite grain boundary and the austenite grain boundary after repeated transformation disagree. In addition, inside, as with normal direct rolling,
In order to be hot-rolled without going through the cooling-reheating process,
Not only TiN and MnS but also TiS precipitates non-equilibrium and is finely dispersed.
【0016】このような微細に分散した析出物はスポッ
ト溶接熱影響部の結晶粒粗大化に対して抑制効果を有す
る。このため、本発明による方法においては、省エネル
ギー、省プロセス達成のみならず表面性状およびスポッ
ト溶接性が大幅に向上するわけである。Such finely dispersed precipitates have an effect of suppressing the crystal grain coarsening in the spot welding heat affected zone. Therefore, in the method according to the present invention, not only energy saving and process saving can be achieved but also surface properties and spot weldability are greatly improved.
【0017】以下に、本発明の成分組成の限定理由につ
いて説明する。Cは固溶状態で存在すると、鋼を硬質化
するだけでなく、常温時効劣化を招き、冷間圧延−焼鈍
材においては深絞り性向上に有利な集合組織形成に悪影
響を及ぼすので、極力低下させることが望ましく、その
含有量は0.005%以下とする。The reasons for limiting the component composition of the present invention will be described below. When C is present in a solid solution state, it not only hardens the steel but also causes deterioration at room temperature aging, which adversely affects the formation of a texture in cold rolling-annealing material, which is advantageous for improving deep drawability. It is desirable that the content be 0.005% or less.
【0018】Nは固溶状態で存在するとCと同様の悪影
響を及ぼすので、極力低下させることが望ましく、その
上限を0.004%とする。しかし、微細TiNが存在する場
合はスポット溶接熱影響部の結晶粒粗大化を抑制するの
で、TiとSの関係で後述する量は確保する必要があ
る。Since N has the same adverse effect as C when it exists in a solid solution state, it is desirable to reduce it as much as possible, and its upper limit is made 0.004%. However, when fine TiN is present, grain coarsening of the spot-welded heat-affected zone is suppressed, so it is necessary to secure the amount described below in relation to Ti and S.
【0019】Sは熱間圧延性を低下させ、熱間圧延時の
表面割れの原因となるので、上限を0.02% とする。しか
し、少なすぎるとスケールの剥離性が悪くなると同時
に、スポット溶接熱影響部の結晶粒粗大化抑制に必要な
微細MnSおよびTiSが確保できなくなるので、0.00
1%以上は必要である。したがって、含有量は 0.001〜0.
02% とする。S reduces the hot rolling property and causes surface cracks during hot rolling, so the upper limit is made 0.02%. However, if it is too small, the peelability of the scale deteriorates, and at the same time, it becomes impossible to secure the fine MnS and TiS necessary for suppressing the coarsening of the crystal grains in the heat affected zone of spot welding.
1% or more is necessary. Therefore, the content is 0.001-0.
02%
【0020】MnはSによる熱間脆性を抑制する効果を
有すると同時に、微細なMnSによりスポット溶接熱影
響部の結晶粒粗大化を防ぐことができる。本発明のS量
の範囲に対しては、少なくとも0.03% は添加しなければ
ならない。しかし、多量の添加はIF鋼といえども深絞
り性などの成形性を劣化させるので、上限を2.7%とす
る。Mn has an effect of suppressing hot brittleness due to S, and at the same time, fine MnS can prevent coarsening of crystal grains in the heat-affected zone of spot welding. For the S amount range of the present invention, at least 0.03% must be added. However, addition of a large amount deteriorates formability such as deep drawability even with IF steel, so the upper limit is made 2.7%.
【0021】Siは成形性への悪影響が小さいわりに強
度上昇に寄与する元素であるが、多量の添加は顕著な成
形性の劣化を招くので、上限を0.8%とする。Si is an element that contributes to an increase in strength in spite of its small adverse effect on formability, but addition of a large amount causes remarkable deterioration of formability, so the upper limit is made 0.8%.
【0022】PはSiと同様に成形性への悪影響が小さ
いわりに強度上昇に寄与する元素であるが、多量の添加
は偏析による脆化を招くので、上限を0.1%とする。Similar to Si, P is an element that contributes to the increase in strength in spite of its small adverse effect on formability, but addition of a large amount causes embrittlement due to segregation, so the upper limit is made 0.1%.
【0023】sol.AlはAlとして脱酸および固溶Nの
固定のために添加する必要がある。0.01% 未満ではその
効果が得られず、逆に0.08% より多いと深絞り性など成
形性の劣化を招くと同時に経済性を損ねる原因にもなる
ので、添加量は0.01〜0.08%とする。It is necessary to add sol.Al as Al for deoxidizing and fixing solid solution N. If it is less than 0.01%, the effect cannot be obtained, and conversely, if it is more than 0.08%, it causes deterioration of formability such as deep drawability and at the same time causes a loss of economy, so the addition amount is set to 0.01 to 0.08%.
