JPH02149624A - Manufacture of high-tensile cold rolled steel sheet excellent in formability - Google Patents
Manufacture of high-tensile cold rolled steel sheet excellent in formabilityInfo
- Publication number
- JPH02149624A JPH02149624A JP30181688A JP30181688A JPH02149624A JP H02149624 A JPH02149624 A JP H02149624A JP 30181688 A JP30181688 A JP 30181688A JP 30181688 A JP30181688 A JP 30181688A JP H02149624 A JPH02149624 A JP H02149624A
- Authority
- JP
- Japan
- Prior art keywords
- rolled
- steel sheet
- cold
- formability
- steel
- 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.)
- Pending
Links
- 239000010960 cold rolled steel Substances 0.000 title claims abstract description 17
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 15
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 35
- 239000010959 steel Substances 0.000 claims abstract description 35
- 238000000137 annealing Methods 0.000 claims abstract description 23
- 238000010438 heat treatment Methods 0.000 claims abstract description 20
- 238000001953 recrystallisation Methods 0.000 claims abstract description 20
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 16
- 229910052698 phosphorus Inorganic materials 0.000 claims abstract description 8
- 239000000203 mixture Substances 0.000 claims abstract description 5
- 229910052757 nitrogen Inorganic materials 0.000 claims abstract description 5
- 239000012535 impurity Substances 0.000 claims description 3
- 238000005098 hot rolling Methods 0.000 abstract description 7
- 238000000034 method Methods 0.000 abstract description 7
- 238000005097 cold rolling Methods 0.000 abstract description 6
- 239000010962 carbon steel Substances 0.000 abstract 2
- 229910021384 soft carbon Inorganic materials 0.000 abstract 2
- 230000001105 regulatory effect Effects 0.000 abstract 1
- 230000035882 stress Effects 0.000 description 14
- 230000000694 effects Effects 0.000 description 12
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 10
- 239000006104 solid solution Substances 0.000 description 7
- 238000005728 strengthening Methods 0.000 description 7
- 238000012545 processing Methods 0.000 description 6
- 230000000052 comparative effect Effects 0.000 description 5
- 230000007423 decrease Effects 0.000 description 5
- 238000001816 cooling Methods 0.000 description 3
- 230000003647 oxidation Effects 0.000 description 3
- 238000007254 oxidation reaction Methods 0.000 description 3
- 239000002244 precipitate Substances 0.000 description 3
- 239000000047 product Substances 0.000 description 3
- 238000004381 surface treatment Methods 0.000 description 3
- 238000009864 tensile test Methods 0.000 description 3
- 238000012360 testing method Methods 0.000 description 3
- 229910005438 FeTi Inorganic materials 0.000 description 2
- 230000009471 action Effects 0.000 description 2
- 230000032683 aging Effects 0.000 description 2
- 230000008901 benefit Effects 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 230000002349 favourable effect Effects 0.000 description 2
- 238000005554 pickling Methods 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 238000011160 research Methods 0.000 description 2
- 229920006395 saturated elastomer Polymers 0.000 description 2
- 238000002791 soaking Methods 0.000 description 2
- 229910001335 Galvanized steel Inorganic materials 0.000 description 1
- 238000004220 aggregation Methods 0.000 description 1
- 230000002776 aggregation Effects 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 238000005275 alloying Methods 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 238000005261 decarburization Methods 0.000 description 1
- 230000002542 deteriorative effect Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000008397 galvanized steel Substances 0.000 description 1
- 238000005246 galvanizing Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 238000010791 quenching Methods 0.000 description 1
- 230000000171 quenching effect Effects 0.000 description 1
- 230000002787 reinforcement Effects 0.000 description 1
- 230000003014 reinforcing effect Effects 0.000 description 1
- 238000005096 rolling process Methods 0.000 description 1
- 238000007788 roughening Methods 0.000 description 1
- 238000005185 salting out Methods 0.000 description 1
- 238000005204 segregation Methods 0.000 description 1
- 238000005245 sintering Methods 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
- 238000004804 winding Methods 0.000 description 1
Landscapes
- 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、高強度でかつプレス成形性にすぐれた高強度
冷延鋼板の製造法に関する。DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for manufacturing a high-strength cold-rolled steel sheet that has high strength and excellent press formability.
本発明により製造される冷延鋼板は適宜表面処理やプレ
ス加工をした後、例えば自動車、家電製品、ｆｊＡ構造
物などに使用されるのであり、特にそれらに要求される
造形性と強度を同時に付与することが可能である。その
結果、それらの製品の薄肉化すなわち軽量化が達成でき
る。After the cold-rolled steel sheets produced by the present invention are subjected to appropriate surface treatment and press working, they are used, for example, in automobiles, home appliances, FJA structures, etc. In particular, the cold-rolled steel sheets manufactured by the present invention can be used to simultaneously provide formability and strength required for these products. It is possible to do so. As a result, these products can be made thinner or lighter.
（従来の技術）
製鋼段階で十分に脱炭処理をして極低炭素としてからＴ
ｉを添加した極低炭素Ｔｉ添加鋼をベースにＳｉｂ Ｍ
ｎｓ Ｃ’やＰを添加して強度を上げた高張力冷延鋼板
については多くの提案がすでにある。(Conventional technology) After thorough decarburization treatment at the steel manufacturing stage to achieve extremely low carbon
Sib M based on ultra-low carbon Ti-added steel with i added
There have already been many proposals regarding high-strength cold-rolled steel sheets with increased strength by adding ns C' and P.
