JPS6338556A - Cold rolled steel sheet for deep drawing having superior resistance to cracking by secondary working and its manufacture - Google Patents
Cold rolled steel sheet for deep drawing having superior resistance to cracking by secondary working and its manufactureInfo
- Publication number
- JPS6338556A JPS6338556A JP18305186A JP18305186A JPS6338556A JP S6338556 A JPS6338556 A JP S6338556A JP 18305186 A JP18305186 A JP 18305186A JP 18305186 A JP18305186 A JP 18305186A JP S6338556 A JPS6338556 A JP S6338556A
- Authority
- JP
- Japan
- Prior art keywords
- steel sheet
- steel
- cold
- carburized layer
- thickness
- 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.)
- Granted
Links
- 238000005336 cracking Methods 0.000 title claims abstract description 38
- 239000010960 cold rolled steel Substances 0.000 title claims abstract description 34
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 9
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 57
- 239000010959 steel Substances 0.000 claims abstract description 57
- 238000000137 annealing Methods 0.000 claims abstract description 21
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 16
- 229910000859 α-Fe Inorganic materials 0.000 claims abstract description 15
- 238000009849 vacuum degassing Methods 0.000 claims abstract description 6
- 238000001953 recrystallisation Methods 0.000 claims abstract description 5
- 229910052804 chromium Inorganic materials 0.000 claims description 10
- 229910052758 niobium Inorganic materials 0.000 claims description 10
- 238000005096 rolling process Methods 0.000 claims description 5
- 238000000034 method Methods 0.000 claims description 4
- 238000010438 heat treatment Methods 0.000 claims description 3
- 230000009467 reduction Effects 0.000 claims description 3
- 229910001209 Low-carbon steel Inorganic materials 0.000 claims description 2
- 238000007796 conventional method Methods 0.000 claims description 2
- 239000010410 layer Substances 0.000 abstract description 39
- 239000002344 surface layer Substances 0.000 abstract description 17
- 239000000203 mixture Substances 0.000 abstract description 6
- 238000005097 cold rolling Methods 0.000 abstract description 5
- 238000012360 testing method Methods 0.000 description 19
- 238000012545 processing Methods 0.000 description 9
- 230000000694 effects Effects 0.000 description 8
- 238000005098 hot rolling Methods 0.000 description 7
- 238000005255 carburizing Methods 0.000 description 6
- 230000000052 comparative effect Effects 0.000 description 5
- 239000000047 product Substances 0.000 description 5
- 238000009749 continuous casting Methods 0.000 description 4
- 230000006866 deterioration Effects 0.000 description 4
- 238000007747 plating Methods 0.000 description 4
- 238000005204 segregation Methods 0.000 description 4
- 239000000126 substance Substances 0.000 description 4
- 230000015572 biosynthetic process Effects 0.000 description 3
- 238000005554 pickling Methods 0.000 description 3
- 238000010926 purge Methods 0.000 description 3
- 229920006395 saturated elastomer Polymers 0.000 description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- 230000032683 aging Effects 0.000 description 2
- 238000004458 analytical method Methods 0.000 description 2
- 230000003712 anti-aging effect Effects 0.000 description 2
- 230000002542 deteriorative effect Effects 0.000 description 2
- 238000004453 electron probe microanalysis Methods 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 229910052748 manganese Inorganic materials 0.000 description 2
- 150000004767 nitrides Chemical class 0.000 description 2
- 230000001737 promoting effect Effects 0.000 description 2
- 238000002791 soaking Methods 0.000 description 2
- 239000006104 solid solution Substances 0.000 description 2
- 238000009628 steelmaking Methods 0.000 description 2
- 150000003568 thioethers Chemical class 0.000 description 2
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 230000000996 additive effect Effects 0.000 description 1
- 238000004220 aggregation Methods 0.000 description 1
- 230000002776 aggregation Effects 0.000 description 1
- 230000003679 aging effect Effects 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 229910002091 carbon monoxide Inorganic materials 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 238000007872 degassing Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 239000000428 dust Substances 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 238000001000 micrograph Methods 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 239000003507 refrigerant Substances 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- 238000004381 surface treatment Methods 0.000 description 1
- 238000009966 trimming Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
- 229910052725 zinc Inorganic materials 0.000 description 1
- 239000011701 zinc Substances 0.000 description 1
Landscapes
- Solid-Phase Diffusion Into Metallic Material Surfaces (AREA)
- Heat Treatment Of Steel (AREA)
- Heat Treatment Of Sheet Steel (AREA)
Abstract
Description
【発明の詳細な説明】
〔産業上の利用分野〕
本発明は、耐二次加工割れ性の優れた深絞り用冷延鋼板
およびその製造方法に関する。DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a cold-rolled steel sheet for deep drawing with excellent resistance to secondary work cracking and a method for producing the same.
例えば、自動車のクォーターパネル、オイルパンおよび
異形エアクリーナーケースのような部材は、非常に苛酷
なプレス加工によって成形される。For example, parts such as automobile quarter panels, oil pans, and irregularly shaped air cleaner cases are formed by extremely severe press working.
このような成形品の製造に使用される冷延鋼板には、高
い延性、超深絞り性および非時効性が要求される。この
要求に対し、炭窒化物形成元素であるＴ１．Ｎｂおよび
Ｃｒを単独または複合添加することによって、鋼中のＣ
やＮを固定して延性を高め且つ非時効性を確保すると共
に、ＴｉやＮｂの炭窒化物の作用によって、深絞り性の
向上に有効な（１１１１面方位０単結晶集合組織を発達
させた深絞り用非時効性冷延鋼板を使用することが、既
に提亥されている。Cold-rolled steel sheets used for manufacturing such molded products are required to have high ductility, ultra-deep drawability, and anti-aging properties. In response to this requirement, T1, which is a carbonitride forming element. By adding Nb and Cr alone or in combination, C in steel can be reduced.
In addition to increasing ductility and ensuring non-aging properties by fixing N and N, the action of Ti and Nb carbonitrides is effective in improving deep drawability. It has already been proposed to use non-aging cold rolled steel sheets for deep drawing.
例えば、特公昭４４−１８０６６号公報、特開昭５９−
６７３２２号公報および特開昭５９−８９７２７号公報
は、Ｔｉ添加鋼を、特公昭５４−１２４５号公報、特公
昭５９−３４７７８号公報および特開昭５８−８１９５
２号公報は、Ｎｂ添加鋼を、特公昭５０−３０５７２号
公報および特開昭５８−１８５７２号公報は、Ｔｉ−Ｃ
ｒ添加鋼を、特開昭５９−６７３１７号公報は、Ｔｉ−
Ｎｂ添加鋼を、特開昭５９−１２３７２０号公報は、Ｔ
ｉ−Ｎｂ−Ｃｒ添加鋼を、特開昭５９−１４０３３３号
公報は、Ｔｉ−Ｂ添加鋼を、そして特開昭５９−１９３
２２１号公報は、Ｔｉ−Ｎｂ−Ｂ添加鋼をそれぞれ開示
する。For example, Japanese Patent Publication No. 44-18066, Japanese Patent Application Publication No. 59-1988
67322 and JP-A-59-89727 disclose Ti-added steel as described in JP-A-54-1245, JP-A-59-34778 and JP-A-58-8195.
No. 2 uses Nb-added steel, and Japanese Patent Publication No. 50-30572 and Japanese Patent Application Laid-Open No. 58-18572 use Ti-C.