【0024】TiはTiNを形成し、さらにTiSとし
てSを固定しMnと同様の熱間脆性を抑制し、表面性状
を向上させると同時に、微細析出することにより、スポ
ット溶接熱影響部の結晶粒粗大化を防ぐことができる。
しかしながら、過剰の添加は効果が飽和するだけでな
く、コスト上昇を招くために、添加量は 0.005〜0.12%
とする。Ti forms TiN and further fixes S as TiS to suppress hot embrittlement similar to Mn to improve surface properties and at the same time, finely precipitates the crystal grains in the spot welding heat affected zone. Coarsening can be prevented.
However, excessive addition not only saturates the effect, but also causes cost increase, so the addition amount is 0.005-0.12%.
And
【0025】本発明においては上記組成を基本成分とす
るが、必要に応じて以下の元素を1種または2種以上添
加してもよい。In the present invention, the above composition is used as a basic component, but if necessary, one or more of the following elements may be added.
【0026】Nb、Bはそれぞれ二次加工脆化防止の効
果があるので、何れか一方または両方を添加してもよ
い。それぞれ0.003%、0.0002% 未満だとその効果が小さ
く、逆にそれぞれ0.05% 、0.003%を超えるとその効果が
飽和するだけではなく、コスト上昇を招くことになる。
したがって、添加量はNbとBはそれぞれ 0.003〜0.05
% 、0.0002〜0.003%とする。Since Nb and B each have the effect of preventing secondary processing embrittlement, either one or both may be added. If it is less than 0.003% or 0.0002%, the effect is small, and if it exceeds 0.05% or 0.003%, the effect is not only saturated, but also the cost is increased.
Therefore, the addition amount of Nb and B is 0.003 to 0.05, respectively.
%, 0.0002 to 0.003%.
【0027】その他、V、Cr、Cu、およびNiなど
についてもそれぞれ1%以下、不純物であるSnについて
も0.02% 以下であれば本発明の効果が損なわれることは
ないので、含有してもかまわない。In addition, if V, Cr, Cu, Ni, etc. are each 1% or less and Sn, which is an impurity, is 0.02% or less, the effect of the present invention is not impaired. Absent.
【0028】次に、製造条件と本発明における重要な関
係式である(Ne /14) +(S/32)≧ 0.00023および
(Mn+Tie )/S≧ 8について説明する。但し、N
e =min((14Ti/48) 、N)、Tie =Ti−(48
Ne /14) である。なお、 min((14Ti/48) 、N)
は(14Ti/48) とNの小さい方を意味する。Next, the manufacturing conditions and the important relational expressions in the present invention, (N e / 14) + (S / 32) ≧ 0.00023 and (Mn + Ti e ) / S ≧ 8, will be described. However, N
e = min ((14Ti / 48 ), N), Ti e = Ti- (48
N e / 14). In addition, min ((14Ti / 48), N)
Means the smaller of (14Ti / 48) and N.
【0029】本発明の製造方法においては、連続鋳造後
鋳片を室温まで冷却することなく、鋳片の保有熱を利用
して直送圧延する。通常の冷塊になった鋳片を再加熱す
る方法では、加熱中にTiN、MnSあるいはTiSが
オストワルド成長により粗大化してしまうが、直送圧延
法では、再加熱に比較して鋳片の状態で1000℃以上にさ
らされる時間も極めて短く、それ以下の温度においても
圧延中に板厚が減少していくために、鋳片に比較し冷却
速度が大となる。In the manufacturing method of the present invention, after continuous casting, the slab is directly fed and rolled by utilizing the heat retained by the slab without cooling to room temperature. In the method of reheating a slab that has become a normal cold ingot, TiN, MnS, or TiS is coarsened due to Ostwald growth during heating, but in the direct-feed rolling method, the slab is in a state of slab as compared with reheating. The time of exposure to 1000 ° C or higher is extremely short, and the plate thickness decreases during rolling even at temperatures lower than 1000 ° C, resulting in a higher cooling rate than that of slabs.
【0030】従って、上記析出物の核生成が遅れ、短時
間に一挙に生成するため微細に分散することになり、ス
ポット溶接熱影響部の結晶粒粗大化を抑制するようにな
る。ここで、TiはまずTiNとして析出し、次に残っ
たTiがMnSと競合しながらTiSとして析出する。
このような3種類の微細析出物をどの程度確保すればよ
いかについて検討した結果、(Ne /14) +(S/32)
≧ 0.00023であることが判明した。Therefore, the nucleation of the precipitate is delayed, and the precipitates are generated all at once in a short time, so that they are finely dispersed, and the grain coarsening of the spot-welding heat-affected zone is suppressed. Here, Ti is first deposited as TiN, and then the remaining Ti is deposited as TiS while competing with MnS.