たとえば、特公昭５７−５７９４５号においては上記極
低炭素Ｔｉ添加鋼に多量のＰを添加した冷延鋼板が開示
されている。この場合においてはＭｎは０．９０％未満
しか含まれていないこともあり、得られるｒ値は１．６
〜１．９が限界になっている。また、Ｎ。For example, Japanese Patent Publication No. 57-57945 discloses a cold-rolled steel sheet in which a large amount of P is added to the ultra-low carbon Ti-added steel. In this case, the Mn content may be less than 0.90%, and the resulting r value is 1.6.
~1.9 is the limit. Also, N.
Ｓ含有量について、さらには２次加工脆性について何ら
言及していない。There is no mention of S content or secondary processing embrittlement.
また特公昭５８−２９１２９号においては上記極低炭素
Ｔｉ添加鋼に多量のＭｎを単独添加した例が開示されて
いるが、この場合も強度の割りには高いｒ値が得られ難
く、その結果、連続焼鈍後の冷却を水焼き入れにする必
要がＢＥしており、実用性がとぼしいものとなっている
。In addition, Japanese Patent Publication No. 58-29129 discloses an example in which a large amount of Mn is added alone to the ultra-low carbon Ti-added steel, but in this case too, it is difficult to obtain a high r value considering the strength, and as a result, However, it is necessary to use water quenching for cooling after continuous annealing, making it impractical.
その他、上記極低炭素Ｔｉ添加鋼にＳｉを添加するもの
や、Ｃ「を添加するものなどが開示されているが実用的
には鋼板表面の酸化が問題となりなかなか実用化されて
いないのが実情である。Other methods have been disclosed, such as those in which Si is added to the ultra-low carbon Ti-added steel and those in which C is added, but the reality is that oxidation on the surface of the steel plate becomes a problem and has not been put into practical use. It is.
一方、このような極低炭素Ｔｉ添加鋼に合金元素を添加
していくと２次加工脆性が生じやすくなることは良く知
られており、そのために一般にはＢを複合添加し２次加
工脆性を防止する手段がとられている。しかし、多量の
Ｂの添加はスラブの割れの原因になったり、またそのよ
うな多量のＢの添加を確実に行うには困難があり、操業
上の不安定性をもたらすことがあるなど、２次加工脆性
の防止の決定的手段とはなっていない。On the other hand, it is well known that adding alloying elements to ultra-low carbon Ti-added steel tends to cause secondary work embrittlement, and for this reason, B is generally added in combination to reduce secondary work embrittlement. Measures are being taken to prevent this. However, adding a large amount of B can cause cracks in the slab, and it is difficult to reliably add such a large amount of B, which may lead to operational instability. It is not a definitive means of preventing processing embrittlement.
（発明が解決しようとする問題点）
以上のことから、本発明者らにおいてはもちろ、ｌ−’
＋ 、Ｅ ｕニｈ （ｔ’ テも、引張強サカ３８ ｋ
ｇｆ／＋ｕ＋２以上、降伏応力は（引張強さ−１２ｋｇ
ｆ／ｍｓ”）以下、ｒ値１．８以上でかつ２次加工脆性
の生じにくい冷延鋼４反およびそれを通常の連ＶＥ焼Ｓ
屯でかつ（氏コストの合金添加で製造する方法が長年に
わたって研究され、希求されてきた。(Problems to be Solved by the Invention) From the above, the inventors of the present invention understand that l-'
+ , E u ni h (t' te also has a tensile strength of 38 k
gf/+u+2 or more, the yield stress is (tensile strength -12kg
4 rolls of cold rolled steel with an r value of 1.8 or higher and less likely to cause secondary work brittleness (f/ms"), and a regular continuous VE sintering process.
For many years, a method of manufacturing by adding alloys at a low cost has been researched and desired.
したがって、本発明の目的とするところは、引張強さが
３８ ｋｇｆ／ｍｓ＋”以上、降伏応力が（引張強さ１
２ ｋｇｆ／ａｍ”）以下、ｒ値１．８以上かつ２次加
工脆性の生じにくい成形性にすぐれた高張力冷延鋼板の
製造法を提供することである。Therefore, the object of the present invention is to have a tensile strength of 38 kgf/ms+" or more and a yield stress of (tensile strength 1
2 kgf/am'') or less, an r value of 1.8 or more, and a high-strength cold-rolled steel sheet with excellent formability that is unlikely to cause secondary work brittleness.
（問題点を解決するための手段）
本発明者らは、かかる目的達成のため、前述の極低炭素
Ｔ＋添加鋼に着目して鋭意研究を続けてきた。(Means for Solving the Problems) In order to achieve the above object, the present inventors have continued intensive research focusing on the above-mentioned ultra-low carbon T+ added steel.
ここに、本発明者らにより見い出された知見は、極低炭
素Ｔｉ添加鋼をベースに適債のＭｎとＰを共存させると
、冷間圧延、焼鈍後の引張強さが上昇するだけでなく同
時にｒ値が著しく向上し、さらに少量の固溶Ｃが残存す
ることである。このような固溶Ｃの残存によって２次加
工脆性が効果的に防止される。Here, the knowledge discovered by the present inventors is that when an appropriate amount of Mn and P coexist in ultra-low carbon Ti-added steel, not only does the tensile strength after cold rolling and annealing increase. At the same time, the r value is significantly improved and a small amount of solid solution C remains. The residual solid solution C effectively prevents secondary work brittleness.