JP-A-59-67317 discloses Ti-
JP-A No. 59-123720 describes Nb-added steel as T
JP-A No. 59-140333 discloses i-Nb-Cr added steel, and JP-A No. 59-140333 discloses Ti-B added steel.
Publication No. 221 discloses Ti-Nb-B added steel, respectively.
〔発明が解決しようとする問題点〕
前記の公報に記載された。炭窒化物形成元素により鋼中
のＣおよびＮを充分に固定した超深絞り用冷延調板のう
ち、Ｂを添加していないものには。[Problems to be solved by the invention] This was described in the above-mentioned publication. Among cold-rolled plates for ultra-deep drawing, in which C and N in the steel are sufficiently fixed by carbonitride-forming elements, B is not added.
非常に苛酷なプレス成形後の二次加工の間に、脆性破断
により割れる現象が発生する問題がある。There is a problem that cracking occurs due to brittle fracture during the very severe secondary processing after press forming.
この脆性破断は、Ｍ中に固溶Ｃがないためフェライト粒
界へのＣの偏析がなく、そのためＰの粒界への偏析が促
進され、結果として粒界が脆化することによる。This brittle fracture is caused by the fact that since there is no solid solution C in M, there is no segregation of C to the ferrite grain boundaries, which promotes the segregation of P to the grain boundaries, resulting in embrittlement of the grain boundaries.
前記の特開昭５９−１９３２２１号公報および特開昭５
９−１４０３３３号公報が開示するＴｉ−Ｂ添加鋼およ
びＴｉ−Ｎｂ−Ｂ添加鋼では、添加したＢオ゛粒界に偏
析してＰの粒界への偏析を防止するため５苛酷なプレス
成形後の二次加工に際して二次加工割れが発生しにくい
ことが知られている。しかし、Ｂ添加量が多くなり過ぎ
ると、再結晶温度の上昇並びに多量の固溶Ｂの存在によ
り延性および深絞り性の劣化をきたす。また多量にＢを
含んだ鋼板は、表面処理２例えば、ユニクロメツキ処理
を施した場合には５色ムラの原因となるめっき不均一が
生ずる傾向があるし、亜鉛めっき処理を施した場合には
。The above-mentioned JP-A-59-193221 and JP-A-5
In the Ti-B-added steel and Ti-Nb-B-added steel disclosed in Publication No. 9-140333, 5 severe press forming is performed to prevent added B from segregating at grain boundaries and P from segregating at grain boundaries. It is known that secondary processing cracks are less likely to occur during subsequent secondary processing. However, if the amount of B added is too large, the recrystallization temperature increases and the presence of a large amount of solid solution B causes deterioration of ductility and deep drawability. In addition, when steel sheets containing a large amount of B are subjected to surface treatment 2, for example, unichrome plating, there is a tendency for uneven plating to occur, which causes five-color unevenness, and when subjected to zinc plating, .
めっきムラが生したりする欠点がある。逆に、Ｂ添加量
が少な過ぎると、耐・二次加工割れ住改善の充分な効果
が得られない。It has the disadvantage of causing uneven plating. On the other hand, if the amount of B added is too small, sufficient effects of improving resistance to secondary processing cracking and hardness cannot be obtained.
したがって、Ｂの添加により、延性および深絞り性を劣
化することな（、耐二次加工割れ性を効果的に改善する
ためには、Ｂ添加量を適正に制御する必要があるが、こ
れは、製鋼技術上、必ずしも容易なことではない。Therefore, in order to effectively improve secondary work cracking resistance without deteriorating ductility and deep drawability by adding B, it is necessary to appropriately control the amount of B added. , it is not necessarily an easy task in terms of steel manufacturing technology.
本発明は、Ｔｉ単独またはＴｉに加えＮｂおよびＣｒの
少なくとも一種を複合添加して鋼中のＣおよびＮを固定
した鋼板の耐二次加工割れ性を、Ｂ添加という手段によ
ることなく、改善することを目的とする。The present invention improves the secondary work cracking resistance of a steel plate in which C and N are fixed by adding Ti alone or in combination with at least one of Nb and Cr in addition to Ti, without adding B. The purpose is to
本発明によれば、Ｔｉ単独またはＴｉに加えＮｂおよび
Ｃｒの少なくとも一種を複合添加して鋼中のＣおよびＮ
を固定した冷延鋼板の耐二次加工割れ性は、当該鋼板の
両表層部に、しかるべき厚み。According to the present invention, C and N in steel are added by adding Ti alone or in combination with at least one of Nb and Cr in addition to Ti.
The secondary work cracking resistance of a cold-rolled steel sheet with fixed steel sheets is determined by applying an appropriate thickness to both surface layers of the steel sheet.
しかるべきＣ’／７４度の、非常に細粒な浸炭層を形成
することにより、改善できることが判った。It has been found that this can be improved by forming a very fine carburized layer with an appropriate C'/74 degrees.
かくして１本発明は、Ｔｉ単独またはＴｉに加えＮｂお
よびＣｒの少なくとも一種を複合添加して鋼中のＣおよ
びＮを固定した冷延鋼板であって１両表層部に浸炭層を
有し、全浸炭層厚み対＠仮の板厚の比が１７４〜１／１
２． 該浸炭層のＣ濃度平均が０．０２〜０．１０重量
％、該浸炭層のフェライト粒度Ｎｏ。Thus, the present invention provides a cold-rolled steel sheet in which C and N are fixed in the steel by adding Ti alone or in combination with at least one of Nb and Cr in addition to Ti, which has a carburized layer on the surface layer, and has a carburized layer on the entire surface layer. The ratio of carburized layer thickness to @temporary plate thickness is 174 to 1/1
2. The carburized layer has an average C concentration of 0.02 to 0.10% by weight, and a ferrite particle size No. of the carburized layer.
が９．５以上、そして板厚中心部のフェライト粒度Ｎｏ
、が６．０以上であることを特徴とする耐二次加工割れ
性の優れた深絞り用冷延鋼板を提供する。is 9.5 or more, and the ferrite grain size No. at the center of the plate thickness is
, is 6.0 or more, and provides a cold rolled steel sheet for deep drawing with excellent secondary work cracking resistance.
本発明は、また、真空脱ガス処理により溶製した鋼中の
ＣおよびＮを固定するに充分なＴｉ単独またはＴｉに加
え少なくとも一種を複合添加した極低炭素鋼を、常法に
従い、スラブとし、必要に応じスラブ手入れを行い、熱
間圧延し、酸洗いなどによりスケール除去後、トータル
圧延率６０％以上の冷間圧延を施し、オープンコイル焼
鈍を行うに際し、ｎ点を一７０〜０℃とする雰囲気ガス
条件で、焼鈍加熱温度を再結晶温度以上８３０℃以下。The present invention also provides a method for converting ultra-low carbon steel into a slab in accordance with a conventional method by adding enough Ti alone or in combination with at least one kind of Ti in addition to Ti to fix C and N in the steel melted by vacuum degassing treatment. , perform slab maintenance as necessary, hot-roll, remove scale by pickling, etc., then cold-roll at a total rolling reduction of 60% or more, and open coil annealing at -70 to 0°C. Under the atmospheric gas conditions, the annealing heating temperature is higher than the recrystallization temperature and lower than 830°C.
