JPH07316683A - Blank for rolling titanium-aluminum alloy and its production - Google Patents
Blank for rolling titanium-aluminum alloy and its productionInfo
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- JPH07316683A JPH07316683A JP11118294A JP11118294A JPH07316683A JP H07316683 A JPH07316683 A JP H07316683A JP 11118294 A JP11118294 A JP 11118294A JP 11118294 A JP11118294 A JP 11118294A JP H07316683 A JPH07316683 A JP H07316683A
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- tial
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Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、TiAl系合金圧延用素材
及びその製造方法に関し、詳細には、主要成分としてTi
及びAlを含有し、金属間化合物TiAlを主要構成相とする
TiAl系合金よりなり、圧延用素材として使用されるTiAl
系合金圧延用素材及びその製造方法に関し、特には航空
機用等の軽量高機能材料として好適なTiAl系合金薄板の
圧延用素材及びその製造方法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a TiAl alloy rolling material and its manufacturing method.
And Al, with the intermetallic compound TiAl as the main constituent phase
TiAl made of TiAl alloy and used as a material for rolling
TECHNICAL FIELD The present invention relates to a material for rolling a system-based alloy and a method for manufacturing the same, and particularly to a material for rolling a TiAl-based alloy thin plate suitable for a lightweight and high-performance material for aircraft and a method for manufacturing the same.
【０００２】[0002]
【従来の技術】航空機、自動車、化学プラント、工具等
の各産業分野において、エンジン効率の向上、耐用年数
の延長、コスト低減等の要求が益々強くなってきてい
る。そのため、更に強度、弾性率、耐熱性、耐食性等に
優れた高性能及び高機能の材料が強く要望されている。
かかる高性能高機能材料としては、金属間化合物NiAl、
FeAl、又は、TiAl等を主要構成相とするNi-Al 系合金、
Fe-Al 系合金、Ti-Al 系合金（TiAl系合金）等が挙げら
れ、この中でもTiAl系合金は軽量高弾性率、高比強度、
高耐熱性等に優れていることから、各産業分野において
注目を集めている。2. Description of the Related Art In the industrial fields of aircraft, automobiles, chemical plants, tools, etc., there are increasing demands for improved engine efficiency, extended service life, and reduced costs. Therefore, there is a strong demand for high-performance and high-performance materials that are further excellent in strength, elastic modulus, heat resistance, corrosion resistance and the like.
As such a high performance and high performance material, intermetallic compound NiAl,
Ni-Al based alloys with FeAl or TiAl as the main constituent phase,
Fe-Al-based alloys, Ti-Al-based alloys (TiAl-based alloys), etc. are mentioned. Among them, TiAl-based alloys are lightweight, high elastic modulus, high specific strength,
It is attracting attention in various industrial fields due to its excellent heat resistance.
【０００３】かかるTiAl系合金の圧延用素材は、主要成
分としてTi及びAlを含有するTiAl系合金溶湯を、板状キ
ャビティを有する鋳型に注湯して凝固をさせる方法によ
り製造される。このとき、鋳型として黒鉛鋳型やCu鋳型
等の如く、熱伝導率の高い材質で構成した鋳型（即ち冷
却構造の鋳型）が使用される。これは、鋳型材料と溶湯
との反応による汚染を防止するためである。即ち、TiAl
系合金の機械的特性は不純物、組織形態等によって大き
く影響を受けるので、これら不純物、組織形態等につい
ては充分な注意が必要となり、特に、TiAl系合金の主要
構成元素がTi、Alであって非常に活性であることから、
溶解・鋳造に際して不純物汚染を極力抑制する必要があ
り、又、成分偏析や鋳造欠陥のない均質なものとする必
要があるが、この中の鋳造の際の不純物汚染を極力抑制
するため、鋳型材料と溶湯との反応が起こり難い冷却構
造の鋳型が使用される。A material for rolling such a TiAl alloy is manufactured by a method of pouring a molten TiAl alloy containing Ti and Al as main components into a mold having a plate-shaped cavity to solidify it. At this time, a mold made of a material having a high thermal conductivity (that is, a mold having a cooling structure) such as a graphite mold or a Cu mold is used as the mold. This is to prevent contamination due to the reaction between the mold material and the molten metal. That is, TiAl
Since the mechanical properties of the system alloys are greatly affected by impurities, microstructures, etc., it is necessary to pay sufficient attention to these impurities, microstructures, etc., especially when the main constituent elements of the TiAl system alloy are Ti and Al. Because it is very active,
It is necessary to suppress impurity contamination during melting and casting as much as possible, and it is also necessary to make it homogeneous without component segregation and casting defects. In order to suppress impurity contamination during casting as much as possible, mold material A mold having a cooling structure in which the reaction between the molten metal and the molten metal hardly occurs is used.
