JPH0418013B2 - - Google Patents
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- Publication number
- JPH0418013B2 JPH0418013B2 JP57082281A JP8228182A JPH0418013B2 JP H0418013 B2 JPH0418013 B2 JP H0418013B2 JP 57082281 A JP57082281 A JP 57082281A JP 8228182 A JP8228182 A JP 8228182A JP H0418013 B2 JPH0418013 B2 JP H0418013B2
- Authority
- JP
- Japan
- Prior art keywords
- less
- ridging
- hot
- temperature
- annealing
- 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.)
- Expired - Lifetime
Links
- 229910000831 Steel Inorganic materials 0.000 claims description 23
- 239000010959 steel Substances 0.000 claims description 23
- 238000001953 recrystallisation Methods 0.000 claims description 20
- 238000000137 annealing Methods 0.000 claims description 17
- 230000009467 reduction Effects 0.000 claims description 12
- 229910001220 stainless steel Inorganic materials 0.000 claims description 11
- 238000005097 cold rolling Methods 0.000 claims description 6
- 238000004519 manufacturing process Methods 0.000 claims description 5
- 229910000859 α-Fe Inorganic materials 0.000 claims description 5
- 229910052799 carbon Inorganic materials 0.000 claims description 4
- 230000007547 defect Effects 0.000 claims description 3
- 239000010935 stainless steel Substances 0.000 claims description 3
- 238000005098 hot rolling Methods 0.000 description 27
- 238000000034 method Methods 0.000 description 21
- 230000000694 effects Effects 0.000 description 17
- 238000005096 rolling process Methods 0.000 description 7
- 230000008901 benefit Effects 0.000 description 5
- 238000010438 heat treatment Methods 0.000 description 5
- 150000004767 nitrides Chemical class 0.000 description 5
- 238000012545 processing Methods 0.000 description 5
- 239000000463 material Substances 0.000 description 4
- 229910001566 austenite Inorganic materials 0.000 description 3
- 238000005260 corrosion Methods 0.000 description 3
- 230000007797 corrosion Effects 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 239000000047 product Substances 0.000 description 3
- 238000011084 recovery Methods 0.000 description 3
- 239000006104 solid solution Substances 0.000 description 3
- 229910000963 austenitic stainless steel Inorganic materials 0.000 description 2
- 238000005266 casting Methods 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 239000013078 crystal Substances 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 150000001247 metal acetylides Chemical class 0.000 description 2
