JPH0681081A - Cold roller steel sheet and galvanized cold rolled steel sheet combining excellent baking hardenability and cold nonaging property as well and production thereof - Google Patents
Cold roller steel sheet and galvanized cold rolled steel sheet combining excellent baking hardenability and cold nonaging property as well and production thereofInfo
- Publication number
- JPH0681081A JPH0681081A JP4232300A JP23230092A JPH0681081A JP H0681081 A JPH0681081 A JP H0681081A JP 4232300 A JP4232300 A JP 4232300A JP 23230092 A JP23230092 A JP 23230092A JP H0681081 A JPH0681081 A JP H0681081A
- Authority
- JP
- Japan
- Prior art keywords
- steel sheet
- cold
- rolled steel
- temperature
- hot
- 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.)
- Withdrawn
Links
- 239000010960 cold rolled steel Substances 0.000 title claims abstract description 38
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 19
- 229910000831 Steel Inorganic materials 0.000 title abstract description 60
- 239000010959 steel Substances 0.000 title abstract description 60
- 238000000137 annealing Methods 0.000 claims abstract description 33
- 230000032683 aging Effects 0.000 claims abstract description 26
- 229910052748 manganese Inorganic materials 0.000 claims abstract description 25
- 230000009466 transformation Effects 0.000 claims description 25
- 229910052710 silicon Inorganic materials 0.000 claims description 15
- 229910052698 phosphorus Inorganic materials 0.000 claims description 14
- 238000005246 galvanizing Methods 0.000 claims description 13
- 238000005096 rolling process Methods 0.000 claims description 10
- 229910000859 α-Fe Inorganic materials 0.000 claims description 9
- 230000003679 aging effect Effects 0.000 claims description 4
- 229910052782 aluminium Inorganic materials 0.000 claims description 2
- 239000012535 impurity Substances 0.000 claims description 2
- 229910052804 chromium Inorganic materials 0.000 abstract description 22
- 229910001209 Low-carbon steel Inorganic materials 0.000 abstract description 19
- 238000005482 strain hardening Methods 0.000 abstract description 9
- 239000003973 paint Substances 0.000 abstract description 6
- 238000007747 plating Methods 0.000 description 17
- 239000002131 composite material Substances 0.000 description 12
- 239000000463 material Substances 0.000 description 10
- 230000001965 increasing effect Effects 0.000 description 9
- 238000005728 strengthening Methods 0.000 description 9
- 238000007792 addition Methods 0.000 description 8
- 238000005275 alloying Methods 0.000 description 7
- 238000006243 chemical reaction Methods 0.000 description 7
- 238000001816 cooling Methods 0.000 description 7
- 238000009864 tensile test Methods 0.000 description 7
- 230000006866 deterioration Effects 0.000 description 6
- 230000000694 effects Effects 0.000 description 6
- 238000005098 hot rolling Methods 0.000 description 6
- 238000000034 method Methods 0.000 description 6
- 229910052758 niobium Inorganic materials 0.000 description 6
- 239000006104 solid solution Substances 0.000 description 6
- 238000005097 cold rolling Methods 0.000 description 5
- 238000010438 heat treatment Methods 0.000 description 5
- 230000009467 reduction Effects 0.000 description 5
- 230000035882 stress Effects 0.000 description 5
- 230000007423 decrease Effects 0.000 description 4
- 238000002791 soaking Methods 0.000 description 4
- 239000011248 coating agent Substances 0.000 description 3
- 238000000576 coating method Methods 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 238000000227 grinding Methods 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 239000011701 zinc Substances 0.000 description 3
- 229910001335 Galvanized steel Inorganic materials 0.000 description 2
- RQMIWLMVTCKXAQ-UHFFFAOYSA-N [AlH3].[C] Chemical compound [AlH3].[C] RQMIWLMVTCKXAQ-UHFFFAOYSA-N 0.000 description 2
- 230000008859 change Effects 0.000 description 2
- 239000008397 galvanized steel Substances 0.000 description 2
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 2
- 229910052757 nitrogen Inorganic materials 0.000 description 2
- 238000005554 pickling Methods 0.000 description 2
- 238000003825 pressing Methods 0.000 description 2
- 238000009628 steelmaking Methods 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 230000007704 transition Effects 0.000 description 2
- 238000004804 winding Methods 0.000 description 2
- 229910000975 Carbon steel Inorganic materials 0.000 description 1
- 229910000885 Dual-phase steel Inorganic materials 0.000 description 1
- 229910000655 Killed steel Inorganic materials 0.000 description 1
- 238000002441 X-ray diffraction Methods 0.000 description 1
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 1
- 239000002390 adhesive tape Substances 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 238000005452 bending Methods 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 150000001875 compounds Chemical group 0.000 description 1
- 230000002950 deficient Effects 0.000 description 1
- 230000002708 enhancing effect Effects 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 230000001771 impaired effect Effects 0.000 description 1
- 238000011835 investigation Methods 0.000 description 1
- 229910000734 martensite Inorganic materials 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 230000002265 prevention Effects 0.000 description 1
- 230000003449 preventive effect Effects 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 239000004575 stone Substances 0.000 description 1
- 238000004381 surface treatment Methods 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 238000009849 vacuum degassing Methods 0.000 description 1
- 229910052725 zinc Inorganic materials 0.000 description 1
Landscapes
- Coating With Molten Metal (AREA)
- Heat Treatment Of Steel (AREA)
- Heat Treatment Of Sheet Steel (AREA)
Abstract
(57)【要約】
【目的】 本発明は、優れた焼付硬化性と常温非時効性
を兼ね備えた冷延鋼板と溶融亜鉛メッキ冷延鋼板ならび
にその製造方法を提供する。
【構成】 極低炭素鋼をベースにＭｎやＣｒを積極的に
添加することにより焼鈍後の組織を混合組織とする。こ
れにより降伏強度は低く、著しく加工硬化し、高い塗装
焼付硬化能をあわせ持ち、平均ｒ値（深絞り特性）や伸
び（張出特性）などの加工性にも優れる鋼板を得ること
ができる。特に塗装焼付硬化能に関しては、１０ｋｇｆ
／ｍｍ2 程度までの高いＢＨ量を必要に応じて付与する
ことができ、かつ常温非時効性を兼ね備えた冷延鋼板と
溶融亜鉛メッキ冷延鋼板を提供することが可能である。(57) [Summary] [Object] The present invention provides a cold-rolled steel sheet, a hot-dip galvanized cold-rolled steel sheet, and a method for producing the same, which have both excellent bake hardenability and non-aging at room temperature. [Structure] The structure after annealing is made into a mixed structure by actively adding Mn and Cr to the base of ultra-low carbon steel. As a result, it is possible to obtain a steel sheet that has a low yield strength, undergoes work hardening, has a high paint bake hardening ability, and has excellent workability such as average r value (deep drawing property) and elongation (protrusion property). Especially for paint bake hardenability, 10 kgf
It is possible to provide a high BH amount of up to about / mm 2 as needed, and to provide a cold-rolled steel sheet and a hot-dip galvanized cold-rolled steel sheet having both non-aging at room temperature.
Description
【０００１】[0001]
【産業上の利用分野】本発明は、優れた焼付硬化性と常
温非時効性を兼備した冷延鋼板と溶融亜鉛メッキ冷延鋼
板およびその製造方法に関する。本発明に係わる冷延鋼
板とは、自動車、家庭電気製品、建物などのプレス成形
をして使用されるものである。そして、表面処理をしな
い狭義の冷延鋼板と、防錆のために、例えばＺｎメッキ
や合金化Ｚｎメッキなどの表面処理を施した冷延鋼板の
両方を含む。本発明による鋼板は、強度と加工性を兼ね
備えた鋼板であるので、使用に当たっては今までの鋼板
より板厚を減少できること、すなわち軽量化が可能とな
る。したがって、地球環境保全に寄与できるものと考え
られる。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cold-rolled steel sheet and a hot-dip galvanized cold-rolled steel sheet having excellent bake hardenability and non-aging at room temperature, and a method for producing the same. The cold-rolled steel sheet according to the present invention is used by press forming automobiles, household electric appliances, buildings and the like. Further, it includes both a cold-rolled steel sheet in a narrow sense that is not surface-treated and a cold-rolled steel sheet that has been subjected to surface treatment such as Zn plating or alloyed Zn plating for rust prevention. Since the steel sheet according to the present invention is a steel sheet having both strength and workability, it is possible to reduce the plate thickness in use, that is, to reduce the weight, in use. Therefore, it is considered that it can contribute to global environment conservation.
【０００２】[0002]
【従来の技術】溶鋼の真空脱ガス処理の最近の進歩によ
り、極低炭素鋼の溶製が容易になった現在、良好な加工
性を有する極低炭素鋼板の需要は益々増加しつつある。
この中でも、例えば特開昭５９−３１８２７号公報およ
び特開昭５９−３８３３７号公報などに開示されている
ＴｉとＮｂを複合添加した極低炭素鋼板は、きわめて良
好な加工性を有し、塗装焼付硬化（ＢＨ）性を兼備し、
溶融亜鉛メッキ特性にも優れているので、重要な位置を
しめつつある。しかしながら、そのＢＨ量は通常のＢＨ
鋼板のレベルを超えるものではなく、さらなるＢＨ量を
付与しようとすると常温非時効性が確保できなくなると
いう欠点を有する。さらに、ＴｉやＮｂを含有しない、
加工性に優れた極低炭素鋼板についても数多く開示され
ている。特公昭５３−２２０５２号公報、特開昭５８−
１３６７２１号公報、特開昭５８−１４１３３５号公報
などがその例である。2. Description of the Related Art Recent advances in vacuum degassing of molten steel have facilitated the melting of ultra-low carbon steel, and nowadays, the demand for ultra-low carbon steel sheets having good workability is increasing.
