JP4002213B2

JP4002213B2 - Shape memory alloy material having high shape recoverability and high transformation temperature and method for producing the same

Info

Publication number: JP4002213B2
Application number: JP2003161757A
Authority: JP
Inventors: 真人浅井; 宏堀川; 豊延田中
Original assignee: THE FURUKAW ELECTRIC CO., LTD.; Furukawa Techno Material Co Ltd
Current assignee: THE FURUKAW ELECTRIC CO., LTD.; Furukawa Techno Material Co Ltd
Priority date: 2003-06-06
Filing date: 2003-06-06
Publication date: 2007-10-31
Anticipated expiration: 2023-06-06
Also published as: JP2004360033A

Description

【０００１】
【発明の属する技術分野】
本発明は、マルテンサイト逆変態終了温度（以下Ａｆ温度と略す）が１００℃以上、且つ温度を駆動源とする形状記憶効果または外力を駆動源とする超弾性における完全に回復する形状回復伸び量が、２％以上の形状記憶合金材およびその製造方法に関するものである。
【０００２】
【従来技術】
Ｎｉ−Ｔｉ系の形状記憶合金は、熱弾性型マルテンサイト変態により形状記憶効果および超弾性を示す。この熱弾性型マルテンサイト変態は、マルテサイト変態開始温度（以下Ｍｓ温度と略す）、マルテンサイト変態終了温度（以下Ｍｆ温度と略す）、マルテンサイト逆変態開始温度（以下Ａｓ温度と略す）、そして前記Ａｆ温度の４つの変態温度により、形状記憶合金の利用を支配しているが、良好な形状回復性を示し、且つ変態温度が１００℃以上のＮｉ−Ｔｉ系の形状記憶合金はなく、形状記憶合金の需要拡大の壁となっている。
【０００３】
１００℃以上の変態温度の実現には、第３元素の添加による方法が提案されていて、（１）Ｐｄ元素の添加、（２）Ｈｆ元素、Ｚｒ元素の添加（例えば特許文献１、２、３、４参照）が知られている。
【０００４】
前記（２）の特許文献１では、変態温度に対する合金組成の影響が示されているが、それは鋳塊の変態温度であり、実際に使用される冷間加工材を形状記憶熱処理した材料の変態温度とは異なる。更に、当業者が実施可能な製造法についての開示がない。
【０００５】
一方、特許文献２では、Ｎｉ−Ｔｉ−Ｈｆ合金に関する変態温度の変化（例えば図１、図２、図４、図５）、硬さの変化（例えば図３）、引張強度の変化（例えば図６）が述べられている。また、Ｚｒ元素を８ｍｏｌ％まで含有した時のＮｉ−Ｔｉ−Ｚｒ合金の変態温度挙動（例えば図７）が示されている。更に、1回の減面率が１５％以下の熱間加工によるＮｉ−Ｔｉ−Ｈｆ合金の製造方法が開示されている。
【０００６】
特許文献３では、冷間加工を容易にするためにＢの添加を行い、Ｂ元素未添加のＮｉ−Ｔｉ−Ｚｒ合金は、熱間鍛造プレス中に割れを生じているが、Ｂ元素を含有したＮｉ−Ｔｉ−Ｚｒ−Ｂ合金は、熱間鍛造プレスで割れを発生することなく、線径１ｍｍの線材が得られている。
【０００７】
特許文献４では、Ｎｉ−Ｔｉ−Ｚｒ合金を軟鋼で被覆することで、その熱間加工性を向上させているが、無被覆の場合には、熱間による据え込み鍛造法では割れを生じてしまうとある。
【０００８】
【特許文献１】
特開平３−７２０４６号公報
【特許文献２】
特開平５−４３９６９号公報
【特許文献３】
特開平１０−８１６８号公報
【特許文献４】
特開平１０−３６９５２号公報
【非特許文献１】
舟久保煕康編、「形状記憶合金」、初版、産業図書株式会社、１９８４年６月７日、Ｐ．１５８
【０００９】
【発明が解決しようとする課題】
特許文献１〜４で示される前記従来技術では、本発明に係る合金の成分組成と重複する範囲で、Ａｆ温度が１００℃以上となることが示されている。
しかしながら、形状記憶合金を工業上利用する場合、温度を駆動源とする形状記憶効果と外力を駆動源とする超弾性の両形状回復性が、工業上の利用レベルで得られるのかどうかが重要となるが、特許文献１〜４では、前記形状回復性が、全く判らないという問題がある。特に、具体的な製造条件により合金を作製している特許文献２では、形状回復性の開示が期待されるが、応力とひずみの関係が示されているだけで、形状回復性に関しては明らかでない。
【００１０】
ところで、形状記憶効果および超弾性の両形状回復性が成分組成と製造方法の両者、特に製造方法に大きく依存していることはよく知られている。特に良好な形状回復性を得るには、合金がすべり変形をし難いように、すべり変形に対する高い臨界応力を有することが必要である。
【００１１】
そこで、本発明は前記形状回復性が欠如している１００℃以上のＡｆ温度を有するＮｉ−Ｔｉ−Ｚｒ合金またはＮｉ−Ｔｉ−Ｚｆ−Ｈｆ合金において、その形状回復性を体現化し、工業上の利用において有用な形状記憶合金材とその製造方法の提供を目的とする。
具体的には、工業上の利用レベルにある２％以上の完全に回復する形状回復伸び量を示す形状記憶効果または超弾性を有し、且つ１００℃以上のＡｆ温度を示す高形状回復性および高変態温度を有する形状記憶合金材およびその製造方法である。
【００１２】
【課題が解決するための手段】
請求項１記載の発明は、Ｎｉを４９．５〜５０．２５ｍｏｌ％、Ｚｒを８〜２０ｍｏｌ％含み、残部Ｔｉと不可避不純物とからなる形状記憶合金であって、形状記憶効果または超弾性における完全に回復する形状回復伸び量が２％以上、且つマルテンサイト逆変態終了温度が１００℃以上の高形状回復性および高変態温度を有する形状記憶合金材である。
【００１３】
請求項２記載の発明は、Ｎｉを４９．５〜５０．２５ｍｏｌ％、Ｚｒを８〜２０ｍｏｌ％含み、Ｈｆを０．１ｍｏｌ％未満含み、残部Ｔｉと不可避不純物とからなる形状記憶合金であって、形状記憶効果または超弾性における完全に回復する形状回復伸び量が２％以上、且つマルテンサイト逆変態終了温度が１００℃以上の高形状回復性および高変態温度を有する形状記憶合金材である。
【００１４】
請求項３記載の発明は、Ｎｉ−Ｔｉ系合金に、熱間加工、冷間加工（中間焼鈍を含む）、形状記憶熱処理を施す形状記憶合金材の製造方法において、前記熱間加工を第1と第２に分けて行い、前記第１の熱間加工を押出し法により８８０℃〜１０３０℃の温度で、少なくとも１回以上、累積減面率が４０％以上で行い、引き続き第２の熱間加工を６００℃〜８３０℃の温度で行うことを特徴とする請求項１または請求項２記載の高形状回復性および高変態温度を有する形状記憶合金材の製造方法である。
