JP2012214860A - Titanium sheet having high strength and excellent press formability - Google Patents
Titanium sheet having high strength and excellent press formability Download PDFInfo
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本発明は、高耐力で且つプレス加工等の成形性に優れたチタン板に関するものである。 The present invention relates to a titanium plate having high yield strength and excellent formability such as press working.
チタンは優れた耐食性並びに比強度を有することから、熱交換器、化学プラント部材、或いは海岸部の構造材等に広く採用されており、特に海水に対しては全く腐食しないことから海水熱交換器に採用されることが多い。中でも、プレート式熱交換器には板状に加工したチタン板が採用されており、伝熱効率向上のために表面を凹凸形状にプレス成形したチタン板が用いられている。また、近年は伝熱効率を更に向上させるため、チタン板を薄肉化させる、凹凸形状を複雑化させるといったニーズがあり、高耐力で且つプレス成形等の成形性が更に優れたチタン板が開発されることが待望されているという背景もあり、高耐力でプレス成形性に優れたチタン板に関しては、そのチタン板の材質等の構成並びにその成形加工技術に関する様々な提案がある。 Titanium has excellent corrosion resistance and specific strength, so it is widely used in heat exchangers, chemical plant members, coastal structural materials, etc., especially seawater, so it does not corrode at all. It is often adopted for. In particular, a plate-type heat exchanger employs a titanium plate processed into a plate shape, and a titanium plate whose surface is press-formed into an uneven shape is used to improve heat transfer efficiency. In recent years, in order to further improve the heat transfer efficiency, there is a need for thinning the titanium plate and complicating the concavo-convex shape, and a titanium plate having high yield strength and further excellent formability such as press molding is developed. With regard to the titanium plate having high yield strength and excellent press formability, there are various proposals regarding the structure of the material of the titanium plate and the forming technique thereof.
チタンの材質面では、チタンの結晶構造が六方晶であるために異方性があることから、特許文献１として、通常の圧延方向と直角に圧延して、異方性を低減する方法が提案されている。しかしながら、この方法では、製造工程の途中で圧延方向を変更しなければならないため、生産性を落とさざるを得ないという実情があった。 Since the titanium crystal structure is hexagonal in terms of the material of titanium, there is anisotropy. Therefore, Patent Document 1 proposes a method of reducing anisotropy by rolling at a right angle to the normal rolling direction. Has been. However, in this method, since the rolling direction has to be changed in the middle of the manufacturing process, there is a fact that productivity has to be reduced.
成形加工技術の観点からは、表面潤滑の適正化等が検討されており、例えば、特許文献２として、板材の表面に潤滑剤キャリアの鉄、亜鉛合金層を形成させ、その後、リン酸亜鉛処理を行い、潤滑剤を塗布するという方法が提案されている。しかしながら、この方法では、潤滑剤処理に多数の工程が必要となり、その面で不効率な方法であった。 From the viewpoint of forming technology, optimization of surface lubrication has been studied. For example, as Patent Document 2, an iron or zinc alloy layer of a lubricant carrier is formed on the surface of a plate material, and then zinc phosphate treatment is performed. And a method of applying a lubricant has been proposed. However, this method requires many steps for the lubricant treatment, and is inefficient in that respect.
また、板材の表面潤滑性に着目した提案も多くあり、特許文献３および特許文献４として、板材の表面に酸化被膜を形成させたチタン板とその製造方法が、特許文献５として、板材の表面に窒素富化層を形成させたチタン板とその製造方法が、特許文献６として、板材の表面にＴｉＣ含有層を形成させたチタン板が、夫々提案されている。しかしながら、これらのチタン板やその製造方法では、板材の表面に被覆層を形成する必要があり、その製造工程が複雑であるという実情があった。 In addition, there are many proposals focusing on the surface lubricity of the plate material. Patent Documents 3 and 4 disclose a titanium plate having an oxide film formed on the surface of the plate material and a manufacturing method thereof as Patent Document 5 and the surface of the plate material. A titanium plate having a nitrogen-enriched layer formed thereon and a method for producing the same have been proposed as Patent Document 6, and a titanium plate having a TiC-containing layer formed on the surface of a plate material has been proposed. However, in these titanium plates and their manufacturing methods, it is necessary to form a coating layer on the surface of the plate material, and the manufacturing process is complicated.
本発明は、上記従来の問題を解決せんとしてなされたもので、高耐力であると共にプレス成形性に優れたチタン板を提供することを課題とするものである。 The present invention has been made as a solution to the above-described conventional problems, and an object of the present invention is to provide a titanium plate having high yield strength and excellent press formability.
請求項１記載の発明は、質量％で、Ｆｅを０．０４〜０．０６％、Ｏを０．０７〜０．１１％含有し、残部がＴｉおよび不可避的不純物であって、１／４ｔ（ｔは板厚）部の圧延面における、圧延方向引張時の｛１１−２２｝＜１１−２３＞双晶変形のシュミット因子の平均値が０．４０以上であることを特徴とする高耐力でプレス成形性に優れたチタン板である。 The invention according to claim 1 is mass%, containing 0.04 to 0.06% Fe, 0.07 to 0.11% O, the balance being Ti and inevitable impurities, and 1/4 t The high yield strength, wherein the average value of the Schmid factor of {11-22} <11-23> twin deformation at the time of rolling in the rolling direction on the rolled surface of the portion (t is the plate thickness) is 0.40 or more. It is a titanium plate with excellent press formability.