焼鈍時間を５時間以内として鋼板の両表層部に全浸炭層
厚み対板厚の比が１７４〜ｌ／１２の浸炭層を形成させ
ることを特徴とする耐二次加工割れ性の優れた濶絞り用
冷延鋼板の製造方法を提供する。Dry drawing with excellent secondary work cracking resistance characterized by forming a carburized layer on both surface parts of a steel plate with a ratio of total carburized layer thickness to plate thickness of 174 to 1/12 by setting an annealing time within 5 hours. Provided is a method for manufacturing cold-rolled steel sheets for industrial use.
耐二次加工割れ性のの改善という本発明の目的に対して
は１両浸炭層の合計厚み対鋼板の板厚の比が１７１２以
上であること、該浸炭層のＣ？Ｑ度平均が０．０２重量
％以上であること該浸炭層のフェライト粒度Ｎｏ、が９
．５以上であることおよび板厚中心部のフェライト粒度
Ｎｏ、が６．０以上であることが臨界的である。換言す
れば、これらの諸条件が満たされないと、耐二次加工割
れ性の実質的な改善が得られない。これに対し１両浸炭
層の合計厚み対鋼板の板厚の比の上限および浸炭層のＣ
濃度平均の上限は、それ程臨界的ではないが１両浸炭層
の合計厚み対鋼板の板厚の比が１／４を実質的に越えた
り浸炭層の０４度平均が０．１０重量％を実質的に越え
たりすると、製品の延性および深絞り性が劣化する傾向
があるので１両浸炭層の合計厚み対綱板の板厚の比をｌ
／１２〜１／４ そして浸炭層のＣ濃度平均を０．０２
〜０．１０重世％とした。For the purpose of the present invention, which is to improve secondary work cracking resistance, the ratio of the total thickness of both carburized layers to the thickness of the steel plate is 1712 or more, and the C? The average Q degree is 0.02% by weight or more. The ferrite grain size No. of the carburized layer is 9.
．． It is critical that the number is 5 or more and that the ferrite grain size No. at the center of the plate thickness is 6.0 or more. In other words, unless these conditions are met, no substantial improvement in secondary work cracking resistance can be obtained. In contrast, the upper limit of the ratio of the total thickness of one carburized layer to the thickness of the steel plate and the C of the carburized layer
The upper limit of the average concentration is not so critical, but if the ratio of the total thickness of one carburized layer to the thickness of the steel plate substantially exceeds 1/4 or the average of the carburized layers substantially exceeds 0.10% by weight. If the ductility and deep drawability of the product are exceeded, the ductility and deep drawability of the product tend to deteriorate.
/12 to 1/4 and the average C concentration in the carburized layer to 0.02
~0.10%.
本発明にしたがい、冷延鋼板の表層部に適正な浸炭層を
形成することによって、延性および深絞り性を劣化する
ことなく、耐二次加工割れ性を改善できることの正確な
作用機構は、まだ解明されていないが、第１に、浸炭に
より再結晶粒の成長が表層部で抑制され１表層部が非常
に細粒になること、そして第２に、浸炭した炭素のうち
Ｔ ｉ Ｃとして析出しなかった１〜２１）Ｐｌｎ程度
の炭素が粒界に偏析してＰの粒界への偏析を阻止するこ
とが耐二次加工割れ性を改善するものと考えられる。The exact mechanism by which secondary work cracking resistance can be improved without deteriorating ductility and deep drawability by forming an appropriate carburized layer on the surface layer of a cold-rolled steel sheet according to the present invention is still unknown. Although it is not clear yet, firstly, the growth of recrystallized grains is suppressed in the surface layer by carburizing, and the surface layer becomes very fine grains.Secondly, the carburized carbon precipitates as T i C. 1 to 21) It is considered that carbon of about Pln segregates at the grain boundaries and prevents the segregation of P to the grain boundaries, which improves the secondary work cracking resistance.
なお、本発明の冷延鋼板は、浸炭焼鈍後も、非時効性で
あることから１粒界に偏析しているｃｌは非常に少ない
といえる。In addition, since the cold rolled steel sheet of the present invention is non-aging even after carburizing and annealing, it can be said that there is very little Cl segregated at one grain boundary.
次に９本発明による耐二次加工割れ性の優れた深絞り用
冷延鋼板の製法について説明する。Next, a method for manufacturing a cold-rolled steel sheet for deep drawing with excellent resistance to secondary work cracking according to the present invention will be described.
本発明による耐二次加工割れ性の優れた深絞り用冷延鋼
板は、Ｔｉ単独またはＴｉに加えＮｂおよびＣｒの少な
くとも一種を複合添加して鋼中のＣおよびＮを固定した
鋼からなるトータル圧下率が６０％以上の冷延鋼板を、
所定の浸炭層が形成されるような条件下で、オープンコ
イル焼鈍することにより、好都合に製造できる。The cold-rolled steel sheet for deep drawing with excellent secondary work cracking resistance according to the present invention is a total steel sheet made of steel in which C and N in the steel are fixed by adding Ti alone or in combination with at least one of Nb and Cr in addition to Ti. Cold-rolled steel sheets with a rolling reduction of 60% or more,
It can be conveniently manufactured by open coil annealing under conditions such that a predetermined carburized layer is formed.
鋼の化学成分に関しては、鋼中のＣおよびＮがＴｉ単独
添加により、またはＴｉに加えＮｂおよびＣｒの少なく
とも一種の複合添加により固定されていること以外に特
別な限定はないが、高延性と深絞り性とを兼備した冷延
鋼板を得る目的からすれば、オープンコイル焼鈍前の冷
延鋼板の化学成分は、下記のような範囲とすることが好
ましい。Regarding the chemical composition of the steel, there is no particular limitation other than that C and N in the steel are fixed by the addition of Ti alone or by the combined addition of at least one of Nb and Cr in addition to Ti. For the purpose of obtaining a cold rolled steel sheet with good deep drawability, the chemical composition of the cold rolled steel sheet before open coil annealing is preferably within the following range.
Ｃは、その含有量が少ない程、冷延鋼板の延性が高くな
る。特に、Ｃ含有量が０．０１％よりも実質的に多いと
、炭窒化物形成元素を多く必要とし、加えて炭窒化物の
析出量の増大がプレス成形性を劣化する。他方、Ｃ含有
量をｏ、ｏｏｉ％よりも実質的に低くすることは、実用
規模の製鋼炉において非実際的である。よって、好まし
いＣ含有量は。The lower the content of C, the higher the ductility of the cold rolled steel sheet. In particular, when the C content is substantially higher than 0.01%, a large amount of carbonitride-forming elements are required, and in addition, an increase in the amount of carbonitride precipitation deteriorates press formability. On the other hand, reducing the C content substantially below o,ooi% is impractical in a utility-scale steelmaking furnace. Therefore, the preferable C content is as follows.
０．００１〜０．０１％である。It is 0.001 to 0.01%.
一般に、Ｓｉは溶鋼の脱酸を、そしてＭｎは熱間脆性の
防止をそれぞれ主目的として添加されるが。Generally, Si is added primarily to deoxidize molten steel, and Mn is added to prevent hot embrittlement.
ＳｉおよびＭｎはいずれも多量に添加しすぎると。If both Si and Mn are added in too large a quantity.
延性を劣化する。よって、ＳｉおよびＭｎは７通常の冷
延９′！Ｉ板に通常音まれる範囲の量、Ｓｉは、０．１
％以下、そしてＭｎは、０．５％以下であるのが好まし
い。Decreases ductility. Therefore, Si and Mn are 7 normal cold rolled 9'! The amount of sound normally heard on the I plate, Si, is 0.1
% or less, and Mn is preferably 0.5% or less.