【００１５】
請求項４記載の発明は、Ｎｉ−Ｔｉ系合金に、熱間加工、冷間加工（中間焼鈍を含む）、形状記憶熱処理を施す形状記憶合金材の製造方法において、前記熱間加工を第１と第２に分けて行い、前記第１の熱間加工を押出し法により８８０℃〜１０３０℃の温度で、少なくとも１回以上、累積減面率が４０％以上で行い、その後、冷却して常温近辺に保持した後、６００℃〜８３０℃に加熱して第２の熱間加工を行うことを特徴とする請求項１または請求項２記載の高形状回復性および高変態温度を有する形状記憶合金材の製造方法である。
【００１６】
請求項５記載の発明は、Ｎｉ−Ｔｉ系合金に、熱間加工、冷間加工（中間焼鈍を含む）、形状記憶処理を施す形状記憶合金材の製造方法において、前記冷間加工（中間焼鈍を含む）が、中間焼鈍と常温状態での加工による減面処理からなり、前記中間焼鈍は、温度と時間の関係が（ａ）６８０℃×１０分、（ｂ）６８０℃×１８０分、（ｃ）８２０℃×３０分、（ｄ）８２０℃×２分の４条件を、（ａ）、（ｂ）、（ｃ）、（ｄ）の順に結んでできる温度―時間平面の平行四辺形の範囲内（線上または内側）の温度・保持時間に相当する組み合わせの条件で行われ、前記中間焼鈍後、１回の加工率が７〜１５％前記中間焼鈍後、１回の加工率が７〜１５％、且つ、中間焼鈍間の累積加工率を２０〜４０％で減面処理することを特徴とする請求項１または請求項２記載の高形状回復性および高変態温度を有する形状記憶合金材の製造方法である。
【００１７】
請求項６記載の発明は、Ｎｉ−Ｔｉ系合金に、熱間加工、冷間加工（中間焼鈍を含む）、形状記憶処理を施す形状記憶合金材の製造方法において、前記形状記憶処理は仕上げ冷間加工とそれに続く熱処理からなり、前記仕上げ冷間加工を累積減面率で２５％以上、１パスあたりの減面率で７％〜１５％の範囲で行い、次いで、５５０℃〜８２０℃の温度で、５分〜１２０分間熱処理することを特徴とする請求項１または請求項２記載の高形状回復性および高変態温度を有する形状記憶合金材の製造方法である。
【００１８】
【発明の実施の形態】
本発明に係る合金材及びその製造方法について、以下に、その実施の形態を説明する。
先ず、本発明において、完全に回復する形状回復伸び量を２％以上に規定した根拠は、形状記憶合金が変形する場合、形状記憶効果では線形の可逆挙動を示す変形は、伸び量で１％未満であり、超弾性の場合では線形の可逆挙動を示す変形は、伸び量で１〜１．５％（例えば非特許文献１を参照）である。即ち、非線形の可逆挙動である形状記憶効果や超弾性を工業上で利用する場合、前記線形の可逆挙動を示す伸び量より大きい形状回復性が要求されることになる。そこで、工業上の利用レベルとして完全に回復する形状回復伸び量を２％以上とした。
【００１９】
次に、１００℃以上のＡｆ温度を有し、良好な形状回復性を得て、更に容易に製造するために、Ｎｉは４９．５〜５０．２５ｍｏｌ％、Ｚｒは８〜２０ｍｏｌ％とした。
Ｎｉが４９．５ｍｏｌ％未満では、Ａｆ温度の上昇には殆ど寄与せず、Ｎｉに対するＴｉの比率をいたずらに増加させることで、加工性を極めて低下させてしまう。５０．２５ｍｏｌ％を超えての含有は、Ｚｒ含有にもかかわらず、Ａｆ温度を１００℃以上にできず、逆に大きく低下させてしまうために限定したものである。
【００２０】
Ｚｒが８ｍｏｌ％未満では、１００℃以上のＡｆ温度が安定して得られなくなり、２０ｍｏｌ％を超えると、溶解鋳造性や加工性が低下し、健全な合金材が得られなくなるためである。
【００２１】
ところで、ＺｒとＨｆは原子周期律上、同じ第２族に属しており、Ｚｒ原料からＨｆを完全に分離することは難しく、一般のＺｒ原料中には、１〜２ｍａｓｓ％のＨｆを含んでいる。そのため本発明では、形状記憶合金をＨｆの少ないＺｒ原料を選別して製造するが、Ｈｆの含有量が０．１ｍｏｌ％以上になるとＡｆ温度の制御が難しくなるために０．１ｍｏｌ％未満が望ましい。
【００２２】
本発明に係る製造方法は、前記組成のＮｉ−Ｔｉ−Ｚｒ合金またはＮｉ−Ｔｉ−Ｚｒ−Ｈｆ合金が、２％以上の完全に回復する形状回復伸び量を有するには、前記合金鋳塊を高温下で十分に加工することが必要であることを見出しなされたものである。
【００２３】
この高温下での加工（熱間加工）は、冷間加工および形状回復性に悪影響を与える鋳塊組織を消滅させるために行うが、当該成分組成の合金鋳塊は応力に対する異方性が強いため、その加工法として、特に第１の熱間加工では断面が全方向に拘束される押出し法が適している。
【００２４】
本発明において第１の熱間加工を８８０℃〜１０３０℃に加熱保持した後に、押出し法により、少なくとも１回以上、累積減面率が４０％以上で加工する理由を次に述べる。
８８０℃未満では、加工に要する力が過大となり加工装置の破損を招く恐れがあると共に十分に鋳塊組織を壊すことができず、良好な加工性と特性を示す材料が得られない。１０３０℃を超えると、加工は容易になるが表面酸化の影響が極めて大きくなり、次に行う第２の熱間加工時や冷間加工時に材料破断の基点となりやすくなる上、場合によっては一部溶解現象が起こり、本熱間加工時に割れが生じ、加工不能となるからである。
【００２５】
累積減面率を４０％以上に限定した理由は、４０％未満の累積減面率では、十分に鋳塊組織を変化させて加工組織化することができず、次工程以下で割れや形状の制御が不十分となり、良好な特性を持つ材料が作製できないためである。なお、累積減面率が８０％を超えてくると加工がし難くなるために、累積加工率は、５０％から８０％の間が望ましい。
【００２６】
なお、拘束面が上下面に限定される鍛造法および緩い拘束下で加工速度の速い圧延法などの加工法では、加工初期に割れを生じて加工不能となる。又、特許文献２に記載の鋳塊の熱間加工法である５〜１５％程度の小さい減面率で、加熱と熱間加工を繰り返し行い、鋳塊を薄くしていく方法では、鋳塊厚さを減ずることは可能であるが、鋳塊組織を均質な加工組織化することは難しく、良好な形状回復性が得られない。更に、繰り返し行われる高温の熱処理によって、合金表面に脆い酸化層が厚く形成して、以降の工程での加工割れを誘引する結果となる。
【００２７】
前記第１の熱間加工を行った合金材は、次に、第２の熱間加工により細径化または薄板化を進めるが、前記第２の熱間加工は第１の熱間加工に続けても、また一旦合金材を冷却してから再度加熱して行ってもよく、本発明の範囲内においては、その加工性にあまり変化はなく、いずれも良好な特性を持つ合金材を得ることができる。なお、第１、第２の熱間加工を続けて行うと生産性の向上および熱エネルギーの低減がはかれる。