請求項２記載の発明は、１／４ｔ（ｔは板厚）部の１ｍｍ×１ｍｍの平面内に存在する結晶粒（α相）の平均結晶粒径が、７５〜２００μｍである請求項１記載の高耐力でプレス成形性に優れたチタン板である。 According to a second aspect of the present invention, the average crystal grain size of crystal grains (α phase) existing in a 1 mm × 1 mm plane of a 1/4 t (t is a plate thickness) portion is 75 to 200 μm. It is a titanium plate with high yield strength and excellent press formability.
本発明によると、高耐力でプレス成形性に優れたチタン板を得ることができる。また、チタン本来の優れた耐久性はもとより、高い機械的強度に加えて、優れたプレス成形性を有しているので、プレート式熱交換器の構成材のほか、燃料電池のセパレーター、携帯電話機、モバイルパソコン、カメラのボディ、眼鏡フレーム等、高耐力で高度な成形性が要求される用途に広く適用することができる。 According to the present invention, a titanium plate having high yield strength and excellent press formability can be obtained. In addition to the excellent durability inherent in titanium, in addition to high mechanical strength, it also has excellent press formability, so in addition to plate heat exchanger components, fuel cell separators, mobile phones It can be widely applied to applications requiring high strength and high formability, such as mobile personal computers, camera bodies, and eyeglass frames.
また、結晶粒（α相）の平均結晶粒径を、請求項２に記載のように適切に制御することで、高耐力で、更に優れたプレス成形性を得ることができる。 Further, by appropriately controlling the average crystal grain size of the crystal grains (α phase) as described in claim 2, it is possible to obtain a further excellent press formability with high yield strength.
本発明者らは、高耐力でプレス成形性に優れたチタン板を得るために、鋭意、実験、研究を進めた。その結果、Ｆｅの含有量とＯの含有量を規定すると共に、そのチタン板の１／４ｔ（ｔは板厚）部の圧延面における圧延方向引張時の｛１１−２２｝＜１１−２３＞双晶変形のシュミット因子の平均値を、適切に制御することで、高耐力で、優れたプレス成形性を確保することが可能になることを見出し、本発明の完成に至った。 In order to obtain a titanium plate having high yield strength and excellent press formability, the present inventors have advanced earnestly, experiment and research. As a result, the content of Fe and the content of O are defined, and {11-22} <11-23> at the time of rolling in the rolling surface of the 1/4 t (t is the plate thickness) portion of the titanium plate. It has been found that by appropriately controlling the average value of the Schmid factor of twin deformation, it is possible to ensure excellent press formability with high yield strength, and the present invention has been completed.
また、それに加えて、チタン板の１／４ｔ（ｔは板厚）部の平面の１ｍｍ×１ｍｍ内に存在する結晶粒（α相）の平均結晶粒径を、適切に制御することで、高耐力で、更に優れたプレス成形性を確保したチタン板とすることができることも確認した。 In addition to that, by appropriately controlling the average crystal grain size of the crystal grains (α phase) existing within 1 mm × 1 mm of the plane of the 1/4 t (t is the plate thickness) portion of the titanium plate, It was also confirmed that the titanium plate can secure a further excellent press formability in terms of yield strength.
以下、本発明を実施形態に基づき詳細に説明する。 Hereinafter, the present invention will be described in detail based on embodiments.
本発明では、チタン板の成分組成と、そのチタン板の１／４ｔ（ｔは板厚）部の圧延面における圧延方向引張時の｛１１−２２｝＜１１−２３＞双晶変形のシュミット因子の平均値を規定するが、まず、成分組成について説明する。 In the present invention, the component composition of the titanium plate and the Schmid factor of {11-22} <11-23> twin deformation at the time of rolling in the rolling surface of the 1/4 t (t is the plate thickness) portion of the titanium plate. First, the component composition will be described.
（成分組成）
純チタンは、不可避的不純物としてＣ、Ｈ、Ｏ、Ｎ、Ｆｅ等を微量に含有するが、本発明では、その中でも含有量が比較的多く、機械的性質に影響を及ぼすＦｅとＯの含有量を規定した。
(Component composition)
Pure titanium contains a small amount of C, H, O, N, Fe, etc. as unavoidable impurities, but in the present invention, the content is relatively large, and the inclusion of Fe and O that affects mechanical properties. The amount was specified.
Ｆｅの含有量が０．０６質量％を超えて多くなりすぎると、耐力が大きくなりすぎてプレス成形性が低下する傾向がある。従って、Ｆｅの含有量の上限は０．０６質量％とする。一方、Ｆｅの含有量が０．０４質量％より少なくなると耐力が小さくなりすぎるので、Ｆｅの含有量の下限は０．０４質量％とする。 If the Fe content exceeds 0.06% by mass, the proof stress tends to be too high and the press formability tends to decrease. Therefore, the upper limit of the Fe content is 0.06% by mass. On the other hand, if the Fe content is less than 0.04% by mass, the yield strength becomes too small, so the lower limit of the Fe content is 0.04% by mass.
Ｏの含有量が０．１１質量％を超えて多くなりすぎると、耐力が大きくなりすぎてプレス成形性が低下する傾向がある。従って、Ｏの含有量の上限は０．１１質量％とする。一方、Ｏの含有量が０．０７質量％より少なくなると耐力が小さくなりすぎるので、Ｏの含有量の下限は０．０７質量％とする。 If the O content exceeds 0.11% by mass, the proof stress tends to be too high, and the press formability tends to decrease. Therefore, the upper limit of the O content is 0.11% by mass. On the other hand, if the O content is less than 0.07% by mass, the yield strength becomes too small, so the lower limit of the O content is 0.07% by mass.
