JP4127896B2

JP4127896B2 - Liquid phase diffusion bonding method

Info

Publication number: JP4127896B2
Application number: JP13434498A
Authority: JP
Inventors: 倫之中野; 昭宏竹屋
Original assignee: Dai Ichi High Frequency Co Ltd
Current assignee: Dai Ichi High Frequency Co Ltd
Priority date: 1998-04-28
Filing date: 1998-04-28
Publication date: 2008-07-30
Anticipated expiration: 2018-04-28
Also published as: JPH11314167A

Description

【０００１】
【発明の属する技術分野】
本発明は、液相拡散接合によって金属材同志を接合する方法に関する。
【０００２】
【従来の技術】
従来より、棒鋼、鋼管等の金属材の端面同士を突き合わせ接合する方法として、金属材を、接合すべき面同志の間に金属材よりも融点の低いアモルファス材などのインサート材を介在させて突き合わせ、その突き合わせた部分（以下接合系という）をインサート材の融点以上（例えば、１１００〜１３００°Ｃ程度）に加熱、昇温させて、その温度に保持し、溶融したインサート材中のボロン、シリコン等を母材（金属材）に拡散させることによって接合する液相拡散接合方法が知られている。この液相拡散接合方法は、ガス圧接法と比べて低い作業温度で、また、小さい加圧で接合できるため、接合部の大きな変形を伴わずに確実な接合が行えるという利点を有する。
【０００３】
また、鉄筋等の建築現場で用いる条材の端面同志の接合にこの液相拡散接合方法を採用することも知られており、特開平２−２４１６７７号公報に記載されている。この公報に記載の液相拡散接合方法は、条材の端面同志をインサート材を介して突き合わせた接合系に初期圧縮荷重を付加した状態で加熱し、加熱中（昇温及びその後の温度保持期間中）に１回、又は２回以上加圧することを特徴とするもので、この構成により、接合すべき端面の表面の凹凸によって接合部に発生する欠陥を防止でき、また、接合すべき端面の酸化皮膜を破壊、除去して良好な接合部品質を得ることができるというものである。
【０００４】
【発明が解決しようとする課題】
ところが、液相拡散接合を板状の金属材の端面同志の接合に適用したところ、問題のあることが判明した。すなわち、板状の金属材（幅３３４ｍｍ×厚さ１６ｍｍの鋼板）の端面同志を接合すべく、該端面同志をインサート材（アモルファス）を介して突き合わせた接合系に、低い圧縮力（１４．７ＭＰａ）を作用させた状態で加熱し、インサート材の融点以上である１２００°Ｃに昇温させ、その温度に３分間保持して液相拡散接合を行ったところ、図５（ａ）、（ｂ）に示すように、金属材１、２の幅方向の中央部分（二点鎖線で示す部分）は良好に接合して一体化しているが、両端部の１０〜１５ｍｍの領域には、最大間隙が１ｍｍ程度の隙間３が生じており、この領域の接合が不具合となるという問題が生じた。この隙間３の発生原因は、昇温時における熱膨張の、接合面と直角方向の成分が中央部分と両端部で異なる（中央部分が大）ことにより金属材の端面が凸形状に湾曲し、インサート材が溶融する時点では両端部に隙間が生じて接合しなかったためと思われる。
【０００５】
そこで、隙間３をなくすために、インサート材が溶融した時点で接合系に加える圧縮力を増加させ、隙間３の間隔以上のアプセット（圧下量）を加えるという操作を行ったが、アプセットを加える前に、隙間３があった領域における溶融アモルファスが劣化（酸化）し、また、接合すべき面同志の間から流出してしまい、結局、接合後の強度は、他の部分に比べて極端に低く、解決策とはならなかった。
【０００６】
また、特開平２−２４１６７７号公報に記載の方法を応用して、接合系の昇温開始から４０秒経過後に、接合系に作用している圧縮力を４９．０ＭＰａに増加させ、約３０秒間にわたって（接合系が約１１００°Ｃに昇温するまで）、その高い圧縮力に保持するという操作を行ったところ、この場合は、図６（ａ）に示すように、金属材１、２は、その全幅にわたって接合するものの、その断面を見ると図６（ｂ）に示すように、金属材１、２の芯がずれることが多いという問題が発生した。このような芯ずれは頻繁に生じ、且つ芯ずれの大きさｅが、２〜３ｍｍ程度にも及ぶものも多く、無視できないものであった。
【０００７】
本発明は、かかる従来の問題点に鑑みてなされたもので、板状の金属材のように、接合すべき面同志を突き合わせて液相拡散接合する際に、端部に隙間を生じやすい金属材に対しても、隙間を生じることなく、また、大きい芯ずれを生じさせることなく、良好な液相拡散接合を行うことを可能とする液相拡散接合方法を提供することを目的とする。
【０００８】
【課題を解決するための手段】
本発明者等は、接合すべき面同志をインサート材を介して突き合わせた接合系の圧縮力を増加させた際に生じる芯ずれを防止すべく鋭意検討の結果、次の事項を見出した。すなわち、接合系を加熱、昇温させた際、接合系内の温度に、僅かにせよむらが生じ、それによって突き合わせた二つの面に生じる熱膨張にもむらが生じ、突き合わせた面同志が微妙にずれた状態となり、そこに大きい圧縮力を加えると力のバランスがくずれて突き合わせた面同志がずれようとし、そのまま圧縮力を作用させておくと、温度の高い部位ほど塑性変形しやすいことから、突き合わせた面同志のずれが拡大するように塑性変形し（座屈のような状態となり）、これによって大きい芯ずれを生じるが、接合系に加える大きい圧縮力を継続させず、短時間で小さい圧縮力に戻し、次いで再び大きい圧縮力を作用させるという動作を繰り返せば、突き合わせた面同志のずれ方向の塑性変形を抑制して大きな芯ずれを伴わずに、その面の近傍を圧縮方向に塑性変形させて、隙間を無くすことができることを見出し、本発明を完成した。
【０００９】
すなわち、本発明接合方法は、金属材を相手方の金属材と接合すべく、接合すべき面同志をインサート材を介して突き合わせた接合系を、インサート材の融点以上の温度に加熱して接合させる液相拡散接合方法において、前記インサート材が溶融する迄の昇温過程で、前記接合系に対して、接合すべき面と直角方向の圧縮力を接合系の芯ずれ発生を抑制するように短時間ずつ複数回付加して、接合すべき面同志がインサート材を介して互いに密着するように前記接合すべき面の近傍を塑性変形させる構成とし、前記接合系に対して短時間ずつ複数回付加する圧縮力の１回の持続時間を、０．１〜５秒とすることを特徴とする。本発明はこの構成により、突き合わせた面同志の間に熱膨張による隙間が生じやすい接合系においても、大きな芯ずれ発生を伴わずに、インサート材の溶融前に接合すべき面同志をインサート材を介して互いに密着させることができ、この状態でインサート材が溶融して液相拡散接合が行われるため、接合強度が大きく且つ芯ずれの小さい、高品質の接合部を得ることができる。また、接合すべき面に加熱前から多少の凹凸があっても、圧縮力付加による塑性変形によって接合すべき面同志のインサート材を介した密着が確保されるので、高品質の接合部を得ることができる。
【００１０】
【発明の実施の形態】
本発明において、液相拡散接合の対象とする金属材は、液相拡散接合を行うことができるものであれば任意であり、例えば、各種断面形状の型鋼（板材を含む）、棒鋼、鋼管等の端面同志の接合、或いは端面を他の金属材の平坦面（金属板の平坦面、型鋼の側面等）に対して接合する場合等に本発明を適用し得る。特に、接合すべき面の少なくとも一方が、板状の条材、或いは、Ｉ型、Ｌ型、Ｈ型の条材等の、非円形断面の金属条材の端面である場合に本発明を適用することが好ましい。これらの金属条材の端面を接合する場合には、その端面をインサート材をはさんで相手側の面に突き合わせた接合系を加熱した時に、熱膨張によりその端面の端部に隙間を生じることが多く且つ大きい圧縮力を作用させた時には芯ずれを生じやすいので、本発明適用の効果が大きい。
