JPH10226843A - Thin steel sheet small in defect and excellent in press formability and its production - Google Patents
Thin steel sheet small in defect and excellent in press formability and its productionInfo
- Publication number
- JPH10226843A JPH10226843A JP3514897A JP3514897A JPH10226843A JP H10226843 A JPH10226843 A JP H10226843A JP 3514897 A JP3514897 A JP 3514897A JP 3514897 A JP3514897 A JP 3514897A JP H10226843 A JPH10226843 A JP H10226843A
- Authority
- JP
- Japan
- Prior art keywords
- steel
- less
- alumina
- press formability
- steel sheet
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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- Heat Treatment Of Sheet Steel (AREA)
- Treatment Of Steel In Its Molten State (AREA)
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明方法は、欠陥が少なく
プレス成形性に優れた薄鋼板およびその製造方法に関す
るものである。詳しくは、表面欠陥およびプレス時の割
れなどの欠陥の発生が少なく、かつ成形性に優れた鋼板
及びその製造方法に関するものであり、自動車および家
電製品の部品などプレス成形に供される鋼板として好適
な薄鋼板およびその製造方法に関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin steel sheet having few defects and excellent press formability, and a method for producing the same. More specifically, the present invention relates to a steel sheet having less surface defects and defects such as cracks during pressing and excellent in formability and a method for producing the same, and is suitable as a steel sheet to be subjected to press forming such as parts of automobiles and home electric appliances. And a method for manufacturing the same.
【０００２】[0002]
【従来の技術】通常自動車、家電製品などに用いられる
鋼板は転炉で溶製された未脱酸の溶鋼をＡｌで脱酸を行
うＡｌキルド鋼で製造されている。このようなＡｌ脱酸
鋼では、脱酸時に添加したＡｌと溶鋼中の酸素が反応し
たり、脱酸後に鋼中に残留したＡｌがスラグや空気中等
の酸素によって酸化してアルミナが生じる。このアルミ
ナは固いので圧延や加工等で破砕されずに鋼板に塊状で
残存し、鋼板の表面に存在する場合は表面疵となって表
面性状を損ない、また、鋼板内部に存在するとプレス成
形時に割れや疵などの欠陥の発生原因となる。そこでこ
れらのアルミナに対してスラグ中や雰囲気中の酸素の制
御による溶鋼中のＡｌの酸化によるアルミナの生成防止
や、溶鋼中へのガスやフラックスの吹き込みによる溶鋼
中のアルミナの浮上促進による低減と、溶鋼中へのＣａ
の添加によってアルミナを圧延・加工時に破砕されやす
いカルシウムアルミネートへ形態制御することによる無
害化が行われてきた。2. Description of the Related Art Steel sheets usually used for automobiles, home electric appliances and the like are made of Al-killed steel which deoxidizes undeoxidized molten steel produced in a converter with Al. In such Al deoxidized steel, Al added at the time of deoxidation reacts with oxygen in the molten steel, or Al remaining in the steel after deoxidation is oxidized by slag, air or other oxygen to produce alumina. Since this alumina is hard, it remains on the steel sheet in a lump without being crushed by rolling or processing, etc.If it exists on the surface of the steel sheet, it becomes a surface flaw and impairs the surface properties. It causes defects such as defects and flaws. Therefore, by controlling oxygen in the slag and atmosphere in these slags, it is possible to prevent the generation of alumina by oxidizing Al in the molten steel, and to reduce the alumina by promoting the floating of the molten steel by blowing gas and flux into the molten steel. , Ca in molten steel
Detoxification has been carried out by controlling the form of alumina into calcium aluminate which is easily crushed at the time of rolling and processing by the addition of iron.
【０００３】しかし、Ａｌで脱酸を行っている限りはア
ルミナ単体の生成は皆無にはできず、除去も不十分であ
る。また、Ｃａ添加による方法もＣａは高価であるとと
もに歩留まりがきわめて悪いために合金コストが高くな
り、また介在物にアルミナを含有するので冷却時に介在
物中に固いアルミナが部分的に晶出し、圧延等によって
も破砕されずに残り欠陥が発生する。さらに、Ｃａを添
加して生成するカルシウムアルミネートは肥大化しやす
く、このような介在物が浮上しきれず残留した場合には
大きな欠陥となる。これらの問題を解決するためにはＡ
ｌ以外の元素で脱酸することが考えられ、特公昭４８−
２９００５号公報に見られるようにＡｌもＳｉも全く添
加せずにＴｉのみで脱酸する方法があるが、この場合Ｍ
ｎのみによる脱酸のためにＴｉ添加前の溶鋼中酸素は非
常に高い値となり、この様な溶鋼にＴｉを添加すると粒
径の大きなチタン酸化物が多量に生成して溶鋼中に残存
し、これはアルミナと同様に固く破砕されにくいので欠
陥となる。そこで、特公平２−９６４６号公報に見られ
るようにＴｉ添加前にＡｌを添加して予備脱酸を行い、
溶鋼酸素を低減した後にＴｉを添加する方法がある。[0003] However, as long as deoxidation is performed with Al, the production of alumina alone cannot be eliminated, and the removal of alumina alone is insufficient. In addition, the method using Ca is expensive, and the alloy cost is high because the yield is extremely low. In addition, since alumina is contained in the inclusions, hard alumina is partially crystallized in the inclusions during cooling, and rolling is performed. Also, the remaining defects are generated without being crushed. Furthermore, calcium aluminate generated by adding Ca tends to be enlarged, and if such inclusions cannot be completely floated and remain, they will be a large defect. To solve these problems, A
It is thought that deoxidation may occur with elements other than l.
As disclosed in Japanese Patent No. 29005, there is a method of deoxidizing only with Ti without adding any Al or Si.
Oxygen in molten steel before Ti addition becomes very high due to deoxidation due to n alone, and when Ti is added to such molten steel, a large amount of titanium oxide having a large grain size is generated and remains in the molten steel, This is a defect because it is hard and not easily crushed like alumina. Therefore, as shown in Japanese Patent Publication No. 2-9646, Al is added before Ti is added to perform preliminary deoxidation,
There is a method of adding Ti after reducing molten steel oxygen.
