JPH11291043A - Method for joining aluminum base member and iron base member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To firmly and closely join both members by thermal-spraying aluminum base thermal-spraying material on the surface of part to be joined of iron base member and executing TIG welding to the part to be joined with an aluminum member. SOLUTION: It is desirable to apply a fused diffusion treatment to the thermal- sprayed film layer formed on the surface of the part to be joined after thermal-spraying the aluminum base thermal-spraying material on the surface of the part to be joined of the iron base member. The fused diffusion treatment is executed by heating the surface of the iron base member to the fused diffusion temp. of the aluminum base thermal-spraying material and executing the fused diffusion to the thermal spraying padded aluminum film layer. At the time of executing the TIG welding, it is desirable to use an aluminum base filler metal. As the filler metal, Al-Si base or Al-Mg base can be used if the material is mutually easily fused between the aluminum thermal- sprayed film and the aluminum base member. The method for thermal-spraying the aluminum base thermal-spraying material to part to be joined of the iron base member, is mostly desirable to use a plasma thermal-spraying method which can execute the thermal-spraying in the reducing atmosphere.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a joining method for joining an aluminum-based member formed by die casting or extrusion to an iron-based member formed of stainless steel, steel, iron or the like. is there.

[0002]

2. Description of the Related Art Conventionally, it has been desired to develop a method for joining an aluminum-based member and an iron-based member by a simple welding technique. However, since the aluminum-based member and the iron-based member are materials that are hardly compatible with each other. Could not be welded directly.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and combines an aluminum-based member and an iron-based member firmly and tightly by combining a thermal spraying technique and a welding technique. It is intended to provide a joining method capable of joining.

[0004]

A method for joining an aluminum-based member and an iron-based member according to the present invention, which achieves the above object, is as follows.
The present invention is characterized in that an aluminum-based thermal spray material is sprayed on a surface of a portion to be joined of an iron-based member, and the aluminum-based member is joined to the portion to be joined by TIG welding. In this case, it is preferable that after the aluminum-based thermal spray material is sprayed on the portion to be joined of the iron-based member, the thermal spray coating layer formed on the surface of the portion to be joined is subjected to a melt diffusion treatment. In addition, when performing the TIG welding, it is preferable to use an aluminum-based filler as the filler.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific embodiments of the present invention will be described in detail. Examples of the aluminum-based member applied to the present invention include a member formed by a casting method such as die casting or gravity casting using an aluminum alloy, a member formed by an extrusion molding method, and the like. Are members formed by various forming methods using stainless steel, steel, iron or the like. There are no restrictions on the shapes of the aluminum-based member and the iron-based member.

[0006] The aluminum-based member and the iron-based member are sprayed with an aluminum-based thermal spraying material in advance on the surface of the portion to be joined of the iron-based member, and thereafter, are applied to the portion to be joined of the iron-based member. The aluminum-based members (the parts to be joined) are joined by TIG welding to be integrated.

[0007] As a method of spraying an aluminum-based spray material on a portion to be joined of an iron-based member, a gas spraying method, an arc spraying method, a plasma spraying method, or the like is known, but the present invention is limited to these spraying methods. However, any thermal spraying method can be used. However, in the gas spraying method or the arc spraying method, the aluminum-based sprayed material is oxidized to increase the inclusion of oxides. As a result, it is considered that the bonding strength is reduced and the diffusion process is difficult to perform. Plasma spraying, in which thermal spraying can be performed, is most preferable.

[0008] Since the aluminum sprayed coating formed on the surface of the portion to be joined of the iron-based member is not directly related to the joining strength, increasing the thickness does not necessarily improve the joining strength. In this case, it is preferable that the thickness is about 0.5 mm to 1.0 mm. If it is less than 0.50 mm, the iron-based member may be melted at the time of joining with the aluminum-based member. If it is more than 1.0 mm, the thickness of the base material becomes thin and the strength cannot be maintained.

Further, the surface of the portion to be joined of the iron-based member is
It is preferable to perform a series of pre-spraying treatments consisting of degreasing, washing, and blasting before spraying an aluminum-based spray material on a portion to be joined of the iron-based member. Then, the surface of the portion to be joined of the iron-based member is activated, and the adhesion with the aluminum sprayed coating is improved, and the anchoring effect between the aluminum sprayed coating is exhibited to further improve the adhesion. Will be able to do it. Incidentally, the adhesion between the aluminum-based member and the aluminum-sprayed coating at the portion to be joined of the iron-based member greatly affects the joining force between the aluminum-based member and the iron-based member.