（圧延方向引張時の｛１１−２２｝＜１１−２３＞双晶変形のシュミット因子の平均値）
チタン板の１／４ｔ（ｔは板厚）部の圧延面における圧延方向引張時の｛１１−２２｝＜１１−２３＞双晶変形のシュミット因子（Ｓｃｈｍｉｄ ｆａｃｔｏｒ）の平均値が小さすぎると、チタン板の成形時に発生する変形双晶の頻度が少なくなりすぎて、本発明で意図する優れたプレス成形性を得られなくなってしまう。本発明で意図する優れたプレス成形性を確保するためには、前記した圧延方向引張時の｛１１−２２｝＜１１−２３＞双晶変形のシュミット因子の平均値が０．４以上でなければならない。好ましくはシュミット因子の平均値を０．４２以上、より好ましくはシュミット因子の平均値を０．４４以上とする必要がある。尚、このシュミット因子の平均値は理論上０．５を超えることはない。
(Average value of Schmid factor of {11-22} <11-23> twin deformation during rolling direction tension)
When the average value of the Schmid factor of {11-22} <11-23> twin deformation at the time of rolling in the rolling direction of the 1/4 t (t is the plate thickness) portion of the titanium plate is too small, The frequency of deformation twins generated at the time of forming the titanium plate is too low, and the excellent press formability intended in the present invention cannot be obtained. In order to ensure the excellent press formability intended in the present invention, the average value of the Schmid factor of {11-22} <11-23> twin deformation at the time of rolling in the rolling direction described above must be 0.4 or more. I must. The average value of the Schmitt factor is preferably 0.42 or more, and more preferably the average value of the Schmitt factor is 0.44 or more. Note that the average value of the Schmitt factor does not theoretically exceed 0.5.
また、以上説明したチタン板の成分組成と圧延方向引張時の｛１１−２２｝＜１１−２３＞双晶変形のシュミット因子の平均値を規定することに加えて、１／４ｔ（ｔは板厚）部の１ｍｍ×１ｍｍの平面内に存在する結晶粒（α相）の平均結晶粒径を規定することで、高耐力で、十分なプレス成形性を確保することができるが、その理由を以下に説明する。 In addition to defining the component composition of the titanium plate described above and the average value of the Schmid factor of {11-22} <11-23> twinning deformation in the rolling direction, 1/4 t (t is the plate By defining the average crystal grain size of the crystal grains (α phase) existing in the 1 mm x 1 mm plane of the (thickness) part, it is possible to ensure sufficient press formability with high yield strength. This will be described below.
（結晶粒の平均結晶粒径）
結晶粒（α相）の平均結晶粒径が大きくなりすぎると、プレス成形時のチタン板の肌荒れが顕著になり、より厳しい条件での成形では割れが生じやすくなる。従って、結晶粒（α相）の平均結晶粒径は、２００μｍ以下であることが好ましい。より好ましい上限は１７５μｍ、更に好ましい上限は１５０μｍである。一方、平均結晶粒径が小さすぎると変形時の変形双晶頻度が少なくなり、プレス成形性が低下する。従って、結晶粒（α相）の平均結晶粒径は、７５μｍ以上であることが好ましい。より好ましい下限は１００μｍである。
(Average crystal grain size of crystal grains)
If the average crystal grain size of the crystal grains (α phase) becomes too large, the rough surface of the titanium plate during press molding becomes prominent, and cracking is likely to occur in molding under more severe conditions. Accordingly, the average crystal grain size of the crystal grains (α phase) is preferably 200 μm or less. A more preferred upper limit is 175 μm, and a still more preferred upper limit is 150 μm. On the other hand, if the average crystal grain size is too small, the deformation twinning frequency at the time of deformation decreases, and the press formability decreases. Accordingly, the average crystal grain size of the crystal grains (α phase) is preferably 75 μm or more. A more preferred lower limit is 100 μm.
（製造条件）
次に、本発明のチタン板の製造方法について説明する。通常のチタン板は、分塊圧延→熱間圧延→中間焼鈍→冷間圧延→最終焼鈍といった各工程間に、随時ブラスト、酸洗処理を入れて製造されるが、製造するチタン板の成分組成や各工程の設定条件によって、得られる物性や組織状態は変わるので、一連の製造工程として総合的に条件を選択して決定すべきであって、個々の工程毎に条件を厳密に設定することは必ずしも適切でない。
(Production conditions)
Next, the manufacturing method of the titanium plate of this invention is demonstrated. Ordinary titanium plates are manufactured by adding blasting and pickling treatment at any time between each process of lump rolling → hot rolling → intermediate annealing → cold rolling → final annealing, but the component composition of the titanium plate to be manufactured Since the physical properties and structure of the product to be obtained vary depending on the setting conditions of each process, the conditions should be selected and determined comprehensively as a series of manufacturing processes, and the conditions must be set strictly for each process. Is not necessarily appropriate.
しかしながら、本発明のチタン板を製造するための製造条件を、本発明者らが鋭意検討したところ、以下に示す製造条件を採用することで、本発明で意図する高耐力でプレス成形性に優れたチタン板を確実に製造することができることを確認した。 However, when the present inventors diligently studied the production conditions for producing the titanium plate of the present invention, by adopting the production conditions shown below, the high yield strength and excellent press formability intended by the present invention are achieved. It was confirmed that the titanium plate can be manufactured reliably.
その製造条件は、分塊圧延、熱間圧延、冷間圧延を全て同一方向で行うと共に、最終焼鈍の焼鈍温度を８３０℃〜Ｔβ、その焼鈍時間を５分以上とすることである。これらの条件を適切に組み合わせてチタン板を製造することで、本発明で意図する高耐力でプレス成形性に優れたチタン板を製造することができる。 The manufacturing conditions are to perform all the partial rolling, hot rolling, and cold rolling in the same direction, the annealing temperature of the final annealing is 830 ° C. to Tβ, and the annealing time is 5 minutes or more. By appropriately combining these conditions to produce a titanium plate, it is possible to produce a titanium plate having high yield strength and excellent press formability intended in the present invention.
