JPS5810447B2 - Manufacturing method by continuous annealing of cold-rolled steel sheets with excellent workability and aging resistance - Google Patents
Manufacturing method by continuous annealing of cold-rolled steel sheets with excellent workability and aging resistanceInfo
- Publication number
- JPS5810447B2 JPS5810447B2 JP11873978A JP11873978A JPS5810447B2 JP S5810447 B2 JPS5810447 B2 JP S5810447B2 JP 11873978 A JP11873978 A JP 11873978A JP 11873978 A JP11873978 A JP 11873978A JP S5810447 B2 JPS5810447 B2 JP S5810447B2
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- Prior art keywords
- temperature
- rolled steel
- cold
- seconds
- aging resistance
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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
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/52—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for wires; for strips ; for rods of unlimited length
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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)
Description
【発明の詳細な説明】
本発明は急速加熱、急速冷却を採用した連続焼鈍法にお
いて急速冷却開始から過時効処理にいたる間で特殊な熱
サイクルを採用することによって高加工性及び高耐時効
性を備えた冷延鋼板の製造方法に関するものである。Detailed Description of the Invention The present invention achieves high workability and high aging resistance by adopting a special thermal cycle from the start of rapid cooling to overaging treatment in a continuous annealing method that employs rapid heating and rapid cooling. The present invention relates to a method for manufacturing a cold-rolled steel sheet.
従来の加工用冷延鋼板の焼鈍方法としてはバッチ(箱)
焼鈍法によるのが通常であったが、最近では連続焼鈍方
法による加工用冷延薄鋼板の製造が可能となっている。Batch (box) is the conventional method of annealing cold-rolled steel sheets for processing.
Usually, the annealing method was used, but recently it has become possible to manufacture cold-rolled thin steel sheets for processing using the continuous annealing method.
現在、採用されている連続焼鈍方式は大別して2種類あ
り、1つは徐加熱−均熱一徐冷一過時効処理を5分〜1
0分程度かけておこなうもの、もう一つは徐加熱−均熱
−常温まで急冷−再加熱過時効を4分程度かけておこな
うものである。Currently, there are two types of continuous annealing methods in use: one is slow heating, soaking, slow cooling, and passing aging treatment for 5 minutes to 1
One method involves slow heating, soaking, rapid cooling to room temperature, and reheating overaging, which takes about 4 minutes.
いずれにしても4分程度以上の処理時間が必要である。In any case, a processing time of about 4 minutes or more is required.
この処理時間が長いことはとりもなおさず連続焼鈍設備
そのものとして長大なものが必要であるということであ
り、膨大な建設費がかかるさいうことである。This long processing time also means that a long continuous annealing facility is required, which incurs enormous construction costs.
本出願人らは従来の連続焼鈍設備に比べて更にコンパク
トで建設費の安いものはできないだろうかと種々検討し
た結果、急速加熱−均熱一過時効温度への急冷−過時効
処理のサイクルを採用すれば100秒前後の極めて短時
間の焼鈍でむしろ従来の焼鈍方式以上の材質をもった鋼
板を製造しうろことを見いだした。As a result of various studies, the applicants adopted a cycle of rapid heating, soaking, rapid cooling to over-aging temperature, and over-aging treatment. It was discovered that it would be possible to produce steel sheets with material properties better than those achieved by conventional annealing methods by annealing in an extremely short time of around 100 seconds.
この新連続焼鈍方式の詳細の一部は特願昭53−306
8に記載されているとおりである。Some of the details of this new continuous annealing method are disclosed in Japanese Patent Application No. 53-306.
As described in 8.
本発明者らは急速加熱冷却を採用した新連続焼鈍方式を
更に詳細に検討した結果、急冷から過時効処理のいたる
間の熱サイクルを工夫すれば一層高い加工性と耐時効性
が得られることを見いだしたものである。As a result of a more detailed study of a new continuous annealing method that employs rapid heating and cooling, the present inventors found that even higher workability and aging resistance can be obtained by devising the thermal cycle from rapid cooling to overaging treatment. This is what I found.
先ず、本発明で用いる熱延鋼帯の成分組成について説明
する。First, the composition of the hot rolled steel strip used in the present invention will be explained.
