JPS62139823A - Production of cold rolled steel sheet for deep drawing - Google Patents

Abstract

PURPOSE:To inexpensively produce a cold rolled steel sheet for deep drawing having the small intra-surface anisotropy of an r value and slow aging characteristic by subjecting a specifically composed steel successively to soaking, hot rolling, quick cooling, coiling, cold rolling, and continuous annealing under specific conditions. CONSTITUTION:The slab contg., per weight %, 0.005-0.0050% C, 0.001-0.50% Mn, <0.01% S, 0.0005-0.0070% N, <=0.02% acid solAl, and at least one kind of Ti and Zr in the range of 3.4XN+4(C-0.0015)<=Ti+48/91Zr<3.4XN+4.C except the same contained in the form of oxide and sulfide and consisting of the balance iron and inevitable impurities is soaked at >=1,100 deg.C. The slab is then hot rolled at 700-880 deg.C finish temp. and is rolled down at >=30% of the sheet thickness after the rough hot rolling in the temp. region of the finishing temp. +100 deg.C. The rolled sheet is quickly cooled down to 300-550 deg.C at >=5 deg.C/sec upon completion of the hot rolling and is coiled as it is at 300-550 deg.C. The sheet is further cold rolled at 70-95% draft and is continuously annealed at 680-850 deg.C.

Description

【発明の詳細な説明】 （産業上の利用分野） 本発明は、耐常温歪時効性、耐２次加工脆性および耐肌
荒れ性が良好で、かつ、絞り性の指数であるｒ値の面内
異方性が小さい、深絞り用冷延鋼板の安価な製造方法に
関するものである。Detailed Description of the Invention (Field of Industrial Application) The present invention has good room temperature strain aging resistance, secondary work brittleness resistance, and skin roughening resistance, and has an in-plane r value that is an index of drawability. The present invention relates to an inexpensive manufacturing method for cold-rolled steel sheets for deep drawing with low anisotropy.

（従来の技術） 従来、深絞り用冷延鋼板は、低炭素アルミキルド鋼を箱
焼鈍して製造していた。ところが近年、深絞り用冷延鋼
板にも生産性向上等のために連続焼鈍法が広く用いられ
るようになり、それに伴って、従来材の低炭素アルミキ
ルド鋼では必要な材料特性が容易には得られないと言う
問題が生じてきた。(Prior Art) Conventionally, cold rolled steel sheets for deep drawing have been manufactured by box annealing low carbon aluminum killed steel. However, in recent years, continuous annealing has become widely used for cold-rolled steel sheets for deep drawing in order to improve productivity, and as a result, it has become difficult to obtain the necessary material properties with conventional low-carbon aluminum-killed steel. The problem has arisen that it cannot be done.

このような問題に対処すべく、従来にあっても、極低炭
素鋼にＴｉやＺｒのような炭窒化物形成元素を添加した
材料が数多くＲ案されている。In order to cope with such problems, many R plans have been proposed in the past, in which carbonitride-forming elements such as Ti and Zr are added to ultra-low carbon steel.

例えば、特公昭４４−１８０６６号公報にはＴｉ添加−
深絞り用冷延鋼板の製造法が開示されている。これは、
Ｃ：　０．００１〜０．０２０％としたうえでＴｉ　０
．２〜０．５、かつＴｉ≧４ｘＣの量のＴｉを添加する
ことにより鋼中の炭素・窒素を全て炭窒化物として固定
した、いわゆるインタースティシャル・フリー（ｒｎｔ
ｅｒｓｔｉｔｉａｌ−Ｆｒｅｅ）鋼に関するもので、下
記のような長所がみられる。For example, in Japanese Patent Publication No. 44-18066, Ti is added.
A method of manufacturing a cold rolled steel sheet for deep drawing is disclosed. this is,
C: 0.001 to 0.020% and then Ti 0
．． So-called interstitial free (rnt
erstitial-free) steel, and has the following advantages.

（ｉ）深絞り用冷延鋼板が安定して製造できる。(i) Cold-rolled steel sheets for deep drawing can be stably produced.

（１１）固溶炭素・固溶窒素が残留しないので、低炭素
鋼では常に問題になる常温ひずみ時効が生じない。(11) Since no solid solute carbon or nitrogen remains, room temperature strain aging, which is always a problem with low carbon steel, does not occur.

しかし、その反面、次のような短所もみられる。However, on the other hand, there are also the following disadvantages.

（１）鋼中の炭素・窒素を完全に炭窒化物として固定す
るために、常にＴｉが過剰になるように添加しなければ
ならず、製造コストが高い。(1) In order to completely fix carbon and nitrogen in steel as carbonitrides, Ti must always be added in excess, resulting in high manufacturing costs.

（２）固溶炭素による結晶粒界の強化効果がないため、
２次加工脆性を生じやすくなる。(2) Since there is no strengthening effect of grain boundaries due to solid solution carbon,
Secondary processing embrittlement is likely to occur.