【００１１】
インサート材は、従来の液相拡散接合に使用されているものを適宜使用でき、例えば、Ｆｅ系あるいはＮｉ系のアモルファス材等を例示できる。インサート材の厚さは、接合部材質の母材（金属材）からの偏倚を小とする観点からは薄い方が良く、一方、インサート材の溶融により接合すべき面同志の密接性を高めるという点では厚い方が良く、これらの兼ね合いから、接合すべき面の寸法、精整度或いは用途に応じて、従来提唱されている２０〜１００μｍの範囲を目安に選定すればよい。インサート材を接合すべき面同志の間に介在させる方法としては、箔状のインサート材をはさみ込む方法、箔状のインサート材を接合すべき面に貼り付けておく方法、溶射等によってインサート材を接合すべき面に施しておく方法等を挙げることができる。
【００１２】
金属材の互いに接合すべき面の表面仕上げとしては、油脂等の液相拡散接合に悪影響する物質の除去は必要であるが、表面粗さはさほど小さくする必要はない。本発明では接合面間に圧縮力を作用させて接合面に直角方向の塑性変形を生じさせるので、１〜２ｍｍ程度の凹凸を持った表面粗さは許容しうる。
【００１３】
接合系の加熱方法としては、誘導加熱が好ましい。誘導加熱を採用すると、接合系の狭い領域を敏速に加熱することができ、また、容易にその接合系を、真空、アルゴン、窒素、ヘリウム等の非酸化性雰囲気とすることができ、高品質の液相拡散接合部を形成できるという利点が得られる。
【００１４】
本発明では、接合すべき面同志をインサート材を介して突き合わせた接合系に対して、インサート材が溶融する迄の昇温過程で、前記接合系に対して接合すべき面と直角方向の圧縮力を短時間ずつ複数回付加する。なお、この圧縮力を作用させない時においても、液相拡散接合によって接合面同志が接合するまでの間は、少なくとも、接合すべき面同志が離れないように保持しておくことが必要であり、このため、前記接合系に対して小さい圧縮力を加えておく。以下、説明の便宜上、この低い圧縮力を定常圧縮力と言い、短時間ずつ複数回付加する圧縮力を高位圧縮力と言う。定常圧縮力としては、接合すべき面同志が離れない程度のものであれば、その面の近傍にあまり塑性変形を生じさせないように、小さいことが望ましく、具体的には、５〜２０ＭＰａ程度とすることが好ましい。この定常圧縮力は常時一定に保つものでもよいし、或いは、経時的に変化するもの（例えば、最初に一定のアプセットを与えることで初期圧縮力を付加し、その後はそのアプセット状態に維持することで圧縮力が経時的に減少するもの）でもよい。
【００１５】
接合系に加える高位圧縮力の大きさ、持続時間、回数は、インサート材が溶融する前に、接合すべき面同志の端部に熱膨張等によって生じる隙間を無くし、接合すべき面同志をインサート材を介して互いに密着させるように面の近傍を塑性変形させることができるように選定する。高位圧縮力は大きい程塑性変形を生じやすく、接合すべき面同志をインサート材を介して互いに密着させる効果は増すが、あまり大きくすると芯ずれをもたらす座屈等の好ましくない変形が生じる恐れが拡大する。従って、高位圧縮力の大きさはこれらを考慮し、安定し且つ過大でない圧下速度が得られるよう、２０〜７０ＭＰａ程度に選定することが好ましく、更には、２５〜５０ＭＰａ程度に選定することが一層好ましい。
【００１６】
高位圧縮力を短時間ずつ複数回付加するに当たって、各回の高位圧縮力持続時間は、接合面間に芯ずれが生じたり、接合面間の芯ずれが拡大したりするような座屈の発生を防止しうるように選定するものである。座屈は、高位圧縮力を継続して作用させた場合に、或る程度時間が経過した後に急激に拡大する傾向があるので、その前に高位圧縮力を解除すれば座屈を防止できる。無視しえない程度の座屈が発生するまでの時間は高位圧縮力が大きい程短いが、本発明者等が確認したところ、座屈の生じやすい板状の金属材の端面同志の液相拡散接合に当たって、高位圧縮力を７０ＭＰａとした場合でも、高位圧縮力を加えはじめてから、５秒以内に高位圧縮力を解放すると座屈はほとんど生じなかった。従って、高位圧縮力の持続時間を、５秒以下とすれば、大抵の場合に座屈発生を防止できる。一方、高位圧縮力の持続時間をあまり短くすると、所望の圧下量を得るための圧縮回数が多くなり過ぎて実施が困難となることから、０．１秒以上とすることが好ましい。従って、各回の高位圧縮力持続時間は、０．１〜５秒の範囲に選定することが好ましく、更には、０．３〜３秒程度に選定することが一層好ましい。高位圧縮力の付加終了から次の高位圧縮力付加開始までの休止時間は、特に制限されず、０．１秒程度以上であればよい。
【００１７】
短時間の高位圧縮力を加える回数は、高位圧縮力の大きさ及び１回の高位圧縮力持続時間との兼ね合いを考慮し、接合系に所望の塑性変形を生じさせるように定めればよい。高位圧縮力を複数回付加するに当たって、高位圧縮力の付加間隔（周期）は一定でなくてもよいが、一定とした方が実施が容易となり、好ましい。また、複数回の高位圧縮力を付加する期間は、接合系の加熱開始からインサート材が溶融するまでの昇温期間のうちの一部でもよいが、その昇温期間の大部分とすることが、高位圧縮力を付加する累積時間が長くなり、低い高位圧縮力を用いて接合すべき面同志をインサート材を介して確実に密着させることができ、好ましい。
【００１８】
接合すべき面同志を突き合わせた接合系をインサート材の融点以上に加熱した後は、融点以上の温度に保持して液相拡散接合を行う。この際にも、接合すべき面同志が離れないように、定常圧縮力を加えておくが、インサート材を溶融させた後の適当な時期に、定常圧縮力を越える別途の短時間加圧を行うことも推奨される。このような短時間加圧を行うと、接合すべき面同志を絡ませることができ、また、酸化皮膜の破壊、除去を行うこともでき、接合部の信頼性を一層向上させることができる。この別途の短時間加圧の圧力としても、上記した高位圧縮力と同様の大きさのものを使用できる。また、この場合には、インサート材が溶融状態となり、或る程度液相拡散接合が進んでいるため、接合すべき面同志の間の芯ずれが生じにくく、短時間加圧を継続する時間は、高位圧縮力を加える場合に比べて長く（例えば、１０〜２０秒程度に）することができる。
【００１９】
金属材に圧縮力を付加するための手段としては、公知の機構を適宜使用でき、例えば、油圧シリンダ等の油圧機構を用いたもの、電動モータとねじ機構を用いたもの等を挙げることができる。中でも、油圧機構を用いたものは、容易に所望の圧縮力を所望のタイミングで付与することができるので、好ましい。
【００２０】
【実施例】
以下に、図１に示す装置を用いて鋼板の液相拡散接合を行った結果を示す。図１において、１、２は接合すべき金属材、５は金属材１、２の互いに接合すべき面同志の間にはさんだインサート材、１１は固定台、１２はその固定台１１に金属材２を取り付けるクランプ、１３は可動台、１４はその可動台１３に金属材１を取り付けるクランプ、１５は可動台１３に押圧力を作用させる油圧機構であり、この油圧機構には、押圧力を任意に所望のタイミングで変化させるための制御装置が備えられている。従って、この油圧機構で可動台１３を押し下げることで、金属材１、２の接合系に所望の圧縮力を所望のタイミングで付加することができる。１６は、接合すべき面同志をインサート材５を介して突き合わせた接合系を加熱するための誘導コイル、１７は、接合系を非酸素雰囲気に保持するためのケースである。
【００２１】
〔実施例１〕
図１に示す装置を用い、以下の条件（図２のグラフ参照）で液相拡散接合を行った。なお、以下の説明中、温度は接合系の表面温度である。

