JP3777020B2

JP3777020B2 - Joining method of metal materials

Info

Publication number: JP3777020B2
Application number: JP12762197A
Authority: JP
Inventors: 隆憲黒木; 裕二柳田
Original assignee: Kuroki Kogyosho Co Ltd
Current assignee: Kuroki Kogyosho Co Ltd
Priority date: 1997-05-16
Filing date: 1997-05-16
Publication date: 2006-05-24
Anticipated expiration: 2017-05-16
Also published as: JPH10314962A

Description

【０００１】
【発明の属する技術分野】
本発明は金属材料部材の固相接合による全面接合に関する。
【０００２】
【従来の技術】
金属部材の接合手段は、溶融接合いわゆる溶接と固相接合とに大別できる。
【０００３】
溶融溶接による接合の場合は、アーク溶接を例に挙げると、対象部材が、板状、丸棒状など、断面形状の如何を問わず、接合部に開先を設けて、その空間を埋めていく形で溶接ビードを積み重ねていく方式である。また、溶融溶接による接合法の一つとして、電子ビーム溶接があるが、この溶接法の場合は、深溶け込み溶接が可能であり厚板の１パス溶接も可能である。
【０００４】
また、固相接合は、各種の拡散接合装置を用いて行われ、比較的小型の部材でよく適用されており、一般に、雰囲気として１０^-3〜１０^-5Ｐａの高真空、あるいは不活性ガス、還元性ガスが採用され、接合面に適当な圧力をかけた状態で、ヒータ、通電、誘導加熱、あるいは摩擦や超音波により、接合界面の温度を接合対象母材の融点以下で、しかも原子の拡散が活発になる温度域として行われる。この拡散接合を行う場合、接合中に母材自身に塑性変形が殆ど起きないようにすることが通常で、たとえ塑性変形が生じても冷間圧接のように顕著ではない。
【０００５】
さらに、この際の加圧方法としては、突合せ一軸負荷によるものが一般的であるが、ＨＩＰにみられるように等方圧を加える場合もある。
【０００６】
またさらに、他の接合法として、冷間で行われる常温接合法あるいは冷間圧接法、爆発圧接法などがあり、加熱しない代りに大きな外力を瞬時に付与して接合界面の密着を得ている。
【０００７】
【発明が解決しようとする課題】
上記従来の全面接合法において、それぞれに以下のような欠点がある。
【０００８】
溶融溶接による全面継溶接では、接合面すなわち継手断面が大面積となると施工が大変である。また電子ビーム溶接では深溶け込み溶接が可能であるが、丸棒状での外周からの溶接では中央部に熱がこもり、ここに凝固欠陥が生じるため、丸棒の全面溶接は一般的には不可能である。この場合、見掛け上溶接部が平板状となるように部材を足した状態で電子ビーム溶接し、溶接後に足した部材部を加工除去して丸棒を得る方法もあるが、出力の大きな装置が必要となり、過大なコストがかかる結果となる。
【０００９】
固相接合による全面接合については、雰囲気制御や加圧が必要であり、接合面が密着するように負荷を加え、あるいは治具で拘束する場合、例えば一軸加圧であれば加圧能力、ＨＩＰであれば処理室寸法など、装置の能力による制約を受け、接合面積の大きさについては限界があり、処理物が大型化すると処理できない。
【００１０】
本発明において解決すべき課題は、比較的大型の部材について、接合面の全面を溶融溶接することなく、また接合面に垂直に接合界面を密着させるような適当な負荷あるいは圧力などの外力を加えたり、あるいは治具を用いての拘束をすることなく、金属材料の拡散接合を行い、完全な全面接合を行う方法を見いだすことにある。
【００１１】
【課題を解決するための手段】
本発明は、被接合材の接合面の外周部のみを溶融接合することで接合面を閉塞拘束状態とし、溶融接合されていない残部の接合面を、垂直に接合界面を密着させるような適当な負荷あるいは圧力などの外力を加えたり、あるいは治具を用いて拘束することのない、加圧されない状態で、高温で加熱処理して拡散接合することを特徴とする。
【００１２】
接合部の外周のみを溶融接合することで、その内面は、閉塞拘束されて真空状態に保たれ、この状態を維持することで接合面の拡散接合が達成される。
【００１３】
なお、拡散接合された接合面は、必ずしも接合面全面である必要はなく、製品によってその一部が接合されている場合でも、その接合による強度が特定用途にとって充分な場合には製品として実用に供されるもので、この場合も本願発明の技術的範囲である。
【００１４】
【発明の実施の形態】
本発明の実施の形態は以下のとおりである。
【００１５】
外周部のみの溶融接合：
