JP2004001064A

JP2004001064A - Ferrous alloy for low melting point bonding

Info

Publication number: JP2004001064A
Application number: JP2002259276A
Authority: JP
Inventors: Yuichi Sato; 佐藤　有一; Hiroaki Sakamoto; 坂本　広明
Original assignee: Nippon Steel Corp
Current assignee: Nippon Steel Corp
Priority date: 2002-04-15
Filing date: 2002-09-04
Publication date: 2004-01-08
Anticipated expiration: 2022-09-04
Also published as: JP3822850B2

Abstract

<P>PROBLEM TO BE SOLVED: To provide an alloy for low melting point bonding to enable the bonding at a lower temperature and improve the bonding strength by optimizing the alloy composition of a bonding material. <P>SOLUTION: This alloy has a composition consisting of, by atom %, 6-14% B, 2-3.5% Si, 0.2-4% C, and 1-20% P, and the balance Fe with inevitable impurities, with the melting point thereof being ≤1,100°C. The alloy further contains at least one kind of 0.1-20% Ni, 0.1-20% Cr, and 0.1-10% V. Since the melting point is ≤1,100°C, the bonding at a lower temperature is possible, and the bonding strength exceeding 0.9 compared with a base metal is consistently obtained. Thus, the bonding does not impair any characteristic of a work to be bonded. In addition, a bonding cost is reduced by dropping a heating temperature. <P>COPYRIGHT: (C)2004,JPO

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。かかる要望を充足するために、本発明者らは実験検討を行った結果、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分かった。
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、より低温での接合を可能とし、接合強度を向上できる低融点接合用合金を提供することである。
【０００７】
【課題を解決するための手段】
上記課題を解決するための本発明は、原子％にて、Ｂ：６％以上１４％以下、Ｓｉ：２％以上３．５％以下、Ｃ：０．２％以上４％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、融点が１１００℃以下であることを特徴とする鉄系低融点接合用合金である。
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、融点が１１００℃以下であることを特徴とする鉄系低融点接合用合金である。
【０００８】
【発明の実施の形態】
本発明の接合用合金は、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、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。
以下に成分の限定理由を述べる。
【０００９】
Ｂ、Ｓｉ、Ｐ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％超となると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。
【００１０】
Ｓｉは、２原子％未満および３．５原子％超では低融点化効果がなくなり、また非晶質形成が困難となる。したがってＳｉ含有量を２原子％以上３．５原子％以下とした。
【００１１】
Ｐは、本発明で最も重要な元素であり、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。
【００１２】
Ｃは、薄帯の鋳造性に効果のある元素である。すなわち、０．２原子％以上４原子％以下の添加により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。０．２原子％未満ではこの効果は得られず、４原子％超としてもさらなる添加効果は得られない。したがってＣ含有量を０．２原子％以上４原子％以下とした。
【００１３】
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。
【００１４】
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。
【００１５】
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Ｆｅ_２Ｏ_３を、融点が約８００℃の低融点複合酸化物Ｖ_２Ｏ_５−Ｆｅ_２Ｏ_３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。
【００１６】
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。
【００１７】
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。
【００１８】
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。
【００１９】
【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。

【００２０】
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、比較例はいずれも１１００℃を超えるものであった。
鋳造結果、比較例のＮｏ．３４、Ｎｏ．３５、Ｎｏ．４２、Ｎｏ．４７、Ｎｏ．４８、Ｎｏ．４９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。
【００２１】
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。
【００２２】
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。
【００２３】
本発明例は、いずれも対母材比で０．９を超える高い接合強度が得られた。これは、融点の低い本発明合金からなる接合材を使用したことで、接合温度を低くすることができ、そのため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。
【００２４】
これに対して、比較例はいずれも対母材比で０．９未満であり、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。
【００２５】
【表１】