As a result of examining how much such three kinds of fine precipitates should be secured, (N e / 14) + (S / 32)
It was found that ≧ 0.00023.
【0031】図4は、(Ne /14) +(S/32)とスポ
ット溶接継手強度との関係を示す図である。Ne はTi
NとしてのN量を意味し、本発明の請求範囲ではSはす
べてMnSあるいはTiSとなることから、(Ne /1
4) +(S/32)は原子量比に置き換えたTiN、Ti
SおよびMnSの総量を表し、図4に示すように、この
値を0.00023 以上に制御すればスポット溶接熱影響部の
結晶粒粗大化を抑制でき、溶接強度の向上が達成でき
る。FIG. 4 is a graph showing the relationship between (N e / 14) + (S / 32) and the spot-welded joint strength. N e is Ti
It means the amount of N as N, and since all S is MnS or TiS in the claims of the present invention, (N e / 1
4) + (S / 32) is the atomic weight ratio of TiN and Ti
It represents the total amount of S and MnS, and as shown in FIG. 4, if this value is controlled to be 0.00023 or more, coarsening of crystal grains in the spot-welded heat-affected zone can be suppressed and improvement in welding strength can be achieved.
【0032】一方、鋳片の表層部に関しては、熱間圧延
される通常の直送圧延においては、A3 変態点以下冷却
されることがないため、粗大なオーステナイト粒界に析
出する低融点FeSあるいはFe含有量の高い(Fe、
Mn)Sが熱間圧延時の粒界割れの原因となり、熱間圧
延板のみならず、冷間圧延板およびめっき処理鋼板の表
面性状を劣化させる。したがって、表面と内質特性の同
時向上は従来の技術では決して成り立たないというのが
現状である。On the other hand, the surface layer portion of the cast slab is not cooled below the A 3 transformation point in ordinary direct rolling which is hot-rolled, so that the low melting point FeS or the precipitation of coarse austenite grain boundaries is obtained. High Fe content (Fe,
Mn) S causes intergranular cracking during hot rolling and deteriorates the surface properties of not only the hot rolled plate but also the cold rolled plate and the plated steel plate. Therefore, the current situation is that the simultaneous improvement of surface and internal properties cannot be established by the conventional techniques.
【0033】そこで本発明においては、表層部のみをA
r1 変態点(具体的には、約 890−1335C0.5 (℃) )
以下にまで強制的に冷却し、鋳片内部の顕熱により再び
表面を1000℃以上1150℃以下に復熱させる。ただし、表
面が1000℃以上に復熱しないと、熱間圧延仕上がり温度
が低下し、通板性が悪くなるだけでなく、板厚変動が大
きくなり表面性状が低下することになる。Therefore, in the present invention, only the surface layer is A
r 1 transformation point (specifically, about 890-1335C 0.5 (℃))
It is forcibly cooled to the temperature below, and the surface is reheated to 1000 ° C or more and 1150 ° C or less by sensible heat inside the slab. However, if the surface is not reheated to 1000 ° C. or higher, not only the finish temperature of hot rolling is lowered and the stripability is deteriorated, but also the variation in strip thickness is increased and the surface quality is degraded.
【0034】しかし、復熱温度が1150℃を超えると、主
として硫化物が再固溶し熱間圧延中に動的析出すること
になり、熱延鋼板の表面割れが顕在化し、上記復熱法の
効果が失われることになる。したがって、適正な復熱温
度範囲は1000〜1150℃である。この温度以下に冷却され
復熱した領域はオーステナイト→フェライトおよびフェ
ライト→オーステナイト変態の繰り返しにより、組織が
微細なものとなるだけでなく、旧オーステナイト粒界の
(Fe、Mn)S系介在物の析出位置が熱間圧延時の粒
界とは異なってくるために、粒界強度が格段に高まり、
各段階での薄鋼板製品の表面性状が向上する。However, when the recuperation temperature exceeds 1150 ° C., mainly sulfides are solid-resolved and dynamically precipitate during the hot rolling, and surface cracks of the hot rolled steel sheet become apparent, and the above recuperation method is used. The effect of will be lost. Therefore, the proper recuperation temperature range is 1000 to 1150 ° C. The region which has been cooled and reheated below this temperature not only has a fine structure due to repeated austenite → ferrite and ferrite → austenite transformations, but also precipitates (Fe, Mn) S-based inclusions in the former austenite grain boundaries. Since the position is different from the grain boundary during hot rolling, the grain boundary strength is significantly increased,
The surface quality of the thin steel sheet product at each stage is improved.
