JPH0762180B2 - Method for producing cold-rolled steel sheet with excellent deep patterning property and aging characteristics by continuous annealing - Google Patents
Method for producing cold-rolled steel sheet with excellent deep patterning property and aging characteristics by continuous annealingInfo
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- JPH0762180B2 JPH0762180B2 JP10063490A JP10063490A JPH0762180B2 JP H0762180 B2 JPH0762180 B2 JP H0762180B2 JP 10063490 A JP10063490 A JP 10063490A JP 10063490 A JP10063490 A JP 10063490A JP H0762180 B2 JPH0762180 B2 JP H0762180B2
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Description
【発明の詳細な説明】 （産業上の利用分野） 本発明はAlキルド鋼冷延鋼板の製造方法に関するもので
あり、加熱された鋳片を特定の温度域で圧延を行い冷延
後特定の熱履歴を持つ連続焼鈍を行うことによって深絞
り性および時効特性の優れた冷延鋼板を製造する方法を
提供するものである。Description: TECHNICAL FIELD The present invention relates to a method for producing an Al-killed steel cold-rolled steel sheet, in which a heated slab is rolled in a specific temperature range and then cooled to a specific temperature. It is intended to provide a method for producing a cold-rolled steel sheet excellent in deep drawability and aging characteristics by performing continuous annealing having a heat history.
（従来の技術） 深絞り用冷延鋼板の素材としてAlキルド鋼を用い、連続
焼鈍で製造する場合、箱焼鈍で製造する方法と同等の加
工性と時効特性にすることは困難であった。(Prior Art) When using Al-killed steel as a material for a deep-drawing cold-rolled steel sheet and performing continuous annealing, it was difficult to obtain workability and aging characteristics equivalent to those of the method of producing by box annealing.
この解決方法として、例えば特開昭58−48635号公報に
開示されるように鋼中のC,Mn,P量に応じて表される特定
の温度から仕上げ圧延を行い、急冷するという方法があ
るが、深絞り性と時効特性に大きな影響をおよぼす鋼中
のMnSの制御が充分でないため深絞り性、時効特性のい
ずれも充分なものとはならず、巻取温度によっては冷延
鋼板の肌荒れが発生する可能性もある。また、鋼中の析
出物の制御を行い加工性と時効性を向上させるためには
特開昭58−31034号公報に開示されているように冷片ス
ラブを1020〜1180℃まで加熱した後、熱延を行いその後
冷延、焼鈍を行う方法がある。この方法では特にスラブ
を1020〜1100℃に加熱した場合、スラブを1100℃以上に
加熱した場合には発生しなかった熱延板の粗大粒が発生
しやすいため、冷延鋼板の肌荒れがおこりやすくなる。
また、コイル全長にわたって仕上げ温度をAr3点以上に
確保することが難しくなる。肌荒れの問題を避けるため
には、例えば特開昭58−31033号公報に開示されている
ように熱延後630℃以下で巻き取る方法があるが、深絞
り性の充分なものが製造できないことおよび仕上げ温度
の確保が困難になること等の問題が残る。As a solution to this, for example, as disclosed in JP-A-58-48635, there is a method of performing finish rolling from a specific temperature represented according to the amounts of C, Mn, and P in steel and quenching. However, since the control of MnS in steel, which has a large effect on the deep drawability and aging characteristics, is not sufficient, neither the deep drawability nor the aging characteristics are sufficient, and the surface roughness of the cold rolled steel sheet may become rough depending on the winding temperature. May occur. Further, in order to control the precipitates in the steel and improve the workability and the aging property, after heating the cold piece slab to 1020 to 1180 ° C. as disclosed in JP-A-58-31034, There is a method of hot rolling and then cold rolling and annealing. In this method, especially when the slab is heated to 1020 to 1100 ° C, coarse grains of the hot rolled sheet that do not occur when the slab is heated to 1100 ° C or more are likely to occur, so that the rough surface of the cold rolled steel sheet easily occurs. Become.
Further, it becomes difficult to secure the finishing temperature at the Ar 3 point or higher over the entire length of the coil. In order to avoid the problem of rough skin, for example, as disclosed in JP-A-58-31033, there is a method of winding at 630 ° C. or lower after hot rolling, but it is impossible to produce a product with sufficient deep drawability. Also, there remain problems such as difficulty in securing the finishing temperature.