本発明が対象とする加工用冷延鋼板の出発鋼材は通常の
ものであるが、特に本発明は以下の理由によりC0,0
8%以下、Mn0.08〜0.4%、固溶N0.002
5%以下を含む熱延鋼帯を出発材とするものである。The starting steel material for cold-rolled steel sheets for processing, which is the object of the present invention, is a normal steel material, but in particular, the present invention uses C0,0
8% or less, Mn 0.08-0.4%, solid solution N 0.002
The starting material is a hot rolled steel strip containing 5% or less.
Cは従来から含有量が少くなるに従って、軟質化するこ
とが知られており、本発明の場合は、C0.08%以下
で加工性と耐時効性の優れた冷延鋼板が得られる。It has been known that C becomes softer as its content decreases, and in the case of the present invention, a cold-rolled steel sheet with excellent workability and aging resistance can be obtained with a C content of 0.08% or less.
Mnは熱間圧延時にSが誘発する脆化を防止するために
必要な元素であり、0.08%以上含有する必要がある
か、0.4%を超えると材質が硬化し加工性が損なわれ
る。Mn is an element necessary to prevent embrittlement induced by S during hot rolling, and it is necessary to contain 0.08% or more, or if it exceeds 0.4%, the material will harden and workability will be impaired. It will be done.
固溶窒素は固溶炭素とともに耐時効性を決定する成分で
、固溶量が高くなるに従って耐時効性は悪化し、熱延鋼
帯中の固溶窒素が25 ppmより多くなると固溶窒素
による時効劣化量が大きくなり過ぎ、後述する本発明の
急速加熱による連続焼鈍方法によって固溶炭素による時
効劣化を防止し得ても、加工性と耐時効性を同時に満足
する優れた鋼板は得られなくなる。Solute nitrogen is a component that determines aging resistance together with solute carbon, and as the amount of solute increases, aging resistance deteriorates.When the amount of solute nitrogen in a hot rolled steel strip exceeds 25 ppm, the aging resistance deteriorates due to solute nitrogen. The amount of aging deterioration becomes too large, and even if aging deterioration due to solid solute carbon can be prevented by the continuous annealing method using rapid heating of the present invention described later, it is no longer possible to obtain an excellent steel plate that satisfies workability and aging resistance at the same time. .
次に本発明の特徴点である連続焼鈍工程中、特に急冷か
ら過時効処理にいたる間の熱サイクルについて説明する
。Next, the thermal cycle during the continuous annealing process, which is a feature of the present invention, particularly from rapid cooling to overaging treatment will be explained.
過時効処理の意図するところは加熱−均熱焼鈍時に炭化
物の一部が溶解して、増加した固溶炭素を再析出させて
高い延性及び耐時効性を確保しようとするところにある
。The purpose of the over-aging treatment is to ensure high ductility and aging resistance by dissolving some of the carbides during heating and soaking annealing and re-precipitating the increased solid solution carbon.
従って、より迅速にかつ加工性にとって好ましい析出分
散形態にセメンタイトの析出をするのにはいかに熱サイ
クルをコントロールすればよいかが、検討の主眼になる
。Therefore, the main focus of the study is how to control the thermal cycle in order to precipitate cementite more quickly and in a precipitation dispersion form that is favorable for workability.
フェライト中に存在するセメンタイトと平衡する固溶濃
度限以上に存在する固溶炭素は、過時効時間の経過とと
もにセメンタイトとして析出しフェライト中の固溶炭素
濃度は低下する。The solid solution carbon present in the ferrite at a concentration higher than the solid solution concentration limit that is in equilibrium with the cementite present in the ferrite precipitates as cementite with the passage of over-aging time, and the solid solution carbon concentration in the ferrite decreases.
析出時の炭素の拡散速度は温度に大きく影響され析出速
度の面からみれば温度は高い方が早く拡散をして析出処
理時間を短かくするためには有利であるが、平衡固溶限
も又温度とともに上昇するので析出核が少なくなり全体
としての炭化物の析出速度は小さくなる。The diffusion rate of carbon during precipitation is greatly affected by temperature, and from the standpoint of precipitation rate, higher temperatures are advantageous for faster diffusion and shorter precipitation processing time, but the equilibrium solid solubility limit also increases. Furthermore, since the temperature increases with temperature, the number of precipitation nuclei decreases, and the overall precipitation rate of carbides decreases.
従って析出処理温度としては最適の温度を選ぶととが必
要である。Therefore, it is necessary to select the optimum temperature for the precipitation treatment.