（３）　Ｔｉの添加量が増すのに伴って再結晶温度が高
くなり、焼鈍温度も高くなり、熱エネルギー・コストが
大きくなる。また、高温焼鈍を行うと、ヒート・バック
リングや、焼鈍炉内のハースロールの表面に酸化物等が
付着して生じるロールすり傷の発生が多くなり、生産性
が著しく劣化する。(3) As the amount of Ti added increases, the recrystallization temperature increases, the annealing temperature also increases, and the thermal energy cost increases. Furthermore, when high-temperature annealing is performed, heat buckling and roll scratches caused by adhesion of oxides and the like to the surface of the hearth roll in the annealing furnace increase, resulting in a significant deterioration of productivity.

上記（２）の短所に対しては、Ｂを添加して粒界を強化
する方法が特開昭５７−３５６６２号公報等により開示
されている。また上記（３）の短所に対しては、連続鋳
造の引き抜き速度や熱間圧延条件等を制御することによ
り再結晶温度を低下せしめる方法が特公昭５８−５７４
９０号公報等により開示されている。To address the above disadvantage (2), a method of strengthening grain boundaries by adding B is disclosed in Japanese Patent Application Laid-Open No. 57-35662. In addition, to solve the above disadvantage (3), a method of lowering the recrystallization temperature by controlling the drawing speed of continuous casting, hot rolling conditions, etc. was proposed in Japanese Patent Publication No. 58-574
This is disclosed in Publication No. 90 and the like.

しかし、いずれにしろ、上記１１１の短所は解消されて
いない。However, in any case, the disadvantages of 111 described above have not been resolved.

このような状況において、Ｔｉの添加量を少なくすると
再結晶温度が低下することに注目し、Ｃ０１０２０％以
下とするとともにＴｉ　Ｏ，００５〜０．０８％であっ
てかつＴｉとＣとの重量％の比が４未満になるようにＴ
ｉ添加量を調整した極低炭素−Ｔｉ添加鋼を素材として
用いた、プレス成形用冷延鋼板の製造法が、特開昭５３
−１３７０２１号公報により開示されている。しかしな
がら、絞り性の指数であるｒ値ならびに全伸びも深絞り
用としては不十分なものしか得られていない。これは、
この製造法が単にＴｉ／Ｃを４未満に限定しただけであ
るため、添加されたＴｉの大部分が酸化物や硫化物にな
ってしまうで、実際には、鋼中に多量の固溶炭素が存在
するため、焼鈍後に良い特性が得られないものと考えら
れる。In this situation, it is noted that the recrystallization temperature decreases when the amount of Ti added is reduced, and the amount of Ti added is set to 20% or less, and the weight percentage of Ti and C is set to 0.005% to 0.08% and the weight percentage of Ti and C is reduced. T so that the ratio of is less than 4
A method for manufacturing cold-rolled steel sheets for press forming using ultra-low carbon-Ti added steel with an adjusted amount of i added was disclosed in JP-A-53
It is disclosed in the publication No.-137021. However, the r value, which is an index of drawability, and the total elongation are insufficient for deep drawing. this is,
Since this manufacturing method simply limits the Ti/C ratio to less than 4, most of the added Ti becomes oxides and sulfides, and in reality, a large amount of solid solute carbon is present in the steel. It is thought that due to the presence of , good properties cannot be obtained after annealing.

また熱間圧延時の粒成長も考慮せず、５５０〜７００℃
と高温巻取りを行っている。Also, without considering grain growth during hot rolling,
and high-temperature winding.

これに対して、特開昭５９−６７３２２号公報は、極低
炭素−Ｔｉ添加鋼のスラブを低温で均熱し熱間圧延する
とＴｉｌとＣ量の関係ではなく　、Ｔｉｆｆ１と（Ｎ＋
５）ｆｆｉの関係で深絞り性が決定されるとの考え方に
もとづいた深絞り用冷延鋼板の製造法が開示している。On the other hand, JP-A No. 59-67322 discloses that when a slab of ultra-low carbon-Ti added steel is soaked at low temperature and hot-rolled, the relationship between Tiff1 and (N+
5) A method for producing cold-rolled steel sheets for deep drawing is disclosed based on the idea that deep drawability is determined by the relationship of ffi.

しかし、この製造法ではスラブを１１００℃以下で均熱
しなければならず、スラブ加熱時の温度むらが顕著にな
り、その後の熱間圧延等の条件がスラブの部位によって
異なり、製品特性のコイル内変動の原因となり、品質管
理上好ましくない。However, with this manufacturing method, the slab must be soaked at a temperature of 1100°C or less, resulting in significant temperature unevenness during heating of the slab, and conditions such as subsequent hot rolling vary depending on the part of the slab. This causes fluctuations and is unfavorable in terms of quality control.

