JP6545143B2 - Heterometallic joining method and heterometallic joining member - Google Patents

Description

  The present invention relates to a dissimilar metal joining method and dissimilar metal joining member in which an aluminum material and a steel material are directly joined without dissimilar metals, filler metals or pretreatment.

In recent years, from the demand for structural members in consideration of global environmental problems, the need for multi-materialization by joining dissimilar metals is increasing.
For example, joining technologies of dissimilar metals are actively researched for weight reduction, improvement of thermoelectric characteristics, improvement of corrosion resistance, selectivity of material strength, etc. mainly in the automobile industry, aerospace industry, precision instrument industry etc. It is done.

  Among the combinations of joining metals required in the future, dissimilar material joining of a steel material of a large amount used and a lightweight aluminum material is in high demand and the most noted. However, for example, in the case of diffusion bonding, it is known that a brittle and hard intermetallic compound (IMC) is generated at the bonding interface between an aluminum material and a steel material, and the joint strength is significantly reduced.

  For example, Non-Patent Document 1 and Patent Documents 1 to 3 disclose a method of joining a steel material and an aluminum material.

  Non-Patent Document 1 discloses various methods as “laser welding of steel material and aluminum alloy”.

  In "The method of joining steel-based material and aluminum material" in Patent Document 1, while inserting a copper-based filler wire, the beam is scanned and integrated using a beam having a high energy density such as an electron beam or a laser beam. It is

  In the "welding method of iron-aluminum material and iron-aluminum joint member" of Patent Document 2, the joint surface of the steel material and the aluminum material is plated, the melting point is lower than that of the aluminum material and the intermetallic compound with the steel material is plated. Using a metal capable of producing

  According to the “joining method of an iron-based member and an aluminum-based member” in Patent Document 3, the steel plate has a zinc-plated layer containing zinc formed on the joining side, and the steel plate and the aluminum plate are overlapped so as to sandwich the zinc-plated layer. And spot welding.

Laser Research Vol. 38 (2010) No. 8 "Laser joining technology of different materials" p. 594-602

JP 2002-283080 A JP, 2009-72812, A International Publication No. 2006/046608

Non-patent document 1 mainly irradiates a steel material with a laser beam, and simultaneously irradiates a part thereof with an Al alloy to heat the steel without melting it and melts only the Al alloy with its heat and a part of the irradiation laser Disclose how to
However, the thickness of the applied plate of this method is limited to about 1.5 mm or less, and the strength of the obtained joint is reduced by about 30% as compared with that of the joint between Al materials. That is, in the butt welding according to this method, there is disclosed a method of simultaneously performing lap welding and butt welding in one pass simultaneously, since sufficient tensile strength can not be obtained and impact strength is low.

In the joining method of Patent Document 1, it is necessary to insert a filler material (filler wire).
In the bonding method of Patent Document 2, it is necessary to plate the bonding surface.
The bonding method of Patent Document 3 needs to form a zinc layer containing zinc on the bonding side.

  The present invention has been made to solve the above-mentioned problems. That is, the object of the present invention is that there is no need for pretreatment such as different materials such as clad material, filler materials such as filler wire, plating, formation of zinc layer, etc., and direct bonding of aluminum material of 2 mm thickness or more and steel material It is an object of the present invention to provide a dissimilar metal bonding method and a dissimilar metal bonding member that can achieve high tensile strength.

According to the present invention, the bonding surfaces of the aluminum material and the steel material are brought into direct contact with each other,
In vacuum, the bonding surface is offset from the bonding surface to the aluminum material side, and an electron beam is irradiated parallel to the bonding surface to dissolve only the aluminum material, and the layer thickness is 0.5 to 2.0 μm at the welded bonding interface A method of dissimilar metal bonding is provided, which produces an intermetallic compound of

Further, according to the present invention, the joint surface where the aluminum material and the steel material are in close contact with each other
An aluminum melting portion which is offset from the bonding surface to the aluminum material side and in which only the aluminum material is melted and welded along the bonding surface by electron beam welding;
There is provided a dissimilar metal joining member having an intermetallic compound having a layer thickness of 0.5 to 2.0 μm generated on the joining surface side of the aluminum melting portion.

  According to the present invention, only the aluminum material is melted in vacuum by irradiating an electron beam offset from the bonding surface to the aluminum material side and parallel to the bonding surface. Thereby, an aluminum material and a steel material can be welded, and an intermetallic compound can be generated at the welded interface.