Ａ１は、一般に、溶鋼の脱酸を目的として添加されるが
、その量が、鋼中のｓｏｌ、Ａｌ１として０．０１％よ
りも実質的に少ない量では、脱酸の目的が充分には達成
されない、一方＋ｓｏ１．Ａｌが０．１０％を越えるに
つれ、脱酸効果は飽和するとともに、非金属介在物が増
加して表面疵の原因になる。よって、ｓｏｌ、Ａｊ！は
、 ０．０１〜０．１０％であるのが好ましい。A1 is generally added for the purpose of deoxidizing molten steel, but if the amount is substantially less than 0.01% as sol and Al1 in steel, the purpose of deoxidizing is not fully achieved. is not done, while +so1. As Al exceeds 0.10%, the deoxidizing effect becomes saturated and nonmetallic inclusions increase, causing surface flaws. Therefore, sol, Aj! is preferably 0.01 to 0.10%.
Ｃｒは２Ｔｉと、またはＴｉおよびＮｂと、複合添加す
ることによって、深絞り性および張り出し性を向上する
効果を発揮する。この目的のためには。When Cr is added in combination with 2Ti or with Ti and Nb, it exhibits the effect of improving deep drawability and stretchability. For this purpose.
０．０６％以上のＣｒが必要である。だが、 ０．２０
％を越えるような量のＣｒを添加しても、この効果が飽
和し、製造原価を高めるだけである。それ故。Cr of 0.06% or more is required. However, 0.20
Even if Cr is added in an amount exceeding 10%, this effect will be saturated and the manufacturing cost will only increase. Therefore.
０．０６〜０．２０％の範囲で、必要に応じ、Ｃｒを含
有させるのが好ましい。It is preferable to contain Cr in the range of 0.06 to 0.20%, if necessary.
Ｐは、あまり多く添加すると、降伏強度および引張強度
を高めるようになり、また、Ｔｉ界への偏析量が多くな
って、二次加工割れが促進される。If too much P is added, the yield strength and tensile strength will increase, and the amount of segregation in Ti boundaries will increase, promoting secondary work cracking.
よって、Ｐ含［１の上限は、 ０．０３％とするのが好
ましい。Therefore, the upper limit of P-containing [1 is preferably 0.03%.
Ｎ、Ｓおよび０は、Ｔ１と強く結合してそれぞれ窒化物
、硫化物および酸化物を形成するので。Since N, S and 0 combine strongly with T1 to form nitrides, sulfides and oxides, respectively.
それらの含有量が多くなり過ぎると、Ｃを鋼中で固定す
るのに必要なＴｉ添加量が増加するのみならず、プレス
成形性および表面性状の劣化を招く不利がある。それ故
、Ｎは、０．００７％以下、Ｓは。If their content becomes too large, not only will the amount of Ti added required to fix C in the steel increase, but there will also be a disadvantage of deterioration of press formability and surface properties. Therefore, N is 0.007% or less, and S is 0.007% or less.
０．０１５％以下そしてＯは、０．０１％以下とするの
が好ましい。The content of O is preferably 0.015% or less, and O is preferably 0.01% or less.
Ｔｉは、ＣおよびＮを固定することによって冷延鋼板の
非時効性を確保するとともに、生成したＴｉＣが深絞り
性の向上にを効な（１１１１面方位０再結晶粒集合ｍ織
を発達させる。したがって１本発明の目的に対しては５
窒化物、硫化物および酸化物としてのＴｉｉを全Ｔｉ量
から差し引いた有効Ｔ ｉ ｉｆｆが４ＸＣ％以上であ
ることが必要である。Ti secures the anti-aging properties of cold-rolled steel sheets by fixing C and N, and the generated TiC is effective in improving deep drawability (developing a recrystallized grain aggregation structure with 1111 plane orientation 0). .Therefore, 1.5 for the purpose of the present invention.
It is necessary that the effective T i iff, which is obtained by subtracting Tii as nitrides, sulfides, and oxides from the total Ti amount, is 4XC% or more.
だが、Ｔｉ１ｌが０．４０％を実質的に越えると、その
効果が飽和するばかりでなく１粒内強度を増すため耐二
次加工割れ性の劣化を促進する。よって。However, when Ti1l substantially exceeds 0.40%, not only does this effect become saturated, but also the intra-grain strength increases, which promotes deterioration of secondary work cracking resistance. Therefore.
Ｔｉ量の上限は、 ０．４０％とするのが好ましい。The upper limit of the amount of Ti is preferably 0.40%.
Ｎｂは、 ０．０３％以上含有させると、冷延鋼板のｒ
値の面内異方性を改善する効果があるが、過剰のＮｂは
延性の劣化を招く。よって、Ｎｂは、必要に応じて０．
０３〜０．１０％の範囲で添加するのが好ましい。When Nb is contained at 0.03% or more, the r
Although it has the effect of improving the in-plane anisotropy of the value, excessive Nb causes deterioration of ductility. Therefore, Nb may be adjusted to 0.
It is preferable to add it in a range of 0.03 to 0.10%.
本発明の冷延鋼板の製造にあたっては、常法どうり、製
鋼炉で鋼を溶製するが、造塊または連続鋳造前に、真空
脱ガス処理を行うのが好ましい。In producing the cold-rolled steel sheet of the present invention, steel is melted in a steelmaking furnace as usual, but it is preferable to perform vacuum degassing treatment before ingot formation or continuous casting.
真空脱ガス処理に際しては、脱酸の目的で八〇を添加す
ることができる。During vacuum degassing treatment, 80% can be added for the purpose of deoxidation.
真空脱ガス処理後１造塊および分塊圧延によってまたは
連続鋳造によってスラブを製造し、必要に応じてスラブ
手入れを行った後、熱間圧延を行う。別法としては、連
続鋳造後、一旦冷鋳片としたあと再加熱して熱間圧延を
行うか、または熱鋳片のまま加熱炉に装入して熱間圧延
を行ってもよい。After vacuum degassing treatment, a slab is manufactured by ingot formation and blooming rolling or by continuous casting, and after performing slab care as necessary, hot rolling is performed. Alternatively, after continuous casting, the hot cast slab may be once made into a cold slab and then reheated and hot rolled, or the hot slab may be charged into a heating furnace as it is and hot rolled.
熱間圧延の実施に際しては、深絞り性向上の観点から、
熱延仕上温度をＡｒ３点以上にするのが好ましい。また
、熱延巻取温度は、 ６００〜１５０℃の範囲とするの
が好ましい。When carrying out hot rolling, from the perspective of improving deep drawability,
It is preferable to set the hot rolling finishing temperature to Ar3 or higher. Further, the hot rolling coiling temperature is preferably in the range of 600 to 150°C.
熱延鋼板は、酸洗後３冷間圧延に付すが、この冷間圧延
は、深絞り性に存利な（１１１１面方位０再合Ｍｉ ４
８を発達させる上で、 ６０％以上のトータル冷延率で
行うことが必要である。After pickling, the hot-rolled steel sheet is cold-rolled three times.
8, it is necessary to conduct the rolling with a total cold rolling rate of 60% or more.