Among them, for example, the ultra-low carbon steel sheet to which Ti and Nb are added in combination, which are disclosed in JP-A-59-31827 and JP-A-59-38337, have extremely good workability and are coated. Combined with bake hardening (BH),
Since it has excellent hot-dip galvanizing properties, it is becoming an important position. However, the amount of BH is normal BH
It does not exceed the level of the steel sheet, and has a drawback that the room-temperature non-aging cannot be secured if an attempt is made to add a further BH amount. Furthermore, it does not contain Ti or Nb,
Many very low carbon steel sheets having excellent workability are also disclosed. JP-B-53-22052, JP-A-58-
Examples are 136721 and JP-A-58-141335.
【０００３】一方、加工性を確保しつつ強度を上昇させ
るために、従来から多くの試みがなされてきた。特に、
本発明が関わる引張強度が３０〜５０ｋｇｆ／ｍｍ2 の
場合には、鋼中にＰ、Ｓｉなどを添加し、これらの固溶
体強化機構を利用して強度を増加してきた。例えば、特
開昭５９−３１８２７号公報および特開昭５９−３８３
３７号公報においては、ＴｉとＮｂを添加した極低炭素
鋼板に主にＳｉとＰを添加し、引張強度で４５ｋｇｆ／
ｍｍ2 級までの高強度冷延鋼板の製造方法を開示してい
る。特公昭５７−５７９４５号公報はＴｉ添加極低炭素
鋼にＰを添加して高強度冷延鋼板を製造する方法に関す
る代表的な先行技術である。さらに、Ｔｉ、Ｎｂを含有
しない極低炭素鋼においては、特公昭５８−５７４９２
号公報、特開昭５８−４８６３６号公報にはＰを添加し
て高強度化する技術、特開昭５７−４３９３２号公報に
はＳｉを活用する技術が開示されている。On the other hand, many attempts have heretofore been made to increase the strength while ensuring the workability. In particular,
When the tensile strength related to the present invention is 30 to 50 kgf / mm 2 , P, Si, etc. are added to steel and the strength is increased by utilizing the solid solution strengthening mechanism of these. For example, JP-A-59-31827 and JP-A-59-383.
According to Japanese Patent Laid-Open No. 37,37, Si and P are mainly added to an ultra-low carbon steel plate to which Ti and Nb are added, and the tensile strength is 45 kgf /
Disclosed is a method for manufacturing a high-strength cold-rolled steel sheet up to the mm 2 class. Japanese Patent Publication No. 57-57945 is a typical prior art relating to a method for producing a high-strength cold-rolled steel sheet by adding P to a Ti-added ultra-low carbon steel. Furthermore, in the case of ultra low carbon steel containing no Ti or Nb, Japanese Patent Publication No. 58-57492.
Japanese Patent Laid-Open No. 58-48636 and Japanese Patent Laid-Open No. 58-48636 disclose a technique for increasing the strength by adding P, and Japanese Laid-Open Patent Publication No. 57-43932 discloses a technique for utilizing Si.
【０００４】以上のように従来から強化元素としてＰ、
次いでＳｉが多用されている。これは、ＰやＳｉは固溶
体強化能が非常に高く少量の添加で強度を上昇でき、か
つ延性や深絞り性がそれほど低下せず、添加コストもそ
れほど上昇しないと考えられてきたからである。しか
し、実際にはこれらの元素だけで強度の上昇を達成しよ
うとすると強度のみならず降伏強度も同時に著しく上昇
するため、面形状不良が発生し、自動車のパネルには使
用が制約される場合がある。また、溶融亜鉛メッキをす
る場合にはメッキ不良をＳｉが惹起したり、Ｐ、Ｓｉが
合金化速度を著しく低下させたりするので、生産性が低
下したりする問題がある。As described above, P has been conventionally used as a strengthening element,
Next, Si is frequently used. This is because it has been considered that P and Si have a very high solid solution strengthening ability and can be added with a small amount to increase the strength, the ductility and the deep drawability do not decrease so much, and the addition cost does not increase so much. However, in actuality, if an attempt is made to increase the strength only with these elements, not only the strength but also the yield strength will increase significantly at the same time. is there. Further, in the case of hot dip galvanizing, Si causes a plating failure, and P and Si significantly reduce the alloying rate, so that there is a problem that productivity is lowered.
【０００５】一方、固溶体強化元素としてＭｎやＣｒを
利用することも知られている。特開昭６３−１９０１４
１号公報および特開昭６４−６２４４０号公報にはＭｎ
をＴｉ含有極低炭素鋼板へ添加する技術が、特公昭５９
−４２７４２号公報や前記した特公昭５７−５７９４５
号公報においては、ＭｎとＣｒをＴｉ添加極低炭素鋼へ
添加する技術が開示されている。また、特開昭６２−４
０３５２号公報にはＴｉやＮｂを含有しない極低炭素鋼
へＭｎを添加する技術が開示されているものの、（ｉ）
ＭｎやＣｒの添加は、主な添加元素であるＰやＳｉの補
助的な役割しかなく、したがって、得られた冷延鋼板も
強度のわりには降伏強度が高く、かつ（ii）上記（ｉ）
以外の目的で、例えば（ａ）本発明の特徴である焼鈍後
の組織を混合組織とするために添加されているのではな
いのはもちろんのこと、（ｂ）加工硬化率を向上させ
る、（ｃ）ＢＨ性を付与する、（ｄ）２次加工性を向上
させる、（ｅ）溶融亜鉛メッキのメッキ性を改善する、
などの目的で積極的に添加されているわけでもない。On the other hand, it is also known to utilize Mn or Cr as a solid solution strengthening element. JP-A-63-19014
No. 1 and JP-A-64-62440 disclose Mn.
The technology of adding Ti to the ultra-low carbon steel sheet containing Ti is
-42742 and Japanese Patent Publication No. 57-57945
In the publication, a technique of adding Mn and Cr to a Ti-added ultra-low carbon steel is disclosed. In addition, JP-A-62-4
Japanese Patent No. 0352 discloses a technique of adding Mn to an ultra-low carbon steel containing no Ti or Nb, but (i)
The addition of Mn and Cr has only a supplementary role of P and Si which are the main additional elements, and therefore the obtained cold-rolled steel sheet also has a high yield strength for strength, and (ii) above (i)
For other purposes, for example, (a) it is not added in order to make the structure after annealing, which is a feature of the present invention, into a mixed structure, and (b) improves the work hardening rate, c) imparting BH property, (d) improving secondary workability, (e) improving plating property of hot dip galvanizing,
It is not positively added for the purpose such as.
【０００６】さらに、特開平２−１１１８４１号公報
は、Ｔｉを添加した極低炭素鋼に１．５％以上３．５％
未満のＭｎを添加した焼付硬化性を有する良加工性冷延
鋼板および溶融亜鉛メッキ鋼板を開示している。多量の
Ｍｎの添加により、Ａｒ3 変態点の低下による熱間圧延
の操業安定性と金属組織の均一性を目的としている。ま
た、一層の延性の向上を目的にＣｒやＶの０．２〜１．
０％までの添加も開示している。しかし、多量のＭｎや
Ｃｒの添加により機械的性質、特に強度と延性のバラン
スを改善するという思想に基づくものではない。さら
に、ここでもＢＨ量は通常のレベルから逸脱するもので
はなく、これまで以上の高いＢＨと常温非時効性を両立
するには至っていない。Further, Japanese Patent Laid-Open No. 2-111841 discloses that ultra-low carbon steel containing Ti has 1.5% or more and 3.5% or more.
Disclosed are a good workability cold-rolled steel sheet and a hot-dip galvanized steel sheet having bake hardenability containing less than Mn. By adding a large amount of Mn, the purpose is to improve the operation stability of hot rolling and the homogeneity of the metal structure due to the reduction of the Ar 3 transformation point. Further, for the purpose of further improving the ductility, 0.2 to 1.
Additions up to 0% are also disclosed. However, it is not based on the idea of improving the mechanical properties, particularly the balance between strength and ductility, by adding a large amount of Mn or Cr. Furthermore, the amount of BH does not deviate from the normal level even here, and it has not reached the point where both higher BH than ever before and non-aging at room temperature are compatible.