【００２２】
上記条件で液相拡散接合を、５０組の金属材について行った結果、すべての場合において、金属材１、２の全幅に渡って良好に接合した接合部が得られた。また、接合した金属材１、２間の芯ずれ量（図６の符号ｅ）を全ての試料について測定したところ、０．１〜０．９ｍｍの範囲内に分布しており、きわめて微小であった。更に、引張試験を行うために、図７に二点鎖線で示すように、液相拡散接合終了後の金属材１、２の幅方向の中央と端部から、ＪＩＳＺ２２０１に規定する１Ａ号試験片に該当する試験片２１を切り出した。試験片２１の寸法は、図８（ａ）、（ｂ）において、厚みｔが１６ｍｍ、破断領域となる平行部の長さＬが２２０ｍｍ、幅Ｗが４０ｍｍである。また、この試験片２１は、接合部の両面に生じているふくらみ２３をそのまま残したものである。更に、このふくらみ２３による影響をなくした引張試験を行うため、図８の試験片２１と同一寸法ではあるが、図９に示すように、接合部の両面のふくらみを除去して平坦とした試験片２１Ａも作成した。各試験片２１、２１Ａをそれぞれ、金属材の中央部と端部のそれぞれについて３個ずつ作成し、ＪＩＳＺ２２４１に規定する試験方法で引張試験を行った。その結果、全ての試験片の破断強度は、５４５〜５５０Ｎ／ｍｍ²の範囲内であり、いずれも、接合部に隣接した母材の部分で破断した。これにより、幅方向の中央も端部も同様に強固に接着していることが確認され、また、接合部の両面のふくらみ２３には、ノッチ等の破断強度を低下させる欠陥が生じていないことが確認された。
【００２３】
次に、曲げ試験を行うために、液相拡散接合終了後の金属材の幅方向の中央と端部から、ＪＩＳＺ２２０４に規定する１号試験片に該当する試験片を切り出し、図１０に示すように、接合部の両面にふくらみを有するままの試験片２５と、そのふくらみを除去して平坦とした試験片をそれぞれ、金属材の中央部と端部についてそれぞれ６個ずつ作成した。この試験片２５の厚さｔは１６ｍｍ、幅Ｗは４０ｍｍ、長さＬは２００ｍｍである。これらの試験片２５について、ＪＩＳＺ３１２２に規定する試験方法で曲げ試験を行った。すなわち、半数の試験片２５については、図１１（ａ）に示すように、その試験片２５の中央の接合部を厚み方向に厚み（１６ｍｍ）の２倍の半径を持ったマンドレル２７で押して、試験片２５を約１８０°折り曲げ、その曲げ外周面に割れが生じるか否かを観測し、残りの試験片２５については、図１１（ｂ）に示すように、その試験片２５を幅方向に幅（４０ｍｍ）の２倍の半径を持ったマンドレル２８を用いて、約１８０°折り曲げ、その曲げ外周面に割れが生じるか否かを観測した。いずれの場合においても、割れは全く見られず、従って良好に接合していることが確認された。
【００２４】
〔実施例２〕
実施例１と同一の鋼板に対して、接合すべき二つの端面の内の一方に、深さ１ｍｍ、幅５ｍｍの溝を、厚み方向の中央に位置し、鋼板の幅方向に延びるように形成し、温度条件は実施例１と同一で、加圧条件はインサート材溶融後の短時間加圧を行わない以外は実施例１と同一で、５組の鋼板について液相拡散接合を行った。その結果、いずれの場合においても、端面に形成していた溝は消え、全体にわたって良好な接合が行われていた。また、厚み方向の芯ずれもほとんど生じていなかった。更に接合後の金属材から、実施例１で説明したのと同様に、引張試験用の試験片を切り出して、引張試験を行ったところ、いずれの試験片もやはり母材の部分で破断し、十分な接合強度を備えていることが確認された。
【００２５】
〔実施例３〕
実施例１と同一の鋼板に対して、接合すべき二つの端面の内の一方の幅方向の中央部に、深さ２ｍｍ、幅５ｍｍの溝を形成し、その他は実施例１と同一条件で、５組の鋼板について液相拡散接合を行った。その結果、いずれの場合においても、端面に形成していた溝は消え、全体に渡って良好な接合が行われていた。また、実施例１で説明したのと同様に、引張試験用の試験片を切り出して、引張試験を行ったところ、いずれの試験片もやはり母材の部分で破断し、十分な接合強度を備えていることが確認された。
【００２６】
〔実施例４〕
図１に示す装置を用い、以下の条件（図３のグラフ参照）で液相拡散接合を行った。