適用する溶融接合としては、周知の高真空電子ビーム溶接が好適である。この溶接による溶け込み深さは、接合面の全面接合を行うのであれば、丸棒の場合、半径の２５％以上を電子ビーム溶接によって溶融溶接することが望ましい。この溶接による溶け込み深さが浅すぎると接合面の中央部で接合後の剥離が生じることがある。
【００１６】
また特公昭５８−５９６２号公報に示されるように、閉塞拘束された接合面内に残存する大気或いは不活性ガスが高温処理時に母材中へ拡散浸透し得るもので、かつその量が母材の固溶限未満である場合には、接合面内に大気或いは不活性ガスが残存するような一般的な溶接法によって接合面の外周部を溶融溶接する方法でも、ある程度の部分的な接合が可能である。これは鉄基、ニッケル基を始めとする多くの金属材料で可能である。ただし、一般的な溶接法では、とくに異材接合の場合には、完全な閉塞拘束となりうる溶接部を得るためには施工法上での難点も数多く生じ、健全な接合を得るためには、真空雰囲気中で、深溶け込み溶接が容易に行なえる、電子ビーム溶接法が最適である。
【００１７】
適用可能な材質：
本発明が適用できる金属材料としては、軟鋼、炭素鋼、合金鋼あるいはステンレス鋼などの鉄鋼材料、銅、ニッケル及びその合金などの非鉄金属など、通常の拡散接合可能な金属材料であれば、同種・異種を問わず、適用が可能である。直接電子ビーム溶接することができる材料の組み合わせはもちろんのこと、電子ビーム溶接により直接異材溶接ができない材料の組み合わせについても、接合部外周に、あらかじめ他の拡散接合法によって作成された、電子ビーム溶接溶け込み深さに相当するリング状のトランジション・ピースを配置して、おのおの同種材同士の電子ビーム溶接を行うことで接合が可能である。
【００１８】
接合可能な素材の断面形状と大きさ：
所定の溶け込み深さの電子ビーム溶接が行えるのであれば、その断面形状については特に制約はなく、丸形、角形、その他の形状について適用が可能である。本発明は、比較的大型素材の全面接合に適した接合法であり、接合面全面の接合を得るにはある程度部材の大きさが必要になる。例えば、外径が７０ｍｍ以下の細かな部材の接合では、接合面の外周寄りの位置で部分的な剥離が生じる場合もある。また素材長さについても、その外径寸法値に比べて極端に短くなると、接合面の中心部で剥離が生じる。これらについては断面ミクロ組織観察において拡散層の存在が確認されており、高温処理時において一旦接合されていたものが、室温への冷却過程において剥離したものと思われる。
【００１９】
しかしながら実際には、必ずしも室温での完全な全面接合が要求されない場合も多い。例えば熱間鍛造或るいは熱間圧延等の前工程として適用するのであれば、室温まで冷却されることなく引き続いて次工程が行われるので、このような剥離の問題は生じない。あるいは部材全体として静的な接合強度のみが要求され、若干の剥離部の存在が問題とならない場合などもあり、これらの用途に適用する場合については、素材の大きさに関する制約は特にない。
【００２０】
接合処理に際しての予備処理：
本発明は、非溶融の固相接合法を適用するものであるから、接合面の粗さについては、通常の拡散接合法と同様に、面粗さを細かくすれば接合強度の向上と、接合温度の低温側への移行が可能となる。そして表面の汚染、油脂等の付着物は除去する必要がある。一般的には接合面は、通常の旋盤加工およびハンドグラインダーによるバフ仕上げ程度の＃６０から＃８０で十分な強度を有する接合が行われる。
【００２１】
さらにまた、接合面へのインサート材の挿入についても、通常の拡散接合方法と同様に行うことが可能である。
【００２２】
高温処理：
この固相接合のためには、大気炉、真空炉、還元炉、不活性雰囲気炉等を用いても、本発明の接合自体に関しては本質的には何ら変わりのない。ただ、大気炉処理の場合、素材外面は当然酸化されるので、必要に応じて酸化層除去のための処理を行なう。
【００２３】
また、この熱処理に際しては、接合部材全体を炉内に入れて加熱する必要はなく、例えば長尺物の場合、接合部周辺のみを所定の条件で加熱する部分的な加熱処理でも一向に構わない。
【００２４】
加熱処理条件は従来の拡散接合法とほぼ同様である。ちなみに炭素鋼やステンレス鋼の場合であれば、例えば１２５０°Ｃ×５時間の保持で良好な接合が行われる。
【００２５】
【実施例】
実施例１
鉄鋼材料として、低炭素鋼Ｓ１７Ｃとオーステナイト系ステンレス鋼ＳＵＳ３０４の異材接合と同材同士の接合を行った。
【００２６】
表１に示す寸法に機械加工した丸棒素材の片端面を、その粗度が＃６０〜８０となるようにハンドグラインダーにて仕上げた。その端面同士を突き合わせ、その外周部を、表１に示す溶け込み深さが得られる条件にて、電子ビーム溶接した。これらの材料を電気炉にて１２５０°Ｃ×５時間の処理を行った。なお、加熱は２００°Ｃ／ｈｒ、冷却は炉冷とし、大気雰囲気で行った。
【００２７】
【表１】