【０００４】[0004]
【発明が解決しようとする課題】上記方法では溶鋼中の
酸素が高い状態でＡｌを添加するために、Ａｌを多量に
添加する必要があるので多量のアルミナが生成してその
まま残留する。また、ＡｌはＴｉより酸化力が強いため
にＴｉを添加した際にアルミナは還元されずにアルミナ
濃度が高い介在物となるために圧延等によっても破砕さ
れずに残存するので、プレス時に欠陥が発生し易い。ま
た、Ａｌは脱酸力が強いので酸素のコントロールが不安
定である。一方、生成したチタン酸化物の大部分は粒径
が大きくかつ、破砕されにくいチタン酸化物となって溶
鋼中に存在し、その一部は浮上しきれずに残留して欠陥
となりやすい。このように通常の製造方法では、鋼中に
１００μｍ程度の大きさの介在物が含まれるのが一般的
であり、この介在物はプレス成形時に亀裂の起点となる
ので、この種の介在物が多量に含まれるとプレス割れな
どの欠陥が多発するという欠点を有していた。In the above method, since Al is added in a state where oxygen in molten steel is high, a large amount of Al needs to be added, so that a large amount of alumina is generated and remains as it is. In addition, since Al has a stronger oxidizing power than Ti, alumina is not reduced when Ti is added and becomes an inclusion having a high alumina concentration, and remains without being crushed even by rolling or the like. Easy to occur. In addition, since Al has a strong deoxidizing power, control of oxygen is unstable. On the other hand, most of the generated titanium oxide is a titanium oxide having a large particle size and is hard to be crushed and exists in the molten steel, and a part of the titanium oxide is not completely lifted but remains and easily becomes a defect. As described above, in the ordinary manufacturing method, it is common that steel includes inclusions having a size of about 100 μm, and this inclusion becomes a starting point of a crack during press forming. When contained in a large amount, there is a defect that defects such as press cracks occur frequently.
【０００５】また、鋼中に酸可溶Ａｌを多く含有する鋼
は再結晶温度が高くなり、特に極低炭素鋼にＴｉ、Ｎｂ
などの炭窒化物形成元素を添加したＩＦ鋼では、微細な
炭窒化物が鋼中に存在するので、一般の低炭素Ａｌキル
ド鋼よりもさらに高い温度で焼鈍をしなければならなか
った。これを解消する方法として、特開昭６２−３０８
２２号公報のようにＡｌで脱酸を行うものの、脱酸に使
われた以外の余剰Ａｌすなわち酸可溶Ａｌを0.01０以下
に制限する技術がある。しかし、Ａｌで脱酸しているの
でＡｌの酸化物が鋼中に残存するのは必然で、この鋼に
おいてもＡｌの酸化物による欠陥の発生は抑え得ないも
のであった。さらに、酸可溶Ａｌが残存しないように脱
酸すると脱酸不足が生じ、鋼中に気泡が残ることがしば
しば起き、ブローホールと呼ばれる欠陥により表面性状
を損ね、安定して実用化ができる技術ではなかった。[0005] Further, steel containing a large amount of acid-soluble Al in the steel has a high recrystallization temperature.
In an IF steel to which a carbonitride forming element such as described above is added, since fine carbonitrides are present in the steel, annealing must be performed at a higher temperature than that of a general low-carbon Al-killed steel. To solve this problem, Japanese Patent Application Laid-Open No. 62-308
As disclosed in Japanese Patent Publication No. 22-222, there is a technique in which excess Al other than that used for deoxidation, that is, acid-soluble Al, is limited to 0.010 or less, although deoxidation is performed using Al. However, since Al is deoxidized, it is inevitable that Al oxide remains in the steel, and the generation of defects due to Al oxide cannot be suppressed even in this steel. Furthermore, when deoxidizing so that acid-soluble Al does not remain, insufficient deoxidation occurs, and air bubbles often remain in the steel, which impairs the surface properties due to defects called blow holes, and is a technology that can be stably commercialized. Was not.
【０００６】本発明は上記課題を有利に解決するために
なされたものであり、鋼中の介在物を微細でかつ、部分
的に固い晶出相がなく介在物全体が変形・破砕しやすい
組成の介在物にコントロールし、低コストで介在物欠陥
を少なくして、さらに鋼中の酸可溶Ａｌの含有量を極め
て少なくできるので、再結晶温度が低く、従来と同等の
温度で焼鈍したときに高いプレス成形性を得ることがで
きる鋼板およびその製造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 to advantageously solve the above-mentioned problems, and has a composition in which inclusions in steel are fine and partially free of a hard crystallization phase, and the entire inclusion is easily deformed and fractured. Since the inclusions can be controlled to reduce inclusion defects at low cost and further reduce the content of acid-soluble Al in the steel, the recrystallization temperature is low, and when annealing at the same temperature as before It is an object of the present invention to provide a steel sheet capable of obtaining high press formability and a method for producing the same.
【０００７】[0007]
【課題を解決するための手段】本発明の特徴とするとこ
ろは、（１）重量％で、Ｃ ：０．０００１〜０．００
７０％、Ｓｉ：０．００１〜２．０％、Ｍｎ：０．０５
〜３．０％、Ｐ：０．００１〜０．１５０％、Ｓ：０．
００１〜０．０５０％、Ｎ：０．０００５〜０．００８
０％、酸可溶Ａｌ：０．００５％以下、Ｔｉ：０．００
４〜０．０４０％を含有し、残部鉄および不可避的不純
物よりなる鋼に、鋼中にチタン酸化物、マンガン酸化
物、シリコン酸化物、アルミナが主成分で、アルミナが
３０％以下含む酸化物系介在物を含有せしめたことを特
徴とする欠陥が少なくプレス成形性に優れた薄鋼板。及
び精錬後の溶鋼の鋼中酸素量を２５０ｐｐｍ以下に脱酸
し、ついでＴｉを添加してＣ：０．０００１〜０．００
７０％、Ｓｉ：０．００１〜２．０％、Ｍｎ：０．０５
〜３．０％、Ｐ：０．００１〜０．１５０％、Ｓ：０．
００１〜０．０５０％、Ｎ：０．０００５〜０．００８
０％、酸可溶Ａｌ：０．００５％以下、Ｔｉ：０．００
４〜０．０４０％を含有し、残部鉄および不可避的不純
物よりなる鋼に、鋼中にチタン酸化物、マンガン酸化
物、シリコン酸化物、アルミナが主成分で、アルミナが
３０％以下含む酸化物系介在物を含有せしめた鋼を連続
鋳造−熱間圧延の後、６００℃〜８００℃で巻取って、
ついで脱スケール処理を施し、その後５０％〜９５％の
圧延率で冷間圧延を施し、６５０〜９００℃の温度範囲
で焼鈍を施すことを特徴とする欠陥が少なくプレス成形
性に優れた薄鋼板の製造方法である。The features of the present invention are as follows: (1) C: 0.0001 to 0.00% by weight.
70%, Si: 0.001 to 2.0%, Mn: 0.05
-3.0%, P: 0.001-0.150%, S: 0.