【００２８】
第２の熱間加工を６００〜８３０℃に限定する理由は、前記範囲外の低い温度では、変形抵抗が大きくなり、割れの発生や所定の減面率が得られず、生産性の低下を招いてしまう。高い場合には、加工時に合金材内部の温度が上昇し、中心部から割れる芯割れが発生するためである。
前記第２の熱間加工における１回の加工における減面率は、７％以上、望ましくは、１０〜３０％の減面率がよい。
【００２９】
次に、前記第１、第２の熱間加工を施した合金材は、中間焼鈍を含む冷間加工で減面処理することで、所定寸法への加工および良好な形状回復性を有するための組織の均質化が行われる。
前記中間焼鈍は焼鈍温度と時間との関係が、（ａ）６８０℃×１０分、（ｂ）６８０℃×１８０分、（ｃ）８２０℃×３０分、（ｄ）８２０℃×２分で囲まれた範囲内の条件で焼鈍するのが良い。
【００３０】
前記冷間加工における１パスあたりの減面率を７％〜１５％としたのは、７％未満では、中心部まで十分に加工されず異方性の大きな材料となって、加工時の破断の原因となり、また良好な形状が得られない。１パスあたりの減面率が１５％を超えると割れが発生する。従って、７％から１５％の範囲の減面率がよい。中間焼鈍間の累積減面率を２０％〜４５％に限定する理由は、２０％未満では、いたずらに焼鈍回数が増えるばかりで生産性があがらず、コスト上昇の一因ともなり、４５％を超えると加工が難しくなり、１パスあたりの減面率が７％未満になり割れが発生してくるからである。
なお、前記冷間加工に鋳塊のＡｆ温度より１０〜３０℃高い温度に加熱された合金材を用いると累積減面率を高くすることができ、効率のよい加工ができる。
【００３１】
前記中間焼鈍は冷間加工による合金材の異方性を少なくし、材料全体を均質な軟質体として提供するものであるが、前記範囲外で焼鈍すると不均質になったり、表面が過剰に酸化されたりすることで、次の冷間加工において、少ない減面率で破断や割れを生じてしまう。
【００３２】
前記第２の熱間加工後に、以降の工程において表面欠陥や加工破断の原因となる表面に形成された高温で生成された酸化層（以下、高温酸化層と略す）を表面処理によって除去することが望ましい。通常、酸を用いた酸洗処理で行うが、機械研磨法などを用いてもよい。
しかしながら、前記高温酸化層を完全に除去し、合金地肌を曝すことは、次工程の冷間加工において摩擦係数を増大させて、表面の割れや破断を生じやすくし、冷間加工性を損なうことになるために、最表面に形成された高温酸化層を主として除去するものである。
なお、表面清浄工程は、健全な表面性状を作り出すために、中間焼鈍を含む冷間加工による減面処理中にも適時行うことができる。この場合も、前記高温酸化層の時と同様に表面に形成された脆弱な表面酸化層のみを除去することが望ましい。
【００３３】
次に、先に述べた高温下での十分な加工と併せて本発明に係る形状回復性を具現化するのに必要な仕上げ冷間加工と熱処理からなる形状記憶処理について述べる。
【００３４】
前記工程を経てきた本発明合金材において、仕上げ冷間加工における累積減面率は少なくとも２５％以上、望ましくは３０％以上の累積減面率で加工するのがよい。累積減面率が小さい加工では、次の熱処理後にすべり変形に対して充分な抵抗力を得ることができず、外力に対して容易にすべり変形を生じて形状回復性を示さなくなる。
１パスあたりの減面率は７％〜１５％の範囲で加工することが望ましい。７％未満では、中心部まで十分な加工が施されず異方性の大きな材料となり、加工時の破断の原因となったり、良好な形状が得られなかったりする。１パスあたりの減面率が１５％を超えると割れが発生し易くなる。
【００３５】
前記仕上げ冷間加工後に行う熱処理は、５５０℃〜８２０℃の温度で、且つ、５分〜１２０分間の熱処理を行うことで、先の仕上げ冷間加工と相まって完全に回復する形状回復伸び量が２％以上である形状記憶効果および超弾性をもたらすが、熱処理温度が低い場合や熱処理時間が短い場合には、完全な形状記憶効果及び超弾性を示さない。更に、過剰に施された場合には、再結晶が起こり、容易にすべり変形して形状記憶効果および超弾性を示さなくなる。
【００３６】
なお、溶解鋳造工程は、従来のＮｉＴｉ系形状記憶合金と同様に、真空または不活性雰囲気下の黒鉛坩堝中で溶解鋳造することが望ましい。ＴｉとＮｉの反応によって生じる反応熱によってＺｒ元素が溶解できるようにＮｉ原料、Ｔｉ原料、Ｚｒ原料の順に黒鉛坩堝中に配置する。
【００３７】
【実施例】
以下に本発明を実施例により詳細に説明する。
（実施例１）
Ｎｉを４９．５ｍｏｌ％、Ｚｒを１０．０ｍｏｌ％、Ｈｆを０．０７ｍｏｌ％含み、残部Ｔｉと不可避不純物とからなる合金を秤量後、真空溶解鋳造炉内に設置された黒鉛坩堝内で溶解した後、水冷鋳型に鋳込んでφ３８×Ｌ２００ｍｍの鋳塊を作製した。この鋳塊を、表１の本発明製造法のＡ〜Ｃに示した製造方法で加工し、累積減面率３５％の仕上げ冷間加工を施して厚さ０．６ｍｍの板材又は線径１ｍｍの線材に仕上げた。なお、この工程中に表面清浄を目的とした化学腐食と機械研磨工程を適時行った。
次に、この線材および板材に、表２の形状記憶処理を行い、表２の本発明例１のＮｏ．１〜Ｎｏ．４の合金材を作製した。そしてＡｆ温度、形状記憶効果および超弾性を以下の方法で測定した。
Ａｆ温度は、ＤＳＣを用いて、温度範囲−５０℃〜２５０℃、昇温速度及び降温速度を1０℃／分として測定した。
形状記憶効果及び超弾性の測定は、ＪＩＳＨ７１０３−２００２に基づいて行い、３％の引張伸びを与えた後に抜重したときの形状回復伸び量を測定した。
なお、形状記憶効果は２５℃の測定温度で行い、抜重後、試料をＡｆ温度以上に加熱して形状回復伸び量を測定した。超弾性の測定については、Ａｆ温度＋２０℃の恒温槽中で行った。
完全に回復した場合を「○」で記し、完全に回復しなかった場合には、回復しなかった伸び量を示した。
【００３８】
（実施例２）
Ｎｉを５０．２５ｍｏｌ％、Ｚｒを１４．０ｍｏｌ％、Ｈｆを０．３ｍｏｌ％含み、残部Ｔｉと不可避不純物とからなる合金を用いた以外は、前記実施例１と同様に本発明製造法のＡ〜Ｃの製造方法で作製して、表２の本発明例２のＮｏ．５〜Ｎｏ．８の合金材を得て、各特性を測定した。
【００３９】
（実施例３）
前記実施例１と同じ合金を用いて、第１の熱間加工の加工条件を変えた本発明製造法のＤ、Ｅで作製して、表２の本発明例３のＮｏ．９、Ｎｏ．１０の合金材を得て、各特性を測定した。
【００４０】
（実施例４）
表２の比較例のＮｏ．１１〜Ｎｏ．１７は、前記実施例１と同じ合金を用いて、表１の比較製造法ｆ〜ｌにより厚さ０．６ｍｍの板材又は線径１ｍｍの線材を作製し、表２に示す条件で形状記憶処理を行い、前記実施例１と同じく各特性を測定した。
実施例１、２，３、４の測定結果を表２に記した。
【００４１】
【表１】

