JPS58217638A - Preparation of cold rolled steel plate good in ageing resistance and ductility - Google Patents
Preparation of cold rolled steel plate good in ageing resistance and ductilityInfo
- Publication number
- JPS58217638A JPS58217638A JP10166682A JP10166682A JPS58217638A JP S58217638 A JPS58217638 A JP S58217638A JP 10166682 A JP10166682 A JP 10166682A JP 10166682 A JP10166682 A JP 10166682A JP S58217638 A JPS58217638 A JP S58217638A
- Authority
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- Japan
- Prior art keywords
- temperature
- steel plate
- overaging
- ductility
- rolled 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.)
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Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Mechanical Engineering (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Heat Treatment Of Steel (AREA)
- Heat Treatment Of Sheet Steel (AREA)
Abstract
Description
【発明の詳細な説明】
この発明は、耐時効性と延性の良好な、冷延鋼板製造法
に関し、とくにかかる性能を、連続焼鈍処理によって有
利に実現することを可能ならしめようとするものである
。[Detailed Description of the Invention] The present invention relates to a method for producing cold rolled steel sheets with good aging resistance and ductility, and particularly aims to make it possible to advantageously achieve such performance by continuous annealing treatment. be.
さて一般に冷延鋼板の冷間圧延後の焼鈍過程は、連続焼
鈍処理が、これまでの箱焼鈍にとってかわりつつある。Now, in general, in the annealing process of cold rolled steel sheets after cold rolling, continuous annealing treatment is replacing the conventional box annealing.
連続焼鈍法は、従来の箱焼鈍法で数日を要して製造され
ていた軟質な冷延鋼板が数分で製造できる画期的な方法
である。The continuous annealing method is a revolutionary method that allows the production of soft cold-rolled steel sheets in a few minutes, which previously took several days using the conventional box annealing method.
短時間で焼鈍を完了させるため連続焼鈍法では再結晶焼
鈍後に急冷却とそれに続く過時効処理を行ない、鋼中に
固溶しているOを無害な形すなわちFe50 (セメン
タイト)として析出されることにより軟質化による延性
の向上と固溶0による耐時効性の向上を図っている。In order to complete annealing in a short time, the continuous annealing method involves rapid cooling after recrystallization annealing, followed by overaging treatment, and the O dissolved in solid solution in the steel is precipitated in a harmless form, namely Fe50 (cementite). This aims to improve ductility by softening the steel and improve aging resistance by eliminating solid solution.
従来、用いられている連続焼鈍法のヒートサイクルの一
例を181図、第8図に示す。第3図は再結晶焼鈍後に
10〜b
〜400℃で数分の過時効処理を行なう例であり、また
第8図は再結晶焼鈍後、室温近くまで水冷((約200
0℃/ seo ) L、再加熱して850〜450℃
で数分の過時効処理を行なう場合である@第8図のヒー
トサイクルでは、過時効処理前の冷却が10〜80℃/
seoのように遅いため固溶0の過飽和度が小さく
Fe50の析出核が出来にくく後に続く過時効処理中に
Fe30として析出する速度は著しく緩慢である。その
結果充分に過時効時間(約5 min以上)をとれば、
固溶Oが減少し、また析出したFe30は、延性に対し
て無害な形で存在するので、耐時効性、延性とも良好な
鋼板の製造が可能ではあるが、これを実現するためには
、鋼板を連続焼鈍炉に通す際、通板スピードを遅くして
過時効処理帯の滞留時間を長くするか、過時効処理炉自
体を長大化させる必要があり、コストの上昇を伴う。こ
れに対し、第2図のサイクルで過時効時間を6分以下に
すると、過時効処理を行っても固溶0が充分に減少せず
、軟質化による延性の増加及び耐時効性の改善は期待で
きない0次に第8図に示した如く850〜450℃で過
時効処理を行なう前に室温近くまで水冷(冷却速度約り
000℃/秒)による急速冷却を行なう場合、水冷とい
う超急速冷却により固溶0の充分な過飽和度が得られ急
速冷却終了時に多数のFe30析出核ができ、次の再加
熱後の過時効処理工程でこれらの析呂核に固溶0が拡散
し短時間でFe50の析出は完了する。この処理ではF
e50の析出核が多数できるので固溶Cの拡散が短い距
離ですみ短時間(例えば1〜8分程麿)の過時効処理で
よいというメリットを持っている。しかしながら析出し
たFe50はへ結晶粒内に微細に多数分散しているため
、析出強化が起り延性を著しく劣化させる。An example of the heat cycle of the conventionally used continuous annealing method is shown in Fig. 181 and Fig. 8. Figure 3 shows an example in which over-aging treatment is carried out for several minutes at 10-400°C after recrystallization annealing, and Figure 8 shows an example in which after recrystallization annealing, water-cooling (approximately 200°C) is performed to near room temperature.
0℃/seo) L, reheat to 850-450℃
In the heat cycle shown in Figure 8, where over-aging treatment is performed for several minutes at
Because it is slow like SEO, the degree of supersaturation of solid solution 0 is small.
Precipitation nuclei of Fe50 are difficult to form, and the rate at which Fe30 is precipitated during the subsequent overaging treatment is extremely slow. As a result, if sufficient overaging time (approximately 5 min or more) is allowed,
Since solid solution O is reduced and the precipitated Fe30 exists in a form that is harmless to ductility, it is possible to manufacture steel sheets with good aging resistance and ductility. When passing a steel plate through a continuous annealing furnace, it is necessary to either slow down the passing speed and lengthen the residence time in the overaging zone, or increase the length of the overaging furnace itself, which increases costs. On the other hand, if the overaging time is set to 6 minutes or less in the cycle shown in Figure 2, the solid solution 0 will not be sufficiently reduced even if the overaging treatment is performed, and the increase in ductility due to softening and the improvement in aging resistance will not occur. Unexpected Zero Next, as shown in Figure 8, when rapid cooling is performed by water cooling to near room temperature (cooling rate approximately 000°C/sec) before overaging treatment at 850 to 450°C, ultra-rapid cooling called water cooling is performed. As a result, a sufficient degree of supersaturation of solid solution 0 is obtained, and a large number of Fe30 precipitate nuclei are formed at the end of rapid cooling, and in the next overaging treatment step after reheating, solid solution 0 diffuses into these precipitated nuclei, and Fe30 precipitates quickly. The precipitation of Fe50 is completed. In this process, F
Since a large number of e50 precipitation nuclei are formed, it has the advantage that the solid solution C can diffuse over a short distance and only requires a short overaging treatment (for example, 1 to 8 minutes). However, since the precipitated Fe50 is finely dispersed in large numbers within the crystal grains, precipitation strengthening occurs and the ductility is significantly deteriorated.