かくして得られた冷延鋼板の両表層部に、オープンコイ
ル焼鈍により、所定の浸炭層を形成するのであるが、そ
の際、諸条件５特に焼鈍温度、均熱時間および焼鈍雰囲
気を、所定の浸炭層が形成されるよう、以下において説
明する如（制御することが必要である。A predetermined carburized layer is formed on both surface layers of the cold-rolled steel sheet thus obtained by open coil annealing. It is necessary to control the formation of the layers as described below.
焼鈍温度は、再結晶温度以上（好ましくは約７３０℃以
上）８３０ ℃以下範囲の温度とする。８３０℃よりも
実質的に高い温度で焼鈍を行うと、フェライト粒が粗大
化し、耐二次加工割れ性のよい製品が得られない。焼鈍
時間は、大延の場合５時間以内とするのがよい。不当に
長時間焼鈍を行うと浸炭が過度になり、その結果浸炭層
の厚みおよび／または浸炭層のＣ濃度が過大になって、
得られる製品の延性お深絞り性が劣化する傾向がある。The annealing temperature is in the range of not less than the recrystallization temperature (preferably not less than about 730°C) and not more than 830°C. If annealing is performed at a temperature substantially higher than 830° C., the ferrite grains will become coarse, making it impossible to obtain a product with good resistance to secondary work cracking. The annealing time is preferably within 5 hours in the case of Ohnobe. Annealing for an unreasonably long time will result in excessive carburization, resulting in excessive carburized layer thickness and/or excessive C concentration in the carburized layer.
The ductility and deep drawability of the resulting product tend to deteriorate.
雰囲気ガスは、ＨＮＸガス（Ｈｚ：３〜ｌＯ％、Ｎ２：
９７〜９０％、Ｃｏｔ：０．２％以下、ｃｏ：ｏ、２％
以下）で置換した後、高純度のＡＸガス（Ｈｚニア５％
。The atmospheric gas was HNX gas (Hz: 3~1O%, N2:
97-90%, Cot: 0.2% or less, co:o, 2%
After replacing with high purity AX gas (Hz near 5%)
.
ＮＺ＋２５％）とするのがよい。鋼板の表層部−・の浸
炭は、雰囲気中に含有される５００〜１５００ｐｐｍ程
度のＣＯにより進行する。そのＣＯ源としては、 Ｈ
ＮＸガス中に存在する２０００ｐｐｍ程度のＣＯが、パ
ージ後ＡＸガス切換後も残存する場合と、焼鈍炉内に不
可避的に存在する塵埃や油分がＣＯ源となる場合とがあ
る。もっとも、パージガスとしてＨＮＸガスを使用する
のは、全く経済的な理由によるものであり、Ｎｚガスや
ＡＸガスをパージガスとして使用しても、均熱中のＡＸ
ガス雰囲気中には、５００〜１２００ｐｐｍ程度のＣＯ
が存在するため。NZ+25%). Carburization of the surface layer of the steel plate progresses due to approximately 500 to 1500 ppm of CO contained in the atmosphere. The CO source is H
There are cases where about 2000 ppm of CO present in the NX gas remains even after switching to the AX gas after purging, and cases where dust and oil inevitably present in the annealing furnace become the CO source. However, the use of HNX gas as a purge gas is purely for economic reasons, and even if Nz gas or AX gas is used as a purge gas, AX gas during soaking will
There is about 500 to 1200 ppm of CO in the gas atmosphere.
Because there is.
浸炭を促進させるのに何等問題でない。There is no problem in promoting carburization.
雰囲気の露点は、−７０〜０℃の範囲で制御する必要が
ある。露点が０℃を実質的に越えると、雰囲気中にＣＯ
が５００〜１５００ｐｐｍ存在しても、雰囲気のもつ浸
炭力が弱いため ７ｉ１ｉ定の浸炭層が形成されないこ
とがしばしばある。一方、露点が低い程。The dew point of the atmosphere needs to be controlled within the range of -70 to 0°C. When the dew point substantially exceeds 0°C, CO is present in the atmosphere.
Even if 500 to 1500 ppm of carbon dioxide is present, a uniform carburized layer is often not formed because the carburizing power of the atmosphere is weak. On the other hand, the lower the dew point.
雰囲気のもつ浸炭力は強くなるが、商業的規模では一７
０℃が限度であり、ｎ点を一７０℃よりも低く制御する
ことは経済的に得策でない。The carburizing power of the atmosphere becomes stronger, but on a commercial scale it is
The limit is 0°C, and it is not economically advisable to control the n point below -70°C.
付図を参照するに、第１図は本発明による冷延鋼板の概
略断面図である。第１図に見られる如く。Referring to the accompanying drawings, FIG. 1 is a schematic cross-sectional view of a cold-rolled steel sheet according to the present invention. As seen in Figure 1.
本発明の冷延鋼板は、一方の表層側に厚さが１．の浸炭
層を、そして他方の表層側に厚さがｔ２の浸炭層を有す
る。冷延鋼板の板厚をｔｏとすると、全浸炭層厚み対板
厚の比 ｔｃ ”（ｔ＋ ” ｔｉ ）ハ。 は１／
１２〜１／４ の範囲である。The cold rolled steel sheet of the present invention has a thickness of 1.5 mm on one surface layer side. and a carburized layer with a thickness of t2 on the other surface side. When the thickness of the cold-rolled steel plate is to, the ratio of the total carburized layer thickness to the plate thickness is tc ''(t+''ti)c. is 1/
It is in the range of 12 to 1/4.
第２図は後記の試験ＮＯ１２による本発明の冷延鋼板の
一方の表層側の板厚方向断面を示す金属組織写真（倍率
：１００倍）であるが、この例の場合。FIG. 2 is a metallographic photograph (magnification: 100 times) showing a cross-section in the thickness direction of one surface layer side of a cold rolled steel sheet of the present invention according to Test No. 12 described later, in the case of this example.
金属組織写真から求めた同写真に示した表層側の浸炭層
の厚み１．は１００ μであった。The thickness of the carburized layer on the surface layer shown in the photo, determined from the metallographic photo: 1. was 100μ.
第３図は同じく後記の試験Ｎ００２による本発明の冷延
鋼板の一方の表層側の板厚方向断面のＥＰＭＡによるＣ
濃度の線分析結果を示す図である。FIG. 3 shows EPMA of a cross section in the thickness direction of one surface layer of a cold-rolled steel sheet of the present invention according to Test No. 002, which will also be described later.
FIG. 3 is a diagram showing the results of line analysis of concentration.
同図から求めた浸炭層の厚みは、第２図の金属組織写真
から求めた値と一致する。試験ＮＯ１２の場合、ｔ＋
＝ ｔｚ ＝ １００μ＋ ｔｏ＝１．２ ｍｍであっ
たことから、 １ｃ＝（１，＋ １２）ハ、 ＝ １
／６ と算出された。The thickness of the carburized layer determined from the same figure matches the value determined from the metallographic photograph of FIG. 2. In the case of test No. 12, t+
= tz = 100μ+ to = 1.2 mm, so 1c = (1, + 12) = 1
/6 was calculated.
浸炭層のＣ’ＩＮ度の平均は、このようにして求めた１
ｃ と、浸炭後の全板厚平均Ｃ濃度（ｙ％）および浸炭
前の全板厚平均Ｃ濃度（ｙ％）とから次式浸炭層のＣ濃
度の平均
＝ Ｃｘ％−（１−ｔｃ）ｙ％） ／ｌｃにしたがい好
都合に算出できるが、この値は。The average C'IN degree of the carburized layer is 1
c, the average C concentration of the entire plate thickness after carburizing (y%), and the average C concentration of the entire plate thickness before carburizing (y%), the following formula is used: Average C concentration of the carburized layer = Cx%-(1-tc) This value can be conveniently calculated according to y%) /lc.