【0035】ただし、(Mn+Tie )/S≧8を満足
できないと非平衡的にフリーのSが新たな微細オーステ
ナイト粒界に偏析し熱間延性を低下させるので、復熱と
(Mn+Tie )/S≧8の組み合わせが必須である。
図3は、(Mn+Tie )/Sと熱延板表面疵発生率の
関係を示す図である。ここで、Tie はTiNになった
残りのTiSになりうるTi量を意味し、硫化物になり
うるMnとTie の和がSに対して8倍であれば、図3
に示すように、熱間脆性による表面疵発生を回避できる
わけである。However, if (Mn + Ti e ) / S ≧ 8 is not satisfied, free S is segregated non-equilibrium to new fine austenite grain boundaries to lower the hot ductility, so that reheat and (Mn + Ti e ) / A combination of S ≧ 8 is essential.
Figure 3 is a diagram showing the relationship (Mn + Ti e) / S and the hot rolled sheet surface flaw generation rate. Here, Ti e denotes the amount of Ti can be a remaining TiS became TiN, if 8 times the sum of Mn and Ti e which can be a sulfide S, 3
As shown in, the occurrence of surface defects due to hot brittleness can be avoided.
【0036】原子量比からはTiとMnは等価ではない
が、Tiのほうが拡散速度が大きいために、結果的には
TiとMnの効果は同じとなる。強制冷却部における上
記析出物は、冷却段階で核生成しているために復熱段階
で中心部に比較して粗大化が進む。これは、熱間脆性を
抑制する点からは望ましいが、スポット溶接熱影響部の
結晶粒粗大化抑制に関してはその効果を失うことにな
る。Although Ti and Mn are not equivalent from the atomic weight ratio, Ti and Mn have the same effect as a result because Ti has a higher diffusion rate. Since the precipitates in the forced cooling section have nucleated in the cooling stage, they become coarser in the recuperating stage than in the central portion. This is desirable from the viewpoint of suppressing hot embrittlement, but it loses its effect on suppressing crystal grain coarsening in the spot welding heat affected zone.
【0037】ここで、図1は片側当たりのAr1 以下に
冷却された表層部深さと熱延板表面疵発生率の関係を示
す図、図2は片側当たりのAr1 以下に冷却された表層
部範囲とスポット溶接継手強度との関係を示す図であ
る。表面性状の観点からはAr 1 以下に強制冷却される
表層部が図1に示すように、鋳片がスラブの場合は広幅
表面の片側あたり、表面から最小 5mm以上必要であるの
に対して、逆にスポット溶接性の観点からはAr1 変態
点以下に強制冷却される表層部が図2に示すように、広
幅表面の片側あたり最大全厚の20%以下でないと、表層
部の粗大TiN、TiSおよびMnSの影響が無視でき
なくなる。なお、角形鋳片の場合は、4表面から最小 5
mm、最大全厚の20%である。そこで、Ar1 以下に強制
冷却される表層部は片側あたり少なくとも5mm以上で、
かつ、最大全厚の20%以下とする。Here, FIG. 1 shows Ar per side.1less than
Shows the relationship between the depth of the cooled surface layer and the surface defect rate of hot-rolled sheet.
Fig. 2 shows Ar per side1Surface layer cooled below
It is a diagram showing the relationship between the area range and spot welded joint strength.
It Ar from the viewpoint of surface texture 1Is forced to
As shown in Fig. 1, the surface layer is wide when the slab is a slab.
A minimum of 5 mm from the surface is required on each side of the surface
On the contrary, from the viewpoint of spot weldability, Ar1transformation
As shown in Fig. 2, the surface layer that is forcibly cooled below the point is wide.
The surface layer must be 20% or less of the maximum total thickness per side of the width surface.
The effect of coarse TiN, TiS and MnS on the
Disappear. In the case of square slab, a minimum of 5 from 4 surfaces
mm, 20% of maximum total thickness. So Ar1Forced to
The surface layer to be cooled should be at least 5 mm or more per side,
And, it shall be 20% or less of the maximum total thickness.
【0038】このような成分組成のみならず強制冷却お
よび復熱温度ならびに表層部深さの限定は本発明の骨子
をなすものである。The limitation of the forced cooling and recuperating temperature and the depth of the surface layer part as well as the composition of components as described above are the main feature of the present invention.
【0039】復熱した鋳片についてはそのまま熱間圧延
してもかまわないし、圧延スケジュールの調整およびス
ラブエッジ部の温度低下補償などの理由により、鋳片表
面が1000℃以上1150℃を超えない範囲で短時間の全体ま
たは局部の加熱・保熱をしてもかまわない。なお、加熱
時間については特に規定しないが、析出物の粗大化また
は再固溶を抑制するためには15min 以内が望ましい。The reheated slab may be hot-rolled as it is, and the slab surface does not exceed 1000 ° C. and 1150 ° C. for reasons such as adjusting the rolling schedule and compensating for temperature decrease at the slab edge. You may heat / heat the whole or local area for a short time. The heating time is not particularly specified, but it is preferably within 15 min in order to prevent coarsening or re-dissolution of precipitates.