001 to 0.050%, N: 0.0005 to 0.008
0%, acid-soluble Al: 0.005% or less, Ti: 0.00
A steel containing 4 to 0.040%, the balance being iron and unavoidable impurities, and an oxide containing titanium oxide, manganese oxide, silicon oxide, and alumina as main components and containing 30% or less of alumina. Thin steel sheet excellent in press formability with few defects characterized by containing system inclusions. And the oxygen content in the steel of the molten steel after the refining is deoxidized to 250 ppm or less, and then Ti is added to make C: 0.0001 to 0.00
70%, Si: 0.001 to 2.0%, Mn: 0.05
-3.0%, P: 0.001-0.150%, S: 0.
001 to 0.050%, N: 0.0005 to 0.008
0%, acid-soluble Al: 0.005% or less, Ti: 0.00
A steel containing 4 to 0.040%, the balance being iron and unavoidable impurities, and an oxide containing titanium oxide, manganese oxide, silicon oxide, and alumina as main components and containing 30% or less of alumina. After continuous casting-hot rolling of steel containing system inclusions, it is wound at 600 ° C to 800 ° C,
Then, descaling treatment is performed, then cold rolling is performed at a rolling ratio of 50% to 95%, and annealing is performed at a temperature range of 650 to 900 ° C. It is a manufacturing method of.
【０００８】[0008]
【発明の実施の形態】本発明者らは種々の組成の介在物
を人工的に合成して鋼中に埋め込み、実験室的に圧延実
験を行った。その結果、介在物中にアルミナを少量含有
しチタン酸化物（Ｔｉ０x 、Ｘ＝１．５〜２．０）、マ
ンガン酸化物（ＭｎＯ）、シリコン酸化物（Ｓｉ
０2 ）、アルミナ（Ａｌ2 ０3 ）を主成分とする組成の
介在物とすれば、融点が比較的低く、冷却時に高融点で
固い晶出相の生成が抑制でき、圧延等によって微細に破
砕されることを見出した。このようなアルミナ含有量お
よび組成の異なる介在物を分散させた鋼を実験室的に溶
製、鋳造し、通常の方法で熱間圧延、酸洗、冷間圧延、
焼鈍、調質圧延を行って薄鋼板とし、プレス成形を行っ
たが一部の鋼板で割れ等の欠陥が発生した。この欠陥付
近の調査を行った結果、欠陥部には伸延した介在物が検
出され、その大きさを測定して鋳片での大きさに換算す
るといずれも５０μｍより大きかったことが判った。BEST MODE FOR CARRYING OUT THE INVENTION The present inventors artificially synthesized inclusions having various compositions, embedded them in steel, and performed a rolling test in a laboratory. As a result, a small amount of alumina is contained in the inclusions, and titanium oxide (Ti0x, X = 1.5 to 2.0), manganese oxide (MnO), silicon oxide (Si
0 2 ) and an inclusion having a composition mainly composed of alumina (Al 2 O 3 ), the melting point is relatively low, and the formation of a hard crystallization phase with a high melting point upon cooling can be suppressed. Found to be crushed. Such a steel in which inclusions having different alumina contents and compositions are dispersed is melted and cast in a laboratory, and hot rolling, pickling, cold rolling, and the like are performed in a usual manner.
Annealing and temper rolling were performed to obtain a thin steel sheet, and press forming was performed, but defects such as cracks occurred in some steel sheets. As a result of investigating the vicinity of the defect, an elongated inclusion was detected in the defect portion, and it was found that the size was measured and converted into the size of a slab, and all were larger than 50 μm.
【０００９】以上のことより、鋳片で５０μｍ以下の上
記組成の介在物であれば欠陥とならないことが推測され
たため、５０μｍ以下のアルミナを３０重量％以下含有
し、チタン酸化物、マンガン酸化物、シリコン酸化物、
アルミナを主成分とする組成の介在物のみを分散させた
鋼を実験室的に溶製、鋳造し、通常の方法で熱間圧延、
酸洗、冷間圧延、焼鈍、調質圧延を行って鋼板とし、プ
レス成形を行ったところ、プレス成形性は良好であり、
欠陥の発生が極めて少ないことが確認できた。添加する
Ｔｉ濃度を変化させて実験を行った結果、チタン酸化
物、マンガン酸化物、シリコン酸化物、アルミナを主成
分（アルミナ含有量３０重量％以下）とする組成の介在
物とするには、Ｔｉ濃度を０．０４０％以下とすること
が必要である。これはＴｉが高すぎるとＴｉの脱酸力が
ＭｎやＳｉに比べて高いのでこれらの酸化物と複合せ
ず、アルミナと同様な高融点のチタン酸化物含有量の高
い介在物が生成することによる。一方、Ｔｉの下限を
０．００４％としたのは連続鋳造時に脱酸不足による気
泡の発生を防止するためである。Ｔｉ量は、脱酸に使用
された残りを用いてＣ、Ｎを析出固定するので好ましく
は、このＣ、Ｎの析出固定に必要な量に脱酸に必要な
０．００２％を加えた量以上とする。Ｃ、Ｎを析出固定
するために必要なＴｉ量は、Ｎｂの添加の有無によって
異なり、詳細は後述する。Ｔｉを添加した後にＡｌを添
加することで、Ａｌ添加時の酸素濃度が下がっており、
Ａｌの添加量が少なくて済み、生成する介在物中のアル
ミナ含有量も少なく、介在物中にアルミナが含有してい
てもプレス時に欠陥の発生はほとんどない。また、Ｔｉ
添加時に生成したチタン酸化物、マンガン酸化物、シリ
コン酸化物、アルミナを主成分とする組成の介在物はＡ
ｌによって還元されてしまわずにチタン酸化物、マンガ
ン酸化物、シリコン酸化物、アルミナを主成分とする介
在物となる。総Ａｌ量が０．００１％以上あれば酸素は
２０ppm 以下とすることができＣＯガスは発生せずに鋳
造が可能となり、かつＣＯガス起因の気孔が鋼材中に生
成するのを抑止することができる。[0009] From the above, it was presumed that inclusions having the above composition of 50 µm or less in the cast slab would not cause defects. Therefore, alumina containing 50 µm or less was contained in an amount of 30 wt% or less, and titanium oxide and manganese oxide were contained. , Silicon oxide,
Laboratory smelting and casting steel in which only inclusions having a composition mainly composed of alumina are dispersed, and hot-rolling by a normal method,
Pickling, cold rolling, annealing, temper rolling to form a steel sheet, and press forming, the press formability is good,
It was confirmed that the generation of defects was extremely small. As a result of an experiment in which the concentration of Ti to be added was changed, an inclusion having a composition containing titanium oxide, manganese oxide, silicon oxide, and alumina as main components (alumina content of 30% by weight or less) was obtained. It is necessary to make the Ti concentration 0.040% or less. This is because if Ti is too high, the deoxidizing power of Ti is higher than that of Mn or Si, so that it does not combine with these oxides, and the same inclusions as alumina with high melting point and high content of titanium oxide are formed. by. On the other hand, the lower limit of Ti is set to 0.004% in order to prevent bubbles from being generated due to insufficient deoxidation during continuous casting. The amount of Ti is preferably an amount obtained by adding 0.002% required for deoxidation to the amount necessary for the precipitation and fixation of C and N, since C and N are deposited and fixed using the residue used for deoxidation. Above. The amount of Ti required for precipitating and fixing C and N differs depending on whether Nb is added or not, and details will be described later. By adding Al after adding Ti, the oxygen concentration at the time of adding Al is reduced,
The addition amount of Al is small, the content of alumina in the formed inclusions is small, and even if alumina is contained in the inclusions, almost no defects occur during pressing. Also, Ti
Inclusions composed mainly of titanium oxide, manganese oxide, silicon oxide, and alumina generated during the addition are A
Without being reduced by l, it becomes an inclusion mainly composed of titanium oxide, manganese oxide, silicon oxide, and alumina. If the total Al content is 0.001% or more, oxygen can be reduced to 20 ppm or less, casting can be performed without generating CO gas, and generation of pores due to CO gas in steel can be suppressed. it can.
