JPH0457401B2 - - Google Patents
Info
- Publication number
- JPH0457401B2 JPH0457401B2 JP26084884A JP26084884A JPH0457401B2 JP H0457401 B2 JPH0457401 B2 JP H0457401B2 JP 26084884 A JP26084884 A JP 26084884A JP 26084884 A JP26084884 A JP 26084884A JP H0457401 B2 JPH0457401 B2 JP H0457401B2
- Authority
- JP
- Japan
- Prior art keywords
- width
- thickness
- rolling
- continuous casting
- round billet
- 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
Links
- 238000005096 rolling process Methods 0.000 claims description 38
- 238000000034 method Methods 0.000 claims description 35
- 238000009749 continuous casting Methods 0.000 claims description 20
- 239000010935 stainless steel Substances 0.000 claims description 19
- 229910001220 stainless steel Inorganic materials 0.000 claims description 19
- 238000004519 manufacturing process Methods 0.000 claims description 13
- 238000005098 hot rolling Methods 0.000 claims description 10
- 238000012545 processing Methods 0.000 claims description 7
- 238000012360 testing method Methods 0.000 description 15
- 230000007547 defect Effects 0.000 description 11
- 239000000463 material Substances 0.000 description 7
- 230000000694 effects Effects 0.000 description 6
- 239000000203 mixture Substances 0.000 description 5
- 229910000831 Steel Inorganic materials 0.000 description 4
- 230000007797 corrosion Effects 0.000 description 4
- 238000005260 corrosion Methods 0.000 description 4
- 238000005553 drilling Methods 0.000 description 4
- 238000001192 hot extrusion Methods 0.000 description 4
- 239000010959 steel Substances 0.000 description 4
- 238000005266 casting Methods 0.000 description 2
- 229910052804 chromium Inorganic materials 0.000 description 2
- 230000002950 deficient Effects 0.000 description 2
- 230000006866 deterioration Effects 0.000 description 2
- 238000002474 experimental method Methods 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 239000000314 lubricant Substances 0.000 description 2
- 238000003754 machining Methods 0.000 description 2
- 229910052757 nitrogen Inorganic materials 0.000 description 2
- 229910052698 phosphorus Inorganic materials 0.000 description 2
- 238000005204 segregation Methods 0.000 description 2
- 239000002436 steel type Substances 0.000 description 2
- 229910052717 sulfur Inorganic materials 0.000 description 2
- 238000004364 calculation method Methods 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000005242 forging Methods 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 238000007373 indentation Methods 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 238000007670 refining Methods 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 239000007858 starting material Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000002344 surface layer Substances 0.000 description 1