また、特開昭６０−９８３０号公報より開示された製造
法においては、酸化物や硫化物となってしまうＴｉを考
慮に入れ、鋼中窒素を窒化物として固定するのに足りる
だけのＴｉを添加する。しかし、固溶炭素が多いとｒ値
が高くとも、ｒ値の鋼板面内での異方性が大きく、絞り
加工には好ましくない。In addition, in the manufacturing method disclosed in JP-A No. 60-9830, sufficient amount of Ti is added to fix the nitrogen in the steel as nitrides, taking into consideration Ti that would otherwise become oxides and sulfides. Added. However, if there is a large amount of solid solute carbon, even if the r value is high, the anisotropy of the r value within the plane of the steel sheet is large, which is not preferable for drawing.

また、熱間圧延の諸条件の重要性について何ら認識して
いない。Furthermore, they do not recognize the importance of hot rolling conditions.

Ｚｒを添加したものについても同様のことがあてはまる
。The same applies to those to which Zr is added.

（発明が解決しようとする問題点） したがって、本発明の目的とするところは、Ｔｉあるい
はＺｒの微量添加にもかかわらず、ｒ値の面内異方性が
小さい深絞り用冷延鋼板の安価な製造方法を提供するこ
とである。(Problems to be Solved by the Invention) Therefore, the object of the present invention is to provide an inexpensive cold-rolled steel sheet for deep drawing that has small in-plane anisotropy of the r value despite the addition of a small amount of Ti or Zr. The purpose of this invention is to provide a manufacturing method.

さらに、本発明の別の目的は、耐常温歪時効性、耐２次
加工脆性および耐肌荒れ性が良好である深絞り用冷延鋼
板の安価な製造方法を提供することである。Furthermore, another object of the present invention is to provide an inexpensive method for producing a cold-rolled steel sheet for deep drawing that has good room temperature strain aging resistance, secondary work brittleness resistance, and roughening resistance.

（問題点を解決するための手段） ところで、ＩＦ系のＴｉ添加鋼を素材に用いると深絞り
性の良好な冷延鋼板を製造できる理由として、従来から
幾多の説が提案されてきている。これらはだいたい次の
２点に集約される。すなわち、深絞り性に好ましい再結
晶集合組織が発達するのは、（１）固溶Ｃ・固溶Ｎがな
い状態で冷間圧延・再結晶させるから、 （２）微細なＴｉの炭窒化物が存在する状態で、冷間圧
延・再加熱させるから の２つである。しかし、上記（１１に対しては、固溶Ｃ
・固溶Ｎのきわめて少ない純鉄では決して深絞り性に好
ましい再結晶集合組織が得られないし、また（２）に対
しては、熱延板に熱処理等を施して、析出物を粗大化さ
せると更に深絞り性が向上すると言う事実があり、これ
ら２つの説がまだまだ不完全なことを示している。(Means for Solving the Problems) By the way, a number of theories have been proposed in the past as to why cold-rolled steel sheets with good deep drawability can be produced when IF-based Ti-added steel is used as a raw material. These can roughly be summarized into the following two points. In other words, a recrystallized texture favorable for deep drawability develops because (1) cold rolling and recrystallization is performed in the absence of solid solute C and solute N, and (2) fine Ti carbonitrides. Two reasons are that the steel is cold rolled and reheated in the presence of However, for the above (11), solid solution C
・Pure iron with extremely low solute N will never have a recrystallized texture that is favorable for deep drawability, and for (2), the hot-rolled sheet is subjected to heat treatment to coarsen the precipitates. There is also the fact that deep drawability is further improved, which shows that these two theories are still incomplete.

ここに、本発明者らは、いくつかの実験事実から、次の
ような推論に達した。つまり、深絞り性に好ましい再結
晶集合組織を得るには、（ｉ）熱延板すなわち冷間圧延
前の結晶粒径が十分少さいこと （１１）再結晶時の固溶Ｃ・固ｉ８Ｎが十分少ないこと （ｉｉｉ　）再結晶温度が低いこと の３つの条件を満たすことが必要である。ただし、（ｉ
ｉ　）と（ｉｉｉ　）の間には補完的な関係がある。つ
まり、再結晶温度が十分低ければ、固溶Ｃ・固溶Ｎがあ
っても、また逆に、固溶Ｃ・固溶Ｎが十分少なければ、
再結晶温度が高くても、深絞り性に好ましい再結晶集合
組織が得られる。Here, the present inventors have reached the following inference from several experimental facts. In other words, in order to obtain a recrystallized texture favorable for deep drawability, (i) the grain size of the hot-rolled sheet, that is, before cold rolling, must be sufficiently small; (11) the solid solution C and solid i8N during recrystallization must be sufficiently small; It is necessary to satisfy three conditions: (iii) the recrystallization temperature is sufficiently low; and (iii) the recrystallization temperature is low. However, (i
There is a complementary relationship between i) and (iii). In other words, if the recrystallization temperature is low enough, even if there is solute C and N, and conversely, if the solute C and N are sufficiently small,
Even if the recrystallization temperature is high, a recrystallization texture favorable for deep drawability can be obtained.

