JPH02133162A - Alloy casting - Google Patents

Abstract

PURPOSE:To enhance the wear resistance and lubricity of the alloy casting by adding particles having good wettability to a molten alloy, subjecting this molten metal to mechanical stirring, rapidly cooling and solidifying the molten metal. CONSTITUTION:The particles 4 having good wettability are added to the molten metal 2a melted in a crucible 1. This molten metal 2b is stirred by a mechanical stirring member 5. A plug 9 is thereafter removed and the molten metal 2b is poured through a feed port 10 into a casting mold 11. The molten metal 2b is rapidly cooled and solidified by the cooling effect of a water cooling cylinder 12. Fibrous high melting metals or alloys are added to the melt of a low melting alloy and the molten alloy is mechanically stirred and rapidly cooled and solidified. The wear resistance and lubricity of the alloy casting are enhanced in this way.

Description

[Detailed description of the invention] a. Industrial application field The present invention relates to alloy castings.

b. Prior Art Conventionally, light alloys such as Aff1-Mg alloy have been widely used as alloy castings. In the case of this type of alloy casting, when the molten metal is self-solidified (91 times solidified), the crystal grains become directional and tend to grow large.

Materials with such directional properties have directional properties in strength and toughness, resulting in a weak direction.

Therefore, in order to solve this problem, the molten alloy is rapidly solidified to make the crystal grains finer, thereby eliminating the directionality and increasing the strength and toughness. In the case of Affi alloy, 0.01 to 0.1% by weight of P or Na is added to further improve strength and toughness.

On the other hand, low melting point (660″C) alloys (e.g. Al, Mg
In the case of castings (Zn, pb, Sn+ Bi, etc.), the molten metal is cooled and solidified, and heat treatment (for example, A1
For alloys, JIS standards require natural aging after solution treatment.
Standard T4 treatment or JIS standard T6 treatment, which involves artificial aging hardening after solution treatment, is performed. In addition, fibrous materials (e.g. alumina, carbon, etc.) and short fibers (whiskers) are produced by pressure casting (molten metal forging).
It is also possible to strengthen the steel by impregnating it with an alloy.

C1 Problems to be Solved by the Invention However, even if the crystals on the surface of the castings obtained by rapidly cooling and solidifying the molten metal are fine, the crystals inside are crystalline.

Since it is not cooled, the internal crystals do not become fine, and therefore it is not possible to obtain a casting whose crystal diameter is uniform throughout.

In addition, the fact is that the effect of grain refinement by adding P or Na is not very large, and P is difficult to handle alone, so it is added in the form of P-Fe, P-Cu, P-Ni, etc. Therefore, component management is extremely difficult. Besides, P
There is also the problem that alloy performance deteriorates when added. On the other hand, Na is difficult to handle because of its high reactivity.

Further, when performing pressure forging as described above, a large pressing force (for example, about 50 kg/c-) is required. Moreover, when performing pressure forging, it is necessary to perform setting operations such as applying tensile force to the fibrous material and intertwining short fibers with each other and forming them with a binder, which is extremely difficult. The reality is that it is difficult.

The present invention has been made in view of these various problems, and its purpose is to provide an alloy casting with excellent strength and toughness in which crystal grains are uniformly refined and have no directionality. There is a particular thing.

Another object of the present invention is to provide an alloy casting having sufficient strength and toughness that can be composited with fibrous metals or alloys without applying high pressure as in pressure forging.

d. Means for Solving the Problems In order to achieve the above-mentioned object, in the present invention, particles with good wettability are added to the molten alloy, and the molten metal is rapidly cooled and solidified by mechanical stirring. There is. Further, in the present invention, a fibrous high-melting point metal or high-melting point alloy is added to a molten metal of a low-melting point alloy, and the molten metal is mechanically stirred to rapidly solidify it.

Embodiments of the present invention will be described below with reference to the drawings.

1 to 3 show a first embodiment of the present invention, and schematically illustrate the manufacturing process of an A2 alloy casting made of an Aff1-Mg light alloy or the like.

First, as shown in FIG.
Heat and maintain at a moderate temperature. As a result, the alloy casting material 2 is melted in the crucible 1 and becomes a molten metal 2a of A1 alloy (see FIG. 2). After that, as shown in FIG. 2, the molten metal 2a has good wettability (wetting angle of 100" or less) and a particle size of 0.05".
0.5-20% by volume of ~10μ particles 4 are added. The particles 4 have a melting point of 1000° C. or higher, such as Zr+Fe, Co+Ni, and Ti.

A pure metal, an alloy, or a ceramic such as V+ Cr, Mo+-, etc., which wets the molten metal 2a but does not completely melt itself, is used.