【００４２】
【表２】

【００４３】
表２から明らかなように、本発明例１、２、３のＮｏ．１〜Ｎｏ．１０は、１００℃以上のＡｆ温度を示すと共に、２％以上の完全に回復する形状回復伸び量を有する形状記憶効果および超弾性の両形状回復性を示すことが判る。
図１（ａ）に、表２の本発明例１のＮｏ．２の形状記憶効果を示す測定結果を示し、図１（ｂ）に、超弾性の測定結果を示す。
【００４４】
仕上げ冷間加工の累積減面率が１５％と小さい以外は、表２の本発明例1のＮｏ．２と同じく作製した表２の比較例のＮｏ．１１では、１００℃以上のＡｆ温度は得られたが、完全な形状回復性を得ることはできなかった。
【００４５】
第２の熱間加工の加工温度が、８５０℃と高い表２の比較例のＮｏ．１２は、この第２の熱間加工で芯割れが発生してしまい、以降の工程に進めなかった。
【００４６】
第１の熱間加工の加工温度が、８５０℃と低い表２の比較例のＮｏ．１３では、鋳塊熱間押出し力が過重となり金型を壊してしまった。
【００４７】
表２の比較例のＮｏ．１４では、中間の焼鈍温度が低かったために、焼鈍後の冷間加工中に合金材が破断してしまい合金材が作製できなかった
【００４８】
中間加工において、１パスごとの減面率が５％と小さい表２の比較例のＮｏ．１５では、表面のみが硬化してしまい、加工途中で合金材が蛇行したり、破断したりして合金材を作製できなかった。
【００４９】
熱間加工後に、表面の高温酸化層を除去しなかった表２の比較例のＮｏ．１６では、冷間加工中に破断を頻発してしまい合金材が作製できなかった。
【００５０】
第１の熱間加工に、熱間圧延を用いた表２の比較例のＮｏ．１７では、熱間圧延中に側端に割れが発生し、それが圧延毎に成長してしまい、健全な熱間加工材を得られなかった。
【００５１】
【発明の効果】
以上に説明したように、本発明に係る形状記憶合金材は、１００℃以上のＡｆ温度を示し、且つ２％以上の工業上利用可能なレベルの形状回復伸び量を有し、しかも前記形状記憶合金材は、製造条件を規定することにより容易に製造することができる。従って、工業上顕著な効果を奏する。
【図面の簡単な説明】
【図１】（ａ）本発明例１のＮｏ．２の形状記憶効果を示す応力−ひずみ曲線
（ｂ）本発明例１のＮｏ．２の超弾性を示す応力−ひずみ曲線[0001]
BACKGROUND OF THE INVENTION
The present invention provides a shape recovery elongation that completely recovers in the shape memory effect or superelasticity that uses external force as the driving force, and the martensite reverse transformation end temperature (hereinafter referred to as Af temperature) is 100 ° C. or higher. However, it relates to a shape memory alloy material of 2% or more and a manufacturing method thereof.
[0002]
[Prior art]
The Ni—Ti-based shape memory alloy exhibits a shape memory effect and superelasticity due to thermoelastic martensitic transformation. The thermoelastic martensitic transformation includes martensite transformation start temperature (hereinafter abbreviated as Ms temperature), martensite transformation end temperature (hereinafter abbreviated as Mf temperature), martensite reverse transformation start temperature (hereinafter abbreviated as As temperature), and The four transformation temperatures of the Af temperature dominate the use of the shape memory alloy, but there is no Ni—Ti shape memory alloy having a good shape recovery property and having a transformation temperature of 100 ° C. or higher. This is a barrier to increasing demand for memory alloys.
[0003]
In order to achieve a transformation temperature of 100 ° C. or higher, a method by adding a third element has been proposed. (1) Addition of Pd element, (2) Addition of Hf element and Zr element (for example,