さて、製造コストを低減させるために、Ｔｉの添加量を
少なくしてゆくと、やがて、固溶Ｃが残存するようにな
る。またＴｉＯ量が減少すると析出物の量も減少し、再
結晶抑制効果が少なくなり、熱間圧延時の動的な再結晶
やその後の冷却の過程での粒成長が容易になり、熱間圧
延後の結晶粒径が大きくなる。また同時に、焼鈍時の再
結晶温度が低くなる。前記のごとく、固溶Ｃが存在する
状態で再結晶させても、再結晶温度が十分低ければ、深
絞り性に好ましい再結晶集合＆＋１織が発達する。Now, if the amount of Ti added is reduced in order to reduce manufacturing costs, solid solution C will eventually remain. In addition, when the amount of TiO decreases, the amount of precipitates also decreases, and the effect of suppressing recrystallization decreases, which facilitates dynamic recrystallization during hot rolling and grain growth during the subsequent cooling process. Later crystal grain size becomes larger. At the same time, the recrystallization temperature during annealing becomes low. As mentioned above, even if recrystallization is performed in the presence of solid solution C, if the recrystallization temperature is sufficiently low, a recrystallized aggregate &+1 weave, which is favorable for deep drawability, will develop.

ここに、本発明者らは、この固溶Ｃ量と再結晶温度の低
下のバランスを検討した結果、鋼中の全Ｃ量および全Ｎ
量が各々、ｏ、ｏｏｓｏ重量％以下、０゜００７００７
％以下の範囲ならば、ＴｉあるいはＺｒの添加量の減少
に伴う、炭窒化物の減少による再結晶温度の低下が、固
溶Ｃの増加に見あうことを明らかにし、かつ、熱間圧延
条件および巻取条件を適切に規制することにより、細か
な結晶粒が得られることを見い出した。これにより、安
価でかつ遅時効性で、肌荒れの恐れがなく、ｒ値の面内
異方性の少ない深絞り用冷延鋼板を連続焼鈍法によって
ででも製造できることが判明した。As a result of examining the balance between the amount of solid solute C and the decrease in recrystallization temperature, the inventors found that the total amount of C and total N in the steel
The amount is less than o, ooso weight%, respectively, 0゜007007
% or less, the decrease in the recrystallization temperature due to the decrease in carbonitrides associated with the decrease in the amount of Ti or Zr added is commensurate with the increase in solid solution C. It has also been found that fine crystal grains can be obtained by appropriately controlling the winding conditions. As a result, it has been found that a cold-rolled steel sheet for deep drawing that is inexpensive, has slow aging properties, is free from the risk of surface roughening, and has little in-plane anisotropy of the r value can be produced even by continuous annealing.

すなわち、本発明者らは、種々検討を続けたところ、Ｃ
固溶量が０．００１５％未満程度であれば「値、の面内
異方性も小さく、特に支障なく、その場合の結晶粒の粗
粒化も、熱間圧延時に低温大圧下を行うとともに熱間圧
延後も急冷、低温巻取りを行って粗粒化を抑制すること
により防止できることを見い出し、本発明を完成した。That is, the present inventors continued various studies and found that C.
If the amount of solid solution is less than 0.0015%, the in-plane anisotropy of ``value'' is small and there is no particular problem. It was discovered that coarsening can be prevented by performing rapid cooling and low-temperature winding even after hot rolling, and completed the present invention.

よって、ここに、本発明は、広義には、鋼中に０．００
１５重量％以下の固溶炭素が存在するようにＴｉおよび
Ｚｒを添加し、スキッド・マーク　（スラブ加熱時の温
度むら）が生じないように１１００”Ｃ以上で鋼片を均
熱した後、熱間圧延を７００〜８８０　℃で仕上げると
ともに、仕上げ温度と仕上げ温度＋１ｏ。Therefore, in a broad sense, the present invention provides 0.00 in steel.
Ti and Zr are added so that 15% by weight or less of solid solution carbon exists, and the steel slab is soaked at 1100"C or higher to prevent skid marks (temperature unevenness during heating of the slab). Finish rolling at 700 to 880°C, and increase the finishing temperature to +1o.

℃の間の温度域において、粗熱間圧延後の板厚の３０％
以上を圧下し、熱間圧延完了後５℃／Ｓ以上で急冷し、
３００〜５５０℃で巻取り、結晶粒径の小さな熱延板を
得、次いでこれを素材として用いて冷間圧延を行う、連
続焼鈍法によってでも、遅時効性で、絞り加工時に肌荒
れの恐れがなく、かつｒ値の面内異方性の小さな深絞り
用冷延鋼板の製造方法である。30% of the plate thickness after rough hot rolling in the temperature range between ℃
The above is rolled down, and after the hot rolling is completed, it is rapidly cooled at 5°C/S or more,
Even with continuous annealing, which involves winding at 300 to 550°C to obtain a hot-rolled sheet with a small grain size, and then cold-rolling it as a raw material, it has slow aging properties and there is no risk of roughening of the surface during drawing. This is a method for producing a cold-rolled steel sheet for deep drawing, which has no in-plane anisotropy of the r value.