（発明が解決しようとする課題） そこで、本発明では低炭素Alキルド鋼を使用し、スラブ
を1100℃以上に加熱した場合の仕上げ温度のAr3点以上
の確保が容易であることと、肌荒れが防止できるという
利点を保持しつつ、従来技術では困難であった深絞り性
および時効特性に優れた冷延鋼板を製造することを目的
とするものである。(Problems to be solved by the invention) Therefore, in the present invention, low carbon Al killed steel is used, and it is easy to secure Ar 3 points or more of the finishing temperature when the slab is heated to 1100 ° C or more, and rough skin. It is an object of the present invention to produce a cold-rolled steel sheet excellent in deep drawability and aging characteristics, which has been difficult with the prior art while maintaining the advantage that
（課題を解決するための手段） 本発明者らは鋳片を1100℃以上に加熱した後、Mn量、Ｓ
量に応じた特定温度域で圧下率50％以上の圧延を行い、
かつ急速冷却と再加熱過時効を含む連続焼鈍を行うこと
によって上記目的が達成できることを見出した。(Means for Solving the Problems) The inventors of the present invention heated the cast slab to 1100 ° C. or higher, and then added Mn and S
Rolling with a reduction rate of 50% or more in a specific temperature range according to the amount,
It was also found that the above object can be achieved by performing continuous annealing including rapid cooling and reheating overaging.
本発明の要旨とするところは、重量比にてC:0.010〜0.0
38％,Si:0.04％以下,Mn:0.05〜0.25％,S:0.003〜0.020
％,Al:0.010〜0.10％,N:0.0060％以下を含有し、残部が
Feおよび不可避的不純物よりなる鋳片を1100℃以上に加
熱し熱延を行い、鋳片の表面温度が下記式に示すT1の温
度域の範囲内において鋳片の表面温度がT1の温度域の上
限に達したときの板厚に対して圧下率50％以上の圧延を
加え、900℃以上温度で熱延を終了し、600℃以上800℃
以下の温度で巻き取った後、冷延し、700℃以上900℃以
下の温度で焼鈍し、この温度域から690〜650℃の温度範
囲に３〜20℃／秒で冷却し、続いて200〜340℃の温度範
囲に50〜200℃／秒で冷却し、さらに345〜450℃の温度
範囲に加熱し、この温度範囲から200〜330℃の温度範囲
に100秒以上の時間をかけて徐冷することを特徴とする
連続焼鈍による深絞り性および時効特性の優れた冷延鋼
板の製造方法にある。Where the gist of the present invention is, C: 0.010 to 0.0 by weight ratio.
38%, Si: 0.04% or less, Mn: 0.05 to 0.25%, S: 0.003 to 0.020
%, Al: 0.010 to 0.10%, N: 0.0060% or less, the balance is
The slab consisting of Fe and unavoidable impurities is heated to 1100 ° C or higher and hot-rolled, and the surface temperature of the slab is within the temperature range of T1 shown in the following formula. Rolling with a reduction of 50% or more to the plate thickness when the upper limit is reached, hot rolling is completed at a temperature of 900 ° C or higher, and 600 ° C or higher to 800 ° C
After winding at the following temperature, it is cold-rolled, annealed at a temperature of 700 ° C or more and 900 ° C or less, cooled from this temperature range to a temperature range of 690 to 650 ° C at 3 to 20 ° C / sec, and then 200 To 340 ° C at a rate of 50-200 ° C / sec, further heat to a temperature range of 345-450 ° C, and gradually change from this temperature range to 200-330 ° C over 100 seconds. A method for producing a cold-rolled steel sheet having excellent deep drawability and aging characteristics by continuous annealing, which is characterized by cooling.
（但し、T1の下限は900℃とする） 以下、本発明を詳細に説明する。 (However, the lower limit of T1 is 900 ° C.) Hereinafter, the present invention will be described in detail.
まず、本発明の方法を適用する鋼の化学成分の限定理由
について説明する。First, the reasons for limiting the chemical composition of steel to which the method of the present invention is applied will be described.
Ｃは0.010％未満では連続焼鈍後の時効劣化が大きいの
で望ましくない。また0.038％を越えると製品の深絞り
性が劣化する。したがって、Ｃ量を0.010〜0.038％に限
定した。When C is less than 0.010%, aging deterioration after continuous annealing is large, which is not desirable. If it exceeds 0.038%, the deep drawability of the product will deteriorate. Therefore, the amount of C is limited to 0.010 to 0.038%.
Siは微量では問題は無いが、含有量が多くなると加工性
を低下させる。したがって、0.04％以下でなければなら
ない。Although there is no problem with a small amount of Si, if the content of Si increases, the workability decreases. Therefore, it must be 0.04% or less.
Mnは熱間脆性を防止するために必要な成分であるが、0.
05％未満ではFeSが生成し、その効果を奏しない。ま
た、0.25％を越えると深絞り性が劣化する。したがっ
て、Mn量を0.05〜0.25％に限定した。Mn is a component necessary to prevent hot brittleness, but 0.
If it is less than 05%, FeS is generated and its effect is not exerted. Further, if it exceeds 0.25%, the deep drawability deteriorates. Therefore, the amount of Mn was limited to 0.05 to 0.25%.
