JP3822851B2

JP3822851B2 - Alloy for low melting point iron-based joining

Info

Publication number: JP3822851B2
Application number: JP2002259277A
Authority: JP
Inventors: 有一佐藤; 広明坂本
Original assignee: Nippon Steel Corp
Current assignee: Nippon Steel Corp
Priority date: 2002-04-15
Filing date: 2002-09-04
Publication date: 2006-09-20
Anticipated expiration: 2022-09-04
Also published as: JP2004001065A

Description

【０００１】
【発明の属する技術分野】
本発明は、各種構造物等の鉄基材料を接合するための接合用合金に関するものである。
【０００２】
【従来の技術】
各種構造物等の鉄基材料の接合において、液相拡散接合法が知られている。液相拡散接合は、被接合材の間に被接合材よりも融点の低い接合材を介在させて液相線直上にて加熱し、接合材中の拡散元素を拡散させて接合する方法である。
【０００３】
本発明者らは、酸化雰囲気中での液相拡散接合を実現できる鉄基材料の液相拡散接合用合金箔を発明し、特許出願した（特許文献１参照）。
該合金箔は、Ｐ：１．０〜２０．０原子％、Ｓｉ：１．０〜１０．０原子％、Ｖ：０．１〜２０．０原子％、Ｂ：１．０〜２０．０原子％を含有し、さらに、Ｃｒ、Ｎｉ、Ｃｏ、Ｗ、Ｎｂ、Ｔｉを必要に応じて含有し、残部がＦｅおよび不可避的不純物からなる組成を有し、厚さが３．０〜２００μｍの箔である。
【０００４】
【特許文献１】
特開平９−３２３１７５号公報
【０００５】
またこのような合金箔を製造するための方法として、単ロール法や双ロール法などが知られている。これらの方法は、高速回転する金属製ドラムの外周面に、溶融金属をオリフィスなどから噴出させることにより急速に凝固させて、薄帯を鋳造するものである。合金組成を適正に選ぶことによって液体金属に類似した非晶質合金薄帯を製造することができる。
【０００６】
【発明が解決しようとする課題】
上記特開平９−３２３１７５号公報に開示している液相拡散接合用合金箔を使用した接合において、接合強度の改善が求められた。かかる要求を充すために本発明者らは実験検討を行った結果、接合層の材質を改善すると共に、接合材を低融点化することで接合時の加熱温度を低下させるのが有効であることがわかった。
【０００７】
そこで本発明が解決しようとする課題は、接合材の合金組成を最適化することで、接合層の材質を改善すると共に、より低温での接合を可能にして、接合強度を向上できる低融点接合用の合金を提供することである。
【０００８】
【課題を解決するための手段】
上記課題を解決するための本発明は、原子％にて、Ｂ：６％以上１４％以下、Ｓｉ：２％未満、Ｃ：２％以上６％以下、Ｐ：１％以上２０％以下を含有し、残部がＦｅおよび不可避的不純物からなり、非晶質でかつ融点が１１００℃以下であることを同時に満足することを特徴とする鉄系低融点接合用の合金である。
【０００９】
また本発明は、さらに、原子％にて、Ｎｉ：０．１％以上２０％以下と、Ｃｒ：０．１％以上２０％以下と、Ｖ：０．１％以上１０％以下の少なくとも１種を含有し、残部がＦｅおよび不可避的不純物からなり、非晶質でかつ融点が１１００℃以下であることを同時に満足することを特徴とする鉄系低融点接合用の合金である。
【００１０】
【発明の実施の形態】
本発明の接合用合金は、接合層の材質改善および低融点化の観点から組成を限定している。合金の融点は成分組成によって一義的に決まるが、接合層の材質改善を考慮して組成を限定している。さらに本発明の接合用合金は非晶質の箔状で使用することが特に有効であり、薄帯鋳造時における非晶質形成能の観点からも組成を限定している。なお、非晶質は箔全体に形成されなくてもよい。
【００１１】