【０００４】TiAl系合金溶湯を得るための溶解法として
は、コールドクルーシブル誘導溶解炉による溶解法の採
用が推奨されている。これは、上記溶解の際の不純物汚
染を極力抑制すると共に成分偏析のない均質なものとす
るためである。即ち、従来一部の低品位のTi合金におい
て採用されているカルシアるつぼによる真空溶解では、
酸素の汚染が不可避であり、又、真空アーク溶解では、
溶湯プールが小さいことにより成分偏析が生じ、いづれ
もTiAl系合金の場合には問題となるので、雰囲気を制御
したチャンバー内で無汚染且つ均質溶解が可能なコール
ドクルーシブル誘導溶解炉（誘導スカル溶解炉）による
溶解法が推奨される。As a melting method for obtaining a molten TiAl alloy, it is recommended to adopt a melting method using a cold crucible induction melting furnace. This is to suppress the impurity contamination during the dissolution as much as possible and to make the material homogeneous without segregation of components. That is, in the vacuum melting by the calcia crucible conventionally used in some low-grade Ti alloys,
Oxygen contamination is unavoidable, and in vacuum arc melting,
Since the segregation of components occurs due to the small pool of molten metal, which is a problem in any case of TiAl-based alloys, a cold crucible induction melting furnace (induction skull melting furnace) capable of non-contaminating and homogeneous melting in a chamber with controlled atmosphere ) Is recommended.
【０００５】ここで、コールドクルーシブル誘導溶解炉
による溶解法は、水冷銅るつぼ内にTiAl系合金のスカル
（凝固殻）を形成しつつ、高周波溶解を行う方式のもの
であり、溶湯はそれ自身の凝固殻内で保持され、更に高
周波溶解のため溶湯プールも深くなるので、無汚染で且
つ均質な溶解が可能となる。Here, the melting method using a cold crucible induction melting furnace is a method of performing high frequency melting while forming a skull (solidified shell) of a TiAl alloy in a water-cooled copper crucible, and the molten metal is its own. It is held in the solidified shell, and since the molten metal pool is deepened due to the high frequency melting, it is possible to achieve a uniform pollution-free melting.
【０００６】[0006]
【発明が解決しようとする課題】ところが、このような
従来のTiAl系合金圧延用素材の製造方法においては、得
られる圧延用素材は鋳造欠陥が多く、又、難加工性であ
って熱間圧延が極めてし難く、引いては、良好なTiAl系
合金板が得られ難いという問題点がある。However, in such a conventional method for producing a material for rolling a TiAl-based alloy, the material for rolling obtained has many casting defects and is difficult to work because it is difficult to hot roll. However, there is a problem that it is difficult to obtain a good TiAl alloy plate.
【０００７】即ち、溶解法としてコールドクルーシブル
誘導溶解炉による溶解法が採用されるが、本溶解法も唯
一の原理上の欠点としてスーパーヒート（ΔＴ：液相線
温度と溶湯温度との差）が大きくとれないという問題点
があり、TiAl系合金の場合で高々40℃程度しか実現され
ていない。溶融金属の粘性は温度依存性が大きく、スー
パーヒートが小さいと粘性が大きくなり、鋳型への充填
性、湯流れ性が著しく低下する。従って、鋳造欠陥が発
生し易くなり、特に、表面積／体積（表面積と体積との
比）が大きくて鋳造の困難な形状である板状の圧延用素
材（例えば厚さ１〜４mmの薄板状圧延用素材）の鋳造の
場合は、溶湯の未充填部や最終凝固部である板中心部
に、引け巣、ガス等の鋳造欠陥が数多く発生するという
問題点がある。これらの欠陥は圧延用素材の圧延の際に
割れの起点になったり、圧延後もそのまま残存したりす
る。That is, a melting method using a cold crucible induction melting furnace is adopted as the melting method. However, this melting method has the only principle drawback that is superheat (ΔT: difference between liquidus temperature and molten metal temperature). There is a problem that it cannot be taken large, and in the case of TiAl-based alloys, it has been realized only at about 40 ° C at most. The viscosity of the molten metal has a large temperature dependency, and when the superheat is small, the viscosity becomes large, and the mold filling property and the molten metal flowability are significantly reduced. Therefore, casting defects are likely to occur, and particularly, a plate-shaped rolling material having a large surface area / volume (ratio of surface area to volume) and difficult to cast (for example, a thin plate-shaped rolling having a thickness of 1 to 4 mm). In the case of the casting of the material), there is a problem that a large number of casting defects such as shrinkage cavities and gas occur in the center portion of the plate which is the unfilled portion of the molten metal or the final solidified portion. These defects become the starting points of cracks during rolling of the material for rolling, or remain as they are after rolling.
【０００８】また、鋳造の際の凝固時にTiAl系合金特有
のラメラー組織（α2:Ti3Al とγ：TiAlとの層状組織）
が形成され、このラメラー組織が硬く、脆く、変形能に
乏しく、更に異方性を有しているため、難加工性であ
り、高温でも圧延時の変形抵抗が大きく、又、割れ等が
発生し易く、非常に圧延が困難であるという問題点があ
る。Further, a lamellar structure peculiar to a TiAl alloy during solidification during casting (a layered structure of α 2 : Ti 3 Al and γ: TiAl)
Is formed, and this lamellar structure is hard, brittle, poor in deformability, and has anisotropy, so it is difficult to work, and the deformation resistance during rolling is large even at high temperatures, and cracks etc. occur. However, there is a problem that rolling is very difficult and rolling is very difficult.