  Also, electron beam welding is processing in a vacuum chamber, energy density is very high, and local irradiation is possible, so different materials such as clad material, filler metals such as filler wire, plating, formation of zinc layer, etc. It is not necessary to pre-treat, and aluminum and steel materials can be directly joined with a thickness of 2 mm or more.

  Furthermore, since electron beam welding has high beam controllability for electromagnetic control, high tensile strength can be achieved by forming an intermetallic compound having a layer thickness of 0.5 to 2.0 μm at the welded joint interface. It is confirmed by the examples that it can be obtained.

It is a schematic diagram which shows 1st Embodiment of the dissimilar-metal joining method by this invention. It is a schematic diagram which shows 2nd Embodiment of the dissimilar metal joining method by this invention. It is a typical sectional view of a dissimilar-metal joining member by the present invention. It is an Al-Fe system equilibrium state figure. It is a related figure of the layer thickness of an intermetallic compound (IMC), and tensile strength. FIG. 7 is a test flow chart in Example 2. 7 is a temperature profile of a heat cycle test in Example 2. It is a schematic diagram which shows the welding method of a test piece. FIG. 10 is a test flow chart in Example 3.

  Hereinafter, embodiments of the present invention will be described based on the drawings. In addition, the same code | symbol is attached | subjected to the part which is common in each figure, and the duplicate description is abbreviate | omitted.

  FIG. 1 is a schematic view showing a first embodiment of the dissimilar metal bonding method according to the present invention.

  As shown in this example, the method of the present invention is a dissimilar metal bonding method in which the aluminum material 1 and the steel material 2 are directly bonded. First, the bonding surfaces 4 and 5 of the aluminum material 1 and the steel material 2 are directly adhered Let

The aluminum material 1 is a pure aluminum material or an aluminum alloy material containing aluminum as a main component. Hereinafter, the aluminum material 1 is simply referred to as “Al material 1” except when necessary.
The steel material 2 is a steel material containing 0.3% to 2% of carbon, or a stainless steel material. Hereinafter, the steel material 2 is simply referred to as "Fe material 2" except when necessary.

In this example, the Al material 1 and the Fe material 2 are flat plates, and the bonding surfaces 4 and 5 are end surfaces perpendicular to the surface.
"Direct contact" means that the bonding surfaces 4 and 5 are in close contact with each other without gaps, and different materials such as clad materials and filler metals such as filler wire are not used, and pretreatments such as plating and formation of a zinc layer Means not to carry out. In order to maintain the state of direct adhesion, it is preferable to fix the Al material 1 and the Fe material 2 respectively. Also, in order to maintain this state, one of the Al material 1 and the Fe material 2 may be biased toward the other.

  The method of the present invention is then irradiated with the electron beam 10 offset in a vacuum from the bonding surfaces 4 and 5 to the aluminum material side and parallel to the bonding surfaces 4 and 5 to melt and weld only the Al material 1 Intermetallic compound 12 (IMC) having a thickness of 0.5 to 2.0 μm is formed at bonding interface F.

Electron beam welding applied in the present invention is processing in a vacuum chamber, has a very high energy density, can be locally irradiated, and has high beam controllability because of electromagnetic control.
Therefore, compared to arc welding, plasma welding, and laser welding, no filler metal is required, the spot diameter is very small, and the penetration is deep with a narrow beam width.

  It is preferable that offset amount e from the joint surfaces 4 and 5 is 0.50-1.25 mm from the Example mentioned later.

  Preferably, the atomic composition percentage of aluminum of the intermetallic compound 12 is 70 to 87%, and the ratio Al / Fe of the atomic composition percentage of aluminum to iron of the intermetallic compound 12 is 3.1 to 8.2. .

Furthermore, the intermetallic compound 12 is preferably a metastable intermetallic compound containing Fe ₂ Al ₉ or FeAl ₆ .

  The intensity or irradiation time of the electron beam 10 is controlled to generate the intermetallic compound 12 described above.

  FIG. 2 is a schematic view showing a second embodiment of the dissimilar metal bonding method according to the present invention.

In this example, the Al material 1 and the Fe material 2 are circular tubes, and their joint surfaces 4 and 5 are end surfaces perpendicular to the surface.
The other configuration is the same as that of the first embodiment.

  FIG. 3 is a schematic cross-sectional view of a dissimilar metal joining member 14 according to the present invention.

  In this figure, the dissimilar metal joining member 14 according to the present invention is a dissimilar metal joining member in which an Al material 1 and an Fe material 2 are directly joined, and has joining surfaces 4 and 5, an aluminum melting portion 16 and an intermetallic compound 12. .