接合部の材質改善については、十分な接合強度が得られなかった材料の接合部組織を観察した結果、接合層にＳｉＯ₂が生成し、これを基点に割れが発生しているのが認められた。このＳｉＯ₂は接合材中のＳｉによることがわかり、接合用合金のＳｉ含有量を低減することとした。しかし、Ｓｉは合金の非晶質化にとって重要な元素であるため、これを低減しても所要の非晶質化を達成できる総合的な成分組成を求めた。以下に成分限定理由を述べる。
【００１２】
Ｓｉは、接合層のＳｉＯ₂生成を抑えるために２原子％未満とした。Ｓｉを添加しなくてもよい。これによる非晶質形成能の低下は、下記他の成分、特にＣによって補うことができる。
【００１３】
Ｂ、Ｐ、Ｃは非晶質化を実現し、かつ融点が１１００℃以下となるためにその含有量を限定した。
Ｂは、６原子％未満では非晶質形成が困難となる。１４原子％超では低融点化効果がなくなるばかりでなく、接合部に硼化物を生成し接合強度を低下させる。したがってＢ含有量を６原子％以上１４原子％以下とした。
【００１４】
Ｐは、１〜２０原子％の範囲で良好な低融点化効果を示す。１原子％未満ではこの効果は得られず、２０原子％超になるとさらなる添加効果は得られなくなるばかりか、良好な箔の形成が困難となる。したがってＰ含有量を１原子％以上２０原子％以下とした。
【００１５】
Ｃは、本発明で重要な役割をなす元素である。つまりＳｉを低減したことによる非晶質形成能の低下を、主としてＣで代替する。このため２原子％以上添加する。含有量は６原子％までで十分であり、６原子％を超えてもさらなる添加効果は得られない。またＣは薄帯の鋳造性に効果のある元素である。すなわち、上記範囲で溶融合金と冷却基板との濡れ性が向上し、冷却速度が高くなり良好な非晶質化が達成できる。したがってＣ含有量を２原子％以上６原子％以下とした。
【００１６】
Ｎｉは、主として低融点化効果があり必要に応じて添加する。０．１原子％未満ではその効果が不十分であり、２０原子％を超えるとこの効果が得られなくなる。したがって、Ｎｉ含有量を０．１原子％以上２０原子％以下とした。
【００１７】
Ｃｒは、主として耐食性、耐酸化性を高めるために必要に応じて添加する。０．１原子％未満ではその効果が不十分であり、２０原子％を超えると融点が１１００℃を超えるようになってしまう。したがってＣｒ含有量を０．１原子％以上２０原子％以下とした。
【００１８】
Ｖは、被接合表面の酸化被膜形成物質を低融点物質にする効果がある。例えばＦｅ₂Ｏ₃を、融点が約８００℃の低融点複合酸化物Ｖ₂Ｏ₅−Ｆｅ₂Ｏ₃にする効果があり、本発明合金を使用した場合、接合温度９００〜１１００℃で酸化被膜が溶融する。液相中では表面張力の差によって球状化するので、Ｂ、Ｓｉ、Ｐ等の拡散元素が自由に拡散し、酸化雰囲気中でも液相拡散接合を達成できる。Ｖ含有量が０．１原子％未満ではこの効果が不十分であり、１０原子％超では融点が１１００℃を超えるようになる。したがってＶ含有量を０．１原子％以上１０原子％以下とした。
Ｖを添加することにより酸化雰囲気中での接合が可能となるが、本発明のＶ添加合金は、酸化雰囲気用に限定されるものではない。
【００１９】
上記元素以外の残部はＦｅおよび不可避的不純物からなる。不可避的不純物としては、Ｍｎ、Ｓ等を０．２原子％程度まで含有しても特段の問題はない。
【００２０】
本発明の接合用合金は、液相拡散接合のみならず、いわゆるロウ付け、あるいはロウ接とよばれる接合法にも使用できる。この接合法は一般的に、接合材が溶融したのち、接合材中の拡散元素Ｂ、Ｓｉ、Ｐ等が被接合材中に拡散する前に固化して接合する方法である。
【００２１】
また本発明の接合用合金は、急冷凝固法として知られている単ロール法や双ロール法等により薄帯に鋳造し、箔状の接合材として使用することができる。また形状としては箔のほか、用途に応じて粉末等も使用することができる。さらに、非晶質に限らず、結晶質のものでも用途によっては使用可能である。
【００２２】
【実施例】
表１に示す各合金について、単ロール法により下記条件で箔を鋳造した。表２に融点および接合実験の結果を示す。各合金は、いずれも、Ｍｎ、Ｓ等の不純物を０．２原子％含んでいる。鋳造時の溶融合金温度は、表２に示す融点よりおよそ１５０℃高い温度とした。