尚、一般にチタン板を製造するときの条件は、最終焼鈍の焼鈍温度を８００℃前後、焼鈍時間を１分以上５分未満とするか、或いは、最終焼鈍の焼鈍温度をそれより低温とし、焼鈍時間をそれより長時間とする。また、本発明では、最終焼鈍前の冷延率については特に規定しないが、通常は５０〜６０％の範囲の冷延率で最終焼鈍前の冷間圧延は行われる。 In general, the conditions for producing a titanium plate are as follows: the annealing temperature for final annealing is around 800 ° C., the annealing time is 1 minute or more and less than 5 minutes, or the annealing temperature for final annealing is lower than that, and annealing is performed. Make the time longer. Moreover, in this invention, although it does not prescribe | regulate especially about the cold rolling rate before the last annealing, Usually, the cold rolling before the last annealing is performed by the cold rolling rate of the range of 50 to 60%.
以下、実施例を挙げて本発明をより具体的に説明するが、本発明はもとより下記実施例によって制限を受けるものではなく、本発明の趣旨に適合し得る範囲で適宜変更を加えて実施することも可能であり、それらは何れも本発明の技術的範囲に含まれる。 EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited by the following examples, and the present invention is implemented with appropriate modifications within a range that can meet the gist of the present invention. These are all included in the technical scope of the present invention.
本実施例では、まず、ＣＣＩＭ（コールドクルーシブル誘導溶解法）により表１に示す含有量でＦｅ並びにＯを含有するチタン鋳塊を鋳造した。残部はＴｉおよびＣ、Ｈ、Ｎ、等の不可避的不純物である。鋳塊の大きさはφ１００ｍｍの円柱形で、１０ｋｇである。この鋳塊を用いて分塊圧延を行い、その後は放冷して厚み４５ｍｍの板形状の分塊圧延材を得た。更に、熱間圧延を実施し、スケール除去を行い厚み約４ｍｍの熱延板を得た。 In this example, first, a titanium ingot containing Fe and O at the contents shown in Table 1 was cast by CCIM (cold crucible induction melting method). The balance is Ti and unavoidable impurities such as C, H, N, and the like. The size of the ingot is 10 kg in a cylindrical shape of φ100 mm. Using this ingot, the ingot rolling was performed, and then cooled to obtain a plate-like ingot rolled material having a thickness of 45 mm. Furthermore, hot rolling was performed, scale removal was performed, and a hot rolled sheet having a thickness of about 4 mm was obtained.
次いで、大気炉にて、７００℃で５分間加熱してから空冷する焼鈍処理（中間焼鈍）を行った後、スケール除去を行い、冷間圧延を実施した。この作業を２回繰り返した後に、大気炉にて、表１に示す条件で加熱してから空冷する焼鈍処理（最終焼鈍）を行い、スキンパスを実施し、スケール除去を行って厚み０．５ｍｍのチタン板を製造した。 Subsequently, after performing an annealing process (intermediate annealing) in which air cooling was performed at 700 ° C. for 5 minutes in an atmospheric furnace, scale removal was performed and cold rolling was performed. After repeating this operation twice, an annealing process (final annealing) is performed by heating in an atmospheric furnace under the conditions shown in Table 1, followed by air cooling, skin pass is performed, scale removal is performed, and the thickness is 0.5 mm. A titanium plate was produced.
本実施例では、製造した各チタン板の金属組織等の観察・測定と、耐力およびプレス成形性の評価を夫々下記の要領で行った。 In this example, observation and measurement of the metal structure and the like of each manufactured titanium plate and evaluation of proof stress and press formability were performed in the following manner.
本実施例では、電界放出型走査顕微鏡（Ｆｉｅｌｄ Ｅｍｉｓｓｉｏｎ Ｓｃａｎｎｉｎｇ Ｅｌｅｃｔｒｏｎ Ｍｉｃｒｏｓｃｏｐｅ：ＦＥＳＥＭ）（日本電子社製、ＪＳＭ５４１０）に、後方錯乱電子回析像（Ｅｌｅｃｔｒｏｎ Ｂａｃｋ Ｓｃａｔｔｅｒｉｎｇ（Ｓｃａｔｔｅｒｅｄ） Ｐａｔｔｅｒｎ：ＥＢＳＰ）システムを搭載した結晶方位解析法によって金属組織の観察・測定を実施した。この測定方法を用いたのは、ＥＢＳＰ法は他の測定方法と比較して高分解能であり、高精度な測定ができるためである。まず、測定原理について説明する。 In this example, a field emission scanning electron microscope (FESEM) (manufactured by JEOL Ltd., JSM5410) is equipped with a back-scattered electron diffraction image (Electron Back Scattering (Scattered) Pattern system). The metal structure was observed and measured by the crystal orientation analysis method. This measurement method was used because the EBSP method has higher resolution than other measurement methods and can perform measurement with high accuracy. First, the measurement principle will be described.