Ｓは0.003％未満ではMnSの生成量が少なく、熱延板の結
晶粒が粗粒化しやすく肌荒れの原因となる。また0.020
％を越えると熱間脆性の原因となる。したがって、Ｓ量
を0.003〜0.020％に限定した。If S is less than 0.003%, the amount of MnS produced is small, and the crystal grains of the hot-rolled sheet are likely to become coarse, which causes rough skin. Also 0.020
When it exceeds%, it causes hot brittleness. Therefore, the S amount is limited to 0.003 to 0.020%.
Alは鋼中の酸素，窒素量をコントロールするのに必要な
元素であり、熱延板の巻き取り後にＮをAlNとして析出
させるためには最低0.010％は必要である。しかし、0.1
0％を越えると加工性を劣化させる。したがって、Al量
を0.010〜0.10％に限定した。特に、析出するAlNのサイ
ズを肌荒れが起きない程度に粗大化させ、加工性を向上
させるためには0.030〜0.080％の範囲が望ましい。Al is an element necessary for controlling the amounts of oxygen and nitrogen in steel, and at least 0.010% is necessary for precipitating N as AlN after winding the hot-rolled sheet. But 0.1
If it exceeds 0%, workability is deteriorated. Therefore, the amount of Al is limited to 0.010 to 0.10%. In particular, the range of 0.030 to 0.080% is desirable in order to coarsen the size of precipitated AlN to the extent that rough skin does not occur and to improve workability.
また、析出したAlNも加工性を劣化させるためその量は
少ない方が良く、そのためにＮ量は0.0060％以下でなけ
ればならない。In addition, the precipitated AlN also deteriorates the workability, so the amount is preferably small, and therefore the amount of N must be 0.0060% or less.
次に、熱間圧延条件について説明する。Next, the hot rolling conditions will be described.
深絞り性および時効特性を良好にするためには鋼中のMn
Sの析出状態を制御する必要があるが、本発明ではこの
制御を熱延中に行うことが特徴である。そのためには加
熱されたスラブをMn量とＳ量によって表されるT1の温度
範囲内において鋳片の表面温度がT1の温度域に上限に達
したときの板厚に対して圧下率50％以上の圧延を加える
ことが必要であることを多くの実験により知見した。In order to improve the deep drawability and aging characteristics, Mn in steel is
Although it is necessary to control the precipitation state of S, the feature of the present invention is that this control is performed during hot rolling. To do this, the heated slab has a rolling reduction of 50% or more with respect to the plate thickness when the surface temperature of the slab reaches the upper limit of the temperature range of T1 within the temperature range of T1 represented by the amounts of Mn and S. It was found by many experiments that it was necessary to add the rolling of.
第２表は第１表に示す鋼A,B,C,D,E,Fのスラブを1250℃
に加熱した後、種々の温度から圧延を開始し、種々の圧
下率の圧延を加え、900℃以上で圧延を終了し、さらに
この熱延板を720℃で巻き取り、75％の冷延と第１図に
示すヒートパターンの連続焼鈍を施した場合の圧延条件
および冷延鋼板の値、時効指数を示す。Table 2 shows the slabs of steel A, B, C, D, E and F shown in Table 1 at 1250 ℃.
After heating to various temperatures, start rolling from various temperatures, add rolling with various reduction ratios, finish rolling at 900 ° C or higher, and further wind this hot-rolled sheet at 720 ° C and cool it to 75%. The rolling conditions, the values of the cold-rolled steel sheet, and the aging index when continuous annealing of the heat pattern shown in FIG. 1 is performed are shown.
第２図は第１表の鋼Ｂのスラブを1300℃に加熱し、1150
℃より圧延を開始し、1070℃までの間に種々の圧下率に
より熱延板とした後、720℃で巻き取り、続いて80％の
冷延と第１図に示すヒートパターンの連続焼鈍を行った
とき上記熱延圧下率の値および時効指数におよぼす影
響を示したものである。Figure 2 shows that the slab of steel B in Table 1 was heated to 1300 ° C
Rolling was started at ℃, and hot rolled sheets were rolled up to 1070 ℃ with various reduction ratios, then rolled at 720 ℃, followed by 80% cold rolling and continuous annealing of the heat pattern shown in Fig. 1. It shows the effect on the value of the hot rolling reduction and the aging index when it is carried out.