これらのことから過時効処理温度として350°C〜5
00℃を選ぶものである。For these reasons, the overaging treatment temperature is 350°C~5.
00°C is selected.
炭素の拡散速度の問題と同時に析出核の問題も炭素の析
出を考える上で重要であることは既にのべたところであ
るが、析出核となるところは転位、空孔、粒界などがあ
るがこれらの析出核が高密度に分散していれば析出する
までの必要拡散距離が短かくて済むので析出が促進され
ることになる。As already mentioned, the issue of precipitation nuclei is important when considering carbon precipitation as well as the issue of carbon diffusion rate. If the precipitation nuclei are dispersed at a high density, the required diffusion distance for precipitation will be short, so precipitation will be promoted.
さて、本出願人らの発明である急速加熱−均熱−過時効
温度への急冷−過時効処理の短時間サイクルの焼鈍(特
願昭53−3068)において一層高い加工性と耐時効
性を鋼板に付与する新しい熱サイクルについて以下に例
を挙げて説明する。Now, in the short-term annealing cycle of rapid heating, soaking, rapid cooling to the overaging temperature, and overaging treatment (patent application No. 53-3068), which is an invention of the present applicants, even higher workability and aging resistance have been achieved. A new thermal cycle applied to a steel plate will be explained below using an example.
第1図の熱サイクルにおいて730℃までを90℃/
secの急速加熱で昇温し、730℃で15秒間均熱後
600℃と室温までの間の各温度へ150°c/ Se
Cの急速冷却し、その温度で5秒間保持したのちに40
0℃の過時効処理温度へ40℃/ secで冷却又は昇
温しで過時効処理を施した。In the thermal cycle shown in Figure 1, up to 730℃, 90℃/
After heating at 730℃ for 15 seconds, heat to each temperature between 600℃ and room temperature at 150℃/Se.
After rapid cooling to 40°C and holding at that temperature for 5 seconds,
An overaging treatment was performed by cooling or heating at a rate of 40°C/sec to an overaging treatment temperature of 0°C.
使用した材料は第1表に示す成分を有するA7キルド鋼
であり2.8 mmの熱延板を0.8mmにまで冷間圧
延したものを用いた。The material used was A7 killed steel having the components shown in Table 1, which was obtained by cold rolling a 2.8 mm hot-rolled plate to 0.8 mm.
1.0%の調質圧延後の材質に及ぼす一次急冷終点の影
響を第2図に、又析出したセメンタイトの析出分散状態
は第3図の写真図に示す。The effect of the end point of the primary quenching on the material quality after 1.0% temper rolling is shown in FIG. 2, and the state of precipitation and dispersion of precipitated cementite is shown in the photograph of FIG.
これらによると、一次冷却終点が200℃以下の場合に
はY、P−E7の変化に示されるように、極めて短時間
内に固溶炭素は低下して、Y、P−Elは0.75%以
下になって時効特性は効率よく向上させることができる
。According to these, when the primary cooling end point is 200°C or lower, as shown by the change in Y and P-E7, the solid solution carbon decreases within a very short time, and Y and P-El become 0.75. % or less, the aging characteristics can be efficiently improved.
しかし、Y、Pは高く時効前及び時効後の延性はともに
劣化が大きいので、一次冷却終点を200℃以下にする
ことは好ましいことではない。However, since Y and P are high and the ductility both before and after aging deteriorates significantly, it is not preferable to set the primary cooling end point to 200° C. or lower.
材質は硬質であるが、時効特性は良好となるのは第3図
のセメンタイトの析出状態に示されるように微細なセメ
ンタイトが粒内に多数析出するためである。Although the material is hard, the aging properties are good because a large number of fine cementites are precipitated within the grains, as shown in the state of cementite precipitation in FIG.
一次冷却終点が300℃になるとY、P−E7は200
℃以下とほぼ同じであり時効特性を高めることができる
。When the primary cooling end point is 300℃, Y, P-E7 is 200
It is almost the same as below ℃, and the aging characteristics can be improved.
一方、第3図に示されているように、大部分のセメンタ
イトは粒界に出ていてかつ一部の微細セメンタイトは粒
内にある状態の場合であり、このためにY、Pは低くて
軟質でElは高い値を有している。On the other hand, as shown in Figure 3, most of the cementite is present at the grain boundaries, and some fine cementite is inside the grains, so Y and P are low. It is soft and has a high El value.