【００１０】次に本発明の製造法について詳述しながら
説明する。まず、転炉で０．０２〜０．１０％のＣを含
む溶鋼を溶製する。この際、溶鋼中のＣが所望するＣ濃
度より高い場合は出鋼後に真空脱ガス装置等による脱炭
処理を行い所定のＣ濃度まで低減する。所望するＣ濃度
より低い場合には出鋼後にＣ（加炭剤）を添加して所定
のＣ濃度としてもかまわない。また、溶鋼を出鋼する際
必要に応じてＦｅ−Ｍｎを投入してもよい。次に、出鋼
した溶鋼中へＭｎ、Ｓｉの１種または２種を添加する
か、真空脱ガス処理による予備脱酸を行って溶鋼中の酸
素を２５０ｐｐｍ以下とする。単体のアルミナを生成さ
せないためにはＴｉを添加するよりも前にＡｌを添加し
ないことが必要であり、Ｆｅ−ＭｎやＦｅ−Ｓｉを添加
してＭｎおよび／またはＳｉにより脱酸する際には、Ｍ
ｎやＳｉの添加量は脱酸時に添加するＴｉ合金中に含ま
れるＳｉやＭｎの含有量より増加する量を考慮して調整
すればよい。溶鋼中の酸素が２５０ｐｐｍより高くなる
と、Ｔｉ合金を多量に添加することが必要になり、後述
するように脱酸時の過飽和度が大きくなり、Ｔｉ添加時
にアルミナと同様の高融点のチタン酸化物が多数生成
し、複合介在物が安定して生成しないことがあり、ま
た、これらが凝集して大きな介在物となるおそれがあ
る。このようにしてして溶鋼中の酸素を２５０ｐｐｍ以
下に調整した溶鋼に、化学組成がＴｉ：１０〜７０重量
％の成分と残部はＦｅ、Ｍｎ、Ｓｉのうち１種から３種
および不可避的不純物とからなる合金を添加して、Ｔｉ
を溶鋼成分として０．００２〜０．０３０％含有させ
る。このように溶鋼中のＴｉ濃度を０．０３０％以下と
することでチタン酸化物、マンガン酸化物、シリカ、ア
ルミナを主成分とする組成の複合介在物とすることが可
能となる。溶鋼中のＴｉ濃度が高すぎるとＴｉの脱酸力
がＭｎやＳｉに比べて高いのでこれらの酸化物と複合せ
ず、アルミナと同様な高融点のチタン酸化物が主成分の
介在物となる。Next, the production method of the present invention will be described in detail. First, molten steel containing 0.02 to 0.10% C is melted in a converter. At this time, if the C in the molten steel is higher than the desired C concentration, the steel is subjected to a decarburization treatment by a vacuum degassing device or the like after tapping to reduce the C concentration to a predetermined C concentration. When the C concentration is lower than the desired C concentration, C (carburizing agent) may be added after tapping to set a predetermined C concentration. Further, when tapping molten steel, Fe-Mn may be added as needed. Next, one or two kinds of Mn and Si are added to the molten steel that has been tapped, or preliminary deoxidation is performed by vacuum degassing to reduce the oxygen in the molten steel to 250 ppm or less. In order not to generate single alumina, it is necessary not to add Al before adding Ti, and when adding Fe-Mn or Fe-Si and deoxidizing with Mn and / or Si, , M
The amount of addition of n or Si may be adjusted in consideration of an amount that is greater than the content of Si or Mn contained in the Ti alloy added at the time of deoxidation. If the oxygen in the molten steel is higher than 250 ppm, it is necessary to add a large amount of Ti alloy, and as described later, the degree of supersaturation at the time of deoxidation increases, and the titanium oxide having the same high melting point as alumina at the time of adding Ti May be generated in large numbers, and the composite inclusions may not be generated stably, or they may aggregate to form large inclusions. In this way, in the molten steel in which the oxygen in the molten steel was adjusted to 250 ppm or less, the chemical composition of Ti: 10 to 70% by weight, and the balance was Fe to Mn or Si and one to three kinds of inevitable impurities. An alloy consisting of
Of 0.002 to 0.030% as a molten steel component. By setting the Ti concentration in the molten steel to 0.030% or less as described above, it becomes possible to obtain a composite inclusion having a composition mainly composed of titanium oxide, manganese oxide, silica, and alumina. If the Ti concentration in the molten steel is too high, the deoxidizing power of Ti is higher than that of Mn or Si, so that it does not complex with these oxides, and the high melting point titanium oxide similar to alumina becomes the main component inclusion. .