- 239000002244 precipitate Substances 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 238000009825 accumulation Methods 0.000 description 1
- 230000002301 combined effect Effects 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 230000002542 deteriorative effect Effects 0.000 description 1
- 239000012467 final product Substances 0.000 description 1
- 238000011835 investigation Methods 0.000 description 1
- 229910001105 martensitic stainless steel Inorganic materials 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000005498 polishing Methods 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 238000007788 roughening Methods 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 238000010583 slow cooling Methods 0.000 description 1
- 238000009864 tensile test Methods 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
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
- C21D8/0205—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips of ferrous alloys
Landscapes
- 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
本発明はリジングと熱間ロール焼付き疵のない
フエライト系ステンレス薄鋼板の製造方法に関す
るものである。
フエライト系ステンレス薄鋼板はオーステナイ
ト系ステンレス鋼に比べて安価に澄んだ色調を有
しているので自動車や家庭用の器具の部品などに
広く使用されている。しかしフエライト系ステン
レス鋼は部品製造において、絞り加工や引張り加
工を受けるとリジングあるいはローピングと称さ
れる凹凸の縞模様が発生して外観を著しく損なう
という欠点を有している。このリジングの防止方
法については非常に多くの研究がなされ種々の提
案が行なわれているが、その主たる考え方は、熱
延時の歪をできるだけ多く残留させ、続く熱延板
焼鈍での再結晶を促進させ、リジングの原因とな
る鋳造組織を破壊させようとするものである。具
体的には低温での熱延を施こす方法(例えば特公
昭45−34016号公報参照)が提案されており、ま
たTi,Nb等を添加した上での高温短時間焼鈍方
法(例えば、特開昭51−149116号公報、特公昭55
−6086号公報)が提案されているし、さらにこれ
らの方法を組合わせた提案(例えば特開昭56−
123527号公報)もなされている。しかし、これら
の方法はリジングの軽減には効果を有するものの
オーステナイト系ステンレス鋼の場合のようにリ
ジングを皆無にするためには決定的なものではな
い。
前記した考え方とは異なるが、熱延板焼鈍時に
一旦オーステナイト相を現出せしめる方法(特公
昭48−24611号公報)はリジング防止対策として
非常に優れているもののオーステナイト相をフエ
ライ相に変態させるために非常に遅い冷却を行な
うかあるいは変態温度以下で長時間加熱する必要
があるなど生産性を著しく阻害せざるを得ない。
本発明は以上に示した方法とは異なりNbを添
加したフエライト単相ステンレス鋼において熱延
時も含めて再結晶を繰り返すことによつてリジン
グの原因となる鋳造組織を破壊し、リジング性を
改善しリジングを皆無にしようとするものであ
る。
即ち本発明はC0.015%以下、N0.015%以上、
0.035%以下、Nb0.2%以上でかつCとNの重量%
の和の8倍以上1.0%以下、Cr10%以上22%以下
を含むフエライト系ステンレス鋼スラブを1100℃
以上1250℃以下に加熱し、1000℃以上にて1パス
当たりの圧下率30%以上60%未満の圧下を少くと
も1回以上含んで熱延後、900℃以上1100℃未満
にて10分以内の熱延板焼鈍を施し、しかる後冷延
するかあるいは1回以上の中間焼鈍を含んで冷延
し、再結晶焼鈍を行なうことを特徴とするリジン
グと熱間ロール焼付き疵のないフエライト系ステ
ンレス薄鋼板の製造方法を要旨とするものであ
る。
Nbを添加したフエライト系ステンレス鋼はリ
ジング性に優れていることは既に公知(特公昭38
−16301号公報)であるが、Nb添加のみでは決定
的でないことも周知である。本発明は、Nb添加
鋼の再結晶温度が高い点を利用し、従来指向され