【0040】従って、本発明においては、連続鋳造する
に当たり、連続鋳造鋳片の表層部のみをAr1 変態点以
下に強制冷却し、鋳片内部の顕熱を利用し、表面を再び
1000℃以上1150℃以下に復熱させ、加熱せずに、あるい
は短時間の加熱・保熱により熱間圧延することとする。
このような復熱は、連続鋳造スラブの2次冷却パターン
を初期強冷−後期弱冷とすることにより達成できる。な
お、表面からどの程度までAr1 以下に強制冷却したか
については、熱・冷却計算からも把握することができる
し、復熱後の鋳片の断面組織の変化からも確認すること
ができる。Therefore, in the present invention, in continuous casting, only the surface layer portion of the continuously cast slab is forcibly cooled to below the Ar 1 transformation point and the sensible heat inside the slab is utilized to resurface the surface.
Reheat to 1000 ° C or more and 1150 ° C or less and perform hot rolling without heating or by heating / holding heat for a short time.
Such recuperation can be achieved by changing the secondary cooling pattern of the continuous casting slab from early strong cooling to late weak cooling. The extent to which the surface is forcibly cooled to below Ar 1 can be understood from the heat / cooling calculation, and can also be confirmed from the change in the cross-sectional structure of the slab after reheat.
【0041】また、熱間圧延以降のプロセスについては
特に規定しないが、本発明の効果は熱延鋼板、冷延鋼板
および表面処理鋼板のいずれにおいても得られる。基本
的なプロセスとしては、例えば、熱延鋼板の場合は熱間
圧延−巻取処理−スケール除去があり、冷延鋼板の場合
はさらに冷間圧延−連続焼鈍またはバッチ焼鈍−調質圧
延があり、表面処理鋼板の場合は熱延板のスケール除去
後、冷間圧延後あるいは焼鈍後に、調質圧延や一段また
は多段の溶融または電気めっきおよびその組み合わせに
よりめっき処理が施されるといった方法が一般的プロセ
スである。この他、レベリング、中間焼鈍、研削、エッ
ジ切断などのプロセスが付加されてもなんら問題はな
い。Although the process after hot rolling is not particularly specified, the effect of the present invention can be obtained in any of hot rolled steel sheet, cold rolled steel sheet and surface treated steel sheet. As a basic process, for example, in the case of a hot rolled steel sheet, there is hot rolling-winding treatment-scale removal, and in the case of a cold rolled steel sheet, there is further cold rolling-continuous annealing or batch annealing-temper rolling. In the case of surface-treated steel sheets, after the scale of the hot-rolled sheet is removed, after cold rolling or after annealing, a method such as temper rolling, one-step or multi-step melting or electroplating and a combination thereof is generally used. Is a process. In addition, there is no problem even if processes such as leveling, intermediate annealing, grinding, and edge cutting are added.
【0042】[0042]
【実施例】表1は本発明鋼の組成を示す表であり、表2
は比較鋼の組成を示す表である。また表3は本発明鋼の
復熱直送圧延条件ならびに特性を示す表であり、表4は
比較鋼の復熱直送圧延条件ならびに特性を示す表であ
る。EXAMPLES Table 1 is a table showing the composition of the steel of the present invention, and Table 2
Is a table showing the composition of comparative steels. Further, Table 3 is a table showing the recuperative heat direct rolling conditions and characteristics of the steel of the present invention, and Table 4 is a table showing the reheat direct heat rolling conditions and characteristics of the comparative steel.
【0043】[0043]
【表1】 [Table 1]
【0044】[0044]
【表2】 [Table 2]
【0045】[0045]
【表3】 [Table 3]
【0046】[0046]
【表4】 [Table 4]
【0047】ここで、比較鋼の一部については鋳片を室
温まで冷却し、再加熱したもの(鋼17−h)、表層部を
Ar1 変態点以下に強制冷却しない通常の直送圧延材
(鋼17−i)も含む。熱間圧延については厚み 220およ
び250mm の鋳片を 880〜910 ℃仕上げで 2.4〜4.5mm と
し、ランナウトテーブル上で冷却後、 600〜680 ℃で巻
き取った。Here, for some of the comparative steels, the slab was cooled to room temperature and reheated (steel 17-h), and a normal straight-rolled material in which the surface layer portion was not forcedly cooled to below the Ar 1 transformation point ( Including steel 17-i). For hot rolling, slabs of 220 and 250 mm in thickness were finished at 880 to 910 ℃ to 2.4 to 4.5 mm, cooled on a runout table, and then wound at 600 to 680 ℃.
