JPH04136123A - Production of cold rolled sheet for deep drawing having high baking hardenability - Google Patents
Production of cold rolled sheet for deep drawing having high baking hardenabilityInfo
- Publication number
- JPH04136123A JPH04136123A JP25718490A JP25718490A JPH04136123A JP H04136123 A JPH04136123 A JP H04136123A JP 25718490 A JP25718490 A JP 25718490A JP 25718490 A JP25718490 A JP 25718490A JP H04136123 A JPH04136123 A JP H04136123A
- Authority
- JP
- Japan
- Prior art keywords
- less
- steel
- amount
- content
- steel sheet
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 238000004519 manufacturing process Methods 0.000 title claims description 7
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 48
- 239000010959 steel Substances 0.000 claims abstract description 48
- 229910052717 sulfur Inorganic materials 0.000 claims abstract description 24
- 238000001816 cooling Methods 0.000 claims abstract description 22
- 229910052757 nitrogen Inorganic materials 0.000 claims abstract description 22
- 238000000137 annealing Methods 0.000 claims abstract description 18
- 238000010438 heat treatment Methods 0.000 claims abstract description 14
- 229910052796 boron Inorganic materials 0.000 claims abstract description 9
- 238000001953 recrystallisation Methods 0.000 claims abstract description 9
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims abstract description 6
- 239000000463 material Substances 0.000 claims abstract description 6
- 239000012535 impurity Substances 0.000 claims abstract description 3
- 229910052742 iron Inorganic materials 0.000 claims abstract description 3
- 229910052799 carbon Inorganic materials 0.000 abstract description 7
- 239000010960 cold rolled steel Substances 0.000 abstract description 5
- 238000005097 cold rolling Methods 0.000 abstract description 4
- 229910001209 Low-carbon steel Inorganic materials 0.000 abstract description 2
- 238000005098 hot rolling Methods 0.000 abstract description 2
- 230000001105 regulatory effect Effects 0.000 abstract description 2
- 238000002474 experimental method Methods 0.000 description 11
- 238000005096 rolling process Methods 0.000 description 8
- 230000000052 comparative effect Effects 0.000 description 7
- 229910001335 Galvanized steel Inorganic materials 0.000 description 6
- 239000008397 galvanized steel Substances 0.000 description 6
- 238000000034 method Methods 0.000 description 6
- 239000000203 mixture Substances 0.000 description 5
- 239000006104 solid solution Substances 0.000 description 5
- 230000002542 deteriorative effect Effects 0.000 description 4
- 230000007423 decrease Effects 0.000 description 3
- 230000006866 deterioration Effects 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 238000005246 galvanizing Methods 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- 238000005275 alloying Methods 0.000 description 2
- 229910052698 phosphorus Inorganic materials 0.000 description 2
- 238000007747 plating Methods 0.000 description 2
- 239000002244 precipitate Substances 0.000 description 2
- 238000001556 precipitation Methods 0.000 description 2
- 238000010791 quenching Methods 0.000 description 2
- 230000000171 quenching effect Effects 0.000 description 2
- 238000004381 surface treatment Methods 0.000 description 2
- 238000012935 Averaging Methods 0.000 description 1
- 229910000975 Carbon steel Inorganic materials 0.000 description 1
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 description 1
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 1
- 230000033228 biological regulation Effects 0.000 description 1
- 239000010962 carbon steel Substances 0.000 description 1
- 239000003575 carbonaceous material Substances 0.000 description 1
- 238000005266 casting Methods 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 230000008094 contradictory effect Effects 0.000 description 1
- 230000001276 controlling effect Effects 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 238000007872 degassing Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 239000004615 ingredient Substances 0.000 description 1
- 238000011835 investigation Methods 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 150000001247 metal acetylides Chemical class 0.000 description 1
- 150000004767 nitrides Chemical class 0.000 description 1
- 239000003973 paint Substances 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 238000002791 soaking Methods 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
- 239000011701 zinc Substances 0.000 description 1
- 229910052725 zinc Inorganic materials 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)
高延性(El)て超深絞り性(T値)を有し、プレス成
形性にすぐれ、しかも、高い焼付硬化能を有することが
、冷間圧延鋼板をはじめ表面処理鋼板の、溶融亜鉛めっ
き及び合金化溶融亜鉛めっき鋼板において必要とされる
。Detailed Description of the Invention (Industrial Application Field) It is important to have high ductility (El), ultra-deep drawability (T value), excellent press formability, and high bake hardenability. It is required for hot-dip galvanized and alloyed hot-dip galvanized steel sheets, including surface-treated steel sheets, including inter-rolled steel sheets.
ところで、近年、自動車の軽量化は燃費向上による地球
的規模での環境問題改善に有用で、そのための方策とし
て、自動車用鋼板の高強度化の要求か高まりつつある。Incidentally, in recent years, reducing the weight of automobiles is useful for improving environmental problems on a global scale by improving fuel efficiency, and as a measure for this purpose, there has been an increasing demand for higher strength steel sheets for automobiles.
一方で、プレス成形性の面から低降伏応力、高延性、優
れた深絞り性なとの特性をそなえるものでなければなら
ない。On the other hand, in terms of press formability, it must have the following characteristics: low yield stress, high ductility, and excellent deep drawability.