このように第!1図、第8図に示した従来一般的な連続
焼鈍法のヒートサイクルは、上述のような欠点をもって
いた。Like this! The heat cycle of the conventional continuous annealing method shown in FIGS. 1 and 8 has the above-mentioned drawbacks.
これに対しヒートサイクルを変えたり、また成分、熱延
条件を調節するような槌々の改良法が考案されているが
、未だ光分な性能を安定に得ることはできなかった。In response to this, various methods have been devised to improve the hammer, such as changing the heat cycle and adjusting the ingredients and hot rolling conditions, but it has not yet been possible to stably obtain excellent performance.
発明者らは、上記連続焼鈍処理で耐時効性、延性とも、
良好な鋼を製造するため、1重々の実験を行った結果、
連続焼鈍処理過程の急速冷却終了時に、結晶粒内のFe
50を適当な距離間隔で析出させることにより、Fe1
30の析出強化による延性の劣化を伴うことなく、耐時
効性を改善できることを究明した。この発明はFe50
を適正な間隔で析出させるために、より望ましくは結晶
粒径を加味して、とくに急速冷却速度を制限するととも
に・これに過時効温度と最終冷却条件を組合せるという
これまでにない全く新しい発想に由来している。The inventors have found that the continuous annealing treatment improves both aging resistance and ductility.
As a result of repeated experiments in order to produce good steel,
At the end of rapid cooling in the continuous annealing process, Fe in the grains
By precipitating 50 at appropriate distance intervals, Fe1
It has been found that the aging resistance can be improved without deterioration of ductility due to precipitation strengthening of No. 30. This invention is Fe50
In order to precipitate at appropriate intervals, it is more desirable to take into account the grain size, especially to limit the rapid cooling rate, and to combine this with the overaging temperature and final cooling conditions, an entirely new idea that has never existed before. It originates from.
この発明はO+ 0.008〜0.04重量嗟(以下単
に優で示す) Mn + 0.10〜0.801を、N
j O,00894以下において少なくとも0.01
0 nのAノとともに含有する組成になる熱間圧延鋼帯
を、650℃以上の、巻取お温度で巻取ったのちに常法
による酸洗、冷間圧延を経て連続焼鈍するに際して75
0〜900℃の範囲内で10秒以上保持し、このときの
ぞましくは結晶粒度番号を7.6〜8.8に調節する温
度域に加熱し640〜710℃の範囲の過時効前冷却開
始温度に至るまで80秒以上で徐冷することと、引続く
急速冷却、過時効冷却各工程を、820〜440℃の温
度範囲で60〜810秒間の範囲内の保持に供する過時
効処理の温度に応じて該温度TOHに至る急速冷却速度
(VOR’)と、最終冷却速度(VL )を第1図(a
) 、 (b)の斜線領域で示した条件下に進行させる
ことの結合をもって上記線層の解決手段を与え耐時効性
、延性の良好な冷延鋼板の製造を可能にしたものである
。In this invention, O + 0.008 to 0.04 weight (hereinafter simply referred to as excellent), Mn + 0.10 to 0.801, and N
j At least 0.01 below 0,00894
When a hot-rolled steel strip having a composition containing 0 n of A is coiled at a coiling temperature of 650°C or higher, it is pickled by a conventional method, cold rolled, and then continuously annealed.
Hold the temperature within the range of 0 to 900°C for 10 seconds or more, then heat to a temperature range that preferably adjusts the grain size number to 7.6 to 8.8, and then heat to a temperature range of 640 to 710°C before overaging. An over-aging treatment in which slow cooling is performed for 80 seconds or more until the cooling start temperature is reached, and subsequent rapid cooling and over-aging cooling steps are maintained within a temperature range of 820 to 440°C for 60 to 810 seconds. Figure 1 (a) shows the rapid cooling rate (VOR') and final cooling rate (VL) up to the temperature TOH according to the
) and (b), the combination of proceeding under the conditions shown in the shaded area provides a solution to the above-mentioned line layer and makes it possible to manufacture a cold-rolled steel sheet with good aging resistance and ductility.
この発明において鋼中成分量を限定した理由について説
明する。The reason why the amount of components in the steel is limited in this invention will be explained.
Oは、鋼中に固溶状態で存在すると、時効特性の劣化を
引き起すばかりでなく、延性も悪くする点でNと同様に
機能するのでこれらの固溶量を出来るだけ減少すべきで
あり、このため製鋼時溶製後に脱ガスを施して0含有量
を0.00154以下までに減らす方法のほか、Ti
* Nb+Zr IV等等化化物形成元素添加し、固溶
状態の0を減らす方法、さらに連続焼鈍時、急速冷却と
過時効処理を行なうことにより、短時間でFe50とし
て析出させ、固溶0を低減させる方法の8つが考えられ
る。このうち、前2者は固溶0が元来非常に少ないので
、急速冷却や過時効処理を、はとんど必要としないが、
真空脱ガス又は高価な添加元素を使う必要があり、製造
コストの上昇を引き起す。If O exists in a solid solution state in steel, it not only causes deterioration of aging properties but also functions similarly to N in that it also worsens ductility, so the amount of these solid solutions should be reduced as much as possible. Therefore, in addition to degassing after melting during steel manufacturing to reduce the 0 content to 0.00154 or less, Ti
* A method of adding equalizer forming elements such as Nb + Zr IV to reduce 0 in the solid solution state, and by performing rapid cooling and over-aging treatment during continuous annealing, it precipitates as Fe50 in a short time and reduces the 0 in solid solution. There are eight possible ways to do this. Of these, the former two have very little solid solution 0 to begin with, so rapid cooling and over-aging treatment are rarely necessary.
