JP2677413B2 - Filler for surface hardening of aluminum materials - Google Patents

Description

TECHNICAL FIELD The present invention relates to a filler material, and more particularly to a filler material used to harden the surface of an aluminum material to form an aluminum alloy material having excellent wear resistance.

In this specification, the term aluminum is used to include its alloy.

As is well known in the prior art, aluminum is significantly lighter than commonly used iron-based materials, etc., and also has excellent heat conduction characteristics and excellent corrosion resistance. It is becoming widely used as a mechanical part. However, aluminum is generally inferior in wear resistance to iron-based materials, and this has been a major obstacle when replacing iron-based members with Al alloy members for the purpose of weight reduction in automobiles and the like.

Therefore, conventionally, as a measure for improving the wear resistance of an aluminum material applied to a site where the wear resistance is required, an attempt has been made to form a surface hardened layer having excellent wear resistance on the surface of the aluminum material. As one of the methods for forming such a surface-hardened layer, the present applicant has previously proposed that the surface of an aluminum material is externally supplied together with one or more kinds of borides or silicides and a high density such as a laser beam. We proposed a method of alloying the surface of an aluminum material by irradiating it with an energy heat source and melting it locally (Japanese Patent Application No. 63-63).
-304519). According to this method, a surface alloyed layer having high hardness can be obtained and there is no risk of peeling of the layer,
It is possible to provide an aluminum material suitable as a wear resistant product.

However, the above method has the following drawbacks in forming the alloyed layer.

That is, in the above method, the boride or silicide is supplied to the surface of the aluminum material by powderizing the powder and coating the surface of the aluminum material with a binder before irradiation with a laser beam or the like. It is carried out by directly putting it into the melting part during irradiation of the beam, etc.
In the former coating method, the applied powder may drop or come off depending on the welding position. Also, the coating workability was not good. Furthermore, there is a possibility that defects such as pores may remain in the surface hardened layer depending on the kind of binder. On the other hand, in the latter direct charging method, it is difficult to continuously and stably supply the powder to the melting portion, and particularly when the amount is small, the difficulty is particularly increased. There is also a method of supplying powder by placing it on a carrier gas of a melting heat source as one of direct charging methods, but in this case, it is possible to affect irradiation of the heat source or to supply an arbitrary amount to a target position. There were drawbacks such as difficulty.

The present invention has been made to solve such drawbacks all at once, and can stably supply the powder for forming the surface hardened layer to a target position without being restricted by the welding posture, and thus, the aluminum material The purpose of the present invention is to provide a surface-hardened layer reliably and efficiently on the surface, and to provide a material therefor.

Means for Solving the Problems As a material for achieving the above object, the present invention shows, in reference to the reference numerals in the drawings, one kind or two or more kinds in an inner hollow part (2a) of an aluminum skin material (2). The present invention provides a filler material (1) for surface hardening of an aluminum material, characterized in that the powder (3) of boride or silicide is stored in a filled state.

As shown in FIG. 1, a filler material (1) according to the present invention
Are generally provided as welding rods or cores. Usually, the outer diameter is set to about 2.4 to 3.2 mm when used for TIG welding, and the outer diameter is set to about 1.2 to 2.4 mm when used for MIG welding. The filler material (1) has a hollow portion (2
an aluminum skin (2) having a) and the hollow part (2)
It consists of a powder (3) of a compound of boride or silicide, that is, a metal element and boron or silicon, which is contained in a) in a filled state. Thus, the reason why the powder (3) is stored in the inner hollow portion of the aluminum skin material (2) in a filled state is to keep the powder in a fixed state. Here, the composition of the aluminum skin material (2) is not particularly limited,
Pure Al, 5052 alloy, 5083 alloy and other alloys may be appropriately selected and used in relation to the composition of the aluminum material on which the surface hardened layer is to be formed.