【０００９】本発明はこの様な事情に着目してなされた
ものであって、その目的は、前記従来のものが有する問
題点を解消し、鋳造欠陥が少なく、且つ、加工性に優れ
て熱間圧延を容易にし得るTiAl系合金圧延用素材及びそ
の製造方法を提供しようとするものである。The present invention has been made by paying attention to such a situation, and an object thereof is to solve the problems of the above-mentioned conventional ones, to reduce casting defects and to improve workability. It is intended to provide a material for rolling a TiAl-based alloy capable of facilitating hot rolling and a method for producing the same.
【００１０】[0010]
【課題を解決するための手段】上記の目的を達成するた
めに、本発明に係るTiAl系合金圧延用素材及びその製造
方法は、次のような構成としている。即ち、請求項１記
載のTiAl系合金圧延用素材の製造方法は、主要成分とし
てTi及びAlを含有するTiAl系合金溶湯を、板状キャビテ
ィを有し、板厚方向に対して片側断熱、片側冷却構造の
鋳型に注湯して指向性凝固をさせることにより板状に鋳
造することを特徴とするTiAl系合金圧延用素材の製造方
法である。In order to achieve the above object, the material for rolling a TiAl alloy and the method for producing the same according to the present invention have the following configurations. That is, the method for manufacturing a material for rolling a TiAl alloy according to claim 1 has a TiAl alloy molten metal containing Ti and Al as main components, has a plate-shaped cavity, and is heat-insulated on one side in the thickness direction and on one side. A method for producing a material for rolling a TiAl-based alloy, which comprises casting the material into a plate by pouring the molten metal into a mold having a cooling structure to cause directional solidification.
【００１１】請求項２記載のTiAl系合金圧延用素材の製
造方法は、前記TiAl系合金溶湯中のAl量が30〜50at％で
ある請求項１記載のTiAl系合金圧延用素材の製造方法で
ある。請求項３記載のTiAl系合金圧延用素材の製造方法
は、前記鋳造の際の雰囲気として真空又は不活性雰囲気
が適用される請求項１又は２記載のTiAl系合金圧延用素
材の製造方法である。The method for manufacturing a TiAl alloy rolling material according to claim 2 is the method for manufacturing a TiAl alloy rolling material according to claim 1, wherein the amount of Al in the molten TiAl alloy is 30 to 50 at%. is there. The method for producing a TiAl alloy rolling material according to claim 3 is the method for producing a TiAl alloy rolling material according to claim 1 or 2, wherein a vacuum or an inert atmosphere is applied as an atmosphere during the casting. .
【００１２】請求項４記載のTiAl系合金圧延用素材は、
板厚方向に指向性凝固された板状のTiAl系合金よりな
り、該合金の層状組織の長手方向と板厚方向とのなす角
度が30〜60°であることを特徴とするTiAl系合金圧延用
素材である。The material for rolling a TiAl alloy according to claim 4 is:
TiAl-based alloy rolling characterized by comprising a plate-shaped TiAl-based alloy directionally solidified in the plate-thickness direction, and the angle between the longitudinal direction of the layered structure of the alloy and the plate-thickness direction is 30 to 60 °. It is a material.
【００１３】[0013]
【作用】本発明は、前記目的を達成するため鋭意研究を
重ねた結果、板状キャビティを有し、板厚方向に対して
片側断熱、片側冷却構造の鋳型にTiAl系合金溶湯を注湯
して指向性凝固をさせることにより板状に鋳造する方法
により、鋳造欠陥が少なく、且つ、加工性に優れて熱間
圧延を容易にし得るTiAl系合金圧延用素材を製造できる
という知見を得、かかる知見に基づき完成されたもので
ある。The present invention has conducted extensive studies in order to achieve the above-mentioned object, and as a result, has a plate-shaped cavity and injects a molten TiAl-based alloy into a mold having one-sided heat insulation and one-sided cooling structure in the plate thickness direction. By the method of casting in a plate shape by directional solidification, there is little casting defect, and obtained the knowledge that it is possible to manufacture a TiAl alloy rolling material that has excellent workability and can facilitate hot rolling. It was completed based on knowledge.
【００１４】即ち、板状キャビティを有し、板厚方向に
対して片側断熱、片側冷却構造の鋳型にTiAl系合金の溶
湯を注湯して鋳型の冷却側から断熱側に指向性をもたせ
て凝固させる指向性凝固法によれば、鋳造欠陥が少な
く、且つ、加工性に優れて熱間圧延を容易にし得る板状
鋳片（TiAl系合金圧延用素材）が得られることが判明し
た。このように特性の優れたTiAl系合金圧延用素材が指
向性凝固法により得られる理由を以下説明する。That is, a molten TiAl alloy is poured into a mold having a plate-shaped cavity and one-sided heat insulation and one-sided cooling structure in the plate thickness direction so that the cooling side of the mold has a directivity toward the heat insulation side. It has been found that the directional solidification method of solidifying can provide a plate-shaped cast piece (material for TiAl-based alloy rolling) that has few casting defects, is excellent in workability, and can facilitate hot rolling. The reason why the TiAl alloy rolling material having such excellent properties can be obtained by the directional solidification method will be described below.
