JPH0438481B2 - - Google Patents

Description

【発明の詳細な説明】[Detailed description of the invention]

［産業上の利用分野］ 本発明は、円柱形チタン鋳塊を、鍛造を行うこ
となく分塊圧延で、スラブを製造する方法に関す
る。 ［従来の技術］ チタン材の製造には、真空アーク溶解で製造し
た、直径１ｍ以下の円柱形の鋳塊が一般的に使わ
れている。この円柱形鋳塊からスラブを製造する
場合、該鋳塊を鍛造して所定の寸法の鍛造塊と
し、これを分塊圧延してスラブとする方法が特公
昭59−16858号公報で知られ、また、円柱形鋳塊
から直接分塊圧延する方法が特開昭56−163001号
公報や特開昭59−225801号公報で知られている。
しかしながら、鍛造工程を経てスラブとする場合
には、鍛造作業の生産性を上げることが困難であ
るほか、鍛造による表面疵の発生が多く、チタン
材料のコストアツプを招く大きな原因となつい
た。一方円柱形状の鋳塊を直接分塊圧延でスラブ
にする場合は、スラブ巾の確保に問題がある。即
ち円柱形鋳塊をスラブに圧延する際、スラブ巾方
向の中央部は円柱の直径がスラブ厚さ迄圧延され
るために圧下代が最も大きく、従つて中央部が最
も長く圧延され、巾方向の両側部は中央部に追従
して延伸される傾向となる。この結果、円柱形状
鋳塊の分塊圧延では圧延巾拡がりが端部では小さ
く、したがつて圧延終了時のスラブの形状は、圧
延方向の両端部が長い舌状の形状となり、巾不測
に起因するオフゲージ切捨量が大きくなる。また
チタン材料の製造においては、鋳造技術状の制約
や、加熱時間の制約があるため、小径の円柱形の
鋳塊を使用することが多く、これから連続熱間圧
延機にて圧延するに適した巾のスラブを製造する
ために、ますます巾出しの困難さと歩留り低下の
問題を伴うものである。 ［発明が解決しようとする問題点］ 既に述べた如く、円柱形チタン鋳塊を分塊圧延
すると、圧延終了時のスラブの両端には巾が逐次
狭くなる舌状のオフゲージ部が長く発生し、切捨
除去するために分塊歩留りが低くなる。従つて本
発明の目的は、巾拡がりを大きくする分塊圧延方
法であり、更には巾狭となる舌状のオフゲージ部
の長さを短かくする。分塊圧延による円柱形チタ
ン鋳塊からスラブを製造する方法である。 ［問題点を解決するための手段］ 本発明は、円柱形チタン鋳塊を、鍛造を行うこ
となく分塊圧延で、スラブ巾が該鋳魂の直径の80
％以上でスラブ厚さが該鋳魂の直径の35％以下の
寸法のスラブを製造する方法であつて、圧延開始
温度を1100℃以下、スラブ厚さが該鋳塊の直径の
35％以下になる迄の圧延を880℃超とする圧延温
度の間で行い、かつ圧延材の厚さを減少する平パ
スと圧延材の巾を減少する立パスとを繰り返して
なる通常の圧延の平パスの圧延の中で、通常の平
パス圧延の一部に替えて圧延材の全長を圧延しな
い平パスで圧延材の終端部に末圧下の噛残し部を
形成しロールを開いて該噛残し部を通過させる圧
延パスを一回あるいは連続して複数回行う端部噛
残し圧延と続いて行う該端部噛残し圧延パスに対
して圧延方向が逆向きの平パスで噛残し部を圧延
し続いて端部噛残し圧延で圧延した部分を圧延す
る後続圧延とを組合せてなる組合せ圧延を１回以
上行うことを特徴とする円柱形チタン鋳塊からス
ラブを製造する方法である。 ［作用］ 第１図は本発明の実施の態様を示す説明図であ
り、Ａは圧延材の全長を圧延しない平パスで圧延
材の終端部に末圧下の噛残し部を形成しロールを
用いて該噛残し部を通過させる圧延パスの説明図
でイ，ロ，ハは工程順を示す。被圧延材１は圧延
ロール２，２により圧延され圧延材の厚みが減縮
されて圧延部１′となるが、この場合全長を圧延
することなく、終端部をロールに噛込んだまま残
す圧延法である。途中でロールの圧下を解放する
ことにより噛残し部１″が形成される。本発明の
端部噛残し圧延においてはこの圧延パスを一回あ
るいは連続して複数回行い、その後引き続いて後
で第１図Ｂで述べる後続圧延を行う。本発明でス
ラブ巾を鋳塊の直径の80％以上、スラブ厚さを鋳
塊の直径の35％以下としたが、現在チタン鋳塊と
して直径が600〜1000mmのものが使用されており、
これ等を用いて上記範囲の寸法のスラブを製造す
ると、広巾材の要求が強い連続熱間圧延板に対す
る現在の要望を満たすことができる。第１図Ａの
圧延パスを連続して複数回行うと、噛残し部１″
を有しかつ第１図Ａの圧延パスを一回行つた場合
よりも厚さが薄い圧延材となるが、この噛残し部
１″有しかつ厚さが薄い圧延材は巾が広いスラブ
を製造するのに好ましい。本発明では目標とする
スラブ巾にあうように、第１図Ａの圧延パスの回
数を調整する。 種々の圧延温度における巾拡がりの程度を第２
図に示す。第２図で巾拡がり率（％）は、｛（圧延
前スラブ幅−圧延後スラブ幅）／（圧延前スラブ
厚−圧延後スラブ厚）｝×100である。本発明にお
いては、圧延を880℃超で行う事としたが、純チ
タンは880℃超ではβ相にあり、熱間圧延をβ相
で行つた場合は第２図に示す如くα相やα＋β相
で圧延を行つた場合よりも巾拡がり量が大きくな
るためである。このように本発明での鋳塊からの
スラブ圧延の温度は880℃超で行う事としている
が、その圧延の際の開始温度いわゆる上限温度に
ついては、この下限温度の880℃超を確保さえで
きれば全てがβ相であるので圧延上からは何等限
定する必要はない。しかしながら、1100℃を超す
と空気からの酸素吸入が多くなつてチタンスラブ
の表層を硬化させまたはスケール発生量も多くな
り歩留りロスにつながる。従つて圧延温度の開始
温度は1100℃以下とし、加熱炉の温度も1100℃以
下に制御することが好ましい。 本発明では、通常の圧延の平パスの圧延の中
で、通常の圧延の平パスに替えて、第１図Ａの述
べた端部噛残し圧延と、その後に行う第１図Ｂの
後続圧延との組合せのパススケジユールを１回以
上行うこととしたが、これは本発明者等が実験の
結果得た知見によるものである。すなわち端部の
噛残し部が、それ以後に行う後続圧延によつて、
スラブの巾方向に押し出され、舌状オフゲージ部
分の巾方行の肉づけを行い巾方向に充填せしめる
機能を有しているからである。この作用は880℃
超の温度域において特に顕著にあらわれ、元の鋳
塊の直径の35％の厚さまで圧延する過程で有効で
ある。第３図の種々の圧延温度におけるオフゲー
ジ切捨量について示した図表である。なお第１図
Ａで示した噛残し部の長さは圧延に使用するロー
ル円周長さ1/5〜1/3程度とするのがよい。続いて
第１図Ｂに示した後続圧延を行う。後続圧延では
第１図Ｂに示した如く、端部噛残し圧延パスに対
して圧延方向が逆向きの平パスで噛残し部を圧延
し続いて端部噛残し圧延パスで圧延した部分を再
度圧延する。第１図Ｂのニ，ホはその工程順を示
す。この際ニとホは連続して１パスで行つてもよ
いし、噛残し部１″の厚さが大きい場合はニを複
数回行い。その後でニとホを連続して行つてもよ
い。 ［実施例］ 円柱形状の工業用純チタン鋳塊（サイズ：直径
720mm、長さ：2200mm）から、ロールの直径が
1000mmであるハイリフト二重分塊圧延機により厚
さ180mm、巾645mmの断面矩形状の連続熱間圧延機
用スラブを直接分塊圧延により製造した。圧下の
パススケジユールと、その場合の要所要所におけ
る圧延材の温度を第１表に示す。立パスはスラブ
の巾を形成するために巾方向に圧下し圧延材の巾
を減少する圧延であり、平パスはスラブ厚みを形
成するために厚み方向に圧下し圧延材の厚さを減
少する圧延である。端部噛残し圧延と後続圧延は
第１表の※で示したようにパスNo.５〜10で行つ
た。即ち第１表の本発明欄でパスNo.５、６、７、
８、９、10の各々は端部噛残し圧延と後続圧延パ
スとで構成されている。その場合の噛残し部分の
長さは785mmとした。尚第１表でパスNo.１〜４お