第１表、第２表および第２図よりわかるように良好な深
絞り性および時効特性を得るためにはMn量およびＳ量に
応じて決まる温度T1の温度範囲内において少なくとも50
％以上の圧下率の圧延が必要であることが明白である。
なお、温度T1および圧延の圧下率はMnSの析出に深く係
わっていることがわかり、本発明の条件にしたがって圧
延を行った場合の熱延板のMnSを電子顕微鏡により調査
したところ、本発明の条件にしたがって製造された場
合、0.05〜0.2μｍのMnSが均一に分散した状態となって
おり、0.05μｍ未満の微細なMnSは生成していないこと
がわかった。これに対し、圧延の温度域、圧延量のいず
れか一方または両方が本発明の条件からはずれたものは
0.05〜0.2μｍのMnSは非常に少なくなっており、0.05μ
ｍ未満の微細なMnSが多数析出していることがわかっ
た。これまでの試験により0.05μｍ未満の多数のMnSは
粒成長性を阻害するため連続焼鈍において深絞り性を高
めるための（111）面の結晶粒の成長を遅らせ値を低
くすることがわかっている。さらに冷延鋼板の析出物を
電子顕微鏡により調査したところ0.05〜0.2μｍのMnSの
大部分はセメンタイトの析出核になっていることおよび
0.05μｍ未満のMnSの大部分はセメンタイトの析出核に
なっていないことがわかり、本発明の範囲で製造した場
合は時効特性が良好になり、本発明の範囲から外れた場
合は時効特性が劣化することの裏付けも得られている。 As can be seen from Table 1, Table 2 and FIG. 2, in order to obtain good deep drawability and aging characteristics, at least 50 within the temperature range of temperature T1 determined by the amount of Mn and the amount of S.
It is clear that rolling with a rolling reduction of not less than% is necessary.
It is understood that the temperature T1 and the rolling reduction are deeply related to the precipitation of MnS, and MnS of the hot-rolled sheet in the case of rolling according to the conditions of the present invention was investigated by an electron microscope. It was found that when manufactured according to the conditions, MnS of 0.05 to 0.2 μm was uniformly dispersed, and fine MnS of less than 0.05 μm was not formed. On the other hand, if one or both of the rolling temperature range and rolling amount deviates from the conditions of the present invention,
MnS of 0.05-0.2μm is very low, 0.05μm
It was found that a large number of fine MnS of less than m were precipitated. It has been known from previous tests that a large number of MnS of less than 0.05 μm retard the growth of crystal grains on the (111) plane to enhance deep drawability in continuous annealing because they inhibit grain growth. . Furthermore, when the precipitates of the cold-rolled steel sheet were examined by an electron microscope, most of the MnS of 0.05 to 0.2 μm became precipitation nuclei of cementite, and
It was found that most of MnS below 0.05 μm did not become precipitation nuclei of cementite, and when manufactured in the range of the present invention, the aging property was good, and when it was out of the range of the present invention, the aging property was deteriorated. The proof of doing is obtained.
以上のようにMn量およびＳ量に応じて決まる温度T1の温
度範囲において少なくとも50％以上の圧下率の圧延を行
うことによって0.05μｍ未満の深絞り性に害を与えるMn
Sの生成を防止でき、かつ時効特性を良好にする0.05μ
ｍ以上のMnSの生成を助長できるため深絞り性および時
効特性が良好になることが本発明の特徴である。As described above, by rolling at a rolling reduction of at least 50% or more in the temperature range of temperature T1 determined according to the amount of Mn and the amount of S, Mn of less than 0.05 μm is impaired in deep drawability.
0.05μ that can prevent the generation of S and improve the aging characteristics
It is a feature of the present invention that deep drawability and aging characteristics are improved because the production of MnS of m or more can be promoted.
なお、上記調査において組成、熱延温度範囲、巻取温
度、連続焼鈍の焼鈍温度、冷却速度および過時効処理条
件を本発明の範囲内で変更したもの、あるいはT1の温度
範囲内で圧下率50％以上の圧延を行うことを前提とし90
0℃以上でかつT1を温度範囲外でさらに圧延を行った場
合でも良好な深絞り性および時効特性が得られることが
わかった。In the above investigation, composition, hot rolling temperature range, coiling temperature, annealing temperature of continuous annealing, cooling rate and overaging treatment conditions changed within the scope of the present invention, or a reduction rate of 50 within the temperature range of T1. 90% or more of rolling
It was found that good deep drawability and aging characteristics are obtained even when rolling is performed at 0 ° C or higher and T1 is out of the temperature range.