【００１５】TiAl系合金は溶湯の凝固時にβTiが初晶と
して晶出し、状態図からも判るように、以下のように凝
固が進行する。 Ｌ→〔β〕＋Ｌ→〔β＋α〕＋Ｌ→〔β＋α〕＋γB →
〔α〕＋γB→〔α＋γ〕＋γB →〔α2 ＋γ〕＋γB （ここで、γB :interdendritic γ-segregate） 即ち、初晶としてβが晶出し、包晶反応でαが晶出し、
その後、固相反応が進む。ここで、初晶βは bccである
ので、＜１００＞が最大結晶成長速度を有し、（１０
０）面を柱面とする柱状晶となり、その先端は原子密度
の最も高い、換言すれば、表面張力最小の（１１０）面
を錐面とする。この周囲に晶出するαは、hcp であるた
め、下記に示す方位関係から、前記錐面にαの｛０００
１｝面が平行となる形で晶出する。更に、これらが全て
αになり、このαから hcpのα2 とfcc のγが下記方位
関係をもって変態する。これがTiAl系合金特有のラメラ
ー組織（α2:Ti3Al とγ：TiAlとの層状組織）である。
従って、このラメラー方向はデンドライトの優先成長方
向＜１００＞に対して45°の角度を有する。故に、ラメ
ラー組織は、そのラメラー方向が凝固進行方向に対して
45°の角度をもって形成される。 ｛１１０｝β／／｛０００１｝α／／｛１１１｝γIn the TiAl-based alloy, βTi crystallizes as a primary crystal during solidification of the molten metal, and solidification proceeds as follows, as can be seen from the phase diagram. L → [β] + L → [β + α] + L → [β + α] + γ B →
[Α] + γ B → [α + γ] + γ B → [α 2 + γ] + γ B (here, γ B : interdendritic γ-segregate) That is, β crystallizes as a primary crystal and α crystallizes in the peritectic reaction,
Then, the solid phase reaction proceeds. Here, since the primary crystal β is bcc, <100> has the maximum crystal growth rate, and (10
It becomes a columnar crystal having a (0) plane as a columnar surface, and its tip has a highest atomic density, in other words, a (110) plane having a minimum surface tension is a conical surface. Since α crystallized around this is hcp, from the orientational relation shown below, α of {000
Crystallization occurs with the 1} planes being parallel. Further, all of them become α, and α 2 of hcp and γ of fcc are transformed from this α with the following orientation relationship. This is the lamellar structure (layered structure of α 2 : Ti 3 Al and γ: TiAl) peculiar to TiAl alloy.
Therefore, this lamellar direction has an angle of 45 ° with respect to the dendrite preferential growth direction <100>. Therefore, in the lamellar structure, the lamellar direction is
It is formed with an angle of 45 °. {110} β // {0001} α // {111} γ
【００１６】従って、板厚方向に指向性凝固させれば、
ラメラー組織は板厚方向（即ち圧延加工の際に圧延荷重
がかかる方向）に対して45°の角度を持って形成され
る。そうすると、圧延加工の際に剪断変形が層境界に沿
って起こり（例えば、Philos.Mag. A, 61(1990), 591
）、そのため変形が容易になり、圧延加工性が向上す
るはずである。指向性凝固法は、かかる指向性凝固が可
能であり、故に圧延加工性を向上させ得る。以上が、指
向性凝固法によれば、加工性に優れて熱間圧延を容易に
し得るTiAl系合金圧延用素材が得られる理由である。Therefore, if directional solidification is performed in the plate thickness direction,
The lamellar structure is formed at an angle of 45 ° with respect to the plate thickness direction (that is, the direction in which the rolling load is applied during rolling). Then, shear deformation occurs along the layer boundary during rolling (for example, Philos. Mag. A, 61 (1990), 591).
), Therefore, deformation should be facilitated and rolling workability should be improved. The directional solidification method is capable of such directional solidification and therefore can improve the rolling workability. The above is the reason why the directional solidification method makes it possible to obtain a TiAl alloy rolling material that is excellent in workability and can facilitate hot rolling.
【００１７】ここで、指向性凝固法によれば板厚方向へ
の指向性凝固が可能であるのは、指向性凝固法によれ
ば、板厚方向に対して片側断熱、片側冷却構造の鋳型に
溶湯が注湯されることに起因し、熱流は断熱側から冷却
側に向かうので、鋳型面で多様な方位を持つ初晶が晶出
しても、熱流に対して最適な成長方向を有する結晶のみ
が優先的に成長し、そのためデンドライトの主軸は冷却
側から断熱側に向けて伸びていき、従って、板厚方向に
凝固するからである。According to the directional solidification method, the directional solidification in the plate thickness direction is possible. According to the directional solidification method, a mold having one side heat insulation and one side cooling structure with respect to the plate thickness direction is used. Because the heat flow from the adiabatic side to the cooling side is caused by the pouring of the molten metal into the mold, even if primary crystals with various orientations crystallize on the mold surface, crystals with the optimum growth direction for the heat flow Only the primary axis of the dendrite grows from the cooling side toward the adiabatic side, and thus solidifies in the plate thickness direction.