【００１１】更に、脱酸時の過飽和度を小さくすれば核
生成速度が遅くなり、生成する介在物の個数及び介在物
径が小さくなる。過飽和度はＴｉと酸素の積で決まるの
で、過飽和度を小さくする方法として脱酸合金中のＴｉ
含有量を低くすることと脱酸時の溶鋼中の酸素を低くす
ることが有効である。脱酸合金中のＴｉ含有量が高い場
合には溶鋼中に添加した脱酸合金の周囲にＴｉ濃度の高
い部分が生成して過飽和度が高くなるので、Ｔｉ含有量
の低い脱酸合金を使用することが好ましい。そこで、溶
鋼中の酸素濃度と合金中Ｔｉ含有量を変化させた実験・
検討を行った結果、酸素濃度および合金中Ｔｉ含有量が
低くなるにしたがって介在物径は小さくなり、酸素を２
５０ｐｐｍ以下とし、かつ、Ｔｉ含有量が７０％以下の
合金で脱酸することで、最大でも５０μｍ以下の介在物
とすることができることを見出した。Ｔｉ含有量が高く
なると介在物径が大きくなるとともに、脱酸時にチタン
酸化物の含有量の高い介在物が生成し、それが溶鋼中に
残存し混在する。Ｔｉ含有量が低すぎると添加する合金
量が多くなりすぎ、溶鋼温度の低下が起こって、溶鋼の
凝固や鋳造が困難になったり、添加に時間がかかり生産
性に障害を与える。また、Ｔｉ含有量が高い場合には少
量ずつ添加すると部分的に過飽和度の高い部分が少なく
なり有効である。また、ＴｉをＦｅやＳｉ、Ｍｎとの合
金とすることで、Ｔｉの活量を下げるとともに部分的に
濃度の高い領域を減少させるために、過飽和度が一層減
少し、チタン酸化物、マンガン酸化物、シリカ、アルミ
ナ主体の複合介在物の生成を促進する。Ｔｉは１度に添
加してもよいが、２回以上に分割して添加してもよい。
Ｔｉは添加後に溶鋼中の酸素が高く鋳造時にＣＯガスが
発生して鋳型内溶鋼のボイリングが発生するおそれのあ
る場合には、Ｔｉ添加後にＡｌを０．００１％以上とな
る量添加してもよい。これによって酸素は２０ppm 以下
になり、ＣＯガス発生によるボイリングなしに鋳造が可
能となる。Ｔｉの添加による脱酸によって酸素が下げら
れているので、Ｔｉ添加前にＡｌを添加する場合よりも
Ａｌの添加量は少なくてすみ、生成する介在物の量が少
なく、粗大な介在物も生成しない。Ａｌを０．００５％
以下とすることで介在物はチタン酸化物、シリコン酸化
物、マンガン酸化物、３０％以下のアルミナを主成分と
する溶鋼中で液体状態で存在する介在物となる。このよ
うにして溶製した溶鋼は通常と同じ方法でタンディシュ
を通して、連続鋳造機で鋳造することが可能である。Further, if the degree of supersaturation at the time of deoxidation is reduced, the nucleation rate is reduced, and the number of inclusions and the diameter of the inclusions are reduced. Since the degree of supersaturation is determined by the product of Ti and oxygen, as a method of reducing the degree of supersaturation, Ti
It is effective to reduce the content and oxygen in the molten steel at the time of deoxidation. If the Ti content in the deoxidized alloy is high, a portion with a high Ti concentration is formed around the deoxidized alloy added to the molten steel and the degree of supersaturation increases, so use a deoxidized alloy with a low Ti content. Is preferred. Therefore, experiments in which the oxygen concentration in the molten steel and the Ti content in the alloy were changed
As a result of the investigation, the inclusion diameter became smaller as the oxygen concentration and the Ti content in the alloy became lower, and oxygen was reduced to 2%.
It has been found that by performing deoxidation with an alloy having a content of 50 ppm or less and a Ti content of 70% or less, inclusions having a maximum size of 50 μm or less can be obtained. Increasing the Ti content increases the diameter of the inclusions, and at the time of deoxidation, generates inclusions having a high content of titanium oxide, which remain and are mixed in the molten steel. If the Ti content is too low, the amount of the alloy to be added becomes too large, and the temperature of the molten steel decreases, so that solidification and casting of the molten steel become difficult, and the addition takes a long time, which impairs productivity. In addition, when the Ti content is high, it is effective to add a small amount at a time, since a portion having a high degree of supersaturation partially decreases. In addition, by using Ti as an alloy with Fe, Si, and Mn, the activity of Ti is reduced and a region having a high concentration is partially reduced, so that the degree of supersaturation is further reduced, and titanium oxide and manganese oxide are reduced. Promotes the formation of composite inclusions mainly composed of materials, silica and alumina. Ti may be added at once, or may be added in two or more portions.
In the case where the oxygen in the molten steel is high after the addition of Ti and CO gas is generated at the time of casting and there is a possibility that boiling of the molten steel in the mold may occur, even if Al is added in an amount of 0.001% or more after the addition of Ti. Good. This reduces the oxygen to 20 ppm or less and enables casting without boiling due to CO gas generation. Since oxygen is reduced by deoxidation due to the addition of Ti, the amount of Al added can be smaller than in the case where Al is added before Ti addition, the amount of inclusions generated is small, and coarse inclusions are also generated. do not do. 0.005% of Al
By setting the content as described below, the inclusions become inclusions existing in a liquid state in molten steel containing titanium oxide, silicon oxide, manganese oxide, and 30% or less alumina as main components. The molten steel thus smelted can be cast through a tundish by a continuous casting machine in the same manner as usual.
【００１２】最終的に鋼中に含有されるＭｎの含有量
は、０．０５％未満に下げるのは精錬時間が長くなり経
済性を大きく損ねるので、０．０５％を下限とし、３．
０％を越えると鋼板の加工性が大幅に劣化し、高い加工
性の期待できなくなる、３．０％を上限とする。Ｓｉ量
は、０．００１％未満に下げるのは十分な予備処理等が
必要で精錬に大幅なコスト負担をかけ経済性を損ねるの
で０．００１％を下限とし、２．０％を越えると加工性
が大幅に劣化するので２．０％を上限とする。Ｐは、
０．００１％未満に下げることは溶銑予備処理に時間と
コストがかかり、経済性を大きく損ねるので、０．００
１％を下限とし、０．０５０％を越えると加工性が劣化
するので０．０５０％を上限とする。Ｓは、０．００１
％未満に下げることは溶銑予備処理に時間とコストがか
かり、経済性を大きく損ねるので、０．００１％を下限
とし、０．０３０％を越えると加工性・耐食性が劣化す
るので０．０３０％を上限とする。Ｎは、０．０００５
％未満に下げることは精錬の段階での大幅なコスト上昇
を伴い経済性を大きく損ねるので、０．０００５％を下
限とし、０．００８０％を越えると、Ｎを固溶Ｎをなく
すためのＴｉ添加量が多く必要で、本願の目的である介
在物の形態制御が不可能になるので、０．００８０％を
上限とする。固溶Ｎ量を少なくするために、ＮをＴｉＮ
として固定するには、前述のように少なくともＴｉ
［％］＞３．４３Ｎ［％］とする必要がある。さらに、
加工性を向上させるためには、ＴｉはＣとの当量以上添
加することが好ましい。この場合のＴｉ添加量は、[0012] If the content of Mn finally contained in the steel is reduced to less than 0.05%, the refining time becomes longer and the economic efficiency is greatly impaired.