これらの試験片の中央部の、電子ビーム溶接による溶融溶接がなされていなかった部分より、ＪＩＳＺ２２０１８Ａ号試験片に準拠した引張試験片（平行部径：８ｍｍφ）を１〜４本採取し、引張試験を行った結果、表１に示した引張強さ（平均値）が得られた。
【００２８】
実施例２
さらに、本発明の接合法による固相接合を熱間鍛造の前工程として利用した例について示す。
【００２９】
１５０ｍｍ角×２００ｍｍ長さのＳＳ４００とＳＵＳ３０４を突合せて全長４００ｍｍとし、突合せ部の外周全周を電子ビーム溶接した。電子ビーム溶接は溶け込み深さが約２５ｍｍとなるようにした。これをガス炉で１２００°Ｃ（雰囲気温度）に加熱保持した後、外周側より鍛造し、この操作を２回繰り返して外径が１００ｍｍφとなるようにした。得られた接合材の断面を観察した結果、接合界面はＳＵＳ３０４が凸状になり、ＳＳ４００へとせり出した形状となっていた。そして中心側の未溶接部は、全面接合がなされており、拡散層の存在も認められた。同様に加熱と鍛造を６回繰り返して外径が５０ｍｍφとなるようにしたものについても、同様に接合界面は全面にわたって拡散接合がなされていた。このように、本接合法によって接合された界面は、鍛造などの強加工にも十分耐えうる接合強度を有するものであった。
【００３０】
接合面を横方向から鍛造した場合、接合面内に未接合部があると、それがノッチとなり、接合界面で破断が生じる。しかし、本接合法であれば、何ら問題無く鍛造することができた。
【００３１】
実施例３
熱間圧延の前工程として適用した例について説明する。外径約２００ｍｍφ、長さ約６ｍのＳＵＳ３０４の片端面に、同じ外径で長さが約２００ｍｍの軟鋼を、溶け込み深さ約４５ｍｍで電子ビーム溶接した。これを１２５０°Ｃで５時間保持した後、軟鋼側を先頭にして熱間圧延したところ、接合部で破断することなく、数ｍｍの太さまで圧延することができた。
【００３２】
比較例
比較例として、外径１００ｍｍφ、長さ１００ｍｍのＳＳ４００とＳＵＳ３０４を突合せ、全長２００ｍｍとなるように突合せ部の外周を被覆アーク溶接で全周溶接した。なお、開先形状は、深さ１５ｍｍ、６０°とし、溶加棒はＳＵＳ３０９を用いた。これを大気炉に入れ、１２５０°Ｃで５時間保持した。その結果、接合界面の未溶接部は部分的にしか接合がなされておらず、外周寄りの部分では剥離が生じていた。
【００３３】
【発明の効果】
（１）雰囲気保持や加圧機構を伴った特殊な熱処理装置を用いることなく、一般的な加熱装置を用いて十分な強度を有する金属材料の拡散接合を行うことができる。
【００３４】
（２）大気炉で一度に多数の処理が可能となり、処理コストが大幅に低減される。
【００３５】
（３）大面積あるいは長尺物など、大型部材の全面接合が可能となる。
【００３６】
（４）未接合部がないので、次工程で、圧延や鍛造などの強い塑性加工が可能となる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to entire surface bonding of metal material members by solid phase bonding.
[0002]
[Prior art]
Metal member joining means can be broadly divided into fusion joining, so-called welding, and solid phase joining.
[0003]
In the case of joining by fusion welding, taking arc welding as an example, regardless of whether the target member has a cross-sectional shape such as a plate shape or a round bar shape, a groove is provided in the joint portion to fill the space. This is a method of stacking weld beads in a shape. In addition, as one of the joining methods by fusion welding, there is electron beam welding. In this welding method, deep penetration welding is possible and one-pass welding of a thick plate is also possible.
[0004]
Solid phase bonding is performed using various diffusion bonding apparatuses and is often applied to relatively small members. Generally, the atmosphere is a high vacuum of 10 ⁻³ to 10 ⁻⁵ Pa or an inert gas. In the state where reducing gas is used and appropriate pressure is applied to the joining surface, the temperature of the joining interface is below the melting point of the base material to be joined by heater, energization, induction heating, friction or ultrasonic, and atoms. It is performed as a temperature range in which the diffusion of is active. When performing this diffusion bonding, it is normal that plastic deformation hardly occurs in the base metal itself during the bonding, and even if plastic deformation occurs, it is not as remarkable as cold welding.
[0005]
Further, as a pressurizing method in this case, a butt uniaxial load is generally used, but there are cases where isotropic pressure is applied as seen in HIP.
[0006]
Furthermore, other bonding methods include cold room temperature bonding method, cold pressure welding method, explosive pressure welding method, etc., and a large external force is instantly applied instead of heating to obtain adhesion at the bonding interface. .
[0007]
[Problems to be solved by the invention]
Each of the conventional whole surface bonding methods has the following drawbacks.
[0008]
In full-scale joint welding by fusion welding, if the joint surface, that is, the joint cross section becomes a large area, construction is difficult. In addition, deep penetration welding is possible with electron beam welding, but when welding from the outer circumference in the form of a round bar, heat is trapped in the center, and solidification defects occur here, so it is generally impossible to weld a round bar entirely. It is. In this case, there is also a method of obtaining a round bar by electron beam welding in a state where the members are added so that the welded portion appears to be a flat plate, and processing and removing the added member portions after welding. This is necessary and results in excessive costs.
[0009]
For the whole surface bonding by solid phase bonding, atmosphere control and pressurization are necessary, and when applying a load so that the bonding surface is in close contact or restraining with a jig, for example, if it is uniaxial pressurization, the pressure capacity, HIP If so, the size of the bonding area is limited due to restrictions on the capacity of the apparatus such as the dimensions of the processing chamber.
[0010]
The problem to be solved in the present invention is to apply an external load such as an appropriate load or pressure so as to bring the joining interface into close contact with the joining surface without melting and welding the entire joining surface of a relatively large member. In other words, it is possible to find a method of performing a full-surface bonding by performing diffusion bonding of a metal material without restraining with a jig.
[0011]
[Means for Solving the Problems]
In the present invention, only the outer peripheral portion of the joining surface of the material to be joined is melt- bonded so that the joining surface is closed and restrained, and the remaining joining surface that is not melt-bonded is brought into close contact with the joining interface vertically. or an external force, such as load or pressure or not to restrain using a jig, in a state not pressurized, characterized by diffusion bonding by heat treatment at a high temperature.
[0012]
By melt-bonding only the outer periphery of the joint, the inner surface thereof is closed and restrained and kept in a vacuum state, and diffusion bonding of the joint surface is achieved by maintaining this state.
[0013]
Note that the diffusion bonded surface does not necessarily have to be the entire bonded surface, and even if a part of the bonded surface is bonded by a product, if the strength of the bonding is sufficient for a specific application, the bonded surface is practical. In this case, it is also within the technical scope of the present invention.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention are as follows.
[0015]
Melt welding only at the outer periphery:
A well-known high-vacuum electron beam welding is suitable as the melt bonding to be applied. In the case of a round bar, the penetration depth by welding is preferably 25% or more of the radius by fusion welding by electron beam welding in the case of round joints. If the penetration depth by this welding is too shallow, peeling after joining may occur at the center of the joining surface.
[0016]
Further, as disclosed in Japanese Patent Publication No. 58-5962, the atmosphere or inert gas remaining in the confined and constrained joint surface can diffuse and penetrate into the base material during high-temperature treatment, and the amount of the base material is In the case where the temperature is less than the solid solubility limit, even if the outer peripheral portion of the joint surface is melt-welded by a general welding method in which air or inert gas remains in the joint surface, a certain degree of partial joining is possible. Is possible. This is possible with many metal materials including iron and nickel. However, in general welding methods, especially in the case of dissimilar materials joining, there are many problems in construction methods in order to obtain welds that can be completely closed and restrained, and in order to obtain sound joining, vacuum The electron beam welding method is optimal because it allows easy deep penetration welding in an atmosphere.
[0017]
Applicable material:
The metal material to which the present invention can be applied is the same kind as long as it is a normal diffusion-bondable metal material such as mild steel, carbon steel, alloy steel or non-ferrous metal such as stainless steel, copper, nickel and its alloys.・ Applicable regardless of different types. Not only combinations of materials that can be directly electron beam welded, but also combinations of materials that cannot be directly welded to different materials by electron beam welding, electron beam welding was created in advance on the outer periphery of the joint by another diffusion bonding method. Joining is possible by arranging a ring-shaped transition piece corresponding to the penetration depth and performing electron beam welding of the same kind of materials.
[0018]
Cross-sectional shape and size of materials that can be joined:
If electron beam welding with a predetermined penetration depth can be performed, the cross-sectional shape is not particularly limited, and can be applied to round shapes, square shapes, and other shapes. The present invention is a bonding method suitable for the entire surface bonding of relatively large materials, and a certain size of member is required to obtain the entire bonding surface. For example, when a fine member having an outer diameter of 70 mm or less is joined, partial peeling may occur at a position near the outer periphery of the joining surface. Further, if the material length is extremely shorter than the outer diameter dimension value, peeling occurs at the center of the joint surface. Regarding these, the presence of a diffusion layer has been confirmed by observation of the cross-sectional microstructure, and what was once bonded during the high-temperature treatment seems to have peeled off during the cooling to room temperature.
[0019]
In practice, however, full surface bonding at room temperature is not always required. For example, if it is applied as a previous process such as hot forging or hot rolling, the next process is carried out without cooling to room temperature, so that such a peeling problem does not occur. Alternatively, only the static bonding strength is required for the entire member, and the presence of a slight peeling portion may not be a problem. When applied to these applications, there is no particular restriction on the size of the material.
[0020]
Pretreatment for joining process:
Since the present invention applies a non-melting solid phase bonding method, the surface roughness of the bonding surface can be improved by reducing the surface roughness in the same manner as in the normal diffusion bonding method. The temperature can be shifted to the low temperature side. And it is necessary to remove contaminants such as surface contamination and oils and fats. Generally, the joining surfaces are joined with sufficient strength at # 60 to # 80, which is about the level of buffing by ordinary lathe processing and hand grinder.
[0021]
Furthermore, the insertion of the insert material into the joint surface can be performed in the same manner as a normal diffusion bonding method.
[0022]
High temperature treatment:
For this solid phase bonding, even if an atmospheric furnace, a vacuum furnace, a reducing furnace, an inert atmosphere furnace or the like is used, there is essentially no change with respect to the bonding itself of the present invention. However, in the case of atmospheric furnace treatment, the outer surface of the material is naturally oxidized, so that treatment for removing the oxide layer is performed as necessary.
[0023]
In this heat treatment, it is not necessary to heat the entire joining member in a furnace. For example, in the case of a long object, a partial heat treatment in which only the periphery of the joint is heated under a predetermined condition may be used.
[0024]
The heat treatment conditions are almost the same as in the conventional diffusion bonding method. Incidentally, in the case of carbon steel or stainless steel, for example, good bonding is performed by holding at 1250 ° C. × 5 hours.
[0025]
【Example】
Example 1
As the steel material, the same material was joined to the dissimilar material joining of low carbon steel S17C and austenitic stainless steel SUS304.
[0026]
One end face of a round bar material machined to the dimensions shown in Table 1 was finished with a hand grinder so that the roughness was # 60-80. The end faces were butted together, and the outer peripheral portion was subjected to electron beam welding under the condition that the penetration depth shown in Table 1 was obtained. These materials were processed in an electric furnace at 1250 ° C. for 5 hours. Note that heating was performed at 200 ° C./hr, cooling was performed in a furnace, and was performed in an air atmosphere.
[0027]
[Table 1]