【００１８】又、指向性凝固法によれば、最終凝固部が
断熱側に存在するため、鋳造欠陥を断熱側に集中除去す
ることが可能になり、従って、実質的に鋳造欠陥を低減
させ得る。これが、指向性凝固法によれば、鋳造欠陥が
少ないTiAl系合金圧延用素材が得られる理由である。Further, according to the directional solidification method, since the final solidified portion exists on the adiabatic side, it becomes possible to remove the casting defects in a concentrated manner on the adiabatic side. Therefore, the casting defects can be substantially reduced. . This is the reason why the TiAl-based alloy rolling material having few casting defects can be obtained by the directional solidification method.
【００１９】以上の知見に基づき、本発明に係るTiAl系
合金圧延用素材の製造方法は、主要成分としてTi及びAl
を含有するTiAl系合金溶湯を、板状キャビティを有し、
板厚方向に対して片側断熱、片側冷却構造の鋳型に注湯
して指向性凝固をさせることにより板状に鋳造するよう
にしている。従って、鋳造欠陥が少なく、且つ、加工性
に優れて熱間圧延を容易にし得るTiAl系合金圧延用素材
を製造し、得ることができるようになる。Based on the above findings, the method for producing a material for rolling a TiAl alloy according to the present invention has Ti and Al as main components.
A TiAl-based alloy melt containing a plate-shaped cavity,
In the plate thickness direction, one side is heat-insulated and one side is cooled and poured into a mold for directional solidification to cast the plate. Therefore, it becomes possible to manufacture and obtain a TiAl alloy rolling material that has few casting defects, is excellent in workability, and can facilitate hot rolling.
【００２０】一方、本発明に係るTiAl系合金圧延用素材
は、板厚方向に指向性凝固された板状のTiAl系合金より
なり、該合金の層状組織の長手方向と板厚方向とのなす
角度が30〜60°であるものとしている。従って、鋳造欠
陥が少なく、且つ、加工性に優れて熱間圧延を容易にし
得る。ここで、層状組織の長手方向と板厚方向とのなす
角度を30〜60°としているのは、30°未満又は60°超で
は圧延加工の際に変形し難く、圧延加工性が不充分とな
るからである。On the other hand, the material for rolling a TiAl alloy according to the present invention is made of a plate-shaped TiAl alloy which is directionally solidified in the plate thickness direction, and is formed by the longitudinal direction of the layered structure of the alloy and the plate thickness direction. It is assumed that the angle is 30 to 60 °. Therefore, there are few casting defects and the workability is excellent, and hot rolling can be facilitated. Here, the angle between the longitudinal direction of the layered structure and the plate thickness direction is 30 to 60 °, which is less than 30 ° or more than 60 °, which is difficult to deform during rolling, and the rolling workability is insufficient. Because it will be.
【００２１】前記TiAl系合金溶湯は主要成分としてTi及
びAlを含有するものであり、鋳造後は金属間化合物TiAl
を主要構成相とするものとなる。このTiAl系合金溶湯中
のAl量は30〜50at％にすることが望ましい（請求項２記
載のTiAl系合金圧延用素材の製造方法）。30at％未満で
は、α2 単相であり、α2 ＋γの層状組織とはならず、
50at％超ではγ単相であり、デンドライトアーム内しか
α2 ＋γの層状組織にならない傾向にあるからである。
尚、前記Ti及びAlの他に、必要な合金元素を含むことも
でき、又、不可避的不純物を含む場合もある。The TiAl-based alloy melt contains Ti and Al as main components. After casting, the intermetallic compound TiAl
Will be the main constituent phase. It is desirable that the amount of Al in the molten TiAl-based alloy be 30 to 50 at% (the manufacturing method of the material for rolling TiAl-based alloy according to claim 2). If it is less than 30 at%, a alpha 2 single phase, not the lamellar structure of the alpha 2 + gamma,
This is because if it exceeds 50 at%, it is a γ single phase, and the α 2 + γ layered structure tends to form only in the dendrite arm.
In addition to Ti and Al, necessary alloy elements may be contained, and inevitable impurities may be contained.
【００２２】前記鋳造の際の雰囲気として真空又は不活
性雰囲気が適用されることが望ましい（請求項３記載の
TiAl系合金圧延用素材の製造方法）。加工性を阻害する
酸素等の有害ガス元素の混入を確実に防止できるからで
ある。A vacuum or an inert atmosphere is preferably applied as the atmosphere during the casting (claim 3).
Manufacturing method of TiAl alloy rolling material). This is because it is possible to reliably prevent mixing of a harmful gas element such as oxygen that hinders workability.
【００２３】本発明において、TiAl系合金は金属間化合
物TiAlを主要構成相とするものである。金属間化合物Ti
AlはTiとAlとよりなる金属間化合物であり、TiとAlとの
原子比は通常１：１よりややTi-rich である（Tiに富
む）ような比である（Al：30〜50at％である）。In the present invention, the TiAl-based alloy contains intermetallic compound TiAl as a main constituent phase. Intermetallic compound Ti
Al is an intermetallic compound composed of Ti and Al, and the atomic ratio of Ti and Al is usually slightly Ti-rich (rich in Ti) than 1: 1 (Al: 30 to 50 at%). Is).