If it exceeds 0%, the workability of the steel sheet is significantly deteriorated, and high workability cannot be expected. The upper limit is 3.0%. If the amount of Si is reduced to less than 0.001%, sufficient pre-treatment is required, so that refining costs a great deal of cost and impairs economic efficiency. Therefore, the upper limit is set to 2.0% because the property is greatly deteriorated. P is
Lowering the content to less than 0.001% requires time and cost for hot metal pretreatment and greatly impairs economic efficiency.
The lower limit is 1%, and if it exceeds 0.050%, the workability deteriorates, so the upper limit is 0.050%. S is 0.001
If the content is reduced to less than 0.1%, it takes time and cost for the hot metal pretreatment, and the economic efficiency is greatly impaired. Therefore, the lower limit is 0.001%. Is the upper limit. N is 0.0005
% Lowers 0.0005% as the lower limit, and if it exceeds 0.0080%, Ti for eliminating N solute N is not used. Since a large amount of addition is required, and it is impossible to control the form of inclusions, which is the object of the present invention, the upper limit is 0.0080%. To reduce the amount of solute N, N
As described above, at least Ti
[%]> 3.43 N [%]. further,
In order to improve the workability, it is preferable to add Ti in an amount equal to or more than C. In this case, the amount of Ti added is
【数１】 Ｔｉ［％］＞４Ｃ［％］＋３．４３Ｎ［％］ となる。Ｔｉの上限は、０．０４０％とする。この量を
越えると、脱酸時にＴｉを大量に加えなければならなく
なり、本願発明の特徴とする介在物組成が得られなくな
るためである。Ｎｂは、加工性を向上させるため、主と
してＣを析出固定するために添加する。添加量として
は、好ましくは、Ｔｉを添加しない場合は、Ｎｂ［％］
＞６．６４Ｎ［％］、Ｔｉを添加してＮを析出固定した
場合は、Ｎｂ＞０．８×７．７５Ｃ［％］を添加する。
添加量の下限としては、０．００４％未満では、加工性
を向上させる効果がなくなるので、０．００４％を下限
とし、０．０５０％を越えると、固溶Ｎｂの存在により
かえって加工性を劣化させることになるので、０．０５
０％を上限とする。Ｂは、２次加工脆性を防止するため
に添加する。Ｂは、結晶粒界に存在する固溶Ｃがなくな
った時にしばしば見られる２次加工脆性と呼ばれる脆化
を防止するのに有効な元素であり、厳しい絞り加工が加
えられる部品に本願発明鋼板が適用される時などに添加
する。添加量は、０．０００４％未満では、２次加工脆
性を防止する効果がなくなるので、０．０００４％を下
限とし、０．００７０％を越えると、再結晶温度が高く
なるなどの弊害が出て、通常の鋼板製造のプロセスでは
製造しにくくなるため０．００７０％を上限とする。[Formula 1] Ti [%]> 4C [%] + 3.43N [%] The upper limit of Ti is set to 0.040%. If this amount is exceeded, a large amount of Ti must be added during deoxidation, and the inclusion composition characteristic of the present invention cannot be obtained. Nb is added mainly to precipitate and fix C in order to improve workability. As the amount of addition, preferably, when Ti is not added, Nb [%]
> 6.64 N [%], and when N is precipitated and fixed by adding Ti, Nb> 0.8 × 7.75 C [%] is added.
If the lower limit of the addition amount is less than 0.004%, the effect of improving workability is lost, so the lower limit is 0.004%, and if it exceeds 0.050%, the workability is rather reduced due to the presence of solid solution Nb. 0.05
0% is the upper limit. B is added in order to prevent secondary working brittleness. B is an element effective in preventing embrittlement, which is often referred to as secondary working embrittlement, which is often seen when solid solution C present at the crystal grain boundaries disappears. It is added when it is applied. If the addition amount is less than 0.0004%, the effect of preventing secondary working brittleness is lost, so the lower limit is 0.0004%, and if it exceeds 0.0070%, adverse effects such as an increase in the recrystallization temperature are caused. Therefore, the upper limit is 0.0070% because it is difficult to manufacture the steel sheet in a normal steel sheet manufacturing process.
【００１３】このようにして溶製した溶鋼を通常と同じ
方法でタンディッシュを通して、連続鋳造機で鋳造す
る。さらに、この鋳片は通常と同じ方法で熱間圧延した
後、６００℃〜８００℃の温度範囲で巻取りを行う。た
だ単にＴｉ量をＮとの当量以上加えても、Ｎは全量Ｔｉ
Ｎとして析出することはないので、巻取温度を６００℃
〜８００℃の範囲として、極力ＮをＴｉＮとして析出さ
せ、固溶Ｎ量を２ｐｐｍ以下とする。固溶Ｎ量２ｐｐｍ
超では、割れの感受性が増し、５０μｍ程度の大きさの
介在物でも割れが発生するようになるとともに、時効性
が劣化し、ストレチャーストレインと呼ばれる欠陥が発
生するので、固溶Ｎ量としては２ｐｐｍ以下とする。巻
取温度６００℃未満ではＴｉによるＮの析出固定が不十
分で、固溶Ｎが２ｐｐｍを越えて存在するようになり、
介在物による割れの感受性が劣化するとともに、製品で
の時効性が劣化するので６００℃を下限とし、８００℃
を越えると、結晶粒が粗大化して冷延焼鈍後に高いｒ値
が得られなくなるので８００℃を上限とする。ついで、
脱スケール処理を行う。一般には酸洗を施すが、機械的
にスケール除去を行っても良い。その後、冷間圧延を行
い、連続焼鈍を行う。連続焼鈍の温度は、６５０℃〜90
０９００℃とする。６５０℃未満では再結晶せず、加工
性が劣化するので６５０℃を下限とし、９００℃を越え
ると鋼板の高温強度が弱まり、連続焼鈍炉内で絞りと呼
ばれる現象を起こし、破断するなどの問題が生じやすく
なるので９００℃を上限とする。その後、スキンパス圧
延を施し鋼板とする。また、その後、耐食性、意匠性の
ためにめっき、樹脂コーティング等を施すことも可能で
ある。連続焼鈍は、溶融亜鉛めっきラインで行っても良
く、焼鈍後直ちに、溶融めっきを施し、溶融亜鉛めっき
鋼板、合金化溶融亜鉛めっき鋼板、溶融アルミめっき鋼
板等の熱漬めっき鋼板とすることもできる。The molten steel thus produced is passed through a tundish in the same manner as usual and cast by a continuous casting machine. Further, the slab is hot-rolled by the same method as usual, and then wound in a temperature range of 600 ° C to 800 ° C. Even if the amount of Ti is simply added to the equivalent of N or more, the total amount of N becomes Ti
Since it does not precipitate as N, the winding temperature is 600 ° C.