【０００７】以上のような、フェライト単相組織を有す
る鋼板に対して、複合組織を有する鋼板も知られてい
る。低炭素アルミキルド鋼にＳｉ、Ｍｎ、Ｃｒなどの合
金元素を添加し、連続焼鈍温度とその後の冷却速度を適
正化することにより、フェライト相とマルテンサイト相
とを混在させた、いわゆるＤｕａｌ Ｐｈａｓｅ鋼（Ｄ
Ｐ鋼）と呼ばれるものがその代表例である。このような
ＤＰ鋼は、高強度でありながらきわめて低い降伏比（Ｙ
Ｒ）を有し、かつ常温非時効で高いＢＨを有することが
知られている。しかしながら、平均ｒ値が１．０程度と
低く、深絞り性に劣るという欠点を有する。ちなみにこ
のような冷延鋼板の製造方法については、特公昭５３−
３９３６８号、特開昭５０−７５１１３号、特開昭５１
−３９５２４号の各公報に開示されている。In contrast to the steel sheet having a ferrite single phase structure as described above, a steel sheet having a composite structure is also known. By adding alloying elements such as Si, Mn, and Cr to low carbon aluminum killed steel and optimizing the continuous annealing temperature and the subsequent cooling rate, so-called Dual Phase steel (mixed with ferrite phase and martensite phase ( D
What is called P steel) is a typical example. Such DP steel has a high yield strength but a very low yield ratio (Y
It is known to have R) and have a high BH at room temperature and non-aging. However, it has a drawback that the average r value is as low as about 1.0 and the deep drawability is poor. By the way, the manufacturing method of such a cold rolled steel sheet is described in Japanese Patent Publication No. 53-
39368, JP-A-50-75113, JP-A-51
-39524.
【０００８】これらの低炭素アルミキルド鋼を素材とし
た複合組織鋼板に対して、特公平３−２２２４号公報、
特公平３−２１６１１号公報および特開平３−２７７７
４１号公報には極低炭素鋼を素材とした複合組織鋼板に
ついて開示されている。これらは極低炭素鋼に多量のＮ
ｂとＢ、さらにはＴｉを複合添加して焼鈍後の組織をフ
ェライト相と低温変態生成相との複合組織とし、高ｒ
値、高ＢＨ、高延性および常温非時効性を兼ね備えた冷
延鋼板を得るものである。さらに、特開昭６０−１９７
８４６号公報には、ＴｉやＮｂを含有しない極低炭素鋼
に多量のＢを添加することによって上記のような特性を
得る技術が開示されている。しかしながら、本発明者ら
が鋭意検討した結果、このように多量のＢを添加するこ
とによって複合組織化する場合には、以下のような問題
点を有することが明らかとなった。Japanese Patent Publication No. 3-2224 discloses a steel sheet having a composite structure composed of these low carbon aluminum killed steels.
JP-B-3-21611 and JP-A-3-2777.
Japanese Unexamined Patent Publication No. 41 discloses a steel sheet having a composite structure made of ultra-low carbon steel. These are very low carbon steels with large amounts of N
b and B, and further Ti are added together to make the structure after annealing into a composite structure of a ferrite phase and a low temperature transformation forming phase.
It is intended to obtain a cold-rolled steel sheet having both high value, high BH, high ductility and non-aging at room temperature. Furthermore, JP-A-60-197
Japanese Patent Publication No. 846 discloses a technique for obtaining the above-mentioned characteristics by adding a large amount of B to an ultra-low carbon steel containing no Ti or Nb. However, as a result of diligent studies by the present inventors, it was revealed that the following problems occur when the compound structure is formed by adding such a large amount of B.
【０００９】１）このような多量のＢを含有する成分の
鋼では、Ａｃ1 変態点が低下するわけではなく、複合組
織を得るためにはきわめて高い温度の焼鈍が必須とな
り、連続焼鈍時に板破断等のトラブルの原因となる。 ２）α＋γの温度領域がきわめて狭いため、板幅方向に
組織が変化し、結果として材質が大きくばらついたり、
数℃の焼鈍温度の変化によって複合組織になる場合とな
らない場合があり、製造がきわめて不安定となる。1) In the steel containing such a large amount of B, the Ac 1 transformation point does not decrease, and annealing at an extremely high temperature is essential to obtain a composite structure. It causes troubles such as breakage. 2) Since the temperature range of α + γ is extremely narrow, the structure changes in the plate width direction, resulting in large variations in the material,
A change in annealing temperature of several degrees Celsius may or may not result in a composite structure, resulting in extremely unstable production.
【００１０】さらに多量のＢは、 ３）延性の劣化をもたらす。 ４）めっき不良等の原因となり、溶融亜鉛メッキ鋼板と
しては不適切である。 ５）また、５ｋｇｆ／ｍｍ2 以上のＢＨを付与すること
が困難でなるばかりか、ＢＨ量が５ｋｇｆ／ｍｍ2 を超
えると人工時効後のＹＰ−Ｅｌが０．２％を超えてしま
い、常温非時効性が確保されなくなる。A larger amount of B causes 3) deterioration of ductility. 4) It causes plating failure and is not suitable as a galvanized steel sheet. 5) Further, it is difficult to apply BH of 5 kgf / mm 2 or more, and when the BH amount exceeds 5 kgf / mm 2 , YP-El after artificial aging exceeds 0.2%, and the room temperature is Non-prescription is not secured.
【００１１】さらに、特開昭５８−４８６３６号公報な
らびに特開昭５７−２０３７２１号公報には、Ｔｉ、Ｎ
ｂを添加していない極低炭素鋼に多量のＢを添加して７
３０℃〜Ａ3 点で焼鈍することにより焼付硬化性と深絞
り性に優れた冷延鋼板の製造方法が開示されている。し
かしながら、これらはフェライト単相組織であることが
前提となっているので、本発明とは全く異なるものであ
る。Further, in JP-A-58-48636 and JP-A-57-203721, Ti and N are disclosed.
7) by adding a large amount of B to ultra low carbon steel not containing b
Disclosed is a method for producing a cold-rolled steel sheet having excellent bake hardenability and deep drawability by annealing at 30 ° C to A 3 points. However, these are completely different from the present invention because they are assumed to have a ferrite single-phase structure.
【００１２】以上のように極低炭素鋼における複合組織
鋼板についていくつかの提案がなされているが、そのＢ
Ｈ量は到底従来レベルを逸脱するものではなく、常温非
時効性についても従来のレベルをわずかに上回る程度に
とどまっていた。As described above, several proposals have been made for a steel sheet having a composite structure in ultra low carbon steel.
The H content did not deviate from the conventional level at all, and the room temperature non-aging property was slightly higher than the conventional level.
【００１３】[0013]
【発明が解決しようとする課題】自動車のパネルなどに
使用される鋼板には、プレスの後にスプリングバックや
面歪などが生じない良好な面形状性が厳しく要求され
る。ところで、面形状性は、降伏強度が低いほど好まし
いことはよく知られている。しかし、鋼板の高強度化
は、従来技術で述べたように一般に降伏強度の著しい上
昇を伴う。したがって、強度を上昇させる場合には、降
伏強度の上昇を極力抑制する必要がある。Steel sheets used for automobile panels and the like are strictly required to have good surface formability without causing springback or surface distortion after pressing. By the way, it is well known that the lower the yield strength is, the more preferable the surface shape property is. However, increasing the strength of a steel sheet generally involves a marked increase in the yield strength as described in the prior art. Therefore, when increasing the strength, it is necessary to suppress the increase in yield strength as much as possible.
【００１４】さらに、プレス成形をしたあとの鋼板には
耐デント性が要求される。耐デント性とは、組上がった
自動車に石などが当たる場合、鋼板の永久的な凹み変形
に対する抵抗性を意味する。耐デント特性は、板厚が一
定の場合、プレス加工して塗装焼付したのちの変形応力
が高いほど良好になる。したがって同じ降伏強度の鋼板
を考えた場合、塗装焼付硬化能が高く、また加工硬化能
が高いほど耐デント特性は向上することになる。Further, the steel sheet after press forming is required to have dent resistance. The dent resistance means resistance to permanent dent deformation of a steel sheet when a stone or the like hits the assembled automobile. When the plate thickness is constant, the dent resistance property becomes better as the deformation stress after press working and paint baking becomes higher. Therefore, when a steel sheet having the same yield strength is considered, the higher the coating bake hardening ability and the higher the work hardening ability, the higher the dent resistance property.
【００１５】以上から、自動車のパネルなどに使用され
る望ましい鋼板は、降伏強度はそれほど高くなく、著し
く加工硬化し、高い塗装焼付硬化能をあわせ持つ鋼板で
ある。もちろん、平均ｒ値（深絞り特性）や伸び（張出
特性）などの加工性にも優れる必要があり、さらに常温
で実質的に非時効である必要がある。本発明は、以上の
ような要望を満足するものであって、特に塗装焼付硬化
能に関しては、１０ｋｇｆ／ｍｍ2 程度までの高いＢＨ
量を目的に応じて付与することができ、かつ常温非時効
性を兼ね備えた、従来にはない冷延鋼板および溶融亜鉛
メッキ冷延鋼板を提供することを目的とするものであ
る。From the above, a desirable steel sheet used for an automobile panel or the like is a steel sheet having a not so high yield strength, undergoing remarkable work hardening and having a high paint bake hardening ability. Of course, it is also necessary to be excellent in workability such as average r value (deep drawing property) and elongation (prolongation property), and it is also necessary to be substantially non-aging at room temperature. The present invention satisfies the above-mentioned demands, and particularly with respect to coating bake hardening ability, a high BH of up to about 10 kgf / mm 2.
It is an object of the present invention to provide a cold-rolled steel sheet and a hot-dip galvanized cold-rolled steel sheet which have not been hitherto available and which can be added in an amount according to the purpose and have a non-aging property at room temperature.