又、時効後も延性は高い値を有している。Furthermore, the ductility remains high even after aging.
一次冷却終点温度が400°C以上になると終点温度の
上昇とともにY、P−Elは大きくなってしまう。When the primary cooling end point temperature becomes 400°C or more, Y and P-El increase as the end point temperature increases.
更に、一次冷却終点温度の上昇とともに延性は劣化する
。Furthermore, the ductility deteriorates as the primary cooling end point temperature increases.
とくに時効後の延性は400°C以上で悪くなる。In particular, the ductility after aging deteriorates at temperatures above 400°C.
更に説明を加えれば、一次冷却終点の保持温度より過時
効処理温度を50℃以上高くするようにしている。To explain further, the overaging treatment temperature is set to be 50° C. or more higher than the holding temperature at the end point of the primary cooling.
これは過時効処理温度より50℃以下に一次冷却終点を
とることによって、炭素の過飽和度を高めておいて微細
なセメンタイトの析出核を多数作ることにある。This is because by setting the primary cooling end point to 50° C. or lower than the overaging treatment temperature, the degree of carbon supersaturation is increased and a large number of fine cementite precipitation nuclei are created.
いいかえれば最も効率的な過時効処理温度よりも、析出
核を最も効率的に作る温度は50°C以下低い温度であ
るということである。In other words, the temperature at which precipitation nuclei are most efficiently formed is 50° C. or lower than the most efficient overaging treatment temperature.
これらを総合すれば、400℃過時効処理の場合、一次
冷却終点を250℃〜350℃にとれば軟質で延性が高
く、かつ時効特性が優れたものが得られることになるの
である。Taken together, in the case of 400°C overaging treatment, if the primary cooling end point is set at 250°C to 350°C, a product that is soft, has high ductility, and has excellent aging properties can be obtained.
以上例をあげて本発明の詳細な説明したが、この発明の
特徴は約600℃から均熱温度までの高温部分での加熱
速度を40℃/sec以上にすれば一層発揮される。Although the present invention has been described in detail with reference to the examples above, the features of the present invention can be further exhibited if the heating rate in the high temperature section from about 600° C. to the soaking temperature is set to 40° C./sec or more.
これは急速加熱を採用することによって再結晶開始から
粒生長にいたる間でセメンタイトからの炭素の溶出を押
えて均一に粒成長のし易い再結晶粒が作られるからであ
る。This is because by employing rapid heating, elution of carbon from cementite is suppressed from the start of recrystallization to grain growth, and recrystallized grains that are easy to grow uniformly are created.
尚、加熱速度の上限は、冶金学的には特に限定する理由
はないが、加熱速度が150℃/secを超えると加熱
の到達温度即ち均熱温度の制御がむずかしく、温度のバ
ラツキが大きくなり、安定した材質が得られなくなる。Although there is no reason to specifically limit the upper limit of the heating rate from a metallurgical point of view, if the heating rate exceeds 150°C/sec, it will be difficult to control the temperature reached by heating, that is, the soaking temperature, and the temperature will vary widely. , stable material cannot be obtained.
均熱温度は680℃〜900℃の間であれば充分である
。It is sufficient that the soaking temperature is between 680°C and 900°C.
680℃よりも低いと短時間で充分なる粒成長ができな
いし、900℃以上では焼鈍中にγ変態する領域が増え
るので焼鈍後の鋼板の材質が非常に悪くなる。If it is lower than 680°C, sufficient grain growth cannot be achieved in a short period of time, and if it is higher than 900°C, the region undergoing γ transformation increases during annealing, resulting in a very poor quality of the steel sheet after annealing.
これらのことから均熱温度は68000〜900°Cに
限定するものである。For these reasons, the soaking temperature is limited to 68,000 to 900°C.
均熱時間は1秒〜30秒の間であればよい。The soaking time may be between 1 second and 30 seconds.
従来の連続焼鈍方法のように10°C/sec程度の速
度で徐加熱をする場合には、粒成長を充分に行なわせる
ために均熱時間は40秒程度必要であり、現在の実操業
でも40秒前後の均熱時間が採用されている。When slow heating is performed at a rate of about 10°C/sec as in the conventional continuous annealing method, a soaking time of about 40 seconds is required to ensure sufficient grain growth, and even in current actual operations, A soaking time of around 40 seconds is used.