【００２４】TiAl系合金溶湯を得るための溶解法として
は、例えばコールドクルーシブル誘導溶解炉による溶解
法、真空アーク溶解、耐火物ルツボによる真空誘導溶解
法等を適用できるが、溶解の際の不純物汚染を極力抑制
すると共に成分偏析のない均質なものとするためにはコ
ールドクルーシブル誘導溶解炉による溶解法を採用する
ことが望ましい。溶解の主原料としてはTiAl系合金や、
Ti材とAl材とを配合したものを使用でき、溶解温度は約
1700〜1500℃にすればよい。As a melting method for obtaining a TiAl alloy molten metal, for example, a melting method using a cold crucible induction melting furnace, a vacuum arc melting method, a vacuum induction melting method using a refractory crucible, etc. can be applied, but impurity contamination during melting can be applied. It is desirable to adopt a melting method using a cold crucible induction melting furnace in order to suppress the temperature as much as possible and to make the material homogeneous without segregation of components. As the main raw material for melting TiAl alloy,
A mixture of Ti material and Al material can be used, and the melting temperature is about
The temperature may be 1700 to 1500 ° C.
【００２５】鋳型としては、板状キャビティを有し、板
厚方向に対して片側断熱、片側冷却構造のものとする必
要があるが、そのためには例えば片側をアルミナ系耐火
ボード、Y2O3系耐火物の如く熱伝導率の低い材質で構成
し、片側（対向面側）を黒鉛、水冷された銅の如く熱伝
導率の高い材質で構成すればよい。上記板状キャビティ
は、板状であればよく、キャビティ面が平行である必要
はない。板状キャビティ寸法としては、例えば、厚み１
〜10×深さ100 〜500 ×幅50〜500 mmであればよい。鋳
型に注湯する溶湯の温度は、約1500〜1700℃にすればよ
い。It is necessary that the mold has a plate-shaped cavity and has one-sided heat insulation and one-sided cooling structure in the plate thickness direction. For that purpose, for example, one side is an alumina-based refractory board, Y 2 O 3 It may be made of a material having a low thermal conductivity such as a system refractory and one having a high thermal conductivity such as graphite or water-cooled copper on one side (opposing surface side). The plate-shaped cavity may be plate-shaped, and the cavity surfaces do not need to be parallel. The plate-shaped cavity has a thickness of, for example, 1
-10 x depth 100-500 x width 50-500 mm. The temperature of the molten metal poured into the mold may be about 1500 to 1700 ° C.
【００２６】注湯後の凝固速度即ち鋳造速度は、早すぎ
ると完全充填せず（充填不完全となり）、遅すぎると層
状組織が粗くなる傾向にあり、かかる点から10〜100 ℃
／秒とすればよく、望ましくは30〜100 ℃／秒とするの
がよく、特には50〜100 ℃／秒とすることが好ましい。The solidification rate after pouring, that is, the casting rate, is such that if it is too fast, it will not be completely filled (incomplete filling), and if it is too slow, the layered structure will tend to become rough.
/ Sec, preferably 30 to 100 ° C / sec, and particularly preferably 50 to 100 ° C / sec.
【００２７】[0027]
【実施例】本発明の実施例を以下説明するが、これによ
って本発明は何ら限定されるものではない。Ti-46 at%
(原子%)Al合金をコールドクルーシブル誘導溶解炉によ
り溶製した。このとき、溶解原料としては JIS１種の純
Ti原料、99.99%の純Al原料を用いた。溶解の雰囲気とし
ては、Al蒸発防止のため、Ar 2.666×104Pa 雰囲気とし
た。EXAMPLES Examples of the present invention will be described below, but the present invention is not limited thereto. Ti-46 at%
(Atomic%) Al alloy was melted in a cold crucible induction melting furnace. At this time, as the melting raw material, JIS Class 1 pure
A Ti raw material and a 99.99% pure Al raw material were used. The melting atmosphere was an Ar 2.666 × 10 4 Pa atmosphere to prevent evaporation of Al.
【００２８】このようにして得られたTiAl系合金溶湯
を、幅 160×深さ300 ×厚み６mmの板状キャビティを有
し、板厚方向に対して片側断熱、片側冷却構造の鋳型に
注湯して指向性凝固をさせることにより薄板状に鋳造
し、薄板状鋳片即ちTiAl系合金圧延用薄板状素材（以
下、指向性凝固素材という）を得た。このとき、鋳型を
板厚方向に対して片側断熱、片側冷却構造とするため、
片側を熱伝導率の低い材質、片側（対向面側）を熱伝導
率の高い材質で構成した。具体的には冷却側を黒鉛、断
熱側をアルミナ系耐火ボードで構成した鋳型を使用し
た。板状キャビティ厚さは、凝固収縮分と欠陥除去部分
を考慮して６mmとした。また、低温での冷却中凝固収縮
による反り、割れの発生を防止するため、抵抗加熱式ヒ
ータを断熱側に設置し、鋳型の断熱側の温度を500 ℃に
した。鋳型に注湯する溶湯の温度は1500〜1700℃であ
る。鋳造の際、ガス欠陥低減のため、チャンバーからAr
を排気し、Ar2.666 ×103Pa 雰囲気にして鋳造した。The TiAl alloy melt thus obtained is poured into a mold having a plate-shaped cavity having a width of 160 × a depth of 300 × a thickness of 6 mm and having one-side heat insulation and one-side cooling structure in the plate thickness direction. Then, it was cast into a thin plate by directional solidification to obtain a thin slab, that is, a thin plate material for rolling TiAl alloy (hereinafter referred to as directional solidification material). At this time, since the mold has a one-side heat insulation and one-side cooling structure in the plate thickness direction,
One side was made of a material having low thermal conductivity and one side (opposing side) was made of a material having high thermal conductivity. Specifically, a mold having graphite on the cooling side and alumina refractory board on the heat insulating side was used. The thickness of the plate-like cavity was set to 6 mm in consideration of the solidification shrinkage and the defect removed portion. In order to prevent warpage and cracking due to solidification shrinkage during cooling at low temperature, a resistance heating heater was installed on the heat insulating side, and the temperature on the heat insulating side of the mold was set to 500 ° C. The temperature of the molten metal poured into the mold is 1500 to 1700 ° C. During casting, Ar is removed from the chamber to reduce gas defects.