- 239000000725 suspension Substances 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B23/00—Tube-rolling not restricted to methods provided for in only one of groups B21B17/00, B21B19/00, B21B21/00, e.g. combined processes planetary tube rolling, auxiliary arrangements, e.g. lubricating, special tube blanks, continuous casting combined with tube rolling
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B1/00—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations
- B21B1/46—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling metal immediately subsequent to continuous casting
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B19/00—Tube-rolling by rollers arranged outside the work and having their axes not perpendicular to the axis of the work
- B21B19/02—Tube-rolling by rollers arranged outside the work and having their axes not perpendicular to the axis of the work the axes of the rollers being arranged essentially diagonally to the axis of the work, e.g. "cross" tube-rolling ; Diescher mills, Stiefel disc piercers or Stiefel rotary piercers
- B21B19/04—Rolling basic material of solid, i.e. non-hollow, structure; Piercing, e.g. rotary piercing mills
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Metal Rolling (AREA)
- Heat Treatment Of Steel (AREA)
Description
（産業上の利用分野）
傾斜圧延方式造管加工に供するステンレス鋼管
用丸ビレツトの製造に関しこの明細書で述べる技
術内容は、連続鋳造ステンレス鋼スラブを出発材
として、上記造管加工に適合し、欠陥を含まむス
テンレス鋼管を有利かつ適切に得ることができる
工夫、つまり、上記丸ビレツトの熱間圧延に先立
つ事前のブルーム熱間加工条件の影響についての
解明を基礎とした開発研究の成果を提案するとこ
ろにある。
（従来の技術）
ステンレス鋼の丸ビレツトをブルーム連鋳材に
よつて得ることは、たとえば鉄と鋼68（1982）
S910に報じされている。
しかしブルーム連鋳材は一般に、偏析やセンタ
ーポロシテイなどの面で難点があり、とくに丸ビ
レツトへの全圧下量が比較的少いことの故に、得
られた丸ビレツトの熱間での加工性がことに傾斜
圧延方式造管加工に際して必ずしも充分とは云い
難い。
（発明が解決しようとする問題点）
継目無スレンレス鋼管は、一般に、プラグミル
方式、マンドレルミル方式などの傾斜圧延法又
は、ユージンセジユルネ方式、エアハルトプツシ
ユベンチ方式などの熱間押出し法の適用により製
造される。
ステンレス鋼は熱間加工性が悪く、傾斜圧延法
の適用のためにピアシングミルで穿孔する際に、
しばしば内面に欠陥が発生することがある。
熱間押出し法は元来熱間加工性に劣る鋼種の造
管に適合するが、この方法でビレツトの穿孔を行
う、直接穿孔では、ビレツトの長さについて、そ
の径の５〜７倍にもなると、偏肉発生が増し、そ
れ故長尺管の製造にかなりの困難を伴う。
一方予めビレツトの中央に機械加工でガイド穴
を形成しそれを押拡げる、いわゆるエキスパンジ
ヨン方式による長尺管の製法も知られているが、
この場合でもビレツトの長さがその径の約15倍程
度以下に制限される。
加えて上掲のユージン セジユルネ方式ではガ
ラス潤滑材の使用を要し、その結果圧延後におけ
る潤滑膜のはく離除去の工程を不可欠とするので
その手間とコストが加わることとなる。
上記のようなビレツト長さの制約下に、生産性
をある程度以上に高くすることができず、短いビ
レツトを使用すると歩留りも下つて、コスト的に
不利となるのは、明らかである。
とは云うものの熱間押出し法は、熱間加工性が
劣悪な鋼種であつても、重大な欠陥の発生なく造
管加工に供し得ることから、連鋳ビレツトの適用
上、さしたる支障がないことも事実である。
一方においてステンレス鋼管を傾斜圧延方式に
より造管加工することができるようになつたの