よびNo.11〜24は通常の圧延である。 このようにして得られた分塊圧延後の粗スラブ
から所定の規格を満足するように不良部分（オフ
ゲージ）を切捨てた。切捨量および最終的な歩留
りを第２表に示す。なお比較のため、従来法によ
り同一寸法の鋳塊から同一圧延機で行つた場合の [Industrial Application Field] The present invention relates to a method for producing a slab by blooming a cylindrical titanium ingot without forging. [Prior Art] In the production of titanium materials, cylindrical ingots with a diameter of 1 m or less produced by vacuum arc melting are generally used. When producing a slab from this cylindrical ingot, a method is known from Japanese Patent Publication No. 16858/1983, in which the ingot is forged into a forged ingot of predetermined dimensions, and this is then bloomed into a slab. Further, a method of direct blooming rolling from a cylindrical ingot is known from JP-A-56-163001 and JP-A-59-225801.
However, when producing a slab through the forging process, it is difficult to increase the productivity of the forging operation, and the forging often causes surface defects, which is a major cause of increasing the cost of titanium materials. On the other hand, when a cylindrical ingot is made into a slab by direct blooming rolling, there is a problem in securing the slab width. In other words, when rolling a cylindrical ingot into a slab, the center part in the width direction of the slab has the largest rolling allowance because the diameter of the cylinder is rolled to the thickness of the slab. The both sides of the sheet tend to be stretched following the central portion. As a result, in the blooming of a cylindrical ingot, the rolling width is small at the ends, and the shape of the slab at the end of rolling is a tongue-like shape with long ends in the rolling direction, which is caused by unforeseen width fluctuations. The amount of off-gauge cutoff increases. In addition, in the production of titanium materials, due to restrictions on casting technology and heating time, small-diameter cylindrical ingots are often used, making them suitable for rolling in continuous hot rolling mills. In order to manufacture wide slabs, it becomes increasingly difficult to determine the width and the problem of lower yields arises. [Problems to be Solved by the Invention] As already mentioned, when a cylindrical titanium ingot is subjected to blooming rolling, a long tongue-shaped off-gauge portion whose width gradually becomes narrower occurs at both ends of the slab at the end of rolling. The agglomeration yield will be low due to truncation and removal. Therefore, an object of the present invention is to provide a blooming method that increases the width expansion, and further shortens the length of the tongue-shaped off-gauge portion that becomes narrow. This is a method for manufacturing slabs from cylindrical titanium ingots by blooming. [Means for Solving the Problems] The present invention is a method for processing a cylindrical titanium ingot by blooming rolling without forging, so that the slab width is 80 mm the diameter of the casting soul.
% or more, the slab thickness is 35% or less of the diameter of the ingot, the rolling start temperature is 1100°C or less, and the slab thickness is less than 35% of the diameter of the ingot.