ている低温熱延ではなく、むしろ高温で加熱し熱
延して熱延中の再結晶を促進させ、リジングの原
因となる鋳造組織を破壊するところに特徴を有す
る。Nbを含まない鋼の場合、再結晶温度は低い
ものの高温での熱延では再結晶を起こす程歪が蓄
積されず回復のみ起こることになりやすい上、低
温熱延を行なうと歪は蓄積するが熱延時に再結晶
を起こしにくくなるため、本発明の特徴を具現す
るのは困難である。C含有量が高く、高温でオー
ステナイト相の現われる鋼では再結晶の効果はあ
るが、鋳造組織をこわす程にはならない。
次に本発明者らはNbの析出物である炭化物、
窒化物の効果を検討した。その結果、1100℃以上
で析出するのは主として窒化物であることを見出
し、それが結晶粒の粗大化防止と歪蓄積の核にな
つているものと推定した。この知見に基づき、C
およびN量について検討した。
第1図はCが0.01%以下の19Cr−0.4Nb鋼のリ
ジング高さに及ぼすNの影響を示した図である。
図中●印はリジング高さが加工肌荒れ高さ2μ以
下であるため測定不可能であるため一律に1.5μの
点にプロツトしたものである。第1図の試験条件
は○印、●印については1200℃のスラブ加熱、熱
延の第1パスで40〜45%の圧下率での圧下、熱延
板の厚さは4mm、熱延板焼鈍は980℃×2min、冷
延は中間焼鈍を1回はさんだいわゆる2回冷延
で、0.5mmの再結晶焼鈍材についてJIS5号引張り
試験片にて20%引張り加工を施し測定した。×印
については熱延の圧下率をすべて30%未満とした
例である。
第1図においてリジング高さはN量0.015%以
上で加工肌荒れ高さ2μ以下となつて、実質的に
リジングなしのレベルに達する。またNの効果は
熱延で高圧下を行なつた場合のみ現われ、両者の
複合効果の大きいことがわかる。
第2図は同じくN量0.015%以上の鋼について
リジング性に及ぼすC量の影響を示した図であ
る。CはNとは逆に低い程優れており、0.015%
以下で効果が明確となり特に0.010%以下では加
工肌荒れ高さ以下のリジングになることがわかつ
た。Cの影響もまた熱延時に大圧下を加えない場
合は明確ではない。
以上示したとおり、本発明方法の効果はNが
0.015%以上、Cが0.015%以下で現われることが
わかる。
次にNb添加鋼の熱延中の再結晶挙動について
調査した結果を説明する。Nb添加鋼は1000℃以
上で1パス当り30%以上の圧下率で圧延すると熱
延中に再結晶が起り第1図および第2図に示した
とおり最終製品でのリジング性が向上することが
認められた。この場合1200℃以上では効果がある
がその程度は小さくなつた。これは、1200℃以上
では再結晶温度の高いNb添加鋼といえども歪の
回復の速度が早くなるためと推定される。さらに
1250℃を超えるともはや再結晶は起らず回復と同
時に急激な粗大化を生ずることが認められた。こ
れは、1250℃を超えるとNbの析出物の大半が固
溶するため粗大化抑制効果がなくなるためと推定
される。
次に熱延板焼鈍における再結晶について検討し
たところ、本発明においても従来提唱されている
ように(特公55−6086、特開51−149116)、900℃
以上1100℃未満にて10分以内の高温短時間焼鈍を
施すことにより延伸したフエライト粒を微細に再
結晶させることができ、リジング性改善に効果が
大きい。しかし従来はこのために低温熱延を指向
して(特開昭56−123327号公報)きたのである
が、本発明では、熱延時の再結晶を繰り返してい
るため、ことさらに低温熱延をすることなく通常
の熱延で充分にその目的を達することができる。
以上示したとおり、Nb添加フエライト系ステ
ンレス鋼においてNを添加し、1000℃以上にて高
圧下(1パス当りの圧下率30%以上60未満)を加
えることで、高温短時間の熱延板焼鈍の効果と相
俟つて、リジングを皆無にすることが可能となつ
た。しかも本発明の重要な特徴は、加熱温度にお
いても熱延の仕上げ温度においてもことさらに低
温にする必要がないという点にあり、この結果、
鋼板のロール焼付き疵を増加せしめたり熱延ロー
ルの摩耗を助長することなく、リジングを皆無に
することができるので工業的な利益は大きい。
次に本発明に用いる鋼の成分および製造条件に
ついて限定理由を述べる。
Nb添加フエライト系ステンレス鋼のCは多量
では製品の耐食性を劣化させる上、リジング性を
劣化させるため上限を0.015%とした。
Nは前述したとおりNbの窒化物としてリジン
グ改善に効果があるので0.015%以上とし、多量
になると製品の耐食性を劣化させるので上限を
0.035%とした。
Nbは再結晶温度を高くする元素であるので、
炭化物窒化物として析出する量を考慮しても鋼中
に固溶状態で存在しうるよう0.2%以上でかつC
とNの重量%の8倍以上とし、1.0%を超えると
その効果が飽和するので1.0%を上限とした。
また、Crは本発明の効果を限定する元素では
ないが、ステンレス鋼として最低限必要な10%を
下限とし、薄鋼板としての用途がない22%を上限
とした。しかし、これ以外のCr量についても本
発明の効果は現われる。なお、13%Cr鋼などは
一般にマルテンサイト系ステンレス鋼として扱わ
れているが、本発明のようにCの低い範囲では高
温にしてもオーステナイト相が現われずフエライ
ト単相であるのでフエライト系ステンレス鋼と同
じ取扱いをした。
この他耐食性の改善などを目的として1.0%以
下のCu、1.5%以下のNi、3.0%以下のMoの1種
以上を添加することもできる。