【００１６】[0016]
【課題を解決するための手段】本発明者らは、上記の目
的を達成するために、鋭意、研究を遂行し、以下に述べ
るような従来にはない知見を得た。すなわち、ＮｂやＴ
ｉを含有しない極低炭素鋼をベースにして、Ｂ、Ｍｎ、
Ｃｒの冷間圧延、焼鈍、調質圧延後の組織と引張特性、
特に焼鈍時のα→γ変態挙動に着目して詳細に調査し
た。その結果、Ｂを添加することによってフェライトと
低温変態生成物からなる複合組織を得ることができた
が、１）複合組織とするためには通常よりもかなり高い
温度での焼鈍が必須であること、２）しかも複合組織と
するための温度域は、きわめて狭い範囲しか存在しない
ため、製造時に材質のばらつきがきわめて大きいこと、
３）さらに、このような鋼ではＢＨを５ｋｇｆ／ｍｍ2
以上付与することは困難であるばかりか、ＢＨが５ｋｇ
ｆ／ｍｍ2以上となると人工時効後の降伏点伸び（ＹＰ
−Ｅｌ）が０．２％を超えてしまい、常温非時効性が確
保されなくなること、また４）焼鈍後の冷却条件にきわ
めて鈍感で、このこともＢＨ量、ｒ値等の材質特性を著
しく不安定にすることを確かめた。[Means for Solving the Problems] The inventors of the present invention have earnestly conducted research in order to achieve the above-mentioned object, and obtained the following unprecedented findings. That is, Nb and T
Based on ultra low carbon steel containing no i, B, Mn,
Structure and tensile properties after cold rolling, annealing and temper rolling of Cr,
In particular, a detailed investigation was conducted focusing on the α → γ transformation behavior during annealing. As a result, it was possible to obtain a composite structure composed of ferrite and a low temperature transformation product by adding B. 1) In order to form a composite structure, annealing at a temperature considerably higher than usual is essential. 2) Moreover, since the temperature range for forming the composite structure is extremely narrow, there is a great variation in the materials during manufacturing.
3) Furthermore, in such steel, BH is 5 kgf / mm 2
Not only is it difficult to give above, but BH is 5 kg
When f / mm 2 or more, the yield point elongation (YP
-El) exceeds 0.2%, so that non-aging at room temperature cannot be ensured, and 4) is extremely insensitive to the cooling conditions after annealing. This also shows that the material properties such as BH amount and r value are remarkably high. I've confirmed that it will be unstable.
【００１７】これに対して、Ｍｎまたは／およびＣｒを
添加した鋼においては、１）これらの元素がγ形成元素
であるため極低炭素鋼でありながらＡｃ1 変態点が低
く、それほど高い焼鈍温度を必要とせず、かつ２）きわ
めて広いα＋γ２相領域を有するため製造時の材質ばら
つきがきわめて小さく、さらに３）容易に５ｋｇｆ／ｍ
ｍ2 以上のＢＨ量を付与することができ、またたとえＢ
Ｈ量が１０ｋｇｆ／ｍｍ 2 程度となっても、人工時効後
のＹＰ−Ｅｌが０．２％を超えることはなく、非常に優
れた常温非時効性とＢＨ性とを両立することが分かっ
た。この原因は必ずしも明らかではないが、ＭｎやＣｒ
を用いて混合組織とした鋼においては、生成する低温変
態生成物中およびこのまわりに導入されるフェライト中
の可動転位密度がＢの複合添加によって得た複合組織の
それよりもかなり高いことが原因であると思われる。ま
た、４）Ｍｎ、Ｃｒを添加した混合組織鋼板においては
ｒ値、ＢＨ等の機械的性質が焼鈍後の冷却条件によらず
良好であり、製造が容易であることも大きな特徴の１つ
である。また、理由は必ずしも明らかではないものの、
これらの性質はたとえＭｎやＣｒを添加した鋼であって
も、同時にＢが多量に添加されすぎると達成されないも
のである。On the other hand, Mn or / and Cr
In the added steel, 1) these elements are gamma forming elements.
Therefore, even though it is an ultra-low carbon steel, Ac1Low transformation point
And does not require very high annealing temperature, and 2)
Since it has a wide α + γ2 phase region,
Extremely small stickiness, and 3) easily 5 kgf / m
m2The above BH amount can be given, and even if B
H amount is 10 kgf / mm 2After artificial aging
YP-El of 0.2% does not exceed 0.2%.
It was found that both room temperature non-aging property and BH property are compatible.
It was The cause of this is not always clear, but Mn and Cr
In the case of steel with a mixed structure using
In the state product and in the ferrite introduced around this
With a mobile dislocation density of B
It seems that the reason is much higher than that. Well
4) In the mixed structure steel sheet to which Mn and Cr are added,
Mechanical properties such as r-value and BH do not depend on cooling conditions after annealing
One of the major characteristics is that it is good and easy to manufacture.
Is. Also, although the reason is not always clear,
These properties, even if Mn and Cr added steel
However, if B is added too much at the same time, it cannot be achieved.
Of.
【００１８】次に高強度化する際の強化元素として考え
られるＭｎ、Ｃｒ、Ｐ、Ｓｉがそれぞれ機械的性質に対
していかなる影響を及ぼすかについて検討した結果、以
下のような新知見を得た。すなわち、従来から固溶強化
元素として多用されているＳｉ、Ｐは、ａ）まず微量の
添加で著しく降伏強度を上昇させること、ｂ）その結
果、低歪域での加工硬化率が著しく減少することが判明
した。Next, as a result of studying how each of Mn, Cr, P and Si, which are considered to be strengthening elements for strengthening, affect mechanical properties, the following new findings were obtained. . That is, Si and P, which have been widely used as solid solution strengthening elements in the past, a) first increase the yield strength remarkably by adding a small amount, and b) as a result, the work hardening rate in the low strain range is remarkably reduced. It has been found.
【００１９】一方、従来固溶体強化元素としてあまり用
いられていないＭｎ、Ｃｒを添加すると、ａ）降伏強度
は殆ど増加せず、引張強度が増加し、ｂ）その結果、低
歪域での加工硬化率がむしろこれらの添加により増加す
る、というきわめて重要な新知見を得た。Ｍｎ、Ｃｒで
混合組織としたことに加えて、このことも本発明鋼が低
降伏比を呈する理由であると思われる。また、このよう
な、Ｐ、Ｓｉの低減は、Ａc1点を低下させる点において
も意義のあることである。On the other hand, when Mn and Cr, which have not been used so far as solid solution strengthening elements, are added, a) yield strength is hardly increased and tensile strength is increased. B) As a result, work hardening in a low strain region We gained a very important new finding that the rate increases with these additions. In addition to having a mixed structure of Mn and Cr, this also seems to be the reason why the steel of the present invention exhibits a low yield ratio. Further, such reduction of P and Si is also significant in reducing the Ac 1 point.
【００２０】さらに、本発明者らは、本発明鋼が溶融亜
鉛メッキ冷延鋼板としても長所を有することが分かっ
た。すなわち、ＳｉやＰが多量に添加された鋼において
は溶融亜鉛メッキ時のメッキ性、さらにはその後の合金
化反応の遅滞化を引き起こすことが知られているが、Ｍ
ｎやＣｒを添加した鋼においては、たとえ同時にＳｉや
Ｐが多量に含有されている場合でも溶融亜鉛メッキ特性
を損なうことがないことが判明した。さらにＢの影響に
ついても検討し、多量のＢは溶融亜鉛メッキにおけるメ
ッキ性、および合金化反応特性に悪影響を及ぼすことが
明らかとなった。Further, the present inventors have found that the steel of the present invention has an advantage as a hot-dip galvanized cold-rolled steel sheet. That is, it is known that in a steel to which a large amount of Si or P is added, the plating property at the time of hot dip galvanization and the delay of the subsequent alloying reaction are caused.
It has been found that the steel added with n or Cr does not impair the hot-dip galvanizing property even if it contains a large amount of Si or P at the same time. Furthermore, the influence of B was also examined, and it was revealed that a large amount of B adversely affects the plating property in hot dip galvanizing and the alloying reaction characteristics.
【００２１】本発明は、このような思想と新知見に基づ
いて構築されたものであり、その要旨とするところは以
下のとおりである。 （１） 重量％で、Ｃ：０．０００５〜０．００７０
％、Ｓｉ：０．００１〜０．８％、Ｍｎ：０．３〜４．
０％、Ｐ：０．００３〜０．１５％、Ｓ：０．０００５
〜０．０１５％、Ａｌ：０．００５〜０．２０％、Ｎ：
０．０００３〜０．００６０％、残部Ｆｅおよび不可避
的不純物からなる組成にして、低温変態生成物とフェラ
イトとからなる混合組織を有することを特徴とする優れ
た焼付硬化性と常温非時効性を兼備した冷延鋼板と溶融
亜鉛メッキ冷延鋼板。The present invention is constructed on the basis of such an idea and new knowledge, and the gist thereof is as follows. (1) C: 0.0005 to 0.0070 in% by weight
%, Si: 0.001-0.8%, Mn: 0.3-4.
0%, P: 0.003 to 0.15%, S: 0.0005
~ 0.015%, Al: 0.005 to 0.20%, N:
Excellent bake hardenability and non-aging at room temperature characterized by having a composition of 0.0003 to 0.0060% with the balance being Fe and unavoidable impurities and having a mixed structure of a low temperature transformation product and ferrite. Combined cold-rolled steel sheet and hot-dip galvanized cold-rolled steel sheet.