さらに特定的には、本発明の要旨とするところは、重量
％で、 Ｃ：　０．０００５〜０．００５０％、Ｍｎ：　０．０
１〜０．５０％、Ｓ　：　０．０１％以下、　　　Ｎ　
：　０．０００５〜０．００７０，６、酸可溶性＃　０
．０２％以下、 かつ酸化物および硫化物として含まれるものを除き、３
．４　　Ｘ　Ｎ　＋４（Ｃ−０，００１５）　　≦Ｔ　
ｉ　＋　−Ｚ　ｒ＜３．４　ＸＮ＋４Ｃの範囲でＴｉお
よびＺｒの少なくとも一方を含み、 残部鉄および不可避不純物 よりなる組成を有する鋼を、１１００℃以上の温度に均
熱して仕上げ温度７００〜８８０′Ｃで熱間圧延を行い
、かつ仕上げ温度＋１００℃以下の温度域で、粗熱間圧
延後の板厚の３０％以上を圧下し、熱間圧延完了後５℃
／Ｓ以上で３００〜５５０℃まで急冷し、そのまま３０
０〜５５０℃で巻取り、次いで、圧下率７０〜９５％で
冷間圧延し、６８０〜８５０℃で連続焼鈍することを特
徴とする、遅時効性の深絞り用冷延鋼板の製造方法であ
る。More specifically, the gist of the present invention is that, in weight %, C: 0.0005-0.0050%, Mn: 0.0
1 to 0.50%, S: 0.01% or less, N
: 0.0005-0.0070.6, acid soluble #0
．． 0.2% or less, excluding those contained as oxides and sulfides,
．． 4 X N +4 (C-0,0015) ≦T
A steel containing at least one of Ti and Zr in the range of i + −Z r<3.4 Perform hot rolling at C, and reduce 30% or more of the plate thickness after rough hot rolling in a temperature range of finishing temperature + 100°C or less, and reduce the thickness by 5°C after completion of hot rolling.
/S or higher to 300-550℃, then leave it at 30℃.
A method for producing a slow-aging cold-rolled steel sheet for deep drawing, which is characterized by winding at 0 to 550°C, then cold rolling at a rolling reduction of 70 to 95%, and continuous annealing at 680 to 850°C. be.

なお、「粗熱間圧延」とは複数スタンドのタンデム熱間
圧延に先だち、鋼片を予め数十ミリ程度の厚さまで圧延
する熱間圧延を意味する。Note that "rough hot rolling" refers to hot rolling in which a steel billet is rolled in advance to a thickness of about several tens of millimeters prior to tandem hot rolling in multiple stands.

また、上記鋼片は一般に連続鋳造により製造されたスラ
ブ鋳片であるが、その他造塊法により分塊圧延を経た鋼
片であってもよく、特に制限はない。Further, the above-mentioned steel slab is generally a slab slab manufactured by continuous casting, but it may also be a steel slab that has been subjected to blooming and rolling using an ingot-forming method, and is not particularly limited.

（作用） 次に、本発明における鋼板の成分を前記のように限定し
ている理由について説明する。なお、本明細書において
「％」は特にことわりがない限り、「重量％」である。(Function) Next, the reason why the components of the steel plate in the present invention are limited as described above will be explained. In this specification, "%" means "% by weight" unless otherwise specified.

Ｃ： 鋼中に必然的に含有されるもので、０．０００５％未満
には、現在の製鋼技術では容易かつ安定してできない、
また、０．００５０％を超えると、ＴｉＣが多くなり再
結晶温度が過度に高くなってしまう。C: It is inevitably contained in steel and cannot be easily and stably reduced to less than 0.0005% using current steelmaking technology.
On the other hand, if it exceeds 0.0050%, the amount of TiC increases and the recrystallization temperature becomes excessively high.

好ましくは０．００１〜０．００３％である。Preferably it is 0.001 to 0.003%.

Ｍｎ＝ ＭｎはＳによる熱間脆性を防止するのにを効な元素であ
り、０．０１％以上含有させるのが好ましい。Mn= Mn is an element effective in preventing hot embrittlement caused by S, and is preferably contained in an amount of 0.01% or more.

しかし、０．５０％を超えると鋼が硬質化し延性が劣化
し、さらにｒ値も低下する。However, if it exceeds 0.50%, the steel becomes hard, the ductility deteriorates, and the r value also decreases.

Ｎ： Ｃと同様に鋼中に必然的に含有されるもので、ｏ、ｏｏ
ｏｓ％未溝には、現在の製鋼技術では容易かつ安定して
できない。また０、００７０％を超えると、添加するＴ
ｉおよびＺｒＯ量が増大し、製造コストが高くなる。好
ましくは０．００３０％以下におさえる。N: Like C, it is inevitably contained in steel, and o, oo
Os% ungrooved grooves cannot be easily and stably formed using current steelmaking technology. Also, if it exceeds 0.0070%, the added T
The amount of i and ZrO increases, and the manufacturing cost increases. Preferably it is kept below 0.0030%.