【0048】冷延鋼板はさらに酸化スケール除去後、冷
間圧延により、 0.7〜1.4mm とした後、 800〜880 ℃で
連続焼鈍を行い、さらに焼鈍後 0.5%調質圧延を行っ
た。なお、鋼20−aについては連続焼鈍の代わりに 750
℃で箱焼鈍を行った。溶融亜鉛めっき材(鋼2−a)に
ついては、冷間圧延後、 820℃焼鈍し、 460℃まで冷却
した段階で片面あたり60g/m2の溶融亜鉛をめっきし、引
続き 500℃で合金化処理を行った。その後、 1.0%の調
質圧延後、さらに片面あたり 3g/m2の80%Fe−Zn合
金の上層電気めっきを施した。有機被覆鋼板(鋼8−
a)については、調質圧延後、88%Zn−Ni合金電気
めっきを30g/m2、クロメート層を50mg/m2 、樹脂層1μ
m の複合被覆を行った。The cold-rolled steel sheet was further subjected to cold rolling after removing the oxide scale to 0.7 to 1.4 mm, continuous annealing at 800 to 880 ° C., and further 0.5% temper rolling after annealing. For steel 20-a, instead of continuous annealing, 750
Box annealing was performed at ℃. Hot-dip galvanized material (Steel 2-a) is cold-rolled, annealed at 820 ° C, and when it is cooled to 460 ° C, 60 g / m 2 of hot-dip galvanizing is plated on one side, and then alloying is performed at 500 ° C. I went. Then, after 1.0% temper rolling, upper layer electroplating of 80% Fe-Zn alloy with 3 g / m 2 per side was further applied. Organic coated steel sheet (Steel 8-
For a), after temper rolling, 88% Zn-Ni alloy electroplating 30 g / m 2 , chromate layer 50 mg / m 2 , resin layer 1 μm.
A m 2 composite coating was applied.
【0049】このような薄鋼板の引張特性をJIS5号試験
片により評価するとともに、スポット溶接性については
JIS Z3136 に準拠して引張せん断試験を実施した。引張
せん断強度は板厚が厚いほど、また母材強度が高いほど
高い値となる。そこで、得られた引張せん断強度が十分
な値か否かを評価するために、従来データを重回帰する
ことにより得られた計算値{356.7 ・t1.42 ・(TS/9.8)
0.84}と実測値を比較した。したがって、実測値と計算
値の比である引張せん断強度比が1に近い値であればス
ポット溶接性に優れるものと判断した。ただし、t:板
厚(mm)、TS:引張強度(MPa) である。The tensile properties of such a thin steel sheet were evaluated by JIS No. 5 test pieces, and the spot weldability was
A tensile shear test was carried out in accordance with JIS Z3136. The tensile shear strength becomes higher as the plate thickness becomes thicker and as the base metal strength becomes higher. Therefore, in order to evaluate whether the obtained tensile shear strength is a sufficient value, the calculated value obtained by multiple regression of the conventional data {356.7 ・ t 1.42・ (TS / 9.8)
0.84 } and the measured value were compared. Therefore, if the tensile shear strength ratio, which is the ratio of the actually measured value and the calculated value, is close to 1, it was judged that the spot weldability was excellent. However, t: plate thickness (mm), TS: tensile strength (MPa).
【0050】また、スポット溶接条件は以下の通りであ
る。 電極:CR型(元径16mm、頂角120 °) 電極先端径:6・t0.5mm 電極加圧力:3330・tN 通電時間:12・tサイクル/60Hz 保持時間:60サイクル/60Hz 溶接電流:チリ限界電流 表面性状については熱延鋼板1m2当たりの 5mm以上の疵
個数(視野面積50〜60m2 )により評価した。The spot welding conditions are as follows. Electrode: CR type (Original diameter: 16 mm, Vertical angle: 120 °) Electrode tip diameter: 6 ・ t 0.5 mm Electrode pressure: 3330 ・ tN Energization time: 12 ・ t cycle / 60Hz Holding time: 60 cycles / 60Hz Welding current: Chile Limiting current The surface texture was evaluated by the number of flaws of 5 mm or more per 1 m 2 of hot-rolled steel sheet (viewing area 50 to 60 m 2 ).
【0051】発明鋼はいずれもスポット溶接性および表
面性状に優れるのに対して、Ar1以下に強制冷却され
た表層部が浅い鋼6−d、17−d、19−d、通常直送圧
延材の鋼17−i、復熱温度が低すぎる17−f、復熱温度
が高すぎる17−g、および、(Mn+Tie )/S≧8
を満足していない鋼21−a、22−a、23−a、24−a、
はいずれも表面疵が多く発生している。逆に、Ar1 以
下に強制冷却された表層部が深い鋼6−e 、17−e 、19
−e 、および室温まで冷却−再加熱した鋼17−h、(N
e /14)+(S/32) ≧0.00023 を満足していない鋼25
−a、26−a、27−a、28−aはスポット溶接性に劣
る。All of the invention steels are excellent in spot weldability and surface properties, whereas steels 6-d, 17-d, 19-d, which are forcibly cooled to Ar 1 or less and have a shallow surface layer, are usually straight rolled materials. Steel 17-i, reheat temperature is too low 17-f, reheat temperature is too high 17-g, and (Mn + Ti e ) / S ≧ 8
21-a, 22-a, 23-a, 24-a, which do not satisfy
In each case, many surface defects occur. On the contrary, steels 6-e, 17-e, 19 with deep surface layer that are forcibly cooled to Ar 1 or less
-E, and cooled to room temperature-reheated steel 17-h, (N
Steel that does not satisfy e / 14) + (S / 32) ≧ 0.00023 25
-A, 26-a, 27-a and 28-a are inferior in spot weldability.