Next, as shown in FIG. 3, the molten metal 2b to which particles 4 were added
is stirred by mechanical stirring means 5. The stirring means 5 consists of a stopper 6 made of a rod, and a plurality of stirring members 8 arranged in parallel around the stopper 6 and each having a spiral groove 7 at the lower end. are raised and lowered together in the vertical direction by a lifting means (not shown). Furthermore, the above-mentioned stirring member 8 is configured to be rotated around its axis by a driving means not shown. When the stirring means 5 is lowered and the lower end of the stopper 6 comes into contact with the bottom of the crucible 1, the lowering operation is stopped and the stirring member 8 is lowered from 100 to IO+0.
It is rotated at rotational speeds of 00r, p, and s+, thereby uniformly dispersing the particles 4 in the molten metal 2b.

After mechanically stirring the molten metal 2b to which the particles 4 have been added in this way, the stopper 9 on the bottom wall of the crucible 1 is removed and the hot water supply port 1 is removed.
The molten metal 2b is poured into the mold 11 through the water cooling cylinder 1.
The molten metal 2b is rapidly solidified by the cooling action of 2, and is recovered as a lump-like aggregate, that is, an alloy casting 13. In this way, the uniformly dispersed particles 4 become the core of the primary crystal grains during solidification, so that an alloy casting 13 having finer crystal grains than in the conventional case can be obtained.

In addition, when the molten metal 2b is allowed to solidify naturally (nine times) without being rapidly cooled, the crystal grains 14 are distributed from the inner wall surface 11a of the mold 11 to the upper central part A, which becomes the final solidified part, as shown in FIG. As a result, the crystal grains grow long toward the grain, and do not become fine crystal grains.

In this example, particle 4 has high hardness (IV250 or higher)
Using self-lubricating particles (such as macrogonal boron nitride or carbon) can improve both wear resistance and lubricity. Can be done.

By the way, in order to improve the machinability of iron-based carbon steel and alloy steel, Ca (0,001 to 0.01% by weight), S (0,04 to 0.12% by weight), and Pb (0. ,04～0
．． 30% by weight), but S and pb
cannot be easily added to A2 alloy, and Ca
Since this degrades the performance of A2 alloy, there is no example of adding additives to the A2 alloy casting material itself in order to give it free machinability.

Therefore, by adding self-lubricating particles using the method for producing alloy castings of the present invention as described above,
The case of manufacturing Affi alloy castings with improved machinability will be described.

First, an An alloy casting material 2 in a crucible 1 is heated and held (570 to 900°C) with a heater 3, and then self-lubricating hexagonal boron nitride (hBN) particles (particle size: 0
．． 1 to 500 µm theory) 0.05 to 3% by weight of 4 is added. In this case, the specific gravity of the A1 alloy casting material 2 in the above temperature range is about 2.3 to 2.7, and the hexagonal boron nitride particles 4
has a true specific gravity of 2.27 and has a smaller apparent density, and also has poor wettability, so it floats. Therefore, in normal casting, hexagonal boron nitride particles 4 are used as A2 alloy casting material 2. It is impossible to combine Therefore, in this example, a molten metal 2a of an Al1 alloy casting material 2 to which hexagonal boron nitride particles 4 are added is heated and maintained by a heater 3.
Or, by using one to three stirring members 8 (for example, screws machined in the opposite thread direction, helical gear, spiral gear, etc.) shaped to apply downward force to the semi-molten A2 alloy casting material, 100~ 10.00Or,p,
m, and mechanically stirred to form hexagonal boron nitride particles 4.
I! , molten metal 2a of alloy casting material 2 or semi-molten AI
1 alloy casting material 2 is forcibly composited. and,
The composite molten metal 2a of the 81 alloy is poured into the mold 1 through the melt inlet 10 of the crucible 1, either sequentially during stirring or all at once.
1. Inject it into a container and let it cool and solidify.

Since the 81 alloy casting 13 thus obtained has self-lubricating properties, the machinability is improved.

Incidentally, AC9A (A1-5i specified by JIS standard)
-Cu-Ni-Mg-based aluminum alloy castings) with a thickness of about 50 mm Aj! The alloy was polished using a 5LNa disc grindstone (
The cutting speed when continuously cutting with 00φ200 x t2) is about 3 m/s, but as mentioned above, the cutting speed of a composite of hexagonal boron nitride particles 4 is about 5 to 20 m/s. . It should be noted that there is a correlation between the amount of hexagonal boron nitride particles 4 added and the cutting speed, and this correlation is shown in the shaded zone in FIG. 5. Thus, by adding hexagonal boron nitride particles, the cutting speed can be improved several to ten times as compared to the conventional A1 alloy.

6 to 8 show a second embodiment of the present invention, and schematically illustrate the manufacturing process of an alloy casting made by adding and compounding a fibrous high-melting point metal or alloy to a low-melting point alloy. This is illustrated in the figure.