The boride or silicide powder (3) housed in the inner hollow part (2a) of the aluminum skin (2) in a filled state is alloyed on the surface of the aluminum material by melting to form an alloyed layer having high hardness. To fulfill. Boride and silicide are equivalent to each other in terms of producing such an effect, and it is sufficient to use at least one of these compounds.
Examples of preferred borides include TiB ₂ , ZrB ₂ , NbB ₂ , CrB ₂ ,
TaB ₂ , NiB, etc. may be mentioned. On the other hand, examples of preferable silicides include Mg ₂ Si, TiSi ₂ , MoSi ₂ , NbSi ₂ and CrSi ₂ . As described above, the boride or silicide powder in the filler metal is an essential constituent element for improving the hardness of the alloyed layer formed by welding. Carbides such as WC, TiC and TiN,
It is also conceivable to use a nitride such as ZrN. However, the reason why the boride or nitride powder is used is as follows.
That is, when the powder of WC or TiN is used, the wettability with the aluminum material is poor and a good alloyed layer cannot be formed, but when the boride or silicide powder is used, the aluminum material becomes The wettability is excellent, the surface is smooth, and an extremely excellent alloyed layer can be formed. This is because B in the boride and Si in the silicide are Al when the alloyed layer is formed.
This is considered to be because it has the effect of improving the wettability with.

Also, in order to further improve the wettability, 5 to 30% of Al powder with a particle size of 50 to 200 μm is used together with boride and silicide powder.
It may be mixed to some extent.

The filler material (1) shown in FIG. 1 may be manufactured, for example, as follows. That is, a long plate-shaped aluminum skin (2) having a predetermined thickness as shown in FIG. 2 is roll-formed into a semicircular cross section as shown in FIG. 3, and the powder (3) is formed in the recess. After filling with the above, it can be performed by further forming a circular cross-section as shown in FIG. 4 and welding the both ends closed portion (4). It should be noted that after that, drawing processing or the like may be performed as necessary. Here, the quantitative ratio of aluminum and powder (3) in the filler material (1) is the skin material (2).
It can be changed by changing the wall thickness. By providing the aluminum core material (5) having the same composition as the skin material at the axial center of the filler material (1) as shown in FIG. 5 without changing the thickness of the aluminum skin material (2). You may change the ratio of aluminum and powder. Also, the sixth
As shown in the figure, two or more hollow portions (2a) (2a) in the axial direction may be provided inside the aluminum skin material (2) to accommodate the powder (3) in a filled state. 5 and 6, parts having the same names as those of the filler material shown in FIG. 1 are designated by the same reference numerals.

The filler material according to the present invention is supplied to the surface-melting portion of the aluminum material by means of TIG welding, MIG welding or the like as in ordinary welding. After melting, the molten aluminum material is solidified in a short time, and boride or silicide particles are uniformly and densely dispersed or agglomerated in the Al matrix of the aluminum material to form an alloyed layer on the surface. Thus,
Since boride and silicide themselves have extremely high hardness, the alloyed layer as a whole exhibits high hardness and has excellent wear resistance.

The aluminum material having the hard alloyed layer formed on the surface thereof is then machined into a final product shape if necessary and put into practical use as a wear resistant part. The composition of this aluminum material is not particularly limited, not to mention pure Al.
2000 series other aluminum wrought materials or AC8A, AC2B
Aluminum casting materials and the like can be used as appropriate.

EFFECTS OF THE INVENTION As described above, the present invention provides a filler material in which powders of one or more kinds of borides or silicides are contained in an aluminum skin material in a filled state. By welding the surface of the aluminum material using the filler, a hard alloyed layer in which the Al matrix and the boride or silicide particles are alloyed can be formed. As a result, it is possible to provide an aluminum material suitable as a wear resistant part required for automobiles and the like. Moreover, since the boride or silicide powder is supplied as a filler material when forming the surface-hardened layer on the aluminum material, unlike the conventional coating method, the applied powder falls depending on the welding position. It is possible to eliminate the inconvenience that it may come off or peel off, and it is possible to form a surface-hardened layer without being restricted by the welding position. For example, when the aluminum material is a rotating object, the surface-hardened layer is formed. Is possible. Further, since it is not necessary to use a binder for applying and holding the powder at all, the possibility that defects such as pores remain in the surface hardened layer can be eliminated. Further, since the coating process itself is not required, the work efficiency can be improved and the productivity can be improved. Furthermore, in the coating method, since the heat source is directly irradiated to the powder, the cleaning action of the aluminum material cannot be obtained,
The filler material according to the present invention can be expected to have an action of cleaning an aluminum material when an AC power source or the like is used. Furthermore, since the powder supply amount can be easily adjusted by supplying the powder as the filler, an arbitrary amount of powder can be continuously and stably supplied to the target position regardless of the supply amount.