は、圧延技術の進歩、向上と、とくに素材精錬の
改善の下にＰ，Ｓ，Ｏなどの有効な低減と、
REM，Ca，Ｂなどの有利な添加の下で、ことに
分塊材に加わる鍛練効果を通した熱間加工性の改
良とに負うところが大きい。すなわち加熱温度、
熱履歴、ひずみ速度などの熱間加工性に及ぼす影
響が鋼中成分の寄与などにあわせて主に小型試験
によつて逐次に解明が進められ、その結果が実機
に応用され、最適な圧延条件が確立されるに至つ
たわけである。このようにして分塊材のビレツト
を用いる限りにおいては、傾斜圧延方式によるス
テンレス鋼管の造管加工に格別な問題はなくなつ
ている。
しかし乍らユージンセジユルネ方式の如き熱間
押出し法に連続鋳造によるビレツトが不充分なが
らも適用され得るに至つた以上は、傾斜圧延方式
においても連続鋳造材が適用され得ないと、傾斜
圧延方式造管に特有な優位性が半減するにするに
至る。
従つて傾斜圧延方式の造管加工に連続鋳造材の
とくに有利な適用を可能にすることがこの発明の
目的である。
（問題点を解決するための手段）
発明者らは、連続鋳造の製造履歴を経た材料に
よるビレツトの傾斜圧延方式造管加工への適用に
関してあまた実験と検討を重ねた結果、長、短辺
長さ比がある限度内の連続鋳造スラブの熱間圧延
を施して所定断面のブルームとし、ついでこのブ
ルームを丸ビレツトに圧延した上で、傾斜圧延方
式造管加工に供することを骨子とする手順によつ
てこの発明の成功を導くことができたものであ
る。
すなわち上掲の目的は、次の事項に則つて有利
に充足される。
すなわちこの発明は傾斜圧延方式造管加工に供
する継目無ステンレス鋼管用丸ビレツトを、Ｃ：
0.32wt％以下、Ｎ：0.4wt％以下に抑制したステ
ンレス鋼組成に成る連続鋳造スラブの幅圧下には
じまる熱間圧延によつてブルーム化する中間段階
を経てから、そのブルームに熱間圧延を施すこと
によつて調製するに当り、上記連続鋳造スラブ
は、その幅（Ｗ）が1100mm以下で、厚み（Ｔ）が
つくろうとする丸ビレツトの外径（Ｄ）に対して
少なくとも40mmは大きく、これらの幅・厚み比
（Ｗ／Ｔ）が、2.5以上、3.67以下であり、しかも
上記丸ビレツトの断面積（πD2／４）に対して少な
くとも５倍を越える断面積（Ｗ・Ｔ）を有するも
のを用いること、上記中間段階は、120〜160mm／
パスの条件での上記連続鋳造スラブの上記幅圧下
と、その後の減厚圧下も含めた熱間圧延により、
上記丸ビレツトの外径（Ｄ）に比し少なくとも30
mmは大きくかつ連続鋳造スラブの厚み（Ｔ）に対
し少なくとも10mmは小さい高さ（Ｈ）でこれに対
する幅の比（Ｂ／Ｈ）が2.0以下のブルームに加
工すること、を特徴とする、傾斜圧延方式によ
る、継目無ステンレス鋼管用丸ビレツトの製造方
法である。
ここにステンレス鋼組成というのは、Ｃ，Ｎに
ついての上掲した限定のほかにCr：11〜30wt％、
Ni：35wt％以下そしてMo：5wt％以下などを含
有することを意味するのはいうまでもない。
（作用）
ステンレス鋼組成に関しＣを0.32wt％以下に限
定するのは、強度の確保のために必要であるが、
0.32wt％をこえると、穿孔加工性が劣化するから
であり、次にＮについても強度上昇と耐食性の向
上に寄与するが、0.4wt％をこえると熱間加工性
の劣化を来して傾斜圧延方式の造管加工が困難に
なるためである。
なおCrは11wt％以上にて耐食性の向上に著し
い寄与をもたらすが30wt％をこえて含有させて
もその効果はすでに飽和に達している。Niもま
た耐食性に役立つが35wt％をこえる程の過量に
用いても効果の増進がなくコスト上不利となる。
Moは、耐孔食性に有用であるが5wt％より多
く用いてもコスト上昇を招くだけである。
次に連続鋳造スラブは、長辺の長さつまり幅Ｗ
が1100mmをこえると、スラブ厚みに拘らず長辺方
向の幅圧下によつて、幅の中央域にへこみを生じ
てブルームの形状を悪くすることによる。また連
続鋳造スラブの短辺すなわち厚みＴに対する幅Ｗ
の比Ｗ／Ｔを2.5以上、3.67以下としたのは、2.5
未満では鋳片の中心偏析度が著しくなつて中間段
階のブルーム化を経たあとにおける丸ビレツトの
穿孔加工の際に欠陥が発生しまた3.67をこえる
と、幅圧下の際に座屈を生じるようになる、限界
に当るからである。
またこの厚みＴはつくろうとする丸ビレツトの
外径Ｄに対し40mm以上大きくするのは、ブルーム
への圧延の際に十分な厚み圧下を予め加えておい
てブルームの形状を整え、ひいては丸ビレツトの
形状悪化を予防するのに必要だからである。
連続鋳造スラブの断面積Ｗ・Ｔを丸ビレツトの
断面積π／４D2の５倍以上とする必要は、この断面
積比Ｗ・Ｔ／π／４D2つまり圧下比が５に満たない
とき丸ビレツトの断面中央における熱間加工性の
充分な改善に寄与し得ずして傾斜圧延方式による
穿孔の際、管の内面に欠陥が発生するうれいがあ
ることによる。
この関係についてはＣ：0.19wt％，Si：0.4wt
％，Mn：0.6wt％，Cr：13.0wt％，Ni：0.2wt
％，Ｐ：0.02wt％，Ｓ：0.001wt％，Ｎ：0.02wt
％の成分組成になる溶鋼によつて、長辺の長さ
1100mm以内の種々な長辺長と短辺長をもつ連続鋳
造スラブをつくり、丸ビレツト径が230mm以上と
230mm以下の各場合に分け、これらの丸ビレツト
に至る圧下比が、1.2〜8.5となる圧延べ実験を行
つた結果をまとめて第１図に示すように、この圧
下比が５以上のとき、内面きずの発生が完全に鎮
静している。
次に連続鋳造スラブの幅方向に加える圧下量
を、90〜160mm／パスの範囲に変えたほかはほぼ
同様の手順で、1100mm×400mmおよび800mm×260
mmの２種の連続鋳造スラブをそれぞれ、400×350
mm、400mm×200mmのブルームに熱間圧延を行つた
ときその長辺面の中央に生じるへこみに及ぼす影
響を調べた結果を第２図に示すように、上記圧下
量を120mm／パス以上として事実上、へこみのな