しかし、本発明のように40°C/SeC以上の急速加
熱を採用する場合には均一粒成長が充分短時間でおこる
ので本発明では均熱時間として1秒〜30秒とするもの
である。However, when rapid heating of 40° C./SeC or more is employed as in the present invention, uniform grain growth occurs in a sufficiently short time, so the soaking time is set to 1 second to 30 seconds in the present invention.
一次冷却速度はある程度早くなければ本発明の効果は発
揮されないが、すくなくとも600℃以上の温度から一
次冷却終点温度までの範囲を35℃/sec以上の冷却
速度で冷却すれば、本発明の効果は発揮される。Although the effect of the present invention cannot be exhibited unless the primary cooling rate is fast to a certain extent, the effect of the present invention can be achieved if the cooling rate is at least 35°C/sec or more from a temperature of 600°C or higher to the primary cooling end point temperature. Demonstrated.
尚、冷却速度の上限は、本発明の如く、急冷の終点温度
を制御する場合には、冶金学的に限定する理由はないが
、冷却速度が250℃/secを超える場合には、急冷
の終点温度を250°C〜400℃に制御することが困
難となる。There is no metallurgical reason to limit the upper limit of the cooling rate when controlling the end point temperature of quenching as in the present invention, but if the cooling rate exceeds 250°C/sec, the upper limit of quenching It becomes difficult to control the end point temperature between 250°C and 400°C.
その結果材質が硬質化したり、耐時効性が損なわれるこ
とになる。As a result, the material becomes hard and the aging resistance is impaired.
更に一次急冷終点温度での保持時間は冷却速度を35°
C/sec以上にすれば極めて短時間でセメンタイトの
析出核を作るという作用は完了するということもわかっ
た。Furthermore, for the holding time at the primary quenching end point temperature, the cooling rate was changed to 35°.
It has also been found that the action of creating cementite precipitation nuclei can be completed in an extremely short time if the temperature is set to C/sec or more.
したがって10秒より長い時間の保定をおこなっても全
体の焼鈍時間が長くなるばかりで何ら利点はない。Therefore, even if holding time is longer than 10 seconds, the entire annealing time will only become longer and there will be no advantage.
一次急冷終点温度における保持時間は10秒以下で充分
である。A holding time of 10 seconds or less at the primary quenching end point temperature is sufficient.
更に実施例を挙げながら本発明の詳細な説明しよう。Further, the present invention will be explained in detail by giving examples.
実施例 I
C:0.055%、Mn : 0.28%、P:0.0
10%、s:o、oos%、N60.0022%の成分
をもつ転炉溶製キャップド鋼より得られた板厚0.8m
mの冷延板を素材として、730℃で15秒の焼鈍後、
150℃/secで300℃まで急冷した後再加熱して
400℃で60秒の過時効処理を施す熱サイクルにおい
て加熱速度を10℃/sec〜90℃/secまでかえ
て本発明における加熱速度の効果を調査した。Example I C: 0.055%, Mn: 0.28%, P: 0.0
Plate thickness 0.8 m obtained from converter melted capped steel with components of 10%, s:o, oos%, N60.0022%
After annealing at 730°C for 15 seconds using a cold-rolled plate of m as the material,
The heating rate in the present invention was changed by changing the heating rate from 10°C/sec to 90°C/sec in a thermal cycle in which the temperature was rapidly cooled to 300°C at 150°C/sec, then reheated and overaged for 60 seconds at 400°C. We investigated the effects.
又、比較のために均熱焼鈍後直液400℃の過時効処理
温度へ急冷した材料についても調査した。For comparison, we also investigated materials that were directly cooled to an overaging treatment temperature of 400°C after soaking annealing.
その結果として、第4図に全伸び特性値の変化を示す。As a result, changes in the total elongation characteristic values are shown in FIG.
特に加熱速度が40℃/sec以上の本発明の方法にお
いて全伸びは比較の方法よりもよいことがわかる。In particular, it can be seen that the total elongation is better in the method of the present invention in which the heating rate is 40° C./sec or more than in the comparative method.