巻取温度はAlNの析出を充分に行わせるためには600℃以
上が必要であるが、800℃を越えると熱延板の結晶粒が
粗大化し、連続焼鈍板の肌荒れが起こりやすくなる。し
たがって、AlNを析出させ、かつ熱延板の結晶粒の粗大
化を防止し、さらに熱延板中のセメンタイト凝集を図り
加工性を向上させるためには、下限が600℃で上限が800
℃でなければならない。第３図は第１表に示す鋼Ｂのス
ラブを1200℃に加熱し、1150〜1080℃間において1150℃
になった時点での板厚に対して70％の圧下率で圧延を行
い、さらに1050〜920℃間において1050℃になった時点
での板厚に対して50％の圧下率で圧延を行い、920℃で
圧延を終了し、550〜850℃で巻き取り、続いて80％の冷
延を行い、第１図に示すヒートパターンの連続焼鈍を行
ったとき、上記巻取温度の値、時効指数におよぼす影
響を示したものである。The coiling temperature needs to be 600 ° C. or higher in order to sufficiently precipitate AlN, but if it exceeds 800 ° C., the crystal grains of the hot rolled sheet become coarse and the rough surface of the continuous annealed sheet is likely to occur. Therefore, in order to precipitate AlN and prevent the coarsening of the crystal grains of the hot-rolled sheet and further improve the workability by cementite aggregation in the hot-rolled sheet, the lower limit is 600 ° C and the upper limit is 800 ° C.
Must be ° C. Fig. 3 shows the steel B slabs shown in Table 1 heated to 1200 ° C, and the temperature between 1150 and 1080 ° C is 1150 ° C.
Rolling at a reduction rate of 70% of the sheet thickness at the time of becoming 1050 ° C, and rolling at a reduction rate of 50% of the sheet thickness at the time of reaching 1050 ° C between 1050 and 920 ° C. After rolling at 920 ° C, winding at 550 to 850 ° C, followed by 80% cold rolling and continuous annealing of the heat pattern shown in Fig. 1, the value of the above winding temperature and aging This shows the effect on the index.
冷間圧延の圧下率は通常行われている程度で良いが、連
続焼鈍後の（111）集合組織を発達させ、深絞り性を良
好にするためには70％以上の高圧下冷延率が好ましい。The reduction ratio of cold rolling may be the usual one, but in order to develop the (111) texture after continuous annealing and to improve the deep drawability, a cold rolling reduction under high pressure of 70% or more is required. preferable.
次に連続焼鈍条件について説明する。加熱温度は再結晶
温度以上が必要であるが、充分な加工性をもたせるため
には700℃以上で焼鈍する必要がある。しかし、900℃を
越える温度で焼鈍を行うとγ相となるため集合組織がラ
ンダム化し、深絞り性が著しく劣化する。したがって、
700〜900℃での焼鈍が必要である。省エネルギーや冷延
鋼板の表面キズの防止のためには700〜830℃での焼鈍が
望ましい。なお、より材質を均質にし、かつ表面性状の
良好な冷延鋼板とするためには焼鈍温度に応じて焼鈍時
間を変化させることが好ましく、例えば700℃の焼鈍の
場合は60秒程度が良く、900℃の焼鈍の場合は20秒程度
が良い。この再結晶焼鈍後、３〜20℃／秒で690〜650℃
への冷却を行うことによってさらに深絞り性が良好にな
り、かつ時効特性も良好な冷延鋼板が製造できる。この
冷却速度が３℃／秒より遅い場合は肌荒れが起こりやす
く、20℃／秒より速い場合はこの処理による深絞り性、
時効特性の向上効果がなくなる。また３〜20℃／秒で冷
却を行った場合でも650℃よりも低温に冷却すると時効
特性が劣化し、690℃よりも高温で冷却を止めると深絞
り性、時効特性の向上効果がなくなる。Next, the continuous annealing conditions will be described. The heating temperature needs to be higher than the recrystallization temperature, but in order to have sufficient workability, it is necessary to anneal at 700 ° C or higher. However, if annealing is performed at a temperature exceeding 900 ° C., a γ phase is formed, so that the texture is randomized and the deep drawability is significantly deteriorated. Therefore,
Annealing at 700-900 ° C is required. Annealing at 700 to 830 ° C is desirable in order to save energy and prevent surface scratches on the cold-rolled steel sheet. In addition, it is preferable to change the annealing time according to the annealing temperature in order to make the material more homogeneous and to have a good surface quality cold rolled steel sheet. For example, in the case of annealing at 700 ° C., about 60 seconds is good, In the case of 900 ° C annealing, about 20 seconds is good. After this recrystallization annealing, 690-650 ℃ at 3-20 ℃ / sec
By further cooling the steel sheet, the deep drawability is further improved, and a cold rolled steel sheet with good aging characteristics can be manufactured. If this cooling rate is slower than 3 ° C / sec, rough skin is likely to occur, and if it is faster than 20 ° C / sec, deep drawability by this treatment,
The effect of improving aging characteristics is lost. Even when cooling is performed at 3 to 20 ° C./sec, aging characteristics deteriorate when cooled to a temperature lower than 650 ° C., and when the cooling is stopped at a temperature higher than 690 ° C., the effect of improving deep drawability and aging characteristics disappears.