1 to 4 tensile test pieces (parallel part diameter: 8 mmφ) conforming to the JIS Z 2201 No. 8A test piece were collected from the central part of these test pieces that were not melt welded by electron beam welding. As a result of the tensile test, the tensile strength (average value) shown in Table 1 was obtained.
[0028]
Example 2
Furthermore, an example in which solid phase bonding by the bonding method of the present invention is used as a pre-process for hot forging will be described.
[0029]
150 mm square × 200 mm long SS400 and SUS304 were butted to a total length of 400 mm, and the entire circumference of the butted portion was electron beam welded. Electron beam welding was performed with a penetration depth of about 25 mm. This was heated and held at 1200 ° C. (atmosphere temperature) in a gas furnace, and then forged from the outer peripheral side, and this operation was repeated twice so that the outer diameter became 100 mmφ. As a result of observing a cross section of the obtained bonding material, the bonding interface had a shape in which SUS304 became convex and protruded to SS400. The unwelded portion on the center side was fully bonded, and the presence of a diffusion layer was also observed. Similarly, in the case of heating and forging repeated 6 times so that the outer diameter becomes 50 mmφ, the bonding interface was similarly diffusion bonded over the entire surface. Thus, the interface joined by this joining method has a joining strength that can sufficiently withstand strong processing such as forging.
[0030]
When the joining surface is forged from the lateral direction, if there is an unjoined portion in the joining surface, it becomes a notch and breaks at the joining interface. However, with this joining method, it was possible to forge without any problems.
[0031]
Example 3
An example applied as a pre-process of hot rolling will be described. To one end face of SUS304 having an outer diameter of about 200 mmφ and a length of about 6 m, mild steel having the same outer diameter and a length of about 200 mm was subjected to electron beam welding with a penetration depth of about 45 mm. After holding this at 1250 ° C. for 5 hours and hot rolling with the mild steel side at the top, it could be rolled to a thickness of several mm without breaking at the joint.
[0032]
Comparative Example As a comparative example, SS400 and SUS304 having an outer diameter of 100 mmφ and a length of 100 mm were butted together, and the outer circumference of the butted portion was welded all around by covering arc welding so as to have a total length of 200 mm. The groove shape was 15 mm deep and 60 °, and the filler rod was SUS309. This was put into an atmospheric furnace and held at 1250 ° C. for 5 hours. As a result, the unwelded portion at the joint interface was joined only partially, and peeling occurred at the portion near the outer periphery.
[0033]
【The invention's effect】
(1) Diffusion bonding of a metal material having a sufficient strength can be performed using a general heating device without using a special heat treatment device with atmosphere holding or a pressure mechanism.
[0034]
(2) A large number of treatments can be performed at once in the atmospheric furnace, and the treatment cost is greatly reduced.
[0035]
(3) Large-scale members such as large areas or long objects can be joined all over.
[0036]
(4) Since there is no unjoined portion, strong plastic working such as rolling or forging can be performed in the next step.