Patent Documents

1 and 2; 3 and 4) are known.
[0004]
In Patent Document 1 of (2) above, the influence of the alloy composition on the transformation temperature is shown. This is the transformation temperature of the ingot, and the transformation of the material obtained by shape memory heat treatment of the cold work material actually used. Different from temperature. Furthermore, there is no disclosure of manufacturing methods that can be performed by those skilled in the art.
[0005]
On the other hand, in Patent Document 2, a change in transformation temperature (for example, FIG. 1, FIG. 2, FIG. 5 and FIG. 5), a change in hardness (for example, FIG. 3), and a change in tensile strength (for example, FIG. 6) is stated. Moreover, the transformation temperature behavior (for example, FIG. 7) of the Ni—Ti—Zr alloy when Zr element is contained up to 8 mol% is shown. Furthermore, a method for producing a Ni—Ti—Hf alloy by hot working with a single area reduction of 15% or less is disclosed.
[0006]
In Patent Document 3, B is added to facilitate cold working, and the Ni-Ti-Zr alloy not added with B element is cracked during hot forging press, but contains B element. In the Ni—Ti—Zr—B alloy, a wire having a wire diameter of 1 mm is obtained without cracking in a hot forging press.
[0007]
In Patent Document 4, the hot workability is improved by coating the Ni—Ti—Zr alloy with mild steel, but in the case of no coating, cracking occurs in the hot upset forging method. There is.
[0008]
[Patent Document 1]
Japanese Patent Laid-Open No. 3-72046 [Patent Document 2]
JP-A-5-43969 [Patent Document 3]
Japanese Patent Laid-Open No. 10-8168 [Patent Document 4]
JP 10-36952 A [Non-Patent Document 1]
Edited by Funakubo Yasuyasu, “Shape Memory Alloy”, First Edition, Sangyo Tosho Co., Ltd., June 7, 1984, p. 158
[0009]
[Problems to be solved by the invention]
In the prior arts shown in Patent Documents 1 to 4, it is shown that the Af temperature is 100 ° C. or higher in a range overlapping with the component composition of the alloy according to the present invention.
However, when shape memory alloys are used industrially, it is important whether the shape memory effect using temperature as a drive source and the superelastic shape recovery using external force as a drive source can be obtained at an industrial use level. However, Patent Documents 1 to 4 have a problem that the shape recoverability is not known at all. In particular, Patent Document 2 in which an alloy is produced under specific manufacturing conditions is expected to disclose shape recovery, but only the relationship between stress and strain is shown, and shape recovery is not clear. .
[0010]
By the way, it is well known that both the shape memory effect and the superelastic shape recovery are highly dependent on both the component composition and the manufacturing method, particularly on the manufacturing method. In order to obtain a particularly good shape recovery property, it is necessary to have a high critical stress against slip deformation so that the alloy is difficult to slip.
[0011]
Therefore, the present invention embodies the shape recoverability in an Ni-Ti-Zr alloy or Ni-Ti-Zf-Hf alloy having an Af temperature of 100 ° C. or more that lacks the shape recoverability, An object of the present invention is to provide a shape memory alloy material useful in use and a method for producing the same.
Specifically, it has a shape memory effect or superelasticity showing a fully recovering shape recovery elongation amount of 2% or more at an industrial utilization level, and a high shape recovery property showing an Af temperature of 100 ° C. or higher. A shape memory alloy material having a high transformation temperature and a method for producing the same.
[0012]
[Means for solving the problems]
The invention described in claim 1 is a shape memory alloy comprising 49.5 to 50.25 mol% Ni and 8 to 20 mol% Zr, and the balance Ti and inevitable impurities, and is perfect in shape memory effect or superelasticity. A shape memory alloy material having a high shape recovery property and a high transformation temperature with a shape recovery elongation of 2% or more and a martensite reverse transformation end temperature of 100 ° C. or more.
[0013]
The invention according to claim 2 is a shape memory alloy comprising 49.5 to 50.25 mol% Ni, 8 to 20 mol% Zr, less than 0.1 mol% Hf, and the balance Ti and inevitable impurities. A shape memory alloy material having a high shape recovery property and a high transformation temperature having a shape recovery elongation of 2% or more and a martensite reverse transformation finish temperature of 100 ° C. or more.
[0014]
The invention according to claim 3 is a manufacturing method of a shape memory alloy material in which hot working, cold working (including intermediate annealing), and shape memory heat treatment are performed on a Ni—Ti based alloy. And the second hot working is carried out at a temperature of 880 ° C. to 1030 ° C. at least once and the cumulative area reduction is 40% or more by the extrusion method, and then the second hot working. 3. The method for producing a shape memory alloy material having a high shape recovery property and a high transformation temperature according to claim 1, wherein the processing is performed at a temperature of 600 ° C. to 830 ° C.
[0015]
According to a fourth aspect of the present invention, in the manufacturing method of a shape memory alloy material in which hot working, cold working (including intermediate annealing), and shape memory heat treatment are performed on a Ni-Ti alloy, the hot working is the first. And the first hot working is carried out at a temperature of 880 ° C. to 1030 ° C. at least once by an extrusion method at a cumulative area reduction of 40% or more, and then cooled to room temperature. 3. A shape memory alloy having high shape recoverability and high transformation temperature according to claim 1 or 2, wherein the second hot working is performed by heating to 600 ° C to 830 ° C after being held in the vicinity. It is a manufacturing method of material.
[0016]
The invention according to claim 5 is a method of manufacturing a shape memory alloy material in which a Ni—Ti alloy is subjected to hot working, cold working (including intermediate annealing), and shape memory treatment. Includes intermediate annealing and surface-reducing treatment by processing at room temperature, and the intermediate annealing has a relationship between temperature and time of (a) 680 ° C. × 10 minutes, (b) 680 ° C. × 180 minutes, ( c) A parallelogram of the temperature-time plane formed by connecting four conditions of 820 ° C. × 30 minutes and (d) 820 ° C. × 2 in the order of (a), (b), (c), (d) It is carried out under a combination of conditions corresponding to the temperature and holding time within the range (on the line or inside), and after the intermediate annealing, the single processing rate is 7 to 15%. After the intermediate annealing, the single processing rate is 7 to The surface reduction treatment is performed at 15%, and the cumulative processing rate during intermediate annealing is 20 to 40%. Or method for producing a shape memory alloy material having a high shape recovery and high transformation temperature according to claim 2, wherein.
[0017]
The invention according to claim 6 is a manufacturing method of a shape memory alloy material in which a Ni—Ti alloy is subjected to hot working, cold working (including intermediate annealing), and shape memory processing. The finish cold working is performed at a cumulative area reduction rate of 25% or more in a range of 7% to 15% in area reduction per pass, and then at 550 ° C to 820 ° C. The method for producing a shape memory alloy material having a high shape recovery property and a high transformation temperature according to claim 1, wherein the heat treatment is performed at a temperature for 5 minutes to 120 minutes.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the alloy material and the manufacturing method thereof according to the present invention will be described below.
First, in the present invention, the basis for defining the shape recovery elongation amount to be completely recovered to 2% or more is that when the shape memory alloy is deformed, the deformation exhibiting a linear reversible behavior in the shape memory effect is 1% in terms of the elongation amount. The deformation that exhibits a linear reversible behavior in the case of superelasticity is 1 to 1.5% in elongation (see, for example, Non-Patent Document 1). That is, when the shape memory effect and superelasticity, which are non-linear reversible behaviors, are used industrially, a shape recoverability greater than the amount of elongation showing the linear reversible behavior is required. Therefore, the shape recovery elongation that completely recovers as an industrial utilization level is set to 2% or more.
[0019]
Next, in order to have an Af temperature of 100 ° C. or higher, obtain a good shape recoverability, and more easily manufacture, Ni was 49.5 to 50.25 mol%, and Zr was 8 to 20 mol%.
If Ni is less than 49.5 mol%, it hardly contributes to the increase in Af temperature, and the workability is extremely lowered by increasing the ratio of Ti to Ni. The content exceeding 50.25 mol% is limited because the Af temperature cannot be increased to 100 ° C. or higher despite the Zr content.
[0020]
If Zr is less than 8 mol%, an Af temperature of 100 ° C. or higher cannot be stably obtained, and if it exceeds 20 mol%, melt castability and workability deteriorate, and a sound alloy material cannot be obtained.
[0021]
By the way, Zr and Hf belong to the same group 2 in terms of atomic periodicity, and it is difficult to completely separate Hf from the Zr raw material, and the general Zr raw material contains 1-2 mass% of Hf. Yes. Therefore, in the present invention, the shape memory alloy is produced by selecting a Zr raw material having a small amount of Hf. However, if the Hf content is 0.1 mol% or more, it becomes difficult to control the Af temperature. .
[0022]
In the production method according to the present invention, the Ni—Ti—Zr alloy or the Ni—Ti—Zr—Hf alloy having the above composition has the shape recovery elongation of 2% or more, and the alloy ingot is used. It has been found that it is necessary to sufficiently process at a high temperature.
[0023]
This high-temperature processing (hot processing) is performed in order to eliminate the ingot structure that adversely affects cold processing and shape recoverability, but the alloy ingot having the component composition has strong anisotropy against stress. Therefore, an extrusion method in which the cross section is constrained in all directions is suitable as the processing method, particularly in the first hot processing.
[0024]
In the present invention, the reason why the first hot working is heated and held at 880 ° C. to 1030 ° C. and then processed at least once by the extrusion method at a cumulative area reduction of 40% or more will be described below.