その後50〜200℃／秒で急速冷却を行うことが時効特性
を良好にするためには欠かせない条件である。この冷却
速度は50℃／秒よりも遅くなると結晶粒内のFe3C数が充
分に生成しないため時効特性が劣化する。また200℃／
秒よりも速いと結晶粒内のFe3C数が必要以上に多数生成
し加工性が劣化することおよび冷却終了の温度で冷却制
御が困難になるため、これ以下の冷却速度でなければな
らない。冷却終了温度は良好な加工性と時効特性を兼ね
備えた冷延鋼板を製造するためには重要である。すなわ
ち、冷却終了温度が340℃を越えると結晶粒内のFe3C数
が少なくなるため時効特性が劣化する。また、冷却終了
温度が200℃より低温になると結晶粒内のFe3C数が必要
以上に多数生成するため時効特性は良好になるものの、
降伏強度の上昇や伸びの劣化等が起こり充分な加工性が
得られない。冷却終了温度が200〜340℃であれば時効特
性および加工性共に充分良好なものが得られる。この冷
却後に345〜450℃に再加熱処理を行うのが本発明の特徴
の一つである。この再加熱はＣの拡散速度を速くし、急
速冷却終了時点でMnSの周囲に析出を開始したFe3Cの成
長を迅速に行わせるためのものであるが、345℃に満た
ない温度に加熱した場合はＣの拡散速度が遅いためにこ
の効果が少なく、450℃を超える温度に加熱するとMnS周
囲に析出しているFe3Cが鋼中へ再固溶を始めるためFe3C
数が減少し、いずれの場合も時効特性が良好なものがで
きない。再加熱後、200〜330℃の温度範囲に100秒以上
の時間をかけて徐冷却することによりＣの析出をより促
進させる効果が最も大きく発揮できる。330℃を超える
温度あるいは200℃に満たない温度へ徐冷した場合はＣ
のFe3Cとしての析出が遅れるために時効特性の良好な鋼
板が製造できない。また、この徐冷に要する時間が100
秒に満たない場合でもＣが充分に析出しないため時効特
性の良好な鋼板が製造できない。Then, rapid cooling at 50 to 200 ° C / sec is an essential condition for improving the aging characteristics. If this cooling rate becomes slower than 50 ° C / sec, the Fe 3 C number in the crystal grains will not be sufficiently generated and the aging characteristics will deteriorate. 200 ° C /
If it is faster than 2 seconds, the number of Fe 3 C in the crystal grains becomes excessively large and the workability deteriorates, and cooling control becomes difficult at the temperature at the end of cooling, so the cooling rate must be lower than this. The cooling end temperature is important for producing a cold rolled steel sheet having both good workability and aging characteristics. That is, when the cooling end temperature exceeds 340 ° C., the number of Fe 3 C in the crystal grains decreases and the aging characteristics deteriorate. Further, when the cooling end temperature is lower than 200 ° C., the number of Fe 3 C in crystal grains is increased more than necessary, so that the aging property is improved,
Sufficient workability cannot be obtained due to increase of yield strength and deterioration of elongation. When the cooling end temperature is 200 to 340 ° C, sufficiently good aging characteristics and workability can be obtained. One of the features of the present invention is to perform reheating treatment at 345 to 450 ° C after the cooling. This reheating is to accelerate the diffusion rate of C and to rapidly grow Fe 3 C which has started to precipitate around MnS at the end of the rapid cooling, but is heated to a temperature lower than 345 ° C. this effect is small because the diffusion rate of C is low if you, Fe 3 for Fe 3 C, which precipitated MnS around when heated to a temperature starts to re-dissolved into the steel in excess of 450 ° C. C
The number decreases, and in each case, good aging characteristics cannot be obtained. After reheating, the effect of further accelerating the precipitation of C can be maximized by gradually cooling in the temperature range of 200 to 330 ° C. for 100 seconds or more. C when slowly cooled to a temperature above 330 ° C or below 200 ° C
Since the precipitation of Fe 3 C as Fe 3 C is delayed, a steel sheet with good aging characteristics cannot be manufactured. Also, the time required for this slow cooling is 100
Even if it is less than a second, C does not sufficiently precipitate, so that a steel sheet having good aging characteristics cannot be manufactured.
以上のように、本発明は熱間圧延においてMn量およびＳ
量によって決まる特定の温度域において特定量以上の圧
下率の圧延を加えた後、特定条件の連続焼鈍を行うこと
によって従来1100℃以上のスラブ加熱温度では困難であ
った冷延鋼板の深絞り性および時効特性を優れたものと
することができる。INDUSTRIAL APPLICABILITY As described above, according to the present invention, Mn content and S
The deep drawability of cold-rolled steel sheets, which was conventionally difficult at a slab heating temperature of 1100 ° C or higher, by performing rolling with a rolling reduction of a specific amount or more in a specific temperature range determined by the amount and then performing continuous annealing under specific conditions. And the aging characteristics can be made excellent.