スラブの加熱温度は1250℃を超えるとNb窒化
物が固溶して粒の粗大化が起きリジング性を劣化
せしめるため1250℃を上限とした。また1100℃未
満でも1000℃以上であればリジング改善の効果は
変わらないが熱延疵を増加せしめ高温で熱延する
利益がなくなるため1100℃を下限とした。
熱延中の再結晶を起こさせるための歪の付与は
高温での大圧下であるが、圧下温度が1000℃未満
では再結晶が起こらないので1000℃を下限とし
た。圧下温度が1200℃以上では効果が小さくなる
が1250℃までは効果が認められるので圧下温度の
上限はスラブの加熱温度の上限まで有効である。
圧下率は1パス当り30%以上が必要でそれ以上
では大きい程効果がある。しかし30%未満では効
果にバラツキが生ずるため30%を下限とし、60%
以上では熱間でのロール焼付きによる激しい焼付
き疵が発生するので上限を60%未満とした。
熱延板の焼鈍は、従来の知見どおり900℃未満
では微細な再結晶が起こらないので下限とし、
1100℃以上では結晶粒の粗大化がはじまるので上
限とした。また10分を超えて焼鈍することは品質
的には効果がないので10分を上限とした。この高
温短時間焼鈍は、熱延時に再結晶を促進させた鋼
では特に効果的であつた。
次に本発明を、実施例と比較例にもとづいてさ
らに詳細に説明する。
表1に示した成分の鋼について表2に示した条
件で熱延、焼鈍し、熱延板のロール焼付き疵と最
終製品のリジング性およびr値を測定した。本発
明方法によると、熱延板の表面疵を発生させこと
なく肉眼的にはリジングがなくなり、粗さによる
測定高さも加工肌荒れ高さ以下となつて実質的
に、比較例として示したSUS304鋼の場合(No.
12)と同様リジングなしのレベルに達することが
認められる。第3図a〜dにNo.3,6,11,12の
リジング高さの測定チヤートの例を示した。また
本発明方法ではr値も高く高加工性も期待でき
る。従来指向されてきた低温熱延材(No.8)は同
じ材料の高温熱延材(No.7)に比べて優れている
ことが再現できたが、本発明方法(例えばNo.3)
に比べると、その効果は小さいことがわかる。
The present invention relates to a method for manufacturing a ferritic stainless thin steel sheet that is free from ridging and hot roll seizure flaws. Ferritic stainless thin steel sheets are less expensive than austenitic stainless steels and have a clearer color tone, so they are widely used in parts for automobiles and household appliances. However, ferritic stainless steel has the disadvantage that when it is subjected to drawing or tension processing in the manufacture of parts, an uneven striped pattern called ridging or roping occurs, which significantly impairs the appearance. A great deal of research has been conducted and various proposals have been made on methods to prevent this ridging, but the main idea is to retain as much strain as possible during hot rolling to promote recrystallization during subsequent hot-rolled sheet annealing. The purpose is to destroy the casting structure that causes ridging. Specifically, a method of hot rolling at a low temperature (see, for example, Japanese Patent Publication No. 45-34016) has been proposed, and a method of short-time annealing at a high temperature with the addition of Ti, Nb, etc. (for example, a special method of hot rolling) has been proposed. Publication No. 149116 (1972), Special Publication No. 149116 (1977)
-6086 Publication) has been proposed, and furthermore, proposals combining these methods (for example, Japanese Patent Application Laid-Open No. 1983-6086) have been proposed.
