JPS59212159A - Production of aluminum alloy casting - Google Patents

Abstract

PURPOSE:To obtain an Al having improved high-temp. hardness, wear resistance, etc. by charging a molten Al alloy into a metallic mold holding a porous metallic body, heating and holding the Al alloy casting material embedded by casting by a high-pressure solidification method and forming a compd. layer contg. Al at the boundary between the porous metallic body and the Al alloy. CONSTITUTION:A porous metallic body consisting of a foamed metal of Ni, Cu, etc. is held in a metallic mold. The volume rate of such porous metallic body is 3-50% and the size of holes is preferably 0.05-1mm.. The melt of an Al alloy is charged into the metallic mold in such a state and is pressurized under >=400kg/cm<2> to form the Al alloy casting material embedded with the porous metallic material by casting by a high-pressure solidification method. Such Al alloy casting material is subjected to a heat treatment for 1-10hr at 450-550 deg.C to form a compd. layer of the Al and the metal (e.g.; Ni) of the porous metallic body at the boundary between the porous metallic body and the Al alloy, by which the intended alloy casting is obtd. The volume rate of the compd. layer in the part embedded with the porous metallic material by casting is made preferably 1-80% and the thickness of the metallic compd. layer is preferably >=10mu.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention produces an intermetallic compound layer on a part of an aluminum alloy square material to achieve high temperature hardness.
This invention relates to a method for producing aluminum horn alloy castings with improved wear resistance.

(Prior art) In general, diesel engine pistons are made of high-silicon aluminum alloy (J), which has low thermal expansion and excellent wear resistance.
IS AC8A, etc.), but for example, the entire bone is affected by the erosion of high-pressure fuel injected from the ID fuel injection nozzle on the piston head, and the piston/ring groove corresponds to the gas pressure. The repeated loading of the piston ring acts, and in these 1111 minutes, the high temperature hardness improves and becomes 1llI11'1LJ・[5'1'1(I(1
]J Corrosion Resistance), Settling Resistance Gold Reform - No, it is required.

One of the methods for strengthening the surface of aluminum alloy castings is tie casting. However,
In the case of gravity casting, when the cast body is a metal porous body having continuous pores or a metal fiber I, TT molded body, it is not possible to fill the internal pores of the metal porous body with molten aluminum alloy, and the cast body is The adhesion between the body surface and the aluminum alloy is insufficient, and the joint strength between the two is insufficient, leading to cracks and peeling when heat load is applied9.On the other hand, in the case of die-casting, Adhesion,
Although the filling properties are improved, air entrainment into the product is unavoidable, and it is difficult to heat treat the cast product because blisters occur due to air expansion during heating.
It is not possible to improve the strength of the aluminum alloy, or to improve the wear resistance or tarnishing resistance due to the formation of intermetallic compounds (solid phase diffusion layer).

1, JP-A-53-3], No. 014, a heat-resistant porous material such as a Ni-Cr based sintered material is cast into an aluminum alloy using a full high-pressure solidification casting method, and the inside of the pores of the porous material is There are some products that are filled with aluminum alloy. However, with this material, the bonding strength between the aluminum alloy and the porous body is only 1 insufficient, and since almost no intermetallic compounds are formed, the sintered material alone has low high-temperature hardness and poor wear resistance. , the effect of improving stickiness resistance is small.

Furthermore, the technology disclosed in JP-A-54-1.51715 immerses a porous metal such as nickel in molten aluminum, seals the surface, and forms a compound layer of nickel and aluminum on the surface through heat treatment. However, this metal porous body is then cast in an aluminum alloy, and a compound layer improves heat resistance and corrosion resistance. However, in this case, the metal porous body is simply cast in an aluminum alloy and twisted. The bonding strength between the above compound layer and the aluminum alloy is insufficient, and the compound layer is formed deep into the surface of the porous metal body, so the effect of improving heat resistance (high 61M hardness) and corrosion resistance is insufficient. be.

(Objective of Invention 1) In view of the above circumstances, the non-explosion
We would like to provide a complete manufacturing method for aluminum alloy castings with improved high-temperature hardness by generating an intermetallic compound layer while increasing the bonding strength with the alloy, and completely improving the wear resistance. It is something to do.