これは？！、Ｍｎ５Ｐ、 ＳとＣの間の相互作用に起因
するもので、例えば、ＭｎとＰが共存していない鋼にお
いてはＴｉＣとＭｎＳがそれぞれ安定な析出物として形
成されているため、ＴＩ≧４ （Ｃ＋ １２／１４Ｎ）
のＴｉが添加されていれば固溶Ｃは残存しないが、多量
のＭｎとＰが共存しているとＴｉＣの一部が分解され、
鋼中にはＦｅＴｉＰ、 ＭＩＩＳ、 ｉｔｓ、 ＭｎＰ
などの析出物が形成され、固溶状態のＣが存在すること
になるためと思われる゛、このような状態で再結晶焼鈍
させるとこのｉＨｔの固溶Ｃのためｒ値に好ましい再結
晶集合組織が発達し、ｒ値が著しく向上する上にそのよ
うな固溶Ｃは焼鈍後の鋼板中にも残存し、結晶粒界を強
化し２次加工脆性を防止するとともに、少量の焼付硬化
性を発揮することも可能となる。this is? ! , Mn5P, S and C. For example, in steel where Mn and P do not coexist, TiC and MnS are each formed as stable precipitates, so TI≧4 ( C+ 12/14N)
If a large amount of Ti is added, no solid solution C will remain, but if a large amount of Mn and P coexist, part of the TiC will be decomposed,
FeTiP, MIIS, its, MnP in steel
This is thought to be due to the formation of precipitates such as, and the presence of C in a solid solution state.If recrystallization annealing is performed in such a state, the recrystallization aggregation favorable for the r value will occur due to the solid solution C of iHt. The structure develops, and the r value improves markedly. In addition, such solid solution C remains in the steel sheet after annealing, strengthens grain boundaries and prevents secondary work brittleness, and also improves a small amount of bake hardenability. It is also possible to demonstrate.
本発明者らはそれらの知見に基づき、特開昭６３−１９
０１４１号に開示する冷延鋼板およびその製造法を出願
したが、さらに研究を重ねた結果、Ｎｂの複合添加を行
いかつ再結晶焼鈍の際の加熱速度を特定範囲内に限定す
るとＴｉ１ｉｌの低減が可能となり、それだけのコスト
低下、表面処理法の改善がなされることが判明し、本発
明に至った。Based on those findings, the present inventors
No. 0141 was filed for the cold-rolled steel sheet and its manufacturing method, but as a result of further research, Ti1il could be reduced by adding Nb in combination and limiting the heating rate during recrystallization annealing within a specific range. It has been found that this method has become possible, and that the cost can be reduced and the surface treatment method improved accordingly, leading to the present invention.
なお、Ｎｂ添加の効果のメカニズムは不明であるが、Ｎ
ｂはＣやＮと結合し、上記ＦｅＴｉ Ｐ 、 Ｔｉ Ｓ
の形成を助け、このような化合物の析出と再結晶のスピ
ードが競争するように再結晶焼鈍時の加熱速度が！Ｉ！
整されていると高いｒ値を示す再結晶集合組織が焼鈍の
加熱時に発達するものと思われる。Note that although the mechanism of the effect of Nb addition is unknown,
b combines with C or N, and the above FeTi P , Ti S
Heating rate during recrystallization annealing so that the precipitation and recrystallization speed of such compounds compete! I!
It is thought that a recrystallized texture that exhibits a high r value when well-organized develops during heating during annealing.
さらに、上記の知見をベースに安価な強化元素であるＳ
ｉを適量添加したところ上記の効果は失われず容易に高
強度が得られる上、ＭｎｌとＰｇが適当な範囲にある綱
ではＳｉによる酸化の問題が軽減され冷延鋼板や亜鉛め
っき鋼板の製造に有利なことも同時に見い出した。Furthermore, based on the above knowledge, S, which is an inexpensive reinforcing element,
When an appropriate amount of i is added, the above effects are not lost and high strength can be easily obtained, and the problem of oxidation due to Si is alleviated in steels with Mnl and Pg in appropriate ranges, making it suitable for the production of cold-rolled steel sheets and galvanized steel sheets. At the same time, we found some advantages.
ここに、本発明の要旨とするところは
重量％で、
Ｃ： ｏ、ｏｏｏｓ〜０．０１２％、Ｎ：０．０００５
〜０．００８％、ｓｏｌ、ＡＱ： ０．０８％以下、
Ｓ： ０．０１０％以下、Ｔｉ： ０．００５〜０．０
４％、 Ｎｂ： ０．００３〜０．０３％、を含み、
さらにＭｎ： ０．９０６Ａ超、３．０％以下およびＰ
：０．０５〜０．１５％を複合添加し、
ならびに所望によりさらにＢ ：Ｏ，０ＯＯ１〜０．０
００５％およびＭｏ：０．０３〜０．２５％の１種また
は２種を添加し、
残部Ｆｅおよび不可避的不純物
よりなる組成を有する鋼を熱間圧延し、次いで冷間圧延
そして５００℃から７００℃までの平均加熱速度をｌＯ
〜１００℃／Ｓにて再結晶焼鈍をすることを特徴とする
成形性の良好な高張力冷延鋼板の製造法である。Here, the gist of the present invention is in weight%, C: o,ooos~0.012%, N: 0.0005
~0.008%, sol, AQ: 0.08% or less,
S: 0.010% or less, Ti: 0.005 to 0.0
4%, Nb: 0.003 to 0.03%, further Mn: more than 0.906A, 3.0% or less, and P
:0.05 to 0.15% is added in combination, and if desired, further B :O,0OO1 to 0.0
005% and Mo: 0.03 to 0.25%, and the remainder is Fe and unavoidable impurities. The steel is hot rolled, then cold rolled, and then rolled from 500°C to 700°C. The average heating rate to °C is lO
This is a method for producing a high-strength cold-rolled steel sheet with good formability, which is characterized by recrystallization annealing at ~100° C./S.