ＥＢＳＰ法は、ＦＥＳＥＭの鏡筒内にセットした試料に電子線を照射してスクリーン上にＥＢＳＰを投影する。これを高感度カメラで撮影して、コンピュータに画像として取り込む。この画像を解析して、既知の結晶系を用いたシミュレーションによるパターンとの比較によって、結晶の方位が決定される。算出された結晶の方位は３次元オイラー角として、位置座標（ｘ、ｙ）などと共に記録される。このプロセスが全測定点に対して自動的に行われるので、測定終了時には数万〜数十万点のデータを得ることができる。 In the EBSP method, an electron beam is irradiated onto a sample set in a lens barrel of FESEM to project EBSP on a screen. This is taken with a high-sensitivity camera and captured as an image on a computer. The orientation of the crystal is determined by analyzing this image and comparing it with a pattern obtained by simulation using a known crystal system. The calculated crystal orientation is recorded as a three-dimensional Euler angle together with position coordinates (x, y) and the like. Since this process is automatically performed for all measurement points, data of tens of thousands to hundreds of thousands of points can be obtained at the end of measurement.
このように、ＥＢＳＰ法には、Ｘ線回析法や透過電子顕微鏡を用いた電子線回析法よりも、観察視野が広く、数百個以上の多数の結晶粒に対する各種情報を、数時間以内で得ることができる利点がある。また、結晶粒毎の測定ではなく、指定した領域を一定間隔で走査して測定するために、測定領域全体を網羅した上記多数の測定ポイントに関する、上記各情報を得ることができる利点もある。尚、これらＦＥＳＥＭにＥＢＳＰシステムを搭載した結晶方位解析法の詳細は、神戸製鋼技報／Ｖｏｌ．５２ Ｎｏ．２（Ｓｅｐ．２００２）Ｐ６６−７０などに詳細に記載されている。 Thus, the EBSP method has a wider field of view than the X-ray diffraction method or the electron beam diffraction method using a transmission electron microscope, and can provide various information on hundreds of crystal grains for several hours. There are advantages you can get within. In addition, since the specified region is scanned at a fixed interval instead of the measurement for each crystal grain, there is an advantage that each of the above-mentioned information regarding the above-described many measurement points covering the entire measurement region can be obtained. Details of the crystal orientation analysis method in which the EBSP system is mounted on these FESEMs are described in Kobe Steel Technical Report / Vol. 52 no. 2 (Sep. 2002) P66-70 and the like.
（圧延方向引張時の｛１１−２２｝＜１１−２３＞双晶変形のシュミット因子の平均値）
チタン板の圧延面表面を機械研磨し、更に、バフ研磨に次いで電解研磨を行い、チタン板の表面から深さｔ／４（ｔは板厚）部の圧延面（チタン板の表面に平行な面であって、その板厚方向の深さｔ／４部の面）の結晶組織が観察できるように調整し、その圧延面における圧延方向引張時の｛１１−２２｝＜１１−２３＞双晶変形のシュミット因子の平均値を、前記した測定により得た。測定エリアは１ｍｍ×１ｍｍの平面内とし、測定ピッチは１μｍとした。
(Average value of Schmid factor of {11-22} <11-23> twin deformation during rolling direction tension)
The surface of the rolled surface of the titanium plate is mechanically polished, followed by buffing and electrolytic polishing, and the rolled surface at a depth of t / 4 (t is the thickness) from the surface of the titanium plate (parallel to the surface of the titanium plate). The surface is adjusted so that the crystal structure of the surface (thickness t / 4 part depth in the plate thickness direction) can be observed, and {11-22} <11-23> The average value of the Schmid factor of crystal deformation was obtained by the above-described measurement. The measurement area was in a 1 mm × 1 mm plane, and the measurement pitch was 1 μm.
圧延方向引張時の｛１１−２２｝＜１１−２３＞双晶変形のシュミット因子の平均値は、測定した各測定点のシュミット因子を用いて、シュミット因子が０〜０．１、０．１〜０．２、０．２〜０．３、・・・、４．９〜５．０の区分毎の測定点数を抽出し、以下の式により求めた。 The average value of the Schmid factor of {11-22} <11-23> twin deformation at the time of rolling in the tensile direction is determined using the Schmit factor at each measured measurement point. The number of measurement points for each section of -0.2, 0.2-0.3, ..., 4.9-5.0 was extracted and determined by the following formula.
ここで、iは各区分の中央値、ｋiは各区分の測定点数、ｎは全測定点数である。
Here, i is the median value of each section, k i is the number of measurement points in each section, and n is the total number of measurement points.
＜結晶粒（α相）の平均結晶粒径＞
結晶粒（α相）の平均結晶粒径は、チタン板の圧延面表面を機械研磨し、更に、バフ研磨に次いでエッチングを行い、チタン板の表面から深さｔ／４部の圧延面の結晶組織が観察できるように調整し、光学顕微鏡を用いて×１００にて任意の３箇所を写真撮影し、得られた写真を元にＪＩＳ Ｇ ０５５１の切断法により粒度番号測定を実施し、その粒度番号をもとにα相の円相当平均粒径（直径）を計算により求めた。尚、粒度番号測定に用いた光学顕微鏡による観察領域は１ｍｍ×１ｍｍとした。
<Average crystal grain size of crystal grains (α phase)>
The average crystal grain size of the crystal grains (α phase) is obtained by mechanically polishing the rolled surface of the titanium plate, further etching after buffing, and crystal of the rolled surface at a depth of t / 4 part from the surface of the titanium plate. Adjusted so that the structure can be observed, photographed any three locations at × 100 using an optical microscope, and performed particle size number measurement according to the cutting method of JIS G 0551 based on the obtained photograph. Based on the number, the circle equivalent average particle diameter (diameter) of the α phase was obtained by calculation. In addition, the observation area | region by the optical microscope used for the particle size number measurement was 1 mm x 1 mm.