Within the range of ~ 800 ° C, N is precipitated as much as possible as TiN, and the amount of solute N is set to 2 ppm or less. 2ppm of solute N
In the case of exceeding, the sensitivity of cracking is increased, cracks occur even with inclusions having a size of about 50 μm, aging property is deteriorated, and a defect called a strainer strain is generated. 2 ppm or less. If the winding temperature is lower than 600 ° C., precipitation and fixation of N by Ti is insufficient, and solute N is present in excess of 2 ppm.
Since the susceptibility to cracks due to inclusions deteriorates and the aging property of the product deteriorates, the lower limit is set at 600 ° C and 800 ° C.
Is exceeded, the crystal grains become coarse and a high r value cannot be obtained after cold rolling annealing. Therefore, the upper limit is set to 800 ° C. Then
Perform descaling. Generally, pickling is performed, but scale removal may be performed mechanically. Thereafter, cold rolling is performed and continuous annealing is performed. The temperature of the continuous annealing is from 650 ° C. to 90
0900 ° C. If the temperature is lower than 650 ° C., recrystallization does not occur and the workability is deteriorated. Therefore, the lower limit is 650 ° C., and if it exceeds 900 ° C., the high-temperature strength of the steel sheet is weakened, causing a phenomenon called drawing in a continuous annealing furnace and causing problems such as breakage. Therefore, the upper limit is set at 900 ° C. After that, skin pass rolling is performed to obtain a steel sheet. Thereafter, plating, resin coating, or the like can be performed for corrosion resistance and design. The continuous annealing may be performed in a hot-dip galvanizing line, or immediately after the annealing, hot-dip galvanized steel sheet, alloyed hot-dip galvanized steel sheet, hot-dipped galvanized steel sheet, etc. .
【００１４】[0014]
【実施例】２７０トン転炉で表１に示す成分の鋼を溶製
した。さらにこの溶鋼に真空脱ガス処理を施すとともに
表２に示す脱酸剤を添加し酸素濃度および介在物組成を
調整した。その後、連続鋳造して鋼塊となした。得られ
た鋼の成分及び塊中の介在物の組成とサイズを合わせて
表３および表４に示す。ついで、熱間圧延を行った。そ
の際の仕上圧延、巻取りは、表５に示す温度で行った。
ついで、酸洗、冷間圧延を行った後、表５に示す温度で
焼鈍を行った。表５には、焼鈍を行う前に測定した再結
晶温度も示しておく。焼鈍後、１％の圧下率でスキンパ
ス圧延を施し、冷延鋼板とした。得られた冷延鋼板を用
いて、絞り比２．２でそれぞれ約１万個の加工を行っ
た。このとき発生した介在物起因による割れの個数を調
査し、プレス時の欠陥発生率を求めた。結果を表５に示
す。表５から、本願発明法では、比較法に比べて再結晶
温度が低く、低い焼鈍温度でも比較材と同等の機械的特
性値が得られている。また、本願発明法では、比較法に
比べて、プレス時の欠陥発生率が極めて小さいことがわ
かる。EXAMPLES Steel having the components shown in Table 1 was melted in a 270 ton converter. Further, the molten steel was subjected to a vacuum degassing treatment, and a deoxidizing agent shown in Table 2 was added to adjust the oxygen concentration and the inclusion composition. Thereafter, it was continuously cast into a steel ingot. Tables 3 and 4 show the components of the obtained steel and the composition and size of the inclusions in the lump. Next, hot rolling was performed. The finish rolling and winding at that time were performed at the temperatures shown in Table 5.
Then, after performing pickling and cold rolling, annealing was performed at the temperatures shown in Table 5. Table 5 also shows the recrystallization temperature measured before annealing. After annealing, skin pass rolling was performed at a rolling reduction of 1% to obtain a cold-rolled steel sheet. Using the obtained cold-rolled steel sheet, about 10,000 pieces were each processed at a drawing ratio of 2.2. The number of cracks caused by inclusions generated at this time was investigated, and the defect occurrence rate at the time of pressing was determined. Table 5 shows the results. Table 5 shows that the recrystallization temperature is lower in the method of the present invention than in the comparative method, and mechanical property values equivalent to those of the comparative material are obtained even at a low annealing temperature. In addition, it can be seen that the method of the present invention has a significantly lower defect occurrence rate during pressing than the comparative method.
【００１５】[0015]
【発明の効果】本発明によれば、鋼中介在物を微細化
し、製造時の介在物による欠陥を著しく低減することが
できるとともに、再結晶温度を低下させることができる
ので、従来よりも低い温度での焼鈍が可能で、品質、経
済性ともに優れた欠陥の少ないプレス成形用鋼板を得る
ことができる等の優れた効果が得られる。According to the present invention, inclusions in steel can be made finer, defects due to inclusions during production can be significantly reduced, and the recrystallization temperature can be lowered. Annealing at a temperature is possible, and excellent effects such as being able to obtain a steel sheet for press forming excellent in both quality and economy and with few defects are obtained.
【００１６】[0016]
【表１】 [Table 1]
【００１７】[0017]
【表２】 [Table 2]
【００１８】[0018]
【表３】 [Table 3]
【００１９】[0019]
【表４】 [Table 4]
【００２０】[0020]
【表５】 [Table 5]
Claims (9)
鋼中にチタン酸化物、マンガン酸化物、シリコン酸化
物、アルミナが主成分で、アルミナが３０％以下含む酸
化物系介在物を含有せしめたことを特徴とする欠陥が少
なくプレス成形性に優れた薄鋼板。C: 0.0001 to 0.0070%, Si: 0.001 to 2.0%, Mn: 0.05 to 3.0%, P: 0.001 to 0. 150%, S: 0.001 to 0.050%, N: 0.0005 to 0.0080%, Acid-soluble Al: 0.005% or less, Ti: 0.004 to 0.040%, Steel consisting of the balance iron and unavoidable impurities,
Featuring titanium oxide, manganese oxide, silicon oxide and alumina as main components and containing oxide-based inclusions containing 30% or less of alumina, the steel has few defects and excellent press formability. Sheet steel.
