JP2004035974A

JP2004035974A - PRECIPITATION STRENGTHENING TYPE Co-Ni-BASED HEAT RESISTANT ALLOY AND MANUFACTURING METHOD THEREFOR

Info

Publication number: JP2004035974A
Application number: JP2002197142A
Authority: JP
Inventors: Masahiko Chiba; 千葉　晶彦; Shiro Takeda; 武田　士郎; Tomohiko Ayada; 綾田　倫彦; Shigemi Sato; 佐藤　繁美; Shigenori Ueda; 植田　茂紀; Toshiharu Noda; 野田　俊治
Original assignee: Daido Steel Co Ltd; NHK Spring Co Ltd; Tohoku Nippatsu Co Ltd
Current assignee: Daido Steel Co Ltd; NHK Spring Co Ltd; Tohoku Nippatsu Co Ltd
Priority date: 2002-07-05
Filing date: 2002-07-05
Publication date: 2004-02-05
Anticipated expiration: 2022-07-05
Also published as: DE60302108T8; DE60302108T2; EP1378579B1; US20040033158A1; DE60302108D1; EP1378579A1; JP4264926B2; ES2250793T3

Abstract

<P>PROBLEM TO BE SOLVED: To provide a precipitation strengthening type Co-Ni-based heat resistant alloy, to be more specific, the precipitation strengthening type Co-Ni-based heat resistant alloy which has Co<SB>3</SB>Mo or Co<SB>7</SB>Mo<SB>6</SB>precipitated in an interface between a fine twin structure and a parent phase, and is suitable for a spring, a bolt or the like used in a site exposed to a high temperature such as an engine exhaust system and a perimeter of a gas turbine, and to provide a manufacturing method therefor. <P>SOLUTION: This alloy comprises, by wt.%, 0.05% or less C, 0.5% or less Si, 1.0% or less Mn, 25-45% Ni, 13-22% Cr, 10-18% of Mo+1/2W, 0.1-5.0% Nb, 0.1-5.0% Fe, further one or more elements of 0.007-0.10% REM, 0.001-0.010% B, 0.0007-0.010% Mg, and 0.001-0.20% Zr, and 0.1-3.0% Ti as needed, and the balance Co with unavoidable impurities, and has a structure in which Co<SB>3</SB>Mo or Co<SB>7</SB>Mo<SB>6</SB>is precipitated in the interface between the fine twin structure and the parent phase. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
本発明は、析出強化型Ｃｏ−Ｎｉ基耐熱合金およびその製造方法、詳細にはエンジン排気系、ガスタービン周辺などの高温に曝される部位で使用されるばね、ボルトなどに適している微細双晶組織と母相の界面にＣｏ_３ＭｏまたはＣｏ_７Ｍｏ_６が析出した析出強化型Ｃｏ−Ｎｉ基耐熱合金およびその製造方法に関する。
【０００２】
【従来の技術】
従来、エンジン排気系、ガスタービン周辺などの高温にさらされる部位で使用される耐熱部品は、インコネルＸ−７５０（Ｎｉ：７３．０％、Ｃｒ：１５．０％、Ａｌ：０．８％、Ｔｉ：２．５％、Ｆｅ：６．８％、Ｍｎ：０．７０％、Ｓｉ：０．２５％、Ｃ：０．０４、Ｎｂ＋Ｔａ：０．９％）、インコネル７１８（Ｎｉ：５３．０％、Ｃｒ：１８．６％、Ｍｏ：３．１％、Ａｌ：０．４％、Ｔｉ：０．９％、Ｆｅ：１８．５％、Ｍｎ：０．２０％、Ｓｉ：０．１８％、Ｃ：０．０４、Ｎｂ＋Ｔａ：５．０％）などのＮｉ基超耐熱合金を用いて製造されていた。
【０００３】
これらのＮｉ基超耐熱合金は、γ′（　Ｎｉ_３（Ａｌ，Ｔｉ，Ｎｂ）　およびγ′′（Ｎｉ_３Ｎｂ）　を析出させることによって強化するものである。しかし、６００℃以上の高温で長時間使用すると、過時効によりγ′およびγ′′が粗大化して強度が低下するという欠点があった。また、ばね、ボルトなどの常に応力がかかっている部品では応力緩和が大きく、本来の部品に要求される性能が保持できなくなってしまうという問題があった。
【０００４】
そこで、本出願人達は、Ｃ：０．０５％以下、Ｓｉ：０．５％以下、Ｍｎ：１．０％以下、Ｎｉ：２５〜４５％、Ｃｒ：１３〜１８未満％、ＭｏとＷの１種または２種でＭｏ＋１／２　Ｗ：７〜２０％、Ｔｉ：０．１〜３．０％、Ｎｂ：０．１〜５．０％およびＦｅ：０．１〜５．０％を含有し、必要に応じてＲＥＭ：０．００７〜０．１０％、Ｂ：０．００１〜０．０１０％、Ｍｇ：０．０００７〜０．０１０％およびＺｒ：０．００１〜０．２０％のうちの１種または２種以上を含有し、残部がＣｏおよび不可避的不純物からなるＣｏ−Ｎｉ基耐熱合金ならびにこの合金を１０００〜１２００℃で固溶化熱処理を施した後または上記温度での熱間加工を施した後、加工率４０％以上の冷間または温間加工を施し、その後５００〜８００℃で０．１〜５０時間の時効熱処理を施すＣｏ−Ｎｉ基耐熱合金の製造方法を開発し、特開２００２−９７５３７号として特許出願した。
【０００５】
このＣｏ−Ｎｉ基耐熱合金は、σ相を析出させるＣｒ含有量を必要最低限にし、拡張転位の積層欠陥に偏析して転位運動を妨げ、高い加工硬化能を有するＭｏ，Ｆｅ，Ｎｂなどの溶質元素を多くしたもので、従来から用いられていたＮｉ基超耐熱合金より室温における強度が高いとともに、高温で長時間使用しても強度の低下が小さいものである。
【０００６】
【発明が解決しようとする課題】
本発明は、上記Ｎｉ基超耐熱合金より高強度であるとともに、高温で長時間使用しても強度の低下が小さい耐熱合金およびその製造方法を提供することを課題とするものである。
【０００７】
【課題を解決するための手段】
上記課題を解決するため、本発明者らは、Ｎｉ基超耐熱合金より高強度であるとともに、高温で長時間使用しても強度の低下が小さい耐熱合金である上記Ｃｏ−Ｎｉ基耐熱合金について成分組成、時効熱処理条件などを更に調査、研究をしていたところ、このＣｏ−Ｎｉ基耐熱合金を応力負荷状態で時効熱処理をするかまたは高温で時効熱処理をすることにより数ミクロンサイズの平均粒径を有する微細双晶組織が生成され、またこの微細双晶組織と母相の界面に数ミクロンから数十ナノメーターサイズのＣｏ_３ＭｏまたはＣｏ_７Ｍｏ_６を析出すること（本発明の実施例２２の組織写真である図１および図２参照）、このような組織にすると高強度であるとともに、高温で長時間使用しても強度の低下が小さい耐熱合金になること、また固溶化熱処理後に加工率４０％以上の冷間または温間加工をし、その後時効熱処理を施すと、冷間または温間加工によってマトリックス中に高密度の転位が導入され、その後施す時効熱処理により析出する析出物によって転位が固着されて高温強度が改善され、また転位の積層欠陥面にＭｏなどの溶質元素が偏析して転位が固着される効果により室温および高温強度の改善効果が発揮されることの知見を得た。
【０００８】
また、数ミクロンサイズの平均粒径を有する微細双晶組織を生成させ、この微細双晶組織と母相の界面に数ミクロンから数十ナノメーターサイズの微細析出物、すなわちＣｏ_３ＭｏまたはＣｏ_７Ｍｏ_６を析出させるには、固溶化熱処理後に応力負荷状態で６００〜８００℃に適当時間加熱する時効熱処理を施すか、固溶化熱処理後に加工率４０％以上の冷間または温間加工を施し、続いて応力負荷状態で６００〜８００℃に適当時間加熱する時効熱処理を施すか、または固溶化熱処理後に加工率４０％以上の冷間または温間加工を施し、続いて８００℃を超え９５０℃以下の範囲で適当時間加熱する時効熱処理を施せばよいことなどの知見を得た。
本発明は、これらの知見に基づいて発明をされたものである。
【０００９】
すなわち、本発明の析出強化型Ｃｏ−Ｎｉ基耐熱合金においては、Ｃ：０．０５％以下、Ｓｉ：０．５％以下、Ｍｎ：１．０％以下、Ｎｉ：２５〜４５％、Ｃｒ：１３〜２２％、ＭｏまたはＭｏとＷでＭｏ＋１／２　Ｗ：１０〜１８％、Ｎｂ：０．１〜５．０％およびＦｅ：０．１〜５．０％を含有し、更にＲＥＭ：０．００７〜０．１０％、Ｂ：０．００１〜０．０１０％、Ｍｇ：０．０００７〜０．０１０％およびＺｒ：０．００１〜０．２０％のうちの１種または２種以上を含有し、必要に応じてＴｉ：０．１〜３．０％を含有し、残部がＣｏおよび不可避的不純物からなり、微細双晶組織と母相の界面にＣｏ_３ＭｏまたはＣｏ_７Ｍｏ_６が析出した組織のものとすることである。
【００１０】
本発明の微細双晶組織を形成させ、同時にこの微細双晶組織と母相の界面にＣｏ_３ＭｏまたはＣｏ_７Ｍｏ_６が析出した析出強化型Ｃｏ−Ｎｉ基耐熱合金の製造方法においては、Ｃ：０．０５％以下、Ｓｉ：０．５％以下、Ｍｎ：１．０％以下、Ｎｉ：２５〜４５％、Ｃｒ：１３〜２２％、ＭｏまたはＭｏとＷでＭｏ＋１／２　Ｗ：１０〜１８％、Ｎｂ：０．１〜５．０％およびＦｅ：０．１〜５．０％を含有し、更にＲＥＭ：０．００７〜０．１０％、Ｂ：０．００１〜０．０１０％、Ｍｇ：０．０００７〜０．０１０％およびＺｒ：０．００１〜０．２０％のうちの１種または２種以上を含有し、必要に応じてＴｉ：０．１〜３．０％を含有し、残部がＣｏおよび不可避的不純物からなる合金を１０００〜１２００℃などで加熱する固溶化熱処理をし、その後に応力負荷状態で６００〜８００℃に０．５〜１６時間加熱する時効熱処理を施すことである。
【００１１】
さらに、本発明の微細双晶組織を形成させ、同時にこの微細双晶組織と母相の界面にＣｏ_３ＭｏまたはＣｏ_７Ｍｏ_６が析出した析出強化型Ｃｏ−Ｎｉ基耐熱合金の製造方法においては、Ｃ：０．０５％以下、Ｓｉ：０．５％以下、Ｍｎ：１．０％以下、Ｎｉ：２５〜４５％、Ｃｒ：１３〜２２％、ＭｏまたはＭｏとＷでＭｏ＋１／２　Ｗ：１０〜１８％、Ｎｂ：０．１〜５．０％およびＦｅ：０．１〜５．０％を含有し、更にＲＥＭ：０．００７〜０．１０％、Ｂ：０．００１〜０．０１０％、Ｍｇ：０．０００７〜０．０１０％およびＺｒ：０．００１〜０．２０％のうちの１種または２種以上を含有し、必要に応じてＴｉ：０．１〜３．０％を含有し、残部がＣｏおよび不可避的不純物からなる合金を１０００〜１２００℃などで加熱する固溶化熱処理をし、その後に加工率４０％以上の冷間または温間加工を施し、続いて応力負荷状態で６００〜８００℃に０．５〜１６時間加熱する時効熱処理を施すことである。
【００１２】
また、本発明の微細双晶組織を形成させ、同時にこの微細双晶組織と母相の界面にＣｏ_３ＭｏまたはＣｏ_７Ｍｏ_６が析出した析出強化型Ｃｏ−Ｎｉ基耐熱合金の製造方法においては、Ｃ：０．０５％以下、Ｓｉ：０．５％以下、Ｍｎ：１．０％以下、Ｎｉ：２５〜４５％、Ｃｒ：１３〜２２％、ＭｏまたはＭｏとＷでＭｏ＋１／２　Ｗ：１０〜１８％、Ｎｂ：０．１〜５．０％およびＦｅ：０．１〜５．０％を含有し、更にＲＥＭ：０．００７〜０．１０％、Ｂ：０．００１〜０．０１０％、Ｍｇ：０．０００７〜０．０１０％およびＺｒ：０．００１〜０．２０％のうちの１種または２種以上を含有し、必要に応じてＴｉ：０．１〜３．０％を含有し、残部がＣｏおよび不可避的不純物からなる合金を１０００〜１２００℃などで加熱する固溶化熱処理をし、その後に加工率４０％以上の冷間または温間加工を施し、続いて無負荷状態で８００℃を超え９５０℃以下の範囲に０．５〜１６時間加熱する時効熱処理を施すことである。
【００１３】
【作用】
本発明の析出強化型Ｃｏ−Ｎｉ基耐熱合金は、微細双晶組織と母相の界面に微細析出物が析出し、この微細析出物が▲１▼７００℃程度の高温においても成長して粗大化しないし、▲２▼さらに転位と引力相互作用をするため７００℃以上の高温においても転位を有効に固着する効果を発揮し、▲３▼また数ミクロンサイズの平均粒径を有する微細双晶組織の粒界に析出するため、７００℃以上の高温において粒界の移動などの際に障害物とし粒界すべりを抑制し、かつ結晶粒の粗大成長を阻止するため、これらにより耐クリープ特性などの高温強度に優れたものとなる。
【００１４】