In the bonding surfaces 4 and 5, the Al material 1 and the Fe material 2 are in direct contact with each other.
The aluminum melting portion 16 is a portion offset from the bonding surfaces 4 and 5 to the aluminum material side, and melted and welded only the Al material 1 along the bonding surfaces 4 and 5 by electron beam welding.
The intermetallic compound 12 is formed on the bonding surface side of the aluminum melting portion 16 and has a layer thickness of 0.5 to 2.0 μm as described above.

The penetration width B from the joint surfaces 4 and 5 of the aluminum melting portion 16 is preferably 2 to 3 times the offset amount e.
The penetration depth H of the aluminum melting portion 16 is, for example, not less than 5 times and not more than 20 times the offset amount e.

  Hereinafter, examples of the present invention will be described.

  As shown in FIG. 1, Al material 1 and Fe material 2 which are flat plates of the same thickness were prepared, and their joint surfaces 4 and 5 were joined by the method of the first embodiment.

  Table 1 shows the type and thickness of each material used.

  As shown in FIG. 1, the bonding surfaces 4 and 5 of the Al material 1 and the Fe material 2 are butted and installed. At this time, the bonding surfaces 4 and 5 are fixed so as not to open at the time of bonding. Taking the butt joint interface F (joint surfaces 4 and 5) of the Al material 1 and the Fe material 2 as a reference line, offset the irradiation position 3 to the aluminum side by a predetermined width, electron beam 10 parallel to the joint interface F Irradiate to dissolve only the Al material 1. At this time, scanning is performed without dissolving the Fe material 2.

The welding conditions in this case are selected such that the required penetration depth H can be obtained, and only the Al material 1 can be melted at the predetermined irradiation position 3 to perform joining without melting the Fe material 2.
The penetration depth H at the time of welding may be selected from the conditions in which the plate thickness is penetrated and butt penetration welding is performed, and the penetration depth H is equal to or less than the plate thickness.

  Table 2 shows the welding conditions used in this example. Note that this welding condition is an example, and may be different as long as the desired intermetallic compound 12 can be generated at the welded joint interface F.

Table 3 shows the relationship between the offset amount e, the appearance after welding, and the cross-sectional observation.
The offset amount e is an offset amount from the bonding interface F, and corresponds to the irradiation position 3 of the electron beam 10 to the Al material 1.
The appearance after welding is the presence or absence of defects such as cracks or pinholes on the surface of the weld bead. Cross-sectional observation is the presence or absence of a cross-sectional defect when cut in a direction perpendicular to the weld bead and observed with an optical microscope. Cross-sectional observation was cut with a micro cutting machine and observed with an optical microscope.
In the table, the symbol ○ indicates that there is no crack or defect, the symbol Δ indicates that there is a slight defect, and the symbol x indicates that there is a crack, defect or poor fusion.

From Table 3, when offset amount e was 0 mm and 0.25 mm, a crack or a fracture was confirmed immediately after welding, and it became clear that joining was impossible.
When the offset amount e is 1.25 mm or more, large porosity and the like are confirmed in the vicinity of the bonding interface F, and it is confirmed that the bonding property is lowered.
From the above, when this welding condition is used, it has been confirmed that the appropriate offset amount e is preferably 0.50 mm to 1.25 mm, and more preferably 0.60 mm to 0.90 mm.

Table 4 shows the elemental analysis, the intermetallic compound 12, the tensile strength, and the base material strength ratio of the sample having the offset amount e of 0.50 mm to 1.00 mm.
Elemental analysis is based on EDS analysis (energy dispersive X-ray analysis) of the intermetallic compound 12. The layer thickness of the intermetallic compound 12 is based on the SEM image. The compound species of the intermetallic compound 12 is an Al—Fe-based intermetallic compound identified by elemental analysis. The base material strength ratio is a ratio of pure aluminum (A1050 material) having a purity of 99.5% or more to the base material strength (95 N / mm ² ).

In Table 4, when the offset amount e is 0.60, 0.75, 1.00 mm, a metastable phase of Fe ₂ Al ₉ is identified as a compound species of the intermetallic compound 12. In addition, when the offset amount e was 0.90 mm, a metastable phase of FeAl ₆ was identified as a compound species of the intermetallic compound 12.
Accordingly, when the offset amount e is 0.60 to 0.90 mm, the intermetallic compound 12 can be said to be a metastable intermetallic compound containing Fe ₂ Al ₉ or FeAl ₆ . Moreover, when offset amount e is 0.60-1.00 mm, it was confirmed that high tensile strength over 77% is obtained by base material strength ratio.