(Structure of the Invention) In the method for manufacturing an aluminum alloy casting of the present invention, 1. The entire metal porous body is held in a mold, 1' the entire molten aluminum alloy is injected into the mold, and then a pressurizing force of 'OOkg/ o
r: An aluminum alloy casting element 4J surrounded by a metal porous body is formed by the above-described high-pressure solidification casting method, and then the aluminum alloy casting material is heated to 1 to 1 at a temperature of /150 to 550°C.
7. The above-mentioned metals are heated for 0 hours and subjected to an intermetallic compound generation treatment that generates a compound layer of aluminum and the metal of the porous metal body at the boundary between the porous metal body and the aluminum alloy. The porous body is made of nickel, copper or (
l-L, ], foamed σ group-t/this is made of a metal fiber molded body made of metals, etc., and the pores are completely filled with aluminum alloy by high-pressure solidification and cutting in the i) S state. The high-pressure solidification casting method of forming and molding an aluminum alloy material all around it involves charging a porous metal body, melting the aluminum alloy in a mold, and then melting the aluminum alloy into a mold. Pressure force 400 kid/c! ? 600 or more (e.g. 600
kg/cni or 1000 kid/c#
) to solidify the liquid in a state where the force is -. If this pressure is less than 400 ky/art, aluminum
Solidification structure and mechanical properties of the ram alloy casting itself:
＋p↓: 1s The effect of pressurization is small and its quality is guaranteed t+, 'j:V <, also, the adhesion between the porous metal body and the aluminum alloy is insufficient, resulting in intermetallic compound generation treatment. However, it is difficult to form a complete layer of a good compound of aluminum and the metal of the porous metal body at the boundary between the porous metal body and the aluminum alloy.

However, in the above-mentioned high-pressure solidification casting method, in order to improve the filling properties of the molten aluminum alloy, the porous metal body may be preheated before pouring and pressurizing.

The shape and volume ratio of the metal porous body are arbitrary, but
The volume fraction Vf is 3 to 50%, that is, the porosity is 50
~97% is preferable, especially a volume fraction Vf of 5 to 4.
．． 0% is optimal. The volume fraction Vf of the metal porous body decreases with the formation of the compound layer, and is 3
If it is less than %, the density of the intermetallic compound layer formed on the surface layer and inside will decrease, and if the volume fraction Vf exceeds 50, the volume fraction of the intermetallic compound layer will be 80% or more, which is undesirable. In addition, the pore diameter of the metal porous body is 0.0
5 to J dragon is preferred; if the pore diameter is less than 0.05 am, it is difficult to fill the pores with aluminum alloy, and if it exceeds 1 m1i, the density of the intermetallic compound layer decreases, which is not desirable.

On the other hand, the compound layer obtained by subjecting the aluminum alloy casting material to the intermetallic compound generation treatment is an intermetallic compound of aluminum in the aluminum alloy and the metal of the metal porous body, that is, in the case of a nickel-based metal porous body, It is a compound layer of aluminum and nickel, in the case of a copper-based metal porous body, it is a compound layer of copper and aluminum, and in the case of an iron-based metal porous body, it is a compound layer of iron and aluminum, The metal of the porous metal body is obtained by diffusing into an aluminum alloy. This intermetallic compound generation treatment involves heating and holding at a temperature of 450 to 550°C for 1 to 10 hours, and the heating temperature is: If it is less than 450'C, it takes a long time to form the entire intermetallic compound layer and is not economical, and if it exceeds 550C, the strength of the aluminum alloy casting itself decreases. Indeed, if the heating time is less than 1 hour, it is not possible to form a sufficient intermetallic compound layer, and if it exceeds 10 hours, the formation of the intermetallic compound layer is almost saturated, which is not economical.

In this intermetallic compound generation treatment, water quenching may be performed after the heating, and further tempering treatment (T6 treatment, etc.) may be performed in order to also serve as solution treatment of the aluminum alloy.

The volume fraction Vf of the compound layer in the part where the metal porous body is cast is preferably 1 to 80%. If the body M ratio Vf is less than 1 factor, sufficient effects on high temperature strength, wear resistance, and retardation properties cannot be obtained, and if it exceeds 80, the amount of aluminum alloy intervening is small. , the adhesion strength (joining strength) with the aluminum alloy (3J4) when subjected to thermal stress etc. decreases, and the hardness increases, resulting in poor workability during full machining.Furthermore,
The thickness of the above-mentioned intermetallic compound layer is preferably 10μ or more in order to improve high-temperature strength, wear resistance, and retardation properties.On the other hand, the thickness of the intermetallic compound layer cast through the porous metal body is Q, 1 m + 1
It is preferable that the number is 1 or more, and if it is less than 0.01, it will not be possible to maintain good wear resistance and set resistance for a long time.

(Effect of the invention) The pores of the metal porous body are filled with aluminum alloy by high-pressure solidification casting method, and the cast metal porous body and the aluminum alloy are fully adhered to each other, and the metal porous body and aluminum are bonded by intermetallic compound generation treatment. By forming the entire compound layer of aluminum and the metal of the metal porous body at the boundary with the alloy, the bonding strength between the metal porous body and the aluminum alloy is high.
Moreover, inside the metal porous body, a compound layer with excellent thermal properties and high temperature hardness is formed at the boundary between the metal and the aluminum alloy filled in the pores, resulting in excellent wear resistance and fatigue resistance. You can have enough,
Durability can be completely improved (Example) Next, an example of manufacturing a piston for a diesel engine according to the present invention will be shown.

Fig. 1 shows an aluminum alloy piston l made by the method of the present invention, in which the outer circumference of the piston body 2 has a top ring groove 3 in which a top ring is fitted, a secondary ring groove 4 in which a secondary ring is fitted, and an oil ring. An oil ring groove 5 into which the oil ring is fitted is formed respectively.