さらに、本発明の析出強化型Ｃｏ−Ｎｉ基耐熱合金の製造方法において、１０００〜１２００℃等で加熱する固溶化熱処理後に応力負荷状態で６００〜８００℃に０．５〜１６時間加熱する時効熱処理を施すか、上記固溶化熱処理後に加工率４０％以上の冷間または温間加工を施し、続いて応力負荷状態で６００〜８００℃に０．５〜１６時間加熱する時効熱処理を施すか、または上記固溶化熱処理後に加工率４０％以上の冷間または温間加工を施し、続いて８００℃を超え９５０℃以下の範囲で０．５〜１６時間加熱する時効熱処理を施しているので、微細双晶組織を形成させ、同時にこの微細双晶組織と母相の界面にＣｏ_３Ｍｏおよび／またはＣｏ_７Ｍｏ_６を析出させることができる。
【００１５】
【発明の実施の形態】
次に、本発明の析出強化型Ｃｏ−Ｎｉ基耐熱合金およびその製造方法において成分組成を上記のように限定した理由を説明する。
Ｃ：０．０５％以下
Ｃは、ＮｂやＴｉと結合して炭化物を形成し、固溶化熱処理時の結晶粒の粗大化を防止するとともに、粒界の強化に寄与するので、それらのために含有する元素である。それらの効果を得るためには、好ましくは０．００５％以上含有させる必要があるが、０．０５％、好ましくは０．０３％より多く含有させると靱性および耐食性を低下させるともに、転位を固着させる元素、例えばＭｏと炭化物を形成して転位の固着効果を阻害することになるので、その含有量を０．０５％以下とする。好ましい範囲は０．００５〜０．０３％である。
【００１６】
Ｓｉ：０．５％以下
Ｓｉは、脱酸剤として有効であるので、そのために含有させる元素であるが、０．５％、好ましくは０．３％を超えて含有させると靱性を低下させるので、その含有量を０．５％以下とする。好ましい含有量は０．３％以下である。
【００１７】
Ｍｎ：１．０％以下
Ｍｎは、脱酸剤として有効であり、また積層欠陥エネルギーを低下させて加工硬化能を向上させるので、それらのために含有させる元素であるが、１．０％、好ましくは０．７％を超えて含有させると、耐食性を低下させるので、その含有量を１．０％以下とする。好ましい含有量は０．７％以下である。
【００１８】
Ｎｉ：２５〜４５％
Ｎｉは、マトリックスであるオーステナイトを安定化させる元素であり、合金の耐熱性および耐食性を向上させるので、それらのために含有させる元素である。それらの効果を得るには２５％、好ましくは２７％以上含有させる必要があるが、４５％を超えると加工硬化能を低下させるので、その含有範囲を２５〜４５％とする。好ましい含有範囲は２７〜４５％である。
【００１９】
Ｃｒ：１３〜２２％
Ｃｒは、耐熱性および耐食性を改善させるので、それらのために含有させる元素である。それらの効果を得るには１３％、好ましくは１６％以上含有させる必要があるが、２２％以上、好ましくは２１％を超えるとσ相を析出しやすくするので、その含有範囲を１３〜２２％とする。好ましい含有範囲は１６〜２１％である。
【００２０】
Ｍｏ＋１／２Ｗ：１０〜１８％
ＭｏおよびＷは、マトリックスに固溶してこれを強化し、加工硬化能を向上させるので、そのために含有させる元素である。その効果を得るためには１０％、好ましくは１１％以上で、ＭｏとＷの両方を含有する場合には好ましくはＭｏを８．０％以上含有させる必要があるが、１８％を超えるとσ相が析出するので、その含有範囲を１０〜１８％とする。好ましい含有範囲は１１〜１８％である。
【００２１】
Ｎｂ：０．１〜５．０％
Ｎｂは、Ｃと結合して炭化物を形成して固溶化熱処理時の結晶粒の粗大化を防止するとともに、粒界の強化に寄与し、またマトリックスに固溶してこれを強化させ、加工硬化能を向上させるので、それらのために含有させる元素である。それらの効果を得るには０．１％、好ましくは０．８％以上含有させる必要があるが、５．０％、好ましくは３．０％を超えるとδ相（Ｎｉ_３Ｎｂ）が析出して加工性および靱性を低下させるので、その含有範囲を０．１〜５．０％とする。好ましい含有範囲は０．８〜３．０％である。
【００２２】
Ｆｅ：０．１〜５．０％
Ｆｅは、マトリックスに固溶してこれを強化するので、そのために含有させる元素である。その効果を得るためには０．１％、好ましくは０．５％以上含有させる必要があるが、５．０％、好ましくは４．８％を超えると耐酸化性を低下させるので、その含有範囲を０．１〜５．０％とする。好ましい範囲は０．５〜４．８％である。
なお、ＭｏとＮｂとＦｅを複合して用いれば、ＭｏとＮｂ、ＭｏとＦｅの複合で用いるよりマトリックスの固溶強化と加工硬化を著しく増大させ、室温および高温において得られる引張最大強度を著しく高め、また高温における引張強度の極大が現れる温度を高温に移行させる効果も大きい。
【００２３】
Ｔｉ：０．１〜３．０％
Ｔｉは、強度を向上させるので、そのために含有させる元素である。その効果を得るためには０．１％、好ましくは０．５％以上含有させる必要があるが、３．０％、好ましくは２．５％を超えるとη相（Ｎｉ_３Ｔｉ）が析出して加工性および靱性を低下させるので、その含有範囲を０．１〜３．０％とする。好ましい含有範囲は０．５〜２．５％である。
【００２４】
ＲＥＭ：０．００７〜０．１０％
Ｙ，Ｃｅ、ミッシュメタルなどの希土類元素の１種または２種以上であるＲＥＭは、熱間加工性および耐酸化性を向上させるので、それらのために含有させる元素である。それらの効果を得るには、０．００７％、好ましくは０．０１％以上含有させる必要があるが、０．１０％、好ましくは０．０４％を超えると逆に熱間加工性および耐酸化性を低下させるので、その含有範囲を０．００７〜０．１０％とする。好ましい含有範囲は０．０１〜０．０４％である。
【００２５】
Ｂ：０．００１〜０．０１０％、Ｍｇ：０．０００７〜０．０１０％、Ｚｒ：０．００１〜０．２０％
Ｂ，ＭｇおよびＺｒは、熱間加工性を向上させるとともに、粒界を強化するので、それらのために含有させる元素である。それらの効果を得るには、Ｂを０．００１％、好ましくは０．００２％以上、Ｍｇを０．０００７％、好ましくは０．００１％以上、Ｚｒを０．００１％、好ましくは０．０１％以上を含有させる必要があるが、Ｂを０．０１０％、好ましくは０．００６％、Ｍｇを０．０１０％、好ましくは０．００４％、Ｚｒを０．２０％、好ましくは０．０５％を超えて含有させると逆に熱間加工性および耐酸化性を低下させるので、その含有範囲を上記のとおりとする。好ましい範囲はＢが０．００２〜０．００６％、Ｍｇが０．００１〜０．００４％、Ｚｒが０．０１〜０．０５％である。
【００２６】
Ｃｏ：残部
Ｃｏは、最密六方格子であるが、Ｎｉを含有させることにより面心立方格子、すなわちオーステナイトとなり、高い加工硬化能を示す。
【００２７】
本発明の析出強化型Ｃｏ−Ｎｉ基耐熱合金は、上記成分組成からなり、その組織が微細双晶組織と母相の界面にＣｏ_３ＭｏまたはＣｏ_７Ｍｏ_６が析出したものである。
【００２８】
次に、本発明の析出強化型Ｃｏ−Ｎｉ基耐熱合金の製造方法について説明する。本発明の析出強化型Ｃｏ−Ｎｉ基耐熱合金の製造方法は、上記成分組成の析出強化型Ｃｏ−Ｎｉ基耐熱合金に数ミクロンサイズの平均粒径を有する微細双晶組織を生成させ、またこの微細双晶組織と母相の界面に数ミクロンから数十ナノメーターサイズのＣｏ_３ＭｏまたはＣｏ_７Ｍｏ_６を析出させることにより高強度であるとともに、高温で長時間使用しても強度の低下が小さくなるようにするためのものである。
【００２９】
そのため、本発明のＣｏ−Ｎｉ基耐熱合金材の製造方法は、上記Ｃｏ−Ｎｉ基耐熱合金を１０００〜１２００℃などで加熱する固溶化熱処理を施し、その後に応力負荷状態で６００〜８００℃に０．５〜１６時間加熱する時効熱処理を施すか、固溶化熱処理を施し、その後に加工率４０％以上の冷間または温間加工を施し、続いて応力負荷状態で６００〜８００℃に０．５〜１６時間加熱する時効熱処理を施すか、または固溶化熱処理を施し、加工率４０％以上の冷間または温間加工を施し、続いて無負荷状態で８００℃を超え９５０℃以下の範囲で０．５〜１６時間加熱する時効熱処理を施すことである。
【００３０】
本発明の析出強化型Ｃｏ−Ｎｉ基耐熱合金の製造方法において行う固溶化熱処理は、組織を均質にするとともに、硬度を低くして加工を容易にするためのもので、１０００〜１２００℃に加熱することによって行うのが好ましい。１０００℃より低いと十分均質にならないばかりでなく、硬度も低くならず、加工が難しいからであり、さらに転位の固着効果に寄与するＭｏなどの化合物の析出、それに起因する時効硬化性を低減させるおそれがあるからである。また１２００℃を超えると結晶粒が粗大化して靱性および強度が低下するからである。
【００３１】
本発明の析出強化型Ｃｏ−Ｎｉ基耐熱合金の製造方法において、析出強化型Ｃｏ−Ｎｉ基耐熱合金を応力負荷状態で６００〜８００℃に０．５〜１６時間加熱する時効熱処理をするのは、数ミクロンサイズの平均粒径を有する微細双晶組織が生成させるとともに、この微細双晶組織と母相の界面に数ミクロンから数十ナノメーターサイズのＣｏ_３ＭｏまたはＣｏ_７Ｍｏ_６を析出させるためである。この時効熱処理における負荷応力は、１００〜４００ＭＰａ程度が適当である。１００ＭＰａより低いと微細双晶組織および微細双晶組織と母相の界面に微細なＣｏ_３ＭｏまたはＣｏ_７Ｍｏ_６が十分析出しないからであり、また４００ＭＰａより大きくても効果が飽和し、また時効熱処理する合金が変形するからである。
【００３２】
また、６００〜８００℃で０．５〜１６時間加熱する時効熱処理をするのは、６００℃より低く、また０．５時間より短いと微細双晶組織および微細双晶組織と母相の界面に微細なＣｏ_３ＭｏまたはＣｏ_７Ｍｏ_６が十分析出しないからであり、また８００℃を超え、また１６時間を超えると効果が飽和し、むしろ、析出物が粗大化し、強度が低下してしまうからであり、更に加工率４０％以上の冷間または温間加工を施した後にこの時効熱処理を行う場合には、転位が回復して硬度および強度が低下し、クリープ伸びが大きくなるからである。
【００３３】
本発明の析出強化型Ｃｏ−Ｎｉ基耐熱合金の他の製造方法において、析出強化型Ｃｏ−Ｎｉ基耐熱合金を応力負荷状態で時効熱処理をする前に加工率４０％以上の冷間または温間加工を施すのは、高密度の転位を導入するためであり、４０％より低いと高密度の転位を導入することができないからである。高密度の転位を導入した後時効熱処理をすると、Ｍｏ、Ｆｅなどの溶質原子を拡張した転位の半転位間に形成された積層欠陥に偏析させて転位運動を妨げることで応力緩和、すなわち転位の回復を抑制することになる。その結果、微細双晶組織および微細双晶組織と母相の界面に微細なＣｏ_３ＭｏまたはＣｏ_７Ｍｏ_６が析出することによる効果と相まって高強度であるとともに、高温で長時間使用しても強度の低下が小さい析出強化型Ｃｏ−Ｎｉ基耐熱合金となる。
【００３４】
本発明の析出強化型Ｃｏ−Ｎｉ基耐熱合金の他の製造方法において、固溶化熱処理を施した後加工率４０％以上の冷間または温間加工を施した後、高温の８００℃を超え９５０℃以下の範囲で０．５〜１６時間加熱する時効熱処理を施すのは、数ミクロンサイズの平均粒径を有する微細双晶組織が生成させるとともに、この微細双晶組織と母相の界面に数ミクロンから数十ナノメーターサイズのＣｏ_３ＭｏまたはＣｏ_７Ｍｏ_６を析出させるためである。本発明のこの方法と異なる析出強化型Ｃｏ−Ｎｉ基耐熱合金の他の製造方法においては、応力負荷状態で時効熱処理をしているが、本発明のこの製造方法においては、応力負荷状態で時効熱処理をする代わりに高温の８００℃を超え９５０℃以下の範囲で加熱する時効熱処理をするのである。この製造方法において、８００℃を超えて、また０．５時間以上で時効熱処理するのは、８００℃以下、また０．５時間より短いと微細双晶組織および微細双晶組織と母相の界面に微細なＣｏ_３ＭｏまたはＣｏ_７Ｍｏ_６が十分析出しないからである。また、９５０℃以下、１６時間以下で時効熱処理するのは、９５０℃より高温度、１６時間より長い時間時効熱処理をしても効果が飽和し、析出物の固溶または粗大化が生じ、強度が低下するからである。
【００３５】
本発明の析出強化型Ｃｏ−Ｎｉ基耐熱合金の製造方法の一例は、真空高周波誘導炉などを用いて通常の方法で溶製し、通常の鋳造方法で鋳造してインゴットを製造する。その後熱間加工をし、１０００〜１２００℃で固溶化熱処理を施した後、１００〜４００ＭＰａの応力負荷状態で６００〜８００℃に０．５〜１６時間加熱する時効熱処理を施すか、上記固溶化熱処理を施した後加工率４０％以上の冷間または温間加工を施し、続いて１００〜４００ＭＰａの応力負荷状態で６００〜８００℃に０．５〜１６時間加熱する時効熱処理を施すか、または上記固溶化熱処理を施した後加工率４０％以上の冷間または温間加工を施し、続いて８００℃を超え９５０℃以下の範囲で０．５〜１６時間加熱する時効熱処理を施すことである。
【００３６】
また、本発明の析出強化型Ｃｏ−Ｎｉ基耐熱合金の用途は、エンジンの排気マニホールドなどの排気系部品、ガスタービン周辺機器、炉部材、耐熱ばね、耐熱ボルトなどのインコネルＸ７５０またはインコネルＸ７１８を用いていた用途およびこれら以上の高温度で用いる用途である。特に、高温において常に応力がかかっているばね、ボルトなどの部品に好適である。
【００３７】
【実施例】
以下、本発明を実施例によって説明する。
実施例１
下記表１に示す成分組成の本発明例および比較例の合金を真空高周波誘導炉を用いて通常の方法で溶製し、通常の鋳造方法で鋳造して５０ｋｇのインゴットを得た。これらのインゴットを熱間鍛造によりφ２０ｍｍの丸棒にした。その後１１００℃で固溶化熱処理をし、引張応力２００ＭＰａ下で７２０℃×８時間の時効処理を行った。これらの素材から平行部φ８ｍｍの引張試験片を切り出し、室温で引張試験をして引張強度を測定した。また平行部φ６ｍｍで評点間距離３０ｍｍのクリープ試験片を切り出し、７００℃で３３０ＭＰａの応力を負荷して１０００時間後の伸びを測定するクリープ試験を行った。これらの結果を表２に示す。また、表２にはミクロ組織で観察された析出物の同定結果を示す。
【００３８】
【表１】