Was evacuated and cast in an atmosphere of Ar 2.666 × 10 3 Pa.
【００２９】一方、比較のため、上記実施例１と同様の
溶湯を幅 160×深さ210 ×厚み80mmのブック状キャビテ
ィーを有する黒鉛鋳型に注湯して鋳造し、板状鋳片（以
下、通常凝固鋳片）を得た後、該鋳片から板厚４mmの圧
延用素材（以下、通常素材）を機械加工により切り出し
た。尚、この場合、鋳造の際の凝固は指向性凝固ではな
く、所謂通常凝固であり、層状組織が30〜60°となると
は限らない。On the other hand, for comparison, the same molten metal as in Example 1 was poured into a graphite mold having a book-shaped cavity having a width of 160 × a depth of 210 × a thickness of 80 mm and cast to obtain a plate-shaped slab (hereinafter referred to as a slab). After obtaining a normally solidified slab, a material for rolling having a plate thickness of 4 mm (hereinafter, ordinary material) was cut out from the slab by machining. In this case, solidification at the time of casting is not directional solidification but so-called normal solidification, and the layered structure does not always become 30 to 60 °.
【００３０】上記指向性凝固素材の外観を観察したとこ
ろ、溶湯は充分に充填されており、板表面は冷却側につ
いては金属光沢を有していて非常に美麗であり、断熱側
もアルミナ系耐火ボードとの反応は起こっておらず、該
ボードの凹凸模様が転写されている状態であった。断熱
側表面に引け巣欠陥が認められた。The appearance of the above directional solidified material was observed, and it was found that the molten metal was sufficiently filled, the plate surface had a metallic luster on the cooling side and was very beautiful, and the heat insulating side was also alumina fire resistant. No reaction with the board had occurred and the uneven pattern of the board had been transferred. A shrinkage cavity defect was recognized on the heat insulating side surface.
【００３１】上記指向性凝固素材のマクロ組織を調べた
ところ、引け巣等の鋳造欠陥は最終凝固部の断熱側（ア
ルミナ系耐火ボード側）に集中除去されていることが確
認された。その結果の一例をマクロ組織の模式図で図１
に示す。又、上記指向性凝固素材のＸ線透過試験をした
ところ、引け巣欠陥は認められず、更に、ガス欠陥も低
減されていることが確認された。従って、指向性凝固に
より、最終凝固部が断熱側近傍に位置し、実質的に鋳造
欠陥が著しく低減することがわかる。When the macrostructure of the directional solidified material was examined, it was confirmed that casting defects such as shrinkage cavities were concentratedly removed on the heat insulating side (alumina-based refractory board side) of the final solidified portion. An example of the result is shown in the schematic diagram of macro organization in FIG.
Shown in. In addition, when an X-ray transmission test was conducted on the above directional solidification material, shrinkage cavity defects were not recognized, and it was further confirmed that gas defects were also reduced. Therefore, it can be seen that the directional solidification causes the final solidified portion to be located in the vicinity of the heat insulating side, so that casting defects are substantially reduced.
【００３２】上記指向性凝固素材のミクロ組織模式図を
図２に示す。両鋳型面近傍にチル晶が形成された後、熱
流の方向（凝固進行方向）に平行な結晶が優先生長した
と考えられる柱状晶帯が鋳型冷却側（黒鉛側）から断熱
側（アルミナ系耐火ボード側）に伸びて形成されてお
り、層状のラメラー組織は凝固進行方向に対して45°程
度の角度を有していることがわかる。尚、通常凝固鋳片
の場合には、層状のラメラー組織がランダムな方向を向
いた等軸粒組織となっており、層状組織の方向性は認め
られない。従って、指向性凝固によって圧延加工に有利
な方向に層状組織を制御できることがわかる。FIG. 2 shows a schematic diagram of the microstructure of the directional solidification material. After the formation of chill crystals near both mold surfaces, the columnar crystal bands, which are considered to have preferentially grown crystals parallel to the direction of heat flow (solidification progress direction), are from the mold cooling side (graphite side) to the heat insulation side (alumina-based refractory). It can be seen that the layered lamellar structure is formed to extend to the board side) and has an angle of about 45 ° with respect to the solidification progress direction. In the case of a normally solidified cast slab, the lamellar lamellar structure is an equiaxed grain structure oriented in random directions, and the orientation of the lamellar structure is not recognized. Therefore, it is understood that the directional solidification can control the layered structure in a direction advantageous for rolling.