い熱間圧延が可能となることがわかつた。またこ
の圧下量は160mm／パスをこえると倒れ込みによ
る不利を生じる。
ブルームの高さＨは、丸ビレツトの外径Ｄに対
し30mm以上大きくするのは、これを下まわると、
真円度の良好な丸ビレツトをつくるのが困難にな
る。またブルームの高さＨは連続鋳造スラブの厚
みＴより少なくとも10mmは小さくするのは、ブル
ームへの厚み圧下を十分に加えて、ブルームの形
状を整え、丸ビレツトの形状悪化を防ぐためであ
る。
ブルームの高さＨに対する幅Ｂの比Ｂ／Ｈは
2.0をこえるとビレツト圧延時における幅方向の
負荷が増え、倒れ込みなどの発生がある。
（実施例）
表１に化学成分を示した、試験No.１〜22の各供
試鋼をもつて種々のサイズに連続鋳造したスラブ
に熱間圧延を施してブルーム、ついで丸ビレツト
に加工した。
(Industrial Application Field) The technical content described in this specification regarding the production of round billets for stainless steel pipes to be used in inclined rolling method pipe-making processing uses continuous casting stainless steel slabs as a starting material, and is compatible with the above-mentioned pipe-making processing. We propose a method to advantageously and appropriately obtain stainless steel pipes containing defects, that is, the results of development research based on elucidation of the effects of bloom hot processing conditions prior to hot rolling of the round billet. It's there to do. (Prior art) Obtaining stainless steel round billets by continuous bloom casting is described in Tetsu-to-Hagane 68 (1982).
It is reported in S910. However, bloom continuously cast materials generally have drawbacks in terms of segregation and center porosity, and in particular, because the total reduction into the round billet is relatively small, the hot workability of the resulting round billet is poor. However, it is difficult to say that this is necessarily sufficient, especially in the case of inclined rolling method pipe forming processing. (Problems to be Solved by the Invention) Seamless stainless steel pipes are generally manufactured by applying an inclined rolling method such as a plug mill method or a mandrel mill method, or a hot extrusion method such as a Eugene Sedziurne method or an Erhardt push bench method. Manufactured by. Stainless steel has poor hot workability, and when drilling with a piercing mill for application of the inclined rolling method,
Defects often occur on the inner surface. The hot extrusion method is suitable for making pipes of steel types that inherently have poor hot workability, but with direct drilling, which uses this method to drill billets, the length of the billet can be 5 to 7 times the diameter. In this case, the occurrence of uneven thickness increases, and therefore it is quite difficult to manufacture a long tube. On the other hand, there is also a known method for manufacturing long tubes using the so-called expansion method, in which a guide hole is formed in advance by machining in the center of a billet and then expanded.