【００２７】
上記条件で３０組の金属材について液相拡散接合を行った。なお、実施例４では金属材１、２の肉厚が大きいため、昇温時に表面温度に比べて内部温度がかなり低くなっており、表面温度が１２００°Ｃに到達した時点でも内部は１１００°Ｃ程度であったため、高位圧縮力の付加を１２００°Ｃ到達時まで継続した。また、１２００°Ｃ到達時点以後においても、表面と内部とに温度差があるため、１回の短時間加圧で累計で６ｍｍに達するアプセット量を生じさせようとすると、温度むらに起因した好ましくない変形を生じるので、短時間加圧を２回に分けて実施した。
【００２８】
液相拡散接合を行った結果、いずれの場合も金属材１、２の全幅に渡って良好に接合した接合部が得られた。また、接合した金属材１、２間の芯ずれ量（図６の符号ｅ）を全ての金属材について測定したところ、０．１〜１．０ｍｍの範囲内に入っていた。次に、実施例１と同様に、接合後の金属材の中央部と端部からそれぞれ、図８、図９に示す引張試験用の試験片２１、２１Ａと同様な試験片を３個ずつ作成した。ただし、この試験片の寸法は、厚みｔが３２ｍｍ、破断領域となる平行部の長さＬが２２０ｍｍ、幅Ｗが２５ｍｍである。これらの試験片について引張試験を行った結果、すべての試験片が母材の部分で破断し、その時の破断強度は、５３６〜５４０Ｎ／ｍｍ²の範囲内に入っていた。これにより、実施例４においても、幅方向の中央も端部も同様に強固に接着していることが確認された。更に、実施例１と同様に、接合後の金属材の中央部と端部からそれぞれ、図１０に示す形状で、厚さｔが３２ｍｍ、幅Ｗが４０ｍｍ、長さＬが２００ｍｍの曲げ試験用の試験片と、接合部両面のふくらみを削除した試験片とをそれぞれ６個ずつ作成し、曲げ試験を行った。その結果、すべての試験片について、割れの発生は見られず、この点からも、幅方向の中央も端部も同様に強固に接着していることが確認された。
【００２９】
〔比較例１〕
実施例１と同一の金属材、インサート材を用いて、実施例１と同一の温度条件で、且つ接合系に加える圧縮力は常に一定の定常圧縮力（１４．７ＭＰａ）として液相拡散接合を行った。その結果、得られた接合部は、図５に示すように、両端から１０〜１５ｍｍの範囲に隙間３が生じていた。
【００３０】
〔比較例２〕
実施例１と同一の金属材、インサート材を用いて、実施例１と同一の温度条件で、且つ接合系に加える圧縮力は、図４に示すように、加熱開始から４０秒後から３０秒間だけ高位圧縮力（４９．０ＭＰａ）とし、その他の期間は一定の定常圧縮力（１４．７ＭＰａ）として、１０個のサンプルについて液相拡散接合を行った。その結果、得られた接合部は、図６に示すように、両端まで接合されていたが、厚み方向に２〜３ｍｍの芯ずれが生じたものが７個もあった。更に、この芯ずれの大きい７個の金属材について、実施例１と同一の引張試験用の試験片を切り出して引張試験を行ったところ、いずれも、破断強度が４００〜４５０Ｎ／ｍｍ²程度であり、且つ接合部で破断していた。
【００３１】
【発明の効果】
以上に説明したように、本発明は、液相拡散接合を行うに際し、接合すべき面同志をインサート材を介して突き合わせている接合系に対して、インサート材が溶融する迄の昇温過程で、接合すべき面に直角方向の圧縮力を短時間ずつ複数回付加したことにより、突き合わせた面同志の間に熱膨張による隙間が生じやすい接合系においても、芯ずれ発生を抑制しながら、インサート材の溶融前に接合すべき面同志をインサート材を介して互いに密着させることができ、従って、接合すべき面の全域を良好に液相拡散接合することができ、接合強度が大きく且つ芯ずれの小さい、高品質の接合部を得ることができるという効果を有している。また、接合すべき面に加熱前から多少の凹凸があっても、圧縮力付加による塑性変形によって接合すべき面同志のインサート材を介した密着が確保されるので、この点からも高品質の接合部を得ることができ、換言すれば、接合すべき面の表面を精密に機械仕上げする必要がなくなり、前処理工程を簡略化できるという効果も有している。
【００３２】
更に、インサート材が溶融した後においても、別途の短時間加圧を行う構成とすると、接合面同志を絡み合わせ、且つ酸化皮膜の破壊、除去を行うことができ、接合部の信頼性を一層向上させることができると共に、接合すべき面に、より大きい凹凸があっても、その凹凸をつぶして良好な接合を行うことができるという効果が得られる。
【図面の簡単な説明】
【図１】（ａ）、（ｂ）はそれぞれ、実施例１〜５における液相拡散接合に用いた装置を、一部を断面で示す概略正面図及び側面図
【図２】実施例１における温度及び圧縮力の経時変化を示すグラフ
【図３】実施例４における温度及び圧縮力の経時変化を示すグラフ
【図４】比較例２における温度及び圧縮力の経時変化を示すグラフ
【図５】（ａ）、（ｂ）はそれぞれ、板状の金属材の端面同志を従来の液相拡散接合方法（比較例１）で接合して得た接合部の概略正面図及び断面図
【図６】（ａ）、（ｂ）はそれぞれ、板状の金属材の端面同志を、上記異なる従来の液相拡散接合方法（比較例２）で接合して得た接合部の概略正面図及び断面図
【図７】実施例１で接合した金属材から試験片を切り出す位置を説明する概略正面図
【図８】実施例１で作成した引張試験用の試験片を示すもので、（ａ）は概略平面図、（ｂ）は概略側面図
【図９】実施例１で作成した引張試験用の試験片の他の例を示す概略側面図
【図１０】実施例１で作成した曲げ試験用の試験片を示すもので、（ａ）は概略平面図、（ｂ）は概略側面図
【図１１】（ａ）、（ｂ）はそれぞれ、曲げ試験を行う状態を示す概略側面図
【符号の説明】
１、２金属材
３間隙
５インサート材
１１固定台
１２クランプ
１３可動台
１４クランプ
１５油圧機構
１６誘導コイル
１７ケース
２１、２１Ａ、２５試験片[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for joining metal materials by liquid phase diffusion joining.
[0002]
[Prior art]
Conventionally, as a method of butt-joining the end faces of metal materials such as steel bars and steel pipes, the metal materials are butt-joined by inserting an insert material such as an amorphous material having a melting point lower than that of the metal material between the surfaces to be joined. Then, the butted portion (hereinafter referred to as a joining system) is heated to a temperature equal to or higher than the melting point of the insert material (for example, about 1100 to 1300 ° C.), held at that temperature, and boron and silicon in the melted insert material A liquid phase diffusion bonding method is known in which bonding is performed by diffusing the material etc. in a base material (metal material). This liquid phase diffusion bonding method has an advantage that reliable bonding can be performed without significant deformation of the bonded portion because bonding can be performed at a lower working temperature and with lower pressure compared to the gas pressure bonding method.
[0003]
It is also known to employ this liquid phase diffusion bonding method for joining end faces of strips used at construction sites such as reinforcing bars, which is described in JP-A-2-241676. In the liquid phase diffusion bonding method described in this publication, heating is performed in a state where an initial compression load is applied to a bonding system in which end faces of strips are abutted via an insert material, and heating is performed (temperature increase and subsequent temperature holding period). This is characterized in that pressurization is performed once or twice or more, and this configuration can prevent defects occurring in the joint due to unevenness of the surface of the end face to be joined. The oxide film can be destroyed and removed to obtain good joint quality.
[0004]
[Problems to be solved by the invention]
However, when liquid phase diffusion bonding was applied to bonding between end faces of a plate-shaped metal material, it was found that there was a problem. That is, a low compression force (14.7 MPa) is applied to a joining system in which end surfaces of each other are joined to each other through an insert material (amorphous) in order to join end surfaces of a plate-shaped metal material (steel plate having a width of 334 mm and a thickness of 16 mm). 5), the temperature was raised to 1200 ° C., which is equal to or higher than the melting point of the insert material, and maintained at that temperature for 3 minutes to perform liquid phase diffusion bonding. ), The central portion (the portion indicated by the two-dot chain line) in the width direction of the