(Example 1) 1 in the hollow center of the aluminum skin made of A1100
A long filler metal containing TiSi ₂ powder having a diameter of up to 10 μm in a filled state was manufactured. The filler material was manufactured by forming a large diameter member by roll forming as described with reference to FIGS. 2 to 4 and then performing drawing. The outer diameter of the filler metal (1) is 1.6 mm, the wall thickness of the aluminum skin (2) is
It was 0.5 mm.

On the other hand, as an aluminum material for forming a surface hardened layer
A 7.5 mm thick × 40 mm wide × 100 mm long test piece made of AC8A casting alloy was prepared. Then, as shown in FIG. 7, a shallow groove (7) having a depth of 0.5 mm was formed in the longitudinal direction of the central portion of the test piece (6).

Next, as shown in the figure, a TIG welding machine (8) was used to continuously supply the filler material from the filler material feeder (9) while the semi-automatic TIG was applied to the groove (7) of the test piece. Welded. In the figure, (10) is the weld. Welding speed is 100mm / min
And

After the welding, when the microstructure of the solidified welded portion was examined, an alloyed layer having a smooth surface and no defects was formed over the entire groove portion. And these alloyed layers are
TiSi ₂ has a relatively uniformly densely dispersed portion and a lumped portion, and the hardness of the entire alloyed layer is from Hv81 to 824 (load 1
It was 00g). Moreover, no cracks or pores were found in the alloyed layer or at the interface between the alloyed layer and the aluminum material. On the other hand, when the hardness of the aluminum material alone was examined, it was Hv30 (load 5 Kg).

Example 2 A test was conducted under the same conditions as in Example 1 except that TiB ₂ powder having a diameter of 1 to 5 μm was used instead of TiSi ₂ powder. A layer was formed. The hardness of the alloyed layer is Hv250-3200 (load 500g).
Met.

Example 3 Instead of TiSi ₂ powder, ZrB ₂ powder having a diameter of 1 to 5 μm and 1 to 5 μm were used.
When a test was conducted under the same conditions as in Example 1 except that a mixed powder of MoSi ₂ powder having a diameter of 2 μm was used, a similarly alloyed layer having no defect was formed. The hardness of the alloyed layer is Hv150 ~ 2
It was 800 (load 500g).

(Comparative Example 1) A test was performed under the same conditions as in Example 1 except that a TiC powder having a diameter of 5 to 10 µm was used instead of the TiSi ₂ powder.
A turtle-shaped crack was observed on the surface, and part of the surface was peeled off.
Moreover, just below the alloying layer, there is a molten region of the base material Al only,
It was confirmed that the wettability with Al was poor.

As can be seen from the above test results, when the additive according to the present invention is used, it is possible to easily and reliably form an alloyed layer having extremely high hardness and therefore naturally excellent wear resistance on the surface of the aluminum material. I was able to confirm.

[Brief description of the drawings]

FIG. 1 is a sectional perspective view showing an example of the filler material according to the present invention, and FIGS. 2 to 4 are for explaining a manufacturing process of the filler material shown in FIG. Is a cross-sectional view of the aluminum skin material in a plate state, FIG. 3 is a cross-sectional view of a semi-circular shape filled with mixed powder, and FIG. 4 is a cross-sectional view of the aluminum material with both ends closed. FIG. 5 is a sectional view showing a modified example of the filler metal, FIG. 6 is a sectional view showing another modified example, and FIG. 7 is a perspective view schematically showing the welding process of the test piece in the example. (1) …… filler metal, (2) …… aluminum skin, (2
a) ... Hollow part, (3) ... Mixed powder.

Claims (1)

(57) [Claims] 1. A filler material for surface hardening of an aluminum material, characterized in that one or more kinds of boride or silicide powders are contained in a filled state in an inner hollow portion of the aluminum skin material. .