Even in this case, the length of the billet is limited to about 15 times its diameter or less. In addition, the above-mentioned Eugene Sejourne method requires the use of a glass lubricant, and as a result, a step of peeling off the lubricant film after rolling is required, which adds to the effort and cost. It is obvious that productivity cannot be increased beyond a certain level under the above-mentioned constraints on billet length, and that the use of short billets lowers the yield and is disadvantageous in terms of cost. That said, the hot extrusion method can be used to make pipes without causing serious defects even with steel types with poor hot workability, so there is no major problem when applying continuous billet casting. is also true. On the other hand, it has become possible to manufacture stainless steel pipes using the inclined rolling method due to the progress and improvement of rolling technology, and in particular, the effective reduction of P, S, O, etc. through improvements in material refining. ,
This is largely due to the improvement of hot workability through the forging effect exerted on the blooming material under the advantageous addition of REM, Ca, B, etc. In other words, the heating temperature,
The influence of thermal history, strain rate, etc. on hot workability, along with the contribution of components in the steel, has been gradually elucidated mainly through small-scale tests, and the results have been applied to actual machines to determine the optimal rolling conditions. has now been established. As long as billets of bloomed material are used in this way, there are no particular problems in forming stainless steel pipes by the inclined rolling method. However, since billets by continuous casting have come to be applied to hot extrusion methods such as the Eugene Sejourne method, although it is insufficient, continuous casting materials cannot be applied to the inclined rolling method as well. The advantages unique to method pipe manufacturing will be halved. Accordingly, it is an object of the present invention to enable particularly advantageous application of continuous casting materials to inclined rolling type tube manufacturing. (Means for Solving the Problems) As a result of repeated experiments and studies regarding the application of billets using materials that have gone through the production history of continuous casting to inclined rolling method pipe manufacturing, the inventors have determined that the long and short side lengths The process basically consists of hot rolling a continuously cast slab with a ratio within a certain limit to form a bloom of a predetermined cross section, then rolling this bloom into a round billet, and then subjecting it to inclined rolling tube manufacturing. This led to the success of this invention. In other words, the above objectives will be advantageously fulfilled in accordance with the following matters: That is, the present invention provides a round billet for seamless stainless steel pipes to be subjected to inclined rolling method pipe manufacturing processing, C:
After passing through the intermediate stage of blooming by hot rolling, which begins with width reduction of a continuously cast slab made of stainless steel with a composition of stainless steel suppressed to 0.32wt% or less and N: 0.4wt% or less, hot rolling is applied to the bloom. In preparing the continuous casting slab, the width (W) is 1100 mm or less and the thickness (T) is at least 40 mm larger than the outer diameter (D) of the round billet to be made. The width/thickness ratio (W/T) is 2.5 or more and 3.67 or less, and the cross-sectional area (W/T) is at least 5 times larger than the cross-sectional area (πD 2 /4) of the round billet. The above intermediate stage is 120~160mm/
By hot rolling including width reduction and subsequent thickness reduction of the continuous casting slab under pass conditions,
At least 30 mm compared to the outside diameter (D) of the round billet above
mm is large, the height (H) is at least 10 mm smaller than the thickness (T) of the continuous casting slab, and the width ratio (B/H) to this is 2.0 or less. This is a method for manufacturing round billets for seamless stainless steel pipes using a rolling method. Here, the stainless steel composition means that in addition to the above limitations regarding C and N, Cr: 11 to 30 wt%,
Needless to say, this means containing Ni: 35 wt% or less and Mo: 5 wt% or less. (Function) It is necessary to limit C to 0.32wt% or less in stainless steel composition to ensure strength, but
If it exceeds 0.32wt%, drilling workability deteriorates, and N also contributes to increased strength and corrosion resistance, but if it exceeds 0.4wt%, hot workability deteriorates and the slope This is because it becomes difficult to form pipes using the rolling method. Note that Cr makes a significant contribution to improving corrosion resistance at 11 wt% or more, but its effect has already reached saturation even when the content exceeds 30 wt%. Ni is also useful for corrosion resistance, but even if it is used in excess of 35 wt%, the effect will not be improved and it will be disadvantageous in terms of cost. Mo is useful for pitting corrosion resistance, but using more than 5wt% only increases cost. Next, the length of the long side of the continuous casting slab, that is, the width W
If it exceeds 1100mm, regardless of the slab thickness, the width reduction in the long side direction will cause a dent in the central area of the width, worsening the shape of the bloom. Also, the short side of the continuous casting slab, that is, the width W relative to the thickness T
The ratio W/T of 2.5 or more and 3.67 or less is 2.5
If it is less than 3.67, the degree of center segregation of the slab becomes significant and defects occur during drilling of round billets after the intermediate stage of blooming, and if it exceeds 3.67, buckling occurs during width reduction. This is because it hits the limit. In addition, the reason why this thickness T is made 40 mm or more larger than the outside diameter D of the round billet to be made is to apply sufficient thickness reduction in advance when rolling into a bloom to adjust the shape of the bloom, and thus to improve the shape of the round billet. This is because it is necessary to prevent shape deterioration. It is necessary to make the cross-sectional area W・T of the continuous casting slab at least 5 times the cross-sectional area π/4D 2 of the round billet. This is because the hot workability at the center of the cross section of the billet cannot be sufficiently improved, and defects may occur on the inner surface of the tube during perforation by the inclined rolling method. Regarding this relationship, C: 0.19wt%, Si: 0.4wt
%, Mn: 0.6wt%, Cr: 13.0wt%, Ni: 0.2wt
%, P: 0.02wt%, S: 0.001wt%, N: 0.02wt
Depending on the molten steel with a composition of %, the length of the long side
Continuously cast slabs with various long side lengths and short side lengths within 1100 mm are made, and the round billet diameter is 230 mm or more.