＜耐力の測定＞
チタン板の耐力については、製造した各チタン板からＪＩＳＺ２２０１に規定される１３号試験片を作製し、この試験片について、ＪＩＳＺ２２４１に準拠する引張試験を行い、試験片の圧延方向の０．２％耐力（ＹＳ）を測定することで求めた。尚、試験片は、その長手方向（Ｌ方向）が圧延方向と一致するようにして採取した。また、試験速度（引張試験での歪み速度）は、０．３ｍｍ／ｍｉｎで一定とした。
<Measurement of yield strength>
Regarding the proof stress of the titanium plate, No. 13 test piece defined in JISZ2201 is prepared from each manufactured titanium plate, a tensile test based on JISZ2241 is performed on this test piece, and 0.2% in the rolling direction of the test piece. It calculated | required by measuring yield strength (YS). In addition, the test piece was extract | collected so that the longitudinal direction (L direction) might correspond with a rolling direction. The test speed (strain speed in the tensile test) was constant at 0.3 mm / min.
この試験で得られた試験片の圧延方向の０．２％耐力（ＹＳ）が２００ＭＰａ以上のものを、高耐力であると評価した。 A test piece obtained in this test having a 0.2% yield strength (YS) in the rolling direction of 200 MPa or more was evaluated as having high yield strength.
＜プレス成形性＞
プレス成形性については、図１に示すような、Ｖ字形の溝を設けたプレート式熱交換器の熱交換部分をプレス成形することを模擬したプレス成形金型を用いてチタン板（試験体）のプレス成形を実施し、その評価を行った。プレス成形金型は、図１に示すように、成形部の大きさが１００ｍｍ×１００ｍｍで、その表面には、ピッチ１０ｍｍ、最大高さ４ｍｍの平面Ｖ字形の平行する稜線部が６本形成されている。その各稜線部のＲ形状は、図１（ａ）の上から下に向かって順に、Ｒ＝０．４、１．８、０．８、１．０、１．４、０．６の計６種類である。
<Press formability>
Regarding press formability, as shown in FIG. 1, a titanium plate (test body) using a press mold that simulates press forming of a heat exchange portion of a plate heat exchanger provided with a V-shaped groove. The press molding was carried out and evaluated. As shown in FIG. 1, the press-molding die has a size of a molding portion of 100 mm × 100 mm, and six parallel V-shaped parallel ridge portions having a pitch of 10 mm and a maximum height of 4 mm are formed on the surface. ing. The R shape of each ridge line portion is a total of R = 0.4, 1.8, 0.8, 1.0, 1.4, 0.6 in order from the top to the bottom of FIG. There are six types.
この成形金型を用いて８０ｔｏｎ油圧プレス機によってプレス成形を実施した。具体的には、各試験体の表裏面に動粘度３４ｍｍ２／ｓ（４０℃）のプレス油を塗布し、各試験体を、その圧延方向（Ｌ方向）が図１（ａ）の上下方向と一致するようにして下金型の上面に配置し、そのフランジ部を板押さえで拘束した後、プレス速度１ｍｍ／ｓ、押し込み深さ４．０ｍｍの条件でプレス成形を実施した。プレス成形性の評価は、プレス成形後に認められる割れの数で評価した。具体的な評価方法を以下に説明する。 Using this molding die, press molding was performed by an 80 ton hydraulic press. Specifically, press oil having a kinematic viscosity of 34 mm 2 / s (40 ° C.) is applied to the front and back surfaces of each test specimen, and the rolling direction (L direction) of each test specimen is the vertical direction in FIG. Was placed on the upper surface of the lower mold so as to coincide with the above, and the flange portion was constrained by a plate press, and then press molding was performed under the conditions of a press speed of 1 mm / s and an indentation depth of 4.0 mm. The press formability was evaluated by the number of cracks observed after press forming. A specific evaluation method will be described below.
プレス成形後の各試験体の図１（ａ）に示す稜線部と、測定位置Ａ、Ｂ、Ｃ、Ｃ´、Ｄ、Ｅの一点鎖線との交点計３６箇所について、割れの有無を目視で観察した。尚、測定位置Ｃ´は、図１（ｂ）に示すように、隣接する稜線部の間に位置する谷部である。 The presence or absence of cracks is visually observed at 36 points of intersection between the ridge line portion shown in FIG. 1A of each test body after press molding and the one-dot chain lines of measurement positions A, B, C, C ′, D, and E. Observed. Note that the measurement position C ′ is a valley portion located between adjacent ridge line portions as shown in FIG.
この目視において、割れの起点となる測定位置Ａ、Ｃ、Ｃ´、Ｅについては、割れもくびれも認められなければ２点、くびれが認められれば１点、割れが認められれば０点とし、他の測定位置Ｂ、Ｄについては、割れもくびれも認められなければ１点、くびれが認められれば０．５点、割れが認められれば０点とし、更にその各点数に加工Ｒの逆数を掛けて割れの状態を数値化し、その合計値を求めた。その合計値を、完全に割れ、くびれが認められない場合を１００として規格化した後、温度（Ｔ）、潤滑油の粘度（μ）、試験体の板厚（ｔ）に依存する関数Ｆ（Ｔ，μ，ｔ）、並びに、プレス金型の稜線の角度（α）、ピッチ（ｐ）に依存する関数Ｇ（α，ｐ）を掛け合わせて、成形性スコアとして算出した。尚、Ｆ並びにＧは０〜１の値である。 In this visual inspection, the measurement positions A, C, C ′, and E, which are the starting points of cracking, are 2 points if neither cracking nor constriction is observed, 1 point if constriction is recognized, 0 point if cracking is recognized, For other measurement positions B and D, 1 point is given if neither cracking nor constriction is observed, 0.5 point if constriction is recognized, 0 point if cracking is observed, and the reciprocal of machining R is added to each point. Multiply it and digitize the state of the cracks and determine the total. After normalizing the total value as 100 when the case where cracks are not completely observed and constriction is observed, the function F () depends on the temperature (T), the viscosity of the lubricating oil (μ), and the plate thickness (t) of the specimen. T, μ, t) and the function G (α, p) depending on the angle (α) and pitch (p) of the ridge line of the press mold were multiplied to calculate the formability score. Note that F and G are values from 0 to 1.