酸可溶Ａｌ： 溶鋼を真空脱ガスした後、ＴｉおよびＺｒを添加するの
に際し、ＴｉおよびＺｒの歩留りを向上させるため、予
め脱酸のために添加するもので、微量でも存在すれば脱
酸が充分行われていることを示している。しかし０．０
２％を超えて添加することは、メリットがなく単にコス
トの上昇を意味する。Acid-soluble Al: When adding Ti and Zr after vacuum degassing of molten steel, it is added in advance for deoxidation in order to improve the yield of Ti and Zr. It shows that this is being carried out adequately. But 0.0
Adding more than 2% has no merit and simply means an increase in cost.

Ｓ： ＳはＭｎよりＴｉと結合する傾向が強く、Ｓ含有量の増
加はＴｉの添加量の増大を招くので、０．０１％以下と
する。S: S has a stronger tendency to bond with Ti than Mn, and an increase in the S content leads to an increase in the amount of Ti added, so the content is set to 0.01% or less.

Ｔｉ５Ｚｒ： これらの元素は、同じような性質を示し、互いに置き換
えが可能なので、どちらか１種だけ添加しても、複合で
添加しても良い。しかし、酸化物、硫化物として鋼中に
含まれるものを除いて、３．４Ｎ　＋　４　（Ｃ−０，
００１５）≦Ｔｉ　＋−Ｚｒ＜３．４Ｎ＋４Ｃの範囲で
、添加されなければならない。なぜな％より少ないと、
鋼中に０．００１５％を超える固溶Ｃおよび固溶Ｎが存
在することになり、鋼板の遅時効性が確保できない。ま
た、（３，４Ｎ　＋４Ｃ）５以上になると、ＩＦ鋼にな
り、実質上すべてのＴｉ、Ｚｒが固定され、炭窒化物の
量が多くなり、それにともなって再結晶温度が高くなる
とともに、２次加工脆性も起こしやすくなる。Ti5Zr: These elements exhibit similar properties and can be replaced with each other, so either one of them may be added alone or in combination. However, excluding those contained in steel as oxides and sulfides, 3.4N + 4 (C-0,
0015) ≦Ti + - Zr must be added within the range of 3.4N+4C. Why less than %?
Since solid solution C and solid solution N exceed 0.0015% in the steel, the slow aging properties of the steel sheet cannot be ensured. Furthermore, when the temperature exceeds (3,4N +4C)5, it becomes an IF steel, in which virtually all Ti and Zr are fixed, the amount of carbonitrides increases, and the recrystallization temperature increases accordingly. Subsequent processing embrittlement is also likely to occur.

なお、Ｔｉ単独添加の場合、好ましくはＴｉ：０．０４
３８％以下、Ｚｒ単独添加のとき、好ましくは０．０８
３％以下である。In addition, in the case of adding Ti alone, preferably Ti: 0.04
38% or less, preferably 0.08 when Zr is added alone
It is 3% or less.

ここに、添付図面はＮ含有１０．００２０％のときに上
記関係式で示される領域、つまり本発明に係る組成領域
をグラフで示すものである。図中、斜線領域がそれであ
る。Here, the attached drawing is a graph showing the region shown by the above relational expression when the N content is 10.0020%, that is, the composition region according to the present invention. This is the shaded area in the figure.

なお、不純物としてのＰは通常の含存呈であれば害作用
を及ぼさないが、−Ｃには０．０２％以下に抑えるのが
好ましい。Note that P as an impurity does not have any harmful effect if it is present normally, but it is preferable to suppress -C to 0.02% or less.