It is necessary to use vacuum degassing or expensive additive elements, causing an increase in manufacturing costs.
これに対し、後者の急速冷却と過時効処理の場には、溶
製コストが最も安いので、過時効時間の短”縮が可能に
なれば低コストで耐時効性延性の良好な鋼板の製造が可
能となる〇
この発明はもちろん後者を利用するわけであり、このた
め0含有量については非常に厳密な制限が必要となる。On the other hand, in the latter case of rapid cooling and over-aging treatment, the melting cost is the lowest, so if it is possible to shorten the over-aging time, it is possible to manufacture steel sheets with good aging resistance and ductility at low cost. This invention naturally utilizes the latter, and therefore very strict restrictions are required on the 0 content.
0の下限を0.008 優としたのはこの値未゛満−の
場合、急速冷却によって得られる過飽和の固溶0量は、
0含有量目体が少ないので非常に小さくなり、その結果
1公租度の短時間過時効ではFeλOの析出が少なく耐
時効性延性が改良され得ない。0の上限を0.041と
したのはより過剰の0の増加は、炭化物系の介在物の増
加と、結晶粒成長を抑制する働きをし、いずれも延性に
とって不利となる上、また0、04 %を越える0の増
加に伴う結晶粒の微細化により過時効前の急速冷却によ
る過飽和度が充分得られず、固溶0の減少すなわち耐時
効性の改善に6分以上の長時間の過時効処理を必要とす
るようになる。以上のようにこの発明ではOの範囲をo
、ooa sから0.04 %の範囲にすることが必要
である。The lower limit of 0 was set to 0.008.If the value is less than this value, the amount of supersaturated solid solution obtained by rapid cooling is
Since the zero content is small, it becomes very small, and as a result, in short-time overaging with a tolerance of 1, the precipitation of FeλO is small and the aging resistance ductility cannot be improved. The reason for setting the upper limit of 0 to 0.041 is that an excessive increase in 0 increases carbide-based inclusions and suppresses grain growth, both of which are disadvantageous for ductility. Due to the refinement of grains associated with an increase in O content exceeding 0.04%, a sufficient degree of supersaturation cannot be obtained by rapid cooling before overaging, and long-term aging of 6 minutes or more is necessary to reduce the solid solution O content, that is, to improve aging resistance. Requires aging treatment. As described above, in this invention, the range of O is
, ooas to 0.04%.
InはSに起因する熱間圧延時のわれを防止するため下
限を0.1噂とし、一方0.130 優を越えるMnの
添加は0の増量と同様連続焼鈍時の結晶粒の微細化の原
因となり、延性、耐時効性にとって不利となる。従って
Inは0.1O〜O,aO*に限定する。The lower limit of In is set at 0.1 in order to prevent cracking during hot rolling caused by S. On the other hand, addition of Mn exceeding 0.130 causes grain refinement during continuous annealing as well as increasing the amount of In. This is disadvantageous for ductility and aging resistance. Therefore, In is limited to 0.1O to O, aO*.
Aノは熱延時に高@(650℃以上)で巻取ることによ
り時効性に有害な固fiNをAjNとして固定するのに
必要でありNを固定するのに最低0.01チ必要である
。A is necessary to fix hard fiN, which is harmful to aging properties, as AjN by winding at a high temperature (650° C. or higher) during hot rolling, and a minimum of 0.01 is required to fix N.
Nは連続焼鈍で製造した鋼板の耐時効性を劣化させ、か
つ粒成長性を抑え、延性を悪くするためできるだけ少な
いほうが望ましく、その上限はo、oosoチであるを
要する。Since N deteriorates the aging resistance of steel sheets manufactured by continuous annealing, suppresses grain growth, and impairs ductility, it is desirable to reduce the amount as much as possible, and the upper limit should be o, ooso.
次に熱間圧延条件について説明する。Next, hot rolling conditions will be explained.
この発明では、スラブを熱間圧延して熱延コイルとする
際のスラブ加熱温度や熱間仕上げ温度はとくに規定する
を要しないが、通常のスラブ加熱条件である1200
N12100℃加熱ばかりでなく、1000〜1ji−
00℃加熱にすることにより、Nの固溶を抑えなお一層
耐時効性の改善が期待できる。また熱延仕上圧延温度は
ムr3点以上(約840℃以上)あれば特に規定しない
。しかし巻取り温度については、固溶Nt−Aノで固定
し無害化してかつ熱延時にOをFe30として巨大に凝
集させることにより、連続焼鈍時の粒成長性と絞り性に
有利な(111)集合組織の発達を促す目的で650℃
以上にすることが必要である。In this invention, the slab heating temperature and hot finishing temperature when hot-rolling a slab to form a hot-rolled coil are not particularly specified, but the normal slab heating conditions are 1200
Not only N12100℃ heating but also 1000~1ji-
By heating to 00°C, solid solution of N can be suppressed and further improvement in aging resistance can be expected. Further, the finish rolling temperature of hot rolling is not particularly specified as long as it is 3 points or more of unevenness (approximately 840° C. or more). However, regarding the coiling temperature, by fixing the solid solution Nt-A to make it harmless and agglomerating O into a huge amount as Fe30 during hot rolling, it is advantageous for grain growth and drawability during continuous annealing (111). 650℃ for the purpose of promoting the development of texture
It is necessary to do the above.
