JP2019126824A - Weld joined body - Google Patents

Abstract

To provide a weld joined body which requires no additional member, such as a filler material, and which is capable of ensuring weld strength between an iron-based metal member and an aluminum-based metal member.SOLUTION: A weld joined body 1 is one in which an iron-based metal member 2 and an aluminum-based metal member 3 are joined together by interposing therebetween a molten layer between dissimilar materials 4. The molten layer between dissimilar materials 4 has an intermetallic compound 5. The intermetallic compound 5 in the molten layer between dissimilar materials 4 has a volume ratio of 50% or less. The weld joined body satisfies an inequality: 2d>L, where L is a maximum length of the intermetallic compound 5, and d is a thickness of the molten layer between dissimilar materials 4.SELECTED DRAWING: Figure 1

Description

  The present disclosure relates to a welded joint in which an iron-based metal member and an aluminum-based metal member are welded.

  BACKGROUND OF THE INVENTION Conventionally, the invention relates to a welding technology of metal members, and in particular, a joined body (welded joint, welded joint) in which an iron-based metal member and an aluminum-based metal member are soundly welded and a method of manufacturing the joined body (See Patent Document 1 below).

  Patent Document 1 describes a welded joint in which an iron-based metal member and an aluminum-based metal member are joined via a welding portion (see the same document, claim 1 and the like). The weld has a melt percentage of the filler metal of 100% and contains a lower aluminum compound phase. Moreover, the metal component composition of the said weld part is 25 mass% or more and 70 mass% or less iron, 20 mass% or more and 40 mass% or less aluminum, 5 mass% or more and 25 mass% or less nickel, and 2 mass%. More than 40% by mass or less of other metal elements.

  According to the invention described in Patent Document 1, in the weld joint of the Fe-based metal member and the Al-based metal member, the formation of the brittle intermetallic compound in the weld can be suppressed to secure the welding strength. In addition, it is possible to provide a weld joint of Fe-based metal / Al-based metal having a higher manufacturing yield (that is, lower cost) than before by increasing the degree of freedom of welding temperature, and a method of manufacturing the joint See the literature, paragraph 0016, etc.).

Unexamined-Japanese-Patent No. 2017-080791

  In the invention described in the patent document 1, there is a problem that a weld metal is required in a joined body in which an iron-based metal member and an aluminum-based metal member are welded.

  The present disclosure provides a welded joint that does not require an additional member such as a filler metal and can secure the welding strength between an iron-based metal member and an aluminum-based metal member.

  A weld joint according to an aspect of the present disclosure is a weld joint in which an iron-based metal member and an aluminum-based metal member are joined via a melt layer between dissimilar materials, and the melt layer between dissimilar materials is an intermetallic It has a compound, the volume ratio of the intermetallic compound in the dissimilar material melting layer is 50% or less, the maximum length of the intermetallic compound is L, and the thickness of the dissimilar material melting layer is d. Inequalities: 2d> L is satisfied.

  The weld joint according to the above aspect of the present invention can be melted by defining the ratio and arrangement (discontinuously) of the intermetallic compound in the molten layer between dissimilar materials formed between the iron-based metal member and the aluminum-based metal member. Bonding strength can be secured without using additional members such as additives.

  According to the present disclosure, an additional member such as a filler material is unnecessary, and a welded joint that can ensure the welding strength between the iron-based metal member and the aluminum-based metal member can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic cross-sectional view of a welded joint according to an embodiment of the present disclosure. Typical sectional drawing of the weld joint of a comparison form. The graph which shows the conditions of spot welding of the welded joint body of an Example and a comparative example.

  Hereinafter, an embodiment of a welded joint according to an aspect of the present disclosure will be described with reference to the drawings.

  FIG. 1 is a schematic cross-sectional view of a welded joint 1 according to an embodiment of the present disclosure. The weld joint 1 of the present embodiment is characterized in that strength expression is made possible by defining the shape and size of the intermetallic compound 5 in the joint weld at the metallurgical joining of the different intermetallic compounds. Hereinafter, the welded joint 1 of the present embodiment will be described in more detail.

  The weld joint 1 is configured, for example, by metallurgically joining the iron-based metal member 2 and the aluminum-based metal member 3 via the dissimilar-material melting layer 4. Iron-based metal member 2 is, for example, iron, and aluminum-based metal member 3 is, for example, aluminum. Moreover, the dissimilar material fusion layer 4 is, for example, a zinc-containing layer. The iron-based metal member 2 is, for example, a galvanized steel plate that is generally used as an automobile material.

  The welded joined body 1 is, for example, a welded joint, that is, a molten layer 4 between different materials, by controlling the applied pressure, current, and time within a certain range during welding of the iron-based metal member 2 and the aluminum-based metal member 3. Form Further, by controlling the applied pressure, current, and time during welding to a certain range in this way, it is possible to reduce that the molten layer 4 between different materials, that is, the zinc-containing layer of the welded portion, is largely discharged to the outside.