０．０２〜０．１０％の範囲内である。It is within the range of 0.02 to 0.10%.
また、浸炭層のフェライト粒度Ｎｏ、は、９．５以上で
あり、板厚中心部のフェライト粒度Ｎｏ、 は。Further, the ferrite grain size No. of the carburized layer is 9.5 or more, and the ferrite grain size No. at the center of the plate thickness is.
９．５以上である。It is 9.5 or more.
実施例 第１表 供試鋼の化学成分 １８０トン転炉および脱ガス処理設備によって。Example Table 1 Chemical composition of test steel With a 180 ton converter and degassing equipment.
第１表に示す化学成分値の鋼を成分調整し、各溶鋼を連
続鋳造によってスラブとなし、各スラブから加熱温度１
２５０〜１２７０℃、熱延仕上温度９００〜９３０℃、
熱延巻取温度７００〜７３０℃の熱延条件で熱延コイル
を得、酸洗のあと、第２表に示す冷延率で板厚１．２１
まで冷間圧延した。各コイルに、第２表に示す、焼鈍温
度７５０〜８５０’Ｃ，焼鈍時間１〜６時間、均熱時の
露点−５０〜＋５０℃の条件で、ＨＮＸガスによる置換
後、ＡＸガスを雰囲気としてオープンコイル焼鈍を施し
、鋼板の両表層部に、細粒のフェライトからなる浸炭層
を形成した。The composition of steel with the chemical composition values shown in Table 1 is adjusted, each molten steel is made into slabs by continuous casting, and each slab is heated to a temperature of 1
250-1270℃, hot rolling finishing temperature 900-930℃,
A hot-rolled coil was obtained under hot-rolling conditions with a hot-rolling coiling temperature of 700 to 730°C, and after pickling, a plate thickness of 1.21 was obtained at the cold rolling rate shown in Table 2.
Cold rolled to Each coil was replaced with HNX gas under the conditions shown in Table 2, annealing temperature 750 to 850'C, annealing time 1 to 6 hours, dew point during soaking -50 to +50℃, and AX gas as an atmosphere. Open coil annealing was performed to form a carburized layer consisting of fine grained ferrite on both surface layers of the steel plate.
各試験で得た冷延鋼板のａ械的性質および耐二次加工割
れ限界温度を第２表に示す。Table 2 shows the mechanical properties and secondary processing cracking resistance limit temperature of the cold rolled steel sheets obtained in each test.
耐二次加工割れ性試験では、試験機を９０ｍｍφにブラ
ンク後、第１次絞り５０φ１第２次絞り４０φ。In the secondary work cracking resistance test, the testing machine was blanked to 90 mmφ, and the first drawing was 50φ and the second drawing was 40φ.
そして第３次絞り３３φの３段絞り（総絞り比＝２．７
）で、カップ成形し、得られたカップを４０ｍｍの高さ
にトリムした後、各試験温度に調整した冷媒中にカップ
を置いて、頂角６０°の円錐コーン形のポンチを押し込
み、縦割れと称される脆性破壊の発生しない下限温度を
測定し、この温度を耐二次加工割れ限界温度とした。耐
二次加工割れ限界温度が一５０℃よりも実質的に高いも
のは、耐二次加工割れ性が不良であるとしなければなら
ない。And 3-stage aperture with 33φ tertiary aperture (total aperture ratio = 2.7
), and after trimming the obtained cup to a height of 40 mm, place the cup in a refrigerant adjusted to each test temperature, and press a conical cone-shaped punch with an apex angle of 60° to remove vertical cracks. The lower limit temperature at which brittle fracture does not occur was measured, and this temperature was defined as the secondary processing cracking resistance limit temperature. If the secondary work cracking resistance limit temperature is substantially higher than 150°C, the secondary work cracking resistance must be considered to be poor.
深絞り性の評価としては、全伸び（Ｔ、ＥｔＭが４５％
以上で且つＹ値が１，８以上であれば、深絞り性は良好
であるといえる。これらいずれかの条件が満たされない
なら、深絞り性は不良であるとしなければならない。For evaluation of deep drawability, total elongation (T, EtM is 45%)
If it is above and the Y value is 1.8 or more, it can be said that the deep drawability is good. If any of these conditions are not met, the deep drawability must be considered poor.
第２表から明らかなように、Ｔｉ添加鋼の供試鋼Ａで７
本発明例の試験Ｎｏ、 ２のものは、全伸びが４８．３
％と高いだけでなく、Ｙ値が２，１７と高く。As is clear from Table 2, 7
Test No. 2 of the present invention example had a total elongation of 48.3.
Not only is it high at %, but the Y value is also high at 2.17.
且つ耐二次加工割れ限界温度も一７０℃と低く１延性、
深絞り性および耐二次加工割れ性が極めて良好である。In addition, the limit temperature for secondary processing cracking is as low as -70°C, and the ductility is low.
Extremely good deep drawability and secondary work cracking resistance.
これに対し、全浸炭層厚み対板厚比が１／２ と本発明
の範囲外である試験Ｎｏ、１（比較例）のものは、耐二
次゛加工割れ性は良いが、全伸びが３６．３％と、Ｔｉ
添加鋼としては、非常に低い。またＹ値により示される
深絞り性も不満足である。On the other hand, Test No. 1 (comparative example), in which the total carburized layer thickness to plate thickness ratio is 1/2, which is outside the scope of the present invention, has good secondary work cracking resistance, but has low total elongation. 36.3%, Ti
This is extremely low for additive steel. Further, the deep drawability indicated by the Y value is also unsatisfactory.
雰囲気露点がそれぞれ＋２０℃および＋５０℃と高い試
験Ｎｏｓ、 ３および４（比較例）のものは、浸炭層が
形成されず、耐二次加工割れ性が劣る。Test Nos. 3 and 4 (comparative examples) with high atmospheric dew points of +20° C. and +50° C., respectively, did not form a carburized layer and had poor secondary work cracking resistance.
Ｔｉ−Ｎｂ−Ｃｒ添加鋼の供試鋼Ｂで１本発明例の試験
Ｎｏｓ、 ６． ７． ８ および１３のものは、
全伸びが４９．３〜５０．３％と高＜、Ｔ値も２．０５
〜２．１８と良好であり、さらに５耐二次加工割れ限界
温度は。Test No. 1 of the present invention example for test steel B of Ti-Nb-Cr added steel, 6. 7. 8 and 13 are
Total elongation is high at 49.3-50.3%, T value is also 2.05
~2.18, which is good, and furthermore, the secondary processing cracking limit temperature is 5.
−５０〜−７０℃と低く、耐二次加工割れ性が優れてい
る。試験Ｎｏｓ、１０および１１のもの（比較例）は。It has a low temperature of -50 to -70°C, and has excellent secondary processing cracking resistance. Test Nos. 10 and 11 (comparative examples).
細粒なフェライトからなる浸炭層が形成されていないた
め、耐二次加工割れ限界温度が−３０〜−４０℃と比較
的高く、耐二次加工割れ性が劣っている。Since a carburized layer consisting of fine-grained ferrite is not formed, the secondary work cracking resistance limit temperature is relatively high at -30 to -40°C, and the secondary work cracking resistance is poor.