123527) has also been made. However, although these methods are effective in reducing ridging, they are not decisive for completely eliminating ridging as in the case of austenitic stainless steel. Although it is different from the above-mentioned idea, the method of once making the austenite phase appear during hot-rolled sheet annealing (Japanese Patent Publication No. 48-24611) is very effective as a measure to prevent ridging. It is necessary to perform very slow cooling or to heat for a long time below the transformation temperature, which significantly impedes productivity. Unlike the method described above, the present invention destroys the cast structure that causes ridging by repeatedly recrystallizing Nb-added ferritic single-phase stainless steel, including during hot rolling, and improves the ridging property. The aim is to completely eliminate ridging. That is, the present invention has C0.015% or less, N0.015% or more,
0.035% or less, Nb 0.2% or more, and C and N weight%
A ferritic stainless steel slab containing 8 times or more and 1.0% or less of the sum of
After hot rolling at 1000°C or higher with a reduction rate of 30% or more and less than 60% per pass at least once, heat to 1250°C or higher and at least 10 minutes at 900°C or higher and less than 1100°C. A ferrite system free from ridging and hot roll seizing defects, characterized by subjecting a hot rolled sheet to annealing, followed by cold rolling, or cold rolling with one or more intermediate annealing steps, followed by recrystallization annealing. The gist of this paper is a method for manufacturing stainless thin steel sheets. It is already known that Nb-added ferritic stainless steel has excellent ridging properties (Special Publication No. 38
However, it is well known that adding Nb alone is not decisive. The present invention takes advantage of the fact that Nb-added steel has a high recrystallization temperature, and instead of the conventional method of low-temperature hot rolling, the present invention promotes recrystallization during hot rolling by heating and hot rolling at a high temperature to prevent ridging. The feature is that it destroys the causative casting structure. In the case of steel that does not contain Nb, although the recrystallization temperature is low, hot rolling at high temperatures does not accumulate enough strain to cause recrystallization, and only recovery tends to occur, and hot rolling at low temperatures does accumulate strain, but Since recrystallization is less likely to occur during hot rolling, it is difficult to realize the features of the present invention. In steels with a high C content and in which an austenite phase appears at high temperatures, recrystallization is effective, but not to the extent that it destroys the cast structure. Next, the present inventors discovered carbides, which are Nb precipitates,
The effect of nitride was investigated. As a result, it was found that nitrides precipitated at temperatures above 1100°C, and it was assumed that these were the core of preventing crystal grain coarsening and strain accumulation. Based on this knowledge, C
and the amount of N. FIG. 1 is a diagram showing the influence of N on the ridging height of 19Cr-0.4Nb steel with carbon content of 0.01% or less.
The ● mark in the figure cannot be measured because the ridging height is less than 2 μm of the roughening height, so it is plotted uniformly at a point of 1.5 μm. The test conditions in Figure 1 are ○ and ● for slab heating at 1200℃, rolling reduction at a rolling reduction rate of 40 to 45% in the first pass of hot rolling, thickness of hot rolled sheet is 4 mm, and hot rolled sheet. The annealing was carried out at 980°C for 2 minutes, and the cold rolling was a so-called two-time cold rolling with one intermediate annealing, and the recrystallized annealed material of 0.5 mm was subjected to 20% tensile processing using a JIS No. 5 tensile test piece. The × marks are examples in which the hot rolling reduction ratio was all less than 30%. In FIG. 1, when the N content is 0.015% or more, the height of the ridging becomes less than 2μ, which is the level where no ridging occurs. Furthermore, the effect of N appears only when hot rolling is carried out under high pressure, indicating that the combined effect of both is large. FIG. 2 is a diagram showing the influence of the amount of C on the ridging properties of steels with an N amount of 0.015% or more. Contrary to N, the lower the C is, the better it is, 0.015%