Normal rolling that involves rolling to 35% or less at a rolling temperature of over 880°C, and repeating flat passes to reduce the thickness of the rolled material and vertical passes to reduce the width of the rolled material. During flat pass rolling, in place of a part of the normal flat pass rolling, a flat pass that does not roll the entire length of the rolled material is used to form a residual part under the final rolling at the end of the rolled material, and the rolls are opened to cover the area. End portion rolling is performed by performing one or more consecutive rolling passes to pass through the leftover portion, and then the leftover portion is removed by a flat pass in which the rolling direction is opposite to the end portion rolling pass. This is a method for manufacturing a slab from a cylindrical titanium ingot, characterized by performing combination rolling one or more times, which is a combination of rolling and subsequent rolling in which the rolled portion is rolled by end part rolling. [Function] Fig. 1 is an explanatory diagram showing an embodiment of the present invention, and A shows a flat pass that does not roll the entire length of the rolled material to form a residual part under final rolling at the end of the rolled material, using rolls. In this diagram, A, B, and C indicate the order of the steps. The material to be rolled 1 is rolled by rolling rolls 2, 2, and the thickness of the rolled material is reduced to form a rolled part 1', but in this case, the rolling method is such that the end part is left bitten by the rolls without rolling the entire length. It is. A residual part 1'' is formed by releasing the rolling force of the roll midway through. In the end residual part rolling of the present invention, this rolling pass is performed once or several times in succession, and then the remaining part 1'' is formed. The subsequent rolling described in Figure 1B is carried out.In the present invention, the slab width is set to be 80% or more of the diameter of the ingot, and the slab thickness is set to be 35% or less of the diameter of the ingot, but currently titanium ingots with a diameter of 600~ 1000mm is used,
If these are used to manufacture slabs with dimensions in the above range, it is possible to meet the current demand for continuous hot-rolled sheets, which have a strong demand for wide width materials. When the rolling pass shown in Fig. 1A is performed several times in succession, the remaining part 1''
The rolled material has a thickness of 1" and is thinner than that obtained by performing the rolling pass shown in FIG. In the present invention, the number of rolling passes shown in FIG. 1A is adjusted to match the target slab width.The degree of width expansion at various rolling temperatures is
As shown in the figure. In FIG. 2, the width expansion rate (%) is {(slab width before rolling−slab width after rolling)/(slab thickness before rolling−slab thickness after rolling)}×100. In the present invention, rolling is carried out at a temperature exceeding 880°C, but pure titanium is in the β phase at temperatures above 880°C, and when hot rolling is carried out in the β phase, the α phase or α+β phase as shown in FIG. This is because the amount of width expansion becomes larger than when rolling is performed in phases. In this way, the temperature of slab rolling from an ingot in the present invention is to be carried out at a temperature exceeding 880°C, but the starting temperature during rolling, the so-called upper limit temperature, is as long as it is possible to secure the lower limit temperature of 880°C. Since everything is in the β phase, there is no need to limit it in any way from the rolling perspective. However, if the temperature exceeds 1100°C, more