The top ring groove 3 of the piston 1 is provided by a ring support part 6, and the piston body 2 other than the ring support part 6 is made of aluminum alloy.

The production of the piston 1 begins with the steps shown in FIG.
The ring support member 6 is entirely molded by a metal strip body. In this case, since the top ring groove 3 is formed by cutting in post-processing, it is formed into a simple ring shape.

As shown in FIG. 3, this ring support member 6 is charged and held in a mold 7 consisting of an upper mold 7a, a lower mold 7b, and an intermediate mold 7C, and is placed in a cavity 8 in this mold 7. The aluminum alloy molten metal is poured from the pouring lower d opened in the lower mold 7b, and a pressing force of 400 kg 7C, 4 or more is applied to this molten metal.
High-pressure solidification casting is performed by maintaining high pressure until the molten metal solidifies.

As a result, as shown in FIG.
A miniature alloy casting material 9 is formed by casting a ring support member 6 made of a metal porous body into a part of the metal porous body. The pores of the glue/glue support part 6 are filled with aluminum alloy in the pores of its metal porous body.

Next, this aluminum alloy υ, 5 elements iA9'tr:
It is charged into a heating furnace and subjected to intermetallic compound generation treatment by heat treatment to generate an intermetallic compound layer at the boundary between the porous metal body and the aluminum alloy in the ring support portion 44', and at the same time, the aluminum alloy base material is subjected to solution treatment. After joining,
Machine cutting is performed to form the top ring groove 3 in the first ring support member 6 such as a, and to form the entire secondary ring groove 4 and oil ring groove 5.

Figures 5 to 9 show photos of the metallographic structures of aluminum alloy castings produced under various conditions shown in the table below, taken with an optical microscope.
The amount of M in composition 1 is as follows: 1゜A(+C
u Si Mg l'(・Ni remainder 10
11909 0.22 1+ Also, the thickness of the copper plating of the nickel porous body -\ in Fig. 9 is 5 to 10 t.
z, in FIGS. 5 to 8, the multi-area matrix with spots is an aluminum alloy, a nickel metal porous body with a remaining intermediate white layer bordered by a gray layer,
A gray layer (Ni-rich) and a white layer (Al-rich) are formed in the form of a film on the outer periphery of this nickel-gold porous body.
is the compound layer. In Figure 9, all the points are
The multi-area matrix is aluminum alloy, the white layer is a nickel metal porous material, and the gray remaining border line on the outer periphery is the copper plating layer, which is formed on the outer periphery of this layer. The dark gray layer (Cu-rich) and the even dirtier gray layer (Al-rich) are compound layers. .

In addition, in Figures 6 to 9, the part of the inside of the Ninokel porous body that is black is the appearance of graphite that was attached to the nickel porous body during the manufacturing process of the nickel porous body. In Figure 6 of the octopus, there is less residual nickel porous material (white layer between gray layers) than in the other photographs because the 1M thickness of the nickel porous material itself is thin. Even after heating, the residual nickel porous material was reduced.

On the other hand, as shown in Figure 8, the entire interior of the nickel porous body is black, which is a closed space and is not filled with aluminum alloy. High-temperature hardness of compounds As is clear from the above-mentioned 5 studies, in the present invention, aluminum alloy castings according to the present invention are coated with a metal porous material on the outside or in the load-receiving part by high-pressure solidification casting method, and Through intermetallic compound generation treatment, an intermetallic compound layer with excellent high-temperature hardness and heat resistance is formed at high density on the surface layer of the aluminum 9L-containing casting, resulting in a compound with a heat exchange rate of 1'1. Because of the complete formation, the melting point of the aluminum alloy with 7 trix is prevented, even though the aluminum alloy is prevented from locally melting in the bath. Cretability is improved due to improved high-temperature hardness.

It should be noted that the aluminum and alloy castings of the present invention are not limited to the 4-ton bee for Diesel FTSNO's as in the above embodiment.

[Brief explanation of the drawing]

Fig. 1 is a partially cross-sectional front view of an aluminum alloy piston manufactured by the method of the present invention; Fig. 2 is a perspective view of a ring support member; Figure 4 is a cross-sectional view of the main part of the aluminum alloy material; Figures 5 to 9 are optical micrographs showing examples of the metal structure of aluminum alloy castings. Porous body (ring support member) 7...
Mold mold...Aluminum alloy casting 81 Figure 5 Figure 8

Claims (1)

[Claims] (]) Gold 4: The entire porous metal body is held in ν, and the entire molten aluminum alloy is injected into the mold, and then the pressing force/
An aluminum alloy casting material in which a metal porous body is cast is formed by a high-pressure solidification casting method of 100 kg/crI or more, and then the aluminum alloy casting material is 450 to 55
0°C nl, 1 degree] to 10 hours to form a compound layer of aluminum and the metal of the porous metal body at the boundary between the porous metal body and the aluminum alloy. A method for manufacturing aluminum alloy castings characterized by
(