【００３９】
【表２】

【００４０】
実施例２
上記実施例１（表１）の本発明例　Ｎｏ．５および　Ｎｏ．６の合金のφ２０ｍｍの丸棒を１１００℃で固溶化熱処理をし、本発明例として引張応力２５０ＭＰａ下で６２０℃×１５時間加熱する時効熱処理、引張応力２００ＭＰａ下で７２０℃×８時間加熱する時効熱処理、引張応力１２０ＭＰａ下で７７０℃×４時間加熱する時効処理をした。比較例として引張応力８０ＭＰａ下で８５０℃×４時間加熱する時効熱処理または引張応力２５０ＭＰａ下で５５０℃×１５時間加熱する時効熱処理を行った。これらの素材から上記実施例１と同様のクリープ試験片を切り出し、実施例１と同様な条件でクリープ試験をしてクリープを測定した。その結果を下記表３に示す。
【００４１】
【表３】

【００４２】
実施例３
上記実施例１（表１）の本発明例　Ｎｏ．５およびＮｏ．　６の合金のφ２０ｍｍの丸棒を１１００℃で固溶化熱処理をし、本発明例として加工率４５％、６０％、７５％の冷間加工を施した後、表４に示す負荷応力、加熱温度および加熱時間で時効熱処理を行った。比較例として加工率４５％の冷間加工を施した後、無負荷で７７０℃×４時間加熱する時効熱処理または加工率６０％の冷間加工を施した後、無負荷で７２０℃×８時間加熱する時効熱処理を行った。これらの素材から上記実施例１と同様のクリープ試験片を切り出し、実施例１と同様な条件でクリープ試験をしてクリープを測定した。その結果を下記表４に示す。
【００４３】
【表４】

【００４４】
実施例４
上記実施例１（表１）の本発明例　Ｎｏ．５およびＮｏ．　６の合金のφ２０ｍｍの丸棒を１１００℃で固溶化熱処理をし、本発明例として加工率６０％、７５％の冷間加工を施した後、無負荷で８５０℃×４時間または９２０℃×２時間加熱する時効処理を行った。また比較例として加工率３５％の冷間加工を施した後、無負荷で９２０℃×２時間加熱する時効処理または加工率７５％の冷間加工を施した後、無負荷で９９０℃×２時間加熱する時効処理を行った。これらの素材から上記実施例１と同様のクリープ試験片を切り出し、実施例１と同様な条件でクリープ試験をしてクリープを測定した。その結果を下記表５に示す。
【００４５】
【表５】