せしめたことを特徴とする請求項１に記載の欠陥が少な
くプレス成形性に優れた薄鋼板。2. The thin steel sheet having a small number of defects and excellent in press formability according to claim 1, wherein Nb: 0.004 to 0.050% is contained.
有せしめたことを特徴とする請求項１または請求項２に
記載の欠陥が少なくプレス成形性に優れた薄鋼板。3. The thin steel sheet according to claim 1, wherein B: 0.0004 to 0.0050% is contained, and the defect is small and the press formability is excellent.
ｍ以下に脱酸し、ついでＴｉを添加してＣ：０．０００
１〜０．００７０％、Ｓｉ：０．００１〜２．０％、Ｍ
ｎ：０．０５〜３．０％、Ｐ：０．００１〜０．１５０
％、Ｓ：０．００１〜０．０５０％、Ｎ：０．０００５
〜０．００８０％、酸可溶Ａｌ：０．００５％以下、Ｔ
ｉ：０．００４〜０．０４０％を含有し、残部鉄および
不可避的不純物よりなる鋼に、鋼中にチタン酸化物、マ
ンガン酸化物、シリコン酸化物、アルミナが主成分で、
アルミナが３０％以下含む酸化物系介在物を含有せしめ
た鋼を連続鋳造−熱間圧延の後、６００℃〜８００℃で
巻取って、ついで脱スケール処理を施し、その後５０％
〜９５％の圧延率で冷間圧延を施し、６５０〜９００℃
の温度範囲で焼鈍を施すことを特徴とする欠陥が少なく
プレス成形性に優れた薄鋼板の製造方法。4. The oxygen content in the molten steel after refining is 250 pp.
m or less, and then Ti is added to add C: 0.000
1 to 0.0070%, Si: 0.001 to 2.0%, M
n: 0.05-3.0%, P: 0.001-0.150
%, S: 0.001 to 0.050%, N: 0.0005
0.0080%, acid-soluble Al: 0.005% or less, T
i: steel containing 0.004 to 0.040%, the balance being iron and unavoidable impurities, with titanium oxide, manganese oxide, silicon oxide, and alumina as main components in the steel,
After continuous casting and hot rolling, the steel containing oxide-based inclusions containing 30% or less of alumina is wound at 600 ° C to 800 ° C, then descaled, and then 50%
Cold rolled at a rolling rate of ~ 95%, 650-900 ° C
A method for producing a thin steel sheet having few defects and excellent press formability, characterized by annealing in the above temperature range.
またはＢ：０．０００４〜０．００５０％を含有せしめ
たことを特徴とする請求項４に記載の欠陥が少なくプレ
ス成形性に優れた薄鋼板の製造方法。5. Nb: 0.004 to 0.050% and / or
5. The method for producing a thin steel sheet according to claim 4, wherein B contains 0.0004 to 0.0050% and has few defects and excellent press formability.
中酸素量を２５０ｐｐｍ以下に脱酸した後、Ｔｉを添加
することを特徴とする請求項４記載の欠陥が少なくプレ
ス成形性に優れた薄鋼板の製造方法。6. The method according to claim 4, wherein the molten steel after refining is subjected to vacuum degassing to deoxidize the oxygen content in the steel to 250 ppm or less, and then Ti is added. Method for manufacturing thin steel sheets with excellent quality.
鋼中酸素量を２５０ｐｐｍ以下に脱酸した後、Ｔｉを添
加することを特徴とする請求項４記載の欠陥が少なくプ
レス成形性に優れた薄鋼板の製造方法。7. Addition of one or two of Si and Mn,
5. The method according to claim 4, wherein Ti is added after deoxidizing the oxygen content in the steel to 250 ppm or less.
以下に脱酸した後、化学組成がＴｉ：１０〜７５％、残
りＦｅ、Ｍｎ、Ｓｉの１種〜３種及び不可避的不純物か
らなる合金を添加することを特徴とする請求項４または
請求項５に記載の欠陥が少なくプレス成形性に優れた薄
鋼板の製造方法。8. The oxygen content of the molten steel after refining is 250 ppm.
5. The method according to claim 4, wherein after deoxidation, an alloy having a chemical composition of 10 to 75% of Ti and the remaining one to three of Fe, Mn, and Si and inevitable impurities is added. 5. The method for producing a thin steel sheet having few defects described in 5 and excellent in press formability.
０〜８０重量％、残りＦｅ、Ｍｎ、Ｓｉの１種〜３種及
び不可避的不純物からなる合金を添加して行うことを特
徴とする請求項４または請求項５または請求項６に記載
の欠陥が少なくプレス成形性に優れた薄鋼板の製造方
法。9. When adding Al, the chemical composition is Al: 1.
7. The defect according to claim 4, wherein said alloy is formed by adding an alloy consisting of 0 to 80% by weight, the remaining one, three or more of Fe, Mn, and Si and inevitable impurities. A method for producing thin steel sheets with little press formability.
Priority Applications (1)
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|---|---|---|---|
| JP03514897A JP3436857B2 (en) | 1997-02-19 | 1997-02-19 | Thin steel sheet excellent in press formability with few defects and method for producing the same |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP03514897A JP3436857B2 (en) | 1997-02-19 | 1997-02-19 | Thin steel sheet excellent in press formability with few defects and method for producing the same |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH10226843A true JPH10226843A (en) | 1998-08-25 |
| JP3436857B2 JP3436857B2 (en) | 2003-08-18 |
Family
ID=12433829
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP03514897A Expired - Fee Related JP3436857B2 (en) | 1997-02-19 | 1997-02-19 | Thin steel sheet excellent in press formability with few defects and method for producing the same |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3436857B2 (en) |
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| EP1029938A2 (en) * | 1999-02-18 | 2000-08-23 | Nippon Steel Corporation | Rolled steel having few inclusion defects |
| JP2001303182A (en) * | 2000-04-24 | 2001-10-31 | Nippon Steel Corp | Steel sheet for can good in workability and small in defect and its producing method |
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| EP1029938A3 (en) * | 1999-02-18 | 2003-10-15 | Nippon Steel Corporation | Rolled steel having few inclusion defects |
| EP1029938A2 (en) * | 1999-02-18 | 2000-08-23 | Nippon Steel Corporation | Rolled steel having few inclusion defects |
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| US9340860B2 (en) | 2007-03-05 | 2016-05-17 | Nippon Steel & Sumitomo Metal Corporation | Cold-rolled steel sheet and galvannealed steel sheet |
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| JP2010059477A (en) * | 2008-09-03 | 2010-03-18 | Sumitomo Metal Ind Ltd | High tensile strength cold rolled steel sheet |
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