本発明の好適態様にあっては、さらにＳｉ： ０．０２
〜０．６０％を添加してもよい。In a preferred embodiment of the present invention, Si: 0.02
~0.60% may be added.
（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。なお、本
明細四において「％」はとくにことわりがない限り、「
重■％」である。(Function) Here, the reason why the steel composition and manufacturing conditions are limited as described above in the present invention will be further explained. In addition, in this specification 4, "%" means "unless otherwise specified".
%".
Ｃ：
Ｃは鋼中に必然的に含有される。前述の粒界強化に必要
なＣは０．０００３％程度であるが、Ｃを低下させるの
はコストアップにつながることから、下限を０．０００
５％にした。Ｃが多くなると強化には寄与するが必要と
されるＴｉ１ｉｌが増してコストアップになる。したが
って、本発明にあってＣの上限を０．０１２％とした。C: C is naturally contained in steel. The C required for the grain boundary strengthening mentioned above is about 0.0003%, but since reducing C leads to an increase in cost, the lower limit is set to 0.0003%.
It was set to 5%. An increase in C contributes to strengthening, but the required Ti1il increases, leading to an increase in cost. Therefore, in the present invention, the upper limit of C is set to 0.012%.
Ｎ：
Ｎは少ない方が望ましい、しかし、その低減にはコスト
がかかるため、下限をｏ、ｏｏｏｓ％とじた。一方、余
り多いと多量のＴｉやＮｂ添加が必要なことから上限を
０．００８％とした。N: It is desirable that N be small, but reducing it is costly, so the lower limit is set to o,oos%. On the other hand, if it is too large, a large amount of Ti or Nb needs to be added, so the upper limit was set at 0.008%.
ｓｏｌ、△Ｑ：
脱酸調整に添加される。必ずしも添加しなくてもよいが
その時はＴｉやＮｂの添加歩留が低下する。ＳＯｌ、Ａ
Ｑが多いとコストアンプになるので上限を０．０８％と
した。sol, ΔQ: Added to deoxidation adjustment. Although it is not always necessary to add Ti and Nb, in that case the addition yield of Ti and Nb decreases. SOL,A
If Q is large, the cost will be increased, so the upper limit was set to 0.08%.
Ｓ： 本発明においては特に低下するのが望ましい。S: In the present invention, it is particularly desirable to reduce the amount.
ｓｌが０．０１０％を超えるとＭｎＳが形成され、これ
が加工性を劣化させる上に前述のＭｎＰが形成されにく
くなる。When sl exceeds 0.010%, MnS is formed, which deteriorates processability and makes it difficult to form the above-mentioned MnP.
Ｔｌ： Ｔｉは低降伏応力と高いｒ値を得るために添加される。Tl: Ti is added to obtain low yield stress and high r value.
その添加量は０．００５％未満では固溶炭素や固溶Ｎが
多くなり降伏応力が高く、かつ低いｒ値しか得られない
。If the amount added is less than 0.005%, solute carbon and solute N will increase, yield stress will be high, and only a low r value will be obtained.
一方、０．０４％超添加してもその効果が飽和するだけ
でコストアンプになりかつ鋼板の表面処理性を劣化させ
る。On the other hand, even if more than 0.04% is added, the effect is only saturated, resulting in a cost increase and deteriorating the surface treatment properties of the steel sheet.
Ｎｂ：
ＮｂもＴＩと同様の作用がある。特に上記の様にＴｉ％
を限定した場合、ＮｂはＴｉと相互作用をもち、Ｔｉの
作用を効果的に発揮させる。Nb: Nb also has the same effect as TI. Especially as mentioned above, Ti%
When Nb is limited, Nb interacts with Ti and effectively exerts the action of Ti.
このためには０．００３〜０．０３％の添加が有効であ
る。０．００３％未満では降伏応力が高くなりかつｒ値
も低下する。 ０．０３０％超では再結晶温度が高くな
り延性が低下してしまう。For this purpose, addition of 0.003 to 0.03% is effective. If it is less than 0.003%, the yield stress becomes high and the r value also decreases. If it exceeds 0.030%, the recrystallization temperature becomes high and the ductility decreases.
Ｍｎ： これは、ＭｎＳ、ＭｎＰを形成させるめに必要である。Mn: This is necessary to form MnS and MnP.
０．９０％以下ではその形成が不十分で、高いｒ値と
粒界強化が得られない、一方、３．０％を超えるとＭｎ
Ｐが形成され過ぎ、却ってｒ値が低下する。したがって
、０．９０％超、３．０％以下に限定した。好ましくは
、１．２〜２．０％である。If it is less than 0.90%, its formation is insufficient and high r value and grain boundary strengthening cannot be obtained.On the other hand, if it exceeds 3.0%, Mn
Too much P is formed, and the r value actually decreases. Therefore, it was limited to more than 0.90% and 3.0% or less. Preferably it is 1.2 to 2.0%.