【００４６】
これらの結果によると、本発明例　Ｎｏ．１〜７（表２）は、試験片の組織をＳＥＭ（走査型電子顕微鏡）観察すると微細双晶組織が形成されており、さらにその微細双晶組織と母相の界面に微細なＣｏ_７Ｍｏ_６またはＣｏ_３Ｍｏが析出しており、室温引張強さが１１２１〜１３０３ＭＰａであり、クリープ伸びが２．０〜２．７％であった。　これらに対して、Ｍｏ＋１／２　Ｗが本発明より少ない比較例Ｎｏ．１〜３およびＭｏ＋１／２　Ｗが本発明より少なく、またＮｂとＦｅを含有しない比較例　Ｎｏ．４は、Ｃｏ_７Ｍｏ_６またはＣｏ_３Ｍｏが析出しておらず、室温引張強さが８８１〜９７６ＭＰａで、本発明例の８７％以下であり、クリープ試験ではいずれの試験片も破断した。
【００４７】
本発明例　Ｎｏ．８〜１３（表３）は、試験片の組織をＳＥＭ観察すると微細双晶組織が形成されており、さらにその微細双晶組織と母相の界面に微細なＣｏ_３ＭｏまたはＣｏ_７Ｍｏ_６が析出しており、クリープ試験のクリープ伸びが２．０〜２．９％であった。
これらに対して、時効熱処理温度が本発明より高い比較例　Ｎｏ．５および本発明より低い比較例　Ｎｏ．６は、Ｃｏ_３ＭｏまたはＣｏ_７Ｍｏ_６が析出しておらず、比較例　Ｎｏ．５はクリープ試験で試験片が破断し、また比較例　Ｎｏ．６はクリープ試験のクリープ伸びが４．６％であり、クリープ強度の向上がみられなかった。
【００４８】
本発明例　Ｎｏ．１４〜２２（表４）は、試験片の組織をＳＥＭ観察すると微細双晶組織が形成されており、さらにその微細双晶組織と母相の界面に微細なＣｏ_３ＭｏまたはＣｏ_７Ｍｏ_６が析出している。図１および図２は、本発明例　Ｎｏ．２２の組織写真である。この組織写真から正三角形状に見える微細双晶組織と母相の界面に塊状に見えるＣｏ_３ＭｏまたはＣｏ_７Ｍｏ_６が析出した組織であることが分かる。本発明例　Ｎｏ．１４〜２２のクリープ試験のクリープ伸びが０．９〜１．９％であった。これらは、クリープ試験のクリープ伸びが時効熱処理をする前に４０％以上の冷間または温間加工をしない本発明例　Ｎｏ．１〜１３より小さくなっていた。
これらに対して、時効熱処理時に負荷を与えなかった比較例　Ｎｏ．７および　Ｎｏ．８は、Ｃｏ_３ＭｏまたはＣｏ_７Ｍｏ_６が析出しておらず、クリープ試験のクリープ伸びが４．８％と４．６％であり、クリープ強度の向上がみられなかった。
【００４９】
本発明例　Ｎｏ．２３〜２８（表５）は、試験片の組織をＳＥＭ観察すると微細双晶組織が形成されており、さらにその微細双晶組織と母相の界面に微細なＣｏ_３ＭｏまたはＣｏ_７Ｍｏ_６が析出しており、クリープ試験のクリープ伸びが１．３〜１．９％で、実施例３（表４）の本発明例　Ｎｏ．１４〜２２と同程度であった。これらに対して、冷間加工率が本発明より低い比較例　Ｎｏ．９は、Ｃｏ_３ＭｏまたはＣｏ_７Ｍｏ_６が析出しておらず、またクリープ試験のクリープ伸びが４．６％でクリープ強度の向上がみられなかった。また時効熱処理温度が本発明より高い比較例　Ｎｏ．１０は、クリープ試験中に試験片が破断した。この試験片の組織を観察したところ、再結晶組織となっており、９９０℃の時効処理では微細双晶組織と析出物が消失したものと考えられる。
【００５０】
【発明の効果】
本発明の析出強化型Ｃｏ−Ｎｉ基耐熱合金は、従来から用いられていたＮｉ基超耐熱合金より室温における強度が高いとともに、高温で長時間使用しても強度の低下が小さいという優れた効果を奏する。
また、本発明の製造方法は、上記Ｎｉ基超耐熱合金より室温における強度が高いとともに、高温で長時間使用しても強度の低下が小さい析出強化型Ｃｏ−Ｎｉ基耐熱合金材を製造することができるという優れた効果を奏する。
【図面の簡単な説明】
【図１】本発明の実施例　Ｎｏ．２２の組織を５０００倍に拡大した図面代用走査型電子顕微鏡写真である。
【図２】図１のものの組織を２００００倍に拡大した図面代用走査型電子顕微鏡写真である。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a precipitation-hardened Co—Ni-based heat-resistant alloy and a method for producing the same, and more particularly, a fine twin suitable for springs and bolts used in parts exposed to high temperatures such as an engine exhaust system and a gas turbine. Co at the interface between the crystal structure and the matrix ₃ Mo or Co ₇ Mo ₆ The present invention relates to a precipitation-strengthened Co—Ni-based heat-resistant alloy in which is deposited and a method for producing the same.
[0002]
[Prior art]
Conventionally, heat-resistant components used in parts exposed to high temperatures, such as engine exhaust systems and gas turbines, include Inconel X-750 (Ni: 73.0%, Cr: 15.0%, Al: 0.8%, Ti: 2.5%, Fe: 6.8%, Mn: 0.70%, Si: 0.25%, C: 0.04, Nb + Ta: 0.9%), Inconel 718 (Ni: 53.0) %, Cr: 18.6%, Mo: 3.1%, Al: 0.4%, Ti: 0.9%, Fe: 18.5%, Mn: 0.20%, Si: 0.18% , C: 0.04, Nb + Ta: 5.0%) and the like.
[0003]
These Ni-base super heat-resistant alloys are made of γ ′ (Ni ₃ (Al, Ti, Nb) and γ ″ (Ni ₃ Nb) is precipitated by precipitation. However, when used at a high temperature of 600 ° C. or higher for a long time, γ ′ and γ ″ become coarse due to overaging, and the strength is reduced. In addition, there is a problem in that a component that is always under stress, such as a spring or a bolt, has a large stress relaxation, and cannot maintain the performance required for the original component.
[0004]
Therefore, the present applicants have proposed that C: 0.05% or less, Si: 0.5% or less, Mn: 1.0% or less, Ni: 25 to 45%, Cr: 13 to less than 18%, and Mo and W One or two types contain Mo + 1/2 W: 7 to 20%, Ti: 0.1 to 3.0%, Nb: 0.1 to 5.0%, and Fe: 0.1 to 5.0%. If necessary, REM: 0.007 to 0.10%, B: 0.001 to 0.010%, Mg: 0.0007 to 0.010%, and Zr: 0.001 to 0.20% A Co-Ni-based heat-resistant alloy containing one or more of them, with the balance being Co and inevitable impurities, and after subjecting this alloy to a solution heat treatment at 1000 to 1200 ° C or a hot work at the above temperature. After working, cold or warm working at a working ratio of 40% or more is performed, and then at 500 to 800 ° C. A method for producing a Co—Ni-based heat-resistant alloy subjected to aging heat treatment for 0.1 to 50 hours was developed, and a patent application was filed as JP-A-2002-97537.
[0005]
This Co—Ni-based heat-resistant alloy minimizes the Cr content for precipitating the σ phase, segregates into extended dislocation stacking faults, hinders dislocation motion, and has a high work hardening ability such as Mo, Fe, and Nb. It has a large amount of solute elements, has higher strength at room temperature than a conventionally used Ni-based super heat-resistant alloy, and has a small decrease in strength even when used at a high temperature for a long time.
[0006]
[Problems to be solved by the invention]
An object of the present invention is to provide a heat-resistant alloy having higher strength than the above-mentioned Ni-based super-heat-resistant alloy and having a small decrease in strength even when used at a high temperature for a long time, and a method for producing the same.
[0007]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present inventors have developed a Co-Ni-based heat-resistant alloy which has higher strength than a Ni-based super-heat-resistant alloy, and has a small decrease in strength even when used at a high temperature for a long time. The composition and aging heat treatment conditions were further investigated and researched. The aging heat treatment of this Co-Ni-based heat-resistant alloy under stress load condition or the aging heat treatment at high temperature resulted in the average grain size of several microns. A fine twin structure having a diameter is generated, and Co at a size of several microns to tens of nanometers is formed at the interface between the fine twin structure and the parent phase. ₃ Mo or Co ₇ Mo ₆ (See FIGS. 1 and 2 which are photographs of the structure of Example 22 of the present invention). Such a structure has a high strength, and has a small decrease in strength even when used for a long time at a high temperature. It becomes an alloy, and after the solution heat treatment, cold or warm working at a working ratio of 40% or more, and then aging heat treatment, high density dislocations are introduced into the matrix by cold or warm working, Dislocations are fixed by precipitates deposited by the subsequent aging heat treatment to improve the high-temperature strength by improving the high-temperature strength, and the effect of solute elements such as Mo segregating on the dislocation stacking surface to fix the dislocations to improve the room temperature and high-temperature strength. The knowledge that the effect is exhibited was obtained.
[0008]
Further, a fine twin structure having an average particle size of several microns is generated, and fine precipitates of several microns to several tens of nanometers, that is, Co, are formed at the interface between the fine twin structure and the matrix. ₃ Mo or Co ₇ Mo ₆ In order to precipitate, an aging heat treatment of heating at 600 to 800 ° C. for an appropriate time under a stress load state after a solution heat treatment or a cold or warm work at a working ratio of 40% or more after a solution heat treatment is performed. An aging heat treatment of heating to 600 to 800 ° C. for an appropriate time under a stress load state, or a cold or warm working at a working ratio of 40% or more after a solution heat treatment, followed by a range of more than 800 ° C. and 950 ° C. or less It was found that aging heat treatment for heating for an appropriate time may be performed.
The present invention has been made based on these findings.
[0009]
That is, in the precipitation-strengthened Co—Ni-based heat-resistant alloy of the present invention, C: 0.05% or less, Si: 0.5% or less, Mn: 1.0% or less, Ni: 25 to 45%, Cr: 13 to 22%, Mo or Mo plus W, Mo + 1/2 W: 10 to 18%, Nb: 0.1 to 5.0%, and Fe: 0.1 to 5.0%, and REM: 0 0.007 to 0.10%, B: 0.001 to 0.010%, Mg: 0.0007 to 0.010%, and Zr: 0.001 to 0.20%. Containing, if necessary, 0.1 to 3.0% of Ti, with the balance being Co and unavoidable impurities, and Co at the interface between the fine twin structure and the parent phase. ₃ Mo or Co ₇ Mo ₆ Is a structure in which is precipitated.
[0010]
The fine twin structure of the present invention is formed, and at the same time, Co is formed at the interface between the fine twin structure and the matrix. ₃ Mo or Co ₇ Mo ₆ In a method for producing a precipitation-strengthened Co—Ni-based heat-resistant alloy in which is deposited, C: 0.05% or less, Si: 0.5% or less, Mn: 1.0% or less, Ni: 25 to 45%, Cr: 25 to 45% : 13 to 22%, Mo or Mo and W, Mo + 1/2 W: 10 to 18%, Nb: 0.1 to 5.0%, and Fe: 0.1 to 5.0%, and REM: One or more of 0.007 to 0.10%, B: 0.001 to 0.010%, Mg: 0.0007 to 0.010%, and Zr: 0.001 to 0.20% And an alloy containing Ti: 0.1 to 3.0% as needed and the balance consisting of Co and unavoidable impurities is subjected to a solution heat treatment at 1000 to 1200 ° C. By applying aging heat treatment at 600 to 800 ° C under load for 0.5 to 16 hours is there.
[0011]
Further, the fine twin structure of the present invention is formed, and at the same time, Co is formed at the interface between the fine twin structure and the parent phase. ₃ Mo or Co ₇ Mo ₆ In a method for producing a precipitation-strengthened Co—Ni-based heat-resistant alloy in which is deposited, C: 0.05% or less, Si: 0.5% or less, Mn: 1.0% or less, Ni: 25 to 45%, Cr: 25 to 45% : 13 to 22%, Mo or Mo and W, Mo + 1/2 W: 10 to 18%, Nb: 0.1 to 5.0%, and Fe: 0.1 to 5.0%, and REM: One or more of 0.007 to 0.10%, B: 0.001 to 0.010%, Mg: 0.0007 to 0.010%, and Zr: 0.001 to 0.20% And, if necessary, an alloy containing 0.1 to 3.0% of Ti and the balance consisting of Co and unavoidable impurities is subjected to a solution heat treatment at 1000 to 1200 ° C. and then processed. Cold or warm working at a rate of 40% or more, and then 600 to 800 Aging heat treatment of heating to 0.5 ° C. for 0.5 to 16 hours.