metal materials

1 and 2 is well joined and integrated, but the maximum gap is in the region of 10 to 15 mm at both ends. There is a gap 3 of about 1 mm, which causes a problem that bonding in this region becomes a problem. The cause of the generation of the gap 3 is that the end face of the metal material is curved into a convex shape due to the thermal expansion at the time of temperature rise, the component in the direction perpendicular to the joint surface is different between the central portion and both end portions (large central portion). This seems to be because when the insert material melted, gaps were formed at both ends, and bonding was not performed.
[0005]
Therefore, in order to eliminate the gap 3, the compression force applied to the joining system was increased when the insert material was melted, and an operation was performed to add an upset (a reduction amount) that is greater than the gap 3 interval. In addition, the molten amorphous material in the region where the gap 3 is present deteriorates (oxidizes) and flows out between the surfaces to be joined. As a result, the strength after joining is extremely low compared to other parts. , Did not become a solution.
[0006]
Further, by applying the method described in Japanese Patent Application Laid-Open No. 2-241777, the compression force acting on the joining system is increased to 49.0 MPa after 40 seconds from the start of the temperature rise of the joining system, for about 30 seconds. In this case, as shown in FIG. 6A, the

metal materials

1, 2 are Although bonded over the entire width, as shown in FIG. 6 (b), there is a problem that the cores of the