Figure 1 summarizes the results of rolling experiments in which the rolling reduction ratio leading to these round billets ranges from 1.2 to 8.5 in each case of 230 mm or less.When the rolling reduction ratio is 5 or more, The occurrence of internal scratches has completely subsided. Next, the same procedure was followed except that the reduction applied in the width direction of the continuous casting slab was changed to a range of 90 to 160 mm/pass.
Two types of continuous casting slabs of 400 x 350 mm each
Figure 2 shows the results of investigating the effect on the indentation that occurs in the center of the long side surface when hot rolling a bloom of 400 mm x 200 mm. It was found that hot rolling without dents was possible. Moreover, if the amount of reduction exceeds 160 mm/pass, there will be a disadvantage due to collapse. The height H of the bloom should be increased by 30 mm or more compared to the outside diameter D of the round billet, and if it is less than this,
It becomes difficult to make round billets with good roundness. The height H of the bloom is made at least 10 mm smaller than the thickness T of the continuous casting slab in order to sufficiently reduce the thickness of the bloom, adjust the shape of the bloom, and prevent deterioration of the shape of the round billet. The ratio B/H of the width B to the height H of the bloom is
If it exceeds 2.0, the load in the width direction during billet rolling will increase and collapse may occur. (Example) Slabs were continuously cast into various sizes using test steels of test Nos. 1 to 22 whose chemical compositions are shown in Table 1, and were hot rolled to form blooms and then round billets. .
【表】【table】
【表】
ここにブルーム圧延並びにビレツト圧延のため
の加熱温度は何れも1250℃とし、表層部と中央部
とにおける温度差が10℃以下になる在炉時間を伝
熱計算によつて求め、均熱保持をしてから圧延に
供し、これら各圧延におけるひずみ速度について
は１〜５／ｓである。
この発明に従う試験No.１〜８の適合例にあつて
は、ブルーム圧延および丸ビレツト圧延を経たの
ちの傾斜圧延方式造管法の適用で何ら欠陥発生は
見られなかつた。
これに反して試験No.９はＣが、また同No.10はＮ
が、何れも上限をこえていた成分不適合により管
内面欠陥を生じた。
また試験No.11と15は、連鋳スラブの幅Ｗが過大
なためブルームの長辺中央に著しいへこみができ
る形状不良のため丸ビレツトへの圧延を断念し
た。
次に試験No.12，17およびに20については、丸ビ
レツト外径に対するブルーム高さの関係条件を満
たさぬため、真円度不良となつた。次に試験No.13
は、連続鋳造スラブの幅圧下１パス当りの最低圧
下量が下限を下まわるためブルームの長辺中央に
へこみを来す形状不良のため、以降の圧延を中止
した。
次に試験No.14，18は連続鋳造スラブの幅、厚み
比Ｗ／Ｔが小さすぎるため、圧下比は大きいにも
拘らず、管内面欠陥が発生している。なおこの場
合は、試験番号５および７について示した適合例
の連続鋳造スラブにおいて、それぞれ片側270mm、
100mm宛を両側で切断除去して狭幅とした場合に
不適合となる事例を示した。
次に試験No.16と19はブルームの高さＨが、連続
鋳造スラブの厚みＴに等しいので厚み方向での圧
下が不充分であり、その故、ブルームの長辺面中
央のへこみによる形状不良で圧延中断となつた不
適合例である。
なお試験No.12については丸ビレツトの外径を
300mmに施削加工してみかけ上試験No.４と揃えた
上で傾斜圧延方式造管に供したが、丸ビレツトま
での圧下が充分に加わつていないため管内面欠陥
が不可避であつた。これに反し試験No.20につき、
丸ビレツトの外径を240mmから220mmに施削加工し
て真円度不良を矯正した上で造管加工を行つたと
ころ、丸ビレツトに至る圧下比が6.33で充分なた
め、欠陥のない造管が可能であつた。
ここに真円度は互いに直交する最大直径は最小
直径の差であらわし１mmをこえる場合は不適合で
あつた。
（発明の効果）
この発明によれば連続鋳造ステンレス鋼スラブ
を素材として、傾斜圧延方式造管加工による継目
無スレンレス鋼管を、長尺の丸ビレツトによつて
欠陥なく、しかも能率的に製造可能とし、歩留り
向上と生産性の改善を通して、この種鋼管のコス
ト切下げが実現される。[Table] Here, the heating temperature for both bloom rolling and billet rolling is 1250°C, and the furnace time during which the temperature difference between the surface layer and the center part is 10°C or less is determined by heat transfer calculation, and the After heat retention, it is subjected to rolling, and the strain rate in each rolling is 1 to 5/s. In the conforming examples of Test Nos. 1 to 8 according to the present invention, no defects were observed when the inclined rolling method was applied after bloom rolling and round billet rolling. On the other hand, test No. 9 was C, and test No. 10 was N.