【００２３】
各合金の融点はＤＴＡ装置により求めた。表２に示すように、本発明例はいずれも１１００℃以下であったが、比較例は大半が１１００℃を超えるものであった。
【００２４】
鋳造結果、比較例のＮｏ．３３、Ｎｏ．３４、Ｎｏ，４１、Ｎｏ．４７は良好な箔が得られず、以後の接合実験を行うことができなかった。それ以外は、本発明例、比較例とも問題なく鋳造でき、板厚が２５μｍ程度の良好な箔が得られた。
【００２５】
得られた箔を用いて接合実験を行い、接合後に接合強度を測定した。接合実験に際しては、直径２０ｍｍの円盤状にした箔２枚を重ねて接合材とし、直径２０ｍｍのＳＴＫ４００の丸鋼を被接合材とした。図１に示すように、２本の被接合材１の間に接合材２を挟みこんで接合した。接合温度は、各合金の融点直上から融点＋５０℃の範囲として、雰囲気制御可能な加熱炉を用いて表２に示すそれぞれの雰囲気で加熱した。加熱中は、被接合材１と接合材２の密着性を高めるため２ＭＰａで加圧した。接合時間はすべて１０分とした。
【００２６】
そして、図２に示すように、接合後の丸鋼３から接合線４を中心としてＪＩＳＡ２号引張試験片５を切り出し、ＪＩＳＡ２号引張試験機を用いて引張試験を行った。また、接合実験前の被接合材２の母材からも同試験片を切り出して同様に引張試験を行い、接合強度を対母材比（接合部強度）／（母材強度）で表２に示した。
【００２７】
本発明例は、いずれも対母材比で１．０を超える高い接合強度が得られた。これは、Ｓｉ含有量を低減した接合用合金を接合材としたことによりＳｉＯ₂の生成を抑制したため、および融点の低い合金を接合材としことで接合温度を低くすることができ接合部の熱影響部の強度劣化を抑制できたためと考えられる。
【００２８】
これに対して、比較例はいずれも対母材比で０．９１以下であり、満足できる接合強度が得られなかった。これは接合部にＳｉＯ₂が生成したことと、接合材の融点が高かったため、接合温度を高くしなければならず、その分熱影響部の強度が劣化したためと考えられる。
【００２９】
【表１】