【００２２】（２） Ｂ：０．００３０％未満かつＢ／
Ｎ≦１．５を満たすＢを含有する前項１記載の優れた焼
付硬化性と常温非時効性を兼備した冷延鋼板と溶融亜鉛
メッキ冷延鋼板。 （３） Ｃｒ：０．０１〜３．０％を含有する前項１ま
たは２記載の優れた焼付硬化性と常温非時効性を兼備し
た冷延鋼板と溶融亜鉛メッキ冷延鋼板。 （４） スラブを（Ａｒ3 −１００）℃以上の温度で熱
間圧延の仕上げを行い、室温から７５０℃の温度で巻取
り、６０％以上の圧延率で冷間圧延を行い、連続焼鈍に
おける焼鈍温度をＡc1変態点以上かつＡc3変態点以下と
することを特徴とする前項１〜３のいずれかに記載の優
れた焼付硬化性と常温非時効性を兼備した冷延鋼板の製
造方法。(2) B: less than 0.0030% and B /
A cold-rolled steel sheet and a hot-dip galvanized cold-rolled steel sheet having B excellent in bake hardenability and non-aging at room temperature as described in 1 above, which contains B satisfying N ≦ 1.5. (3) A cold-rolled steel sheet and a hot-dip galvanized cold-rolled steel sheet containing Cr: 0.01 to 3.0%, which have both the excellent bake hardenability and non-aging at room temperature as described in 1 or 2 above. (4) The slab is finished by hot rolling at a temperature of (Ar 3 -100) ° C. or higher, wound at a temperature of 750 ° C. from room temperature, cold rolled at a rolling rate of 60% or more, and then subjected to continuous annealing. A method for producing a cold-rolled steel sheet having both excellent bake hardenability and room temperature non-aging resistance as set forth in any one of the preceding items 1 to 3, characterized in that an annealing temperature is set to an Ac 1 transformation point or more and an Ac 3 transformation point or less. .
【００２３】（５） スラブを（Ａｒ3 −１００）℃以
上の温度で熱間圧延の仕上げを行い、室温から７５０℃
の温度で巻取り、６０％以上の圧延率で冷間圧延を行
い、焼鈍温度をＡc1変態点以上かつＡc3変態点以下とし
たインライン焼鈍型の溶融亜鉛メッキを施すことを特徴
とする前項１〜３のいずれかに記載の優れた焼付硬化性
と常温非時効性を兼備した溶融亜鉛メッキ冷延鋼板の製
造方法。(5) The slab is hot-rolled and finished at a temperature of (Ar 3 -100) ° C. or higher, and the temperature is increased from room temperature to 750 ° C.
The in-line annealing type hot dip galvanizing is carried out at a temperature of 10 %, cold rolling at a rolling rate of 60% or more, and an annealing temperature of Ac 1 transformation point or more and Ac 3 transformation point or less. A method for producing a hot-dip galvanized cold-rolled steel sheet having both excellent bake hardenability and non-aging at room temperature according to any one of 1 to 3.
【００２４】[0024]
【作用】ここに本発明において鋼組成および製造条件を
上述のように限定する理由についてさらに説明する。 Ｃ：Ｃは製品の材質特性を決定するきわめて重要な元素
である。本発明は真空脱ガス処理をした極低炭素鋼を前
提とするが、Ｃが０．０００５％未満となると粒界強度
が低下し、２次加工性が劣化し、かつ製造コストが著し
く増加するので、その下限を０．０００５％とする。一
方、Ｃ量が０．００７０％を超えると成形性の劣化を招
き、また常温非時効性が確保されなくなるので、上限を
０．００７０％とする。The reason why the steel composition and manufacturing conditions are limited as described above in the present invention will be further described. C: C is an extremely important element that determines the material properties of the product. The present invention is premised on a vacuum degassed ultra low carbon steel, but if C is less than 0.0005%, the grain boundary strength decreases, the secondary workability deteriorates, and the manufacturing cost significantly increases. Therefore, the lower limit is made 0.0005%. On the other hand, when the amount of C exceeds 0.0070%, the formability is deteriorated and the room-temperature non-aging cannot be ensured, so the upper limit is made 0.0070%.
【００２５】Ｓｉ：Ｓｉは安価に強度を増加させる元素
として知られており、その添加量は狙いとする強度レベ
ルに応じて変化するが、添加量が０．８％超となると降
伏強度が上昇しすぎてプレス成形時に面歪が生じる。ま
た、Ａc1変態点が上昇し、混合組織を得るための焼鈍温
度が著しく高くなる。さらに、化成処理性の低下、溶融
亜鉛メッキ密着性の低下、合金化反応の遅延による生産
性の低下などの問題が生ずる。下限は、製鋼技術および
コストの観点から０．００１％とする。Si: Si is known as an element that inexpensively increases the strength, and its addition amount changes depending on the target strength level, but if the addition amount exceeds 0.8%, the yield strength increases. If too much, surface distortion occurs during press molding. Further, the Ac 1 transformation point rises, and the annealing temperature for obtaining the mixed structure becomes extremely high. Further, problems such as deterioration of chemical conversion treatment property, deterioration of adhesion of hot dip galvanizing, and deterioration of productivity due to delay of alloying reaction occur. The lower limit is 0.001% from the viewpoint of steelmaking technology and cost.
【００２６】Ｍｎ、Ｃｒ：ＭｎおよびＣｒは、本発明に
おいて最も重要な元素のである。すなわちＭｎ、Ｃｒ
は、Ａc1変態点を低下させるため混合組織を得るために
それほど高い温度を必要とせず、かつα＋γ２相領域を
拡大するため、混合組織の体積分率をコントロールしや
すく、製造時の材質のばらつきが少なく生産性の向上を
もたらす。しかも、Ｍｎ、Ｃｒを活用することによって
得た混合組織鋼板においては、通常では得られない５ｋ
ｇｆ／ｍｍ2 以上のＢＨ量を容易に付与することがで
き、５ｋｇｆ／ｍｍ2 以上のＢＨ量を有する場合にも非
常に優れた常温非時効性を示す。この性質は、ＭｎやＣ
ｒを活用して得た混合組織鋼板に特有のもので、フェラ
イト単相組織鋼板や多量のＢの添加によって得た複合組
織鋼板では得られない特性である。さらに重要な点は、
通常の鋼においては、α＋γ２相域で焼鈍すると著しく
ｒ値が劣化することが知られているが、Ｍｎ、Ｃｒを積
極的に添加した鋼においては、α＋γ領域で焼鈍して
も、ｒがほとんど劣化しないことである。また、Ｍｎ、
Ｃｒは降伏強度をあまり増加させずに強度を増加させる
有効な固溶体強化元素であり、かつ化成処理性を改善し
たり、溶融亜鉛メッキ性を改善する効果も有する。本発
明においてはＭｎを必須とし、Ｃｒは必要に応じて添加
する。すなわち、Ａc1変態点を低下させる、さらにはα
＋γ２相領域を拡大させるという観点からは、Ｃｒより
もＭｎの方が効果が高いので、Ｍｎを活用する。Ｃｒは
ＢＨ性を向上させる、加工硬化能を高める等の観点で優
れた効果を発揮するので、これらの特性をさらに高めた
い場合には添加する。Ｍｎについては０．３％未満の添
加では、上に述べた効果が顕著に現れないので、その下
限を０．３％とする。一方、４．０％を超えると良好な
混合組織が得られなくなるので上限を４．０％とする。
また、Ｃｒは０．０１％未満ではその効果が発揮されな
いので、下限を０．０１％とし、３．０％を超えるとや
はり良好な混合組織が得られなくなるので上限を３．０
％とする。Mn, Cr: Mn and Cr are the most important elements in the present invention. That is, Mn, Cr
Does not require a very high temperature to obtain a mixed structure because it lowers the Ac 1 transformation point, and expands the α + γ2 phase region, so it is easy to control the volume fraction of the mixed structure and the variation of the material during manufacturing Results in less productivity. Moreover, in a steel sheet having a mixed structure obtained by utilizing Mn and Cr, it cannot be obtained normally by 5k.
A BH amount of gf / mm 2 or more can be easily applied, and even when a BH amount of 5 kgf / mm 2 or more is exhibited, very good non-aging at room temperature is exhibited. This property is due to Mn and C
This is a characteristic peculiar to a mixed structure steel sheet obtained by utilizing r, and is a characteristic that cannot be obtained with a ferrite single phase steel sheet or a composite structure steel sheet obtained by adding a large amount of B. More importantly,
It is known that in ordinary steels, the r value deteriorates remarkably when annealed in the α + γ2 phase region. However, in steels in which Mn and Cr are positively added, even if annealed in the α + γ region, r It does not deteriorate. In addition, Mn,
Cr is an effective solid solution strengthening element that increases the strength without increasing the yield strength, and also has the effect of improving the chemical conversion treatment property and the hot dip galvanizing property. In the present invention, Mn is essential and Cr is added as needed. That is, the Ac 1 transformation point is lowered, and further α
From the viewpoint of expanding the + γ2 phase region, Mn is more effective than Cr, so Mn is used. Cr exhibits excellent effects from the viewpoint of improving the BH property, enhancing the work hardening ability, and the like, so it is added when these properties are desired to be further enhanced. With respect to Mn, if the addition amount is less than 0.3%, the above-mentioned effects do not remarkably appear, so the lower limit is made 0.3%. On the other hand, if it exceeds 4.0%, a good mixed structure cannot be obtained, so the upper limit is made 4.0%.