以上の成形性スコアの算出方法は、下記式によって表すことができる。
成形性スコア＝Ｆ×Ｇ×ΣＥ（ｉｊ）／Ｒ（ｊ）／（ΣＡ，Ｃ，Ｃ´，Ｅ ２／Ｒ（ｊ）＋ΣＢ，Ｄ １／Ｒ（ｊ））×１００
この式において、Ａ、Ｃ、Ｃ´、Ｅの場合は、Ｅ（ｉｊ）＝１．０×（割れくびれなし：２、くびれ：１、割れ０）として、また、Ｂ、Ｄの場合は、Ｅ（ｉｊ）＝０．５×（割れくびれなし：２、くびれ：１、割れ０）として算出した。また、本実施例では、温度（Ｔ）、潤滑油の粘度（μ）、試験体の板厚（ｔ）、プレス金型の稜線の角度（α）、およびプレス金型の稜線のピッチ（ｐ）を一定としたため、Ｆ×Ｇを便宜的に１として成形性スコアを算出した。
The calculation method of the above moldability score can be represented by the following formula.
Formability score = F × G × ΣE (ij) / R (j) / (ΣA, C, C ′, E2 / R (j) + ΣB, D 1 / R (j)) × 100
In this equation, in the case of A, C, C ′, E, E (ij) = 1.0 × (no cracking of the neck: 2, necking: 1, cracking 0), and in the case of B and D, E (ij) = 0.5 × (no cracking: 2, necking: 1, cracking 0). In this example, the temperature (T), the viscosity of the lubricating oil (μ), the thickness of the specimen (t), the angle of the ridge line of the press mold (α), and the pitch of the ridge line of the press mold (p ) Was constant, the moldability score was calculated with F × G as 1 for convenience.
この算出した成形性スコアが、７５点以上を◎、５０点〜７５点未満を○、４０点〜５０点未満を△、４０点未満を×とし、◎、○、△をプレス成形性に優れていると評価した。 The calculated formability score is ◎ for 75 or more points, ◯ for 50 to less than 75 points, △ for 40 to less than 50 points, and × for less than 40 points, and ◎, ○, and △ for excellent press formability. It was evaluated.
＜エリクセン値の測定＞
本実施例の試験では、等方的な形状のプレス成形性の評価にエリクセン試験を採用した。製造した各チタン板からＪＩＳＺ２２４７に規定される２号試験片を作製し、この試験片について、ＪＩＳＺ２２４７の規定に準拠するエリクセン試験を実施し、エリクセン値を測定した。尚、試験速度（エリクセン試験でのプレス速度、すなわちプレス工具の変位速度）は、５ｍｍ／ｍｉｎとした。
<Measurement of Erichsen value>
In the test of this example, the Eriksen test was adopted for evaluating the press formability of isotropic shapes. The No. 2 test piece prescribed | regulated to JISZ2247 was produced from each manufactured titanium plate, the Eriksen test based on the prescription | regulation of JISZ2247 was implemented about this test piece, and the Eriksen value was measured. The test speed (press speed in the Eriksen test, that is, the displacement speed of the press tool) was 5 mm / min.
この試験で得られたエリクセン値が９．０以上のものを成形性に優れていると評価した。 Those having an Erichsen value of 9.0 or more obtained in this test were evaluated as having excellent moldability.
以上の試験結果を表１に示す。 The test results are shown in Table 1.
Ｎｏ．２は、ＦｅとＯの含有量が共に上限に近いもの、Ｎｏ．３は、ＦｅとＯの含有量が共に下限に近いものであり、また、Ｎｏ．４は、最終焼鈍の焼鈍温度が上限に近いもの、Ｎｏ．５は、最終焼鈍の焼鈍温度が下限の８３０℃のもの、Ｎｏ．６は、最終焼鈍の焼鈍時間が５００分と比較的長いもの、Ｎｏ．７は、最終焼鈍の焼鈍時間が５分と短いもの、Ｎｏ．８は、最終焼鈍の焼鈍時間が１０００分とＮｏ．６より更に長いものである。また、Ｎｏ．１は、ＦｅとＯの含有量が本発明で規定する要件の中間値のものであり、これらＮｏ．１〜８の成分組成は、全て本発明の要件を満足し、製造条件も好ましい条件である。 No. No. 2 has both Fe and O contents close to the upper limit. No. 3 has both Fe and O contents close to the lower limit. No. 4 is the one where the annealing temperature of the final annealing is close to the upper limit. No. 5 is the one whose final annealing temperature is 830 ° C. which is the lower limit. No. 6 has a relatively long annealing time of 500 minutes, No. 6 No. 7 has a short annealing time of 5 minutes for the final annealing. No. 8 is the final annealing time of 1000 minutes and No. 8. It is longer than 6. No. No. 1 is an intermediate value of the requirements specified by the present invention for the contents of Fe and O. The component compositions 1 to 8 all satisfy the requirements of the present invention, and the production conditions are also preferable conditions.