【００３０】
【表２】

【００３１】
【発明の効果】
本発明の低融点接合用合金は、Ｓｉ含有量を低減することにより接合層の材質を改善するとともに、成分組成を最適化して融点を１１００℃以下としてより低温での接合が可能となった。このため、対母材比で１．０を超える高い接合強度が安定して得られる。したがって、被接合材の特性を損なうことのない接合が可能となり、さらに、加熱温度低下により接合コストの削減も可能である。
【図面の簡単な説明】
【図１】実施例における接合実験の説明図である。
【図２】実施例における引張試験片の説明図である。
【符号の説明】
１：被接合材２：接合材
３：接合後の丸鋼４：接合線
５：引張試験片[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a joining alloy for joining iron-based materials such as various structures.
[0002]
[Prior art]
A liquid phase diffusion bonding method is known for bonding iron-based materials such as various structures. Liquid phase diffusion bonding is a method in which a bonding material having a melting point lower than that of the material to be bonded is interposed between the materials to be bonded and heated immediately above the liquidus line to diffuse and diffuse the diffusion elements in the bonding material. .
[0003]
The inventors have invented an iron-based material liquid phase diffusion bonding alloy foil capable of realizing liquid phase diffusion bonding in an oxidizing atmosphere, and filed a patent application (see Patent Document 1).
The alloy foil has P: 1.0 to 20.0 atomic%, Si: 1.0 to 10.0 atomic%, V: 0.1 to 20.0 atomic%, and B: 1.0 to 20.0. Containing atomic%, further containing Cr, Ni, Co, W, Nb, Ti as required, with the balance being composed of Fe and inevitable impurities, and having a thickness of 3.0 to 200 μm It is a foil.
[0004]
[Patent Document 1]
Japanese Patent Laid-Open No. 9-323175
As a method for producing such an alloy foil, a single roll method or a twin roll method is known. In these methods, a thin ribbon is cast by rapidly solidifying molten metal from an orifice or the like on an outer peripheral surface of a metal drum that rotates at high speed. By appropriately selecting the alloy composition, an amorphous alloy ribbon similar to a liquid metal can be produced.
[0006]
[Problems to be solved by the invention]
In the joining using the alloy foil for liquid phase diffusion bonding disclosed in the above-mentioned JP-A-9-323175, improvement in bonding strength has been demanded. In order to satisfy this requirement, the present inventors have conducted an experimental study, and as a result, it is effective to improve the material of the bonding layer and lower the heating temperature during bonding by lowering the melting point of the bonding material. I understood it.
[0007]
Therefore, the problem to be solved by the present invention is to improve the bonding strength by optimizing the alloy composition of the bonding material to improve the material of the bonding layer and enable bonding at a lower temperature. Is to provide an alloy for the use.
[0008]
[Means for Solving the Problems]
The present invention for solving the above-mentioned problems contains, in atomic%, B: 6% to 14%, Si: less than 2%, C: 2% to 6%, P: 1% to 20% and, the balance being Fe and inevitable impurities, an alloy for an iron-based low-melting bonding, characterized by satisfying simultaneously the amorphous and and a melting point of 1100 ° C. or less.
[0009]
The present invention further includes at least one of Ni: 0.1% to 20%, Cr: 0.1% to 20%, and V: 0.1% to 10% in atomic%. An iron-based low-melting-point bonding alloy characterized in that it contains, at the same time, the balance of Fe and inevitable impurities, which is amorphous and has a melting point of 1100 ° C. or lower.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
The alloy for bonding of the present invention has a limited composition from the viewpoint of improving the material quality of the bonding layer and lowering the melting point. The melting point of the alloy is uniquely determined by the component composition, but the composition is limited in consideration of the material improvement of the bonding layer. Furthermore, it is particularly effective to use the bonding alloy of the present invention in the form of an amorphous foil, and the composition is also limited from the viewpoint of the ability to form an amorphous film at the time of ribbon casting. Note that the amorphous material does not have to be formed on the entire foil.
[0011]
As for the material improvement of the joint part, as a result of observing the joint structure of the material for which sufficient joint strength was not obtained, it was found that SiO ₂ was generated in the joint layer, and cracking occurred based on this. It was. This SiO ₂ was found to be due to Si in the bonding material, and the Si content of the bonding alloy was reduced. However, since Si is an important element for the amorphization of the alloy, a comprehensive component composition that can achieve the required amorphization even if this element is reduced was sought. The reasons for limiting the components will be described below.
[0012]
Si was made less than 2 atomic% in order to suppress generation of SiO ₂ in the bonding layer. It is not necessary to add Si. This decrease in the ability to form amorphous can be compensated for by other components described below, in particular C.
[0013]
The contents of B, P and C were limited because they were made amorphous and the melting point was 1100 ° C. or lower.
When B is less than 6 atomic%, it is difficult to form an amorphous state. If it exceeds 14 atomic%, not only the effect of lowering the melting point is lost, but also a boride is formed at the joint and the joint strength is lowered. Therefore, the B content is set to 6 atom% or more and 14 atom% or less.
[0014]
P shows a good low melting point effect in the range of 1 to 20 atomic%. If it is less than 1 atomic%, this effect cannot be obtained, and if it exceeds 20 atomic%, a further effect of addition cannot be obtained and it becomes difficult to form a good foil. Therefore, the P content is set to 1 atom% or more and 20 atom% or less.
[0015]
C is an element that plays an important role in the present invention. That is, the decrease in amorphous forming ability due to the reduction of Si is mainly replaced by C. Therefore, 2 atomic% or more is added. The content is sufficient up to 6 atomic%, and even if the content exceeds 6 atomic%, no further effect of addition can be obtained. C is an element effective in the castability of the ribbon. That is, the wettability between the molten alloy and the cooling substrate is improved within the above range, the cooling rate is increased, and good amorphization can be achieved. Therefore, the C content is set to 2 atom% or more and 6 atom% or less.
[0016]
Ni mainly has an effect of lowering the melting point and is added as necessary. If it is less than 0.1 atomic%, the effect is insufficient, and if it exceeds 20 atomic%, this effect cannot be obtained. Therefore, the Ni content is set to 0.1 atomic% or more and 20 atomic% or less.
[0017]
Cr is added as necessary mainly in order to improve corrosion resistance and oxidation resistance. If it is less than 0.1 atomic%, the effect is insufficient, and if it exceeds 20 atomic%, the melting point exceeds 1100 ° C. Therefore, the Cr content is set to 0.1 atomic% or more and 20 atomic% or less.
[0018]
V has the effect of making the oxide film forming material on the surface to be bonded a low melting point material. For example, there is an effect that Fe ₂ O ₃ is converted to a low melting point composite oxide V ₂ O ₅ —Fe ₂ O ₃ having a melting point of about 800 ° C. When the alloy of the present invention is used, an oxide film is formed at a junction temperature of 900 to 1100 ° C. Melts. Since it is spheroidized in the liquid phase due to the difference in surface tension, diffusing elements such as B, Si, and P diffuse freely, and liquid phase diffusion bonding can be achieved even in an oxidizing atmosphere. If the V content is less than 0.1 atomic%, this effect is insufficient, and if it exceeds 10 atomic%, the melting point exceeds 1100 ° C. Therefore, the V content is set to 0.1 atomic% or more and 10 atomic% or less.
By adding V, bonding in an oxidizing atmosphere becomes possible, but the V-added alloy of the present invention is not limited to an oxidizing atmosphere.
[0019]
The balance other than the above elements consists of Fe and inevitable impurities. As an inevitable impurity, there is no particular problem even if Mn, S, etc. are contained up to about 0.2 atomic%.
[0020]
The joining alloy of the present invention can be used not only for liquid phase diffusion joining but also for joining methods called so-called brazing or brazing. Generally, this bonding method is a method in which after the bonding material is melted, the diffusion elements B, Si, P, etc. in the bonding material are solidified and bonded before being diffused into the material to be bonded.
[0021]
The joining alloy of the present invention can be cast into a thin strip by a single roll method or a twin roll method known as a rapid solidification method and used as a foil-like joining material. In addition to foil, the shape can be powder or the like depending on the application. Further, not only amorphous but also crystalline ones can be used depending on applications.
[0022]
【Example】
About each alloy shown in Table 1, foil was cast on the following conditions by the single roll method. Table 2 shows the melting point and the result of the joining experiment. Each alloy contains 0.2 atomic% of impurities such as Mn and S. The molten alloy temperature at the time of casting was set to a temperature approximately 150 ° C. higher than the melting point shown in Table 2.