【0052】[0052]
【発明の効果】本発明による鋼板およびその製造方法
は、自動車用など良好なスポット溶接性が要求される用
途に対し好適な鋼板、即ち、熱間圧延板、その表面処理
鋼板、冷延鋼板、及びその表面処理鋼板を提供し、産業
上の利用価値が著しく大きい発明である。The steel sheet and the method for producing the same according to the present invention are steel sheets suitable for applications requiring good spot weldability such as automobiles, that is, hot-rolled sheets, surface-treated steel sheets, cold-rolled steel sheets, And a surface-treated steel sheet thereof, which is an invention having a great industrial utility value.
【図1】片側当たりのAr1 以下に冷却された表層部深
さと熱延板表面疵発生率の関係を示す図。FIG. 1 is a diagram showing the relationship between the depth of the surface layer portion cooled to Ar 1 or less per one side and the occurrence rate of surface defects on hot-rolled sheet.
【図2】片側当たりのAr1 以下に冷却された表層部範
囲とスポット溶接継手強度との関係を示す図。FIG. 2 is a diagram showing a relationship between a surface layer range cooled to Ar 1 or less per one side and spot welded joint strength.
【図3】(Mn+Tie )/Sと熱延板表面疵発生率の
関係を示す図。FIG. 3 is a diagram showing the relationship between (Mn + Ti e ) / S and the occurrence rate of surface defects on hot-rolled sheet.
【図4】(Ne /14) +(S/32)とスポット溶接継手
強度との関係を示す図。FIG. 4 is a diagram showing a relationship between (N e / 14) + (S / 32) and spot-welded joint strength.
───────────────────────────────────────────────────── フロントページの続き (72)発明者 吉岡 敬二 東京都千代田区丸の内一丁目1番2号 日 本鋼管株式会社内 (72)発明者 沖本 一生 東京都千代田区丸の内一丁目1番2号 日 本鋼管株式会社内 (72)発明者 出石 智也 東京都千代田区丸の内一丁目1番2号 日 本鋼管株式会社内 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Keiji Yoshioka, Marunouchi 1-2-2, Chiyoda-ku, Tokyo Japan Steel Pipe Co., Ltd. (72) Issei Okimoto 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Inside the Steel Pipe Corporation (72) Inventor Tomoya Izushi 1-2-2 Marunouchi, Chiyoda-ku, Tokyo Inside Nihon Steel Pipe Corporation
Claims (7)
以下、Mn:0.03〜2.7%、Si:0.8%以下、P:0.1%以
下、S: 0.001〜0.02% 、sol.Al:0.01〜0.08% 、T
i: 0.005〜0.12% を含有し、前記成分間に下記の関係
があることを特徴とするスポット溶接性と表面性状に優
れた鋼板。 (Ne /14) +(S/32)≧ 0.00023 (Mn+Tie )/S≧ 8 但し、Ne =min((14Ti/48) 、N) Tie =Ti−(48Ne /14) である。1. C: 0.005% or less, N: 0.004% by weight
Below, Mn: 0.03 to 2.7%, Si: 0.8% or less, P: 0.1% or less, S: 0.001 to 0.02%, sol.Al: 0.01 to 0.08%, T
i: A steel sheet containing 0.005 to 0.12% and having the following relationships among the above components and having excellent spot weldability and surface properties. (N e / 14) + (S / 32) ≧ 0.00023 (Mn + T i e ) / S ≧ 8 where N e = min ((14 Ti / 48), N) T i e = Ti- (48 N e / 14) .
で、B:0.0002〜0.003%を含有することを特徴とする請
求項1に記載のスポット溶接性と表面性状に優れた鋼
板。2. In addition to the components of claim 1, weight%
B: 0.0002 to 0.003% is contained, and the steel plate excellent in spot weldability and surface properties according to claim 1.
加え、重量%で、Nb: 0.003〜0.05% を含有すること
を特徴とする請求項1または請求項2に記載のスポット
溶接性と表面性状に優れた鋼板。3. The spot weldability according to claim 1 or 2, characterized in that, in addition to the components according to claim 1 or claim 2, it contains Nb in an amount of 0.003 to 0.05% by weight. And a steel plate with excellent surface properties.