Further, if Cr is less than 0.01%, its effect is not exhibited, so the lower limit is made 0.01%, and if it exceeds 3.0%, a good mixed structure cannot be obtained, so the upper limit is 3.0.
%.
【００２７】Ｐ：ＰはＳｉと同様に安価に強度を上昇す
る元素として知られており、その添加量は狙いとする強
度レベルに応じて変化する。添加量が０．１５％超える
と混合組織を得るための焼鈍温度が著しく高くなり、ま
た降伏強度が増加し過ぎてプレス時に面形状不良を引き
起こす。さらに、連続溶融亜鉛メッキ時に合金化反応が
きわめて遅くなり、生産性が低下する。また、２次加工
性も劣化する。したがって、その上限値を０．１５％と
する。また、製鋼技術およびコストの観点から下限は
０．００３％とする。P: P is known as an element that increases the strength at a low cost like Si, and the amount of addition thereof changes depending on the target strength level. If the amount added exceeds 0.15%, the annealing temperature for obtaining the mixed structure becomes extremely high, and the yield strength increases too much, causing a defective surface shape during pressing. Further, the alloying reaction becomes extremely slow during continuous hot dip galvanizing, which lowers productivity. In addition, the secondary workability also deteriorates. Therefore, the upper limit value is set to 0.15%. The lower limit is 0.003% from the viewpoint of steelmaking technology and cost.
【００２８】Ｓ：Ｓ量は低い方が好ましいが、０．００
０５％未満になると製造コストが高くなるのでこれを下
限値とする。一方、０．０１５％超となるとＭｎＳが数
多く析出し、加工性が劣化するのでこれを上限値とす
る。 Ａｌ：Ａｌは脱酸調製およびＮの固定に使用するが、
０．００５％未満ではその効果が充分でない。一方、
０．２０％超になるとコストアップを招くので上限を
０．２０％とする。S: The lower the S content, the better, but 0.00
If it is less than 05%, the manufacturing cost increases, so this is made the lower limit. On the other hand, if it exceeds 0.015%, a large amount of MnS is precipitated and the workability deteriorates, so this is made the upper limit. Al: Al is used for deoxidation preparation and N fixing,
If it is less than 0.005%, the effect is not sufficient. on the other hand,
If it exceeds 0.20%, the cost increases, so the upper limit is made 0.20%.
【００２９】Ｎ：Ｎは低い方が好ましい。しかし、０．
０００３％未満にするには著しいコストアップを招く。
一方、あまり多いと多量のＡｌが必要になったり、加工
性が劣化したりするので０．００６０％を上限値とす
る。 Ｂ：Ｂは２次加工脆化の防止に有効であるので添加して
もよい。しかし、０．００３０％以上となるとＢＨ量が
５ｋｇｆ／ｍｍ2 を超える場合には常温非時効性が確保
できなくなる。また加工性の劣化の原因となるので上限
を０．００３０％未満とする。さらに、Ｂ／Ｎ＞１．５
となるとＢＮが多くなり加工性が劣化するので、Ｂ／Ｎ
≦１．５を満たす範囲でＢを添加する。N: N is preferably low. However, 0.
If it is less than 0003%, a significant cost increase is incurred.
On the other hand, if the amount is too large, a large amount of Al is required and the workability deteriorates, so 0.0060% is made the upper limit. B: B is effective in preventing secondary working embrittlement, and thus may be added. However, if it is 0.0030% or more, if the amount of BH exceeds 5 kgf / mm 2 , non-aging at room temperature cannot be secured. Further, it causes deterioration of workability, so the upper limit is made less than 0.0030%. Furthermore, B / N> 1.5
If so, the BN increases and the workability deteriorates.
B is added within a range satisfying ≦ 1.5.
【００３０】次に、製造条件の限定理由について述べ
る。熱延の仕上温度は製品板の加工性を確保するという
観点から（Ａｒ3 −１００）℃以上とする必要がある。
また、巻取温度は室温から７５０℃とする。本発明はそ
の製品材質が熱延巻取温度の影響をあまり受けないとい
う特徴を有する。これは、ＭｎやＣｒなどをかなり添加
しており、熱延板の組織が著しく微細で均一化している
ことが一因と考えられる。巻取温度の上限が７５０℃で
あることは、イル両端部での材質劣化に起因する歩留低
下を防止する観点から決定される。冷間圧延は通常の条
件でよく、焼鈍後の深絞り性を確保する目的からその圧
延率は６０％以上とする。Next, the reasons for limiting the manufacturing conditions will be described. The finishing temperature of hot rolling needs to be (Ar 3 -100) ° C. or higher from the viewpoint of ensuring workability of the product sheet.
The winding temperature is from room temperature to 750 ° C. The present invention is characterized in that the product material is not so much affected by the hot rolling coiling temperature. It is considered that this is because Mn, Cr, etc. are considerably added, and the structure of the hot-rolled sheet is extremely fine and uniform. The upper limit of the coiling temperature of 750 ° C. is determined from the viewpoint of preventing a decrease in yield due to material deterioration at both ends of the ill. Cold rolling may be performed under normal conditions, and the rolling rate is set to 60% or more for the purpose of ensuring deep drawability after annealing.
【００３１】連続焼鈍あるいはライン内焼鈍方式の連続
溶融亜鉛メッキ設備の焼鈍温度は、Ａｃ1 変態点以上か
つＡc3変態点以下とする。焼鈍温度がＡc1変態点未満で
は、本発明の特徴である第２相、すなわち低温変態生成
物を得ることはできない。また、Ａc3変態点を超える温
度で焼鈍すると加工性が著しく劣化するので焼鈍温度の
上限をＡc3変態点とする。The annealing temperature of the continuous hot-dip galvanizing equipment of the continuous annealing or in-line annealing system is set to the Ac 1 transformation point or more and the Ac 3 transformation point or less. If the annealing temperature is lower than the Ac 1 transformation point, the second phase, that is, the low temperature transformation product, which is a feature of the present invention, cannot be obtained. Further, if annealing is performed at a temperature exceeding the Ac 3 transformation point, the workability is significantly deteriorated, so the upper limit of the annealing temperature is set to the Ac 3 transformation point.
【００３２】かくして、本発明によれば、降伏強度は低
く、著しく加工硬化し、高い塗装焼付硬化能をあわせ持
ち、平均ｒ値（深絞り特性）や伸び（張出特性）などの
加工性にも優れる鋼板を得ることができる。特に塗装焼
付硬化能に関しては、１０ｋｇｆ／ｍｍ2 程度までの高
いＢＨ量を必要に応じて付与することができ、かつ常温
非時効性を兼ね備えた冷延鋼板を提供することが可能で
ある。Thus, according to the present invention, the yield strength is low, the work hardening is remarkable, the paint bake hardenability is high, and the workability such as the average r value (deep drawing property) and the elongation (protrusion property) is improved. It is possible to obtain an excellent steel plate. In particular, regarding the coating bake hardenability, it is possible to provide a high BH amount of up to about 10 kgf / mm 2 as needed, and it is possible to provide a cold-rolled steel sheet that also has non-aging at room temperature.
【００３３】次に本発明を実施例にて説明する。Next, the present invention will be described with reference to examples.
【００３４】[0034]
実施例１ 表１に示す組成を有する鋼を溶製し、スラブ加熱温度１
２００℃、仕上温度９２０℃、巻取温度７００℃で熱間
圧延し、４．０ｍｍ厚の鋼帯とした。酸洗後８０％の圧
下率の冷間圧延を施し、０．８ｍｍ厚の冷延板とし、次
いで加熱速度１０℃／ｓ、均熱８１０〜９５０℃×５０
ｓ、６５０℃までの平均冷却速度５℃／ｓ、６５０℃か
ら室温までの平均冷却速度８０℃／ｓの連続焼鈍を行っ
た。さらに１．０％の圧下率の調質圧延をし、ＪＩＳ５
号引張試験片を採取し、引張試験に供した。引張試験結
果をまとめて表２に示す。Example 1 Steels having the compositions shown in Table 1 were melted and slab heating temperature 1
Hot rolling was performed at 200 ° C., finishing temperature of 920 ° C., and winding temperature of 700 ° C. to obtain a steel strip having a thickness of 4.0 mm. After pickling, cold rolling with a reduction rate of 80% is performed to obtain a cold rolled sheet having a thickness of 0.8 mm, then heating rate is 10 ° C / s, soaking is 810 to 950 ° C x 50.
s, continuous annealing was performed at an average cooling rate of 5 ° C./s up to 650 ° C., and an average cooling rate of 80 ° C./s from 650 ° C. to room temperature. Further, temper rolling with a reduction ratio of 1.0% is performed, and JIS5
The No. 10 tensile test piece was sampled and subjected to a tensile test. The results of the tensile test are summarized in Table 2.