ＰもＭｎ Ｐ 、 ＦｅＴｉ Ｐを形成させるために必
要である。特にＴｉＣよりＴｉをｈ１１提しＣを固溶さ
せる作用がある。 Ｏ，ＯＳ％未満ではそのような効果
が不足で高いｒ値と粒界強化が達成できない。P is also necessary to form Mn P and FeTi P. In particular, it has the effect of displacing Ti more than TiC and dissolving C as a solid solution. If the content is less than O,OS%, such effects are insufficient and a high r value and grain boundary strengthening cannot be achieved.
方、０６１５％を超えると鋼中でのＰ偏析が多くなり、
スラブの割れなどが生じやすくなる。したがって、０．
０５〜０．１５％に限定した。On the other hand, when it exceeds 0.615%, P segregation in the steel increases,
Slab cracks are more likely to occur. Therefore, 0.
It was limited to 0.05 to 0.15%.
Ｓｉ：
Ｓｉは所望により添加され、本発明において規定する上
述のようなＭｎｌとＰｆｆｉとの範囲内にあっては、Ｓ
ｉは０．０２〜０．６０％添加すれば十分であって、酸
化の問題は起こらない。Si: Si is added as desired, and within the range of Mnl and Pffi as defined above in the present invention, S
It is sufficient to add i in an amount of 0.02 to 0.60%, and no problem of oxidation occurs.
Ｂ：
Ｂは粒界に偏析し粒界を強化する作用を有する０本発明
においてはＣが粒界に偏析し粒界を強化し、２次加工脆
性を防止することを特徴としているが、必要に応じ少量
のＢを複合添加しても本発明の効果を減することはなく
、粒界の強化を確実にするため必要に応じ添加してもよ
い、この場合Ｂの添加量は、０．０００１％未満では意
味がなく、またｏ、ｏｏｏｓ％超では添加コストの上昇
やスラブ割れの原因となるため、０．０００１〜０．０
００５％とした。本発明では、従来の場合と比較してこ
のように少量のＢでよいことが一つの特徴である。B: B has the effect of segregating at grain boundaries and strengthening them. The present invention is characterized by C segregating at grain boundaries, strengthening the grain boundaries, and preventing secondary work brittleness, but it is not necessary. Even if a small amount of B is added in combination, the effect of the present invention will not be reduced, and it may be added as necessary to ensure grain boundary reinforcement. In this case, the amount of B added is 0. If it is less than 0.0001%, it is meaningless, and if it exceeds o,oos%, it will increase the addition cost and cause slab cracking, so 0.0001 to 0.0
005%. One of the features of the present invention is that a smaller amount of B is required compared to the conventional case.
ＭＯ：
？ＩＯも粒界を強化させる作用を有する。さらに粒界を
強化し、２次加工脆性を確実に防止したい場合、必要に
応じて添加される。この添加量は０．０３％以上必要で
ある。ただし−〇は高価なのでその効果が飽和する０、
２５％を上限とした。MO: ? IO also has the effect of strengthening grain boundaries. Furthermore, if it is desired to strengthen grain boundaries and reliably prevent secondary processing brittleness, it is added as necessary. This addition amount needs to be 0.03% or more. However, −〇 is expensive, so its effect is saturated, 0,
The upper limit was set at 25%.
この他に必要強度に応じ六「などを適量（１％以下）添
加してもよい。In addition to this, an appropriate amount (1% or less) of 6' etc. may be added depending on the required strength.
次に、製造法における条件限定の理由について述べる。Next, the reason for limiting the conditions in the manufacturing method will be described.
熱間圧延、冷間圧延、焼鈍：
熱間圧延は特に制限なく、慣用のそれを行えばよい０例
えば７００℃以上で９５０℃以下で５０％以上の加工を
行う。Hot rolling, cold rolling, annealing: Hot rolling is not particularly limited, and any conventional method may be used.For example, 50% or more processing is performed at 700° C. or higher and 950° C. or lower.
本発明にあって、熱間圧延−冷間圧延−焼鈍が行われる
が、熱間圧延終了後の巻取温度は通常のように７００℃
〜常温でよい、冷間圧延も同様である。In the present invention, hot rolling, cold rolling, and annealing are performed, but the coiling temperature after hot rolling is usually 700°C.
The same applies to cold rolling, which may be carried out at room temperature.
しかしながら、再結晶焼鈍の加熱速度は限定されなけれ
ばならない。However, the heating rate for recrystallization annealing must be limited.
すなわち、その加熱の５００〜７００℃までの平均加熱
速度を１０〜ｂ
通常の連続焼鈍では加熱速度は２〜ｂ
るのでそれより速くする必要がある。実際にはラジアン
トチューブの能力を増すとか直火加熱をするとかが採用
される。That is, the average heating rate for heating from 500 to 700°C needs to be faster than 10-b.In normal continuous annealing, the heating rate is 2-b. In reality, increasing the capacity of radiant tubes or using direct flame heating are adopted.
上記限定の意味は冷間圧延組織が再結晶する時の加熱速
度、実際には再結晶のスピードを制御し再結晶時にＦｅ
Ｔｉ Ｐなどの析出物を作用させることがｒ値に好まし
い再結晶集合ｍｍを得るために必要との知見によってい
る。The meaning of the above limitation is the heating rate when the cold-rolled structure recrystallizes, in fact, the recrystallization speed is controlled and Fe is
This is based on the knowledge that the action of precipitates such as Ti 2 P is necessary in order to obtain a recrystallization set mm favorable to the r value.