[0023]
The melting point of each alloy was determined by a DTA apparatus. As shown in Table 2, all of the inventive examples were 1100 ° C. or lower, but most of the comparative examples exceeded 1100 ° C.
[0024]
As a result of casting, No. of the comparative example. 33, no. 34, No. 41, No. 4 No good foil was obtained for 47, and subsequent joining experiments could not be performed. Other than that, the present invention example and the comparative example could be cast without any problem, and a good foil having a thickness of about 25 μm was obtained.
[0025]
A joining experiment was performed using the obtained foil, and the joining strength was measured after joining. In the joining experiment, two foils each having a disk shape with a diameter of 20 mm were overlapped to form a joining material, and STK400 round steel with a diameter of 20 mm was used as a joining material. As shown in FIG. 1, a bonding material 2 is sandwiched between two bonded materials 1 and bonded. The joining temperature was set in the range of just above the melting point of each alloy to the melting point + 50 ° C., and each atmosphere shown in Table 2 was heated using a heating furnace capable of controlling the atmosphere. During heating, a pressure of 2 MPa was applied in order to improve the adhesion between the material to be bonded 1 and the bonding material 2. The joining time was all 10 minutes.
[0026]
Then, as shown in FIG. 2, a JISA No. 2 tensile test piece 5 was cut out from the round steel 3 after joining around the joining line 4, and a tensile test was performed using a JISA No. 2 tensile tester. In addition, the same test piece was cut out from the base material of the material 2 to be joined before the joining experiment, and the tensile test was performed in the same manner. Indicated.
[0027]
In all of the inventive examples, a high bonding strength exceeding 1.0 in terms of the base material ratio was obtained. This is because the formation of SiO ₂ was suppressed by using a bonding alloy with a reduced Si content as the bonding material, and the bonding temperature could be lowered by using a low melting point alloy as the bonding material. This is considered to be because the strength deterioration of the affected part could be suppressed.
[0028]
On the other hand, all the comparative examples had a base material ratio of 0.91 or less, and a satisfactory bonding strength was not obtained. This is presumably because SiO ₂ was generated in the joint and the melting point of the joining material was high, so that the joining temperature had to be increased, and the strength of the heat-affected zone deteriorated accordingly.
[0029]
[Table 1]