【００３５】ここで、ＷＨ量は、圧延方向に２％の引張
歪を付加したときの加工硬化量であり、２％変形応力か
ら降伏応力（ＹＰ）を差し引いた量である。また、ＢＨ
量は２％予歪材に１７０℃×２０分の塗装焼付相当の熱
処理を施してから再度引張試験を行った場合の応力の増
加量（再引張試験時の下降伏応力から２％変形応力を差
し引いた値）である。また、２次加工脆化遷移温度は、
調質圧延した鋼板から直径５０ｍｍのブランクを打ち抜
き、ついで直径３３ｍｍのポンチでカップ成形し、これ
に種々の温度で落重試験を施した場合の延性−脆性遷移
温度である。Here, the WH amount is a work hardening amount when a tensile strain of 2% is applied in the rolling direction, and is an amount obtained by subtracting the yield stress (YP) from the 2% deformation stress. Also, BH
The amount is the amount of increase in stress when a tensile test is performed again after heat treatment equivalent to paint baking of 170% x 20 minutes for a 2% pre-strained material (2% deformation stress It is the value after subtraction). The secondary processing embrittlement transition temperature is
It is a ductile-brittle transition temperature in the case where a blank having a diameter of 50 mm is punched out from a temper-rolled steel sheet, then cup-formed with a punch having a diameter of 33 mm, and subjected to a drop weight test at various temperatures.
【００３６】表２から明らかなように、従来鋼の同レベ
ルの引張強度を有する鋼板と比較して、本発明鋼は従来
にはない高いＢＨ性を有し、かつ非常に優れた常温非時
効性を兼ね備えていることが分かる。このことはＭｎや
Ｃｒを用いて混合組織化した鋼板においては、Ｂを使用
して複合組織とした鋼板に比べて、好ましい転位密度を
有することが主な原因であると思われる。また、本発明
鋼は降伏強度が低く、面形状性に優れ、ＷＨ量やｒ値も
高い。したがって、例えば自動車の外内板パネルには好
適の材料である。As is apparent from Table 2, the steel according to the present invention has a high BH property that has not been obtained in the past and is extremely excellent in non-aging at room temperature, as compared with the steel sheet having the same level of tensile strength as the conventional steel. You can see that they have both sex. This is probably because the steel sheet having a mixed microstructure using Mn or Cr has a preferable dislocation density as compared with the steel sheet having a composite microstructure using B. Further, the steel of the present invention has low yield strength, excellent surface shape properties, and high WH amount and r value. Therefore, it is a suitable material for, for example, an outer panel of an automobile.
【００３７】実施例２ 表１の鋼３−２および３−４を用いて連続焼鈍における
均熱温度の影響について検討した。熱間圧延と冷間圧延
の条件は、実施例１と同様である。その後、１０℃／ｓ
で加熱し、８６０〜９３０℃において５０ｓ間保定した
後、６５０℃までの平均冷却速度５℃／ｓ、６５０℃か
らの平均冷却速度８０℃／ｓの連続焼鈍を行った。さら
に１．０％の圧下率の調質圧延をし、ＪＩＳ５号引張試
験片を採用し、引張試験に供した。引張試験結果をまと
めて表３に示す。Example 2 Using the steels 3-2 and 3-4 in Table 1, the effect of soaking temperature in continuous annealing was examined. The conditions of hot rolling and cold rolling are the same as in Example 1. After that, 10 ℃ / s
After heating at 860 to 930 ° C. for 50 s, continuous annealing was performed at an average cooling rate of 5 ° C./s up to 650 ° C. and an average cooling rate of 80 ° C./s from 650 ° C. Further, temper rolling was performed at a rolling reduction of 1.0%, and JIS No. 5 tensile test pieces were adopted and subjected to a tensile test. The results of the tensile test are summarized in Table 3.
【００３８】表３から明らかなように、本発明鋼は均熱
温度が変化しても安定して優れた材質特性が得られるこ
とが分かる。これに対して比較鋼３−４は均熱温度がわ
ずか変化するだけで強度が著しく変化し、またＢＨ量、
ｒ値も大きくばらついた。 実施例３ 表１の鋼３−１〜３−５および４−１〜４−４をスラブ
加熱温度１２００℃、仕上温度９３０℃、巻取温度７２
０℃の条件で熱間圧延し、３．８ｍｍ厚の鋼板とした。
酸洗後、冷間圧延して０．７５ｍｍ厚の冷延板とし、次
いで加熱速度１５℃／ｓで実施例１と同様の焼鈍温度ま
で加熱してから約７０℃／ｓで冷却し、４６０℃で慣用
の溶融亜鉛メッキを行い（浴中Ａｌ濃度は０．１１
％）、さらに加熱して５２０℃で２０ｓ間合金化処理
後、約２０℃／ｓで室温まで冷却した。得られた合金化
亜鉛メッキ鋼板についてメッキ外観、パウダリング性お
よびメッキ皮膜中のＦｅ濃度を測定した。これらの結果
を表４にまとめて示す。As is clear from Table 3, the steel of the present invention can stably obtain excellent material properties even when the soaking temperature changes. On the other hand, in Comparative Steel 3-4, the strength changes significantly with only a slight change in the soaking temperature, and the BH content,
The r value also varied greatly. Example 3 Steels 3-1 to 3-5 and 4-1 to 4-4 shown in Table 1 were heated at a slab temperature of 1200 ° C, a finishing temperature of 930 ° C, and a coiling temperature of 72.
It hot-rolled on condition of 0 degreeC, and set it as the 3.8-mm-thick steel plate.
After pickling, it is cold-rolled into a 0.75 mm-thick cold-rolled sheet, then heated to an annealing temperature similar to that in Example 1 at a heating rate of 15 ° C./s, and then cooled at about 70 ° C./s and then 460 Performed conventional hot dip galvanizing at ℃ (Al concentration in the bath is 0.11
%), Further heated and alloyed at 520 ° C. for 20 s, and then cooled to room temperature at about 20 ° C./s. With respect to the obtained galvannealed steel sheet, plating appearance, powdering property and Fe concentration in the plating film were measured. These results are summarized in Table 4.
【００３９】ここでメッキの外観は下記の基準で評価し
た。 ◎ ：面積率で１００％メッキが付着した状態 ○ ：面積率で９０％以上メッキが付着した状態 △ ：面積率で６０〜９０％メッキが付着した状態 × ：面積率で３０〜６０％メッキが付着した状態 ××：面積率で３０％以下しかメッキが付着していない
状態 ここでメッキ密着性（パウダリング）は１８０°の密着
曲げを行い、亜鉛皮膜の剥離状況を曲げ加工部に接着テ
ープを接着した後、これをはがしてテープに付着した剥
離メッキ量から判定した。評価は下記の５段階とした。Here, the appearance of the plating was evaluated according to the following criteria. ◎: A state where 100% of the area ratio is attached ○: A state where 90% or more of the area ratio is attached △: A state where 60 to 90% of the area ratio is attached ×: 30 to 60% of the area ratio Adhered state XX: State where the plating is adhered only by 30% or less in terms of area ratio. Here, the plating adhesion (powdering) is performed by 180 ° contact bending, and the peeling state of the zinc film is adhered to the bent portion with an adhesive tape. Was adhered on the tape and then peeled off, and the amount of peeling plating adhered to the tape was judged. The evaluation was made into the following 5 grades.
【００４０】１：剥離大 ２：剥離中 ３：剥離小
４：剥離微量 ５：剥離全くなし また、メッキ層中のＦｅ濃度は、Ｘ線回折によって求め
た。表４から明らかなように本発明鋼は、従来鋼と比較
してメッキ外観、パウダリング性が良好であり、合金層
中のＦｅ濃度も望ましい相と考えられているδ1 相のそ
れに相当する量となっている。これは、本発明において
はメッキ密着性を劣化させ合金化反応速度を遅くする
Ｐ、Ｂ、Ｓｉを低減し、ＭｎやＣｒを添加しているため
と考えられる。また、ＭｎやＣｒが添加されている場合
には、ある程度の量のＰやＳｉが含有されてもメッキ特
性を損なわないことが分かる。1: Large peeling 2: During peeling 3: Small peeling
4: Trace amount of peeling 5: No peeling at all The Fe concentration in the plating layer was determined by X-ray diffraction. As is clear from Table 4, the steel of the present invention has better plating appearance and powdering property than the conventional steel, and the Fe concentration in the alloy layer is equivalent to that of the δ 1 phase considered to be a desirable phase. It has become the amount. This is presumably because in the present invention, P, B, and Si that deteriorate plating adhesion and slow the alloying reaction rate are reduced, and Mn and Cr are added. Further, it can be seen that when Mn or Cr is added, the plating characteristics are not impaired even if a certain amount of P or Si is contained.
【００４１】[0041]
【表１】 [Table 1]
【００４２】[0042]
【表２】 [Table 2]
【００４３】[0043]
【表３】 [Table 3]
【００４４】[0044]
【表４】 [Table 4]
【００４５】[0045]
【発明の効果】以上の説明から明らかなように本発明に
よれば従来にはないＢＨ性と常温非時効性とを兼ね備え
た冷延鋼板を得ることができる。また、本発明鋼は、プ
レス成形性もきわめて良好であり、さらに溶融亜鉛メッ
キ特性にも優れているため防錆機能も発揮できる。その
結果、本発明鋼を自動車のボディやフレームなどに使用
すると板厚の軽減、すなわち車体の軽量化が可能となる
ので最近注目されている地球環境の保全にも本発明は大
きく寄与できる。このように本発明の産業上の意義はき
わめて大きい。As is apparent from the above description, according to the present invention, it is possible to obtain a cold-rolled steel sheet having both BH properties and non-aging at room temperature which have not been obtained in the past. Further, the steel of the present invention has extremely good press formability and also has excellent hot dip galvanizing properties, and therefore can exhibit a rust preventive function. As a result, when the steel of the present invention is used in the body or frame of an automobile, the thickness of the plate can be reduced, that is, the weight of the vehicle body can be reduced. Therefore, the present invention can greatly contribute to the conservation of the global environment, which has recently received attention. Thus, the industrial significance of the present invention is extremely great.