  FIG. 4 is an Al-Fe-based equilibrium phase diagram, and Table 5 shows compound species of known intermetallic compounds 12 of Al-Fe-based two elements.

Two metastable intermetallic compounds of Fe ₂ Al ₉ and FeAl ₆ in FIGS. It is a phase discovered by J Richmond et al., And is a phase that precipitates from an aluminum-rich Al solution during moderate quenching.
The electron beam welding in the present invention is performed in vacuum as described above, and has features such as very small spot diameter, very high energy density, and deep penetration to the beam width. Therefore, the electron beam welding in the present invention is an endothermic process in which a high energy density heat source is locally irradiated, and is cooled rapidly after irradiation, and thus corresponds to the above-mentioned appropriate quenching, Fe ₂ Al ₉ Alternatively, it is considered that a metastable phase consisting of FeAl ₆ is formed.

The offset amount e in Table 4 is the case of 0.50 mm, a compound species of the intermetallic compound 12, _Fe 2 stable phases of Al ₅ (Stable) have been identified, base material strength ratio was 66% .
The base material strength ratio is lower than in the case where the offset amount e is 0.60 to 0.90 mm, it is considered that a brittle and hard equilibrium type intermetallic compound phase (Fe ₂ Al ₅ ) is formed.

In addition, when the offset amount e is 1.00 mm, the stable phase of Fe ₂ Al ₅ is identified as the compound species of the intermetallic compound 12, but the base material strength ratio is 77%.
The lower base material strength ratio than in the case of the offset amount e of 0.60 to 0.90 mm may be an increase in defects (such as porosity) in the vicinity of the bonding interface F.
Further, when the offset amount e is 1.25 mm, it is estimated from Table 3 and Table 4 that a base material strength ratio close to the case where the offset amount e is 1.00 mm can be obtained.

From the above, it can be said that the appropriate offset amount e is preferably 0.50 to 1.25 mm, and more preferably 0.60 to 1.00 mm.
When offset amount e is 0.60 mm to 1.00 mm, intermetallic compound 12 having a layer thickness of 1.2 to 1.5 μm is formed at welded joint interface F, and high tensile strength exceeding 77% in base material strength ratio It was confirmed that the strength could be obtained.
Still more preferably, the appropriate offset amount e is 0.60 mm to 0.90 mm, and in this case, the intermetallic compound 12 is a metastable intermetallic compound containing Fe ₂ Al ₉ or FeAl ₆ , and It was confirmed that high tensile strength exceeding 95% can be obtained in material strength ratio.
From Table 4, when the offset amount e is from 0.50 mm to 1.00 mm, the atomic composition percentage of aluminum of the intermetallic compound 12 is 70 to 87%, and the ratio of the atomic composition percentage of aluminum to iron of the intermetallic compound 12 Al / Fe was 3.1 to 8.2.
In addition, when the offset amount e is 0.60 mm to 1.00 mm, according to Table 4, the atomic composition percentage of aluminum of the intermetallic compound 12 is 80 to 87%, and the atomic composition percentage of aluminum and iron of the intermetallic compound 12 The ratio of Al / Fe was 5.3 to 8.2.

FIG. 5 is a diagram showing the relationship between the layer thickness of the intermetallic compound 12 (IMC) and the tensile strength. In this figure, the numerical values in the figure indicate the offset amount e.
From this figure, when the offset amount e is 0.60 mm to 1.00 mm and the layer thickness of the intermetallic compound 12 (IMC) is 1.1 to 1.6 μm, the tensile strength is an offset amount of 0.60 mm. It was confirmed that it could be regarded as a quadratic curve with e at the top.

The same test was also carried out on A5052 (tensile strength 215 N / mm ² ) and A 6061 (tensile strength 215 N / mm ² ), which are aluminum alloys different in tensile strength from the A1050 material.
As a result, in the three types of Al materials 1, the layer thickness of the intermetallic compound 12 was 0.5 to 2.0 μm, and it was confirmed that high tensile strength was obtained.

  As shown in FIG. 2, the Al material 1 and the Fe material 2 which are circular tubes of the same outer diameter were prepared, and the joint surfaces 4 and 5 were joined by the method of the second embodiment.

  Table 6 shows the type and shape of each material used.