このような、二律背反の要求を満たすものとして、プレ
ス成形時には軟質で、その後の塗装焼付後には降伏強度
、さらには引張強度が上昇する特性、すなわち、焼付硬
化能(以下この明細書ではBH性で論じる。)の高い深
絞り用鋼板の開発か強く望まれている。In order to satisfy these contradictory requirements, we have developed a property that is soft during press forming and increases yield strength and tensile strength after the subsequent paint baking. There is a strong desire to develop steel sheets for deep drawing with high efficiencies.
(従来の技術)
BH性を有する冷延鋼板の製造方法に関して、特開昭5
3−114717号公報ではTi添加鋼について、特開
昭57−70258号公報ではNb添加鋼について、さ
らに、特開昭59−31827号公報ではTiとNbの
複合添加鋼についてそれぞれ開示されている。(Prior art) Regarding the manufacturing method of cold-rolled steel sheets having BH properties, Japanese Patent Laid-Open No. 5
No. 3-114717 discloses Ti-added steel, JP-A-57-70258 discloses Nb-added steel, and JP-A-59-31827 discloses composite addition steel of Ti and Nb.
これらは、いずれもTi及び/又はNbの添加量を制御
することや焼なまし時の冷却速度を制御することにより
、材質の劣化を生じさせることなくBH性を付与させる
ものである。In all of these, BH properties can be imparted without deteriorating the material by controlling the amount of Ti and/or Nb added and the cooling rate during annealing.
しかし、このようにTi、 Nbの添加量を制御して固
溶Cを残存させようとすると、その添加量の微妙な変化
により鋼板の性質、とりわけ延性や絞り性か大きく変化
して品質的に不安定となり、また、TiQNbを過剰に
添加するとBH性か低下するなとの問題かある。However, if we try to control the amount of Ti and Nb added in this way to ensure that solid solution C remains, subtle changes in the amount added will greatly change the properties of the steel sheet, especially the ductility and drawability, resulting in poor quality. It becomes unstable, and there is also the problem that BH properties deteriorate if TiQNb is added in excess.
このような問題点を回避するため、Tiと結合するSや
Nの含有量に制限を加える技術か、特開昭61−267
57号公報に提案開示されている。In order to avoid such problems, there is a technique that limits the content of S and N that combine with Ti, or JP-A No. 61-267.
The proposal is disclosed in Publication No. 57.
しかしながら、この技術によると、T値、Elを向上さ
せるための同効成分としてB、Nbを添加しているもの
の、製造条件についての特別の考慮か払われていないた
め、超深絞り性と共に3kgf/mm2から5kgf/
mm2の焼付硬化量(単にBt(量という)か得られて
はいるものの、5kgf/mm2を越える高いBH量を
深絞り性の劣化なしに安定して確保するまでには至って
いない。However, according to this technology, although B and Nb are added as the same effective ingredients to improve the T value and El, no special consideration is given to the manufacturing conditions, so the ultra-deep drawability and 3kgf /mm2 to 5kgf/
Although a bake hardening amount (simply referred to as Bt) of mm2 has been obtained, it has not yet been possible to stably secure a high BH amount exceeding 5 kgf/mm2 without deteriorating deep drawability.
(発明か解決しようとする課題)
この発明は、T1を添加した極低炭素鋼をベースにして
、成分組成と焼鈍条件を適正化することにより、高いB
H性を有する深絞り用冷延板を製造することにある。(Problem to be solved by the invention) This invention is based on ultra-low carbon steel with T1 added, and by optimizing the component composition and annealing conditions, a high B
The purpose of the present invention is to produce a cold-rolled sheet for deep drawing having H properties.
ここに、冷延板というのは、冷間圧延鋼板のみならず、
液体亜鉛中に浸漬しめつき処理を施した溶融亜鉛めっき
鋼板及び合金化溶融亜鉛めっき鋼板用原板を包含するも
のである。Here, cold-rolled sheets include not only cold-rolled steel sheets, but also cold-rolled sheets.
This includes hot-dip galvanized steel sheets and base sheets for alloyed hot-dip galvanized steel sheets that have been immersed in liquid zinc and subjected to plating treatment.
(課題を解決するための手段)
この発明は、種々実験の結果、T1添加の極イ氏炭素鋼
において、S、Hの含有量の規則、Bの添カロに加えて
、焼鈍条件を特定することにより、Jト常に高いBH性
か得られることを見出したもので、その要旨は
C: 0.0005 wt%以上、0.0060 wt
%以下、Si : 1.5 wt%以下、
Mn : 1.5 wt%以下、
Ti : 0.005 wt%以上、0.10wt%以
下、B : 0.0004 wt%以上、0.0015
wt%以下、Al : 0.005 wt%以上、0
.100 wt%以下、P:0.15wt%以下、
S : 0.0030 wt%以下、及びN・0.00
40 wt%以下、
を含み、
SとNの含有量の合計か0.0050 wt%以下にお
いて、
次式
て与えられる有効Ti(Ti”)か(Cwt%〕の4倍
から20倍の範囲となる条件を満たし、残部は鉄および
不可避不純物組成からなる鋼素材に、熱間圧延を施し、
ついて、冷間圧延を行った後、この鋼板をl″C/SC
/3以上度で、730°C以上900°C以下の温度範
囲に昇温させ、その後、550°C以下の温度まで20
°C/S以上の冷却速度で急冷する条件で再結晶焼鈍を
行なうことを特徴とする高い焼付硬化能を有する深絞り
用冷延板の製造方法である。(Means for Solving the Problems) As a result of various experiments, the present invention specifies the annealing conditions in addition to the rules for the content of S and H and the addition of B in carbon steel with T1 addition. It was discovered that by doing so, a consistently high BH property can be obtained.