[0030]
[Table 2]

[0031]
【The invention's effect】
The low melting point bonding alloy of the present invention has improved the material of the bonding layer by reducing the Si content, and the component composition has been optimized to achieve a melting point of 1100 ° C. or lower, enabling bonding at a lower temperature. For this reason, the high joint strength exceeding 1.0 with respect to base material ratio is obtained stably. Therefore, it is possible to perform bonding without impairing the properties of the materials to be bonded, and it is possible to reduce the bonding cost by lowering the heating temperature.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram of a joining experiment in an example.
FIG. 2 is an explanatory view of a tensile test piece in an example.
[Explanation of symbols]
1: Joined material 2: Joined material 3: Round steel after joining 4: Joining wire 5: Tensile test piece

Claims

Atomic%
B: 6% or more and 14% or less, Si: less than 2%,
C: 2% or more and 6% or less, P: 1% or more and 20% or less, the balance consisting of Fe and inevitable impurities, being amorphous and having a melting point of 1100 ° C. or less at the same time An iron-based low melting point alloy.

Atomic%
B: 6% or more and 14% or less, Si: less than 2%,
C: 2% or more and 6% or less, P: 1% or more and 20% or less, Ni: 0.1% or more and 20% or less, with the balance being Fe and inevitable impurities, amorphous and melting point 1100 ° C. An iron-based low-melting-point alloy that satisfies the following requirements at the same time:

Atomic%
B: 6% or more and 14% or less, Si: less than 2%,
C: 2% to 6%, P: 1% to 20%,
Iron: low melting point characterized by containing Cr: 0.1% or more and 20% or less, the balance being Fe and inevitable impurities, being amorphous and having a melting point of 1100 ° C. or less at the same time Alloy for bonding.

Atomic%
B: 6% or more and 14% or less, Si: less than 2%,
C: 2% to 6%, P: 1% to 20%,
V: Fe-based low melting point characterized by containing 0.1% to 10%, the balance being Fe and inevitable impurities, being amorphous and having a melting point of 1100 ° C. or less at the same time Alloy for bonding.

Atomic%
B: 6% or more and 14% or less, Si: less than 2%,
C: 2% to 6%, P: 1% to 20%,
Ni: 0.1% or more and 20% or less, Cr: containing 0.1% or more and 20% or less, the balance being Fe and unavoidable impurities, at the same time that amorphous and and a melting point of 1100 ° C. or less An iron-based low-melting point alloy characterized by satisfaction .

Atomic%
B: 6% or more and 14% or less, Si: less than 2%,
C: 2% to 6%, P: 1% to 20%,
Ni: 0.1% or more and 20% or less, V: containing 0.1% to 10% or less, the balance being Fe and unavoidable impurities, at the same time that amorphous and and a melting point of 1100 ° C. or less An iron-based low-melting point alloy characterized by satisfaction .

Atomic%
B: 6% or more and 14% or less, Si: less than 2%,
C: 2% to 6%, P: 1% to 20%,
Cr: 0.1% or more and 20% or less, V: containing 0.1% to 10% or less, the balance being Fe and unavoidable impurities, at the same time that amorphous and and a melting point of 1100 ° C. or less An iron-based low-melting point alloy characterized by satisfaction .

Atomic%
B: 6% or more and 14% or less, Si: less than 2%,
C: 2% to 6%, P: 1% to 20%, Ni: 0.1% to 20%, Cr: 0.1% to 20%,
V: Fe-based low melting point containing 0.1% or more and 10% or less, the balance consisting of Fe and inevitable impurities, being amorphous and having a melting point of 1100 ° C. or less at the same time Alloy for bonding.