metal materials

1 and 2 are often misaligned. Such misalignment frequently occurs, and many misalignment magnitudes e are about 2 to 3 mm, which cannot be ignored.
[0007]
The present invention has been made in view of such conventional problems, and is a metal that tends to cause a gap at the end when liquid phase diffusion bonding is performed by matching the surfaces to be joined, such as a plate-shaped metal material. It is an object of the present invention to provide a liquid phase diffusion bonding method that enables good liquid phase diffusion bonding to be performed on a material without generating a gap and without causing a large misalignment.
[0008]
[Means for Solving the Problems]
As a result of intensive studies to prevent misalignment that occurs when the compressive force of the joining system in which the surfaces to be joined are abutted with each other through the insert material, the present inventors have found the following matters. In other words, when heating and raising the temperature of the bonding system, the temperature in the bonding system is slightly uneven, which also causes uneven thermal expansion on the two surfaces that face each other. If a large compressive force is applied to it, the balance of the force will be lost and the faces that are abutted will try to shift.If the compressive force is applied as it is, the higher the temperature, the easier the plastic deformation occurs. , Plastic deformation (buckling state) occurs so that the displacement between the butted surfaces increases, which causes a large misalignment, but does not continue the large compressive force applied to the joining system, and is small in a short time If the operation of returning to the compressive force and then applying a large compressive force again is repeated, the plastic deformation in the misalignment direction between the abutted surfaces is suppressed, and there is no significant misalignment of the surface. Near by plastically deforming the in the compression direction, we found that it is possible to eliminate the gap, thereby completing the present invention.
[0009]
That is, according to the joining method of the present invention, in order to join the metal material to the counterpart metal material, the joining system in which the surfaces to be joined are abutted through the insert material is heated to a temperature equal to or higher than the melting point of the insert material and joined. In the liquid phase diffusion bonding method, in the temperature rising process until the insert material is melted, a compressive force in a direction perpendicular to the surface to be bonded is reduced with respect to the bonding system so as to suppress the occurrence of misalignment of the bonding system. Add several times at a time so that the surfaces to be joined are in close contact with each other via the insert material Should be joined Plastic deformation near the surface It is set as a structure, and the duration of one time of the compressive force applied to the said joining system several times for a short time shall be 0.1 to 5 seconds. It is characterized by that. With this configuration, the present invention allows the insert materials to be joined before melting of the insert material without causing a large misalignment even in a joining system in which a gap due to thermal expansion is likely to occur between the butted surfaces. Since the insert material is melted and liquid phase diffusion bonding is performed in this state, a high-quality bonding portion with high bonding strength and small misalignment can be obtained. Also, even if there are some irregularities on the surfaces to be joined before heating, close contact is ensured through the insert material of the surfaces to be joined by plastic deformation by applying compressive force, so that a high quality joint is obtained. be able to.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
In the present invention, the metal material to be subjected to liquid phase diffusion bonding is arbitrary as long as it can perform liquid phase diffusion bonding. For example, steel plates (including plate materials) having various cross-sectional shapes, steel bars, steel pipes, etc. The present invention can be applied to a case where the end faces are joined together or the end face is joined to a flat face of another metal material (a flat face of a metal plate, a side face of a die steel, etc.). In particular, the present invention is applied when at least one of the surfaces to be joined is an end surface of a metal strip having a non-circular cross section, such as a plate-shaped strip or an I-type, L-type, or H-type strip. It is preferable to do. When joining the end faces of these metal strips, when the joining system in which the end face is abutted against the mating face across the insert material is heated, a gap is created at the end of the end face due to thermal expansion. Since a misalignment is likely to occur when a large amount of compression force is applied, the effect of applying the present invention is great.
[0011]
As the insert material, those used in conventional liquid phase diffusion bonding can be used as appropriate, and examples thereof include an Fe-based or Ni-based amorphous material. The thickness of the insert material should be thin from the viewpoint of minimizing the deviation of the joining material from the base material (metal material), while increasing the closeness of the surfaces to be joined by melting the insert material. In terms of the point, the thicker one is better, and from these considerations, a conventionally proposed range of 20 to 100 μm may be selected according to the size, precision or use of the surfaces to be joined. As a method of interposing the insert material between the surfaces to be joined, a method of sandwiching the foil-like insert material, a method of sticking the foil-like insert material to the surface to be joined, spraying, etc. The method etc. which are given to the surface which should be joined can be mentioned.
[0012]
In order to finish the surfaces of the metal materials to be joined to each other, it is necessary to remove substances that adversely affect liquid phase diffusion joining, such as fats and oils, but it is not necessary to reduce the surface roughness so much. In the present invention, since a compressive force is applied between the joining surfaces to cause plastic deformation in the direction perpendicular to the joining surfaces, a surface roughness having irregularities of about 1 to 2 mm is acceptable.
[0013]
As a heating method for the bonding system, induction heating is preferable. By adopting induction heating, it is possible to quickly heat a narrow area of the bonding system, and to easily make the bonding system into a non-oxidizing atmosphere such as vacuum, argon, nitrogen, helium, etc. The advantage that a liquid phase diffusion bonding portion can be formed is obtained.
[0014]
In the present invention, in a joining system in which the surfaces to be joined are abutted through the insert material, compression in the direction perpendicular to the surface to be joined to the joining system is performed in the temperature rising process until the insert material melts. Apply force multiple times in a short time. Even when this compressive force is not applied, it is necessary to keep at least the surfaces to be joined so as not to leave until the joining surfaces are joined by liquid phase diffusion joining. For this reason, a small compressive force is applied to the joining system. Hereinafter, for convenience of explanation, this low compression force is referred to as a steady compression force, and a compression force applied a plurality of times for a short time is referred to as a high compression force. As the steady compressive force, if the surfaces to be joined are not separated from each other, it is desirable that the compressive force is small so as not to cause much plastic deformation in the vicinity of the surfaces, specifically, about 5 to 20 MPa. It is preferable to do. This steady compressive force may be kept constant at all times, or may change over time (for example, by initially applying a constant upset, an initial compressive force is applied, and then maintained in that upset state. And the compression force decreases with time).
[0015]
The size, duration, and number of high compression forces applied to the joining system are such that, before the insert material melts, the gap between the surfaces to be joined is eliminated by thermal expansion, and the surfaces to be joined are inserted. It selects so that the vicinity of a surface can be plastically deformed so that it may mutually contact | adhere through a material. The higher the higher compressive force, the easier the plastic deformation occurs, and the effect of bringing the surfaces to be joined into close contact with each other through the insert material increases, but the possibility of undesired deformation such as buckling that causes misalignment increases if the force is too large. To do. Accordingly, the magnitude of the high compression force is preferably selected to be about 20 to 70 MPa, and more preferably about 25 to 50 MPa so that a stable and not excessive reduction speed can be obtained in consideration of these. preferable.
[0016]
When applying the high compression force multiple times in a short time, the high compression force duration of each time will cause buckling that may cause misalignment between the joint surfaces or increase the misalignment between the joint surfaces. It is selected so that it can be prevented. Since buckling tends to rapidly increase after a certain amount of time has elapsed when a high compression force is continuously applied, buckling can be prevented by releasing the high compression force before that. The time until buckling that cannot be ignored is shorter as the higher compressive force is larger, but the present inventors have confirmed that liquid phase diffusion between end faces of a plate-like metal material that is likely to buckle. In joining, even when the high compression force was set to 70 MPa, buckling hardly occurred if the high compression force was released within 5 seconds after the high compression force began to be applied. Therefore, if the duration of the high compression force is 5 seconds or less, the occurrence of buckling can be prevented in most cases. On the other hand, if the duration of the high compression force is too short, the number of compressions for obtaining a desired amount of reduction becomes too large, which makes it difficult to carry out. Therefore, the high compression force duration of each time is preferably selected in the range of 0.1 to 5 seconds, and more preferably in the range of about 0.3 to 3 seconds. The pause time from the end of the application of the high compression force to the start of the application of the next high compression force is not particularly limited, and may be about 0.1 seconds or more.
[0017]
The number of times of applying the high-order compression force in a short time may be determined so as to cause desired plastic deformation in the joining system in consideration of the balance between the magnitude of the high-order compression force and the duration of one high-order compression force. In applying the high compression force a plurality of times, the addition interval (cycle) of the high compression force may not be constant, but it is preferable to make it constant because implementation becomes easier. Further, the period during which the high compressive force is applied a plurality of times may be a part of the temperature rising period from the start of heating of the joining system until the insert material melts, but may be the majority of the temperature rising period. The accumulated time for applying the high compressive force becomes long, and the surfaces to be joined using the low high compressive force can be reliably brought into close contact with each other through the insert material, which is preferable.
[0018]
After the joining system in which the surfaces to be joined are abutted to each other is heated to the melting point of the insert material or higher, the liquid phase diffusion bonding is performed while maintaining the temperature above the melting point. Also at this time, a steady compression force is applied so that the surfaces to be joined do not leave, but at a suitable time after the insert material is melted, a separate short-time pressurization exceeding the steady compression force is applied. It is also recommended to do so. When pressure is applied for such a short time, the surfaces to be joined can be entangled, and the oxide film can be destroyed and removed, so that the reliability of the joint can be further improved. As this additional short-time pressurizing pressure, one having the same magnitude as the above-described high-order compression force can be used. In this case, since the insert material is in a molten state and liquid phase diffusion bonding is progressing to some extent, misalignment between the surfaces to be bonded is unlikely to occur, and the time for which pressurization is continued for a short time is It can be made longer (for example, about 10 to 20 seconds) than when a high compression force is applied.
[0019]
As a means for applying a compressive force to the metal material, a known mechanism can be used as appropriate, and examples thereof include a mechanism using a hydraulic mechanism such as a hydraulic cylinder, a mechanism using an electric motor and a screw mechanism, and the like. . Among these, a mechanism using a hydraulic mechanism is preferable because a desired compressive force can be easily applied at a desired timing.
[0020]
【Example】
Below, the result of having performed the liquid phase diffusion joining of the steel plate using the apparatus shown in FIG. 1 is shown. In FIG. 1, 1 and 2 are metal materials to be joined, 5 is an insert material sandwiched between the surfaces of the