If it is less than 880 ° C., the force required for processing becomes excessive, which may cause damage to the processing apparatus, and the ingot structure cannot be sufficiently broken, so that a material exhibiting good workability and characteristics cannot be obtained. If it exceeds 1030 ° C., the processing becomes easy but the influence of surface oxidation becomes extremely large, and it becomes easy to become the starting point of material breakage during the second hot processing or cold processing to be performed next, and in some cases This is because a melting phenomenon occurs, cracks occur during the hot working, and the processing becomes impossible.
[0025]
The reason why the cumulative area reduction rate is limited to 40% or more is that if the accumulated area reduction ratio is less than 40%, the ingot structure cannot be changed sufficiently to form a work structure, and cracks and shapes may not be formed in the following process. This is because the control is insufficient and a material having good characteristics cannot be produced. In addition, since it becomes difficult to process when the cumulative surface reduction rate exceeds 80%, the cumulative processing rate is preferably between 50% and 80%.
[0026]
In addition, in a forging method in which the constraining surfaces are limited to the upper and lower surfaces and a processing method such as a rolling method in which the processing speed is fast under a loose constraint, cracking occurs at the initial stage of processing and the processing becomes impossible. In addition, in the method of thinning the ingot by repeatedly heating and hot working at a small area reduction of about 5 to 15%, which is the hot working method of the ingot described in Patent Document 2, the ingot Although it is possible to reduce the thickness, it is difficult to make the ingot structure into a uniform processed structure, and good shape recoverability cannot be obtained. Furthermore, a repeated high-temperature heat treatment results in the formation of a thick brittle oxide layer on the alloy surface, leading to work cracks in subsequent steps.
[0027]
The alloy material that has been subjected to the first hot working is then reduced in diameter or thinned by the second hot working, but the second hot working is continued from the first hot working. Alternatively, the alloy material may be once cooled and then reheated. Within the scope of the present invention, the workability is not significantly changed, and an alloy material having good characteristics is obtained. Can do. If the first and second hot working are continuously performed, productivity can be improved and thermal energy can be reduced.
[0028]
The reason for limiting the second hot working to 600 to 830 ° C. is that at low temperatures outside the above range, deformation resistance becomes large, cracking and a predetermined area reduction rate cannot be obtained, and productivity is lowered. I will invite you. If it is high, the temperature inside the alloy material rises during processing, and a core crack that breaks from the center portion occurs.
The area reduction rate in one process in the second hot working is preferably 7% or more, and preferably 10 to 30%.
[0029]
Next, the alloy material subjected to the first and second hot working is subjected to surface reduction treatment by cold working including intermediate annealing, thereby having processing to a predetermined dimension and good shape recoverability. The tissue is homogenized.
In the intermediate annealing, the relationship between the annealing temperature and time is (a) 680 ° C. × 10 minutes, (b) 680 ° C. × 180 minutes, (c) 820 ° C. × 30 minutes, (d) 820 ° C. × 2 minutes. It is better to anneal under conditions within the specified range.
[0030]
The reason why the area reduction rate per pass in the cold working is 7% to 15% is that if it is less than 7%, the material is not sufficiently processed to the center and becomes a highly anisotropic material. In addition, a good shape cannot be obtained. Cracks occur when the area reduction per pass exceeds 15%. Therefore, the area reduction rate in the range of 7% to 15% is good. The reason for limiting the cumulative area reduction ratio during the intermediate annealing to 20% to 45% is that if it is less than 20%, the number of annealing increases unnecessarily and the productivity is not increased, contributing to an increase in cost. If it exceeds, the processing becomes difficult, and the area reduction rate per pass becomes less than 7%, and cracking occurs.
If an alloy material heated to a temperature higher by 10 to 30 ° C. than the Af temperature of the ingot is used for the cold working, the cumulative area reduction rate can be increased and efficient machining can be performed.
[0031]
The intermediate annealing reduces the anisotropy of the alloy material due to cold working and provides the entire material as a homogeneous soft body. However, annealing outside the above range may cause inhomogeneity or excessive oxidation of the surface. As a result, in the next cold working, breakage and cracking occur with a small area reduction.
[0032]
After the second hot working, an oxide layer (hereinafter, abbreviated as a high temperature oxide layer) formed at a high temperature formed on the surface that causes surface defects or work breaks in the subsequent steps is removed by surface treatment. Is desirable. Usually, it is performed by pickling using an acid, but a mechanical polishing method or the like may be used.
However, completely removing the high-temperature oxide layer and exposing the alloy background increases the coefficient of friction in the cold working of the next process, easily causes surface cracks and breaks, and impairs cold workability. Therefore, the high-temperature oxide layer formed on the outermost surface is mainly removed.
In addition, in order to produce a healthy surface property, the surface cleaning process can be performed in a timely manner during the surface reduction process by cold working including intermediate annealing. Also in this case, it is desirable to remove only the fragile surface oxide layer formed on the surface as in the case of the high temperature oxide layer.
[0033]
Next, a shape memory process composed of a finish cold working and a heat treatment necessary for realizing the shape recoverability according to the present invention in combination with the sufficient working at a high temperature described above will be described.
[0034]
In the alloy material of the present invention that has undergone the above-described process, it is preferable that the cumulative area reduction in finish cold working is at least 25% or more, preferably 30% or more. In processing with a small cumulative area reduction rate, sufficient resistance to slip deformation cannot be obtained after the next heat treatment, and slip deformation easily occurs with respect to external force, resulting in no shape recovery.
It is desirable that the area reduction rate per pass is in the range of 7% to 15%. If it is less than 7%, sufficient processing is not performed up to the center portion, resulting in a material having large anisotropy, which may cause breakage during processing or a good shape may not be obtained. If the area reduction rate per pass exceeds 15%, cracking is likely to occur.
[0035]
The heat treatment performed after the finish cold working has a shape recovery elongation amount that is completely recovered by performing the heat treatment at a temperature of 550 ° C. to 820 ° C. and for 5 minutes to 120 minutes. A shape memory effect and superelasticity of 2% or more are brought about, but when the heat treatment temperature is low or the heat treatment time is short, the complete shape memory effect and superelasticity are not exhibited. Furthermore, if it is applied excessively, recrystallization will occur and it will slip easily and will not show shape memory effect and superelasticity.
[0036]
In the melt casting process, it is desirable to melt and cast in a graphite crucible in a vacuum or in an inert atmosphere as in the case of conventional NiTi shape memory alloys. The Ni raw material, the Ti raw material, and the Zr raw material are arranged in this order in the graphite crucible so that the Zr element can be dissolved by the reaction heat generated by the reaction between Ti and Ni.
[0037]
【Example】
Hereinafter, the present invention will be described in detail with reference to examples.
Example 1
An alloy consisting of 49.5 mol% Ni, 10.0 mol% Zr and 0.07 mol% Hf and the balance Ti and inevitable impurities was weighed and then melted in a graphite crucible installed in a vacuum melting casting furnace. Thereafter, it was cast into a water-cooled mold to produce an ingot of φ38 × L200 mm. This ingot is processed by the manufacturing methods shown in A to C of the manufacturing method of the present invention in Table 1, and finish cold working with a cumulative area reduction rate of 35% is performed to give a plate material having a thickness of 0.6 mm or a wire diameter of 1 mm. Finished with a wire rod. During this process, chemical corrosion and mechanical polishing processes for the purpose of surface cleaning were performed in a timely manner.
Next, the shape memory processing of Table 2 was performed on the wire and the plate material, and No. 1 of Invention Example 1 of Table 2 was obtained. 1-No. 4 alloy material was produced. The Af temperature, shape memory effect and superelasticity were measured by the following methods.
The Af temperature was measured using DSC, with a temperature range of −50 ° C. to 250 ° C., a temperature increase rate and a temperature decrease rate of 10 ° C./min.
The shape memory effect and superelasticity were measured in accordance with JIS H7103-2002, and the amount of shape recovery elongation was measured when it was pulled after giving 3% tensile elongation.
The shape memory effect was performed at a measurement temperature of 25 ° C., and after drawing, the sample was heated to the Af temperature or higher to measure the shape recovery elongation. The superelasticity was measured in a constant temperature bath at Af temperature + 20 ° C.
The case of complete recovery was marked with “◯”, and when the recovery was not complete, the amount of elongation that did not recover was shown.
[0038]
(Example 2)
A of the production method of the present invention is the same as in Example 1 except that an alloy containing Ni of 50.25 mol%, Zr of 14.0 mol%, Hf of 0.3 mol% and the balance of Ti and inevitable impurities is used. To C, and No. 1 of Invention Example 2 in Table 2 was prepared. 5-No. The alloy material of 8 was obtained and each characteristic was measured.
[0039]
(Example 3)
Using the same alloy as in Example 1 above, it was prepared by D and E of the manufacturing method of the present invention in which the processing conditions of the first hot working were changed. 9, no. Ten alloy materials were obtained and each characteristic was measured.
[0040]
(Example 4)
No. of the comparative example of Table 2. 11-No. No. 17 uses the same alloy as in Example 1 above to produce a 0.6 mm-thick plate or a wire with a diameter of 1 mm by the comparative production methods f to 1 in Table 1, and shape memory treatment under the conditions shown in Table 2 Each characteristic was measured in the same manner as in Example 1.
The measurement results of Examples 1, 2, 3, and 4 are shown in Table 2.
[0041]
[Table 1]