[0012]
Further, the fine twin structure of the present invention is formed, and at the same time, Co is formed at the interface between the fine twin structure and the parent phase. ₃ Mo or Co ₇ Mo ₆ In a method for producing a precipitation-strengthened Co—Ni-based heat-resistant alloy in which is deposited, C: 0.05% or less, Si: 0.5% or less, Mn: 1.0% or less, Ni: 25 to 45%, Cr: 25 to 45% : 13 to 22%, Mo or Mo and W, Mo + 1/2 W: 10 to 18%, Nb: 0.1 to 5.0%, and Fe: 0.1 to 5.0%, and REM: One or more of 0.007 to 0.10%, B: 0.001 to 0.010%, Mg: 0.0007 to 0.010%, and Zr: 0.001 to 0.20% And, if necessary, an alloy containing 0.1 to 3.0% of Ti and the balance consisting of Co and unavoidable impurities is subjected to a solution heat treatment at 1000 to 1200 ° C. and then processed. Cold or warm working at a rate of 40% or more, and then exceeding 800 ° C under no load Aging heat treatment of heating to 50 ° C. or lower for 0.5 to 16 hours.
[0013]
[Action]
In the precipitation-strengthened Co—Ni-based heat-resistant alloy of the present invention, fine precipitates are precipitated at the interface between the fine twin structure and the matrix, and these fine precipitates grow even at a high temperature of about 700 ° C. and become coarse. And (2) exerts an effect of effectively fixing dislocations even at a high temperature of 700 ° C. or more because of attractive interaction with dislocations, and (3) a fine twin structure having an average grain size of several microns. At the high temperature of 700 ° C. or higher to suppress the grain boundary sliding as an obstacle at the time of the movement of the grain boundary and to prevent the coarse growth of the crystal grains. It has excellent high-temperature strength.
[0014]
Further, in the method for producing a precipitation-strengthened Co—Ni-based heat-resistant alloy according to the present invention, an aging heat treatment of heating at 600 to 800 ° C. for 0.5 to 16 hours under a stress load state after a solution heat treatment of heating at 1000 to 1200 ° C. Or cold or warm working at a working ratio of 40% or more after the solution heat treatment, followed by aging heat treatment at 600 to 800 ° C. for 0.5 to 16 hours under a stress load state, or After the above solution heat treatment, cold or warm working at a working ratio of 40% or more is performed, and then aging heat treatment of heating at a temperature exceeding 800 ° C. and 950 ° C. or less for 0.5 to 16 hours is performed. A crystal structure is formed, and at the same time, Co is formed at the interface between the fine twin structure and the parent phase. ₃ Mo and / or Co ₇ Mo ₆ Can be precipitated.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, the reason why the component composition is limited as described above in the precipitation-strengthened Co—Ni-based heat-resistant alloy of the present invention and the method for producing the same will be described.
C: 0.05% or less
C combines with Nb and Ti to form carbides, thereby preventing crystal grains from being coarsened during solution heat treatment and contributing to strengthening of grain boundaries, and is an element contained therein. In order to obtain these effects, the content should be preferably 0.005% or more. However, if the content is more than 0.05%, preferably more than 0.03%, toughness and corrosion resistance are reduced and dislocations are fixed. An element to be formed, for example, Mo, forms a carbide to inhibit the effect of fixing dislocations. Therefore, the content is set to 0.05% or less. The preferred range is 0.005 to 0.03%.
[0016]
Si: 0.5% or less
Since Si is effective as a deoxidizing agent, it is an element to be contained therein. However, if it is contained more than 0.5%, preferably more than 0.3%, the toughness is reduced. 5% or less. The preferred content is 0.3% or less.
[0017]
Mn: 1.0% or less
Mn is effective as a deoxidizing agent, and also reduces the stacking fault energy to improve work hardening ability. Therefore, Mn is an element to be contained therein. If contained in excess, the corrosion resistance is reduced, so the content is made 1.0% or less. The preferred content is 0.7% or less.
[0018]
Ni: 25-45%
Ni is an element that stabilizes austenite, which is a matrix, and improves the heat resistance and corrosion resistance of the alloy. To obtain these effects, the content must be 25%, preferably 27% or more. However, if the content exceeds 45%, the work hardening ability is reduced, so the content range is set to 25 to 45%. The preferred content range is 27-45%.
[0019]
Cr: 13 to 22%
Cr is an element to be included for improving heat resistance and corrosion resistance. In order to obtain these effects, it is necessary to contain 13%, preferably 16% or more. However, if it exceeds 22%, preferably 21%, the σ phase is easily precipitated, so the content range is 13 to 22%. And The preferred content range is 16 to 21%.
[0020]
Mo + 1 / 2W: 10 to 18%
Mo and W are elements to be contained for the purpose of forming a solid solution in the matrix and strengthening it and improving the work hardening ability. In order to obtain the effect, it is necessary to contain 10%, preferably 11% or more. When both Mo and W are contained, it is necessary to contain Mo preferably 8.0% or more. Since a phase is precipitated, the content range is set to 10 to 18%. The preferred content range is 11 to 18%.
[0021]
Nb: 0.1 to 5.0%
Nb combines with C to form carbides, thereby preventing crystal grains from coarsening during solution heat treatment and contributing to the strengthening of grain boundaries, and also forming a solid solution in the matrix to strengthen it, thereby causing work hardening. It is an element to be included for improving the performance. To obtain these effects, it is necessary to contain 0.1% or more, preferably 0.8% or more, but if it exceeds 5.0%, preferably 3.0%, the δ phase (Ni ₃ Since Nb) precipitates and lowers workability and toughness, the content range is set to 0.1 to 5.0%. A preferred content range is 0.8 to 3.0%.
[0022]
Fe: 0.1 to 5.0%
Fe is an element contained for the purpose of forming a solid solution in the matrix and strengthening it. In order to obtain the effect, it is necessary to contain 0.1% or more, preferably 0.5% or more. However, if it exceeds 5.0%, preferably 4.8%, the oxidation resistance is reduced. The range is set to 0.1 to 5.0%. The preferred range is 0.5-4.8%.
When Mo, Nb and Fe are used in combination, the solid solution strengthening and work hardening of the matrix are significantly increased and the maximum tensile strength obtained at room temperature and high temperature is significantly increased as compared with the case of using Mo and Nb or Mo and Fe. Also, the effect of increasing the temperature at which the maximum of the tensile strength at a high temperature appears to a high temperature is great.
[0023]
Ti: 0.1 to 3.0%
Ti is an element contained for improving the strength. In order to obtain the effect, it is necessary to contain 0.1%, preferably 0.5% or more. However, if it exceeds 3.0%, preferably 2.5%, the η phase (Ni ₃ Since Ti) precipitates and lowers workability and toughness, the content range is set to 0.1 to 3.0%. A preferred content range is 0.5 to 2.5%.
[0024]
REM: 0.007 to 0.10%
REM, which is one or more of rare earth elements such as Y, Ce, and misch metal, improves hot workability and oxidation resistance, and is an element to be contained for them. In order to obtain these effects, it is necessary to contain 0.007%, preferably 0.01% or more, but if it exceeds 0.10%, preferably 0.04%, on the contrary, hot workability and oxidation resistance Therefore, the content range is set to 0.007 to 0.10%. A preferred content range is 0.01 to 0.04%.
[0025]
B: 0.001 to 0.010%, Mg: 0.0007 to 0.010%, Zr: 0.001 to 0.20%
B, Mg and Zr are elements to be contained for improving hot workability and strengthening grain boundaries. To obtain these effects, B is 0.001%, preferably 0.002% or more, Mg is 0.0007%, preferably 0.001% or more, and Zr is 0.001%, preferably 0.01%. %, But B is 0.010%, preferably 0.006%, Mg is 0.010%, preferably 0.004%, and Zr is 0.20%, preferably 0.05%. %, On the contrary, the hot workability and the oxidation resistance are reduced, so that the content range is as described above. Preferred ranges are 0.002 to 0.006% for B, 0.001 to 0.004% for Mg, and 0.01 to 0.05% for Zr.
[0026]
Co: balance
Co is a close-packed hexagonal lattice, but becomes a face-centered cubic lattice, that is, austenite by containing Ni, and shows high work hardening ability.
[0027]
The precipitation-strengthened Co-Ni-based heat-resistant alloy of the present invention has the above-mentioned composition, and its structure is Co at the interface between the fine twin structure and the parent phase. ₃ Mo or Co ₇ Mo ₆ Are precipitated.
[0028]