【００２６】
【表２】

【００２７】
【発明の効果】
本発明の低融点接合用合金は、成分組成を最適化して融点を１１００℃以下としたことにより、より低温での接合が可能となり、対母材比で０．９を超える高い接合強度が安定して得られる。このため、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]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a joining alloy for joining iron-based materials such as various structures.
[0002]
[Prior art]
BACKGROUND ART In joining iron-based materials such as various structures, a liquid phase diffusion joining method is known. Liquid phase diffusion bonding is a method in which a bonding material having a lower melting point than the material to be bonded is interposed between the materials to be bonded and heated just above the liquidus line to diffuse the diffusion elements in the bonding material and perform bonding. .
[0003]
The present inventors have invented a liquid phase diffusion bonding alloy foil of an iron-based material that can realize liquid phase diffusion bonding in an oxidizing atmosphere, and have applied for a patent (see Patent Document 1).
The alloy foil contains P: 1.0 to 20.0 atomic%, Si: 1.0 to 10.0 atomic%, V: 0.1 to 20.0 atomic%, B: 1.0 to 20.0 atomic%. Atomic%, further contains Cr, Ni, Co, W, Nb, and Ti as necessary, and the balance has a composition consisting of Fe and unavoidable impurities, and has a thickness of 3.0 to 200 μm. It is foil.
[0004]
[Patent Document 1]
JP-A-9-323175
Further, as a method for manufacturing such an alloy foil, a single roll method, a twin roll method, and the like are known. In these methods, a molten metal is ejected from an orifice or the like on an outer peripheral surface of a metal drum rotating at a high speed to rapidly solidify the molten metal, thereby casting a ribbon. By properly 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 joining disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 9-323175, improvement in joining strength has been required. In order to satisfy such a demand, the present inventors have conducted experimental studies and found that it is effective to lower the heating temperature during joining by lowering the melting point of the joining material.
Accordingly, an object of the present invention is to provide a low-melting point joining alloy that enables joining at lower temperatures and improves joining strength by optimizing the alloy composition of the joining material.
[0007]
[Means for Solving the Problems]
According to the present invention for solving the above problems, in atomic%, B: 6% to 14%, Si: 2% to 3.5%, C: 0.2% to 4%, P: 1 % Of Fe and 20% or less, the balance being Fe and unavoidable impurities, and having a melting point of 1100 ° C. or less.
Further, the present invention further provides at least one of Ni: 0.1% to 20%, Cr: 0.1% to 20%, and V: 0.1% to 10% in atomic%. And a balance consisting of Fe and unavoidable impurities and having a melting point of 1100 ° C. or less.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
The composition of the joining alloy of the present invention is limited from the viewpoint of lowering the melting point. Although the melting point of the alloy is uniquely determined by the composition of the component, it is particularly effective to use the joining alloy of the present invention in the form of an amorphous foil. The composition is limited. Note that the amorphous material does not need to be formed on the entire foil.
The reasons for limiting the components are described below.
[0009]
The contents of B, Si, and P are limited because they realize amorphization and have a melting point of 1100 ° C. or less.
If B is less than 6 atomic%, it becomes difficult to form an amorphous phase. If the content exceeds 14 atomic%, not only the effect of lowering the melting point is lost but also boride is generated at the joint to lower the joint strength. Therefore, the B content is set to 6 at% to 14 at%.
[0010]
If the content of Si is less than 2 at% and more than 3.5 at%, the effect of lowering the melting point is lost, and the formation of amorphous becomes difficult. Therefore, the Si content is set to 2 atomic% or more and 3.5 atomic% or less.
[0011]
P is the most important element in the present invention, and exhibits a good effect of lowering the melting point 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%, not only an additional effect cannot be obtained, but also it becomes difficult to form a good foil. Therefore, the P content is set to 1 atomic% or more and 20 atomic% or less.
[0012]
C is an element effective for the castability of the ribbon. That is, by adding 0.2 atomic% or more and 4 atomic% or less, the wettability between the molten alloy and the cooling substrate is improved, the cooling rate is increased, and good amorphousness can be achieved. If it is less than 0.2 atomic%, this effect cannot be obtained, and even if it exceeds 4 atomic%, no additional effect can be obtained. Therefore, the C content is set to 0.2 atomic% or more and 4 atomic% or less.
[0013]
Ni mainly has a melting point lowering effect, 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.
[0014]
Cr is added as needed, mainly to increase corrosion resistance and oxidation resistance. If the content is less than 0.1 at%, the effect is insufficient, and if it exceeds 20 at%, the melting point exceeds 1100 ° C. Therefore, the Cr content is set to 0.1 atomic% or more and 20 atomic% or less.
[0015]
V has the effect of making the oxide film forming substance on the surface to be joined a low melting point substance. For example, there is an effect that Fe ₂ O ₃ is converted into 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 joining temperature of 900 to 1100 ° C. Melts. In the liquid phase, spheres are formed by the difference in surface tension, so that diffusion 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.
[0016]
The balance other than the above elements consists of Fe and inevitable impurities. There is no particular problem even if Mn, S, etc. are contained up to about 0.2 atomic% as inevitable impurities.
[0017]
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. In general, this joining method is a method of solidifying and joining before the diffusion elements B, Si, P and the like in the joining material are diffused into the joined material after the joining material is melted.
[0018]
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 a foil shape, a powder or the like can be used depending on the application. Further, not only amorphous but also crystalline ones can be used depending on the application.
[0019]
【Example】
For each alloy shown in Table 1, a foil was cast by the single roll method under the following conditions. Table 2 shows the melting points and the results of the joining experiments. Each alloy contains 0.2 at% of impurities such as Mn and S. The temperature of the molten alloy at the time of casting was set to a temperature approximately 150 ° C. higher than the melting point shown in Table 2.