  The inter-differential material molten layer 4, ie, the zinc-containing layer, contains, for example, the intermetallic compound 5 deposited in the layer. The maximum length L of the intermetallic compound 5 in the transverse direction perpendicular to the thickness d of the intermetallic material molten layer 4 is not more than twice the thickness d of the intermetallic material molten layer 4 (2d ≧ L). Moreover, the area ratio of the intermetallic compound 5 in the dissimilar-material fusion layer 4 is 50% or less. The intermetallic compound 5 is fragile as compared with the surrounding tissue, and the crack is easily developed as compared with the surrounding tissue.

  Hereinafter, the operation of the welded joint 1 of the present embodiment will be described based on the comparison with the welded joint X of the comparative embodiment. FIG. 2 is a schematic cross-sectional view of a welded joint X according to a comparative embodiment. In the welded joint X of the comparative form, as in the welded joint 1 of the present embodiment shown in FIG. 1, the iron-based metal member 2 and the aluminum-based metal member 3 are metallurgical through a molten layer 4 between different materials. The inter-differential-material melting layer 4 contains the intermetallic compound 5, which is constituted by being joined.

  In the weld joint X of the comparative embodiment, the maximum length L of the intermetallic compound 5 in the lateral direction perpendicular to the thickness d of the dissimilar material melting layer 4 is larger than twice the thickness d of the dissimilar material melting layer 4 is there. Moreover, the area ratio of the intermetallic compound 5 in the dissimilar material fusion layer 4 is greater than 50%. Thus, unless the fragile intermetallic compound 5 is discontinuous, the crack C propagates in the lateral direction, leading to breakage.

  On the other hand, in the welded joined body 1 of the present embodiment, the iron-based metal member 2 and the aluminum-based metal member 3 are joined via the dissimilar material molten layer 4, and the dissimilar material molten layer 4 is intermetallic compound 5. The volume fraction of the intermetallic compound 5 in the dissimilar-material fusion layer 4 is 50% or less. Furthermore, the welded joint 1 of the present embodiment satisfies the inequality: 2d> L, where L is the maximum length of the intermetallic compound 5 and d is the thickness of the molten layer 4 between different materials.

  Thereby, as shown in FIG. 1, the weak intermetallic compound 5 can be made discontinuous, the progress of cracks can be prevented, and the weld strength can be ensured. Therefore, according to this embodiment, an additional member such as a filler metal is unnecessary, and a welded joint 1 that can ensure the welding strength between the iron-based metal member 2 and the aluminum-based metal member 3 is provided. Can.

  The prior art requires an uncommon third material (Cu, fluoride, Ni, etc.) for avoiding the formation of the intermetallic compound 5, and is not practical from the viewpoint of cost and procurement. Also, for example, in the case where spot welding is premised, it is necessary to increase the amount of heat input at the time of joining of a material having a thickness, and there is a concern about the formation of the intermetallic compound 5. Furthermore, the prior art is not universal because the non-welding material and the shape of the filler material affect the formation of the intermetallic compound 5 in the welding portion.

  The reason why the above-mentioned problems occur in the prior art is that the prior art mainly aims to suppress the formation of the intermetallic compound 5 itself. On the other hand, in the welded joint 1 according to the present embodiment, the generation of the intermetallic compound 5 is controlled, and the shape is controlled and defined to enable the development of welding strength.

  The embodiment of the present invention has been described in detail with reference to the drawings, but the specific configuration is not limited to this embodiment, and there are design changes and the like without departing from the gist of the present invention. They are also included in the present invention.

[Example]
As shown in FIG. 3, spot welding was performed by applying current and pressure to the iron-based material and the aluminum-based material. Next, a tensile test was performed to apply a force in the shear direction with a material tensile tester. The results are shown in Tables 1 and 2 below. In bonding, particularly in melt bonding, the heat input largely affects, and the pressing force, the current, and the time are different depending on the material.

  In Example 1 and Example 2 shown in Table 1 and Table 2, the lateral maximum length of the intermetallic compound in the dissimilar material melting layer was not more than twice the thickness of the melting layer. On the other hand, in Comparative Example 1, the maximum length in the lateral direction of the intermetallic compound in the dissimilar material melting layer was at least twice the thickness of the melting layer.

Reference Signs List 1 welded joint 2 iron-based metal member 3 aluminum-based metal member 4 molten layer between dissimilar materials 5 intermetallic compound d thickness of molten layer between dissimilar materials L maximum length

Claims (1)

A welded joint in which an iron-based metal member and an aluminum-based metal member are joined via a dissimilar material fusion layer,
The molten layer between dissimilar materials contains an intermetallic compound,
The volume ratio of the intermetallic compound in the molten layer between different materials is 50% or less, where L is the maximum length of the intermetallic compound and d is the thickness of the molten layer between different materials, and the inequality: 2d> L A welded joint characterized in that

Images