Next, a method for producing the precipitation-strengthened Co—Ni-based heat-resistant alloy of the present invention will be described. The method for producing a precipitation-strengthened Co-Ni-based heat-resistant alloy of the present invention produces a fine twinned structure having an average grain size of several microns in a precipitation-strengthened Co-Ni-based heat-resistant alloy having the above-mentioned composition, and At the interface between the fine twin structure and the matrix, Co of several microns to several tens of nanometers ₃ Mo or Co ₇ Mo ₆ Is intended to have high strength by precipitating and to reduce the decrease in strength even when used at a high temperature for a long time.
[0029]
Therefore, the method for producing a Co—Ni-based heat-resistant alloy material of the present invention includes performing a solution heat treatment for heating the above-mentioned Co—Ni-based heat-resistant alloy at 1000 to 1200 ° C., and then increasing the temperature to 600 to 800 ° C. under a stress load state. An aging heat treatment for heating for 0.5 to 16 hours or a solution heat treatment is performed, followed by a cold or warm working at a working ratio of 40% or more, and subsequently to a temperature of 600 to 800 ° C. under a stress load condition. Aging heat treatment for 5 to 16 hours or solution heat treatment, cold or warm working at a working ratio of 40% or more, and then in a range of more than 800 ° C and 950 ° C or less under no load condition Aging heat treatment for heating for 0.5 to 16 hours.
[0030]
The solution heat treatment performed in the method for producing a precipitation-strengthened Co—Ni-based heat-resistant alloy according to the present invention is to homogenize the structure, reduce the hardness, and facilitate the processing, and heat to 1000 to 1200 ° C. It is preferable to carry out. If the temperature is lower than 1000 ° C., not only does not become sufficiently homogenous, but also the hardness does not decrease and processing is difficult. Further, precipitation of compounds such as Mo contributing to the dislocation fixing effect and age hardening caused by the precipitation are reduced. This is because there is a fear. On the other hand, if the temperature exceeds 1200 ° C., the crystal grains become coarse and the toughness and strength are reduced.
[0031]
In the method for producing a precipitation-strengthened Co-Ni-based heat-resistant alloy of the present invention, the aging heat treatment of heating the precipitation-strengthened Co-Ni-based heat-resistant alloy to 600 to 800 ° C for 0.5 to 16 hours under a stress load state is performed. In addition, a fine twin structure having an average particle size of several microns is generated, and Co of several microns to tens of nanometers is formed at the interface between the fine twin structure and the matrix. ₃ Mo or Co ₇ Mo ₆ Is to be precipitated. The load stress in this aging heat treatment is suitably about 100 to 400 MPa. If it is lower than 100 MPa, fine twin structure and fine Co are formed at the interface between the fine twin structure and the parent phase. ₃ Mo or Co ₇ Mo ₆ Is not sufficiently precipitated, and the effect is saturated even if it is higher than 400 MPa, and the alloy subjected to the aging heat treatment is deformed.
[0032]
The aging heat treatment of heating at 600 to 800 ° C. for 0.5 to 16 hours is performed at a temperature lower than 600 ° C., and when the aging heat treatment is performed for less than 0.5 hour, the fine twin structure and the interface between the fine twin structure and the parent phase are formed. Fine Co ₃ Mo or Co ₇ Mo ₆ Is not sufficiently precipitated, and if the temperature exceeds 800 ° C. or exceeds 16 hours, the effect is saturated, and rather, the precipitates are coarsened and the strength is reduced. Further, the working rate is 40% or more. If the aging heat treatment is performed after the cold or warm working, the dislocation is recovered, the hardness and strength are reduced, and the creep elongation is increased.
[0033]
In another method for producing a precipitation-strengthened Co-Ni-based heat-resistant alloy according to the present invention, a cold- or warm-working rate of 40% or more before subjecting the precipitation-strengthened Co-Ni-based heat-resistant alloy to aging heat treatment under a stress load state. The processing is performed to introduce high-density dislocations, and if it is lower than 40%, high-density dislocations cannot be introduced. When aging heat treatment is performed after the introduction of high-density dislocations, solute atoms such as Mo and Fe are segregated into stacking faults formed between the extended dislocation half-dislocations to hinder dislocation motion, thereby relaxing stress, that is, Recovery will be suppressed. As a result, the fine twin structure and fine Co were found at the interface between the fine twin structure and the parent phase. ₃ Mo or Co ₇ Mo ₆ In addition to the effect obtained by the precipitation, a high-strength precipitation-hardened Co-Ni-based heat-resistant alloy having a small decrease in strength even when used at high temperatures for a long time is obtained.
[0034]
In another method for producing a precipitation-strengthened Co—Ni-based heat-resistant alloy according to the present invention, the solution is subjected to solution heat treatment, then to cold or warm working at a working ratio of 40% or more, and then to a temperature exceeding 800 ° C. and 950 ° C. The aging heat treatment of heating for 0.5 to 16 hours at a temperature of not more than 0.5 ° C. generates a fine twin structure having an average particle size of several microns and a few at the interface between the fine twin structure and the matrix. Co from micron to tens of nanometer size ₃ Mo or Co ₇ Mo ₆ Is to be precipitated. In another method of manufacturing a precipitation-strengthened Co-Ni-based heat-resistant alloy different from this method of the present invention, aging heat treatment is performed under a stress load state. However, in this manufacturing method of the present invention, aging is performed under a stress load state. Instead of heat treatment, aging heat treatment is performed in which the temperature is higher than 800 ° C. and lower than 950 ° C. In this manufacturing method, the aging heat treatment at a temperature exceeding 800 ° C. and for 0.5 hour or more is performed at a temperature of 800 ° C. or less and for less than 0.5 hour when the fine twin structure and the interface between the fine twin structure and the parent phase are formed. Fine Co ₃ Mo or Co ₇ Mo ₆ Is not sufficiently precipitated. Also, aging heat treatment at 950 ° C. or less for 16 hours or less means that the effect is saturated even if the aging heat treatment is performed at a temperature higher than 950 ° C. for more than 16 hours, so that solid solution or coarsening of precipitates occurs, Is reduced.
[0035]
As an example of the method for producing the precipitation-strengthened Co—Ni-based heat-resistant alloy of the present invention, an ingot is produced by melting a conventional method using a vacuum high-frequency induction furnace or the like, and casting it by a normal casting method. Thereafter, hot working is performed, a solution heat treatment is performed at 1000 to 1200 ° C., and then an aging heat treatment of heating at 600 to 800 ° C. for 0.5 to 16 hours under a stress load of 100 to 400 MPa or the solution treatment described above is performed. After the heat treatment, cold or warm working at a working ratio of 40% or more is performed, and then aging heat treatment is performed at 600 to 800 ° C. for 0.5 to 16 hours under a stress load of 100 to 400 MPa, or After performing the solution heat treatment, cold or warm working at a working ratio of 40% or more is performed, and then aging heat treatment is performed in a range of more than 800 ° C. and 950 ° C. or less for 0.5 to 16 hours. .
[0036]
The application of the precipitation-strengthened Co—Ni-based heat-resistant alloy of the present invention is performed by using Inconel X750 or Inconel X718 such as an exhaust system component such as an exhaust manifold of an engine, a gas turbine peripheral device, a furnace member, a heat-resistant spring, and a heat-resistant bolt. These are applications that have been used and applications that are used at higher temperatures. In particular, it is suitable for parts such as springs and bolts that are constantly stressed at high temperatures.
[0037]
【Example】
Hereinafter, the present invention will be described with reference to examples.
Example 1
The alloys of the present invention and comparative examples having the component compositions shown in Table 1 below were melted by a normal method using a vacuum high-frequency induction furnace, and cast by a normal casting method to obtain a 50 kg ingot. These ingots were formed into round bars of φ20 mm by hot forging. Thereafter, solution heat treatment was performed at 1100 ° C., and aging treatment was performed at 720 ° C. for 8 hours under a tensile stress of 200 MPa. From these materials, tensile test pieces having a parallel portion of φ8 mm were cut out and subjected to a tensile test at room temperature to measure the tensile strength. In addition, a creep test was performed by cutting out a creep test piece having a parallel portion φ6 mm and a distance between evaluation points of 30 mm, applying a stress of 330 MPa at 700 ° C., and measuring the elongation after 1000 hours. Table 2 shows the results. Table 2 shows the results of identification of precipitates observed in the microstructure.
[0038]
[Table 1]