再結晶の開始温度は一般に約５６０℃、完了は約７００
℃である。したがって再結晶が開始するより前の段階か
ら完了までの温度範囲での加熱速度が制御される。The starting temperature for recrystallization is generally about 560°C, and the completion temperature is about 700°C.
It is ℃. Therefore, the heating rate is controlled in the temperature range from the stage before recrystallization begins until its completion.
１０℃／Ｓ未満では再結晶のスピードが遅すぎ裔いｒ値
が得られない、１００℃／Ｓ超では再結晶のスピードが
速すぎ集合ｍｒａのｕＪＴａＩがなされる余裕がなくや
はり高いｒ値が得られない、好ましくは２０〜ｂ
なお、焼鈍は連続焼鈍が望ましい、その場合の最高焼鈍
温度は７００〜９２０℃が好ましい、連続溶融亜鉛めっ
きラインで連続焼鈍する場合も同様である。この後適当
量の調質圧延を行っ、て製造される。If it is less than 10°C/S, the recrystallization speed is too slow and a descendant r value cannot be obtained, and if it exceeds 100°C/S, the recrystallization speed is too fast and there is no room for uJTaI of the aggregated mra to be formed, resulting in a high r value. Not obtained, preferably 20 to b. Note that continuous annealing is desirable, and in that case, the maximum annealing temperature is preferably 700 to 920°C. The same applies to continuous annealing in a continuous hot-dip galvanizing line. After this, an appropriate amount of temper rolling is performed to produce the product.
次に、実施例によって本発明を詳述する。Next, the present invention will be explained in detail by way of examples.
実施例１
第１表
第１表に示す組成をベースにし、これにＴｉとＮｂ添加
量が変動した鋼を溶製し、スラブ加熱温度１１５０℃、
仕上温度９００℃、巻取温度５００℃の条件下での熱間
圧延により３．２１厚のＩ仮に仕上げた。Example 1 Based on the composition shown in Table 1, steel with varying amounts of Ti and Nb added was melted, and the slab heating temperature was 1150°C.
A 3.21-thick I tent was finished by hot rolling under conditions of a finishing temperature of 900°C and a winding temperature of 500°C.
酸洗後、これらを０ 、８ｍｍ厚まで圧下率７５％で冷
間圧延し、次いで５００〜７００℃間の平均加熱速度２
０℃／ｓｅｃ、均熱８５０℃×４０秒、冷却速度２０℃
／ｓｅｃの連続焼鈍により再結晶焼鈍を行った。加熱は
直火加熱で行った。After pickling, they were cold rolled to a thickness of 0.8 mm at a reduction rate of 75%, and then heated at an average heating rate of 2 between 500 and 700 °C.
0℃/sec, soaking at 850℃ x 40 seconds, cooling rate 20℃
Recrystallization annealing was performed by continuous annealing at /sec. Heating was performed using direct heat.
このようにし得た再結晶焼鈍材よりＪＩＳ Ｓ号試験片
を採取し、引張試験を行い「値（３方向平均値）を測定
した。A JIS No. S test piece was taken from the recrystallized annealed material obtained in this way, and a tensile test was performed to measure the value (average value in three directions).
結果を第１図および第２図にまとめて示す。The results are summarized in FIGS. 1 and 2.
第１図は、Ｔｉ％、Ｎｂ％とｒ値との関係を示すグラフ
で本発明の範囲では高いｒ値が得られることがわかる。FIG. 1 is a graph showing the relationship between Ti%, Nb% and r value, and it can be seen that a high r value can be obtained within the range of the present invention.
本発明による降伏応力、ｒ値および引張強さの各データ
点を、従来製造されていた高張力冷延鋼板のｒ値、降伏
応力および引張強さの関係図上に示すと第２図のように
なり、本発明によれば同一強度レベルの従来の鋼板にく
らべｒ値が高く降伏応力が低くプレス成形性が良好な鋼
板が得られることがわかる。The data points of the yield stress, r value, and tensile strength according to the present invention are shown in the relationship diagram of the r value, yield stress, and tensile strength of conventionally manufactured high-tensile cold rolled steel sheets as shown in Figure 2. It can be seen that according to the present invention, a steel plate with a higher r value, lower yield stress, and better press formability than a conventional steel plate with the same strength level can be obtained.
実施例２
第２表に示す成分組成の鋼を溶製し、スラブとなした後
１１００℃にて１時間加熱後直ちに熱間圧延を開始し、
仕上温度８８０°Ｃにて３．２１厚の熱延鋼板に仕上げ
た。酸洗後、これらを０ 、８ｍｍ厚まで冷間圧延し、
次いで、５００〜７００℃間の平均加熱速度０．１〜２
５０℃／ｓｅｃ、均熱８２０℃Ｘ６０秒、冷却速度４０
℃／ｓｅｃの連続焼鈍により再結晶焼鈍を行った。Example 2 Steel having the composition shown in Table 2 was melted and made into a slab. After heating at 1100°C for 1 hour, hot rolling was immediately started.
A hot-rolled steel plate with a thickness of 3.21 mm was finished at a finishing temperature of 880°C. After pickling, these were cold rolled to a thickness of 0.8 mm,
Then, the average heating rate between 500 and 700°C is 0.1 to 2
50℃/sec, soaking at 820℃ x 60 seconds, cooling rate 40
Recrystallization annealing was performed by continuous annealing at °C/sec.