  6 is a test flow diagram in Example 2, and FIG. 7 is a temperature profile of a heat cycle test in Example 2.

  In Example 2, the joint shape was a butt pipe joint shape, and a He leak test (S3, S5), a heat cycle test (S6), and a tensile test (S7) were performed.

  As shown in FIG. 2, after the bonding portion is washed in the washing (S1), bonding surfaces 4 and 5 of the Al material 1 and the Fe material 2 are butted and installed. In order to prevent misalignment of the bonding surfaces 4 and 5 of the respective materials, a 1 mm convex process was performed on the inner end surface of the Al material 1 and a 1 mm concave process was performed on the inner end surface of the Fe material 2.

  Next, the inlays of the Al material 1 and the Fe material 2 are fitted and coaxially connected, and fixed by biasing one of the Al material 1 and the Fe material 2 toward the other with a bolt and a nut passing through the central hole .

  Next, in the welding (S2), the Al material side was chucked, and the Al material 1 and the Fe material 2 were rotated about the axial center, and electron beam welding was performed in vacuum. In this electron beam welding, the offset amount e is set to 0.75 mm, the joining interface F where the Al material 1 and the Fe material 2 are butted is used as a reference line, and is offset from the joining surfaces 4 and 5 to the aluminum material side The electron beam 10 was irradiated in parallel to 4, 5. By this irradiation, only the Al material 1 was dissolved, and an intermetallic compound 12 having a layer thickness of 0.5 to 2.0 μm was formed at the welded joint interface F.

After welding, a He leak test (S3) was performed. In the He leak test, a leak rate of 1.0 × 10 ⁻¹⁰ Pa · m ³ / s or less was accepted.
Next, in the secondary processing (S4), the outer diameter 1 mm and the inner diameter 2 mm were cut to confirm the surface defect.
Then, in the heat cycle test (S5), according to the temperature profile of FIG. 7, after keeping the substance temperature 150 ° C. for 1 hour in the electric furnace, the heat cycle test of quenching by injecting into tap water of 26 ± 2 ° C. The heat cycle test was performed repeatedly.

The He leak test after the heat cycle test was conducted at the end of each heat cycle.
The tensile test (S7) is performed on two types, one subjected only to bonding (Experiment No. 10) and one subjected to all heat cycle tests (Experiment No. 11), and strength comparisons before and after the heat cycle test are conducted. The
The test pieces for the tensile test were cut into strips in the direction perpendicular to the bonding surfaces 4 and 5.

  Table 7 is the experiment No. It is the heat cycle test result in each process of joining propriety of each member of 10-12.

  From Table 7, the airtightness by the heat cycle test was maintained in any case, and the joining defect etc. in appearance and a cutting surface were not seen.

Table 8 is the experiment No. 10 and Experiment No. 11 tensile strength and base material strength ratio. The base material strength of the pure aluminum pipe (A1050P) was 84 N / mm ² .

  From Table 8, it was confirmed that the tensile test results show no change before and after the heat cycle test (six cycles), and a high tensile strength of 86% can be obtained in the base material strength ratio.

A heat cycle test was carried out after full circumference (four sides) welding with a square test piece.
FIG. 8 is a schematic view showing a test piece welding method. In this figure, (A) is a front view of a test piece, (B) is a B-B cross-sectional view of (A).
The types of Al material 1 and Fe material 2 are the same as in the first embodiment. Further, the size of each of the Al material 1 and the Fe material 2 was a flat plate of 100 × 50 × t 8, and an exhaust hole (about φ 6) for He leak test was provided at the center of the Al material 1.

FIG. 9 is a test flow diagram in Example 3.
In the washing (T1) of FIG. 9, the butted surfaces of the test piece were washed with acetone, and in welding (T2), the four sides were divided into four parts and welded. The welding conditions were the same as in Example 2.
In the heat cycle test (T4, T7), according to the temperature profile shown in FIG. 7, the sample was kept at 150 ° C. for 1 hour in an electric furnace and then placed in tap water (20 ± 0.5 ° C.) and quenched. .
After repeating the heat cycle test (T4) for 3 cycles, in bead removal (T5), each surface was shaved by 0.5 to 1 mm with a four-faced cutter (4F) to remove the bead. Thereafter, a heat cycle test (T7) of 3 cycles was performed again, and then in the pressure test (T8), air pressure was applied at 0.5 MPa for 18 hours, and no peeling was confirmed.
The conditions for the He leak test (T3, T6, T9) were the same as in Example 2.
The He leak test was performed a total of nine times after welding (T3), after quenching (T4) of each cycle of the heat cycle test, after bead removal (T6) and after pressurization (T9).