[0042]
[Table 2]

[0043]
As is apparent from Table 2, Nos. 1-No. No. 10 shows an Af temperature of 100 ° C. or higher and a shape memory effect having a shape recovery elongation of 2% or more and a shape recovery effect of superelasticity and both shape recovery properties.
In FIG. 1A, No. 1 of Invention Example 1 in Table 2 is shown. The measurement result which shows the shape memory effect of 2 is shown, and the measurement result of superelasticity is shown in FIG.1 (b).
[0044]
No. 1 of Invention Example 1 in Table 2 except that the cumulative area reduction in finish cold working is as small as 15%. No. 2 of the comparative example of Table 2 produced in the same manner as in FIG. In No. 11, an Af temperature of 100 ° C. or higher was obtained, but complete shape recoverability could not be obtained.
[0045]
The processing temperature of the second hot working is as high as 850 ° C. In No. 12, a core crack occurred in the second hot working, and it was not possible to proceed to the subsequent steps.
[0046]
The processing temperature of the first hot working is as low as 850 ° C. In No. 13, the ingot hot extrusion force became excessive and the mold was broken.
[0047]
No. of the comparative example of Table 2. In No. 14, since the intermediate annealing temperature was low, the alloy material broke during cold working after annealing, and the alloy material could not be produced.
In the intermediate machining, the No. of the comparative example in Table 2 is as small as 5% in the area reduction per pass. In No. 15, only the surface was cured, and the alloy material meandered or broke during processing, and the alloy material could not be produced.
[0049]
After the hot working, the high temperature oxide layer on the surface was not removed. In No. 16, breakage occurred frequently during cold working, and an alloy material could not be produced.
[0050]
No. of the comparative example of Table 2 which used hot rolling for the 1st hot processing. In No. 17, cracks occurred at the side edges during hot rolling, which grew every time rolling, and a healthy hot-worked material could not be obtained.
[0051]
【The invention's effect】
As described above, the shape memory alloy material according to the present invention has an Af temperature of 100 ° C. or higher, has a shape recovery elongation amount of 2% or more of an industrially usable level, and also has the shape memory. The alloy material can be easily manufactured by defining manufacturing conditions. Therefore, there is an industrially significant effect.
[Brief description of the drawings]
1 (a) No. 1 of Invention Example 1; Stress-strain curve (b) showing the shape memory effect of No. 2 of Invention Example 1. Stress-strain curve showing superelasticity of 2

Claims

Ｎｉを４９．５〜５０．２５ｍｏｌ％、Ｚｒを８〜２０ｍｏｌ％含み、残部Ｔｉと不可避不純物とからなる形状記憶合金であって、形状記憶効果または超弾性における完全に回復する形状回復伸び量が２％以上、且つマルテンサイト逆変態終了温度が１００℃以上の高形状回復性および高変態温度を有する形状記憶合金材。A shape memory alloy containing 49.5 to 50.25 mol% of Ni and 8 to 20 mol% of Zr, the balance being Ti and inevitable impurities, and having a shape memory elongation or a shape recovery elongation that completely recovers in superelasticity A shape memory alloy material having a high shape recovery property and a high transformation temperature of 2% or more and a martensite reverse transformation end temperature of 100 ° C. or more.