その後、伸び率０．３％の調質圧延を行いそれよりＪＩ
Ｓ Ｓ号引張試験片を採取し引張試験を行った。After that, it is temper rolled with an elongation rate of 0.3% and then JI
A No. SS tensile test piece was taken and a tensile test was conducted.
ここで時効指数は８％の予歪を加えた後、１００℃、１
ｈｒの時効処理をし、次いで再引張を行いこの時の降
伏応力の上昇量から求めた。鋼板中に固溶炭素量が多い
とこの時効指数が高い値を示すことがわかっている。Here, the aging index is 100℃, 1 after adding 8% prestrain.
The specimen was aged for hr, then re-stretched, and the yield stress was determined from the increase in yield stress at this time. It is known that this aging index exhibits a high value when the amount of solid solute carbon in the steel sheet is large.
この他に調質圧延をしたｗＪ板より直径６６ｓ＋ｍのブ
ランクを打抜き次いで直径３３ｆｆｉ１１のポンチでカ
ップ状に深絞りを行い、これに対し種々の温度で薄型テ
ストを行い何度で脆性破壊をするかを調べた。In addition, blanks with a diameter of 66s+m are punched out from temper-rolled WJ plates, and then deep drawn into cup shapes using a punch with a diameter of 33FFI11, and thinner tests are conducted at various temperatures to determine the temperature at which brittle fracture occurs. I looked into it.
これが２次加工脆性テストの方法である。This is the method of secondary processing brittleness test.
第２表にはこれらの結果もまとめて示されている。Table 2 also summarizes these results.
本発明による鋼板は引張強さが３８ ｋｇｆ／ａｒｍ”
以上でかつ降伏応力が（引張強さ−１２ｋｇｒ／ｍ＋”
）以下であり、また強度の割りに伸びがよ＜、ｒ値も１
．８以上、多くは２．０以上で非常に高いことがわかる
。The steel plate according to the present invention has a tensile strength of 38 kgf/arm”
or more and the yield stress is (Tensile strength - 12kgr/m+"
) or less, and the elongation is good considering the strength.The r value is also 1.
．． It can be seen that the scores are very high, with scores of 8 or higher, and most of them 2.0 or higher.
これに対し、比較鋼１．２．６は加熱速度が不適切なた
めｒ値が低くそして比較１１５はＴｉの添加量が不足の
ため降伏応力が高くｒ値が低かった。On the other hand, Comparative Steel 1.2.6 had a low r value due to an inappropriate heating rate, and Comparative Steel 115 had a high yield stress and low r value due to an insufficient amount of Ti added.
比較鋼１６はＭｎが不足しているためｒ値が低い。Comparative Steel 16 has a low r value because it lacks Mn.
比較例１７はＰが少ないためｒ値が低い。Comparative Example 17 has a low r value due to low P content.
また、２次加工脆性については本発明例ではいずれも一
４０℃以下であり実用上問題ないが、特に比較鋼１日は
Ｎｂ含を量が多すぎるために、前述の如き理由により、
延性が低下し、２次加工脆性遷移点度が一１０℃となっ
て本発明の目的を達し得ない。Regarding secondary work embrittlement, in all of the examples of the present invention, the temperature is -40°C or less, so there is no practical problem, but in particular, the comparative steel 1 day contains too much Nb, so for the reasons mentioned above,
The ductility decreases and the secondary processing brittleness transition point degree becomes 110°C, making it impossible to achieve the object of the present invention.
（発明の効果）
このように、本発明によれば、成形性にすぐれた高張力
鋼が低コストの製造法によって得られるのであり、コス
トの低減そして製造ラインの面素化が強く求められてい
る今日的状況からはその効果は著しいものと云わざるを
得ない。(Effects of the Invention) As described above, according to the present invention, high-strength steel with excellent formability can be obtained by a low-cost manufacturing method, and there is a strong demand for cost reduction and surface roughening of the manufacturing line. Considering the current situation, it cannot be said that the effect is remarkable.
特に、本発明により製造される鋼板は自動車のフレーム
、その他主要構造部材メンバー類に使用した場合、車体
重量の軽減に大きく寄与するものであり、その産業上の
意義、利益は大きい。In particular, when the steel plate manufactured according to the present invention is used for automobile frames and other major structural members, it greatly contributes to reducing the weight of the vehicle, and has great industrial significance and benefits.
第１図は、Ｎｂ％、Ｔｉ％とｒ値および引張強さとの関
係を示すグラフ：および
第２図は、本発明にかかる鋼板の降伏応力、ｒ値および
引張強さの各データ点を、従来製造されていた高張力冷
延鋼板のｒ値、降伏応力および引張強さの関係図上に示
すグラフである。FIG. 1 is a graph showing the relationship between Nb%, Ti%, r value, and tensile strength; and FIG. 2 is a graph showing each data point of yield stress, r value, and tensile strength of the steel plate according to the present invention. It is a graph shown on the relationship diagram of r value, yield stress, and tensile strength of the high tensile strength cold-rolled steel plate manufactured conventionally.
Claims (3)
０．００８％、ｓｏｌ．Ａｌ：０．０８％以下、Ｓ：０
．０１０％以下、Ｔｉ：０．００５〜０．０４％、Ｎｂ
：０．００３〜０．０３％、Ｍｎ０．９０％超、３．０
％以下、 Ｐ：０．０５〜０．１５％、および 残部Ｆｅおよび不可避的不純物 よりなる組成を有する鋼を熱間圧延し、次いで冷間圧延
そして５００℃から７００℃までの平均加熱速度を１０
〜１００℃／Ｓとして再結晶焼鈍をすることを特徴とす
る成形性の良好な高張力冷延鋼板の製造法。(1) In weight%, C: 0.0005 to 0.012%, N: 0.0005 to
0.008%, sol. Al: 0.08% or less, S: 0
．． 010% or less, Ti: 0.005-0.04%, Nb
:0.003~0.03%, Mn over 0.90%, 3.0
% or less, P: 0.05 to 0.15%, and the balance consisting of Fe and unavoidable impurities is hot rolled, then cold rolled, and the average heating rate from 500°C to 700°C is 10%.