It was found that the effect becomes clearer below 0.010%, and especially when the content is below 0.010%, ridging occurs below the height of roughened surface. The influence of C is also not clear unless a large reduction is applied during hot rolling. As shown above, the effect of the method of the present invention is that N
It can be seen that C appears at 0.015% or more, and C appears at 0.015% or less. Next, the results of an investigation into the recrystallization behavior during hot rolling of Nb-added steel will be explained. When Nb-added steel is rolled at a temperature of 1000°C or higher and a reduction rate of 30% or more per pass, recrystallization occurs during hot rolling, improving the ridging properties of the final product as shown in Figures 1 and 2. Admitted. In this case, there was an effect above 1200°C, but the degree of effect became smaller. This is presumed to be because the rate of strain recovery becomes faster at temperatures above 1200°C even in Nb-added steel, which has a high recrystallization temperature. moreover
It was observed that when the temperature exceeded 1250°C, recrystallization no longer occurred and rapid coarsening occurred at the same time as recovery. This is presumed to be because when the temperature exceeds 1250°C, most of the Nb precipitates dissolve into solid solution, so that the coarsening suppressing effect disappears. Next, we investigated recrystallization during hot-rolled sheet annealing and found that, as previously proposed in the present invention (Japanese Patent Publication No. 55-6086, Japanese Patent Application Publication No. 51-149116),
By performing high-temperature short-time annealing at less than 1100°C for 10 minutes or less, the stretched ferrite grains can be finely recrystallized, which is highly effective in improving ridging properties. However, conventionally, low-temperature hot rolling has been aimed at for this purpose (Japanese Unexamined Patent Publication No. 56-123327), but in the present invention, since recrystallization is repeated during hot rolling, it is possible to carry out particularly low-temperature hot rolling. Ordinary hot rolling is sufficient to achieve this purpose. As shown above, by adding N to Nb-added ferritic stainless steel and applying high pressure (reduction rate of 30% to less than 60% per pass) at 1000℃ or higher, hot-rolled sheet annealing can be performed at high temperature and for a short time. Combined with this effect, it has become possible to completely eliminate ridging. Moreover, an important feature of the present invention is that there is no need to lower the heating temperature or the hot-rolling finishing temperature to a particularly low temperature.
The industrial benefits are great because ridging can be completely eliminated without increasing roll seizure flaws on steel sheets or promoting wear of hot rolling rolls. Next, the reasons for limiting the composition and manufacturing conditions of the steel used in the present invention will be described. The upper limit of C in Nb-added ferritic stainless steel was set at 0.015% because a large amount of C deteriorates the corrosion resistance of the product as well as the ridging properties. As mentioned above, N is effective in improving ridging as a Nb nitride, so it should be set at 0.015% or more, and a large amount will deteriorate the corrosion resistance of the product, so the upper limit should be set.
It was set at 0.035%. Since Nb is an element that increases the recrystallization temperature,
Even considering the amount of precipitated carbides and nitrides, C must be at least 0.2% so that it can exist in solid solution in steel.
and at least 8 times the weight percent of N. If it exceeds 1.0%, the effect is saturated, so 1.0% is the upper limit. Furthermore, although Cr is not an element that limits the effects of the present invention, the lower limit was set at 10%, which is the minimum required for stainless steel, and the upper limit was set at 22%, which has no use as a thin steel sheet. However, the effects of the present invention can also be achieved with other amounts of Cr. Note that 13% Cr steel is generally treated as martensitic stainless steel, but as in the present invention, in a low C range, no austenite phase appears even at high temperatures and the ferrite single phase remains, so it is considered a ferritic stainless steel. was treated the same way. In addition, one or more of Cu (1.0% or less), Ni (1.5% or less), and Mo (3.0% or less) may be added for the purpose of improving corrosion