表に素材の成分とともに、本発明σ)最も重要な構成要
因である連続焼鈍処理条件について説明するO′
まず連続焼鈍過程では750〜900℃まで急速加熱し
た後、該温度に10秒以上保持する。The table shows the ingredients of the material as well as the continuous annealing treatment conditions, which are the most important component of the present invention. .
この発明の成分組成の鋼を用いるごと1と、連続焼鈍で
760〜900℃に加熱することとにより、結晶粒径は
粒度番号で8.8程度にまでなるが750℃未満の低温
域に加熱する場合は、再結晶完了後の粒成長が光分でな
いため、その後の急速冷却により固溶0の光分な過飽和
度が得られず過時効処理による結晶粒内へのFe50の
析出が遅れて過時効終了に長時間を要し、一方加熱温度
が900℃を越えまた、粒度番号が7.5未満となると
、結晶粒の粗大化に伴う加工時の肌荒れ(オレンジビー
ル)が発生し、製品として好ましくない。この再結晶温
度域に一10秒以上保持するのは、その温度における粒
成長が完了するのに最低10秒を要するからである・
次に、160〜900℃の再結晶焼鈍温度から急速冷却
開始温度である640〜720℃まで、80秒以上で徐
冷するのは、80秒未満の冷却時間で冷却すると、高温
での焼鈍によりできたr(オーステナイト)相は、急速
冷却により微細なパーライトに変化し、延性に対して不
利になるとともに、α相中の固溶0濃度が焼鈍温度の増
加とともに減少し、過時効処理前の急速冷却によっても
充分な過飽和度が得られず、過時効処理によっても固溶
0が中途半端に残り耐時効性の劣化を招くからである。By using the steel having the composition of this invention and heating it to 760 to 900°C by continuous annealing, the crystal grain size reaches a grain size number of about 8.8, but it is heated to a low temperature range of less than 750°C. In this case, since the grain growth after the completion of recrystallization is not optical, the subsequent rapid cooling does not allow optical supersaturation of solid solution 0, and the precipitation of Fe50 in the crystal grains due to overaging treatment is delayed. It takes a long time to finish overaging, and if the heating temperature exceeds 900°C and the particle size number is less than 7.5, roughness (orange beer) occurs during processing due to coarsening of crystal grains, resulting in poor quality of the product. undesirable as such. The reason why this recrystallization temperature range is maintained for more than 10 seconds is because it takes at least 10 seconds for grain growth to complete at that temperature.Next, rapid cooling is started from a recrystallization annealing temperature of 160 to 900°C. Slow cooling for 80 seconds or more to a temperature of 640 to 720°C is because if the cooling time is less than 80 seconds, the r (austenite) phase created by high-temperature annealing will turn into fine pearlite due to rapid cooling. In addition, the solid solution 0 concentration in the α phase decreases as the annealing temperature increases, and sufficient supersaturation cannot be obtained even with rapid cooling before overaging, resulting in a disadvantageous effect on ductility. This is because the solid solution 0 remains in the middle, resulting in deterioration of aging resistance.
急速冷却前の徐冷終了温度すなわち急速冷却開始温度と
して640〜720℃に限定するのは、以上のように高
温焼鈍によりできたl相をAr1 g態点以下まで冷却
することにより無害化することと、急速冷却温度を64
0〜720℃にすることにより、急速冷却開始時のα(
フェライト)相中の固溶0を最も高いレベルとしく推定
固溶0量;0.0θ8〜θ、QB鴫)急速冷却とそれに
続く過時効処理の効果を最も高めることを目的とする。The reason why the slow cooling end temperature before rapid cooling, that is, the rapid cooling start temperature, is limited to 640 to 720°C is to render the l-phase produced by high-temperature annealing harmless by cooling it to below the Ar1 g state point. and the rapid cooling temperature to 64
By heating the temperature to 0 to 720°C, α(
The purpose is to set 0 solid solution in the ferrite phase as the highest level and to maximize the effect of rapid cooling and subsequent overaging treatment.
次にこの発明の中枢をなす、急速冷却と過時効処理の範
囲について詳しく説明する。Next, the scope of rapid cooling and overaging treatment, which are the core of this invention, will be explained in detail.
急速冷却を行なうことにより、過時効開始時に過飽和の
固溶Oを残し、これにより過時効中にFe30の核が結
晶粒内に形成し、ざらにFe50が成長する。By performing rapid cooling, supersaturated solid solution O is left at the start of overaging, and as a result, Fe30 nuclei are formed within the crystal grains during overaging, and Fe50 grows roughly.
材質に大きな影響を及ぼすFe30の析出状態と固溶O
量は、急速冷却終了時の固溶0の過飽和度で決定される
が、これは急速冷却速度と結晶粒径に負うところが大き
い。Precipitation state of Fe30 and solid solution O have a large effect on material quality
The amount is determined by the degree of supersaturation of the solid solution 0 at the end of rapid cooling, which largely depends on the rapid cooling rate and crystal grain size.
また過時効温度は、所定の短時間の過時効処理中に、粒
内に析出したFe30の核に向って過飽和の固溶0が拡
散析出をいかに効率よく進行させるかを決定する重要な
因子である。In addition, the overaging temperature is an important factor that determines how efficiently supersaturated solid solution 0 diffuses and precipitates toward the Fe30 nuclei precipitated within the grains during a predetermined short-time overaging treatment. be.
また、過時効終了後の室温までの最終冷却は、過時効中
に残った固溶Oを、耐時効性の面で問題にならない程度
まで減少させるために重要である。Furthermore, final cooling to room temperature after overaging is important for reducing solid solution O remaining during overaging to an extent that does not pose a problem in terms of aging resistance.
以上の観点で成分の異なる鋼を実験室的に溶解し、急速
冷却速度、過時効温度、最終冷却速度を種々に変えて、
その効果を調べた。From the above point of view, steels with different compositions were melted in the laboratory, and the rapid cooling rate, overaging temperature, and final cooling rate were varied.