A method for producing a high-strength cold-rolled steel sheet with good formability, characterized by recrystallization annealing at ~100° C./S.
０．００８％、ｓｏｌ．Ａｌ：０．０８％以下、Ｓ：０
．０１０％以下、Ｔｉ：０．００５〜０．０４％、Ｎｂ
：０．００３〜０．０３％、Ｍｎ：０．９０％超、３．
０％以下、 Ｐ：０．０５〜０．１５％、および Ｂ：０．０００１〜０．０００５％およびＭｏ：０．０
３〜０．２５％の１種または２種、ならびに 残部Ｆｅおよび不可避的不純物 よりなる組成を有する鋼を熱間圧延し、次いで冷間圧延
そして５００℃から７００℃までの平均加熱速度を１０
〜１００℃／Ｓとして再結晶焼鈍をすることを特徴とす
る成形性の良好な高張力冷延鋼板の製造法。(2) In weight%, C: 0.0005 to 0.012%, N: 0.0005 to
0.008%, sol. Al: 0.08% or less, S: 0
．． 010% or less, Ti: 0.005-0.04%, Nb
: 0.003 to 0.03%, Mn: more than 0.90%, 3.
0% or less, P: 0.05-0.15%, and B: 0.0001-0.0005% and Mo: 0.0
A steel having a composition consisting of 3 to 0.25% of one or two elements and the balance Fe and unavoidable impurities is hot rolled, then cold rolled and heated at an average heating rate of 10% from 500°C to 700°C.
A method for producing a high-strength cold-rolled steel sheet with good formability, characterized by recrystallization annealing at ~100° C./S.
有する請求項１または２記載の成形性の良好な高張力冷
延鋼板の製造法。(3) The method for producing a high-strength cold-rolled steel sheet with good formability according to claim 1 or 2, wherein the steel further contains Si: 0.02 to 0.60%.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP30181688A JPH02149624A (en) | 1988-11-29 | 1988-11-29 | Manufacture of high-tensile cold rolled steel sheet excellent in formability |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP30181688A JPH02149624A (en) | 1988-11-29 | 1988-11-29 | Manufacture of high-tensile cold rolled steel sheet excellent in formability |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH02149624A true JPH02149624A (en) | 1990-06-08 |
Family
ID=17901506
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP30181688A Pending JPH02149624A (en) | 1988-11-29 | 1988-11-29 | Manufacture of high-tensile cold rolled steel sheet excellent in formability |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH02149624A (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH04247827A (en) * | 1991-01-23 | 1992-09-03 | Nkk Corp | Manufacture of high strength cold rolled steel sheet excellent in press formability |
| EP0574814A2 (en) * | 1992-06-08 | 1993-12-22 | Kawasaki Steel Corporation | High-strength cold-rolled steel sheet excelling in deep drawability and method of producing the same |
| EP0691415A4 (en) * | 1991-03-15 | 1995-10-12 | Nippon Steel Corp | High-strength, cold-rolled steel sheet excellent in formability, hot-dip zinc coated high-strength cold rolled steel sheet, and method of manufacturing said sheets |
| KR100530076B1 (en) * | 2001-12-21 | 2005-11-22 | 주식회사 포스코 | Drawing High Strength Steel Sheet With Secondary Working Brittleness Resistance and Press Formability and A Method for Manufacturing thereof |
-
1988
- 1988-11-29 JP JP30181688A patent/JPH02149624A/en active Pending
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH04247827A (en) * | 1991-01-23 | 1992-09-03 | Nkk Corp | Manufacture of high strength cold rolled steel sheet excellent in press formability |
| JPH0826412B2 (en) * | 1991-01-23 | 1996-03-13 | 日本鋼管株式会社 | Method for producing high-strength cold-rolled steel sheet with excellent press formability |
| EP0691415A4 (en) * | 1991-03-15 | 1995-10-12 | Nippon Steel Corp | High-strength, cold-rolled steel sheet excellent in formability, hot-dip zinc coated high-strength cold rolled steel sheet, and method of manufacturing said sheets |
| EP0691415A1 (en) * | 1991-03-15 | 1996-01-10 | Nippon Steel Corporation | High-strength, cold-rolled steel sheet excellent in formability, hot-dip zinc coated high-strength cold rolled steel sheet, and method of manufacturing said sheets |
| EP0574814A2 (en) * | 1992-06-08 | 1993-12-22 | Kawasaki Steel Corporation | High-strength cold-rolled steel sheet excelling in deep drawability and method of producing the same |
| EP0574814A3 (en) * | 1992-06-08 | 1997-01-29 | Kawasaki Steel Co | High-strength cold-rolled steel sheet excelling in deep drawability and method of producing the same |
| KR100530076B1 (en) * | 2001-12-21 | 2005-11-22 | 주식회사 포스코 | Drawing High Strength Steel Sheet With Secondary Working Brittleness Resistance and Press Formability and A Method for Manufacturing thereof |
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