As the aluminum spray material used in the present invention, it is preferable to use pure aluminum from the viewpoint of availability and price, but depending on the alloy component of the aluminum member to be joined, it is suitable for its composition. There is no problem even if an aluminum alloy is used.

Further, after the aluminum sprayed material is sprayed on the portion to be joined of the iron-based member to form an aluminum sprayed coating on the surface, and before the TIG welding, the surface of the portion to be joined of the iron-based member is formed. Is heated to the melting and diffusion temperature of the aluminum sprayed material so that the aluminum sprayed coating layer on which the spray coating is formed is subjected to a melt diffusion treatment.

At this time, when the surface of the portion to be joined of the iron-based member cannot be heated to the melting and diffusion temperature of the aluminum-based sprayed material, or when the thickness of the portion to be joined of the iron-based member is thin, distortion occurs due to heating. In such a case, the above-mentioned melt diffusion treatment cannot be performed. At that time, the surface of the portion to be joined of the iron-based member is approximately 0.1 mm thick using, for example, a Ni-Al-based bond coat material. The present inventors have confirmed that thermal spraying is preferable.

Thereafter, the portion to be joined of the aluminum-based member is welded to the surface of the portion to be joined of the iron-based member by TIG welding to integrate the iron-based member and the aluminum-based member. As a filler material used in TIG welding, an Al-Si-based filler material can be used as long as the aluminum sprayed coating formed on the surface of the portion to be joined of the iron-based member and the aluminum-based member can be easily fused to each other. But Al-
Mg may be used.

[0014]

According to the method for joining an aluminum-based member and an iron-based member according to the present invention, an aluminum-based sprayed material is sprayed on the surface of a portion to be joined of the iron-based member, and the aluminum-based member is applied to the joined portion. Are joined by TIG welding, so that an aluminum-based member and an iron-based member, which has been impossible in the past, can be joined by welding.

Moreover, since the aluminum-based member and the iron-based member are welded to each other via the aluminum spray coating layer, the aluminum-based member and the iron-based member can be firmly and tightly joined. By the way, on the inner periphery of the cylindrical part (inner diameter: 27.4 mm) gravity-cast using aluminum alloy (AC2A) as the aluminum-based member,
As a result of a tensile fracture test when joining by the above-described method of the present invention using a form in which the outer periphery of one end of a stainless steel (SUS304) pipe (outer diameter: 25.4 mm) is inserted as an iron-based member, 13 KN or more The breaking strength was obtained.
Further, FIG. 1A shows a macro photograph of the cross section of the joining portion obtained at this time. FIG. 1B is a microphotograph in which the cross section of the joint portion (stainless steel (SUS304) and the sprayed layer) shown in FIG. 1A is further enlarged 200 times.

Further, according to the method for joining an aluminum-based member and an iron-based member according to the second aspect, after the aluminum-based sprayed material is sprayed on the portion to be joined of the iron-based member, the aluminum-based member is formed on the surface of the portion to be joined. When the TIG welding of the part to be joined of the aluminum-based member to the surface of the part to be joined to the iron-based member is performed, the melt-spreading process is applied to the sprayed coating layer thus formed. Therefore, it is possible to improve the bonding strength and airtightness.

Further, according to the method for joining an aluminum-based member and an iron-based member according to the third aspect, an aluminum-based filler material is used at the time of TIG welding. It is possible to improve the conformity between the aluminum sprayed coating layer formed on the surface of the portion and the aluminum-based member, and it is possible to further improve the bonding strength and airtightness.

[Brief description of the drawings]

FIG. 1 (a) shows a stainless steel (SUS) by the method of the present invention.
304) is a macrophotograph of a cross section at a joined portion where an aluminum alloy (AC2A) casting is joined. (B)
The joint shown in (a) (stainless steel (SUS304)
And a thermal sprayed layer) are microphotographs in which the cross section is further enlarged 200 times.

 ──────────────────────────────────────────────────の Continuing from the front page (72) Inventor Mineo Okamoto 3-2-26- 302

Claims (3)

[Claims] 1. An aluminum-based member and an iron-based member, wherein an aluminum-based thermal spray material is sprayed on a surface of a portion to be joined of the iron-based member, and the aluminum-based member is joined to the portion to be joined by TIG welding. How to join with system members. 2. The method according to claim 1, wherein after the aluminum-based thermal spray material is sprayed on the portion to be joined of the iron-based member, a melt-diffusion treatment is performed on the thermal spray coating layer formed on the surface of the portion to be joined. A method for joining an aluminum-based member and an iron-based member according to claim 1. 3. When performing the TIG welding,
2. An aluminum-based filler material is used.
A method for joining an aluminum-based member and an iron-based member according to the above description.