本発明は、前述の通り、深絞り用冷延鋼板を製造するに
当り、前記鋼組成の鋼、例えば、連続鋳造スラブを１１
００℃以上に加熱し、仕上げ温度７００〜８８０℃で熱
間圧延を完了すると共に、この仕上げ温度と、仕上げ温
度＋１００℃との間の温度範囲で、粗熱間圧延後の板厚
の３０％以上を圧下し、更に、熱間圧延後、５℃／Ｓ以
上の冷却速度で３００〜５５０℃にまで急冷し、次いで
３００〜５５０℃の低温度で巻取ることを特徴としてい
る。これは、１１００℃未満で加熱すると、スラブに温
度むらが生じやすいためであり、また仕上げ温度を低く
し、かつ、低温域での圧下量を限定するのは、Ｔｉある
いはＺｒ含を量が少なくなって、熱間圧延中の動的再結
晶抑制効果が弱まったのを補うためで、これをはずれる
と熱間圧延後の結晶粒径が大きくなり。ｒ値の面内異方
性が大きくなる。更に、熱間圧延後の冷却速度を限定し
、巻取温度を低くしたのは、熱延後の冷却中の粒成長を
抑制するためである。このようなプロセスにより結晶粒
の細かな熱延板が得られる。As mentioned above, in producing a cold-rolled steel sheet for deep drawing, the present invention uses a steel having the above-mentioned steel composition, for example, a continuous casting slab.
Heating to 00℃ or higher and completing hot rolling at a finishing temperature of 700 to 880℃, and in a temperature range between this finishing temperature and finishing temperature + 100℃, 30% of the plate thickness after rough hot rolling. The above is rolled down, and after hot rolling, it is rapidly cooled to 300 to 550°C at a cooling rate of 5°C/S or more, and then coiled at a low temperature of 300 to 550°C. This is because heating below 1100°C tends to cause temperature unevenness in the slab, and lowering the finishing temperature and limiting the amount of reduction in the low temperature range is because the amount of Ti or Zr is small. This is to compensate for the weakening of the dynamic recrystallization suppressing effect during hot rolling, and if this is removed, the grain size after hot rolling will increase. The in-plane anisotropy of the r value increases. Furthermore, the reason why the cooling rate after hot rolling is limited and the winding temperature is lowered is to suppress grain growth during cooling after hot rolling. A hot-rolled sheet with fine grains can be obtained by such a process.

本発明では、巻取後さらに脱スケールし冷間圧延するが
冷間圧延するに当たって、圧下率は７０〜９５％とする
。これはこの範囲を外れると焼鈍時にｒ値改善に好まし
い再結晶集合Ｍｉ織が発達しないためである。In the present invention, after winding, the material is further descaled and cold rolled, and the reduction ratio is set to 70 to 95% during cold rolling. This is because, outside this range, the recrystallized Mi texture, which is preferable for improving the r value, will not develop during annealing.

次に、かかる冷延材について６８０〜８５０℃で焼鈍す
るが、これは６８０℃未満では再結晶が完了するのに時
間がかかりすぎ、十分粒成長しないためであり、一方、
８５０℃を超えると、ヒートバックリングや、ハースロ
ールによるすり傷等の発生頻度が著しく高くなるからで
ある。Next, the cold-rolled material is annealed at 680 to 850°C, because below 680°C it takes too long to complete recrystallization and grains do not grow sufficiently;
This is because when the temperature exceeds 850°C, the frequency of occurrence of heat buckling, scratches due to hearth rolls, etc. increases significantly.

鋼板は焼鈍後調質圧延されてから、製品として出荷され
る。Steel plates are annealed and temper rolled before being shipped as products.

次に本発明の実施例を示すが、これは単に本発明の例示
であって、これにより本発明が不当に制限されるもので
はない。Next, examples of the present invention will be shown, but these are merely illustrative of the present invention and are not intended to unduly limit the present invention.

実施例 第１表に示す組成を有する鋼を、実験用真空溶解炉で溶
製した。これを３分割し、熱間加工により２０ＩＩＩＩ
１１厚のスラブとした。これを１２００℃に１時間加熱
後、仕上げ温度が７００〜８８０℃に入るように５パス
で４１厚に圧延した。ただし、最終２パスは、狙いの仕
上げ温度＋１００℃より冷えてから圧延し、各々の圧下
率をもとのスラブ厚の２０％、１５％とした。この熱間
圧延後ただちに水スプレー冷却により急冷しく連続鋳造
速度はぼ２〜ｂに相当）、種々の温度に保持した炉の中
に挿入し、３０分保持後、２０℃／ｈｒで冷却して巻取
のシュミレーションとした。Example Steel having the composition shown in Table 1 was melted in an experimental vacuum melting furnace. This was divided into three parts and heated to 20III.
It was made into a slab with a thickness of 11. After heating this to 1200°C for 1 hour, it was rolled to a thickness of 41 in 5 passes so that the finishing temperature was between 700 and 880°C. However, in the final two passes, the slab was rolled after it had cooled down from the target finishing temperature +100°C, and the respective rolling reductions were 20% and 15% of the original slab thickness. Immediately after this hot rolling, it was quenched by water spray cooling (continuous casting speed corresponds to approximately 2-b), inserted into a furnace maintained at various temperatures, held for 30 minutes, and then cooled at 20°C/hr. This is a simulation of winding.

このようにして得た巻取材同等材を脱スケール後、０．
８ｍｍまで圧下率７８％で冷間圧延し、次いで加熱速度
１０℃／Ｓで；　７８０℃で１分間均熱してから冷却速
度１０℃／Ｓで連続焼鈍し、伸び率１．２％で調質圧延
を行った。After descaling the material equivalent to the rolled material obtained in this way, 0.
Cold rolled to 8 mm at a reduction rate of 78%, then heated at a heating rate of 10°C/S; Soaked at 780°C for 1 minute, then continuously annealed at a cooling rate of 10°C/S, and tempered at an elongation rate of 1.2%. Rolling was performed.