これに対し、Ｎｏ．９は、ＦｅとＯの含有量が共に上限を超えるもの、Ｎｏ．１０は、ＦｅとＯの含有量が共に下限を下回るもの、Ｎｏ．１１は、最終焼鈍の焼鈍温度が上限より高いもの、Ｎｏ．１２は、最終焼鈍の焼鈍温度が下限より低いものであり、また、Ｎｏ．１３は、最終焼鈍の焼鈍時間が１分と短すぎるもの、Ｎｏ．１４は、Ｏの含有量がＮｏ．１０より更に少ないもの、Ｎｏ．１５は、ＦｅとＯの含有量が共に更に多いものである。 In contrast, no. No. 9 is one in which both Fe and O contents exceed the upper limit. No. 10 is one in which the contents of Fe and O are both lower than the lower limit. No. 11 has an annealing temperature higher than the upper limit of the final annealing. No. 12 has an annealing temperature of the final annealing lower than the lower limit. No. 13 is the one in which the annealing time of the final annealing is too short as 1 minute. No. 14 has an O content of No. 14. No. 10 or less. No. 15 has a higher Fe and O content.
Ｎｏ．１〜７は、圧延方向引張時の｛１１−２２｝＜１１−２３＞双晶変形のシュミット因子の平均値、結晶粒の平均結晶粒径という本発明で規定する要件も全て満足しており、０．２％耐力（ＹＳ）は全て２００ＭＰａ以上であり、プレス成形性の試験結果も○或いは◎で、エリクセン値も９．０以上である。すなわち、Ｎｏ．１〜７のチタン板は、高耐力でプレス成形性に優れたチタン板であるということができる。 No. Nos. 1 to 7 satisfy all the requirements defined in the present invention, such as the average value of the Schmid factor of the {11-22} <11-23> twin deformation and the average crystal grain size of the crystal grains when tensile in the rolling direction The 0.2% proof stress (YS) is all 200 MPa or more, the test result of press formability is ○ or ◎, and the Erichsen value is 9.0 or more. That is, no. It can be said that the titanium plates 1 to 7 are titanium plates having high yield strength and excellent press formability.
また、Ｎｏ．８は、圧延方向引張時の｛１１−２２｝＜１１−２３＞双晶変形のシュミット因子の平均値が本発明で規定する要件を満足しているものの、請求項２で規定する結晶粒の平均結晶粒径は要件を満足していない。その結果、０．２％耐力（ＹＳ）は２００ＭＰａ以上で、エリクセン値も９．０以上という結果を得ることができたが、プレス成形性の試験結果は△で合格判定基準は満足しているものの、Ｎｏ．１〜７よりは劣る結果となった。 No. 8 shows that the average value of the Schmid factor of {11-22} <11-23> twin deformation at the time of rolling in the rolling direction satisfies the requirements defined in the present invention, but the crystal grains defined in claim 2 The average grain size does not meet the requirements. As a result, the 0.2% proof stress (YS) was 200 MPa or more and the Erichsen value was 9.0 or more, but the test result of press formability was Δ and the acceptance criterion was satisfied. Although no. The result was inferior to 1-7.
一方、Ｎｏ．９〜１５は、０．２％耐力（ＹＳ）、プレス成形性、エリクセン値のいずれか一つ以上で合格判定基準を満足しない結果となった。すなわち、本発明で規定する要件から外れるチタン板は、高耐力でプレス成形性に優れるものとはいえないことが分かる。 On the other hand, no. For Nos. 9 to 15, any one or more of 0.2% proof stress (YS), press formability, and Erichsen value did not satisfy the acceptance criteria. That is, it can be seen that a titanium plate that does not meet the requirements defined in the present invention cannot be said to have high yield strength and excellent press formability.
Claims (2)
１／４ｔ（ｔは板厚）部の圧延面における、圧延方向引張時の｛１１−２２｝＜１１−２３＞双晶変形のシュミット因子の平均値が０．４０以上であることを特徴とする高耐力でプレス成形性に優れたチタン板。 In mass%, Fe is contained in 0.04 to 0.06%, O is contained in 0.07 to 0.11%, and the balance is Ti and inevitable impurities,
The average value of the Schmid factor of {11-22} <11-23> twin deformation at the time of rolling in the rolling direction in the 1/4 t (t is the plate thickness) portion is 0.40 or more. Titanium plate with high yield strength and excellent press formability.
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| JPH1030160A (en) * | 1996-07-18 | 1998-02-03 | Sumitomo Metal Ind Ltd | Production of pure titanium sheet excellent in formability and seizure resistance |
| JP2009215601A (en) * | 2008-03-10 | 2009-09-24 | Kobe Steel Ltd | Titanium alloy sheet having high strength and excellent in formability |
| JP2010150607A (en) * | 2008-12-25 | 2010-07-08 | Kobe Steel Ltd | Titanium alloy sheet having high strength and excellent deep drawability, and method for producing the titanium alloy sheet |
| JP2010255085A (en) * | 2009-04-28 | 2010-11-11 | Kobe Steel Ltd | Titanium plate and method for producing titanium plates |
| JP2011026649A (en) * | 2009-07-23 | 2011-02-10 | Kobe Steel Ltd | Titanium sheet with high yield strength and excellent in press formability |
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| JPH1030160A (en) * | 1996-07-18 | 1998-02-03 | Sumitomo Metal Ind Ltd | Production of pure titanium sheet excellent in formability and seizure resistance |
| JP2009215601A (en) * | 2008-03-10 | 2009-09-24 | Kobe Steel Ltd | Titanium alloy sheet having high strength and excellent in formability |
| JP2010150607A (en) * | 2008-12-25 | 2010-07-08 | Kobe Steel Ltd | Titanium alloy sheet having high strength and excellent deep drawability, and method for producing the titanium alloy sheet |
| JP2010255085A (en) * | 2009-04-28 | 2010-11-11 | Kobe Steel Ltd | Titanium plate and method for producing titanium plates |
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