First, as shown in Fig. 6, a low melting point alloy (for example, Al2, Mg, Zn, Pbn
An alloy casting material 15 consisting of an alloy of Sn, Bi, etc.) is placed in the crucible 1, heated and melted by a heater 3, and held. The heating temperature at this time is within the complete melting temperature range (for example, 8It: 660°C or higher, Mg: 650°C or higher,
Zn: 420°C or higher, Pb: 328°C or higher, Sn
: 232'C or higher, Bi: 272°C or higher), or partial melting temperature range (for example, 548°C for AN-Cu alloy)
~660°C). As a result, the alloy casting material 15 is melted in the crucible l, and the molten metal 15a (see Fig. 2)
becomes.

Next, as shown in Fig. 7, the cross-sectional area is lXl0-'~1
short fibrous high-melting point metal with a length of 0.1 to ioam (e.g., W with a melting point of 800°C or higher, Ni+ Ti+
Fe.

Cu) or alloy (hereinafter referred to as fibrous material 16) is added in an amount of 5 to 25% by volume to the above-mentioned molten metal 15a.

Note that this addition is not limited to after melting the alloy casting material 15, but may be performed before or during heating of the alloy casting material 15.

Thereafter, the molten metal 15b to which the fibrous material 16 has been added is stirred by the mechanical stirring means 5 to 100%
Add mechanical stirring of N10.00Or, p, m. As a result, the added fibrous substances (short fibers) 16 are intertwined with each other and composited in a uniformly dispersed state in the molten metal 15a.
The alloy is injected into the mold 11 through a tube and rapidly solidified, and the obtained lump-like aggregate is recovered as an alloy casting 17. Thereby, the crystal grains of the matrix alloy can be made finer, and a stronger composite casting can be obtained.

Although the embodiments of the present invention have been described above, the present invention is not limited to the embodiments described above, and various modifications can be made based on the technical idea of the present invention.

For example, the base alloy casting material may be any of various alloys, and the configuration of the mechanical stirring means 5 may be changed as appropriate.

e. Effects of the Invention As described above, in the present invention, particles with good wettability are added to the molten alloy, and the crystal grains of the alloy casting are solidified by mechanical stirring. It is possible to make the grains finer, thereby increasing the strength and toughness, and also to eliminate the directionality of the crystal grains, thereby eliminating the direction in which the strength and toughness are poor. Furthermore, by adding particles with high hardness, wear resistance can be improved, and by adding particles with self-lubricating properties (for example, hexagonal boron nitride, carbon, etc.), wear resistance and lubricity can also be improved. be able to.

Furthermore, the present invention is a method in which a fibrous high-melting point metal or high-melting point alloy is added to a molten metal of a low-melting point alloy, and the fibrous metal or high-melting point alloy is rapidly solidified by mechanical stirring. The strength and toughness of alloy castings can be increased by compositing fibrous substances, and the fibrous substances can be entangled with each other by mechanical stirring, providing alloy castings with superior strength and toughness. can. Furthermore, since the added fibrous substance is a metal or alloy, it has good wettability (compatibility) with the mother alloy, so i8? J) Manufacture is easy because there is no need to apply high pressure (50 kgf/c4 or more) unlike forging (pressure forging).

[Brief explanation of the drawing]

Figures 1 to 3 show an embodiment of the present invention, with Figure 1 being a cross-sectional view showing the alloy casting material placed in the crucible, and Figure 2 showing the molten alloy casting material being placed in the crucible. A cross-sectional view showing the state of adding particles, Figure 3 is a cross-sectional view showing the state of mechanical stirring of the molten metal and rapid solidification in the mold, and Figure 4 shows crystal grains when the molten metal is naturally solidified in the mold. Cross section, 5th
The figure is a graph showing the correlation between the amount of hexagonal boron nitride particles added and the cutting speed. 2 is a sectional view similar to that of FIG. 2, and FIG. 8 is a sectional view similar to FIG. 3. 1... Crucible, 2... Alloy casting material, 2
a, 2b... Boiling water, 3... Heater, 4... Particles, 5... Mechanical stirring means, 11... Mold, 12... Water cooling cylinder,
13... Alloy casting, 15... Alloy casting material made of low melting point alloy, 15a,
15b... Molten metal, 17... Alloy casting. Figure 4 is 1°Ju& (mm/s)

Claims (2)

[Claims] (1) An alloy casting made by adding particles with good wettability to a molten alloy, mechanically stirring the molten metal, and rapidly solidifying the molten metal. (2) An alloy casting made by adding a fibrous high-melting point metal or high-melting point alloy to a molten metal of a low-melting point alloy, mechanically stirring the molten metal, and rapidly solidifying the molten metal.