Ｎｉを４９．５〜５０．２５ｍｏｌ％、Ｚｒを８〜２０ｍｏｌ％、Ｈｆを０．１ｍｏｌ％未満含み、残部Ｔｉと不可避不純物とからなる形状記憶合金であって、形状記憶効果または超弾性における完全に回復する形状回復伸び量が２％以上、且つマルテンサイト逆変態終了温度が１００℃以上の高形状回復性および高変態温度を有する形状記憶合金材。A shape memory alloy containing 49.5 to 50.25 mol% Ni, 8 to 20 mol% Zr, less than 0.1 mol% Hf, and the balance Ti and inevitable impurities, and has complete shape memory effect or superelasticity A shape memory alloy material having a high shape recovery property and a high transformation temperature having a shape recovery elongation of 2% or more and a martensite reverse transformation end temperature of 100 ° C. or more.

Ｎｉ−Ｔｉ系合金に、熱間加工、冷間加工（中間焼鈍を含む）、形状記憶処理を施す形状記憶合金材の製造方法において、前記熱間加工を第１と第２に分けて行い、前記第１の熱間加工を押出し法により８８０℃〜１０３０℃の温度で、少なくとも1回以上、累積減面率が４０％以上で行い、引き続き第２の熱間加工を６００℃〜８３０℃の温度で行うことを特徴とする請求項１または請求項２記載の高形状回復性および高変態温度を有する形状記憶合金材の製造方法。In the manufacturing method of a shape memory alloy material in which hot working, cold working (including intermediate annealing), and shape memory processing are performed on a Ni-Ti alloy, the hot working is performed in first and second steps, The first hot working is performed by extrusion at a temperature of 880 ° C. to 1030 ° C. at least once and the cumulative area reduction is 40% or more, and then the second hot working is performed at 600 ° C. to 830 ° C. The method for producing a shape memory alloy material having a high shape recovery property and a high transformation temperature according to claim 1 or 2, wherein the method is performed at a temperature.

Ｎｉ−Ｔｉ系合金に、熱間加工、冷間加工（中間焼鈍を含む）、形状記憶処理を施す形状記憶合金材の製造方法において、前記熱間加工を第１と第２に分けて行い、前記第１の熱間加工を押出し法により８８０℃〜１０３０℃の温度で、少なくとも1回以上、累積減面率が４０％以上で行い、その後、冷却して常温近辺に保持した後、６００℃〜８３０℃に加熱して第２の熱間加工を行うことを特徴とする請求項１または請求項２記載の高形状回復性および高変態温度を有する形状記憶合金材の製造方法。In the manufacturing method of a shape memory alloy material in which hot working, cold working (including intermediate annealing), and shape memory processing are performed on a Ni-Ti alloy, the hot working is performed in first and second steps, The first hot working is performed at a temperature of 880 ° C. to 1030 ° C. at least once by an extrusion method at a cumulative area reduction of 40% or more, and then cooled and kept at around room temperature, then 600 ° C. The method for producing a shape memory alloy material having high shape recoverability and high transformation temperature according to claim 1 or 2, wherein the second hot working is performed by heating to ~ 830 ° C.

Ｎｉ−Ｔｉ系合金に、熱間加工、冷間加工（中間焼鈍を含む）、形状記憶処理を施す形状記憶合金材の製造方法において、前記冷間加工（中間焼鈍を含む）が、中間焼鈍と常温状態での加工による減面処理からなり、前記中間焼鈍は、温度と時間の関係が（ａ）６８０℃×１０分、（ｂ）６８０℃×１８０分、（ｃ）８２０℃×３０分、（ｄ）８２０℃×２分の４条件を、（ａ）、（ｂ）、（ｃ）、（ｄ）の順に結んでできる温度−時間平面の平行四辺形の範囲内（線上または内側）の温度・保持時間に相当する組み合わせの条件で行われ、前記中間焼鈍後、１回の加工率が７〜１５％、且つ、中間焼鈍間の累積加工率を２０〜４０％で減面処理することを特徴とする請求項１または請求項２記載の高形状回復性および高変態温度を有する形状記憶合金材の製造方法。In the manufacturing method of a shape memory alloy material in which hot working, cold working (including intermediate annealing), and shape memory treatment are performed on a Ni-Ti alloy, the cold working (including intermediate annealing) is performed by intermediate annealing. The intermediate annealing includes a surface reduction process by processing at room temperature, and the intermediate annealing has a relationship between temperature and time: (a) 680 ° C. × 10 minutes, (b) 680 ° C. × 180 minutes, (c) 820 ° C. × 30 minutes, (D) Within the range of the parallelogram (on the line or inside) of the temperature-time plane formed by connecting 820 ° C. × 4/2 conditions in the order of (a), (b), (c), (d) Surface reduction treatment is performed under a combination of conditions corresponding to temperature and holding time, and after the intermediate annealing, the processing rate per process is 7 to 15%, and the cumulative processing rate during the intermediate annealing is 20 to 40%. The shape having high shape recovery property and high transformation temperature according to claim 1 or 2, Method of manufacturing a 憶合 alloy material.

Ｎｉ−Ｔｉ系合金に、熱間加工、冷間加工（中間焼鈍を含む）、形状記憶処理を施す形状記憶合金材の製造方法において、前記形状記憶処理は仕上げ冷間加工とそれに続く熱処理からなり、前記仕上げ冷間加工を累積減面率で２５％以上、１パスあたりの減面率で７％〜１５％の範囲で行い、次いで、５５０℃〜８２０℃の温度で、５分〜１２０分間熱処理することを特徴とする請求項１または請求項２記載の高形状回復性および高変態温度を有する形状記憶合金材の製造方法。In a manufacturing method of a shape memory alloy material in which a Ni-Ti alloy is subjected to hot working, cold working (including intermediate annealing), and shape memory processing, the shape memory processing includes finish cold working and subsequent heat treatment. The finish cold working is performed at a cumulative area reduction rate of 25% or more in a range of 7% to 15% area reduction per pass, and then at a temperature of 550 ° C. to 820 ° C. for 5 minutes to 120 minutes. The method for producing a shape memory alloy material having high shape recovery property and high transformation temperature according to claim 1 or 2, wherein heat treatment is performed.