oxygen will be absorbed from the air, which will harden the surface layer of the titanium slab or increase the amount of scale generated, leading to yield loss. Therefore, it is preferable that the starting rolling temperature is 1100°C or lower, and the temperature of the heating furnace is also controlled to 1100°C or lower. In the present invention, in the flat pass rolling of normal rolling, in place of the flat pass of normal rolling, the end left-over rolling described in FIG. 1A and the subsequent rolling of FIG. 1B performed thereafter It was decided to perform the pass schedule in combination with the above one or more times, but this is based on the findings obtained by the inventors as a result of experiments. In other words, the unfinished portion at the end is reduced by the subsequent rolling.
This is because it has the function of being pushed out in the width direction of the slab, thickening the tongue-shaped off-gauge portion in the width direction, and filling it in the width direction. This action is 880℃
It is particularly noticeable in the super-temperature range, and is effective in the process of rolling the ingot to a thickness of 35% of the original diameter. 4 is a chart showing the amount of off-gauge cutoff at various rolling temperatures in FIG. 3. FIG. The length of the remaining portion shown in FIG. 1A is preferably about 1/5 to 1/3 of the circumferential length of the roll used for rolling. Subsequently, the subsequent rolling shown in FIG. 1B is performed. In the subsequent rolling, as shown in Fig. 1B, the remaining part is rolled with a flat pass in the opposite rolling direction to the rolling pass with no end part remaining, and then the part rolled with the end part leaving rolling pass is rolled again. Roll. D and H in FIG. 1B show the order of the steps. At this time, steps 2 and 5 may be performed successively in one pass, or if the thickness of the remaining portion 1'' is large, step 2 may be performed multiple times.After that, steps 2 and 5 may be performed continuously. [Example] A cylindrical industrial pure titanium ingot (size: diameter
720mm, length: 2200mm), roll diameter
A continuous hot rolling mill slab with a rectangular cross section of 180 mm in thickness and 645 mm in width was produced by direct blooming using a 1000 mm high-lift double blooming mill. Table 1 shows the rolling pass schedule and the temperature of the rolled material at important points in that case. Vertical pass is rolling in which the width of the rolled material is reduced by rolling in the width direction to form the width of the slab, and flat pass is rolling in the thickness direction to form the thickness of the slab to reduce the thickness of the rolled material. It is rolled. The end rolling and the subsequent rolling were performed in pass Nos. 5 to 10 as indicated by * in Table 1. That is, in the invention column of Table 1, path No. 5, 6, 7,
Each of Nos. 8, 9, and 10 is composed of end-part rolling and subsequent rolling passes. In that case, the length of the unfinished portion was 785 mm. In Table 1, passes Nos. 1 to 4 and Nos. 11 to 24 are normal rolling. Defective portions (off-gauge) were discarded from the thus obtained rough slab after blooming so as to satisfy a predetermined standard. The cutoff amount and final yield are shown in Table 2. For comparison, the results are shown below for the conventional method using the same rolling mill from an ingot of the same size.