[0039]
[Table 2]

[0040]
Example 2
Inventive Example No. 1 of Example 1 (Table 1). 5 and No. 5 A solution heat treatment of a 20 mm round bar of the alloy No. 6 at 1100 ° C. and heating at 620 ° C. for 15 hours under a tensile stress of 250 MPa as an example of the present invention, and aging at 720 ° C. for 8 hours under a tensile stress of 200 MPa A heat treatment and an aging treatment of heating at 770 ° C. for 4 hours under a tensile stress of 120 MPa were performed. As comparative examples, aging heat treatment of heating at 850 ° C. × 4 hours under a tensile stress of 80 MPa or aging heat treatment of heating at 550 ° C. × 15 hours under a tensile stress of 250 MPa was performed. A creep test piece similar to that of Example 1 was cut out from these materials, and a creep test was performed under the same conditions as in Example 1 to measure creep. The results are shown in Table 3 below.
[0041]
[Table 3]

[0042]
Example 3
Inventive Example No. 1 of Example 1 (Table 1). 5 and No. 5 A 6 mm round bar of alloy No. 6 was subjected to solution heat treatment at 1100 ° C., and subjected to cold working at a working ratio of 45%, 60% and 75% as an example of the present invention. And the aging heat treatment was performed for the heating time. As a comparative example, after performing cold working at a working ratio of 45%, and then performing aging heat treatment of heating at 770 ° C. × 4 hours without load or cold working at a working ratio of 60%, 720 ° C. × 8 hours at no load An aging heat treatment was performed by heating. A creep test piece similar to that of Example 1 was cut out from these materials, and a creep test was performed under the same conditions as in Example 1 to measure creep. The results are shown in Table 4 below.
[0043]
[Table 4]

[0044]
Example 4
Inventive Example No. 1 of Example 1 (Table 1). 5 and No. 5 A solution bar of φ20 mm of the alloy No. 6 was subjected to solution treatment at 1100 ° C. and cold working at a working rate of 60% and 75% as an example of the present invention, and then 850 ° C. × 4 hours or 920 ° C. × without load. An aging treatment of heating for 2 hours was performed. As a comparative example, after performing cold working at a working ratio of 35%, aging treatment of heating at 920 ° C. × 2 hours without load or cold working at a working ratio of 75%, and then applying 990 ° C. × 2 at no load. An aging treatment of heating for an hour was performed. A creep test piece similar to that of Example 1 was cut out from these materials, and a creep test was performed under the same conditions as in Example 1 to measure creep. The results are shown in Table 5 below.
[0045]
[Table 5]