metal materials

1 and 2 to be joined, 11 is a fixing base, and 12 is a metal material on the fixing base 11. 2 is a clamp for attaching 2; 13 is a movable base; 14 is a clamp for attaching the metal material 1 to the movable base 13; 15 is a hydraulic mechanism for applying a pressing force to the movable base 13; Is provided with a control device for changing at a desired timing. Therefore, by pushing down the movable table 13 with this hydraulic mechanism, a desired compressive force can be applied to the joining system of the

metal materials

1 and 2 at a desired timing. Reference numeral 16 denotes an induction coil for heating the joining system in which the surfaces to be joined are abutted via the insert material 5, and 17 is a case for maintaining the joining system in a non-oxygen atmosphere.
[0021]
[Example 1]
Liquid phase diffusion bonding was performed using the apparatus shown in FIG. 1 under the following conditions (see the graph of FIG. 2). In the following description, the temperature is the surface temperature of the bonding system.

[0022]
As a result of performing liquid phase diffusion bonding on 50 sets of metal materials under the above conditions, in all cases, a bonded portion was obtained that was bonded well over the entire width of the

metal materials

1 and 2. Further, when the amount of misalignment between the joined metal materials 1 and 2 (symbol “e” in FIG. 6) was measured for all the samples, it was distributed within a range of 0.1 to 0.9 mm and was extremely small. It was. Further, in order to perform a tensile test, as shown by a two-dot chain line in FIG. 7, from the center and the end in the width direction of the

metal materials

1 and 2 after completion of the liquid phase diffusion bonding, the 1A test specified in JIS Z2201 A test piece 21 corresponding to the piece was cut out. 8A and 8B, the test piece 21 has a thickness t of 16 mm, a parallel portion length L of 220 mm, and a width W of 40 mm. Moreover, this test piece 21 leaves the bulge 23 which has arisen on both surfaces of a junction part as it is. Further, in order to conduct a tensile test that eliminates the influence of the bulge 23, the test is the same size as the test piece 21 of FIG. 8, but as shown in FIG. 9, the bulge on both sides of the joint is removed and flattened. A piece 21A was also created. Three

test pieces

21 and 21A were prepared for each of the central portion and the end portion of the metal material, and a tensile test was performed by a test method defined in JIS Z2241. As a result, the breaking strength of all the test pieces is 545 to 550 N / mm. ² In both cases, fracture occurred at the base material adjacent to the joint. As a result, it is confirmed that the center and the end in the width direction are similarly firmly bonded, and the bulges 23 on both sides of the joint are free from defects such as notches that reduce the breaking strength. Was confirmed.
[0023]
Next, in order to perform a bending test, a test piece corresponding to the No. 1 test piece defined in JIS Z2204 is cut out from the center and the end in the width direction of the metal material after completion of liquid phase diffusion bonding, and shown in FIG. In this way, six test pieces 25 having the bulges on both sides of the joint and flat test pieces by removing the bulges were prepared for each of the central part and the end part of the metal material. The test piece 25 has a thickness t of 16 mm, a width W of 40 mm, and a length L of 200 mm. About these test pieces 25, the bending test was done by the test method prescribed | regulated to JISZ3122. That is, about half of the test pieces 25, as shown in FIG. 11A, the central joint of the test piece 25 is pushed with a mandrel 27 having a radius twice as large as the thickness (16 mm) in the thickness direction. The test piece 25 is bent by about 180 °, and it is observed whether or not the bending outer peripheral surface is cracked. For the remaining test pieces 25, as shown in FIG. Using a mandrel 28 having a radius twice the width (40 mm), it was bent about 180 °, and it was observed whether or not a crack occurred on the outer peripheral surface of the bend. In any case, no cracks were observed, and therefore, it was confirmed that the bonding was good.
[0024]
[Example 2]
For the same steel plate as in Example 1, a groove having a depth of 1 mm and a width of 5 mm is formed in one of two end faces to be joined so as to extend in the width direction of the steel plate. The temperature conditions were the same as in Example 1, and the pressurization conditions were the same as in Example 1 except that the pressurization was not performed for a short time after melting the insert material. Liquid phase diffusion bonding was performed on five sets of steel sheets. As a result, in any case, the groove formed on the end face disappeared and good bonding was performed throughout. Further, there was almost no misalignment in the thickness direction. Furthermore, from the metal material after joining, as explained in Example 1, when a test piece for a tensile test was cut out and a tensile test was performed, any test piece was also broken at the base material portion, It was confirmed that it has sufficient bonding strength.
[0025]
Example 3
For the same steel plate as in Example 1, a groove having a depth of 2 mm and a width of 5 mm is formed at one of the widthwise central portions of the two end surfaces to be joined, and the other conditions are the same as in Example 1. Liquid phase diffusion bonding was performed on five sets of steel plates. As a result, in any case, the groove formed on the end face disappeared and good bonding was performed throughout. Further, as described in Example 1, when a tensile test specimen was cut out and a tensile test was performed, all the test specimens were also broken at the base material portion and provided with sufficient bonding strength. It was confirmed that
[0026]
Example 4
Liquid phase diffusion bonding was performed using the apparatus shown in FIG. 1 under the following conditions (see the graph of FIG. 3).