【表】 例を第１表と第２表に付記した。【table】 Examples are added to Tables 1 and 2.

【表】 ［発明の効果］ 以上の結果から明らかなように、本発明によれ
ば切捨量は著しく減少し歩留りが大巾に向上す
る。[Table] [Effects of the Invention] As is clear from the above results, according to the present invention, the amount of truncation is significantly reduced and the yield is greatly improved.

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

第１図は本発明の実施の態様を示す説明図、第
２図は工業用純チタンの円柱形鋳塊の分塊圧延に
おける各圧延温度と巾拡がりの関係を示す図表、
第３図は同様に工業用純チタンの円柱形鋳塊を分
塊圧延した場合の分塊圧延温度とオフゲージ切捨
量の調査結果を示した図表、である。 FIG. 1 is an explanatory diagram showing an embodiment of the present invention, and FIG. 2 is a chart showing the relationship between each rolling temperature and width expansion in blooming rolling of a cylindrical ingot of industrially pure titanium.
FIG. 3 is a chart showing the investigation results of the blooming temperature and off-gauge cutting amount when a cylindrical ingot of industrially pure titanium is similarly bloomed.

Claims (1)

【特許請求の範囲】[Claims] １ 円柱形チタン鋳塊を、鍛造を行うことなく分
塊圧延で、スラブ巾が該鋳魂の直径の80％以上で
スラブ厚さが該鋳魂の直径の35％以下のスラブを
製造する方法であつて、圧延開始温度を1100℃以
下、スラブ厚さが該鋳塊の直径の35％以下になる
迄の圧延を880℃超とする間で行い、かつ圧延材
の厚さを減少する平パスと圧延材の巾を減少する
立パスとを繰り返してなる通常の圧延の平パスの
圧延の中で、通常の平パス圧延の一部に替えて圧
延材の全長を圧延しない平パスで圧延材の終端部
に末圧下の噛残し部を形成しロールを開いて該噛
残し部を通過させる圧延パスを一回あるいは連続
して複数回行う端部噛残し圧延と続いて行う該端
部噛残し圧延パスに対して圧延方向が逆向きの平
パスで噛残し部を圧延し続いて端部噛残し圧延で
圧延した部分を圧延する後続圧延とを組合せてな
る組合せ圧延を１回以上行うことを特徴とする円
柱形チタン鋳塊からスラブを製造する方法。1. A method of manufacturing a cylindrical titanium ingot by blooming rolling without forging to produce a slab with a slab width of 80% or more of the diameter of the cast soul and a slab thickness of 35% or less of the diameter of the cast soul. The rolling start temperature is 1100℃ or less, the rolling is carried out at a temperature exceeding 880℃ until the slab thickness is 35% or less of the diameter of the ingot, and flattening is performed to reduce the thickness of the rolled material. In the flat pass rolling of normal rolling, which consists of repeating passes and vertical passes that reduce the width of the rolled material, rolling with a flat pass that does not roll the entire length of the rolled material instead of a part of the normal flat pass rolling. End-left rolling is performed by forming a left-over part under final rolling at the end of the material, opening the roll, and passing through the left-over part once or several times in succession; Combination rolling is performed one or more times by rolling the remaining portion with a flat pass in which the rolling direction is opposite to the remaining rolling pass, followed by subsequent rolling in which the rolled portion is rolled with end portion rolling. A method for manufacturing a slab from a cylindrical titanium ingot, characterized by: