JP2015140478A - Titanium alloy and heat treatment method of the same - Google Patents
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Abstract
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本発明は、粉末法によるチタン合金部材の製造工程における熱処理方法および同熱処理を施したチタン合金部材に係るもので、特に、チタン合金部材の加工性を向上させる熱処理方法に関する。 The present invention relates to a heat treatment method in a manufacturing process of a titanium alloy member by a powder method and a titanium alloy member subjected to the heat treatment, and more particularly to a heat treatment method for improving the workability of the titanium alloy member.
チタン合金は、室温の平衡状態でｈｃｐのα相とｂｃｃのβ相の二相から成り、その割合によってα相からなるα合金、αとβの２相からなる（α＋β）合金、β相からなるβ合金に大別され、様々な機械特性を示す。 Titanium alloys are composed of two phases, an α phase of hcp and a β phase of bcc, in an equilibrium state at room temperature. Depending on the ratio, an α alloy consisting of an α phase, an α and β phase (α + β) alloy, and a β phase It is broadly divided into β alloys and exhibits various mechanical properties.
α相およびβ相の割合はチタン合金の組成及び加工熱処理によって決定される。チタン合金の熱処理の目的は、加工工程で導入された歪みの開放除去、再結晶化、再結晶化に伴い結晶粒径の粒度と分布の制御であり、より安定化した結晶状態を実現することが一般的である。 The proportion of α phase and β phase is determined by the composition of the titanium alloy and the thermomechanical treatment. The purpose of heat treatment of titanium alloy is to control the grain size and distribution of crystal grain size along with the release of strain introduced in the machining process, recrystallization, and recrystallization, and to realize a more stable crystal state. Is common.
特定の条件を満たした場合は、いわゆる時効効果が出現し熱処理に伴う析出相の出現で、チタン合金の強度アップが図れることが期待される。このように、チタン合金では加工熱処理によって組織を変化させることにより性質を広範囲に制御することができると考えられている。 When a specific condition is satisfied, a so-called aging effect appears, and it is expected that the strength of the titanium alloy can be increased by the appearance of a precipitated phase accompanying heat treatment. Thus, it is considered that the properties of titanium alloys can be controlled over a wide range by changing the structure by thermomechanical treatment.
チタン合金の中でもＴｉ−６Ａｌ−４Ｖに代表される（α＋β）型合金は冷間加工性が乏しいため、通常高温での圧延、押出し、鍛造などの加工によって成形が行われている。 Among titanium alloys, (α + β) type alloys represented by Ti-6Al-4V have poor cold workability, and are usually formed by processes such as rolling, extrusion, and forging at high temperatures.
これに対して粉末法により成形された素材については、β変態点（Ｔβ）以下の（α＋β）高温域に加熱後急冷する溶体化処理によってα相をある程度残し大部分をβ相へ逆変態させた後、５００℃付近の（α＋β）低温域で５時間ほど維持する時効処理によって未変態β相からの微細なα相析出により、強度を上げつつ、延性、靱性にも優れた合金を得ることができるという報告がある（例えば、非特許文献１参照）。 On the other hand, the raw material molded by the powder method is reversely transformed into the β phase by leaving the α phase to some extent by solution treatment in which it is heated to (α + β) high temperature range below the β transformation point (T β ) and then rapidly cooled. After that, an alloy excellent in ductility and toughness is obtained by increasing the strength by fine α phase precipitation from the untransformed β phase by aging treatment for about 5 hours in the (α + β) low temperature range around 500 ° C. There is a report that it is possible (see, for example, Non-Patent Document 1).
このような熱処理されたチタン合金の機械特性は引っ張り強さ（ＴＳ）：約１０００ＭＰａ、耐力（ＹＳ）：約９００ＭＰａ（張り強さ（ＴＳ）に対する耐力（ＹＳ）の比率は約９０％）、伸び：約１０％が一般的であり、その高比強度を活かした主要な用途は、宇宙、航空分野で使用される各種構造部材やエンジン部材、ゴルフクラブ等がある。 The mechanical properties of such a heat-treated titanium alloy are tensile strength (TS): about 1000 MPa, yield strength (YS): about 900 MPa (ratio of yield strength (YS) to tensile strength (TS) is about 90%), elongation : About 10% is common, and the main applications utilizing its high specific strength include various structural members, engine members, golf clubs and the like used in the space and aviation fields.
従来技術に記載された処理を行うことにより、加工歪の除去、再結晶化に伴う結晶粒径と粒度の制御が可能であり、材料の延性改善に効果がある。しかしながら、チタン合金の熱処理によってチタン合金の加工性を改善させる、という技術思想はなかった。 By performing the processing described in the prior art, it is possible to remove the processing strain and control the crystal grain size and particle size accompanying recrystallization, which is effective in improving the ductility of the material. However, there was no technical idea of improving the workability of the titanium alloy by heat treatment of the titanium alloy.
チタン合金の種類によっては、熱処理によって延性が退化する場合もあるが、延性低下防止のためには従来技術でも、加熱速度、温度、時間および冷却速度の検討の結果、β変態点（Ｔβ）以上β変態点（Ｔβ）℃＋１００℃未満に２℃／秒以上の加熱速度で加熱し、５分以内保持後、２℃／秒以上で冷却することによって高強度、高靱性、高延性の（α＋β）型チタン合金を得るという技術が開示されている（例えば、特許文献１参照）。 Depending on the type of titanium alloy, the ductility may be deteriorated by heat treatment. However, in order to prevent the ductility from being lowered, the prior art also has a β transformation point (T β ) as a result of examination of the heating rate, temperature, time and cooling rate. The β transformation point (T β ) ° C. + less than 100 ° C. is heated at a heating rate of 2 ° C./second or more, held within 5 minutes, and then cooled at 2 ° C./second or more to achieve high strength, high toughness, and high ductility. A technique for obtaining an (α + β) type titanium alloy is disclosed (see, for example, Patent Document 1).
また、質量％でＣが０．０８％超、０．２５％以下、Ａｌが２．０〜８．５％を含有し、Ｖ、Ｃｒ、Ｆｅ、Ｍｏ、Ｎｉ、Ｎｂ、Ｔａのいずれかを合計で２．０〜１０．０％含有することによって疲労強度に優れた（α＋β）型チタン合金を得るという技術が開示されている（例えば、特許文献２参照）。 Moreover, C contains more than 0.08% by mass%, 0.25% or less, Al contains 2.0 to 8.5%, and any one of V, Cr, Fe, Mo, Ni, Nb and Ta is contained. A technique of obtaining an (α + β) type titanium alloy having excellent fatigue strength by containing 2.0 to 10.0% in total is disclosed (for example, see Patent Document 2).
加工性の改善のためには、高い延性と加工硬化の程度が低いことが望ましいが、熱処理によってこのような状態を実現する技術は、あまり知られていない。 In order to improve the workability, it is desirable that the high ductility and the degree of work hardening be low. However, a technique for realizing such a state by heat treatment is not well known.
一般にチタン合金は冷間または温間での加工性が悪いために、熱間加工で加工された材料を切削加工によって最終形状に加工されるが、材料の製品率悪化、切削工具の寿命悪化等の問題があり、改善が求められている。 In general, titanium alloys have poor workability in cold or warm conditions, so the material processed by hot working is processed into the final shape by cutting, but the product rate of the material deteriorates, the life of the cutting tool deteriorates, etc. There is a problem and improvement is demanded.
本発明は、上記のような問題点の解決を図ったものであり、（α＋β）域において、適切な熱処理を行うことにより、従来に比べて高い伸び（ＥＬ）と引っ張り強さ（ＴＳ）を兼備しつつも耐力（ＹＳ）を低くすることによって従来よりも高い加工性を有するチタン合金の熱処理方法を提供することを目的とする。 The present invention is intended to solve the above-described problems. By performing an appropriate heat treatment in the (α + β) region, the present invention has a higher elongation (EL) and tensile strength (TS) than before. It aims at providing the heat processing method of the titanium alloy which has workability higher than before by reducing a yield strength (YS), combining it.
かかる実情に鑑み前記課題について鋭意検討を進めたところ、所定の熱処理を行ったβ相を主体とするチタン合金であって、該チタン合金中の母相に対するβ相の存在比が５０％〜８０％の範囲にあるチタン合金は、高い強度を示すのみならず、優れた延びを示すことを示すことを見出し、本発明を完成するに至った。 In view of this situation, the above-mentioned problems have been intensively studied. As a result, a titanium alloy mainly composed of a β phase subjected to a predetermined heat treatment, the abundance ratio of the β phase with respect to the parent phase in the titanium alloy is 50% to 80%. It has been found that a titanium alloy in the range of% shows not only high strength but also excellent elongation, and the present invention has been completed.
即ち、本発明に係るチタン合金は、β相を主体とするチタン合金であって、Ｔβをβ変態点とした場合に３．５以上の加工度かつ（Ｔβ−１２０）℃〜Ｔβ℃の温度範囲にて熱間加工したチタン合金を、大気中（Ｔβ−１２０）℃〜Ｔβ℃の温度範囲で６０〜３６０分保持後、急冷したものであり、該チタン合金中の母相に対するβ相の存在比が５０％〜８０％の範囲にあることを特徴とするものである。 That is, the titanium alloy according to the present invention is a titanium alloy mainly composed of a β phase, and when T β is a β transformation point, a workability of 3.5 or more and (T β −120) ° C. to T β the ° C. hot working the titanium alloy at a temperature range of, after holding 60 to 360 minutes in the temperature range of the atmosphere (T β -120) ℃ ~T β ℃, is obtained by rapid cooling, the mother of the titanium alloy The abundance ratio of the β phase to the phase is in the range of 50% to 80%.
また、本発明に係るチタン合金においては、前記チタン合金の降伏強度が引っ張り強度の６０％以下であることを好ましい態様とするものである。 In the titanium alloy according to the present invention, it is preferable that the yield strength of the titanium alloy is 60% or less of the tensile strength.
更には、本発明に係るチタン合金においては、前記チタン合金の引っ張り強度が１２００ＭＰａ以上で、伸びが１５％以上であることを好ましい態様とするものである。 Furthermore, in the titanium alloy according to the present invention, it is preferable that the titanium alloy has a tensile strength of 1200 MPa or more and an elongation of 15% or more.
また、本発明に係るチタン合金においては、前記チタン合金のビッカース硬さが３９０Ｈｖ以下であることを好ましい態様とするものである。 In the titanium alloy according to the present invention, it is preferable that the titanium alloy has a Vickers hardness of 390 Hv or less.
更には、本発明に係るチタン合金においては、前記チタン合金が、ＡｌとＶを含有、さらにＣｕ、Ｆｅ、Ｃｒのいずれか１種類以上の元素を０．５〜４．０％含有することを好ましい態様とするものである。 Furthermore, in the titanium alloy according to the present invention, the titanium alloy contains Al and V, and further contains 0.5 to 4.0% of one or more elements of Cu, Fe, and Cr. This is a preferred embodiment.
本発明に係るチタン合金の熱処理方法は、加工度が３．５以上であり、かつ（Ｔβ−１２０）℃〜Ｔβ℃の温度範囲にて熱間加工したチタン合金を、大気中（Ｔβ−１２０）℃〜Ｔβ℃の温度範囲で６０〜３６０分保持後、急冷することを好ましい態様とするものである。 Heat treatment method of a titanium alloy according to the present invention, the working ratio is not less than 3.5, and a (T β -120) ℃ ~T β ℃ hot working the titanium alloy at a temperature range of, in the air (T It is preferable to rapidly cool after holding for 60 to 360 minutes in a temperature range of β- 120) ° C. to T β ° C.
本発明は前記したような特徴を有するチタン合金に上記熱処理を施すことによって、伸び（ＥＬ）が１５％以上かつ、引っ張り強さ（ＴＳ）が１２００〜１４００ＭＰａと高いが、耐力（ＹＳ）が５００〜７００ＭＰａと低い材料が得られるという効果を奏するものである。 In the present invention, when the titanium alloy having the above-described characteristics is subjected to the heat treatment, the elongation (EL) is 15% or more and the tensile strength (TS) is as high as 1200 to 1400 MPa, but the proof stress (YS) is 500. The effect is that a material as low as ˜700 MPa can be obtained.
本発明の最良の実施形態について以下に詳細に説明する。
本発明に係るチタン合金は、まず、チタン合金粉に必要に応じて添加元素粉末を添加し、熱間押し出し、真空プレスまたはＨＩＰ処理等の緻密化処理によって形成したものであり、続いて、Ｔβをβ変態点とした場合に３．５以上の加工度かつ（Ｔβ−１２０）℃〜Ｔβ℃の温度範囲にて熱間加工したチタン合金を、大気中（Ｔβ−１２０）℃〜Ｔβ℃の温度範囲で６０〜３６０分保持後、急冷するという熱処理を施したβ相を主体とするチタン合金とし、該チタン合金中の母相に対するβ相の存在比が５０％〜８０％の範囲にあることを特徴とするものである。ここで、母相とは、α相とβ相の全体を意味する。ここで本発明における急冷とは、水または油を用いて冷却することを意味する。
The best embodiment of the present invention will be described in detail below.
The titanium alloy according to the present invention is formed by first adding an additive element powder to the titanium alloy powder as necessary, and forming it by densification treatment such as hot extrusion, vacuum press or HIP treatment. 3.5 or more working ratio and when the beta and beta transformation point (T β -120) ℃ ~T β ℃ hot working the titanium alloy at a temperature range of, in the air (T β -120) ℃ 60 to 360 min after maintained in a temperature range of through T beta ° C., and titanium alloys mainly composed of beta phase that has been subjected to the heat treatment of quenching, the abundance ratio of the beta phase to matrix phase of the titanium alloy is 50% to 80 % Range. Here, the parent phase means the entire α phase and β phase. Here, the rapid cooling in the present invention means cooling using water or oil.
ここでβ相を主体とするとは、α相とβ相の混合相からなるチタン合金において結晶組織において面積比率で母相に対するβ相の存在比が５０％〜８０％の範囲に存在していることを好ましい態様とするものである。 Here, the β phase is mainly composed of a titanium alloy composed of a mixed phase of an α phase and a β phase in which the abundance ratio of the β phase with respect to the parent phase is within a range of 50% to 80% in the crystal structure. This is a preferred embodiment.
β相が５０％未満ではα相の増加によるＹＳの上昇によって、ＹＳ／ＴＳ％が高くなり加工が難しくなるという課題が生じる。一方、β相が８０％超では組織の大半をβ相が占めることによりＹＳは低下するが、それ以上にＴＳが大きく低下し、強度が著しく低下するという課題が生じる。よって、本発明に係るチタン合金は、β相を主体とするチタン合金であって、該チタン合金中の母相に対するβ相の存在比が５０％〜８０％の範囲に存在していることを好ましい態様とするものである。 If the β phase is less than 50%, the increase of YS due to the increase of the α phase causes a problem that YS / TS% increases and processing becomes difficult. On the other hand, if the β phase exceeds 80%, the β phase occupies most of the structure, so that YS decreases. However, TS further greatly decreases, and the problem that the strength significantly decreases occurs. Therefore, the titanium alloy according to the present invention is a titanium alloy mainly composed of a β phase, and the abundance ratio of the β phase to the parent phase in the titanium alloy is in the range of 50% to 80%. This is a preferred embodiment.
前記したような結晶構造をとるような合金とすることにより、従来に比べて高い伸びと引っ張り強さを兼備しつつも降伏強度が低く、従来よりも高い加工性を示す、という効果を奏するものである。 By using an alloy having a crystal structure as described above, there is an effect that the yield strength is low and the workability is higher than the conventional one while having both high elongation and tensile strength compared to the conventional one. It is.
また、本発明に係るチタン合金においては、降伏強度が引っ張り強度の６０％以下である、という効果を奏するものである。前記した性質は、最大の引っ張り強度に対して降伏強度が６０％以下であり、これは、チタン合金の延性に優れていることを意味するものである。 Moreover, in the titanium alloy which concerns on this invention, there exists an effect that yield strength is 60% or less of tensile strength. The above properties have a yield strength of 60% or less with respect to the maximum tensile strength, which means that the ductility of the titanium alloy is excellent.
具体的には、チタン合金の引っ張り強度が１２００ＭＰａ以上で、伸びが１５％以上であるという、伸びおよび強度を兼備した優れた特性を有するという、効果を奏するものである。 Specifically, there is an effect that the titanium alloy has excellent properties having both elongation and strength such that the tensile strength of the titanium alloy is 1200 MPa or more and the elongation is 15% or more.
本発明に係るチタン合金においては、ビッカース硬さが３９０Ｈｖ以下であることを好ましい態様とするものであり、一般的に言われているチタン合金に比べて硬度が低く、切削加工性という点で、優れた特性を有するものである。 In the titanium alloy according to the present invention, it is preferable that the Vickers hardness is 390 Hv or less, the hardness is lower than that of a generally-known titanium alloy, and in terms of machinability, It has excellent characteristics.
上記機械特性を満たすことにより、切削工程の生産性が大幅に改善されるとともに、副次的効果として切削作業を行う際のチップの寿命が大幅に延びるという効果を奏するものである。 By satisfying the mechanical characteristics, productivity of the cutting process is greatly improved, and as a secondary effect, there is an effect that the life of the chip when performing the cutting operation is greatly extended.
本発明に係るチタン合金においては、ＡｌとＶを含有し、さらにＣｕ、Ｆｅ、Ｃｒのいずれか１種類以上の元素を０．５〜４．０％含有することを好ましい態様とするものである。 The titanium alloy according to the present invention contains Al and V, and further preferably contains 0.5 to 4.0% of one or more elements of Cu, Fe, and Cr. .
即ち、本発明に係るチタン合金は、いわゆる６Ａｌ４Ｖ合金であって、前記合金中に、更に、Ｃｕ、Ｆｅ、Ｃｒのうち少なくとも１種以上の元素を含んでいることを好ましい態様とするものである。 That is, the titanium alloy according to the present invention is a so-called 6Al4V alloy, and it is preferable that the alloy further contains at least one element of Cu, Fe, and Cr. .
具体的には、Ｃｕ、Ｆｅ、Ｃｒを０．５〜４．０ｗｔ％含むことによってβ相の比率を５０〜８０％に制御することができ、本発明に係る好ましい特性を得ることができる、という効果を奏するものである。 Specifically, by including 0.5 to 4.0 wt% of Cu, Fe, and Cr, the ratio of β phase can be controlled to 50 to 80%, and preferable characteristics according to the present invention can be obtained. This is an effect.
その結果、前記したような延性および強度の優れた特性を有するチタン合金を選択することができる、という効果を奏するものである。 As a result, there is an effect that a titanium alloy having excellent properties such as ductility and strength as described above can be selected.
本発明に係るチタン合金の熱処理方法は、加工度が３．５で、かつ（Ｔβ−１２０）℃〜Ｔβ℃の温度範囲にて熱間加工したチタン合金を、大気中（Ｔβ−１２０）℃〜Ｔβ℃の温度範囲で６０〜３６０分保持後、急冷することを好ましい態様とするものである。ここでいうところの加工度とは、（加工前試料の断面積）／（加工後試料の断面積）で定義される。 Heat treatment method of a titanium alloy according to the present invention, the working ratio of 3.5, and a (T β -120) ℃ ~T β ℃ hot working the titanium alloy at a temperature range of, in the air (T beta - after 60 to 360 minutes holding the temperature range of 120) ℃ ~T β ℃, it is an preferred embodiment the quenching. The degree of processing here is defined as (cross-sectional area of the sample before processing) / (cross-sectional area of the sample after processing).
前記熱間加工温度が、（Ｔβ−１２０）℃未満では変形抵抗が設備能力を上回り加工不可となる場合がある。また、材料に過大な負荷がかかるために加工時のクラック発生の原因ともなりうる。一方、Ｔβ℃超では粗大なβ粒子の発生によって延性が低下する。よって、本発明に係る熱間加工温度は、（Ｔβ−１２０）℃〜Ｔβ℃の範囲が好ましい、とされる。 The hot working temperature, there is a case where deformation resistance is processed not exceed the production capacity is less than (T β -120) ℃. Further, since an excessive load is applied to the material, it may cause cracks during processing. On the other hand, if it exceeds T β ° C, the ductility decreases due to the generation of coarse β particles. Accordingly, hot working temperature according to the present invention, the range of (T β -120) ℃ ~T β ℃ preferred, are.
前記熱間加工後の大気中での保持温度が、（Ｔβ−１２０）℃未満では母相に対するβ相の存在比が５０％未満となり、延性が低下する。一方、Ｔβ℃超では粗大なβ粒子の発生によって延性が低下する。よって、本発明に係る大気中での保持温度は、（Ｔβ−１２０）℃〜Ｔβ℃の範囲が好ましい、とされる。本発明においてＴβは、９２０℃と定義するものとする。 Holding temperature in air after the hot working, the presence ratio of beta phase to matrix phase is less than (T β -120) ℃ becomes less than 50%, the ductility is reduced. On the other hand, if it exceeds T β ° C, the ductility decreases due to the generation of coarse β particles. Therefore, the holding temperature in an atmosphere according to the present invention, the range of (T β -120) ℃ ~T β ℃ preferred, are. T beta in the present invention shall be defined as 920 ° C..
また、本発明においては、前記大気中での保持でのチタン合金の保持時間は６０〜３６０分が好ましいとされる。 In the present invention, the holding time of the titanium alloy in the holding in the atmosphere is preferably 60 to 360 minutes.
前記保持時間が６０分未満では、チタン合金の均熱がとれず、チタン合金中のα相とβ相の存在比に偏りが発生し、α相の存在比が高い部分を起点として破断を起こしやすくなる。一方、前記保持時間が、３６０分超では、長時間の加熱により粒子が粗大化し延性が低下する。よって、本発明に係るチタン合金の熱処理時間は、６０〜３６０分が、好ましい、とされる。 When the holding time is less than 60 minutes, the soaking of the titanium alloy cannot be achieved, the abundance ratio of the α phase and the β phase in the titanium alloy is generated, and the fracture starts from the portion where the abundance ratio of the α phase is high. It becomes easy. On the other hand, when the holding time exceeds 360 minutes, the particles become coarse due to heating for a long time and the ductility decreases. Therefore, the heat treatment time of the titanium alloy according to the present invention is preferably 60 to 360 minutes.
本発明においては、前記熱処理後、急冷することを好ましい態様とするものである。急冷によって、熱間でのβリッチな状態を常温まで持ち来たすことで、優れた伸びを得ることができる、という効果を奏するものである。 In the present invention, it is preferable to rapidly cool after the heat treatment. By bringing the β-rich state in the hot state to room temperature by rapid cooling, it is possible to obtain an excellent elongation.
ここで、急冷による材料表面での冷却速度は、１０〜３００℃／秒が好ましく、 ２０〜２００℃／秒をより好ましい態様とするものである。材料の内部温度は材料表面の冷却媒体からの徐熱と材料内部の熱伝導に従う。 Here, the cooling rate on the material surface by rapid cooling is preferably 10 to 300 ° C./second, and more preferably 20 to 200 ° C./second. The internal temperature of the material follows the slow heat from the cooling medium on the surface of the material and the heat conduction inside the material.
前記したような加工度を有するチタン合金を前記した温度範囲で熱処理し、その後、水冷処理することにより、高い強度を示すのみならず、延性にも優れたチタン合金を製造することができる、という効果を奏するものである。 By heat-treating the titanium alloy having the workability as described above in the temperature range described above, and then performing water cooling treatment, it is possible to produce a titanium alloy that not only exhibits high strength but also has excellent ductility. There is an effect.
ここで、本発明に係るチタン合金は、チタン合金粉に対して、目的とする合金組成になるように各種金属粉末をブレンドした後、緻密化処理して焼結体を得た後、次いで、同焼結体に塑性加工を加えてから熱処理することを好ましい態様とするものである。 Here, the titanium alloy according to the present invention is a titanium alloy powder, after blending various metal powders so as to have a target alloy composition, after densifying to obtain a sintered body, A preferred embodiment is to heat-treat the sintered body after plastic working.
前記したような塑性加工の塑性歪みは、３．５〜２５の範囲とすることが好ましい。前記した範囲に塑性歪を付与させることにより、その後行う熱処理により効率よく結晶粒の微細化を進めることができる、という効果を奏するものである。 The plastic strain of the plastic working as described above is preferably in the range of 3.5-25. By applying plastic strain to the above-described range, it is possible to efficiently refine the crystal grains by a subsequent heat treatment.
以上、前記したように、本発明に係るチタン合金は、引っ張り強度のみならず、すぐれた延性を示す、という効果を奏するものである。 As described above, the titanium alloy according to the present invention has an effect of exhibiting not only tensile strength but also excellent ductility.
以下、実施例および比較例によって本発明をさらに具体的に説明する。
実施例で使用した設備および条件を以下に列記する。
１．チタン合金粉
１）原料：チタン６４合金の切削切粉
２）チタン合金粉：ＨＤＨ法により製造
３）粒度：１０μｍ〜２５０μｍ
２．添加元素粉末
１）添加元素：銅
２）平均粒径：約６μｍ
３）添加量：０．５〜４．０ｗｔ％
３．緻密化処理
１）手段：熱間押し出し、真空プレスまたはＨＩＰ処理
２）緻密化温度：９００℃〜９３０℃
４．塑性加工
１）手段
熱間圧延 圧延比：３．５〜２５
熱間鍛造 鍛造比：３．５〜２８
２）加工温度：８５０Ｃ°〜８９０Ｃ°
５．熱処理
前記塑性加工処理を施したチタン材に対して焼鈍処理を進めた。
１）温度：８５０Ｃ°〜９００Ｃ°
２）雰囲気：大気雰囲気
３）昇温速度：１５℃／分
４）保持時間：６０〜３６０分
５）冷却方法：水冷または油冷
Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples.
The equipment and conditions used in the examples are listed below.
1. Titanium alloy powder 1) Raw material: Cutting chips of titanium 64 alloy 2) Titanium alloy powder: produced by HDH method 3) Particle size: 10 μm to 250 μm
2. Additive element powder 1) Additive element: Copper 2) Average particle size: about 6 μm
3) Addition amount: 0.5 to 4.0 wt%
3. Densification treatment 1) Means: hot extrusion, vacuum press or HIP treatment 2) Densification temperature: 900 ° C. to 930 ° C.
4). Plastic working 1) Means Hot rolling Rolling ratio: 3.5-25
Hot forging Forging ratio: 3.5-28
2) Processing temperature: 850C-890C °
5. Heat treatment An annealing treatment was performed on the titanium material subjected to the plastic working treatment.
1) Temperature: 850C-900C
2) Atmosphere: Air atmosphere 3) Rate of temperature increase: 15 ° C./min 4) Holding time: 60 to 360 minutes 5) Cooling method: water cooling or oil cooling
［実施例１］
上記のチタン合金粉を原料とし、これをカプセルに入れて熱間押出しにより緻密化を行なった。緻密化処理された前記チタン焼結体を熱間圧延して、径９．５ｍｍの棒材を得た。得られた棒材に８７０℃で６０分保持後水冷という熱処理を行った同棒材の結晶組織を調査したところ、母相に対するβ相の結晶組織の比率は６０％であった。当該チタン合金の機械特性は、ＥＬ：２１．４％、ＴＳ：１２８６ＭＰａ、ＹＳ：５２６ＭＰａであり、ＹＳがＴＳの４１％であった。また、ビッカース硬さは３７５Ｈｖであった。
[Example 1]
The above titanium alloy powder was used as a raw material, which was put into a capsule and densified by hot extrusion. The densified titanium sintered body was hot-rolled to obtain a bar having a diameter of 9.5 mm. When the crystal structure of the bar material obtained by subjecting the obtained bar material to a heat treatment of holding at 870 ° C. for 60 minutes and then water cooling was investigated, the ratio of the β phase crystal structure to the parent phase was 60%. The mechanical properties of the titanium alloy were EL: 21.4%, TS: 1286 MPa, YS: 526 MPa, and YS was 41% of TS. The Vickers hardness was 375 Hv.
［実施例２］
実施例１で使用したチタン合金材の加工温度や加工度および焼鈍温度を種々変更して、母相に対するβを種々変更して、それぞれの際に得られたチタン合金材のＹＳ／ＴＳ及びビッカース硬さに及ぼす影響を調査し、その結果を表１に示した。表１の結果より、本発明に係るチタン合金の製造方法に係る母相に対するβ相の結晶組織の比率は５０〜８０％が好ましい範囲であることが確認された。
[Example 2]
Various changes were made in the processing temperature, processing degree, and annealing temperature of the titanium alloy material used in Example 1, and various changes were made to β relative to the parent phase. YS / TS and Vickers of the titanium alloy material obtained in each case The effect on hardness was investigated, and the results are shown in Table 1. From the results in Table 1, it was confirmed that the ratio of the crystal structure of the β phase to the parent phase according to the method for producing a titanium alloy according to the present invention is in a preferable range of 50 to 80%.
［実施例３］
実施例１で使用したチタン合金材に添加する銅粉末の添加量を種々変更して、それぞれの際に得られた母相に対するβ相の結晶組織の比率を調査し、その結果を表２に示した。表２の結果より、本発明に係るチタン合金の製造方法に係る添加する銅粉末の添加量は０．５〜４．０ｗｔ％が好ましい範囲であることが確認された。
[Example 3]
Various changes were made in the amount of copper powder added to the titanium alloy material used in Example 1, and the ratio of the crystal structure of the β phase to the parent phase obtained in each case was investigated. Indicated. From the results of Table 2, it was confirmed that the addition amount of the copper powder to be added according to the method for producing a titanium alloy according to the present invention is in a preferable range of 0.5 to 4.0 wt%.
［実施例４］
実施例１で使用したチタン合金材に添加する鉄粉末の添加量を種々変更して、それぞれの際に得られた母相に対するβ相の結晶組織の比率を調査し、その結果を表３に示した。表３の結果より、本発明に係るチタン合金の製造方法に係る添加する鉄粉末の添加量は０．５〜４．０ｗｔ％が好ましい範囲であることが確認された。
[Example 4]
The amount of iron powder added to the titanium alloy material used in Example 1 was variously changed, and the ratio of the crystal structure of the β phase to the parent phase obtained in each case was investigated. The results are shown in Table 3. Indicated. From the results of Table 3, it was confirmed that the amount of iron powder added according to the method for producing a titanium alloy according to the present invention is in a preferred range of 0.5 to 4.0 wt%.
［実施例５］
実施例１で使用したチタン合金材に添加するクロム粉末の添加量を種々変更して、それぞれの際に得られた母相に対するβ相の結晶組織の比率を調査し、その結果を表４に示した。表４の結果より、本発明に係るチタン合金の製造方法に係る添加する銅粉末の添加量は０．５〜４．０ｗｔ％が好ましい範囲であることが確認された。
[Example 5]
Various changes were made in the amount of chromium powder added to the titanium alloy material used in Example 1, and the ratio of the crystal structure of the β phase to the parent phase obtained in each case was investigated. The results are shown in Table 4. Indicated. From the results of Table 4, it was confirmed that the amount of copper powder added according to the method for producing a titanium alloy according to the present invention is in a preferred range of 0.5 to 4.0 wt%.
［実施例６］
実施例１で使用したチタン合金材の加工温度や加工度および焼鈍温度を種々変更し、熱処理温度を種々変更して、それぞれの際に得られたチタン合金材のＹＳ／ＴＳ及びビッカース硬さを調査し、その結果を表５に示した。表５の結果より、本発明に係るチタン合金の製造方法に係る熱処理温度は（Ｔβ−１２０）〜Ｔβが好ましい範囲であることが確認された。
[Example 6]
Various changes were made in the processing temperature, degree of processing and annealing temperature of the titanium alloy material used in Example 1, the heat treatment temperature was changed in various ways, and the YS / TS and Vickers hardness of the titanium alloy material obtained in each case were changed. The results are shown in Table 5. From the results of Table 5, the heat treatment temperature according to the method for manufacturing a titanium alloy according to the present invention was confirmed to be the preferred range (T β -120) ~T β.
［実施例７］
実施例１において冷却方法を水冷から油冷に変更した以外は同じ条件でチタン合金材のＹＳ／ＴＳ及びビッカース硬さに及ぼす影響を調査し、その結果を表６に示した。表６の結果より、本発明に係るチタン合金の製造方法に係る母相に対するβ相の結晶組織の比率は５０〜８０％が好ましい範囲であることが確認された。
[Example 7]
The effect of the titanium alloy material on YS / TS and Vickers hardness was investigated under the same conditions except that the cooling method was changed from water cooling to oil cooling in Example 1, and the results are shown in Table 6. From the result of Table 6, it was confirmed that the ratio of the crystal structure of the β phase to the parent phase according to the method for producing a titanium alloy according to the present invention is in a preferable range of 50 to 80%.
［比較例１］
実施例１において、冷却方法が空冷であることを除き、母相に対するβ相の結晶組織の比率が、６０％であるチタン合金を製造し、これに対する引っ張り強度および伸びを調べた。当該チタン合金の機械特性は、ＴＳ：１３３４ＭＰａ、ＹＳ：１２０２ＭＰａ、ＥＬ：９．４％であり、ＹＳがＴＳの９０％であった。また、ビッカース硬さは４５２Ｈｖであった。実施例１と比較すると、ＹＳ／ＴＳは９０％と高く、伸びについては劣っていた。
[Comparative Example 1]
In Example 1, except that the cooling method was air cooling, a titanium alloy in which the ratio of the β phase crystal structure to the parent phase was 60% was manufactured, and the tensile strength and elongation with respect to this were examined. The mechanical properties of the titanium alloy were TS: 1334 MPa, YS: 1202 MPa, EL: 9.4%, and YS was 90% of TS. The Vickers hardness was 452 Hv. Compared with Example 1, YS / TS was as high as 90%, and the elongation was inferior.
本発明に係るα＋β型チタン合金は、ＹＳが低く、機械的強度を要求される用途には適さないが、人工骨、人工歯根等のインプラント材料やゴルフヘッドや野球用バットに代表されるスポーツ用品、更には、輸送機器用のばねに代表されるサスペンションへの応用が期待される。
The α + β-type titanium alloy according to the present invention has a low YS and is not suitable for applications requiring mechanical strength, but sports equipment represented by implant materials such as artificial bones and artificial roots, golf heads, and baseball bats. Furthermore, application to suspensions represented by springs for transportation equipment is expected.
Claims (6)
Ｔβをβ変態点とした場合に３．５以上の加工度かつ（Ｔβ−１２０）℃〜Ｔβ℃の温度範囲にて熱間加工したチタン合金を、大気中（Ｔβ−１２０）℃〜Ｔβ℃の温度範囲で６０〜３６０分保持後急冷したものであり、
該チタン合金中の母相に対するβ相の存在比が５０％〜８０％の範囲にあることを特徴とするチタン合金。 a titanium alloy mainly composed of β phase,
3.5 or more working ratio and when the T beta was beta transformation point (T β -120) ℃ ~T β ℃ hot working the titanium alloy at a temperature range of, in the air (T beta -120) ° C. in a temperature range of through T beta ° C. is obtained by rapid cooling after 60 to 360 minutes holding,
A titanium alloy characterized in that the abundance ratio of the β phase to the parent phase in the titanium alloy is in the range of 50% to 80%.
A heat treatment method of a titanium alloy according to any one of claims 1 to 5, when the T beta and beta transus, 3.5 or more working ratio and (T beta -120) of ° C. through T beta ° C. hot working the titanium alloy in a temperature range 60 to 360 minutes after holding at a temperature in the range of atmospheric (T β -120) ℃ ~T β ℃, the heat treatment method of a titanium alloy, characterized by rapidly cooling.
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