[0027]
Liquid phase diffusion bonding was performed on 30 sets of metal materials under the above conditions. In Example 4, since the thickness of the

metal materials

1 and 2 is large, the internal temperature is considerably lower than the surface temperature when the temperature is raised, and even when the surface temperature reaches 1200 ° C., the inside is 1100 °. Since it was about C, the addition of the high compression force was continued until reaching 1200 ° C. In addition, even after the time of reaching 1200 ° C, there is a temperature difference between the surface and the inside, so if an upset amount that reaches a total of 6 mm is generated by one short pressurization, it is preferable due to temperature unevenness. Since no deformation occurred, pressurization was performed twice in a short time.
[0028]
As a result of performing liquid phase diffusion bonding, in both cases, a bonded portion was obtained that was bonded well over the entire width of the

metal materials

1 and 2. Moreover, when the amount of misalignment (symbol e in FIG. 6) between the joined

metal materials

1 and 2 was measured for all the metal materials, it was within the range of 0.1 to 1.0 mm. Next, in the same manner as in Example 1, three test pieces similar to the

test pieces

21 and 21A for the tensile test shown in FIGS. 8 and 9 are respectively prepared from the central part and the end part of the joined metal material. did. However, the dimensions of this test piece are a thickness t of 32 mm, a length L of a parallel portion serving as a fracture region, 220 mm, and a width W of 25 mm. As a result of performing a tensile test on these test pieces, all the test pieces were broken at the base material portion, and the breaking strength at that time was 536 to 540 N / mm. ² Was in the range. Thereby, also in Example 4, it was confirmed that the center and edge part of the width direction were adhere | attached firmly similarly. Further, in the same manner as in Example 1, from the central portion and the end portion of the metal material after joining, each having the shape shown in FIG. 10, the thickness t is 32 mm, the width W is 40 mm, and the length L is 200 mm. Each of the six test pieces and six test pieces from which the bulges on both sides of the joint were removed were subjected to a bending test. As a result, no cracks were observed in all the test pieces, and from this point, it was confirmed that the center and the end in the width direction were similarly firmly bonded.
[0029]
[Comparative Example 1]
Using the same metal material and insert material as in Example 1, the compression force applied to the joining system under the same temperature conditions as in Example 1 is always a constant steady compression force (14.7 MPa) for liquid phase diffusion bonding. went. As a result, as shown in FIG. 5, the obtained joint had gaps 3 in the range of 10 to 15 mm from both ends.
[0030]
[Comparative Example 2]
Using the same metal material and insert material as in Example 1, the compressive force applied to the joining system under the same temperature conditions as in Example 1 was 30 seconds after 40 seconds from the start of heating, as shown in FIG. Only the high compression force (49.0 MPa) was used, and the liquid phase diffusion bonding was performed on 10 samples with a constant steady compression force (14.7 MPa) for the other periods. As a result, as shown in FIG. 6, the obtained joined portion was joined to both ends, but there were seven that were misaligned by 2 to 3 mm in the thickness direction. Furthermore, about the seven metal materials with large misalignment, when the same tensile test specimen as in Example 1 was cut out and subjected to a tensile test, all had a breaking strength of 400 to 450 N / mm. ² And was broken at the joint.
[0031]
【The invention's effect】
As described above, the present invention is a temperature rising process until the insert material melts with respect to the joining system in which the surfaces to be joined are abutted with each other through the insert material when performing liquid phase diffusion bonding. In addition, by applying a compression force in the direction perpendicular to the surfaces to be joined several times in a short time, even in joining systems where gaps due to thermal expansion are likely to occur between the butted surfaces, The surfaces to be joined can be brought into close contact with each other through the insert material before the material is melted. Accordingly, the entire surface to be joined can be satisfactorily liquid-phase diffusion joined, the joining strength is high, and the misalignment is achieved. It has the effect that a small and high quality joint can be obtained. In addition, even if there are some irregularities on the surfaces to be joined before heating, close contact is ensured through the insert material of the surfaces to be joined by plastic deformation due to the addition of compressive force. A joint can be obtained, in other words, there is no need to precisely machine the surfaces to be joined, and the pretreatment process can be simplified.
[0032]
Furthermore, even after the insert material is melted, if it is configured to perform additional pressurization for a short time, the joint surfaces can be intertwined, and the oxide film can be destroyed and removed, further increasing the reliability of the joint. In addition to being able to improve, even if there are larger irregularities on the surfaces to be joined, the effect can be obtained that the irregularities can be crushed and good bonding can be performed.
[Brief description of the drawings]
FIGS. 1A and 1B are a schematic front view and a side view, respectively, showing a part of the apparatus used for liquid phase diffusion bonding in Examples 1 to 5 in section.
FIG. 2 is a graph showing changes over time in temperature and compressive force in Example 1.
FIG. 3 is a graph showing changes over time in temperature and compressive force in Example 4;
4 is a graph showing changes over time in temperature and compressive force in Comparative Example 2. FIG.
FIGS. 5A and 5B are a schematic front view and a cross-sectional view of a joint obtained by joining end faces of a plate-shaped metal material by a conventional liquid phase diffusion joining method (Comparative Example 1), respectively.
FIGS. 6A and 6B are schematic front views of joints obtained by joining the end faces of a plate-shaped metal material by the different conventional liquid phase diffusion joining methods (Comparative Example 2), respectively. And sectional view
7 is a schematic front view for explaining a position where a test piece is cut out from the metal material joined in Example 1. FIG.
FIGS. 8A and 8B show a specimen for a tensile test created in Example 1, wherein FIG. 8A is a schematic plan view, and FIG. 8B is a schematic side view.
FIG. 9 is a schematic side view showing another example of the test piece for tensile test created in Example 1;
10A and 10B show a test piece for a bending test created in Example 1, wherein FIG. 10A is a schematic plan view, and FIG. 10B is a schematic side view.
FIGS. 11A and 11B are schematic side views showing a state in which a bending test is performed, respectively.
[Explanation of symbols]
1, 2 Metal material
3 gap
5 Insert material
11 Fixed base
12 Clamp
13 Movable stand
14 Clamp
15 Hydraulic mechanism
16 induction coil
17 cases
21, 21A, 25 Test piece

Claims

In the liquid phase diffusion bonding method in which the joining system in which the surfaces to be joined are abutted through the insert material to join the metal material to the counterpart metal material is heated to a temperature equal to or higher than the melting point of the insert material. In the temperature raising process until the insert material melts, a compressive force in a direction perpendicular to the surface to be joined is applied to the joining system several times at a time so as to suppress the occurrence of misalignment of the joining system, A structure in which the vicinity of the surfaces to be joined is plastically deformed so that the surfaces to be joined are in close contact with each other through the insert material, and the compression force applied once to the joining system several times in a short time is maintained once. A liquid phase diffusion bonding method, wherein the time is 0.1 to 5 seconds .

2. The liquid phase diffusion bonding method according to claim 1 , wherein after the insert material is melted, pressurization is separately performed for a short time of 10 to 20 seconds .

3. The liquid phase diffusion bonding method according to claim 1 , wherein at least one of the surfaces to be bonded by liquid phase diffusion bonding is an end surface of a metal strip having a non-circular cross section .