We investigated its effects.
(実験1)
供試材は、鋼ム(Q + 0.01101、Mn +
0.189G、P : 0.018優、S + 0.0
10係、Az:o、oaa i N +0.0041
優)及び鋼B (,0: 0.0581!、、Mn ;
o、g’y・優、P : 0.011優、S + 0
.009優、Alj 0.085優、N I 0.00
891 )の2鋼種を、実験室的に真空溶解した。各供
試材は熱延終了後、700℃の炉中に2時間装入保持し
、炉冷して熱延時コイル巻取りに相当する処理を行った
。(Experiment 1) The test material was steel laminate (Q + 0.01101, Mn +
0.189G, P: 0.018 Excellent, S + 0.0
Section 10, Az: o, oaa i N +0.0041
Excellent) and Steel B (,0: 0.0581!,,Mn;
o, g'y・excellent, P: 0.011 excellent, S + 0
.. 009 Excellent, Alj 0.085 Excellent, N I 0.00
891) were vacuum melted in the laboratory. After hot rolling, each test material was placed in a furnace at 700° C. for 2 hours, cooled in the furnace, and subjected to a process equivalent to coil winding during hot rolling.
酸洗、冷延後、鋼Aについて第4図第6図に示すヒート
サイクルで実験室的に連続焼鈍相当の熱処理を行った0
急速冷却は660℃を開始点として過時効温度までVO
R: 10〜b
却する場合、また室温まで水冷(冷却速度約り000℃
/秒)した後、再加熱する場合のそれぞれについて、8
00℃〜500℃の過時効温度(TOR)に180秒保
持し、その後室温までδ℃/秒で徐冷した。なお、この
実験における鋼Aの粒度番号は8.8であった。After pickling and cold rolling, Steel A was subjected to heat treatment equivalent to continuous annealing in the laboratory using the heat cycles shown in Figures 4 and 6.
Rapid cooling starts from 660℃ and VO up to the overaging temperature.
R: 10~b When cooling, water cooling to room temperature (cooling rate approximately 000℃)
/ seconds) and then reheated, 8
The overaging temperature (TOR) of 00°C to 500°C was maintained for 180 seconds, and then slowly cooled to room temperature at a rate of δ°C/second. Note that the grain size number of Steel A in this experiment was 8.8.
また鋼Bについても同様に、過時効温度をとくに850
℃としこの過時効処理前の冷却速度を10〜b
を行った〇
上記の連続焼鈍相当の熱処理を行った供試材に0.8−
の調質圧延を施して、材質を調べた。Similarly, for steel B, the overaging temperature was set to 850.
℃ and the cooling rate before over-aging treatment was 10-b.
The material was examined by temper rolling.
材質としては、耐時効性の尺度として人工、延性の尺度
として全伸びを調べた。第6図(〜lω)にその結果を
示す。0内に示したのが鋼Bの結果であり、その他は鋼
ムの結果である。この発明に従う鋼Aを用い、かつ急速
冷却条件として80〜b
度条件が図中に示した図形領域内にある時、AI=4.
5ψ−以下、全伸び:46チ以上が得られ、耐時効性、
延性の良好な鋼板が”製造可能となる。Regarding the material, artificiality was examined as a measure of aging resistance, and total elongation was examined as a measure of ductility. The results are shown in FIG. 6 (~lω). The results shown within 0 are the results for steel B, and the others are the results for steel. When steel A according to the present invention is used and the rapid cooling condition is 80 to b degrees within the graphic region shown in the figure, AI=4.
5ψ- or less, total elongation: 46 inches or more, aging resistance,
It becomes possible to manufacture steel sheets with good ductility.
これに対し比較例の鋼Bでは、急速冷却速度を種々に変
えても、良好な材質は得られていない。On the other hand, in Steel B of Comparative Example, good material quality was not obtained even if the rapid cooling rate was varied.
これは0が高いために、連続焼鈍時の結晶粒成長が劣り
J(粒度番号9.2)急冷、過時効処理によるFe50
の析出と固溶0の減少が充分進まず、AH1全伸びが劣
ることになったものと推定される。This is because the crystal grain growth during continuous annealing is poor due to the high J (grain size number 9.2) Fe50 due to rapid cooling and overaging treatment.
It is presumed that the precipitation of 0 and the reduction of solid solution 0 did not progress sufficiently, resulting in poor AH1 total elongation.
!ilAで急速冷却速度が極端に速い(水冷工約goo
o℃/秒)場合急冷による固溶0の過飽和度が充分に得
られ、Fe50が微細に析出するので、AIは低いレベ
ルにあり良好であるがFe50が微細に析出しすぎるた
めEjは逆に劣化する。また冷却速度が極端に遅い(8
0℃/秒未満)の場合、急速冷却終了時の固溶0の過飽
度が小さいため過時効中にFe50の析出が起りに<<
、また起ったとしても粗に析出するので、結果的に固溶
0が多く残り、Aiは高くまたEjも劣る。! Rapid cooling speed is extremely fast with ilA (water cooling technology goo
o℃/sec), the degree of supersaturation of solid solution 0 is sufficiently obtained by rapid cooling, and Fe50 is finely precipitated, so AI is at a low level and good, but since Fe50 is too finely precipitated, Ej is on the contrary. to degrade. Also, the cooling rate is extremely slow (8
(less than 0°C/sec), the supersaturation degree of solid solution 0 at the end of rapid cooling is small, so precipitation of Fe50 occurs during overaging.
, even if it occurs, it precipitates coarsely, resulting in a large amount of solid solution 0 remaining, resulting in high Ai and poor Ej.
これに対し、急速冷却速度が80〜b
で力)つ急速冷却速度と過時効温度が第6図a + b
の図形範囲内にあるとき材質(AI、全伸び)が最もす
ぐれる。なお、鋼ムの結晶粒度番号は7.9であり、A
I、Ejとも適正な場合の結晶粒内のEe3Qの平均距
離は1.1〜1.6μであった。On the other hand, when the rapid cooling rate is 80~b, the rapid cooling rate and overaging temperature are as shown in Figure 6 a + b.