以下に本発明の実施例を比較例と共に示す。Hereinafter, examples of the present invention will be shown together with comparative examples.
実施例１ 第３表に示すAlキルド鋼のスラブを種々の温度に加熱
し、T1の温度範囲内において第４表に示すような種々の
圧下率の圧延を行った後900℃以上で仕上げ、700℃で巻
き取った。さらに、80％の冷間圧延および第１図に示す
ようなヒートパターンの連続焼鈍を施した。この結果得
られた冷延鋼板について、JIS5号引張り試験片を用いて
引張り試験を行い値および時効指数（A.I.）を測定し
た。材質調査結果を第４表に示す。Example 1 The slabs of Al-killed steel shown in Table 3 were heated to various temperatures, rolled at various rolling reductions as shown in Table 4 within the temperature range of T1, and then finished at 900 ° C. or higher, It was wound up at 700 ° C. Further, 80% cold rolling and continuous heat pattern annealing as shown in FIG. 1 were performed. The cold-rolled steel sheet obtained as a result was subjected to a tensile test using a JIS No. 5 tensile test piece to measure the value and aging index (AI). Table 4 shows the results of material inspection.
第４表より熱延条件が本発明の範囲に入っているものは
本発明の範囲外のものに比べて特に1100℃以上のスラブ
加熱温度における深絞り性および時効特性のいずれもス
ラブの加熱温度依存性が少なく、かつ優れていることが
わかる。As shown in Table 4, when the hot rolling conditions are within the scope of the present invention, both the deep drawing property and the aging characteristics at the slab heating temperature of 1100 ° C. or higher are compared with those outside the scope of the present invention. It can be seen that it has little dependence and is excellent.
実施例２ 第５表に示す種々の組成の鋼のスラブを1200℃に加熱
し、各鋼においてT1の温度範囲内で少なくとも50％以上
の圧下率の圧延を行い、さらに圧延を続け900℃で仕上
げた後720℃で巻き取った。さらに、80％の冷間圧延お
よび第１図に示すようなヒートパターンの連続焼鈍を施
した。この結果得られた冷延鋼板について、JIS5号引張
り試験片を用いて引張り試験を行い値および時効指数
（A.I.）を測定した。材質調査結果を第６表に示す。第
５表および第６表より組成が本発明の範囲に入っている
ものは本発明の範囲外のものに比べて深絞り性および時
効特性のいずれも優れていることがわかる。 Example 2 Slabs of steels having various compositions shown in Table 5 were heated to 1200 ° C., rolled in each steel at a rolling reduction of at least 50% or more within a temperature range of T1, and further rolled at 900 ° C. After finishing, it was wound up at 720 ° C. Further, 80% cold rolling and continuous heat pattern annealing as shown in FIG. 1 were performed. The cold-rolled steel sheet obtained as a result was subjected to a tensile test using a JIS No. 5 tensile test piece to measure the value and aging index (AI). Table 6 shows the results of the material investigation. From Tables 5 and 6, it can be seen that those having a composition within the scope of the present invention are superior in both deep drawability and aging characteristics as compared with those outside the scope of the present invention.
実施例３ 第７表に示す組成の鋼のスラブを1200℃に加熱し、1100
℃から圧延を開始し、960℃までに80％の圧下率で圧延
を行った。これを700℃で巻き取った後、さらに80％の
冷間圧延および第４図に示すヒートパターンでtaを60秒
にし、T2,T3,T4,T5,T6,CR1,CR2およびtbを種々変えた連
続焼鈍を施した。この結果得られた冷延鋼板にについ
て、JIS5号引張り試験片を用いて引張り試験を行い値
および時効指数（A.I.）を測定した。連続焼鈍条件およ
び材質調査結果を第８表に示す。第８票より連続焼鈍条
件が本発明の範囲に入っているものは本発明の範囲外の
ものに比べて深絞り性および時効特性のいずれも優れて
いることがわかる。 Example 3 A steel slab having the composition shown in Table 7 was heated to 1200 ° C.
Rolling was started from ℃, and rolled at a reduction rate of 80% up to 960 ℃. After winding this at 700 ℃, 80% cold rolling and the heat pattern shown in Fig.4, ta was set to 60 seconds, and T2, T3, T4, T5, T6, CR1, CR2 and tb were changed variously. Continuous annealing was performed. The cold-rolled steel sheet obtained as a result was subjected to a tensile test using a JIS No. 5 tensile test piece to measure a value and an aging index (AI). Table 8 shows the continuous annealing conditions and the results of material investigation. From the eighth vote, it can be seen that those with continuous annealing conditions within the scope of the present invention are superior in both deep drawability and aging characteristics as compared with those outside the scope of the present invention.