However, in both cases, defects occurred on the inner surface of the tube due to component incompatibility that exceeded the upper limit. Further, in Test Nos. 11 and 15, rolling into a round billet was abandoned due to poor shape with a significant dent in the center of the long side of the bloom due to the excessive width W of the continuously cast slab. Next, in Test Nos. 12, 17, and 20, the roundness was poor because the relationship condition of the bloom height to the outside diameter of the round billet was not satisfied. Next test No.13
Because the minimum width reduction per pass of the continuously cast slab was below the lower limit, the bloom was defective in shape with a dent in the center of the long side, so subsequent rolling was discontinued. Next, in Test Nos. 14 and 18, the width and thickness ratio W/T of the continuously cast slabs were too small, so defects occurred on the inner surface of the tube despite the large reduction ratio. In this case, in the continuous casting slab of the compatible example shown for test numbers 5 and 7, each side is 270 mm,
We have shown an example of non-conformity when a 100mm piece is cut and removed on both sides to make it narrower. Next, in Test Nos. 16 and 19, the height H of the bloom was equal to the thickness T of the continuous casting slab, so the reduction in the thickness direction was insufficient, and therefore the shape was defective due to the depression in the center of the long side of the bloom. This is an example of a nonconformity that resulted in the suspension of rolling. For test No. 12, the outer diameter of the round billet is
After machining to 300 mm to make the appearance similar to test No. 4, it was subjected to inclined rolling tube making, but defects on the inner surface of the tube were unavoidable because sufficient reduction to the round billet was not applied. On the contrary, regarding test No. 20,
When the outside diameter of the round billet was machined from 240 mm to 220 mm to correct the roundness defects and then pipe-formed, the reduction ratio to form a round billet was 6.33, which was sufficient, resulting in a defect-free pipe. was possible. Here, roundness is expressed as the difference between the maximum diameter and the minimum diameter, which are perpendicular to each other, and if it exceeds 1 mm, it is considered unsuitable. (Effects of the Invention) According to the present invention, it is possible to efficiently manufacture seamless stainless steel pipes using continuous cast stainless steel slabs by tilt rolling method pipe forming process without defects using long round billets. , the cost of this type of steel pipe can be reduced through improved yield and productivity.
第１図は連鋳スラブからビレツトへの圧下比が
内面きず発生率に及ぼす影響を示すグラフ、第２
図は１パスの圧下量が、ブルームの長辺中央にお
けるへこみの発生に及ぼす影響を示すグラフであ
る。
Figure 1 is a graph showing the influence of the rolling reduction ratio from a continuously cast slab to a billet on the internal flaw occurrence rate.
The figure is a graph showing the influence of the amount of reduction in one pass on the occurrence of a dent in the center of the long side of the bloom.