The material quality (AI, total elongation) is the best when it is within the figure range. In addition, the grain size number of the steel sheet is 7.9, and A
When both I and Ej were appropriate, the average distance of Ee3Q within the crystal grain was 1.1 to 1.6 μ.
なお急速冷却速度が80〜b
域の場合、急速冷却終了時の固溶0の過飽和度がやや小
さいため、Fe50の析出核の密度が粗く、固溶0の減
少と、それに伴うye3oの成長のためには、過時効温
度として、第6図a s bに示した如く、400℃前
後がより望ましい。これに対し、急速冷却速度が70〜
WOO℃/秒の場合、急速冷却終了時の固溶0の過飽和
度が高く、Fe30の析出核會度が大きいので、a50
’c前後の低温度で、固溶Oの減少とそれに伴うFe5
0の成長が起る。一方該急速冷却速度(70〜b
時効温度を400℃前後とやや高くすると、理由は明ら
かではないが、AIがやや高くなる。When the rapid cooling rate is in the 80~b range, the degree of supersaturation of solid solution 0 at the end of rapid cooling is somewhat small, so the density of Fe50 precipitation nuclei is coarse, resulting in a decrease in solid solution 0 and the accompanying growth of ye3o. For this reason, it is more desirable that the overaging temperature be around 400°C, as shown in FIG. 6, a and b. On the other hand, the rapid cooling rate is 70~
In the case of WOO℃/sec, the degree of supersaturation of solid solution 0 at the end of rapid cooling is high, and the degree of precipitation nuclei of Fe30 is large, so a50
At low temperatures around 'c, a decrease in solid solution O and accompanying Fe5
0 growth occurs. On the other hand, when the rapid cooling rate (70-b) is set to a slightly higher aging temperature of around 400°C, the AI becomes slightly higher, although the reason is not clear.
この発明の急速冷却速度範囲でも、過時効温度が450
℃以上と高い場合や800℃と低い場合には、材質が劣
る。この理由は、前者は過時効温度が高いためにその温
度での平衡固溶0量が高く室温まで徐冷しても固溶0量
が高いまま残るためであり、また後者は、過時効温度が
低いために短時間では過時効が完了しなかったものと推
定されるO
なお、この実験に併せて、過時効開始温度に比べ同終了
温度が低い場合についても実験をしたが一過時効開始温
度と同終了温度との差が50℃以内であれば、過時効開
始温度と同終了温度の平均値を代表の過時効温度とする
ことによりこの発明の所期した目的に適合する。Even in the rapid cooling rate range of this invention, the overaging temperature is 450
If the temperature is as high as 800°C or higher, or as low as 800°C, the quality of the material is poor. The reason for this is that in the former case, the overaging temperature is high, so the equilibrium solid solution 0 amount at that temperature is high and the solid solute 0 amount remains high even if slowly cooled to room temperature, and in the latter case, the overaging temperature It is presumed that the overaging was not completed in a short time because of the low temperature. If the difference between the temperature and the end temperature is within 50°C, the intended purpose of the present invention can be met by setting the average value of the overaging start temperature and the overaging end temperature as the representative overaging temperature.
過時効処理時間の効果は、60秒以下では効果が小さく
、また、21O秒を越えると、その効果が飽和されるば
かりでなく、運転スピードを落すか、過時効処理帯を長
くする必要があり大幅なコストアップにつながる不利を
伴う。The effect of overaging treatment time is small if it is less than 60 seconds, and if it exceeds 210 seconds, not only is the effect saturated, but it is also necessary to reduce the operating speed or lengthen the overaging treatment zone. This has the disadvantage of significantly increasing costs.
次に過時効条件と最終冷却速度との関連を調べるため以
下の実験を行った。Next, the following experiment was conducted to investigate the relationship between overaging conditions and final cooling rate.
(実験2)
実験1の鋼Aを用い、実験1と同条件の熱間圧延、冷間
圧延の後、連続焼鈍相当のサイクルで熱処理を施した。(Experiment 2) Steel A from Experiment 1 was hot rolled and cold rolled under the same conditions as Experiment 1, and then heat treated in a cycle equivalent to continuous annealing.
連続焼鈍サイクルとしては、急速冷却開始までは第4図
のサイクルと同じであり、それに続く660℃からの急
速冷却をこの発明に従って80゜60.100.および
8oo℃/秒に分け、かつそれに続く過時効処理として
、過時効温度を第7図の図形領域内の温度範囲で行ない
(過時効時間150秒)さらに室温までの最終冷却を8
0℃/秒以下で種々に変化させて、熱処理をした。調質
圧延後の材質を第7図にまとめてプロットした。The continuous annealing cycle is the same as the cycle shown in Fig. 4 until the start of rapid cooling, and then the rapid cooling from 660°C is repeated at 80°, 60°, and 100° according to the present invention. and 800°C/sec, and as a subsequent overaging treatment, the overaging temperature was carried out within the temperature range within the graphic area of Figure 7 (overaging time 150 seconds), and the final cooling to room temperature was performed for 800°C/sec.
Heat treatment was performed at various rates below 0°C/sec. The material properties after temper rolling are summarized and plotted in FIG.
急速冷却速度、過時効温度を適切に設定しても、過時効
温度と最終冷却速度の関係が第7図の図形内に入らない
と耐時効性、延性とも良好な鋼板は製造できない。そし
て最終冷却速度が2℃/秒未満では、通板速度の低下ま
たは建設費の増加につながるので好ましくない。Even if the rapid cooling rate and overaging temperature are set appropriately, unless the relationship between the overaging temperature and the final cooling rate falls within the diagram of FIG. 7, a steel plate with good aging resistance and ductility cannot be manufactured. If the final cooling rate is less than 2° C./sec, it is not preferable because it leads to a decrease in the sheet passing rate or an increase in construction costs.