[0020]
The melting point of each alloy was determined using a DTA device. As shown in Table 2, all of the examples of the present invention were lower than 1100 ° C., but all of the comparative examples exceeded 1100 ° C.
The casting results and the comparative example Nos. 34, no. 35, no. 42, no. 47, no. 48, no. In No. 49, a good foil was not obtained, and a subsequent bonding experiment could not be performed. Other than that, both the present invention example and the comparative example could be cast without any problem, and a good foil having a plate thickness of about 25 μm was obtained.
[0021]
A joining experiment was performed using the obtained foil, and the joining strength was measured after joining. At the time of the joining experiment, two disc-shaped foils each having a diameter of 20 mm were overlapped to form a joining material, and a round steel of STK400 having a diameter of 20 mm was used as a joining material. As shown in FIG. 1, a joining material 2 was sandwiched between two joining materials 1 and joined. The bonding temperature was set in a range from the temperature immediately above the melting point of each alloy to the melting point + 50 ° C., and heating was performed in each atmosphere shown in Table 2 using a heating furnace capable of controlling the atmosphere. During the heating, pressure was applied at 2 MPa to enhance the adhesion between the material 1 to be joined and the joining material 2. All joining times were 10 minutes.
[0022]
Then, as shown in FIG. 2, a JISA No. 2 tensile test piece 5 was cut out from the round bar 3 after the bonding centering on the bonding 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 a tensile test was performed in the same manner, and the joining strength was shown in Table 2 as a ratio of the base material (joint strength) / (base material strength). Indicated.
[0023]
In all of the examples of the present invention, a high bonding strength exceeding 0.9 in the ratio of the base material was obtained. This is presumably because the use of the bonding material made of the alloy of the present invention having a low melting point enabled the bonding temperature to be lowered, thereby suppressing the deterioration of the strength of the heat-affected zone of the bonding portion.
[0024]
On the other hand, in all of the comparative examples, the ratio of the base material to the base material was less than 0.9, and satisfactory joining strength was not obtained. This is considered to be because 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.
[0025]
[Table 1]

[0026]
[Table 2]

[0027]
【The invention's effect】
The low melting point bonding alloy of the present invention can be bonded at a lower temperature by optimizing the composition of the components to a melting point of 1100 ° C. or less, and has a stable bonding strength of more than 0.9 in a base metal ratio. Is obtained. For this reason, it is possible to perform joining without impairing the properties of the materials to be joined, and it is also possible to reduce the joining 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: Material to be joined 2: Joint material 3: Round steel after joining 4: Joining wire 5: Tensile test piece

Claims

In atomic%,
B: 6% or more and 14% or less, Si: 2% or more and 3.5% or less,
Iron-based low-melting point joining containing C: 0.2% or more and 4% or less, P: 1% or more and 20% or less, the balance being Fe and unavoidable impurities, and having a melting point of 1100 ° C. or less. For alloys.

In atomic%,
B: 6% or more and 14% or less, Si: 2% or more and 3.5% or less,
C: 0.2% to 4%, P: 1% to 20%,
Ni: an iron-based low melting point joining alloy containing 0.1% or more and 20% or less, with the balance being Fe and inevitable impurities and having a melting point of 1100 ° C or less.

In atomic%,
B: 6% or more and 14% or less, Si: 2% or more and 3.5% or less,
C: 0.2% to 4%, P: 1% to 20%,
Cr: an iron-based low melting point bonding alloy containing 0.1% or more and 20% or less, the balance being Fe and unavoidable impurities, and having a melting point of 1100 ° C. or less.

In atomic%,
B: 6% or more and 14% or less, Si: 2% or more and 3.5% or less,
C: 0.2% to 4%, P: 1% to 20%,
V: an iron-based low melting point bonding alloy containing 0.1% or more and 10% or less, with the balance being Fe and inevitable impurities and having a melting point of 1100 ° C. or less.

In atomic%,
B: 6% or more and 14% or less, Si: 2% or more and 3.5% or less,
C: 0.2% to 4%, P: 1% to 20%,
Ni: 0.1% or more and 20% or less, Cr: 0.1% or more and 20% or less, with the balance being Fe and inevitable impurities and having a melting point of 1100 ° C. or less. Alloy for melting point joining.

In atomic%,
B: 6% or more and 14% or less, Si: 2% or more and 3.5% or less,
C: 0.2% to 4%, P: 1% to 20%,
Ni: 0.1% to 20%, V: 0.1% to 10%,
And a balance consisting of Fe and inevitable impurities and having a melting point of 1100 ° C. or less.

In atomic%,
B: 6% or more and 14% or less, Si: 2% or more and 3.5% or less,
C: 0.2% to 4%, P: 1% to 20%,
Fe: 0.1% or more and 20% or less, V: 0.1% or more and 10% or less, with the balance being Fe and unavoidable impurities and having a melting point of 1100 ° C. or less. Alloy for melting point joining.

In atomic%,
B: 6% or more and 14% or less, Si: 2% or more and 3.5% or less,
C: 0.2% to 4%, P: 1% to 20%,
Ni: 0.1% to 20%, Cr: 0.1% to 20%,
V: an iron-based low melting point bonding alloy containing 0.1% or more and 10% or less, with the balance being Fe and inevitable impurities and having a melting point of 1100 ° C. or less.