Claims (1)
レス鋼管用丸ビレツトを、Ｃ：0.32wt％以下、
Ｎ：0.4wt％以下に抑制したステンレス鋼組成に
成る連続鋳造スラブの幅圧下にはじまる熱間圧延
によつてブルーム化する中間段階を経てから、そ
のブルームに熱間圧延を施すことによつて調製す
るに当り、 上記連続鋳造スラブは、その幅（Ｗ）が1100mm
以下で、厚み（Ｔ）がつくろうとする丸ビレツト
の外径（Ｄ）に対して少なくとも40mmは大きく、
これらの幅・厚み比（Ｗ／Ｔ）が、2.5以上、
3.67以下であり、しかも上記丸ビレツトの断面積
（πD2／４）に対して少なくとも５倍を越える断面積 （Ｗ・Ｔ）を有するものを用いること、 上記中間段階は、120〜160mm／パスの条件での
上記連続鋳造スラブの上記幅圧下と、その後の減
厚圧下も含めた熱間圧延により、上記丸ビレツト
の外径（Ｄ）に比し少なくとも30mmは大きくかつ
連続鋳造スラブの厚み（Ｔ）に対し少なくとも10
mmは小さい高さ（Ｈ）でこれに対する幅の比
（Ｂ／Ｈ）が2.0以下のブルームに加工すること、 を特徴とする、傾斜圧延方式による、継目無ステ
ンレス鋼管用丸ビレツトの製造方法。[Scope of Claims] 1. A round billet for seamless stainless steel pipes to be subjected to inclined rolling method pipe-making processing, C: 0.32 wt% or less,
Prepared by hot rolling the bloom after going through an intermediate stage of blooming by hot rolling starting with width reduction of a continuously cast slab made of stainless steel with N: 0.4wt% or less. In doing so, the width (W) of the above continuous casting slab is 1100 mm.
In the following, the thickness (T) is at least 40 mm larger than the outer diameter (D) of the round billet to be made.
The width/thickness ratio (W/T) of these is 2.5 or more,
3.67 or less, and which has a cross-sectional area (W・T) that is at least 5 times larger than the cross-sectional area (πD 2 /4) of the above round billet. As a result of the above-mentioned width reduction and subsequent hot rolling including thickness reduction of the above-mentioned continuous casting slab under the following conditions, the continuous casting slab has a thickness that is at least 30 mm larger than the outer diameter (D) of the above-mentioned round billet and a thickness of the continuous casting slab ( T) at least 10
A method for producing a seamless round billet for stainless steel pipe using an inclined rolling method, characterized by processing the billet into a bloom having a small height (H) in mm and a width to width ratio (B/H) of 2.0 or less.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP26084884A JPS61140301A (en) | 1984-12-12 | 1984-12-12 | Manufacture of round billet for seamless stainless steel pipe by skew rolling |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP26084884A JPS61140301A (en) | 1984-12-12 | 1984-12-12 | Manufacture of round billet for seamless stainless steel pipe by skew rolling |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS61140301A JPS61140301A (en) | 1986-06-27 |
| JPH0457401B2 true JPH0457401B2 (en) | 1992-09-11 |
Family
ID=17353591
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP26084884A Granted JPS61140301A (en) | 1984-12-12 | 1984-12-12 | Manufacture of round billet for seamless stainless steel pipe by skew rolling |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS61140301A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2012152804A (en) * | 2011-01-27 | 2012-08-16 | Sumitomo Metal Ind Ltd | Method for manufacturing seamless steel pipe in high alloy or stainless steel |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH057990A (en) * | 1990-10-08 | 1993-01-19 | Kawasaki Steel Corp | Manufacture of round billet for seamless steel pipe |
| JP4556861B2 (en) * | 2005-12-15 | 2010-10-06 | 住友金属工業株式会社 | Round billet manufacturing method |
| US9468959B2 (en) | 2010-12-22 | 2016-10-18 | Nippon Steel & Sumitomo Metal Corporation | Production method of seamless tube using round bar made of high Cr-high Ni alloy |
-
1984
- 1984-12-12 JP JP26084884A patent/JPS61140301A/en active Granted
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2012152804A (en) * | 2011-01-27 | 2012-08-16 | Sumitomo Metal Ind Ltd | Method for manufacturing seamless steel pipe in high alloy or stainless steel |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS61140301A (en) | 1986-06-27 |
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