また、試験Ｎｏ、１２ （比較例）のものは、焼鈍温度
が高過ぎたため、板厚中心部のフェライト粒度Ｎｏ。In addition, in test No. 12 (comparative example), the annealing temperature was too high, so the ferrite grain size No. at the center of the plate thickness.
が４．０と本発明の範囲外であり、全伸びが比較的低く
、耐二次加工割れ限界温度は一１０℃と耐二次加工割れ
性が非常に劣っている。試験Ｎｏｓ、 １４〜１６は、
熱延板の厚さを変えることにより、冷延率の影響を調べ
たものであるが、冷延率が５０％と低い試験Ｎｏ、 １
４（比較例）では、Ｙ値が１．５３と低く目標とする深
絞り性が得られない。これに対し。is 4.0, which is outside the range of the present invention, the total elongation is relatively low, and the secondary work cracking resistance limit temperature is -10°C, which is very poor in secondary work cracking resistance. Exam Nos. 14-16 are
The effect of the cold rolling rate was investigated by changing the thickness of the hot rolled sheet, and test No. 1 had a low cold rolling rate of 50%.
In No. 4 (comparative example), the Y value was as low as 1.53, and the target deep drawability could not be obtained. Against this.
本発明例である試験Ｎｏｓ、 １５および１Ｇでは、目
標とする特性が得られている。In tests Nos. 15 and 1G, which are examples of the present invention, the target characteristics were obtained.
本発明にしたがい、Ｔｉ単独を、またはＴｉに加えＮｂ
およびＣｒの少なくとも一種を複合添加して鋼中のＣお
よびＮを固定した冷延鋼板をオープンコイル焼鈍するに
際して、鋼板中心部のフェライト粒度を適正に制御する
とともに、鋼板の両表層部に適正な浸炭層を形成するな
ら、耐二次加工割れ性の優れた濶絞り用冷延鋼板を得る
ことが可能である。According to the invention, Ti alone or in addition to Ti
When open-coil annealing a cold-rolled steel sheet in which C and N in the steel have been fixed by adding at least one of Cr and Cr, the ferrite grain size in the center of the steel sheet is appropriately controlled, and the If a carburized layer is formed, it is possible to obtain a cold-rolled steel sheet for water drawing that has excellent secondary work cracking resistance.
第１図は本発明による冷延鋼板の概略断面図。
第２図は試験Ｎｏ、 ２による本発明の冷延鋼板の一
方の表層側の板厚方向断面の金属組織を示すａ微鏡写真
（倍率：１００倍）、そして第３図は同じく試験Ｎｏ、
２による本発明の冷延鋼板の一方の表層側の板厚方
向断面のＥＰＭＡによるｃ？ｉ１度の線分析結果を示す
図である。FIG. 1 is a schematic cross-sectional view of a cold-rolled steel sheet according to the present invention. Figure 2 is a micrograph (magnification: 100x) showing the metallographic structure of the cross-section in the thickness direction of one surface layer of the cold rolled steel sheet of the present invention according to Test No. 2, and Figure 3 is the same as Test No. 2.
c? by EPMA of the thickness direction cross section of one surface layer side of the cold rolled steel sheet of the present invention according to No. 2. It is a figure which shows the line analysis result of i1 degrees.
Claims (2)
なくとも一種を複合添加して鋼中のＣおよびＮを固定し
た冷延鋼板であって、両表層部に浸炭層を有し、全浸炭
層厚み対板厚の比が１／４〜１／１２、該浸炭層のＣ濃
度平均が０．０２〜０．１０重量％、該浸炭層のフェラ
イト粒度Ｎｏ．が９．５以上、そして板厚中心部のフェ
ライト粒度Ｎｏ．が６．０以上であることを特徴とする
耐二次加工割れ性の優れた深絞り用冷延鋼板。(1) A cold-rolled steel sheet in which C and N in the steel are fixed by adding Ti alone or in combination with at least one of Nb and Cr in addition to Ti, which has a carburized layer on both surface parts, and has a carburized layer in all the carburized layers. The ratio of thickness to plate thickness is 1/4 to 1/12, the average C concentration of the carburized layer is 0.02 to 0.10% by weight, and the ferrite grain size of the carburized layer is No. is 9.5 or more, and the ferrite grain size No. at the center of the plate thickness is 9.5 or more. A cold-rolled steel sheet for deep drawing with excellent secondary work cracking resistance, characterized in that the is 6.0 or more.
Ｎを固定するに充分なＴｉ単独またはＴｉに加えＮｂお
よびＣｒの少なくとも一種を複合添加した極低炭素鋼を
、常法に従い、スラブとし、熱間圧延し、スケール除去
後、トータル圧延率６０％以上の冷間圧延を施し、オー
プンコイル焼鈍を行うに際し、露点を−７０〜０℃とす
る雰囲気ガス条件で、焼鈍加熱温度を再結晶温度以上８
３０℃以下、焼鈍時間を５時間以内として鋼板の両表層
部に全浸炭層厚み対板厚の比が１／４〜１／１２の浸炭
層を形成させることを特徴とする耐二次加工割れ性の優
れた深絞り用冷延鋼板の製造方法。(2) Ultra-low carbon steel containing enough Ti alone or a combination of at least one of Nb and Cr in addition to Ti to fix C and N in the steel produced by vacuum degassing treatment, according to a conventional method, A slab is formed into a slab, hot rolled, scale removed, cold rolled with a total rolling reduction of 60% or more, and open coil annealed at an annealing heating temperature under atmospheric gas conditions with a dew point of -70 to 0°C. Recrystallization temperature or higher8
Secondary work cracking resistance characterized by forming a carburized layer on both surface parts of a steel plate with a ratio of 1/4 to 1/12 of the total carburized layer thickness to the plate thickness at 30°C or less and for annealing time of 5 hours or less. A method for manufacturing cold-rolled steel sheets for deep drawing with excellent properties.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP61183051A JPH0647706B2 (en) | 1986-08-04 | 1986-08-04 | Cold-rolled steel sheet for deep drawing with excellent secondary work cracking resistance and method for producing the same |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP61183051A JPH0647706B2 (en) | 1986-08-04 | 1986-08-04 | Cold-rolled steel sheet for deep drawing with excellent secondary work cracking resistance and method for producing the same |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS6338556A true JPS6338556A (en) | 1988-02-19 |
| JPH0647706B2 JPH0647706B2 (en) | 1994-06-22 |
Family
ID=16128877
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP61183051A Expired - Lifetime JPH0647706B2 (en) | 1986-08-04 | 1986-08-04 | Cold-rolled steel sheet for deep drawing with excellent secondary work cracking resistance and method for producing the same |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0647706B2 (en) |
Cited By (13)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0372032A (en) * | 1989-08-09 | 1991-03-27 | Kobe Steel Ltd | Production of sheet steel |
| EP0421087A2 (en) * | 1989-08-09 | 1991-04-10 | KABUSHIKI KAISHA KOBE SEIKO SHO also known as Kobe Steel Ltd. | Method of manufacturing a steel sheet |
| JPH0394020A (en) * | 1989-09-05 | 1991-04-18 | Kobe Steel Ltd | Production of cold rolled steel sheet for deep drawing excellent in resistance to secondary working brittleness |
| JPH0394021A (en) * | 1989-09-05 | 1991-04-18 | Kobe Steel Ltd | Production of cold rolled steel sheet excellent in deep drawability and resistance to secondary working brittleness |
| JPH0394022A (en) * | 1989-09-05 | 1991-04-18 | Kobe Steel Ltd | Production of hot rolled steel plate for deep drawing excellent in resistance to secondary working brittleness |