実施例 2
1 C:0.039%、Mn : 0.24%、P:
0.011%、S:0.005%、N:0.0045%
、5OlAl:0055%の成分をもつ転炉溶製Alギ
ルド鋼を捲取温度735℃で2.8mmの熱延板に仕上
げ、これを0.8龍にまで冷間圧延後、表−2中に記さ
れている条件で各種の熱処理を施した。Example 2 1 C: 0.039%, Mn: 0.24%, P:
0.011%, S: 0.005%, N: 0.0045%
, 5OlAl: Al guild steel made in a converter having a composition of 0055% was finished into a 2.8mm hot-rolled plate at a winding temperature of 735°C, and after cold rolling it to a thickness of 0.8mm, Various heat treatments were performed under the conditions described in .
実験符号A、B、C,Dを比較すると均熱時間の効果が
わかる。Comparing experimental codes A, B, C, and D, the effect of soaking time can be seen.
均熱時間は長くなる程、降伏点(Y、P)は低くなり軟
質化する。As the soaking time becomes longer, the yield point (Y, P) becomes lower and the material becomes softer.
しかし、30秒と60秒の均熱時間の差の材質に及ぼす
効果はほとんどないといってよく、60秒といった長時
間の均熱時間をとる必要はない。However, it can be said that the difference in soaking time between 30 seconds and 60 seconds has almost no effect on the material, and there is no need to take a soaking time as long as 60 seconds.
従って均熱時間は30秒以下であればよい。Therefore, the soaking time may be 30 seconds or less.
次に実験符号B、E、Fを比較すると一次急冷開始温度
の効果がわかる。Next, by comparing experimental codes B, E, and F, the effect of the primary quenching start temperature can be seen.
即ち、Y、P、r値等の値はB、E、Fの間でほとんど
差はないが、Y、P−E7.E7において差がでてくる
。That is, there is almost no difference in Y, P, r values, etc. between B, E, and F, but Y, P-E7. The difference appears at E7.
一次急冷開始温度が600℃以上のB、EにおいてはY
、P’−E7は1.0以下になって遅時効性となるが、
一次急冷開始温度が500℃になるとY、P−Ell、
3と高くなり時効性が悪くなる、又同時にEAI’も低
くなる。Y for B and E where the primary quenching start temperature is 600℃ or higher
, P'-E7 becomes 1.0 or less, resulting in slow aging, but
When the primary quenching start temperature reaches 500℃, Y, P-Ell,
3, the aging property deteriorates, and at the same time, the EAI' also decreases.
B、G、Hを比較すると冷却速度の効果がわかる。Comparing B, G, and H shows the effect of cooling rate.
冷却速度の小さいGではY、Pは高くY、P−EA’も
太きくE7も低い。At G, where the cooling rate is low, Y and P are high, Y and P-EA' are also thick, and E7 is low.
これに対して冷却速度が40°C/S以上と大きいH,
BではY、PとY、P−E7は低くかつE7は大きい。On the other hand, H, which has a large cooling rate of 40°C/S or more,
In B, Y, P and Y, P-E7 are low and E7 is large.
本発明のように短時間過時効の場合には40℃/S以上
の冷却速度が必要となる。In the case of short-time overaging as in the present invention, a cooling rate of 40° C./S or more is required.
I、J、にとして、均熱温度が850℃の場合と950
℃の場合が記されている。For I, J, when the soaking temperature is 850℃ and 950℃
The case of °C is described.
I、Jの850℃の場合はY、Pが低く軟質になり、7
値も高くなるといった特徴があるが均熱温度が900℃
よりも高い950℃の場合にはr値は極端に低くなる。In the case of I and J at 850°C, Y and P are low and soft, and 7
Although the value is also high, the soaking temperature is 900℃.
When the temperature is higher than 950°C, the r value becomes extremely low.
したがって均熱温度は700℃から900℃の範囲にあ
ればよい。Therefore, the soaking temperature may be in the range of 700°C to 900°C.
次にB、L、Mを比較すると過時効処理時間の効果がわ
かる。Next, by comparing B, L, and M, the effect of the overaging treatment time can be seen.
過時効処理時間は長くなるほど、Y、Pは低くなり軟質
化し、延性も高くなる。The longer the overaging treatment time, the lower the Y and P values, the softer the material, and the higher the ductility.
しかし、L2Mの120秒と180秒を比較すると材質
的にはほとんど差がない。However, when comparing 120 seconds and 180 seconds of L2M, there is almost no difference in terms of materials.