なお・このように材質が良好となる範囲第1図の(a)
、 (b)は、鋼の成分及び連続焼鈍時の焼鈍温度に
2いては結晶粒度番号を、限定することにより始めて達
成される。In addition, the range where the material quality is good in this way is (a) in Figure 1.
(b) can only be achieved by limiting the composition of the steel, the annealing temperature during continuous annealing, and the grain size number.
以上のように素材成分、特にO%MnttB)14節し
たムノキルド鋼を用いて、連続焼鈍の際に750〜90
0℃の温度に加熱し、ひいては結晶粒度番号を7.6〜
8.8に調節することにより、それに続く急速冷却速度
、過時効温度、及び最終冷却速度を、第1図(11)
、 (b)の斜線領域内に選べば、耐時効性、延性の良
好な冷延鋼板の製造が可能となる。As mentioned above, using the material composition, especially O%MnttB) 14-node munokilled steel, 750 to 90
Heating to a temperature of 0°C, the grain size number is 7.6~
8.8, the subsequent rapid cooling rate, overaging temperature, and final cooling rate are as shown in Figure 1 (11).
, (b), it becomes possible to manufacture a cold-rolled steel sheet with good aging resistance and ductility.
なお、実用の連続焼鈍ラインにおいてこの発明に従う急
速冷却を実現するためには、コイル通板時に板面にガス
を吹付ける強制ガス冷却法(冷却速変80〜80℃/秒
)、温度の低いロールに板面を接触させ、冷却させる方
法(冷却速度80〜b
板面に吹付けて冷却する方法(冷却速度50〜b
実施例1
表1に示した成分の異なる4alの鋼を転炉で溶製した
。In order to achieve rapid cooling according to the present invention in a practical continuous annealing line, it is necessary to use a forced gas cooling method (cooling rate variable 80 to 80°C/sec), which blows gas onto the sheet surface during coil threading, and a low temperature method. A method of cooling the plate surface by bringing it into contact with a roll (cooling rate 80~b) A method of cooling the plate surface by spraying it (cooling rate 50~b) Example 1 4Al steels with different components shown in Table 1 were heated in a converter. Melted.
これらの鋼は連続鋳造により板厚2oosmのスラブと
した。なおこれらの鋼は転炉出鋼時の吹止め0値が光分
に低いので脱ガスを施すことなく出鋼後連続鋳造したが
、吹止めの0値が高い場合脱ガスを施してO量を関節し
てもよいのはいうまでもない。These steels were made into slabs with a thickness of 2 oosm by continuous casting. These steels were continuously cast after tapping without degassing because the zero value of the blowstop at the time of tapping from the converter was extremely low. However, if the zero value of the blowstop was high, degassing was performed to reduce the O content. It goes without saying that you can join the two.
これらのスラブを再加熱後、熱間圧延で2.811sに
圧延し680〜720℃で巻取った。次に、酸洗後冷間
圧延により0.8118厚の冷延コイルとし、かくして
得られた冷延鋼板を連続焼鈍した0加熱速度約15℃/
秒で710〜920℃まで加熱し、80秒保持後660
℃まで50秒で徐冷した。After reheating these slabs, they were hot rolled to 2.811 s and wound up at 680 to 720°C. Next, a cold-rolled coil with a thickness of 0.8118 was obtained by cold rolling after pickling, and the cold-rolled steel sheet thus obtained was continuously annealed at a heating rate of about 15°C/
Heat to 710-920℃ in seconds, hold for 80 seconds, and then heat to 660℃.
It was slowly cooled to ℃ in 50 seconds.
660℃から種々の冷却速度で種々の過時効温度まで冷
却し、該温度に60秒から810秒間にわたり保持して
その後約り℃/秒で室温まで冷却した。また比較として
、650℃から室温まで水冷し再加熱して過時効する場
合も併せて調べた。It was cooled from 660° C. at various cooling rates to various overage temperatures, held at that temperature for 60 seconds to 810 seconds, and then cooled to room temperature at about 1° C./second. For comparison, a case of overaging by cooling with water from 650° C. to room temperature and then reheating was also investigated.
その後0.8優のスキンパスを施し材質を調べた0なお
冷却速度80℃/秒未満は実ラインの強制ガスジェット
冷却法によりまた80℃/秒以上及び水冷(gooo℃
/秒)は、実験用の連続焼鈍用ラインで焼鈍した。表8
に結果を示す。After that, a skin pass of 0.8% was applied and the material was examined.If the cooling rate is less than 80℃/sec, we will use the forced gas jet cooling method on the actual line.
/sec) was annealed on an experimental continuous annealing line. Table 8
The results are shown in
第 3 表
成分、焼鈍温度がこの発明の限定範囲を外れる調香の鋼
は表8に示す如く結晶粒度番号が本発明範囲外にある。Table 3 Perfume-tuning steels whose components and annealing temperatures are outside the scope of the present invention have grain size numbers outside the scope of the present invention, as shown in Table 8.
但し調香8の鋼は、結晶粒度番号は7.6とこの発明の
範囲に入るが、0が0.0071と低すぎるため範囲外
にある。これによるとこの発明の成分組成になる鋼板を
、この発明の連続焼鈍条件で処理すれば耐時効性延性と
もいずれもすぐれた冷延鋼板を製造できることが明らか
である。However, the steel of Perfume 8 has a grain size number of 7.6, which falls within the range of the present invention, but 0 is too low, 0.0071, so it is outside the range. According to this, it is clear that if a steel plate having the composition of the present invention is treated under the continuous annealing conditions of the present invention, a cold rolled steel plate with excellent aging resistance and ductility can be produced.