───────────────────────────────────────────────────── フロントページの続き (72)発明者 西村 邦夫 福岡県北九州市戸畑区飛幡町１番１号 新 日本製鐵株式会社八幡製鐵所内 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Kunio Nishimura Inventor Kunio Nishimura No. 1 Tobahata-cho, Tobata-ku, Kitakyushu, Fukuoka New Nippon Steel Corporation Yawata Works
Claims (5)
７０％、Ｓｉ：０．００１〜０．８％、Ｍｎ：０．３〜
４．０％、Ｐ：０．００３〜０．１５％、Ｓ：０．００
０５〜０．０１５％、Ａｌ：０．００５〜０．２０％、
Ｎ：０．０００３〜０．００６０％、残部Ｆｅおよび不
可避的不純物からなる組成にして、低温変態生成物とフ
ェライトとからなる混合組織を有することを特徴とする
優れた焼付硬化性と常温非時効性を兼備した冷延鋼板と
溶融亜鉛メッキ冷延鋼板。1. C: 0.0005-0.00, by weight.
70%, Si: 0.001-0.8%, Mn: 0.3-
4.0%, P: 0.003 to 0.15%, S: 0.00
05-0.015%, Al: 0.005-0.20%,
N: 0.0003 to 0.0060%, balance Fe and unavoidable impurities, and excellent bake hardenability and non-aging at room temperature, characterized by having a mixed structure of low-temperature transformation product and ferrite. Cold-rolled steel sheet and hot-dip galvanized cold-rolled steel sheet that have both excellent properties.
１．５を満たすＢを含有する請求項１記載の優れた焼付
硬化性と常温非時効性を兼備した冷延鋼板と溶融亜鉛メ
ッキ冷延鋼板。2. B: less than 0.0030% and B / N ≦
The cold-rolled steel sheet and the hot-dip galvanized cold-rolled steel sheet according to claim 1, which contain B satisfying 1.5, having both excellent bake hardenability and non-aging at room temperature.
求項１または２記載の優れた焼付硬化性と常温非時効性
を兼備した冷延鋼板と溶融亜鉛メッキ冷延鋼板。3. A cold-rolled steel sheet and a hot-dip galvanized cold-rolled steel sheet containing Cr: 0.01 to 3.0%, which have both the excellent bake hardenability and non-aging at room temperature.
度で熱間圧延の仕上げを行い、室温から７５０℃の温度
で巻取り、６０％以上の圧延率で冷間圧延を行い、連続
焼鈍における焼鈍温度をＡc1変態点以上かつＡc3変態点
以下とすることを特徴とする請求項１〜３のいずれかに
記載の優れた焼付硬化性と常温非時効性を兼備した冷延
鋼板の製造方法。4. A slab is hot-rolled at a temperature of (Ar 3 -100) ° C. or higher, wound at a temperature of room temperature to 750 ° C., cold-rolled at a rolling ratio of 60% or more, and continuously. The cold-rolled steel sheet having both excellent bake hardenability and non-aging at room temperature according to any one of claims 1 to 3, characterized in that the annealing temperature in the annealing is not less than Ac 1 transformation point and not more than Ac 3 transformation point. Manufacturing method.
度で熱間圧延の仕上げを行い、室温から７５０℃の温度
で巻取り、６０％以上の圧延率で冷間圧延を行い、焼鈍
温度をＡc1変態点以上かつＡc3変態点以下としたインラ
イン焼鈍型の溶融亜鉛メッキを施すことを特徴とする請
求項１〜３のいずれかに記載の優れた焼付硬化性と常温
非時効性を兼備した溶融亜鉛メッキ冷延鋼板の製造方
法。5. The slab is hot-rolled at a temperature of (Ar 3 -100) ° C. or higher, wound at a temperature of room temperature to 750 ° C., cold-rolled at a rolling ratio of 60% or more, and annealed. An excellent bake hardenability and normal temperature non-aging property according to any one of claims 1 to 3, wherein in-line annealing type hot dip galvanizing is performed at a temperature of Ac 1 transformation point or more and Ac 3 transformation point or less. A method of manufacturing a hot-dip galvanized cold-rolled steel sheet that also has the above.
Priority Applications (7)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP4232300A JPH0681081A (en) | 1992-08-31 | 1992-08-31 | Cold roller steel sheet and galvanized cold rolled steel sheet combining excellent baking hardenability and cold nonaging property as well and production thereof |
| EP93913564A EP0608430B1 (en) | 1992-06-22 | 1993-06-22 | Cold-rolled steel plate having excellent baking hardenability, non-cold-ageing characteristics and moldability, and molten zinc-plated cold-rolled steel plate and method of manufacturing the same |
| PCT/JP1993/000846 WO1994000615A1 (en) | 1992-06-22 | 1993-06-22 | Cold-rolled steel plate having excellent baking hardenability, non-cold-ageing characteristics and moldability, and molten zinc-plated cold-rolled steel plate and method of manufacturing the same |
| KR1019940700525A KR940702231A (en) | 1992-06-22 | 1993-06-22 | COLD ROLLED STEEL SHEET AND HOT DIP AINC-COATED COLD ROLLED STEEL SHEET HAVING EXCELLENT BAKE HARDENABILITY, NON-AGING PROPERTIES AND FORMABILITY, AND PROCESS FOR PRODUCING SAME) |
| DE69329236T DE69329236T2 (en) | 1992-06-22 | 1993-06-22 | COLD ROLLED STEEL SHEET WITH GOOD BURNING TEMPERATURE, WITHOUT COLD AGING AND EXCELLENT PORNABILITY, DIVER-COATED COLD ROLLED STEEL SHEET AND THEIR PRODUCTION PROCESS |
| KR1019940700525A KR970001411B1 (en) | 1992-06-22 | 1993-06-22 | Cold rolled steel sheet, hot-dip zinc-plated cold rolled steel sheet having excellent bake hardenability and aging characteristics, and a manufacturing method thereof |
| US08/196,098 US5470403A (en) | 1992-06-22 | 1993-06-22 | Cold rolled steel sheet and hot dip zinc-coated cold rolled steel sheet having excellent bake hardenability, non-aging properties and formability, and process for producing same |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP4232300A JPH0681081A (en) | 1992-08-31 | 1992-08-31 | Cold roller steel sheet and galvanized cold rolled steel sheet combining excellent baking hardenability and cold nonaging property as well and production thereof |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH0681081A true JPH0681081A (en) | 1994-03-22 |
Family
ID=16937056
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP4232300A Withdrawn JPH0681081A (en) | 1992-06-22 | 1992-08-31 | Cold roller steel sheet and galvanized cold rolled steel sheet combining excellent baking hardenability and cold nonaging property as well and production thereof |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0681081A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2001335887A (en) * | 2000-05-26 | 2001-12-04 | Kawasaki Steel Corp | Cold rolled steel sheet for deep drawing, excellent in strain aging hardenability, and manufacturing method |
| US6676774B2 (en) | 2000-04-07 | 2004-01-13 | Jfe Steel Corporation | Hot rolled steel plate and cold rolled steel plate being excellent in strain aging hardening characteristics |
| JP2007077510A (en) * | 2006-11-16 | 2007-03-29 | Jfe Steel Kk | High-strength high-ductility galvanized steel sheet excellent in aging resistance and its production method |
-
1992
- 1992-08-31 JP JP4232300A patent/JPH0681081A/en not_active Withdrawn
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6676774B2 (en) | 2000-04-07 | 2004-01-13 | Jfe Steel Corporation | Hot rolled steel plate and cold rolled steel plate being excellent in strain aging hardening characteristics |
| US6814819B2 (en) | 2000-04-07 | 2004-11-09 | Jfe Steel Corporation | Methods of manufacturing hot-dip galvanized hot-rolled and cold-rolled steel sheets excellent in strain age hardening property |
| US7396420B2 (en) | 2000-04-07 | 2008-07-08 | Jfe Steel Corporation | Hot-dip galvanized hot-rolled and cold-rolled steel sheets excellent in strain age hardening property |
| JP2001335887A (en) * | 2000-05-26 | 2001-12-04 | Kawasaki Steel Corp | Cold rolled steel sheet for deep drawing, excellent in strain aging hardenability, and manufacturing method |
| JP4524859B2 (en) * | 2000-05-26 | 2010-08-18 | Ｊｆｅスチール株式会社 | Cold-drawn steel sheet for deep drawing with excellent strain age hardening characteristics and method for producing the same |
| JP2007077510A (en) * | 2006-11-16 | 2007-03-29 | Jfe Steel Kk | High-strength high-ductility galvanized steel sheet excellent in aging resistance and its production method |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| A300 | Withdrawal of application because of no request for examination |
Free format text: JAPANESE INTERMEDIATE CODE: A300 Effective date: 19991102 |