Claims

Appropriate load or pressure that melts and bonds only the outer periphery of the bonding surface of the material to be bonded to bring the bonding surface into a closed constrained state and vertically bonds the remaining bonding surface that is not melt bonded to the bonding interface of or added external force or not to restrain using a jig, in a state not pressurized bonding method Rukin metal material to diffusion bonding by heat treatment at a high temperature.

Method for joining metallic materials according to entire bonding surface to 請 Motomeko 1 joined metallurgically by diffusion bonding.

Method for joining metallic material according to 請 Motomeko 1 Ru least a portion der of the joining surface is diffusion bonding.

Method for joining metallic material according to 請 Motomeko 1 to maintain a vacuum state inside the outer peripheral portion of the molten weld and closure constrained.

Method for joining metallic material according to the line of the Hare請 Motomeko 1 melt bonding by a high-energy beam welding of the outer peripheral portion only.

Penetration depth when melted joining only the outer peripheral portion, the joining method of the metal material according to 請 Motomeko 2 Ru der least 25% of the cross-section radius.

The metal material joining method according to claim 1, wherein the roughness of the joining surface of the materials to be joined is set to # 60 to # 80 in the preliminary treatment .

The metal material joining method according to claim 2, wherein the outer diameter of the material to be joined is greater than 70 mm.

The metal material joining method according to claim 1, wherein a ring-shaped transition piece corresponding to the penetration depth of the high energy beam welding is disposed on the outer periphery of the joining portion, and the high energy beam welding is applied.

The joining method of the metal material of Claim 1 applied as a pre-process of hot forging or hot rolling.

The metal material joining method according to claim 1, wherein an insert material is inserted into the joining surface.