かかる供試材からＪＩＳ　５号引張試験片を作り、殿械
的性質および焼付硬化１（１１１１）を測定した。結果
を同じく第１表にまとめて示す。同表によれば比較例で
ある１ｋｌｏは、Ｃが多くかつｒｉ、、’ｚｒの添加量
が少ないため、固溶Ｃ呈が多（Ｂ１１が大きいし、降伏
点も高い。同じく比較例である阻１１〜１４は、熱間圧
延、巻取条件が不適切なため圧延方向に対し４５°方向
のｒ値が悪く、平均ｒ値もまた面内異方性も悪い。A JIS No. 5 tensile test piece was prepared from the sample material, and the mechanical properties and bake hardening 1 (1111) were measured. The results are also summarized in Table 1. According to the same table, 1klo, which is a comparative example, has a large amount of C and a small amount of ri, , 'zr added, so it has a large amount of solid solution C (B11 is large and the yield point is high. Samples Nos. 11 to 14 had poor r values in the 45° direction with respect to the rolling direction because the hot rolling and winding conditions were inappropriate, and the average r values and in-plane anisotropy were also poor.

なお、第１表中、「＊」印は本発明の範囲外であること
を示す。In addition, in Table 1, the mark "*" indicates that it is outside the scope of the present invention.

（発明の効果） 以上詳述したように、本発明によれば、熱延板の結晶粒
径を十分小さくでき、固溶Ｃ量を０．００１５％未満に
まで許容できるため、Ｔｉ添加量を極力少なくできると
ともに、耐常温歪時効性および耐２次加工脆性のみられ
ない、かつｒ値面異方性の小さい安価な深絞り用冷延鋼
板が製造できるのである。(Effects of the Invention) As detailed above, according to the present invention, the grain size of the hot rolled sheet can be sufficiently reduced and the amount of solid solution C can be tolerated to less than 0.0015%, so the amount of Ti added can be reduced. This makes it possible to produce an inexpensive cold-rolled steel sheet for deep drawing that has as little amount as possible, exhibits no room-temperature strain aging resistance, no secondary work embrittlement resistance, and has low r-value plane anisotropy.

【図面の簡単な説明】[Brief explanation of drawings]

添付図面第１図は、酸化物、硫化物として含まれるもの
は除き、鋼中Ｎ含有量を０．００２０％としたときの 本発明の範囲内の（’ｒｉ＋　　　　Ｚｒ）ｆｆｉおよ
び（Ｊ７の許容範囲を示すグラフである。Figure 1 of the attached drawings shows the allowable ('ri+Zr)ffi and (J7) within the scope of the present invention when the N content in the steel is 0.0020%, excluding those contained as oxides and sulfides. It is a graph showing a range.

Claims (1)

【特許請求の範囲】 重量％で、 Ｃ：０．０００５〜０．００５０％、Ｍｎ：０．０１〜
０．５０％、Ｓ：０．０１％以下、Ｎ：０．０００５〜
０．００７０％、酸可溶性Ａｌ：０．０２％以下、 かつ酸化物および硫化物として含まれるものを除き、３
．４×Ｎ＋４（Ｃ−０．００１５）≦Ｔｉ＋（４８／９
３）Ｚｒ＜３．４×Ｎ＋４Ｃの範囲でＴｉおよびＺｒの
少なくとも一種を含み、 残部鉄および不可避不純物 よりなる組成を有する鋼を、１１００℃以上の温度に均
熱して仕上げ温度７００〜８８０℃で熱間圧延を行い、
かつ仕上げ温度＋１００℃以下の温度域で、粗熱間圧延
後の板厚の３０％以上を圧下し、熱間圧延完了後５℃／
Ｓ以上で３００〜５５０℃まで急冷し、そのまま３００
〜５５０℃で巻取り、次いで、圧下率７０〜９５％で冷
間圧延し、６８０〜８５０℃で連続焼鈍することを特徴
とする、遅時効性の深絞り用冷延鋼板の製造方法。[Claims] In weight%, C: 0.0005-0.0050%, Mn: 0.01-0.01%
0.50%, S: 0.01% or less, N: 0.0005~
0.0070%, acid-soluble Al: 0.02% or less, and excluding those contained as oxides and sulfides, 3
．． 4×N+4(C-0.0015)≦Ti+(48/9
3) Steel having a composition containing at least one of Ti and Zr in the range of Zr<3.4×N+4C, and the balance consisting of iron and unavoidable impurities is soaked at a temperature of 1100°C or higher and finished at a finishing temperature of 700 to 880°C. Perform hot rolling,
And in a temperature range of finishing temperature + 100℃ or less, reduce 30% or more of the plate thickness after rough hot rolling, and reduce the temperature by 5℃/after completion of hot rolling.
Rapidly cool down to 300-550℃ at temperature S or higher, then heat to 300℃
A method for producing a slow-aging cold-rolled steel sheet for deep drawing, which comprises winding at ~550°C, then cold rolling at a rolling reduction of 70-95%, and continuous annealing at 680-850°C.