% or less, Si: 1.5 wt% or less, Mn: 1.5 wt% or less, Ti: 0.005 wt% or more, 0.10 wt% or less, B: 0.0004 wt% or more, 0.0015
wt% or less, Al: 0.005 wt% or more, 0
.. 100 wt% or less, P: 0.15 wt% or less, S: 0.0030 wt% or less, and N・0.00
40 wt% or less, including 0.0050 wt% or less of the total content of S and N, and a range of 4 to 20 times the effective Ti (Ti") (Cwt%) given by the following formula: A steel material that satisfies the following conditions and the remainder consists of iron and unavoidable impurities is subjected to hot rolling,
Then, after performing cold rolling, this steel plate was subjected to l″C/SC
/3 degrees or more, raise the temperature to a temperature range of 730°C or more and 900°C or less, and then raise the temperature to a temperature of 550°C or less for 20 minutes.
This is a method for producing a cold-rolled sheet for deep drawing having high bake hardenability, characterized in that recrystallization annealing is performed under conditions of rapid cooling at a cooling rate of .degree. C./S or more.
ここに、再結晶焼鈍においては、730°C以上900
°C以下の温度範囲に昇温させた後、該温度に30秒程
度の短時間の均熱保持を施す場合を含むものである。Here, in recrystallization annealing, the temperature is 730°C or higher and 900°C.
This includes a case in which, after raising the temperature to a temperature range of .degree. C. or lower, the temperature is soaked for a short period of about 30 seconds.
(作 用)
まず、この発明に至った実験について、その内容を説明
する。(Function) First, the contents of the experiment that led to this invention will be explained.
(実験1)
C: 0.0021wt%、Si : 0.01wt%
、Mn : 0.12wt%、Al : 0.046
wt%、P二0.011 wt%を含み、B、 S。(Experiment 1) C: 0.0021wt%, Si: 0.01wt%
, Mn: 0.12wt%, Al: 0.046
wt%, P2 containing 0.011 wt%, B, S.
Nの含有量を変化させ、T1については有効Ti (w
t%)かC(wt%)の7倍から8倍になるように調整
した真空溶解鋼を実験室的に作成し、板厚3.5mmま
で熱間圧延後、0.7mmまて冷間圧延した。この圧延
薄板を5°C/Sの加熱速度で795°Cに加熱して1
5秒間均熱保持し、ついて、室温まで35℃/Sて急冷
する連続焼鈍タイプの熱サイクルを施し、0゜7%伸び
の調質圧延を行なった。By changing the N content, effective Ti (w
Vacuum melted steel adjusted to 7 to 8 times C (wt%) or C (wt%) was prepared in the laboratory, hot rolled to a thickness of 3.5 mm, and then cold rolled to a thickness of 0.7 mm. Rolled. This rolled thin plate was heated to 795°C at a heating rate of 5°C/S.
A continuous annealing type thermal cycle was performed in which the material was soaked for 5 seconds, then rapidly cooled to room temperature at 35° C./S, and then temper rolled with an elongation of 0° and 7%.
このようにして得られた冷延板について、伸び(EN)
、BH量を調査した。Regarding the cold-rolled sheet obtained in this way, the elongation (EN)
, the amount of BH was investigated.
第1図にS、 N、及びS含有量と、EA、 Bl(量
の関係を示す。Figure 1 shows the relationship between the S, N, and S contents and the amounts of EA and Bl.
ここに、Elは圧延方向に対し平行(Ezo)、45°
方向(EJ?ns)、及び90°方向(Ef9゜)に採
取した試験片の測定結果を次式で平均化して求めた値で
あり、
BH量は、第2図に示すように、2%の引張歪みを施し
た後、170°Cて20分間の焼付は相当の熱処理を行
い、この時の降伏点の上昇量を測定した値である。Here, El is parallel to the rolling direction (Ezo), 45°
This is a value obtained by averaging the measurement results of test pieces taken in the direction (EJ?ns) and the 90° direction (Ef9°) using the following formula, and the amount of BH is 2% as shown in Figure 2. After applying tensile strain, a considerable heat treatment was performed at 170°C for 20 minutes, and the increase in yield point at this time was measured.
第1図より、SとNの含有量の和か減少するとともにE
l、BH量は増加する傾向を示し、B添加の影響はBH
量に顕著に現われている。すなわち、SとNの含有量の
和か50wtppm(0,005wt%)で比較すると
、B無添加鋼か3kgf/mm2のBH量量であるのに
対し、S含有量かl1wt PPmになると5kgf/
mm2と高いBH量を示すか、S含有量かさらに増加し
て20wtp1)mになるとBH量は3kgf/mm2
と低下する。From Figure 1, as the sum of S and N contents decreases, E
l, the amount of BH shows an increasing tendency, and the effect of B addition is
It is noticeable in quantity. In other words, when comparing the sum of the S and N contents, which is 50wtppm (0,005wt%), BH content is 3kgf/mm2 for B-free steel, whereas it is 5kgf/mm2 for S content of l1wt PPm.
If the BH content is as high as mm2, or the S content further increases to 20wtp1)m, the BH amount is 3kgf/mm2.
and decreases.