resistance. The heating temperature of the slab was set at 1250°C as the upper limit because if it exceeded 1250°C, Nb nitrides would dissolve into solid solution and coarsen the grains, deteriorating the ridging properties. In addition, even if it is less than 1100°C, if it is above 1000°C, the effect of improving ridging will not change, but it will increase hot rolling defects and eliminate the benefit of hot rolling at high temperatures, so 1100°C was set as the lower limit. Strain is applied at high temperature and under large pressure to cause recrystallization during hot rolling, but recrystallization does not occur when the rolling temperature is less than 1000°C, so 1000°C was set as the lower limit. The effect decreases when the rolling temperature is 1200°C or higher, but the effect is observed up to 1250°C, so the upper limit of the rolling temperature is valid up to the upper limit of the heating temperature of the slab. The rolling reduction rate must be 30% or more per pass, and the greater the reduction rate, the more effective it is. However, if it is less than 30%, the effect will vary, so 30% is the lower limit, and 60%
In the above case, severe seizure flaws due to roll seizure occur in hot conditions, so the upper limit was set to less than 60%. As per conventional knowledge, fine recrystallization does not occur at temperatures below 900°C for annealing hot-rolled sheets, so
The upper limit was set because crystal grains begin to coarsen at temperatures above 1100°C. Furthermore, annealing for more than 10 minutes has no effect on quality, so 10 minutes was set as the upper limit. This high-temperature short-time annealing was particularly effective for steel whose recrystallization was promoted during hot rolling. Next, the present invention will be explained in more detail based on Examples and Comparative Examples. Steels having the components shown in Table 1 were hot-rolled and annealed under the conditions shown in Table 2, and the roll seizure flaws of the hot-rolled sheets, the ridging properties of the final products, and the r value were measured. According to the method of the present invention, ridging is visually eliminated without causing surface flaws on the hot-rolled sheet, and the height measured by roughness is also below the processing roughness height, which is substantially the same as that of the SUS304 steel shown as a comparative example. In the case of (No.
12), it is recognized that the level can be reached without ridging. Examples of charts for measuring the ridging heights of Nos. 3, 6, 11, and 12 are shown in FIGS. 3a to 3d. Further, the method of the present invention can be expected to have a high r value and high workability. We were able to reproduce that the conventionally oriented low-temperature hot-rolled material (No. 8) is superior to the high-temperature hot-rolled material (No. 7) of the same material, but the method of the present invention (for example, No. 3)
It can be seen that the effect is small compared to .
【表】【table】
【表】
以上詳述したように本発明方法によれば、従来
のリジング対策のように単なる軽減ではなく実質
的にリジングをなくすことになるからその取扱い
はリジングのないSUS304鋼と同様でよいことに
なる。しかも本発明方法による薄鋼板はr値も高
いことから、リジングのために加工を中断した
り、加工後の研摩に多くの労力とコストをかける
ことなく、高加工性を生かして加工に供すること
ができる。この結果、従来やむを得ず高価なNi
を多量に含むオーステナイト系ステンレス鋼(例
えばSUS304鋼)を用いていた分野で本発明方法
によるフエライト系ステンレス鋼を使用すること
が可能となるので、工業的な利益は極めて大き
い。[Table] As detailed above, according to the method of the present invention, ridging is not merely reduced as in conventional measures against ridging, but is virtually eliminated, so its handling can be the same as that of SUS304 steel without ridging. become. Moreover, since the thin steel sheet produced by the method of the present invention has a high r value, it can be processed by taking advantage of its high workability without interrupting processing for ridging or spending a lot of effort and cost on polishing after processing. I can do it. As a result, Ni
Since it becomes possible to use the ferritic stainless steel produced by the method of the present invention in fields where austenitic stainless steel (for example, SUS304 steel) containing a large amount of ferrite is used, the industrial benefits are extremely large.
第1図はリジング性に及ぼすNの影響を示す図
で、図中○印、●印は熱延1000〜1250℃の間で1
パス当り30%以上の圧下をした場合、×印はしな
い場合であり●印は肉眼上リジングが見られず、
リジング高さも加工肌荒れ高さ以下となつて測定
不可能な場合で便宜上1.5μの点にプロツトしたも
のである。第2図はリジング性に及ぼすCの影響
を示す図で、記号は第1図と同じである。第3図
は表2のNo.3、No.6、No.11およびNo.12のリジング
測定チヤートで、aはNo.3(本発明方法)、bはNo.
6(比較方法)、(c)はNo.11(比較方法、SUS430)、
(d)はNo.12(比較方法、SUS304)の測定チヤート
を示す。
Figure 1 shows the influence of N on ridging properties.