（発明の効果） 以上説明したように、本発明の方法は熱延においてMn量
およびＳ量によって決まる特定の温度域において特定量
以上の圧下率の圧延を行い、さらに特定の条件の連続焼
鈍を行うことによって冷延鋼板の深絞り性および時効特
性を優れたものとすることができる。 (Effects of the Invention) As described above, the method of the present invention performs rolling at a rolling reduction of a specific amount or more in a specific temperature range determined by the amount of Mn and the amount of S in hot rolling, and further performs continuous annealing under specific conditions. By doing so, the deep-drawability and aging characteristics of the cold-rolled steel sheet can be made excellent.
第１図は連続焼鈍のヒートパターンを示す図、第２図は
熱延圧下率の値、時効指数におよぼす影響を示す図、
第３図は巻取温度の値、時効指数におよぼす影響を示
す図、第４図は連続焼鈍のヒートパターンを示す図であ
る。FIG. 1 is a diagram showing a heat pattern of continuous annealing, FIG. 2 is a diagram showing a value of a hot rolling reduction, and an influence on an aging index,
FIG. 3 is a diagram showing the effect on the value of the winding temperature and the aging index, and FIG. 4 is a diagram showing the heat pattern of continuous annealing.
Claims (1)
下,Mn:0.05〜0.25％,S:0.003〜0.020％,Al:0.010〜0.10
％,N:0.0060％以下を含有し、残部がFeおよび不可避的
不純物よりなる鋳片を1100℃以上に加熱し熱延を行い、
鋳片の表面温度が下記式に示すT1の温度域の範囲内にお
いて鋳片の表面温度がT1の温度域の上限に達したときの
板厚に対して圧下率50％以上の圧延を加え、900℃以上
の温度で熱延を終了し、600℃以上800℃以下の温度で巻
き取った後、冷延し、700℃以上900℃以下の温度で焼鈍
し、この温度域から690〜650℃の温度範囲に３〜20℃／
秒で冷却し、続いて200〜340℃の温度範囲に50〜200℃
／秒で冷却し、さらに345〜450℃の温度範囲に加熱し、
この温度範囲から200〜330℃の温度範囲に100秒以上の
時間をかけて徐冷することを特徴とする連続焼鈍による
深絞り性および時効特性の優れた冷延鋼板の製造方法。 （但し、T1の下限は900℃とする）1. A weight ratio of C: 0.010 to 0.038%, Si: 0.04% or less, Mn: 0.05 to 0.25%, S: 0.003 to 0.020%, Al: 0.010 to 0.10.
%, N: 0.0060% or less, the balance consisting of Fe and inevitable impurities is heated to 1100 ° C. or higher and hot rolled,
Surface temperature of the slab in the range of T1 temperature range shown in the following formula, the surface temperature of the slab is rolled at a rolling reduction of 50% or more with respect to the plate thickness when the upper limit of the temperature range of T1 is reached, Finish hot rolling at a temperature of 900 ° C or higher, wind it at a temperature of 600 ° C or higher and 800 ° C or lower, then cold-roll it and anneal it at a temperature of 700 ° C or higher and 900 ° C or lower. Temperature range of 3 to 20 ℃ /
Cools in seconds, then 50-200 ℃ in the temperature range of 200-340 ℃
/ Sec, then heat to the temperature range of 345-450 ℃,
A method for producing a cold-rolled steel sheet having excellent deep drawability and aging characteristics by continuous annealing, which comprises gradually cooling from this temperature range to a temperature range of 200 to 330 ° C over 100 seconds or more. (However, the lower limit of T1 is 900 ° C)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10063490A JPH0762180B2 (en) | 1990-04-17 | 1990-04-17 | Method for producing cold-rolled steel sheet with excellent deep patterning property and aging characteristics by continuous annealing |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10063490A JPH0762180B2 (en) | 1990-04-17 | 1990-04-17 | Method for producing cold-rolled steel sheet with excellent deep patterning property and aging characteristics by continuous annealing |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH04327A JPH04327A (en) | 1992-01-06 |
| JPH0762180B2 true JPH0762180B2 (en) | 1995-07-05 |
Family
ID=14279267
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP10063490A Expired - Fee Related JPH0762180B2 (en) | 1990-04-17 | 1990-04-17 | Method for producing cold-rolled steel sheet with excellent deep patterning property and aging characteristics by continuous annealing |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0762180B2 (en) |
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|---|---|---|---|---|
| CN112281085A (en) * | 2020-09-17 | 2021-01-29 | 中南大学 | Preparation method of SiC-coated carbon fiber reinforced metal matrix composite material |
-
1990
- 1990-04-17 JP JP10063490A patent/JPH0762180B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH04327A (en) | 1992-01-06 |
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