そして、S含有量かllwtl)pmでSとNの含有量
の和か20wtppm以下の鋼では、”kgf/mm2
以上と非常に高いBH量を示している。For steels with S content (llwtl)pm and the sum of S and N contents less than 20wtppm, "kgf/mm2
This shows a very high amount of BH.
一方、S含有量かIlwtppmであっても、S含有量
か40wtppmの鋼や、N含有量か45wtppmの
鋼では、SとNの合計の含有量か50wt pf)mで
あるにもかかわらす4kgf/mm”未満のBH量しか
得られていない。On the other hand, even if the S content is Ilwtppm, in steel with an S content of 40wtppm or steel with an N content of 45wtppm, the total S and N content is 4kgf even though the total content is 50wt pf)m. The amount of BH less than "/mm" was obtained.
(実験2)
実験1と同じ含有量のC,Si、Mn、A1. Pを
有し、かつ、有効Ti (wt%)かC(wt%)の8
倍から10倍て、S : 0.0015wt%から0.
002wt%、N : 0.0018wt%から0.0
022wt%を含有する成分系にBを0.0029wt
%まての間で添加した鋼(B無添加鋼も含む)を実験1
と同じ処理を行なって鋼板を製造し、これらの鋼板につ
いてBH量を測定した。B添加量とBH量の関係を第3
図に示す。第3図から明らかなように、B添加量か4
wtppmから15wtl)pmの間て、BH量は5k
gf/mm2以上になっている。(Experiment 2) The same contents of C, Si, Mn, and A1 as in Experiment 1 were used. P and effective Ti (wt%) or C (wt%) of 8
From 10 times to 10 times, S: 0.0015wt% to 0.
002wt%, N: 0.0018wt% to 0.0
0.0029wt of B in the component system containing 022wt%
In Experiment 1, steels (including B-free steels) added between
Steel plates were manufactured using the same process as above, and the BH content of these steel plates was measured. The relationship between the amount of B added and the amount of BH is shown in the third
As shown in the figure. As is clear from Figure 3, the amount of B added is 4
Between wtppm and 15wtl)pm, the amount of BH is 5k
gf/mm2 or more.
実験1および実験2の結果より、S、 N、 Bの含
有量及びSとNの含有量の和はBH量に大きく影響する
ことから、これらの含有量を規制すること、さらには連
続焼鈍での冷却速度を適正化することにより、
て表わされるTビかC(wt%)の4倍以上であっても
、すなわちCに対する有効なT1の原子比が1.0以上
であっても、5kgf/a+m2以上の高いBH量が得
られることか明らかとなった。From the results of Experiments 1 and 2, the contents of S, N, and B, as well as the sum of the contents of S and N, greatly affect the amount of BH. By optimizing the cooling rate of It became clear that a high BH amount of /a+m2 or more could be obtained.
これらの結果について、まずSとNの含有量を規制する
ことによりBH性が向上する理由は、TiS、ならびに
TiNの析出物の減少により、TiCの析出核か減少し
、形成されたTiCが不安定になり固溶Cか残留しやす
いことによるものと考えられ、また、4 wtppmか
ら15Wtppmの範囲のB添加により、BH性か向上
する理由は明らかではないが、Bが粒界に偏析しやすい
元素であるため、固溶Cを安定化する傾向か高いことに
よるものと考えられ、さらにB添加量か15wtppm
を超えると再びBH性が低下する現象は、Bの一部が窒
化物を形成し、有効なTi量を増加させることによるも
のと推定する。Regarding these results, the reason why the BH properties are improved by regulating the content of S and N is that due to the reduction of TiS and TiN precipitates, the number of TiC precipitate nuclei is reduced, and the formed TiC is This is thought to be due to the fact that it becomes stable and solid solution C tends to remain.Also, it is not clear why BH properties are improved by adding B in the range of 4 wtppm to 15 Wtppm, but B tends to segregate at grain boundaries. This is thought to be due to the fact that it has a high tendency to stabilize solid solution C because it is an element, and the amount of B added is 15wtppm.
It is presumed that the phenomenon in which the BH property deteriorates again when the temperature exceeds 100% is due to part of B forming nitrides and increasing the effective amount of Ti.
つぎに、この発明の鋼組成における化学成分範囲の限定
理由を以下に述べる。Next, the reason for limiting the range of chemical components in the steel composition of this invention will be described below.
C:良好な深絞り性や延性を得るためには少ないほど有
利である。0.0060 wt%を超えると後述のTi
量を増しても良好な延性や深絞り性が得られなくなる。C: In order to obtain good deep drawability and ductility, the smaller the amount, the more advantageous. If it exceeds 0.0060 wt%, Ti
Even if the amount is increased, good ductility and deep drawability cannot be obtained.
一方、0.0005wt%未満では、この発明の目的で
ある高いBH性か得られない。On the other hand, if it is less than 0.0005 wt%, the high BH properties that are the object of this invention cannot be obtained.
したがって、その含有量は000005wt%以上0.
0060wt%以下とする。Therefore, its content is 0.000005 wt% or more.
0060wt% or less.
Si、Mn :深絞り性をあまり劣化させずに鋼板の強
度を上昇させるために有効な元素である。しかし、多量
の添加は、加工性はかりてなく溶接性や表面処理性も劣
化させるので、それらの含有量は、上限をそれぞれ、S
lを1.5wt%、Mnを1.5wt%とする。Si, Mn: These are elements effective for increasing the strength of the steel sheet without significantly deteriorating the deep drawability. However, if large amounts are added, the processability is immeasurable and the weldability and surface treatment properties are also deteriorated, so the upper limit of their content should be set to S
Let l be 1.5 wt% and Mn be 1.5 wt%.