[0046]
According to these results, the present invention example No. 1 to 7 (Table 2) show that when the structure of the test piece was observed by SEM (scanning electron microscope), a fine twin structure was formed, and fine Co was formed at the interface between the fine twin structure and the matrix. ₇ Mo ₆ Or Co ₃ Mo was precipitated, the room temperature tensile strength was 1121 to 1303 MPa, and the creep elongation was 2.0 to 2.7%. On the other hand, in Comparative Example No. in which Mo + 1/2 W is smaller than in the present invention. Comparative Examples Nos. 1 to 3 and Mo + 1/2 W containing less Nb and Fe than in the present invention. 4 is Co ₇ Mo ₆ Or Co ₃ Mo was not precipitated, and the room temperature tensile strength was 881 to 976 MPa, which was 87% or less of the present invention, and all the test pieces broke in the creep test.
[0047]
Invention Example No. 8 to 13 (Table 3) show that when the structure of the test piece was observed by SEM, a fine twin structure was formed, and a fine Co structure was formed at the interface between the fine twin structure and the matrix. ₃ Mo or Co ₇ Mo ₆ Was precipitated, and the creep elongation in the creep test was 2.0 to 2.9%.
On the other hand, the aging heat treatment temperature was higher than that of the present invention. 5 and Comparative Example No. lower than the present invention. 6 is Co ₃ Mo or Co ₇ Mo ₆ Was not precipitated, and Comparative Example No. In the case of No. 5, the test piece broke in the creep test, and in Comparative Example No. 5; In No. 6, the creep elongation in the creep test was 4.6%, and no improvement in creep strength was observed.
[0048]
Invention Example No. 14 to 22 (Table 4) show that when the structure of the test piece was observed by SEM, a fine twin structure was formed, and a fine Co structure was formed at the interface between the fine twin structure and the parent phase. ₃ Mo or Co ₇ Mo ₆ Are precipitated. 1 and 2 show examples of the present invention. 22 is a structural photograph of No. 22. From this micrograph, Co looks like a block at the interface between the fine twin structure that looks like a regular triangle and the matrix. ₃ Mo or Co ₇ Mo ₆ It can be seen that this is a structure in which is precipitated. Invention Example No. The creep elongation of the creep test of 14 to 22 was 0.9 to 1.9%. These are examples of the present invention in which the creep elongation in the creep test does not undergo cold or warm working of 40% or more before the aging heat treatment. It was smaller than 1 to 13.
On the other hand, in Comparative Example Nos. 7 and No. 7 8 is Co ₃ Mo or Co ₇ Mo ₆ Was not precipitated, and the creep elongation in the creep test was 4.8% and 4.6%, and no improvement in creep strength was observed.
[0049]
Invention Example No. 23 to 28 (Table 5) show that when the structure of the test piece was observed by SEM, a fine twin structure was formed, and a fine Co was formed at the interface between the fine twin structure and the matrix. ₃ Mo or Co ₇ Mo ₆ Was precipitated, and the creep elongation in the creep test was 1.3 to 1.9%. 14-22. On the other hand, in Comparative Example Nos. 9 is Co ₃ Mo or Co ₇ Mo ₆ Was not precipitated, and the creep elongation in the creep test was 4.6%, and no improvement in creep strength was observed. Comparative Example No. 1 in which the aging heat treatment temperature was higher than that of the present invention. In No. 10, the test piece broke during the creep test. Observation of the structure of this test piece revealed a recrystallized structure, and it is considered that the fine twin structure and precipitates disappeared by the aging treatment at 990 ° C.
[0050]
【The invention's effect】
The precipitation-strengthened Co-Ni-based heat-resistant alloy of the present invention has an excellent effect that the strength at room temperature is higher than that of a conventionally used Ni-based super-heat-resistant alloy, and that the strength is not significantly reduced even when used for a long time at a high temperature. To play.
Further, the production method of the present invention is to produce a precipitation-strengthened Co-Ni-based heat-resistant alloy material having a higher strength at room temperature than the above-mentioned Ni-based super-heat-resistant alloy and a small decrease in strength even when used at a high temperature for a long time. It has an excellent effect that it can be performed.
[Brief description of the drawings]
FIG. 1 shows an embodiment of the present invention. It is the scanning electron microscope photograph substituted for the drawing which expanded 22 structures | tissue 5000 times.
FIG. 2 is a scanning electron micrograph as a substitute of a drawing, in which the structure of FIG. 1 is magnified 20000 times.

Claims

By weight% (the same applies hereinafter), C: 0.05% or less, Si: 0.5% or less, Mn: 1.0% or less, Ni: 25 to 45%, Cr: 13 to 22%, Mo or Mo Mo + 1/2 W: 10-18% W: 0.1-5.0% Nb: 0.1-5.0% Fe: REM: 0.007-0.10%, B : 0.001 to 0.010%, Mg: 0.0007 to 0.010%, and Zr: 0.001 to 0.20%, and the balance is Co and unavoidable. consists impurities, fine twins tissue and matrix interface _Co 3 Mo or _Co 7 precipitation strengthened Co-Ni base heat-resistant alloy, wherein the Mo ₆ is precipitated tissue.

C: 0.05% or less, Si: 0.5% or less, Mn: 1.0% or less, Ni: 25 to 45%, Cr: 13 to 22%, Mo + 1/2 W of Mo or Mo and W: 10 -18%, Nb: 0.1-5.0%, Fe: 0.1-5.0%, and Ti: 0.1-3.0%, and REM: 0.007-0.10. %, B: 0.001 to 0.010%, Mg: 0.0007 to 0.010%, and Zr: 0.001 to 0.20%, and the balance is Co. And a structure in which Co ₃ Mo or Co ₇ Mo ₆ is precipitated at the interface between the fine twin structure and the parent phase, and is a precipitation-strengthened Co—Ni-based heat-resistant alloy.

C: 0.05% or less, Si: 0.5% or less, Mn: 1.0% or less, Ni: 25 to 45%, Cr: 13 to 22%, Mo + 1/2 W of Mo or Mo and W: 10 -18%, Nb: 0.1-5.0% and Fe: 0.1-5.0%, REM: 0.007-0.10%, B: 0.001-0.010 %, Mg: 0.0007 to 0.010% and Zr: 0.001 to 0.20%, and heat treatment for solid solution of an alloy containing Co and unavoidable impurities. Thereafter, an aging heat treatment of heating at 600 to 800 ° C. for 0.5 to 16 hours under a stress load state is performed to form a fine twin structure, and at the same time, Co ₃ Mo is formed at the interface between the fine twin structure and the parent phase. or production side of precipitation strengthened Co-Ni base heat-resistant _{alloy Co} 7 Mo ₆ is precipitated .

C: 0.05% or less, Si: 0.5% or less, Mn: 1.0% or less, Ni: 25 to 45%, Cr: 13 to 22%, Mo + 1/2 W of Mo or Mo and W: 10 -18%, Nb: 0.1-5.0%, Fe: 0.1-5.0%, and Ti: 0.1-3.0%, and REM: 0.007-0.10. %, B: 0.001 to 0.010%, Mg: 0.0007 to 0.010%, and Zr: 0.001 to 0.20%, and the balance is Co. And an aging heat treatment of heating the alloy comprising unavoidable impurities to a temperature of 600 to 800 ° C. for 0.5 to 16 hours under a stress load state after the solution heat treatment to form a fine twin structure. _Co at the interface of the crystal structure and the parent phase 3 Mo or _Co 7 Mo ₆ precipitation strengthened was precipitated Co Method for manufacturing a Ni-base heat-resistant alloy.

C: 0.05% or less, Si: 0.5% or less, Mn: 1.0% or less, Ni: 25 to 45%, Cr: 13 to 22%, Mo + 1/2 W of Mo or Mo and W: 10 -18%, Nb: 0.1-5.0% and Fe: 0.1-5.0%, REM: 0.007-0.10%, B: 0.001-0.010 %, Mg: 0.0007 to 0.010% and Zr: 0.001 to 0.20%, and heat treatment for solid solution of an alloy containing Co and unavoidable impurities. Forming a fine twin structure characterized by subjecting to cold or warm working at a working ratio of 40% or more, followed by aging heat treatment at 600 to 800 ° C. for 0.5 to 16 hours under a stress load state; is, _Co 3 simultaneously at the interface of the fine twin structure and the parent phase Mo or _Co 7 Mo Method of manufacturing but precipitated precipitation strengthened Co-Ni base heat-resistant alloy.

C: 0.05% or less, Si: 0.5% or less, Mn: 1.0% or less, Ni: 25 to 45%, Cr: 13 to 22%, Mo + 1/2 W of Mo or Mo and W: 10 -18%, Nb: 0.1-5.0%, Fe: 0.1-5.0%, and Ti: 0.1-3.0%, and REM: 0.007-0.10. %, B: 0.001 to 0.010%, Mg: 0.0007 to 0.010%, and Zr: 0.001 to 0.20%, and the balance is Co. And an alloy consisting of unavoidable impurities is subjected to solution treatment and then to cold or warm working at a working ratio of 40% or more, followed by aging heat treatment at 600 to 800 ° C. for 0.5 to 16 hours under a stress load condition. it was formed a fine twins tissue characterized by, at the same time Co at the interface of the fine twin structure and the parent phase Method for producing a Mo or _Co 7 Mo ₆ is precipitation-strengthened Co-Ni base heat-resistant alloy that precipitated.

C: 0.05% or less, Si: 0.5% or less, Mn: 1.0% or less, Ni: 25 to 45%, Cr: 13 to 22%, Mo + 1/2 W of Mo or Mo and W: 10 -18%, Nb: 0.1-5.0% and Fe: 0.1-5.0%, REM: 0.007-0.10%, B: 0.001-0.010 %, Mg: 0.0007 to 0.010% and Zr: 0.001 to 0.20%, and heat treatment for solid solution of an alloy containing Co and unavoidable impurities. A fine twin structure characterized by subjecting to a cold or warm working at a working ratio of 40% or more, followed by an aging heat treatment of heating over 800 ° C. to 950 ° C. for 0.5 to 16 hours. is formed, _Co 3 simultaneously at the interface of the fine twin structure and the parent phase Mo or _Co 7 M ₆ is a manufacturing method of the deposited precipitation strengthened Co-Ni base heat-resistant alloy.

C: 0.05% or less, Si: 0.5% or less, Mn: 1.0% or less, Ni: 25 to 45%, Cr: 13 to 22%, Mo + 1/2 W of Mo or Mo and W: 10 -18%, Nb: 0.1-5.0%, Fe: 0.1-5.0%, and Ti: 0.1-3.0%, and REM: 0.007-0.10. %, B: 0.001 to 0.010%, Mg: 0.0007 to 0.010%, and Zr: 0.001 to 0.20%, and the balance is Co. And an aging heat treatment in which the alloy comprising unavoidable impurities is subjected to a solution treatment and then subjected to cold or warm working at a working ratio of 40% or more, and subsequently heated at a temperature exceeding 800 ° C. and 950 ° C. for 0.5 to 16 hours. The formation of a fine twin structure characterized by being performed simultaneously with the formation of Co at the interface between the fine twin structure and the matrix. ₃ Mo or manufacturing method of _Co 7 Mo ₆ is precipitated precipitation strengthened Co-Ni base heat-resistant alloy.