順次行うことを特徴とするスポット溶接性と表面性状に
優れた鋼板の製造方法。 (a)重量%で、C:0.005%以下、N:0.004%以下、M
n:0.03〜2.7%、Si:0.8%以下、P:0.1%以下、S:
0.001〜0.02% 、sol.Al:0.01〜0.08% 、Ti: 0.0
05〜0.12% を含有し、前記成分間に下記の関係がある鋳
片を連続鋳造する工程と、 (Ne /14) +(S/32)≧ 0.00023 (Mn+Tie )/S≧ 8 但し、Ne =min((14Ti/48) 、N) Tie =Ti−(48Ne /14) である。 (b)前記連続鋳造した鋳片を室温まで冷却することな
く、鋳片表面から最小 5mmまで、最大鋳片厚みの20%ま
でを一旦Ar1 以下に冷却し、その後、鋳片内部の顕熱
により、もしくは、短時間の保温もしくは加熱により、
再び鋳片表面を1000〜1150℃の範囲に復熱させる工程
と、 (c)前記復熱させた鋳片を直ちに熱間圧延する工程。4. A method for producing a steel sheet having excellent spot weldability and surface properties, which comprises sequentially performing the following steps (a), (b) and (c). (A)% by weight, C: 0.005% or less, N: 0.004% or less, M
n: 0.03 to 2.7%, Si: 0.8% or less, P: 0.1% or less, S:
0.001-0.02%, sol.Al: 0.01-0.08%, Ti: 0.0
A step of continuously casting a slab containing 05 to 0.12% and having the following relationships among the above components, (N e / 14) + (S / 32) ≧ 0.00023 (Mn + Ti e ) / S ≧ 8 N e = min ((14 Ti / 48), N) T i e = Ti- (48 N e / 14). (B) Without cooling the continuously cast slab to room temperature, once cool the surface of the slab to a minimum of 5 mm and up to 20% of the maximum slab thickness to Ar 1 or less, and then sensible heat inside the slab. Or by heat retention or heating for a short time,
A step of reheating the surface of the slab again to a range of 1000 to 1150 ° C., and (c) a step of immediately hot rolling the reheated slab.
で、B:0.0002〜0.003%を含有することを特徴とする請
求項4に記載のスポット溶接性と表面性状に優れた鋼板
の製造方法。5. In addition to the components according to claim 4, weight%
B: 0.0002-0.003% is contained, The manufacturing method of the steel plate excellent in the spot weldability and surface quality of Claim 4 characterized by the above-mentioned.
加え、重量%で、Nb: 0.003〜0.05% を含有すること
を特徴とする請求項4または請求項5に記載のスポット
溶接性と表面性状に優れた鋼板の製造方法。6. The spot weldability according to claim 4 or 5, characterized in that, in addition to the components according to claim 4 or 5, it contains Nb: 0.003 to 0.05% by weight. And a method for manufacturing a steel sheet having excellent surface properties.
ポット溶接性と表面性状に優れた冷間圧延鋼板の製造方
法。 (a)請求項4〜6のいずれか一つに記載した工程と、
(b)前記工程により得られた熱延鋼板を、更に冷間圧
延する工程。7. A method for producing a cold-rolled steel sheet having excellent spot weldability and surface properties, comprising the following steps. (A) a step according to any one of claims 4 to 6,
(B) A step of further cold rolling the hot-rolled steel sheet obtained in the above step.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP17854294A JP3240843B2 (en) | 1993-09-24 | 1994-07-29 | Steel plate excellent in spot weldability and surface properties and method for producing the same |
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP25892793 | 1993-09-24 | ||
JP5-258927 | 1993-09-24 | ||
JP17854294A JP3240843B2 (en) | 1993-09-24 | 1994-07-29 | Steel plate excellent in spot weldability and surface properties and method for producing the same |
Publications (2)
Publication Number | Publication Date |
---|---|
JPH07138699A true JPH07138699A (en) | 1995-05-30 |
JP3240843B2 JP3240843B2 (en) | 2001-12-25 |
Family
ID=26498696
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP17854294A Expired - Fee Related JP3240843B2 (en) | 1993-09-24 | 1994-07-29 | Steel plate excellent in spot weldability and surface properties and method for producing the same |
Country Status (1)
Country | Link |
---|---|
JP (1) | JP3240843B2 (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2013234381A (en) * | 2012-04-13 | 2013-11-21 | Kobe Steel Ltd | Thick steel plate with excellent cryogenic toughness |
-
1994
- 1994-07-29 JP JP17854294A patent/JP3240843B2/en not_active Expired - Fee Related
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2013234381A (en) * | 2012-04-13 | 2013-11-21 | Kobe Steel Ltd | Thick steel plate with excellent cryogenic toughness |
Also Published As
Publication number | Publication date |
---|---|
JP3240843B2 (en) | 2001-12-25 |
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