従って、過時効処理時間としては120秒以下で充分で
ある。Therefore, 120 seconds or less is sufficient as the overaging treatment time.
このように本発明方法に従って連続焼鈍をすれば加工性
及び耐時効性の優れた冷延鋼板が得られる。As described above, if continuous annealing is performed according to the method of the present invention, a cold rolled steel sheet with excellent workability and aging resistance can be obtained.
第1図は一次冷却終点温度の影響調査熱サイクルを示す
図、第2図は一次急冷終点温度の材質に及ぼす影響を示
す図、第3図はセメンタイトの析出状態に及ぼす一次急
冷終点温度の影響を示す金属組織の顕微鏡写真図(×8
00)、第4図は全伸びに及ぼす加熱速度の影響を示す
図である。Figure 1 shows the thermal cycle for investigating the influence of primary cooling end point temperature, Figure 2 shows the influence of primary quenching end point temperature on material quality, and Figure 3 shows the effect of primary quenching end temperature on the precipitation state of cementite. Microscopic photograph of metal structure showing (×8
00), FIG. 4 is a diagram showing the influence of heating rate on total elongation.
Claims (1)
溶N0.0025%以下を含有する熱延鋼帯を冷間圧延
し、得られた冷延鋼帯を連続焼鈍するに際して、40°
C/sec〜150°C/secの加熱速度で680℃
〜900℃に加熱し、1秒〜30秒間均熱し、その後2
50°C〜400℃の温度に、すくなくとも600℃以
下の温度範囲を35℃/see〜250℃/secの冷
却速度で冷却し、その温度で10秒間以下の時間保持し
、しかる後に50℃以上の再加熱により350°C〜5
00℃に昇温し、120秒以内の過時効処理を施こすこ
とを特徴とする加工性及び耐時効性の優れた冷延鋼板の
製造方法。1 When cold rolling a hot rolled steel strip containing 0.08% or less of C, 0.08 to 0.4% of Mn, and 0.0025% or less of solid solution N, and continuously annealing the obtained cold rolled steel strip, 40 °
680°C with a heating rate of C/sec to 150°C/sec
Heat to ~900℃, soak for 1 second to 30 seconds, then 2
Cool to a temperature of 50°C to 400°C at a cooling rate of at least 600°C or less at a cooling rate of 35°C/see to 250°C/sec, hold at that temperature for 10 seconds or less, and then cool to 50°C or higher. 350°C~5 by reheating
A method for producing a cold-rolled steel sheet with excellent workability and aging resistance, which comprises raising the temperature to 00°C and performing an overaging treatment within 120 seconds.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP11873978A JPS5810447B2 (en) | 1978-09-27 | 1978-09-27 | Manufacturing method by continuous annealing of cold-rolled steel sheets with excellent workability and aging resistance |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP11873978A JPS5810447B2 (en) | 1978-09-27 | 1978-09-27 | Manufacturing method by continuous annealing of cold-rolled steel sheets with excellent workability and aging resistance |
Publications (2)
Publication Number | Publication Date |
---|---|
JPS5544584A JPS5544584A (en) | 1980-03-28 |
JPS5810447B2 true JPS5810447B2 (en) | 1983-02-25 |
Family
ID=14743861
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP11873978A Expired JPS5810447B2 (en) | 1978-09-27 | 1978-09-27 | Manufacturing method by continuous annealing of cold-rolled steel sheets with excellent workability and aging resistance |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPS5810447B2 (en) |
Families Citing this family (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS5810972B2 (en) * | 1978-10-13 | 1983-02-28 | 新日本製鐵株式会社 | Manufacturing method by continuous annealing of cold-rolled steel sheets with excellent deep drawability |
JPS57207122A (en) * | 1981-06-12 | 1982-12-18 | Nippon Kokan Kk <Nkk> | Production of cold rolled steel plate having superior aging resistance by continuous annealing |
JPH0826402B2 (en) * | 1991-01-22 | 1996-03-13 | 新日本製鐵株式会社 | Method for producing Al-killed cold-rolled steel sheet with excellent surface properties by continuous annealing |
-
1978
- 1978-09-27 JP JP11873978A patent/JPS5810447B2/en not_active Expired
Also Published As
Publication number | Publication date |
---|---|
JPS5544584A (en) | 1980-03-28 |
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