  Table 9 shows the test results of the He leak test according to Example 3.

From this table, in the nine He leak tests of Example 3, it was confirmed that there was no leak in any of the steps under the same conditions as Example 2.
Further, from the cross-sectional macro observation thereafter, a joint having a penetration depth H of about 10 mm (effective penetration depth 8 to 9 mm) was confirmed on each surface.

  According to the embodiment of the present invention described above, only the Al material 1 is melted by irradiating the electron beam 10 in parallel to the bonding surfaces 4 and 5 offset from the bonding surfaces 4 and 5 to the aluminum material side in vacuum. . Thereby, the intermetallic compound 12 can be generated at the bonded interface F where the Al material 1 and the Fe material 2 are welded and welded.

  Also, electron beam welding is processing in a vacuum chamber, energy density is very high, and local irradiation is possible, so different materials such as clad material, filler metals such as filler wire, plating, formation of zinc layer, etc. The steel sheet 2 can be directly bonded to the aluminum material 1 having a thickness of 2 mm or more.

  Furthermore, since electron beam welding has high beam controllability for electromagnetic control, high tensile strength can be achieved by forming the intermetallic compound 12 with a layer thickness of 0.5 to 2.0 μm at the welded joint interface F. It was confirmed by the example that strength can be obtained.

As described above, according to the present invention, the high energy density and high controllability of electron beam welding enable selective irradiation, melting, and quenching of the member, and the layer thickness and compound type of the intermetallic compound 12 It is possible to create a controlled joint.
In addition, it is more adaptable to thick plates than conventional methods such as laser welding.

  That is, according to the present invention, it is possible to join dissimilar material joints of Al material 1 and Fe material 2 which have sufficiently high strength and a high degree of freedom in joint shape. In addition, the joint strength does not change with respect to heat history such as heat cycle, and application to a member requiring baking such as a vacuum device is also possible.

  The joining method in the present invention is not limited to butt welding, and may be another joint shape.

  The present invention is not limited to the above-described embodiment, and it goes without saying that various modifications can be made without departing from the scope of the present invention.

B penetration width, e offset amount, F junction interface, H penetration depth,
1 aluminum material (Al material), 2 steel material (Fe material), 3 irradiation position,
4,5 junction surface, 6 irradiation position, 10 electron beam, 12 intermetallic compound (IMC),
14 Dissimilar metal joining member, 16 aluminum melting part

Claims (8)

Direct contact between aluminum material and steel material,
In vacuum, the bonding surface is offset from the bonding surface to the aluminum material side, and an electron beam is irradiated parallel to the bonding surface to dissolve only the aluminum material, and the layer thickness is 0.5 to 2.0 μm at the welded bonding interface A method of joining dissimilar metals to form an intermetallic compound of   The dissimilar metal joining method according to claim 1, wherein the offset amount from the joining surface is 0.50 to 1.25 mm. The atomic composition percentage of aluminum of the intermetallic compound is 70 to 87%,
The method for bonding dissimilar metals according to claim 1, wherein the ratio Al / Fe of the atomic composition percentage of aluminum to iron of the intermetallic compound is 3.1 to 8.2. The dissimilar metal bonding method according to claim 1, wherein the intermetallic compound is a metastable intermetallic compound containing Fe ₂ Al ₉ or FeAl ₆ . The aluminum material is a pure aluminum material or an aluminum alloy material containing aluminum as a main component,
The dissimilar metal joining method according to claim 1, wherein the steel material is a steel material containing 0.3% to 2% of carbon, or a stainless steel material.   The dissimilar metal bonding method according to claim 1, wherein the intensity or irradiation time of the electron beam is controlled to generate the intermetallic compound. Joint surfaces where aluminum and steel materials are in close contact with each other,
An aluminum melting portion which is offset from the bonding surface to the aluminum material side and in which only the aluminum material is melted and welded along the bonding surface by electron beam welding;
A dissimilar metal joining member, comprising: an intermetallic compound having a layer thickness of 0.5 to 2.0 μm generated on the joining surface side of the aluminum melting portion. The offset amount from the bonding surface is 0.50 to 1.25 mm,
The penetration width of the aluminum melting portion from the joining surface is 2 to 3 times the offset amount,
The dissimilar metal joining member according to claim 7, wherein a penetration depth of the aluminum melting portion is 5 times or more and 20 times or less of the offset amount.

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