以上のようにこの発明は、素材の成分と連続焼鈍時の焼
鈍温度を限定することについては結晶粒度番号を7.5
〜8.8の範囲に制限した上でさらにこれに連続焼鈍時
の急速冷却速1度と、過時効温度、最終冷却速度との適
切な組合せによって耐時効性、延性とも良好な鋼を製造
するという従来にない全く新しい効果を挙げることがで
きる。As described above, in this invention, the grain size number is set to 7.5 in terms of limiting the ingredients of the material and the annealing temperature during continuous annealing.
After limiting the temperature to a range of ~8.8, a steel with good aging resistance and ductility can be produced by appropriately combining a rapid cooling rate of 1 degree during continuous annealing, an overaging temperature, and a final cooling rate. It is possible to bring about completely new effects that have never existed before.
第1図(a) 、 (b)はこの発明に従い過時効温度
と急速冷却速度ならびに最終冷却速度の限定範囲を示す
図表、
第LiA図、第8図は従来の連続焼鈍におけるヒ−トサ
イクルの例を示す縞図、
第4図、第す図は実験1で用いられた連続焼鈍相当の熱
サイクルの線図、
第6図(a) 、 (b)は、AIと全伸びに及ぼす急
速冷却速度および過時効温度の効果を示す図表であり、
第7図は実験2の結果をAI、全伸びに及ぼす過時効温
度、最終冷却速度の効果について示す図表である〇
特許出願人 川崎製鉄株式会社
第1図(aン
、M84効遇贋T、祠で)
第1図(b)
姐吟幼シ2度−2(’Cう
第2図
第3図Figures 1 (a) and (b) are charts showing the limited ranges of overaging temperature, rapid cooling rate, and final cooling rate according to the present invention, and Figures LiA and 8 are diagrams showing the heat cycle in conventional continuous annealing. Striped diagrams showing examples; Figures 4 and 5 are diagrams of thermal cycles equivalent to continuous annealing used in Experiment 1; Figures 6 (a) and (b) are rapid cooling effects on AI and total elongation. 2 is a diagram showing the effect of rate and overaging temperature;
Figure 7 is a chart showing the results of Experiment 2 regarding the effects of AI, overaging temperature on total elongation, and final cooling rate. At the shrine) Figure 1 (b)
Claims (1)
10〜0.80重量−を、N ; 0.008重量−以
下において少くとも0.010重量−のAjとともに含
有する組成になゐ熱間圧延鋼帯を、その熱間圧延終了後
660℃以上の温度で巻取り、しかる後常法に従う酸洗
、冷間圧延を経て、連続焼鈍を施すに際して、 750〜900℃の範囲内の温度に急速加熱し、10秒
間以上にわたる保持となる焼鈍過程を経て、その保持後
、640〜7110℃の範囲の温度に至るまで80秒間
以上にわたる徐冷に引続き急速冷却を加える前処理段階
、880°〜440°0の範囲の温度で60〜810秒
間にわたる保持となる過時効処理段階および最終冷却段
階との各過程を、 上記880〜440℃の範囲から選んだ過時効処理温度
(TOR)に厄じて、前処理段階における後段急冷過程
の急速冷却速度(VOR)と−最終冷却段階におけ・る
冷却速度(VL)とについて、第1図(〜、(b)の斜
線領域で示した条件下に進行させる ことからなる、耐時効性と延性の良好な、冷延鋼板製造
方法。 2 焼鈍過程が、冷延鋼板の結晶粒度を粒度番号で7.
5〜8.8に調節する段階である、l記載の方法。[Claims] L 010.008 to 0.04 weight, Mn + 0.
10 to 0.80% by weight of N; 0.008% by weight or less together with Aj of at least 0.010% by weight, and heated to 660°C or more after hot rolling. After that, the material is wound up at a temperature of and, after holding, a pretreatment step of slow cooling for 80 seconds or more to a temperature in the range of 640 to 7110°C, followed by rapid cooling, and holding for 60 to 810 seconds at a temperature in the range of 880 to 440°C. The rapid cooling rate (TOR) of the subsequent quenching process in the pretreatment stage ( VOR) and the cooling rate (VL) in the final cooling stage. A method for producing a cold rolled steel sheet. 2. The annealing process changes the grain size of the cold rolled steel sheet to 7.
5 to 8.8, the method according to I.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP10166682A JPH0244890B2 (en) | 1982-06-14 | 1982-06-14 | TAIJIKOSEITOENSEINORYOKONA * REIENKOHANSEIZOHOHO |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP10166682A JPH0244890B2 (en) | 1982-06-14 | 1982-06-14 | TAIJIKOSEITOENSEINORYOKONA * REIENKOHANSEIZOHOHO |
Publications (2)
Publication Number | Publication Date |
---|---|
JPS58217638A true JPS58217638A (en) | 1983-12-17 |
JPH0244890B2 JPH0244890B2 (en) | 1990-10-05 |
Family
ID=14306690
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP10166682A Expired - Lifetime JPH0244890B2 (en) | 1982-06-14 | 1982-06-14 | TAIJIKOSEITOENSEINORYOKONA * REIENKOHANSEIZOHOHO |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPH0244890B2 (en) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0171197A2 (en) * | 1984-07-09 | 1986-02-12 | Nippon Steel Corporation | Process for producing, by continuous annealing, soft blackplate for surface treatment |
US5074924A (en) * | 1989-06-21 | 1991-12-24 | Nippon Steel Corporation | Process for producing galvanized, non-aging cold rolled steel sheets having good formability in a continuous galvanizing line |
-
1982
- 1982-06-14 JP JP10166682A patent/JPH0244890B2/en not_active Expired - Lifetime
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0171197A2 (en) * | 1984-07-09 | 1986-02-12 | Nippon Steel Corporation | Process for producing, by continuous annealing, soft blackplate for surface treatment |
US5074924A (en) * | 1989-06-21 | 1991-12-24 | Nippon Steel Corporation | Process for producing galvanized, non-aging cold rolled steel sheets having good formability in a continuous galvanizing line |
Also Published As
Publication number | Publication date |
---|---|
JPH0244890B2 (en) | 1990-10-05 |
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