| JPH03150318A (en) * | 1989-11-03 | 1991-06-26 | Kobe Steel Ltd | Manufacture of cold rolled steel sheet for deep drawing having excellent baking hardenability in paint |
| JPH03150317A (en) * | 1989-11-02 | 1991-06-26 | Kobe Steel Ltd | Manufacture of hot dip galvanized cold rolled steel sheet for deep drawing having excellent brittlement resistance in secondary working |
| JPH03199343A (en) * | 1989-12-28 | 1991-08-30 | Kawasaki Steel Corp | Cold rolled steel sheet for press working having extremely good chemical conversion treatability, weldability, punchability and slidability |
| EP0444967A2 (en) * | 1990-03-02 | 1991-09-04 | Kabushiki Kaisha Kobe Seiko Sho | Cold-rolled steel sheets or hot-dip galvanized cold rolled steel sheets for deep drawing |
| JPH04272143A (en) * | 1991-02-28 | 1992-09-28 | Nippon Steel Corp | Manufacture of cold rolled steel sheet for deep drawing excellent in dent resistance |
| JPH10168544A (en) * | 1996-12-10 | 1998-06-23 | Nkk Corp | Cold rolled steel sheet excellent in blanking property and its production |
| US5831251A (en) * | 1996-02-06 | 1998-11-03 | Denso Corporation | Heater unit having increased dielectric strength |
| EP1484419A2 (en) * | 2003-06-05 | 2004-12-08 | ThyssenKrupp Stahl AG | Procedure for manufacturing carburized steel strips |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5967319A (en) * | 1982-10-08 | 1984-04-17 | Nippon Steel Corp | Manufacture of steel plate for extremely deep drawing |
| JPS59140333A (en) * | 1983-01-28 | 1984-08-11 | Nippon Steel Corp | Manufacture of cold rolled steel sheet for deep drawing with superior secondary workability and surface treatability |
| JPS59193221A (en) * | 1983-04-15 | 1984-11-01 | Nippon Steel Corp | Rreparation of cold rolled steel plate used in ultra-deep drawing having extremely excellent secondary processability |
| JPS60149729A (en) * | 1984-01-11 | 1985-08-07 | Kawasaki Steel Corp | Production of cold rolled steel sheet for press forming |
-
1986
- 1986-08-04 JP JP61183051A patent/JPH0647706B2/en not_active Expired - Lifetime
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5967319A (en) * | 1982-10-08 | 1984-04-17 | Nippon Steel Corp | Manufacture of steel plate for extremely deep drawing |
| JPS59140333A (en) * | 1983-01-28 | 1984-08-11 | Nippon Steel Corp | Manufacture of cold rolled steel sheet for deep drawing with superior secondary workability and surface treatability |
| JPS59193221A (en) * | 1983-04-15 | 1984-11-01 | Nippon Steel Corp | Rreparation of cold rolled steel plate used in ultra-deep drawing having extremely excellent secondary processability |
| JPS60149729A (en) * | 1984-01-11 | 1985-08-07 | Kawasaki Steel Corp | Production of cold rolled steel sheet for press forming |
Cited By (20)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0421087A2 (en) * | 1989-08-09 | 1991-04-10 | KABUSHIKI KAISHA KOBE SEIKO SHO also known as Kobe Steel Ltd. | Method of manufacturing a steel sheet |
| JPH0372032A (en) * | 1989-08-09 | 1991-03-27 | Kobe Steel Ltd | Production of sheet steel |
| JPH0784622B2 (en) * | 1989-09-05 | 1995-09-13 | 株式会社神戸製鋼所 | Method for producing hot-rolled steel sheet for deep drawing excellent in secondary processing brittleness resistance |
| JPH0394020A (en) * | 1989-09-05 | 1991-04-18 | Kobe Steel Ltd | Production of cold rolled steel sheet for deep drawing excellent in resistance to secondary working brittleness |
| JPH0394021A (en) * | 1989-09-05 | 1991-04-18 | Kobe Steel Ltd | Production of cold rolled steel sheet excellent in deep drawability and resistance to secondary working brittleness |
| JPH0394022A (en) * | 1989-09-05 | 1991-04-18 | Kobe Steel Ltd | Production of hot rolled steel plate for deep drawing excellent in resistance to secondary working brittleness |
| JPH0784619B2 (en) * | 1989-09-05 | 1995-09-13 | 株式会社神戸製鋼所 | Method for producing cold-rolled steel sheet excellent in deep drawability and resistance to secondary work brittleness |
| JPH0784618B2 (en) * | 1989-09-05 | 1995-09-13 | 株式会社神戸製鋼所 | Method for producing cold-rolled steel sheet for deep drawing excellent in secondary processing brittleness resistance |
| JPH03150317A (en) * | 1989-11-02 | 1991-06-26 | Kobe Steel Ltd | Manufacture of hot dip galvanized cold rolled steel sheet for deep drawing having excellent brittlement resistance in secondary working |
| JPH0784620B2 (en) * | 1989-11-02 | 1995-09-13 | 株式会社神戸製鋼所 | Method for producing hot-dip galvanized cold-rolled steel sheet for deep drawing excellent in secondary processing brittleness resistance |
| JPH03150318A (en) * | 1989-11-03 | 1991-06-26 | Kobe Steel Ltd | Manufacture of cold rolled steel sheet for deep drawing having excellent baking hardenability in paint |
| JPH0784621B2 (en) * | 1989-11-03 | 1995-09-13 | 株式会社神戸製鋼所 | Method for manufacturing cold-rolled steel sheet for deep drawing with excellent bake hardenability |
| JPH03199343A (en) * | 1989-12-28 | 1991-08-30 | Kawasaki Steel Corp | Cold rolled steel sheet for press working having extremely good chemical conversion treatability, weldability, punchability and slidability |
| EP0444967A2 (en) * | 1990-03-02 | 1991-09-04 | Kabushiki Kaisha Kobe Seiko Sho | Cold-rolled steel sheets or hot-dip galvanized cold rolled steel sheets for deep drawing |
| JPH04272143A (en) * | 1991-02-28 | 1992-09-28 | Nippon Steel Corp | Manufacture of cold rolled steel sheet for deep drawing excellent in dent resistance |
| JP2542535B2 (en) * | 1991-02-28 | 1996-10-09 | 新日本製鐵株式会社 | Manufacturing method of cold-rolled steel sheet for deep drawing with excellent dent resistance |
| US5831251A (en) * | 1996-02-06 | 1998-11-03 | Denso Corporation | Heater unit having increased dielectric strength |
| JPH10168544A (en) * | 1996-12-10 | 1998-06-23 | Nkk Corp | Cold rolled steel sheet excellent in blanking property and its production |
| EP1484419A2 (en) * | 2003-06-05 | 2004-12-08 | ThyssenKrupp Stahl AG | Procedure for manufacturing carburized steel strips |
| EP1484419A3 (en) * | 2003-06-05 | 2005-10-19 | ThyssenKrupp Stahl AG | Procedure for manufacturing carburized steel strips |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0647706B2 (en) | 1994-06-22 |
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