When the reduction is 30% or more per pass, the × mark indicates that there is no rolling, and the ● mark indicates that no ridging is visible to the naked eye.
The height of the ridging is also plotted at a point of 1.5μ for convenience in cases where it is impossible to measure because it is less than the height of roughened surface. FIG. 2 is a diagram showing the influence of C on ridging properties, and the symbols are the same as in FIG. 1. Figure 3 is a chart of ridging measurements of No. 3, No. 6, No. 11 and No. 12 in Table 2, where a is No. 3 (method of the present invention) and b is No. 3.
6 (comparison method), (c) is No. 11 (comparison method, SUS430),
(d) shows the measurement chart of No. 12 (comparison method, SUS304).
Claims (1)
下、Nb:0.2%以上でかつCとNの重量%の和の
8倍以上1.0%以下、Cr:10%以上22%以下を含
むフエライト系ステンレス鋼スラブを1100℃以上
1250℃以下で加熱し、1000℃以上で1パス当りの
圧下率30%以上60%未満の圧下を1回以上含んで
熱延後、900℃以上1100℃未満にて10分以内の熱
延板焼鈍を施し、しかる後冷延するかあるいは1
回以上の中間焼鈍を含んで冷延し、次いで再結晶
焼鈍を行なうことを特徴とするリジングと熱間ロ
ール焼付き疵のないフエライト系ステンレス薄鋼
板の製造方法。1 Ferrite containing C: 0.015% or less, N: 0.015% or more and 0.035% or less, Nb: 0.2% or more and 8 times or more and 1.0% or less of the sum of the weight percentages of C and N, and Cr: 10% or more and 22% or less Stainless steel slabs over 1100℃
Hot-rolled sheet heated at 1250°C or lower, including one or more reductions at 1000°C or higher with a reduction rate of 30% or more and less than 60% per pass, and then hot-rolled at 900°C or higher and less than 1100°C for 10 minutes or more. Annealing and then cold rolling or 1
A method for producing a ferritic stainless thin steel sheet free from ridging and hot roll seizure defects, characterized by cold rolling including intermediate annealing more than once, followed by recrystallization annealing.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP8228182A JPS58199822A (en) | 1982-05-15 | 1982-05-15 | Manufacture of ferritic stainless steel sheet causing no ridging |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP8228182A JPS58199822A (en) | 1982-05-15 | 1982-05-15 | Manufacture of ferritic stainless steel sheet causing no ridging |
Publications (2)
Publication Number | Publication Date |
---|---|
JPS58199822A JPS58199822A (en) | 1983-11-21 |
JPH0418013B2 true JPH0418013B2 (en) | 1992-03-26 |
Family
ID=13770122
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP8228182A Granted JPS58199822A (en) | 1982-05-15 | 1982-05-15 | Manufacture of ferritic stainless steel sheet causing no ridging |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPS58199822A (en) |
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KR100435457B1 (en) * | 1999-12-09 | 2004-06-10 | 주식회사 포스코 | A method for manufacturing ferritic stainless steel having improvable formability and ridging resistance |
EP1225242B1 (en) * | 2001-01-18 | 2004-04-07 | JFE Steel Corporation | Ferritic stainless steel sheet with excellent workability and method for making the same |
MX2018011206A (en) * | 2016-03-30 | 2018-11-22 | Nisshin Steel Co Ltd | Nb-containing ferritic stainless steel sheet and manufacturing method therefor. |
Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS5770234A (en) * | 1980-10-20 | 1982-04-30 | Nippon Steel Corp | Method of manufacture of ferritic stainless thin steel plate excellent in surface property and less in ribbing |
-
1982
- 1982-05-15 JP JP8228182A patent/JPS58199822A/en active Granted
Patent Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS5770234A (en) * | 1980-10-20 | 1982-04-30 | Nippon Steel Corp | Method of manufacture of ferritic stainless thin steel plate excellent in surface property and less in ribbing |
Also Published As
Publication number | Publication date |
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