【００３３】上記指向性凝固素材及び通常素材につい
て、圧延温度1100℃（一定）、ひずみ速度10-3／秒で恒
温圧延を行い、圧下率と平均変形圧力（変形抵抗）との
関係を調べた。その結果を図３に示す。指向性凝固素材
の方が変形抵抗が小さく、指向性凝固によって圧延加工
性が著しく向上することがわかる。The above directional solidified material and ordinary material were subjected to isothermal rolling at a rolling temperature of 1100 ° C. (constant) and a strain rate of 10 −3 / sec, and the relationship between the rolling reduction and the average deformation pressure (deformation resistance) was investigated. . The result is shown in FIG. It can be seen that the directional solidification material has a smaller deformation resistance, and the rolling workability is significantly improved by the directional solidification.
【００３４】[0034]
【発明の効果】本発明によれば、鋳造欠陥が少なく、且
つ、加工性に優れて熱間圧延を容易にし得るTiAl系合金
圧延用素材が得られるようになり、引いては、欠陥がな
くて良好なTiAl系合金板を容易に圧延して得られるよう
になる。EFFECTS OF THE INVENTION According to the present invention, it is possible to obtain a material for rolling a TiAl-based alloy which has few casting defects and is excellent in workability and can facilitate hot rolling. And good TiAl alloy plate can be easily rolled.
【図１】 本発明の実施例に係る指向性凝固素材のマク
ロ組織を示す模式図である。FIG. 1 is a schematic diagram showing a macrostructure of a directional solidification material according to an example of the present invention.
【図２】 本発明の実施例に係る指向性凝固素材のミク
ロ組織を示す模式図である。FIG. 2 is a schematic diagram showing a microstructure of a directional solidification material according to an example of the present invention.
【図３】 本発明の実施例に係る指向性凝固素材及び比
較例に係る通常素材についての恒温圧延の際の圧下率と
変形抵抗との関係を示す図である。FIG. 3 is a diagram showing the relationship between the rolling reduction and the deformation resistance during isothermal rolling of the directional solidified material according to the example of the present invention and the normal material according to the comparative example.
Claims (4)
系合金溶湯を、板状キャビティを有し、板厚方向に対し
て片側断熱、片側冷却構造の鋳型に注湯して指向性凝固
をさせることにより板状に鋳造することを特徴とするTi
Al系合金圧延用素材の製造方法。1. A TiAl containing Ti and Al as main components.
Ti-based molten alloy having a plate-shaped cavity, which is cast in a plate shape by pouring into a mold having one-sided heat insulation and one-sided cooling structure in the plate thickness direction and directional solidification
A method for producing a material for rolling an Al-based alloy.
％である請求項１記載のTiAl系合金圧延用素材の製造方
法。2. The amount of Al in the molten TiAl-based alloy is 30 to 50 at
%, The method for producing a material for rolling a TiAl-based alloy according to claim 1.
活性雰囲気が適用される請求項１又は２記載のTiAl系合
金圧延用素材の製造方法。3. The method for manufacturing a TiAl alloy rolling material according to claim 1, wherein a vacuum or an inert atmosphere is applied as the atmosphere during the casting.
系合金よりなり、該合金の層状組織の長手方向と板厚方
向とのなす角度が30〜60°であることを特徴とするTiAl
系合金圧延用素材。4. A plate-shaped TiAl directionally solidified in the plate thickness direction.
TiAl, which is made of a system alloy and has an angle between the longitudinal direction of the layered structure of the alloy and the plate thickness direction of 30 to 60 °.
Material for rolling alloys.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP11118294A JPH07316683A (en) | 1994-05-25 | 1994-05-25 | Blank for rolling titanium-aluminum alloy and its production |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP11118294A JPH07316683A (en) | 1994-05-25 | 1994-05-25 | Blank for rolling titanium-aluminum alloy and its production |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH07316683A true JPH07316683A (en) | 1995-12-05 |
Family
ID=14554579
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP11118294A Pending JPH07316683A (en) | 1994-05-25 | 1994-05-25 | Blank for rolling titanium-aluminum alloy and its production |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH07316683A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2002317234A (en) * | 2001-02-16 | 2002-10-31 | Kobe Steel Ltd | Titanium sheet having excellent ductility and production method therefor |
| US20110311835A1 (en) * | 2009-02-09 | 2011-12-22 | Kazuhiro Takahashi | Titanium slab for hot rolling, and method of producing and method of rolling the same |
-
1994
- 1994-05-25 JP JP11118294A patent/JPH07316683A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2002317234A (en) * | 2001-02-16 | 2002-10-31 | Kobe Steel Ltd | Titanium sheet having excellent ductility and production method therefor |
| US20110311835A1 (en) * | 2009-02-09 | 2011-12-22 | Kazuhiro Takahashi | Titanium slab for hot rolling, and method of producing and method of rolling the same |
| US9719154B2 (en) * | 2009-02-09 | 2017-08-01 | Nippon Steel & Sumitomo Metal Corporation | Titanium slab for hot rolling, and method of producing and method of rolling the same |
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