T1.含有量か少ないと7値、伸びなどの改善効果か期
待できず、また、多過ぎると、鋼の鋳造段階でのノズル
詰まり、表面性状の劣化、コストアップなとの問題を生
ずる。T1. If the content is too low, it cannot be expected to improve the 7 value, elongation, etc., and if it is too high, problems such as nozzle clogging during the steel casting stage, deterioration of surface properties, and increased costs will occur.
したかって、その含有量は0.005 wt%以上0.
10wt%以下とし、
さらに、TiはS、 N、そしてCを固定するために添
加するものであることから、これらの含有量との関係に
おいて、
て表わされる有効Ti量をC(wt%)の4倍以上20
倍以下の範囲となる条件を満たすことを必要とする。Therefore, its content is 0.005 wt% or more.
10wt% or less, and since Ti is added to fix S, N, and C, in relation to these contents, the effective Ti amount expressed as: C (wt%) 4 times or more 20
It is necessary to satisfy the condition that the range is less than or equal to
なお、従来、深絞り用鋼板を製造するため、S。In addition, conventionally, in order to manufacture steel sheets for deep drawing, S.
N、及びCを完全に固定する目的で、有効TiかC(w
t%)の4倍以上、すなわち原子比で1以上になるよう
に調整して添加されていたが、この場合には、固溶Cか
存在しないので、深絞り性はともかく、優れたBH性を
得ることはできなかった。しかし、この発明においては
、有効TiかC(wt%)の4倍以上であっても、深絞
り性とともに優れたBl(性を有する鋼板か得られるよ
うにしたものである。In order to completely fix N and C, the effective Ti or C(w
t%), that is, the atomic ratio is 1 or more, but in this case, since there is no solid solution C, it has excellent BH properties, apart from deep drawability. I couldn't get it. However, in this invention, even if the effective Ti or C (wt%) is four times or more, a steel sheet can be obtained that has excellent Bl (Bl) properties as well as deep drawability.
B:この発明において最も重要な成分てあり、前記した
実験l及び実験2の結果より明らかなように、5kgf
/mm2を超える高いB)I量を得るためには、
その含有量は、0.0004wt%以上0.0015w
t%以下とする必要かある。B: This is the most important component in this invention, and as is clear from the results of Experiment 1 and Experiment 2 described above, 5 kgf
In order to obtain a high amount of B)I exceeding /mm2, the content should be 0.0004wt% or more and 0.0015w
Is it necessary to keep it below t%?
A1:鋼の脱酸に必要であるか、過剰な添加は効果か飽
和するばかりでなく、表面性状を劣化させる。A1: Is it necessary for deoxidizing steel? Excessive addition not only saturates the effect but also deteriorates the surface quality.
したかって、その含有量は、0.005 wt%以上0
゜100 wt%以下とする。Therefore, its content is 0.005 wt% or more.
゜100 wt% or less.
P:Si、Mnと同様深絞り性をあまり劣化させずに鋼
板の強度を上昇させるために有効な元素であるか、過剰
添加は加工性、溶接性、表面処理性を劣化させる。P: Like Si and Mn, it is an effective element for increasing the strength of steel sheets without significantly deteriorating deep drawability, but excessive addition deteriorates workability, weldability, and surface treatment.
したかって、その含有量は、0.15wt%以下とする
。Therefore, its content should be 0.15 wt% or less.
S、N・これらの成分規制は、この発明にとって重要で
ある。前記した実験1及び実験2の結果−より、5kg
f/mm2を超える高いBl量を得るためには、それら
の含有量は、上限をそれぞれ、Sを0、0030wt%
、Nを0.0040wt%とし、さらにSとNの含有量
の和を0.0050wt%とする必要かある。S, N: Regulation of these components is important for this invention. From the results of Experiment 1 and Experiment 2 described above, 5 kg
In order to obtain a high Bl content exceeding f/mm2, their content should be set to an upper limit of 0,0030 wt% for S, respectively.
, N should be 0.0040 wt%, and the sum of the S and N contents should be 0.0050 wt%.
つぎに製造方法について述へる。Next, the manufacturing method will be described.
上記の組成を有する鋼を溶製後、常法によりスラブとし
、熱間圧延をし、ついで冷間圧延を行なった後、1’C
/S以上の加熱速度で加熱し、その後急速冷却すること
により、再結晶焼鈍を行う。After melting the steel having the above composition, it is made into a slab by a conventional method, hot rolled, then cold rolled, and then 1'C
Recrystallization annealing is performed by heating at a heating rate of /S or higher and then rapid cooling.
再結晶焼鈍における加熱速度は、加熱中におけるTiC
の分解を防止するため1℃/S以上であることか必要で
あり、加熱温度は完全再結晶組織を得るために最低73
0℃を必要とする。しかし、加熱温度の上昇とともにr
値や伸びは向上するか、900°Cを超えると変態によ
るr値の劣化かおこるとともに、結晶粒粗大化によりプ
レス成形性か著しく低下する。したかって、その上限は
900°Cとする。The heating rate in recrystallization annealing is
The heating temperature must be at least 1°C/S to prevent the decomposition of
Requires 0°C. However, as the heating temperature increases, r
The value and elongation may improve, but if the temperature exceeds 900°C, the r value may deteriorate due to transformation, and the press formability may significantly decrease due to coarsening of crystal grains. Therefore, the upper limit is set at 900°C.
730°Cから900°Cの温度範囲に加熱後、短時間
の均熱保持を含み急冷する。この時の冷却速度か遅いと
冷却中にTiCの析出か進行し、5kgf/m+n2以
上の高いB)(量を確保することかできなくなる。After heating to a temperature range of 730°C to 900°C, it is rapidly cooled, including a short soaking period. If the cooling rate at this time is slow, precipitation of TiC will proceed during cooling, making it impossible to secure a high B) amount of 5 kgf/m+n2 or more.
したかって冷却速度を20°C/S以上に限定する。Therefore, the cooling rate is limited to 20°C/S or more.
また、Ti系の炭化物の析出速度は550°C以下ては
無視てきるほど遅いので、急冷終了温度は最高550°
Cとし、それ以降の冷却パターンについては特に制限す
る必要はなく、さらに、再結晶焼鈍後に450″Cから
550″Cてめっき及び必要に応じて合金化熱処理を施
す溶融亜鉛めっきプロセスにも適用できる。In addition, the precipitation rate of Ti-based carbides is negligibly slow below 550°C, so the maximum temperature at which quenching ends is 550°C.
C, and there is no need to particularly limit the cooling pattern thereafter, and it can also be applied to a hot-dip galvanizing process in which plating is performed at 450"C to 550"C after recrystallization annealing, and alloying heat treatment is performed as necessary. .
なお、この発明方法によって得られる冷延鋼板、及び溶
融亜鉛めっき鋼板は、固溶Cか存在すること、Bを添加
していることなとから、優れた耐2次加工脆性をも有し
ている。Furthermore, the cold-rolled steel sheets and hot-dip galvanized steel sheets obtained by the method of this invention also have excellent resistance to secondary work brittleness due to the presence of solid solution C and the addition of B. There is.
(実施例)
実施例1
この発明の適合鋼10種類、比較鋼7種類の鋼を転炉お
よびRH脱ガスプロセスにて溶製し、連鋳スラブとした
。このスラブを1200°Cに加熱後、仕上げ圧延温度
910’C,巻取り温度590°Cで熱延コイルとし、
デスケーリング後、圧下率78%て冷間圧延し、板厚0
.7mの冷延板とした。ついで、連続焼鈍炉にて5°C
/Sの加熱速度で820°Cに加熱し、20秒間保持後
400°Cまで35°C/Sの冷却速度で冷却し、40
0°C以下は5°C/Sの冷却速度で徐冷した後、0.
6%の調質圧延を行なった。(Examples) Example 1 Ten types of compatible steel of the present invention and seven types of comparative steel were melted in a converter and an RH degassing process to form continuous cast slabs. After heating this slab to 1200°C, it is made into a hot rolled coil at a finish rolling temperature of 910'C and a coiling temperature of 590°C.
After descaling, cold rolling was performed at a reduction rate of 78%, and the plate thickness was 0.
.. It was made into a 7 m cold rolled plate. Then, it was heated to 5°C in a continuous annealing furnace.
Heated to 820 °C at a heating rate of /S, held for 20 seconds, cooled to 400 °C at a cooling rate of 35 °C/S,
Below 0°C, after cooling slowly at a cooling rate of 5°C/S,
6% temper rolling was performed.
これらの鋼の化学成分組成を表1に、調質圧延後の冷延
板の引張特性を表2に示す。The chemical compositions of these steels are shown in Table 1, and the tensile properties of the cold rolled sheets after temper rolling are shown in Table 2.
表2
表2に示すYS、TS、 El、 r値は、それぞれ
板面内において、圧延方向(Z、)、圧延方向に対して
45゛方向(z4.)、及び圧延方向に対し90’方向
(z、e)の測定値を用いて次式で計算した平均値であ
る。Table 2 The YS, TS, El, and r values shown in Table 2 are in the rolling direction (Z,), 45° direction (z4.) with respect to the rolling direction, and 90′ direction with respect to the rolling direction, respectively, within the plate surface. This is an average value calculated using the following formula using the measured values of (z, e).
表2により、この発明の適合側鋼biから7は、5kg
f/mm2以上の高いBl(量と、51以上の伸びとと
もにr値か1,9以上と良好な深絞り性を示しており、
Si、Mn、Pなとの含有量を多くし高張力化した、こ
の発明の適合側鋼Nα8. 9.10においても、引張
強さが高いにもかかわらず5kgf/ai2以上の高い
BHiとともにr値2.1以上と良好な深絞り性を示し
ている。According to Table 2, the compatible side steels bi to 7 of this invention are 5 kg
It shows high Bl (amount of f/mm2 or more), elongation of 51 or more, and good deep drawability with an r value of 1.9 or more.
The compatible side steel Nα8. of the present invention has a high tensile strength by increasing the content of Si, Mn, and P. 9.10 also shows good deep drawability with a high BHi of 5 kgf/ai2 or more and an r value of 2.1 or more despite the high tensile strength.
一方、B量の多い比較例鋼N(Lll、 N量の多い比
較例鋼Nα12、S+N量の多い比較例鋼Nα13、B
量か上下限を外れた比較例鋼N[lI4.15.、及び
有効Tiか(Cwt% )の20倍以上の比較例鋼N(
lI6ては、Bl(量か5kgf/rnm2以下と劣っ
ている。On the other hand, comparative example steel N (Lll) with a large amount of B, comparative example steel Nα12 with a large amount of N, comparative example steel Nα13 with a large amount of S+N, B
Comparative example steel N [lI4.15. , and comparative example steel N (with a content of more than 20 times the effective Ti (Cwt%))
II6 is inferior, with Bl (amount) being less than 5 kgf/rnm2.
また、C量の多い比較例鋼N(l17は、伸び、下値か
劣化している。In addition, Comparative Example Steel N (117) with a large amount of C has elongated and deteriorated.
なお、これら、この発明の適合例の鋼板は、3か月装置
しても降伏点伸びの発生、及び伸び特性の劣化は見られ
なかった。In addition, in these steel plates according to the present invention, no elongation at yield point occurred and no deterioration in elongation properties was observed even after 3 months of use in the apparatus.
実施例2
表1に示す、鋼Nαlの化学成分組成を有する鋼スラブ
を用いて、冷延工程までは実施例1と同じ工程処理条件
で板厚0.7mmの冷延板とし、連続焼鈍炉にて7°C
/Sの加熱速度で820°Cに加熱し、30秒間保持の
焼鈍後、種々の冷却パターンで処理し、一部溶融亜鉛め
っき処理も合せ行った。これらの鋼板について0,6%
の調質圧延を行ない実施例1と同様の方法て引張特性を
調査した。Example 2 A steel slab having the chemical composition of steel Nαl shown in Table 1 was used to form a cold rolled plate with a thickness of 0.7 mm under the same process conditions as in Example 1 up to the cold rolling process, and then heated in a continuous annealing furnace. at 7°C
After annealing at a heating rate of /S to 820°C and holding for 30 seconds, various cooling patterns were used, and some of the samples were also hot-dip galvanized. 0,6% for these steel plates
Temper rolling was carried out, and the tensile properties were investigated in the same manner as in Example 1.
焼鈍後の冷却パターン及び溶融亜鉛めっき条件を表3に
、引張特性の調査結果を表4に示す。Table 3 shows the cooling pattern after annealing and hot-dip galvanizing conditions, and Table 4 shows the results of the investigation of tensile properties.
表4より冷却速度が20°C/Sより遅い試料Nα3、
及び急冷終了温度か550°Cより高い試料隘5の場合
にはBH量5kgf/mm2を得ることはてきないか、
この発明の処理条件では安定してBH量5kgf/11
m2以上を確保することができることを示している。From Table 4, sample Nα3 whose cooling rate is slower than 20°C/S,
And in the case of sample size 5 where the quenching end temperature is higher than 550°C, is it possible to obtain a BH amount of 5 kgf/mm2?
Under the processing conditions of this invention, the BH amount is stably 5 kgf/11.
This shows that it is possible to secure m2 or more.
また、合金化溶融亜鉛めっき処理を施した試料Nα6に
おいても、伸び、7値などの材質の劣化をともなうこと
なくBH量5kgf/mm”以上の値か得られている。Further, even in sample Nα6 subjected to alloying hot-dip galvanizing treatment, a BH amount of 5 kgf/mm” or more was obtained without deterioration of the material properties such as elongation and 7 value.
(発明の効果)
この発明は、S、 N、の含有量を規制し、さらにBを
添加しその含有量を規制し、有効TiをCとの原子比で
1.0以上含有する極低炭素鋼を用い、再結晶焼鈍にお
ける冷却パターンを適正化することにより、高い焼付硬
化性が、良好な深絞り性と共に得られることを見出した
もので、この発明のよって得られる冷延板は、深絞り用
冷延鋼板として、また、溶融亜鉛めっき鋼板用及び合金
化溶融亜鉛めっき鋼板用として好適である。(Effect of the invention) This invention regulates the content of S, N, and further controls the content by adding B, and produces an extremely low carbon material containing effective Ti and C in an atomic ratio of 1.0 or more. It has been discovered that by using steel and optimizing the cooling pattern during recrystallization annealing, high bake hardenability can be obtained along with good deep drawability. It is suitable as a cold-rolled steel sheet for drawing, and also as a hot-dip galvanized steel sheet and an alloyed hot-dip galvanized steel sheet.
第1図は、BH量におよほす、S、N及びB含有量の影
響を示すグラフ、
第2図は、BH量の測定要領を示すグラフ、及び、第3
図は、BH量におよばず焼鈍後の冷却速度の影響を示す
グラフである。Figure 1 is a graph showing the influence of S, N, and B contents on BH content; Figure 2 is a graph showing how to measure BH content;
The figure is a graph showing the influence of the cooling rate after annealing, regardless of the amount of BH.
Claims (1)
以下、Si:1.5wt%以下、Mn:1.5wt%以
下、 Ti:0.005wt%以上、0.10wt%以下、B
:0.0004wt%以上、0.0015wt%以下、
Al:0.005wt%以上、0.100wt%以下、
P:0.15wt%以下、 S:0.0030wt%以下、及び N:0.0040wt%以下、 を含み、 SとNの含有量の合計が0.0050wt%以下におい
て、 次式 Ti^≠wt%=([Tiwt%]−48/14[Nw
t%]−48/32[Swt%])で与えられる有効T
i(Ti^≠)が〔Cwt%〕の4倍から20倍の範囲
となる条件を満たし、残部は鉄および不可避不純物組成
からなる鋼素材に、 熱間圧延を施し、ついで、冷間圧延を行った後、この鋼
板を1℃/S以上の加熱速度で、730℃以上900℃
以下の温度範囲に昇温させ、その後、550℃以下の温
度まで20℃/S以上の冷却速度で急冷する条件で再結
晶焼鈍を行なうことを特徴とする高い焼付硬化能を有す
る深絞り用冷延板の製造方法。[Claims] 1. C: 0.0005wt% or more, 0.0060wt%
Below, Si: 1.5 wt% or less, Mn: 1.5 wt% or less, Ti: 0.005 wt% or more, 0.10 wt% or less, B
: 0.0004wt% or more, 0.0015wt% or less,
Al: 0.005wt% or more, 0.100wt% or less,
P: 0.15wt% or less, S: 0.0030wt% or less, and N: 0.0040wt% or less, and when the total content of S and N is 0.0050wt% or less, the following formula Ti^≠wt %=([Tiwt%]-48/14[Nw
t%]-48/32[Swt%])
A steel material that satisfies the condition that i (Ti^≠) is in the range of 4 to 20 times [Cwt%], and the remainder consists of iron and unavoidable impurities, is hot rolled and then cold rolled. After that, the steel plate is heated to 730°C or more and 900°C at a heating rate of 1°C/S or more.
Deep-drawing cooling with high bake hardenability characterized by recrystallization annealing under the conditions of raising the temperature to the following temperature range and then rapidly cooling to a temperature of 550°C or less at a cooling rate of 20°C/S or more. Manufacturing method of rolled plate.
Priority Applications (1)
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JP2257184A JP2793348B2 (en) | 1990-09-28 | 1990-09-28 | Manufacturing method of cold-rolled sheet for deep drawing with high bake hardenability |
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JP2257184A JP2793348B2 (en) | 1990-09-28 | 1990-09-28 | Manufacturing method of cold-rolled sheet for deep drawing with high bake hardenability |
Publications (2)
Publication Number | Publication Date |
---|---|
JPH04136123A true JPH04136123A (en) | 1992-05-11 |
JP2793348B2 JP2793348B2 (en) | 1998-09-03 |
Family
ID=17302849
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JP2257184A Expired - Fee Related JP2793348B2 (en) | 1990-09-28 | 1990-09-28 | Manufacturing method of cold-rolled sheet for deep drawing with high bake hardenability |
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Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH05195148A (en) * | 1992-01-20 | 1993-08-03 | Nippon Steel Corp | Cold-rolled steel sheet excellent in curing performance for baking paint and secondary workability, galvanized cold-rolled steel sheet and production thereof |
KR20020084607A (en) * | 2001-05-03 | 2002-11-09 | 현대자동차주식회사 | The composition and its manufacturing process of bake hardenable high strength steel sheets |
CN100396808C (en) * | 2004-05-28 | 2008-06-25 | 宝山钢铁股份有限公司 | Cold rolling glass-lined steel having excellent scale cracking resistance and extra-deep drawing property and manufacturing method thereof |
CN104593674A (en) * | 2015-01-21 | 2015-05-06 | 首钢总公司 | Hot-dip galvanized ultra-low carbon bake-hardening steel and production method thereof |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS5938337A (en) * | 1982-08-28 | 1984-03-02 | Nippon Steel Corp | Manufacture of steel plate with burning hardenability for extremely deep drawing |
JPS61276928A (en) * | 1985-05-31 | 1986-12-06 | Kawasaki Steel Corp | Production of cold rolled steel sheet for deep drawing having baking hardenability |
JPS61276962A (en) * | 1985-05-31 | 1986-12-06 | Kawasaki Steel Corp | Alloyed and galvanized steel sheet for deep drawing having excellent baking hardenability and powdering resistance |
-
1990
- 1990-09-28 JP JP2257184A patent/JP2793348B2/en not_active Expired - Fee Related
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS5938337A (en) * | 1982-08-28 | 1984-03-02 | Nippon Steel Corp | Manufacture of steel plate with burning hardenability for extremely deep drawing |
JPS61276928A (en) * | 1985-05-31 | 1986-12-06 | Kawasaki Steel Corp | Production of cold rolled steel sheet for deep drawing having baking hardenability |
JPS61276962A (en) * | 1985-05-31 | 1986-12-06 | Kawasaki Steel Corp | Alloyed and galvanized steel sheet for deep drawing having excellent baking hardenability and powdering resistance |
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH05195148A (en) * | 1992-01-20 | 1993-08-03 | Nippon Steel Corp | Cold-rolled steel sheet excellent in curing performance for baking paint and secondary workability, galvanized cold-rolled steel sheet and production thereof |
KR20020084607A (en) * | 2001-05-03 | 2002-11-09 | 현대자동차주식회사 | The composition and its manufacturing process of bake hardenable high strength steel sheets |
CN100396808C (en) * | 2004-05-28 | 2008-06-25 | 宝山钢铁股份有限公司 | Cold rolling glass-lined steel having excellent scale cracking resistance and extra-deep drawing property and manufacturing method thereof |
CN104593674A (en) * | 2015-01-21 | 2015-05-06 | 首钢总公司 | Hot-dip galvanized ultra-low carbon bake-hardening steel and production method thereof |
Also Published As
Publication number | Publication date |
---|---|
JP2793348B2 (en) | 1998-09-03 |
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